37
2015
Talking Horses
The newsletter with news, views and practical advice
From the
editor…
In this issue...
It was great to meet so many of you as readers of our newsletters at Equitana 2014.
The Special Equitana Issue #36 was a preliminary guide to looking after horses in hot weather.
You may wish to obtain a back copy by emailing newsletters@kohnkesown.com or logging onto
www.kohnkesown.com to download a copy. We can email you a more detailed Seasonal Alert on
Summer Heat Stress
We also provided handy guidelines on keeping heavily pregnant mares cool
during the hot weather in Talking Breeding #13 published on 12th January
2015. A heavily pregnant mare has a uterine arterial flow of
1,850 litres/minute, or 18.5 times that of a non-pregnant mare!
No wonder they sweat more heavily under hot conditions.
* Locking Stifles
* Navicular Syndrome
* Mould in feeds
Plus handy hints and lots more!
Use a Poly-woven Chaff Bag to Dampen Hay
You can dampen hay by spraying it with clean water and placing it in a
poly-woven chaff bag for 10-15 minutes. You can then carry the dampened hay
to your horse in the bag to reduce leaf loss and mess on your clothes.
Avoid using a hessian bag, as with repeated use, mould can buildup in the natural flax fibres and it can contaminate the hay if it is not
consumed within a few hours. Turn the poly-woven bag inside out once a
week to rinse off any leaves or plant debris to reduce the risk of
mould growth.
Handy Hint 1
In this issue, we discuss ‘locking stifles’ (also referred to as Upward
Fixation of the Patella), as well as provide an updated review on navicular
syndrome and a short note on moulds in feed. For those who have been caught up in bush
fires, we have a new ‘Seasonal Alert’ available on managing horses and donkeys following
Check for Mould in Hay
a bushfire. Again, you may wish to obtain it as a handy guideline by emailing
Wet conditions during harvest and baling of grass with a moisture
newsletters@kohnkesown.com or download it from our website. A number
content above 14% (stored hay should ideally contain 10-12% moisture
of readers have put it up in their tack room.
to prevent mould growth) increases the risk of mould growth which gives it
a ‘musty’, ‘fumy’ odour and matted whitish internal appearance when the
bale is opened to feed out. Mouldy hay can cause colic, infertility, abortion
All the best,
in pregnant mares, ‘hay fever’ and airway disease, as well as retard
growth and lead to liver and brain damage. Here’s a simple way to check for
mould in hay. Take a handful of suspect hay, lightly dampen it with cool, boiled water.
BVSc. RDA
Using boiled sterile water to dampen it is important to minimise mould contamination even
in rain water and mould-inhibiting chlorine in tap water. Place the sample in a
Did You Know That...
new, clear plastic bag which has at least 3-4 times the sample in volume. Place
in a well-lighted warm place in the stable. Check the hay morning and evening
The horse has the largest eye of all land mammals. