SUMMER 2010
BRINGING BETTER HEALTH TO YOUR HORSES
TARYN HOLTBY
Young equine steward of 2010 DEWORMING
Too much of a good thing?
GENETIC STUDY SPOT ON
Gene links coat patterns and night blindness
WESTERN COLLEGE OF VETERINARY MEDICINE • EQUINE HEALTH RESEARCH FUND
I N S I D E
4 Pergolide’s Dose Strength Critical to Health
PhD student Dr. Katherine Ball shows that concentrations of pergolide
are lower than expected in compounded doses.
6 $76,000 for Seven Studies
The EHRF earmarks $76,000 for seven equine research studies that
will be conducted by WCVM researchers during 2010-11.
8 Dr. Claire Card: Equine Baby Maker
WCVM’s Dr. Claire Card has helped to bring many foals into the world
that wouldn’t have been born without a helping hand from science.
11
Putting a Prairie Spin to Deworming
A WCVM study will investigate the intestinal parasite load of horses
living on the Prairies so clinicians can establish Prairie-based
deworming programs.
13 Young Equine Steward
Horses and equine welfare have a special place in the heart of thirdyear veterinary student Taryn Holtby of Marshall, Sask.
14 Genetic Study Spot On
A new study confirms that a single gene causes congenital stationary
night blindness and leopard complex spotting in Appaloosas.
ON OUR FRONT COVER: Third-year veterinary student Taryn
Holtby received the 2010 Equine Welfare Young Steward of the
Future Award of Distinction this spring. Visit page 13 for more
details.
ABOVE: A horse and rider compete in the team penning event
at the 2009 Canadian Western Agribition in November 2009.
H O R S E
H E A L T H
L I N E S
Horse Health Lines is produced by the Western College of Veterinary Medicine’s
Equine Health Research Fund. Visit www.ehrf.usask.ca for more information. Please
send comments to:
Dr. Hugh Townsend, Editor, Horse Health Lines
WCVM, University of Saskatchewan
52 Campus Drive, Saskatoon, SK S7N 5B4
Tel: 306-966-7453 • Fax: 306-966-7274
wcvm.research@usask.ca
For article reprint information, please contact sm.ridley@sasktel.net.
CFIA INTRODUCES NEW REGULATIONS: Effective
July 31, the Canadian Food Inspection Agency (CFIA) is making
it mandatory for all federally-inspected equine facilities to have
complete records dating back six months for all domestic and
imported horses presented for slaughter.
The CFIA’s new requirements for horses intended for human
consumption include records of identification information, diagnosed
illnesses as well as all vaccines and medications administered
or fed to the animals. To assist horse owners in collecting all of
the necessary information, CFIA has introduced a new Equine
Information Document (EID) that can be found on its web site. The
site also lists substances that are not intended for use in food animals.
The EID is the first step in developing a comprehensive food
safety and traceability program for the Canadian equine industry
— for both domestic and international markets. For more
information, visit the CFIA web site at www.inspection.gc.ca. CHANGE IN RESEARCH LEADERSHIP: WCVM
professor and researcher Dr. Baljit Singh will become the College’s
acting associate dean of research for a one-year term on July 1, 2010.
Singh takes over the job from Dr. Norman Rawlings who retires on
June 30 after eight years in the role and a total of 35 years of service
at the WCVM.
Singh, a professor in the Department of Veterinary Biomedical
Sciences, has developed a comprehensive research program that
focuses on cell and molecular biology of lung inflammation. His
team is involved in several equine health-related projects that target
the inflammatory aspects of laminitis and endotoxemia.
As part of his new role, Singh administers the College’s family
of research funds — including the Equine Health Research Fund
(EHRF) and the Companion Animal Health Fund (CAHF). SUCCESSFUL EQUINE SEMINAR: More than 200
local 4-H and Pony Club members visited the WCVM on January
30 to participate in the Equine Club’s annual Equine Seminar
day. Organized by WCVM undergraduate students, this year’s event
included sessions on equine lameness, emergency first aid for horses,
bugs and parasites that affect horses, and other equine health care
topics.
Veterinary students created and presented all of the sessions that
were geared toward different knowledge levels among the 4-H and
Pony Club members. All participants also received copies of Horse
Health Lines from the Equine Health Research Fund booth.
The WCVM Equine Club, which operates as a student chapter of
the American Association of Equine Practitioners (AAEP), organizes
the annual event as part of its community involvement. Each year,
the EHRF also supports one of the Equine Club’s wet labs that provide
undergraduate veterinary students with valuable hands-on experience
with equine-related health procedures. This year, the Fund supported
the club’s dentistry wet lab that took place in March 2010.
New Dean:
DR. DOUGLAS FREEMAN Dr. Douglas Freeman, the Western College of Veterinary Medicine’s
sixth dean in its 45-year history, began his five-year term on March 1, 2010.
Freeman replaces Dr. Charles Rhodes who retired on February 28 after 39
years of service with the college.
During his 26-year career, Freeman has gained a valuable range of
experience as a veterinary practitioner, a faculty member in both academic
and clinical science departments, and an administrator. He has worked in
academic institutions in the United States as well as overseas. His experience
also includes private veterinary practice and veterinary professional services
in the animal health industry.
For the past nine years, Freeman was a professor and head of two
departments — Veterinary Diagnostic Services and Veterinary and
Microbiological Sciences — at North Dakota State University in Fargo, N.D.
Freeman completed a Doctor of Veterinary Medicine degree, a
clinical residency and a Master of Science degree in theriogenology at the
University of Minnesota. He received a PhD in reproductive physiology
from the University of Idaho and is a diplomate in the American College of
Theriogenologists.
During his term at North Dakota State University, Freeman served as
director of the NDSU’s Great Plains Institute of Food Safety for two years,
and led multi-disciplinary research programs in disease surveillance, public
health and food
safety. He was
selected as an
American Council
on Education
Fellow in 2006,
and spent one year
at the University
of Minnesota
where he gained
experience
in academic
leadership and
administration
of the university’s
Academic Health
Center.
Horses have
played a significant role in Freeman’s career. Equine theriogenology was
the focus of his residency and graduate work, and he has been involved in
a number of research studies that addressed questions related to equine
reproductive physiology, assisted reproduction and equine welfare. Freeman
served as director of the equine studies program at the University of
Massachusetts from 1995 to 2001. He has also been involved in the equine
ranching industry as a veterinary consultant and advisory board member for
the past 15 years.
EHRF AT AGRIBITION: In late November, the Equine Health
Research Fund (EHRF) had the chance to participate in the 2009 Canadian
Western Agribition — thanks to the Saskatchewan Horse Federation. The
organization allowed the Fund to share some of its booth space during
the week-long agricultural show in Regina, Sask. As well, SHF staff and
volunteers graciously answered visitors’ questions about the WCVM and took
care of stocking EHRF reading materials during the show
The annual event attracts thousands of western Canadians — including
a large number of horse owners and breeders — so it was the ideal venue for
promoting the College’s equine health research and training programs. The
WCVM and the Fund are grateful to the SHF for the opportunity to participate
in last year’s event. ABOVE: Dr. Tamara Quaschnick at work during her clinical
internship at the Idaho Equine Hospital. Photo: Trish Hammell
WCVM GRADUATE FEATURED ONLINE: Dr. Tamara
Quaschnick, the 2009 recipient of the WCVM Faculty Gold Medal and a longtime horse enthusiast, is featured in a Q & A article on the WCVM web site.
During her time at the College, Quaschnick was very active in the WCVM
Equine Club as well as the WCVM Students Association and the Canadian
Veterinary Medical Association. After graduation last spring, Quaschnick
headed to Nampa, Idaho, to complete a one-year internship at the Idaho
Equine Hospital. Once her internship wraps up this summer, she plans to
return to her home province.
“I’m headed back to Hanna to work in the local mixed animal practice.
I have a real heart for rural Alberta and look forward to being part of a
community,” says Quaschnick, who grew up on her family’s ranch near
Hanna, Alta.
To read more of the interview, please visit www.wcvm.com and key in
“Quaschnick” on the site’s search feature.
Western College of Veterinar y Medicine
3
Pergolide’s
Dose
Strength
Critical to
Horse Health
W
hile in practice, Dr. Katherine Ball recalls prescribing pergolide
— a treatment for horses diagnosed with Cushing’s disease or
pituitary pars intermedia dysfunction (PPID) — and wondering
why some of her equine patients didn’t respond to the drug as well as expected.
Now the WCVM graduate student knows what may have happened: the
horses were probably under-dosed because of insufficient pergolide in their
prescription solutions.
Pergolide, the drug of choice for controlling PPID, was once used to
treat Parkinson’s disease in humans but was pulled from the market in 2007
after studies showed that the medication caused adverse effects in people —
including heart failure.
“The only option left to veterinarians was to have a compounding
pharmacy formulate pergolide, the active pharmaceutical ingredient, into
either tablets or liquid suspensions,” explains Ball, a PhD student and a
veterinary clinical pharmacology resident in
WCVM’s Department of Veterinary Biomedical
Sciences.
Compounding pharmacies
are frequently asked to develop
formulations for specific cases
where there’s no suitable
commercial product that’s
available and licensed.
Stories by Lynne Gunville
Ball began to question these pergolide formulations in 2007 when Dr.
Gordon McKay, Ball’s forensic toxicology professor, gave her an assignment
analyzing two samples of pergolide being administered to a horse with PPID.
The owner and clinicians at the WCVM Veterinary Teaching Hospital were
questioning why the prescriptions weren’t alleviating the symptoms.
Her results were surprising. “We found that both samples contained
about 60 per cent of the pergolide concentrations they should have contained
— a pretty substantial decrease in dose,” says Ball. “Treatment with a lower
dose (of pergolide) than intended may increase the horse’s risk of developing
laminitis and chronic infections. That’s potentially a very serious and
ultimately life-threatening issue for the horse.”
Later, Ball had the opportunity to further explore the subject of pergolide
concentrations in greater depth with residency supervisor, Dr. Trish Dowling,
and McKay. “It really evolved out of curiosity. We had been left with some
pretty significant questions,” explains Ball. “So curiosity kills the proverbial
cat, but it also makes the grad student very busy.”
Q. What is Cushing’s disease?
A. Cushing’s disease, or pituitary pars intermedia
dysfunction (PPID), occurs when abnormal function of
the hyptholamus, pituitary and adrenal glands lead to
excessive levels of corticosterioids — with cortisol being
the most harmful. PPID makes horses more predisposed to
laminitis and chronic infections. The most common visible
sign of the disease is an abnormal haircoat (overgrown,
wavy hair) along with a pot-bellied appearance. This
hormonal disease, which tends to affect older horses and
is more common in ponies, cannot be cured but can be
controlled.
“Treatment with a lower dose
(of pergolide) than intended
may increase the horse’s risk
of developing laminitis and
chronic infections.”
Ball resolved to answer three questions about pergolide
solutions prepared at compounding pharmacies. She wanted
to see how consistent the concentrations would be, how stable
the solutions would be and if the formulation — the recipe
— affected the stability of the compound.
She began by obtaining three batches of pergolide from
three pharmacies, providing nine samples in total. Using
high-performance liquid chromatography (HPLC) to separate
and measure specific molecules in the samples, she analyzed
the pergolide concentration of each solution on a regular
basis from the day of receiving the samples up until five
months later.
“What was most striking was the nature of the
initial concentrations,” reports Ball. “None of the initial
measurements of pergolide concentrations fell within the
range of variability that’s considered acceptable.” The other
questions to be answered concerned the stability of the
solutions. Here the researcher was pleasantly surprised by the
results which showed no specific degradation of the samples
over the study period.
Ball plans to submit her results to the Journal of
Veterinary Pharmacology and Therapeutics and says that
the findings are significant for veterinarians. If they know
that concentrations of pergolide are unpredictable, they’re
more likely to monitor their patients and adjust the dosages in
order to get better results from the treatment. And by having
their pergolide solutions prepared by the same compounding
pharmacy, they improve the likelihood that the concentrations
are similar. Ball also emphasizes that veterinarians and horse
owners should take steps to maximize the shelf-life of the
solutions by storing them in the fridge with minimal light
exposure.
She adds that there are still a lot of unanswered questions
about pergolide and hopes to see future research into the
product, particularly into learning what blood concentrations
of the drug lead to therapeutic success.
Ball emphasizes that compounding pergolide can be
challenging for the pharmacies due to the tiny quantities
of bulk drug that require precise measurement, and she
credits the pharmacies for their assistance with her study.
“They all enthusiastically provided their samples to the
study, which indicates to me that they’re really interested in
providing a good quality product. Their goal is the same as
the veterinarians and horse owners — they want to ensure the
horses are treated effectively so they can be healthy.” H
Dr. Katherine Ball: “I’m seeing things
that nobody has seen before.”
Horses and Science DO MIX
Dr. Katherine Ball was two when she had her first horseback ride.
“It was actually my aunt that got me onto a horse for the first time.
She convinced my folks that they should take me for lessons, and
that was their fatal mistake!”
Her parents bought Ball’s first horse for her when she was seven,
and she remembers that, despite being a city kid from Regina, she
spent most of her time in the barn. She began training and showing
horses, particularly reining horses, winning awards at some of the
largest shows in Western Canada and the northwestern U.S.
After graduating from WCVM in 2002, her work in mixed
practices left her a lot less time for riding. “Your first years in practice
are so busy. You’re learning stuff, you’re on call, you’re going a
million miles a minute,” explains Ball. “It was really difficult to keep up
the horse career.”
In 2006, Dr. Trisha Dowling invited her back to WCVM
for graduate studies and a residency in veterinary clinical
pharmacology. Ball started on her Master’s degree but switched
into the PhD program after securing a substantial research grant to
fund her thesis research.
A self-proclaimed geek who loves talking science, Ball is
enthusiastic about her PhD project that explores the use of gallium
compounds for treating urinary tract infections in dogs: “This work
will ultimately be destined for human treatment, and the exciting
twist is that I’m using synchrotron imaging techniques for part of the
investigation. I’m seeing things that nobody has seen before.”
Still a horse enthusiast at heart, Ball has enjoyed her research
focused on pergolide, a treatment for equine Cushing’s disease — a project that provides significant information for veterinarians, horse
owners and compounding pharmacies.
Although Ball is horseless at the moment, she welcomes any
opportunities to stay involved in the horse world. “I’ve done some
judging and occasionally get to give little mini lessons and give
my advice on buying and selling horses. I have every intention of
getting back into it once I’m out of graduate school.”
In the meantime she’s enjoying her work at WCVM: “It’s a
privilege to be back at school and have the opportunity to explore
new avenues. I just like being able to ask a question and then have
the time to explore potential answers.”
Western College of Veterinar y Medicine
5
$76,000
for 7 Studies
The Equine Health Research Fund
(EHRF) has earmarked just over
$76,000 for seven horse health
studies at the Western College of
Veterinary Medicine (WCVM). For more
details, read the following snapshot
descriptions of the projects that will be
completed by WCVM researchers and
their collaborators over the next couple
of years.
How does arthrodesis affect carpal flexion?
Drs. Spencer Barber and Luca Panizzi, WCVM: Dr. James Johnston,
U of S College of Engineering; and Patty Tulloch and Hayley Lang,
WCVM students
Injuries to the carpal joints are common in horses and frequently
result in arthritis that can be painful and debilitating. Arthrodesis,
surgical fusion of the joint, has occasionally been used to treat arthritis
or fractures of the carpus. But the animal’s quality of life and its
usefulness after the fusion depend on the amount of carpal flexion
that remains after surgery. This study will determine how each of three
different arthrodesis techniques affects carpal flexion.
Researchers will utilize a biomechanical testing procedure to measure
the flexion of the untreated carpal joints on 10 cadaver limbs. In random
order, they will then perform three partial carpal arthrodesis techniques
on each limb: fusing the antebrachiocarpal joint, fusing the middle and
carpometacarpal joint, and fusing the carpometacarpal joint using two bone
plates.
After each technique, the research team will use biomechanical testing
to measure the amount of carpal flexion. This multi-disciplinary project
will help owners of arthritic and injured horses to make informed decisions
regarding surgical treatment options and will support the advancement of
current treatment methods for carpometacarpal disease and injury.
Is coronary band grafting a speedier treatment
option?
Drs. James Carmalt and Imma Roquet, WCVM
Horses frequently suffer injuries to the coronary band – the thin band
around the top of the hoof that’s responsible for hoof growth. Clinicians commonly treat the injury and then immobilize the limb in a foot cast. Recovery
time varies, lameness may persist and permanent hoof wall defects may occur. This study will investigate if coronary grafting paired with casting could
improve and speed healing.
6
Horse Health Lines • Summer 2010
ABOVE: Dr. Steve Manning and his team will investigate
whether acupuncture therapy is effective for inducing
ovulation in mares this summer.
The investigators will surgically remove a square patch involving skin
and dorsal hoof from both the right and left front limbs of five horses. They’ll
suture one flap onto the defect in the other foot, while the second flap will be
transplanted onto a defect in another horse. Both limbs will be placed into
foot casts for four weeks. The casts will then be removed, and researchers will
assess graft integration and hoof wall growth. They’ll then monitor the horses
for eight weeks in paddock conditions, comparing the rate of hoof growth in
the grafted sections and the non-grafted sections.
Results could lead to the use of coronary band grafting as a means to
speed the healing of chronic defects or acute lacerations and tearing involving the coronary band.
Do western Canadian horses require different
deworming protocols?
Drs. Chris Clark, Ela Misuno, Steve Manning, Lyall Petrie, Emily Jenkins
and Fernando Marques, WCVM
While intestinal parasitism is a common, worldwide problem of horses,
there is little specific information about horse parasites in Western Canada
where the combination of long, severe winters and low humidity in the
summers may result in fewer numbers. Because of concerns that parasites
are becoming resistant to dewormer products, it’s important to understand
the life cycle of these parasites in the region so existing products are used
effectively.
Researchers will monitor 60 mares and their foals for 12 months,
evaluating fecal egg count (FEC) monthly over the summer and twice during
the winter months. None of the horses will receive deworming treatments
unless individual animals show a high FEC or clinical signs. If this occurs,
affected horses will receive ivermectin. A follow-up fecal egg reduction test
will establish whether the deworming treatment is effective and will thus
detect resistance to ivermectin.
Study results will be used to develop more appropriate deworming
protocols and to determine if parasite resistance to ivermectin is a problem in
the local horse population. Researchers may use this data for a larger project
to develop novel control methods for these parasites.
Can acupuncture induce ovulation in the mare?
Drs. Steve Manning, Nora Chavarria, Claire Card and Manuel Chirino,
WCVM
Acupuncture has become a common alternative treatment for many
reproductive problems in horses. However, much of the evidence for its
effectiveness is anecdotal or pertaining to other species.
WCVM researchers want to objectively investigate acupuncture as an
adjunct therapy for equine sub-fertility or infertility. They’ll perform a
randomized, controlled and double-blinded trial to scientifically establish
if electro-acupuncture is valuable for inducing ovulation.
Thirty mares in estrus will be randomly assigned to three groups:
negative control (NC) will receive a sterile saline solution injection,
electro-acupuncture (EA) will receive 15 minutes of treatment at discrete
acupuncture points once daily until ovulation, and positive control (PC) will
receive an injection of human chorionic gonadotropin, a proven ovulation
induction agent. Tests including palpation, ultrasound and blood analysis
will be performed at regular intervals. Researchers will observe ovulation and
compare the mares’ reproductive hormone profiles.
Study results will help veterinarians and horse owners to make sound
decisions about using acupuncture therapy for ovulation induction. They
may also lead to further trials testing the impact of electro-acupuncture on
shortening the normal transitional period and advancing the physiologic
breeding season.
Can hair cortisol concentrations indicate stress in
racehorses with EGUS?
Drs. Fernando Marqués, José Alberto Ruiz López, David Janz, Brian
Macbeth and Marc Cattet, WCVM
Equine gastric ulcer syndrome (EGUS) is common in horses,
particularly Thoroughbred racehorses in active training. EGUS has a
significant economic impact due to the costs of diagnosis and treatment
and its impact on athletic performance. Although gastroscopy successfully
diagnoses EGUS, a simpler, less invasive technique is needed.
Since increased cortisol concentration in hair has been successfully
linked to long-term stress in primates and wild animals, the multidisciplinary research team will investigate the relationship between the
severity of EGUS and the cortisol concentrations in hair collected from 60
racehorses. They will also evaluate cortisol concentration in serum from the
horses — a reflection of acute stress response.
Serum and hair cortisol concentrations from a control group will be
compared to those of the “EGUS group” — the horses in which veterinarians
have already conducted gastroscopies to identify and grade the severity of
EGUS lesions. Study results will advance understanding of acute and longterm stress as EGUS risk factors and will validate a simple, non-invasive
technique for identifying horses at risk.
Is gallium maltolate effective for treating equine
proliferative enteropathy?
Dr. Julie Thompson, Canadian Light Source; and Drs. Trish Dowling,
Don Hamilton and Francesca Sampieri, WCVM
Lawsonia intracellularis (LI) is the bacterial pathogen causing equine
proliferative enteropathy (EPE), an emerging intestinal disease of domestic
and wildlife species. Prevention of EPE on farms is difficult since exposure
to LI occurs through the fecal-oral route, and the location of the bacterium
within the intestinal cells protects it from immune response and traditional
antimicrobial drugs. Gallium maltolate (GaM), a metal-based compound,
may be a viable therapy alternative for intracellular infections.
A WCVM-based research team will attempt to establish that hamsters
are suitable as an infection model for horses affected by EPE. Like horses,
hamsters are hind gut fermenters so their response to antimicrobial treatment
should be similar. Researchers will test for the presence of infection in LIchallenged and healthy control groups of hamsters at regular intervals over
21 days.
The research team will then compare the efficacy of GaM against five
antimicrobial drugs commonly used to treat clinical EPE. As gallium is a
metal, its intracellular killing action against LI will be investigated using
novel radiation techniques at the Canadian Light Source’s synchrotron — a high-energy particle accelerator used to probe the structure of matter. The
study’s results could influence treatment of infectious gastrointestinal disease
in veterinary patients, and may ultimately be utilized in treating human
infection.
Is a novel suture technique for laryngeal tie-back
more effective?
Drs. David Wilson and James Carmalt, WCVM
Laryngeal hemiplegia (roaring) is a performance-limiting
condition that primarily affects horses over 15 hands in height, including
Thoroughbreds, Warmbloods and draft breeds. Mainly because of nerve
dysfunction, the muscles of the larynx don’t function properly affecting the
abduction of the left arytenoid cartilage as the horse breathes. This cartilage
gets pulled into the airway, thus inhibiting respiratory function and resulting
in exercise intolerance.
A laryngeal prosthesis procedure, which is the preferred treatment, often
does not maintain the desired degree of abduction over time. In this study,
Drs. David Wilson and James Carmalt will evaluate the feasibility of a new
technique in which two sutures are placed in a two-loop pulley configuration.
This technique should ensure immediate load sharing that will reduce
suture tension and facilitate tying a “millers” knot configuration so that the
prosthesis will effectively maintain the desired degree of abduction.
Researchers will use a material-testing machine to compare the
biomechanical properties of the novel technique to those of the standard
technique that utilizes two interrupted sutures. Results could facilitate a new,
longer lasting technique for managing clinically affected horses. H
Western College of Veterinar y Medicine
7
Equine Baby Maker
Dr. Claire Card and her research
partners have played a positive
role in bringing many foals into
the world that wouldn’t have
been born without a helping
hand from science.
U
nlike other livestock industries, it’s common for horse owners to
breed valuable broodmares that are in their late teens or early
20s. “However, it’s not so easy for these mares to become pregnant
anymore, so we need to meet these reproductive challenges with some
evidence-based medicine,” says Card, professor of equine reproduction at
the Western College of Veterinary Medicine.
Although equine reproduction has been Card’s focus for nearly two
decades, it didn’t quite start that way. After graduating from the New York
State College of Veterinary Medicine in 1986, she juggled her time between
mixed animal private practice and graduate school at Cornell University
where she studied the fetal physiology of goats. Card finished her PhD
degree in 1990. In 1991, she became a diplomate of the American College
of Theriogenologists (ACT) and the WCVM’s newest equine reproduction
specialist.
Changes in the horse industry created a need for more basic
reproductive research and more studies targeting foal health. With the
increased use of artificial insemination, there was also a demand for applied
research to support assisted reproductive procedures.
That set up an ideal environment for Card and her graduate students
who took ideas from their clinical work and conducted research that could
be directly used in the field. As well, there was research funding available
through organizations like the WCVM’s Equine Health Research Fund,
Alberta Agriculture Research Institute, and the American Quarter Horse
Association.
Some of Card’s early collaborative projects covered congenital
hypothyroidism with Dr. Andy Allen and causes of foal mortality with Dr.
Shawn Haas — a project that was done with the equine ranching industry’s
assistance. Equine ranchers also helped her and Dr. Steve Manning as they
looked at the relationship between endometrial biopsies and mare fertility,
and low dose insemination. As well, Card and her graduate student, Dr.
Natalie Bragg, interpreted ultrasound images and developed guidelines for
analyzing reproductive tissues to predict ovulation.
The increased use of frozen semen created demand for more
information about the factors affecting the fertility of preserved semen —
8
Horse Health Lines • Summer 2010
a research topic for Card and Dr. Theresa Burns. Since many mares
developed inflammation after breeding with frozen semen, endometritis also
became the focus of a project for Card and Dr. Farshad Maloufi.
Specifically, the two studied the response of problem breeding mares
and their susceptibility to inflammation post-breeding with frozen semen
and its preserving solution (extender). As well, they challenged the horses
with Streptococcus equi zooepidemicus — the number one cause of
uterine disease.
“If problem mares were bred when they had a non-bacterially
contaminated uterus, they performed as well as the resistant mares that
tended to be healthier and younger,” explains Card. “This emphasized the
clinical practices that we needed to engage to get some of these mares in
foal.”
When bovine specialists successfully used superovulatory treatments in
cows to achieve multiple ovulations and to increase the number of recovered
embryos, the horse industry took notice. As Card explains, using embryo
transfer in horses isn’t easy: on average, without superovulation, an embryo
is only produced about half the time.
Card worked with PhD student Dr. Tal Raz to develop protocols for
superstimulating mares with a new product, equine follicle stimulating
hormone (eFSH). They found that eFSH led to the recovery of more embryos
from the mares – but not all embryos were healthy. Since then, other
scientists have experienced similar problems and eFSH is no longer being
produced.
“In many cases, a product can initially look promising, but years later,
cumulative studies show it’s not very efficacious,” points out Card. “It’s
a question of taking an evidence-based approach when evaluating these
products.”
Now Card and her research team are returning to a previouslyinvestigated topic. Card wants to understand the immune response of mares
to physiologic (sperm-induced) and bacterial endometritis at the molecular
level, using the resources available in the WCVM’s new molecular laboratory.
Once funding is secured, Card will work with her collaborators: WCVM
researcher Dr. Baljit Singh whose research focus is on lung inflammation,
and Dr. David Horohov, an equine immunologist at the University of
Kentucky.
As a first step, Card and Dr. Sarah Eaton worked with molecular
specialist Dr. Vikram Misra and technician Noreen Rapin to investigate the
mares’ immune response to sperm. Then, they conducted pilot studies with
common uterine pathogens such as Strep. zooepidemicus and E. coli to
learn how different bacteria trigger distinct immune responses in the uterus.
Results showed that E. coli, a Gram negative bacteria, causes longer
and deeper inflammation within the uterine tissues versus Gram positive
organisms like Strep. zooepidemicus that cause superficial inflammation
and secretion of pus. To determine why Gram positive and negative
organisms produce different types of inflammation, Card and her colleagues
examined the horses’ rapid innate immune responses. Specifically, they
evaluated highly conserved Toll-like receptors (TLRs) in the uterus that
initiate cytokine secretion which control the body’s inflammatory response.
This work is connected to recent developments in the horse industry:
some practitioners use immunomodulatory agents to help treat mares
that have difficulty conceiving. In turn, other practitioners use antiinflammatory products to decrease inflammatory response.
At this point, Card says no one has conducted enough controlled,
evidence-based research to know how or whether these therapies are
effective. “We’re at a crossroads since it seems we need enough of an
immune response to eliminate the bacteria from the uterus. But when
there’s too much, excessive inflammation becomes the underlying reason
why a mare can’t support the embryo.”
It’s an area where Card hopes to contribute more knowledge by using
research models to assess new treatments. That ability to quickly respond to
emerging problems in equine reproduction and to assess potential therapies
is what Card has enjoyed most about her research.
“For me, research is satisfying in many ways and I do think we’ve
been successful in advancing our patient management through evidencebased research over the years,” points out Card. “We’ve helped make some
guidelines for people, and we’ve helped them to make good decisions about
their animals’ breeding future.”
Now Card’s early research experience with goats during her graduate
program has proven to be valuable for a project that she’s working on with
the support of Veterinarians Without Borders-Vétérinaires sans frontières.
Since 2006, Card has made a number of trips to Uganda where she
works with HIV-AIDS affected families to develop sustainable agriculture
— including goat production.
It’s another problem to solve, but there’s just one problem that Card
can’t fix: “There’s always more work than time.” H
Reprinted from the 2009 WCVM Research Report. To read
more profiles of WCVM researchers, please visit www.wcvm.
com/research and click on “Research Report.”
WCVM Visits Royal
Manitoba Fair
This spring, Manitoba horse enthusiasts had the
chance to learn more about the Western College of
Veterinary Medicine and the Equine Health Research
Fund by visiting the College’s display booth during the
2010 Royal Manitoba Winter Fair in Brandon, Man.
During the show’s six days, a team of local
veterinarians, veterinary technicians and horse people
handed out copies of Horse Health Lines and answered
a wide range of questions about the College, its equine
research and training activities, its admissions process, its
Veterinary Teaching Hospital and more.
Dr. Ross McKague (WCVM ’71) and a member of the EHRF
advisory board, played a major role in organizing Team WCVM for the
popular agricultural fair. Besides McKague and his wife Brenda, the team included Dr. Jennifer Beckwith,
Dr. Vicky Sempers, Dr. Allister Gray, Cherie Fleury, Peggy Edwards, Stephanie Inkster, Casey Wells, Meghan
Nicholls and Val Ferguson.
Another EHRF advisory board member, Dr. Nadia Cymbaluk, also pitched in by contributing a piece
of artwork for a fundraising raffle. Cymbaluk donated a framed print of an equine painting created by
Brandon-area artist Kim Penner. McKague presented the framed print to Taylor Park, a local horse enthusiast
(at right) who was the lucky winner of the draw.
Western College of Veterinar y Medicine
9
D
Too Much of a
Good Thing ?
Stories by Lynne Gunville
Every few months, horses across
Western Canada swallow a mouthful
of deworming paste while their
owners check it off on their calendars.
But are all of these deworming
treatments necessary?
10
Horse Health Lines • Summer 2010
r. Chris Clark, a specialist in large animal medicine at
the WCVM, hasn’t seen a lot of parasite-related diseases
— and he suspects it’s because most horse owners on
the Prairies regularly deworm their animals. But he questions
whether dewormers are being used unnecessarily and is concerned about the lack of consensus among clinicians regarding
how frequently animals should be treated.
“If you got a bunch of veterinarians together and asked
them how often should you deworm your horse, you’ll probably
get as many opinions as there are vets in the room,” speculates
Clark.
Many of those opinions are based on research from Great
Britain where there’s a high population density of horses and
a very wet, temperate climate — the perfect environment for
developing a large worm burden — and from Ontario where the
climate is quite different from that of the Prairies.
Climate is a key factor in the development of worm parasites. The eggs, which are passed in the feces of an infected horse,
typically go through some sort of maturation phase outside the
animal before being eaten by another horse. This time outside
the body is vitally important because the eggs need the right
temperature and humidity to mature.
“That’s why we need to look at how the western Canadian
Prairies differ from other parts of the world where the research
has been done,” says Clark. “Typically horses here have much
more space, we have less humidity in the summer and we have
dry, cold winters.”
Intestinal parasites are a common, worldwide problem
in horses. Although there’s a wide variety of worm parasites,
the large and small strongyles are of most concern in grown
horses while a roundworm called Parascaris equorum causes
problems mainly in foals. These parasites can cause significant
problems including colic, severe diarrhea and failure to grow
and thrive.
While deworming is an effective way to control these
parasites, some products have been so widely used for so long
that the parasites are becoming resistant to them. This resistance
is a critical issue that Clark hopes can be avoided in the Prairie
provinces by using informed, science-based deworming practices.
Measuring the fecal egg count (FEC) is the most accurate
way to determine whether or not deworming is required. The
fecal sample is collected from the horse’s rectum and then can
either be evaluated by a veterinarian or sent to Prairie Diagnostic
Services where technicians in the parasitology lab determine
the number of parasite eggs per gram of feces. Another simpler
qualitative test can be carried out by a veterinarian who simply
rates the sample as containing either a mild, moderate or severe
parasite burden.
Although the FEC isn’t commonly used, Clark believes the
results of a new study gauging intestinal parasite loads in the
Prairie region will provide solid evidence that new practices such
as taking routine fecal egg counts may be the best option for
horse owners. For example, in what Clark labels “the test and
treat mentality,” dewormers would not be used unless the FEC of
the animals exceeded 500 parasite eggs per gram of feces.
Based on the fact that not all horses within the same herd
will carry the same worm burden, another possibility would be
to rely on FECs to identify and
management practices with
“If you got a bunch of veterinarians
deworm only the ones that have
your deworming, you may be
together and asked them how often
a worm problem. This practice,
able to get a very good result
which could reduce the use of
for very little cost.”
should you deworm your horse, you’ll
deworming products, reflects the
Clark emphasizes the
probably get as many opinions as there importance of developing ways
common belief that 10 per cent
of the horses carry 90 per cent of
to use the existing products
are vets in the room.”
the worms.
more effectively since no new
Pinpointing the best time of the year for deworming might also make
medications are being developed. He hopes the results of his study will
for more effective treatments. Clark refers to research that has shown this
provide solid evidence on which people can base their deworming practices
strategy to be effective in other species. “When are you going to get the
— potentially saving them time and money plus taking some unnecessary
maximum bang for your buck? If you can pick the right time, maybe
stress out of their horses’ lives. H
you can get away with deworming only once a year. If you combine your
Putting a Prairie Spin to Deworming Programs
It was a conversation over coffee one morning that prompted a Western
College of Veterinary Medicine research team to investigate the intestinal
parasite load of horses living on the Prairies.
As Drs. Chris Clark and Steve Manning were discussing how often
horses in the region should be dewormed, they realized that there was no
solid scientific evidence to support their typical recommendations. “We’re
borrowing recommendations from other parts of the world that may not be
appropriate,” explains Clark. “The western Prairies need a western Prairie
deworming program.”
Shortly after that conversation, Dr. Ela Misuno began her residency in
large animal medicine at the College. Having worked in Denmark where
dewormers are sold by prescription only, she was well aware of the growing problems resulting from parasites becoming resistant to deworming
products.
Clark says that the timing was ideal: “Dr. Misuno joined us and had
this interest and experience, so it was a perfect fit as her residency project.”
Misuno, who has been instrumental in designing the project, will collect
and test fecal samples for parasite load while Clark and Manning will
co-ordinate the project.
The research team, which is funded by WCVM’s Equine Health Research Fund, also includes Dr. Lyall Petrie who has done extensive research
looking at parasite burdens in sheep and cattle, including a study of how
worm burdens in sheep change throughout the year. Dr. Emily Jenkins, a
veterinary parasitologist from WCVM’s Department of Veterinary Microbiology, will make her laboratory available to Misuno and help interpret the
data to determine whether or not the Prairie environment should influence
deworming practices.
The researchers will identify approximately 60 mare-foal pairs from
three local breeding farms and will follow them over a 12-month period.
Clark explains that they included the foals in order to investigate parasites
known to affect foals more than mares. They also want to determine
whether foals are exposed to a high worm burden from their mothers — a condition known to occur in sheep.
Misuno will collect and analyze fecal samples for fecal egg count
(FEC) every month through the summer, two to three times during the
winter, and once again in the spring. Deworming with Eqvalan® (ivermectin), which has been donated by Merial Canada, will occur only if testing
reveals a high FEC, and a follow-up count will be undertaken a week later
to ensure the treatment has been effective.
Farm owners will complete a detailed questionnaire providing information about their management practices. “There are so many variables
like what is the previous deworming program, what’s the population density of the pasture and how dry or wet is the pasture — all of these things
become quite complicated and that’s why we need this pilot study,” explains
Clark. “We need to work out how to do this on a much bigger level.”
The researchers plan to use their results to design a larger study that
will randomly select horses from individual farms and will provide veterinarians with the knowledge they need to advise horse owners on the most
effective deworming practices for their region.
“People are prepared to spend money and maintain their horses in the
maximum state of health,” says Clark. “We want to gather information so
we can give people firm recommendations that will ensure the health of
their animals.”
Clark emphasizes the importance of the initial project and says that
veterinarians in the Prairie area will be given those results so they can start
making recommendations that will enable horse owners to make informed
decisions about their deworming protocol.
“There might be a real change in the way that people view deworming.
We’ve always thought of just treating everything on the farm the same way.
Maybe we have to start treating each horse individually: getting those fecal
egg counts done and then deworming only the horses that need treatment.”
Clark points out that responsible deworming practices benefit everyone:
“First of all, it will ensure that the horses have optimum health. Then if we
can reduce the amount of money horse owners have to spend, that is obviously a benefit for them. And finally, if we use the drugs more effectively,
there will be no resistance problems and the horses will stay healthy for
years to come.” H
Lynne Gunville is a freelance writer and editor whose career
includes 25 years of teaching English and communications to adults.
She and her husband live at Candle Lake, Sask.
PRECEDING PAGE: A mare and foal at Jack and Shirley
Brodsky’s farm near Saskatoon, Sask. As part of their
deworming study, WCVM researchers want to determine
whether foals are exposed to a high worm burden from
their mothers.
Western College of Veterinar y Medicine
11
Q: What’s the turning point where selenium
becomes toxic to horses?
Too little selenium may be harmful, but excess
selenium may also be detrimental. Horses don’t perform well
when the selenium status is low. If you increase the amount
of selenium in the diet by 0.1 milligrams/kilogram, function
will improve. Horse diets typically contain about 0.3 mg/
kg selenium. At this concentration, the horse will do fine,
but as you increase the selenium in the diet, the function
will decline and may ultimately result in the death of the
horse. Concentrations exceeding 2.0 mg/kg in the diet are
potentially toxic.
SELENIUM
Handle with Care
On a Sunday afternoon in April 2009, trailers full of horses
belonging to Venezuela’s Lechuza Caracas polo team arrived at Palm
Beach’s International Polo Club in Florida, ready to compete at the
US Open Polo Championship. But as they were being unloaded, the
horses began collapsing. Within hours, 21 of the polo ponies were dead,
victims of a fatal overdose of the trace mineral selenium.
An antioxidant essential for proper functioning of animal cells,
selenium can be beneficial to working animals such as polo ponies
because it speeds muscle recovery after strenuous exercise. But in the
case of the Venezualan polo ponies, an error by a Florida compounding pharmacy resulted in blood concentrations of selenium that were
10 to 15 times higher than normal in the affected horses. The mistake
transformed selenium from a supplement into a poison. Commonly found in soil, groundwater and plants, selenium
is needed to stabilize the membranes in horses. Animals that are
deficient in selenium may develop rhabdomyolysis or tying up
syndrome, a painful degenerative disorder that affects the muscle cells.
In young horses a condition known as white muscle disease may result
from a deficiency.
Acute selenium poisoning is rare and causes a range of symptoms
including gait abnormalities, a distinctive garlic breath odour and
respiratory distress. Chronic toxicity is more common. It results from
long-term overexposure to selenium — often due to high selenium
levels in the plants or water being ingested. Horse owners need to
be on the lookout for signs such as hoof problems and hair loss in
the mane and tail. In extreme cases and usually after many weeks,
chronic toxicity, sometimes known as alkali disease, may result in
blindness and even death.
Although selenium is essential to horses, measuring the amount
of the mineral in their bodies and adding it to their rations can be
very tricky. Selenium levels have such a narrow margin of safety that
deficiency can turn into toxicity very quickly.
Dr. Barry Blakley, a toxicologist and head of WCVM’s Department of
Veterinary Biomedical Sciences, recently discussed some of the concerns
surrounding selenium supplements and toxicity levels in horses.
12
Horse Health Lines • Summer 2010
Q: Can horses develop selenium poisoning
just from eating plants?
Yes, they can. Selenium is found in all plants, but
some plants — loco weed and astragulus are two examples
— actually accumulate selenium. The smart horses don’t
eat them unless they’re forced to, but young horses aren’t too
discriminatory in their eating habits, and in some cases they
develop a taste for it.
Q: Can climate affect the storage of selenium in plants?
Yes. During drought conditions, plants contain more selenium. They’re not
necessarily toxic, but they’ll definitely have a higher level. And on the flip side of
that, typically in B.C. where they have very lush growth, the high water content in
the feed means there’s a lower selenium content. So horse owners in those regions
may need to add selenium to the diet.
Q: If you’re feeding your horse a supplement that has
selenium in it, and they’re also eating on pasture, is there
a potential for too much selenium in their diet?
The potential is there. If you’re using a lower concentration selenium
supplementation, it shouldn’t be a problem. If it’s at high concentrations and a
horse consumes a considerable amount of supplement, it would be a concern. It
would be chronic; it wouldn’t happen overnight and would not happen acutely.
It’s important to consider the intake of selenium from all sources including the
feed and the supplement.
Q: Do you see selenium poisoning from over supplementation very often?
In horses, we rarely see it. In species like cattle, goats and sheep we often
see producers — especially hobby producers — make errors in administering
it. There are injectable selenium products that you can purchase without any
difficulty. Selenium is relatively inexpensive and can be bought at many feed
stores. The veterinarian may not be involved, although selenium can be added to
the diet at higher concentrations with a veterinary prescription.
Q: Is there anything that can be done to counteract
selenium toxicity?
If you suspect selenium toxicity in one or more of your horses, contact your
veterinarian. If selenium toxicity is the problem, the best option is to increase the
supplementation of high-quality protein in the diet and add sulphur to it. The
sulphur binds with the selenium so it’s no longer available to the horse.
Your veterinarian may also suggest that you take your horses off the pasture
or hay in question until you have selenium levels tested in your horses and their
feed. If significant membrane damage has occurred, a full recovery may not
occur. H
Each year, the Farm Animal
Council of Saskatchewan
and the Saskatchewan
Horse Federation present
the Awards of Distinction
for Equine Welfare to
outstanding people in the
province’s horse industry.
This year’s recipient of
the Equine Welfare Young
Steward of the Future Award
of Distinction was Taryn
Holtby, a second-year
student at the
Western College of
Veterinary Medicine.
By Lynne Gunville
W
Taryn Holtby
EQUINE STEWARD
hen Taryn Holtby first announced that she wanted to be a
veterinarian, she was only three years old — too young to even
get the whole word out correctly. Now starting her third year at
Western College of Veterinary Medicine, she’s pursuing that dream, and her
love for animals — particularly horses — has never diminished.
Holtby says that growing up on a cattle farm near Marshall, Sask.,
probably led to her enthusiasm for veterinary medicine. Her role models were
the local veterinarians who came to their farm. “They were really good to me
and I wanted to be just like them. Dr. Glenn Weir owned the local clinic and
he always had chocolate in his pocket for any little kid. He’d always say being
a vet was the best occupation in the world.”
While Holtby enjoyed working with cows, she loved horses best, and the
horse she got when she was 12 still stands out in her memory. “CJ was well
trained, so my riding probably improved ten-fold when I started riding her.
She was really good to me and that horse knew more about me than most
people did — she heard lots from me whether she wanted to or not.”
Holtby was active in the local 4-H light horse club and belonged to many
other school and community groups. She especially enjoyed teaching riding
to children from Big Brothers Big Sisters and says that their enthusiasm was
the most rewarding part of the work.
She also worked at training and selling horses with the money going into
her education fund. “The training part is really cool to me,” says Holtby. “A
lot of my patience has to do with growing up with horses and working with
them. You can’t just tell them what to do. You have to show them and reward
them.”
Holtby entered the University of Saskatchewan’s College of Agriculture in
2006 with hopes of being accepted into veterinary medicine. That was when
she met Shirley Brodsky, a local Paint horse owner and breeder who was
involved with caring for horses recovering from cuts and wounds.
“I was going through horse withdrawal, so I went out and helped her.
A lot of it was learning about bandaging techniques as well as salves and
medications to promote the best healing. It was a wealth of knowledge,”
recalls Holtby.
She still found time for volunteering in college and city events and for
participating in sports – floor hockey, ice hockey, volleyball and curling. Her
summers were spent working on the family farm and volunteering at the
local veterinary clinics.
Once accepted by the WCVM in 2008, Holtby became active in many of
the college’s organizations — including the Equine Club. She’s the club’s
public relations officer and has helped to plan the last two equine seminar
days, an annual event where interested 4-H and Pony Club members come
to the college. “During the day, we give presentations or have interactive
activities, teaching them anything from nutrition to what to do in an
emergency with your horse,” explains Holtby.
Last summer, in addition to training horses and volunteering with 4-H
activities, Holtby gained valuable experience by working at Weir’s Veterinary
Clinic in Lloydminster, Alta. She especially enjoyed watching and learning
techniques for bandaging and suturing injured horses and says she benefited
from being part of a busy mixed animal practice.
This summer Holtby will help her dad on the farm while continuing to
train horses. She’ll also be on hand to help judge horse shows and may even
do a couple of shows with her own horse. She’s just starting to think about
her plans after graduation: although she hasn’t ruled out applying for an
internship, she’s leaving that decision until her fourth year.
“I’m not 100 per cent sure of where I’ll be in the future, but I’d really
like to keep working with horses and cows, my two big loves. I’ve always been
interested in equine dentistry and the wound healing lameness workup, so I
might further my education in some area of that,” says Holtby. “I’ll probably
end up working in a mixed practice, but I’d like to lean toward the horses
and cattle.”
As she looks back, Holtby appreciates the influence that horses have had
on her life. “I think horses help shape the people who are involved with them
into how they work with people and how they look at life. If you’re having a
bad day, you can always trust a horse. Horses have always had a special place
in my heart.” H
ABOVE: Taryn Holtby with a mare and foal at Jack and
Shirley Brodsky’s farm near Saskatoon, Sask.
Western College of Veterinar y Medicine
13
A
new study published by
scientists from the University
of Tampa and the University of
Saskatchewan solidifies the role of a single
gene in causing leopard complex spotting
and congenital stationary night blindness
(CSNB) in Appaloosa horses.
The gene, TRPM1 (transient receptor
potential cation channel, subfamily
M, member 1), was first identified in
2008 by the American and Canadian
researchers who had initially investigated
the correlation between particular spotting
patterns in Appaloosa horses and CSNB,
a condition that causes impaired night
vision in affected horses. The genetic work
is led by Dr. Rebecca Bellone, a molecular
Owyhee’s Eve, a black snowcap patterned Appaloosa, was one of 10
biologist at the University of Tampa.
homozygous Lp-patterned horses that participated in the WCVM study.
This most recent study, which was
Photo: Sheila Archer.
published this spring in Briefings in
Functional Genomics, attempted to find
the exact location of the mutation in the
TRPM1 gene that causes night blindness
and leopard complex spotting. This term is
used to describe a range of spotting patterns
Research study confirms that a single gene
on Appaloosa horses including snowcap
causes eye disease and leopard complex
blanket, few spot, varnish roan, spotted
blanket and leopard.
spotting in Appaloosas By Lynne Gunville
Ultimately, the researchers hope to
By conducting thorough eye examinations and electroretinographic
identify the mutation so a DNA test can be developed. This will allow
(ERG) testing, the WCVM researchers confirmed that CSNB was present
horse breeders and owners to make decisions about breeding and horse
only in the homozygous group, those carrying two copies of the Lp gene.
management.
ERG testing, used to diagnose CSNB, picks up the electrical information of
Although they couldn’t clarify the exact function of TRPM1, Bellone
photoreceptors and other cells in the horse’s retina as it responds to light.
and her collaborators were able to zero in on the genome region in which
“The eyes of the affected horses appear completely normal, but the
the mutation occurs and identified single nucleotide polymorphisms
ERG testing shows that there’s a disruption somewhere in the signal
(biological markers) that may point to its location and/or affect its activity.
transmission. Information is not getting through from the horses’ eyes
They have also established the foundation for further exploration of the
to their brains,” reported Sandmeyer, a veterinary ophthalmologist and
TRPM1 gene and the elements which may affect its expression.
an associate professor in WCVM’s Department of Small Animal Clinical
First described in the late 1970s, CSNB was thought to be a hereditary,
Sciences.
non-progressive condition found in some horses. Although most reported
Further investigation by researchers identified what was different
cases had involved Appaloosa horses, little was known about the disease
in the genes of the homozygous group by isolating RNA and analyzing
until 2005 when WCVM researchers Drs. Lynne Sandmeyer, Bruce Grahn
gene expression in the retinal and skin tissue samples collected by WCVM
and Carrie Breaux conducted a study investigating the clinical and
researchers. There was a decreased expression of a specific gene — TRPM1
electroretinographic characteristics of CSNB and its association with the
— in the eye and the skin of that one specific group.
leopard complex. They collaborated with Bellone and Sheila Archer, a
Bellone and her collaborators went on to investigate the significance
phenotype expert from Quill Lake, Sask. Archer co-ordinates the Appaloosa
of the TRPM1 gene. Seeking to pinpoint the mutation that either causes
Project, an international investigation into the genetic makeup of the
or is associated with the Lp and CSNB phenotype in horses, the researchers
Appaloosa breed.
genotyped tissue samples from nearly 200 horses in an effort to localize the
Based on previous research that had established the location of the
area of the mutation. In this most recent study, they were able to confirm
main Appaloosa gene called Leopard complex or Lp, the scientists studied
that the TRPM1 gene is the molecular mechanism for the spotting pattern
three groups of horses displaying three different coat patterns. The first
and the CSNB in animals carrying two copies of the Lp gene.
group had “few spot” or “snowcap” coat patterns and were homozygous
Understanding the TRPM1 gene may provide the missing pieces
for the Lp gene (carrying two copies of the gene). The second group had
to the puzzle surrounding CSNB in Appaloosas. Future research using
“leopard” or “blanket spotted” coat patterns and were heterozygous for the
the Appaloosa horse as a model could provide information crucial to
Lp gene (carrying only one copy of the gene). The final group of horses
preventing inherited CSNB in humans and could help scientists to better
were solid coloured and not carrying the Lp mutation.
Genetic Study SPOT ON
14
Horse Health Lines • Summer 2010
HUMAN SIDE OF TRPM1: Since the University of
Tampa-University of Saskatchewan research
team first identified the TRPM1 gene in
2008, their work has been cited by human
researchers who have found mutations of
the gene to be present in people diagnosed
with congenital stationary night blindness
as well. Here’s a summary of CSNB-related
discoveries in human medicine: •TRPM1 is mutated in human patients with
autosomal-recessive complete CSNB. •TRPM1 mutations are a major cause of
autosomal-recessive CSNB in individuals of
European ancestry. •TRPM1 was localized in the human retina to
the ON bipolar cell dendrites and the outer
plexiform layer. •TRPM1 is the channel gated by the mGluR6
signalling cascade. At least five human
ion channel-forming isoforms of TRPM1 are
in melanocyte pigmentation, melanoma,
brain and retina. •TRPM1 is an ion channel whose function
is critical to normal melanocyte
pigmentation and is thus a target for
pigmentation disorders.
Visit www.pubmed.gov and search for
“TRPM1” to view recent articles on the topic.
understand the process involved in relaying electrical response from
the eyes to the brain during night vision.
Related Publications:
Bellone RR, Forsyth G, Leeb T, Archer S, Sigurdsson S, Imsland
F, Mauceli E, Engensteiner M, Bailey E, Sandmeyer L, Grahn B,
Lindblad-Toh K, Wade CM. 2010. “Fine-mapping and mutation
analysis of TRPM1: a candidate gene for leopard complex (Lp)
spotting and congenital stationary night blindness in horses.”
Briefings in Functional Genomics. 9(3): 193-207.
Bellone RR, Brooks SA, Sandmeyer L, Murphy BA, Forsyth G,
Archer S, Bailey E, Grahn B. 2008. “Differential gene expression of
TRPM1, the potential cause of congenital stationary night blindness
and coat spotting patterns (Lp) in the Appaloosa horse (Equus caballus).” Genetics. 179(4): 1861-1870.
Sandmeyer L, Breaux CB, Archer S, Grahn BH. 2007. “Clinical
and electroretinographic characteristics of congenital stationary night
blindness in the Appaloosa and the association with the leopard complex.” Veterinary Ophthalmology. 10(6): 368-375. H
Our Survey Says . . .
Thanks to everyone who took the time to complete
the Horse Health Lines readership survey last year!
We appreciate your feedback as well as your
suggestions about what we can do to improve
future issues.
What did we learn? As an equine research-focused
publication, it was great to hear that our readers
are keen to hear more about the research projects
taking place at the WCVM. Here are more readers’
comments about Horse Health Lines:
•a reliable information source
•clear writing without being too technical
•practical health advice for horse owners
•appreciate references to other international
research projects and scientists
•like research summaries
•enjoy reading the research summaries
• enjoy the photos and publication’s layout.
What can we do better? While some readers
are happy with our current format and content,
we’ve had some great ideas from other survey
respondents about what we can do in future issues
to improve Horse Health Lines:
•more research updates about WCVM projects
and research findings
•a regular section for readers’ questions
•include research citations for current and
previous research articles
•contact information for research teams
•more promotion of Horse Health Lines
•articles on holistic health
•make it easier to sign up for the newsletter online
•online search for previous health articles.
Thanks for all of the great ideas — we’ll try our best
to work on introducing some of your suggestions in
future issues of Horse Health Lines. And now, for the
fun part: prizes! We entered the names of everyone
who completed our readership survey in a draw
and here are our lucky winners:
•Pauline Law and Bryan Leverick: copies of the
Merck-Merial Manual for Pet Health
•Margarita Nikolaev: a copy of the Hands on
Horse Care from Horse and Rider.
Of course, if you have any further comments or
questions about Horse Health Lines, you’re always
welcome to contact us. Send an email to hugh.
townsend@usask.ca or sm.ridley@sasktel.net, or
please contact the WCVM Research Office (306966-7453).
Western College of Veterinar y Medicine
15
Sometimes you
have to really
stretch to reach
your goal.
Finding solutions to critical horse health issues is a
lot like grazing for young foals: you won’t achieve
anything unless you really reach for it.
At the Western College of Veterinary Medicine,
our equine researchers aren’t afraid to push the
knowledge boundaries and search for new ways
to improve the health and welfare of your horses.
With the Equine Health Research Fund’s support,
many of our scientists’ investigations have resulted
in new diagnostic tools and therapies that have
enhanced horse health care around the world.
Want to help push us in the right direction?
Donate to the EHRF and we’ll stretch your
dollars to support:
• Innovative horse health research studies
• Specialized training for graduate students
• Educational opportunities for veterinary
students — Western Canada’s future
veterinarians.
Contact the WCVM for more details:
Lisa Green, Development Officer
Western College of Veterinary Medicine
306-966-7450 • lisa.green@usask.ca
www.ehrf.usask.ca
V i s i t H o r s e H e a l t h L i n e s o n l i n e a t w w w. e h r f. u s a s k . c a
Pacific & Prairie Horse Journal readers: If you enjoyed receiving Horse Health Lines, let
us know! Your feedback helps the Western College of Veterinary Medicine evaluate
B.C. horse owners’ interest in receiving more equine research news inside this magazine.
Email wcvm.research@usask.ca or call 306-966-7453.
Want to donate to the Equine Health Research Fund? Just fill out and mail in the EHRF
donor form on the next page. Your contribution will give vital support to WCVM’s equine
health education and research programs. In return, you’ll receive Horse Health Lines
twice a year!
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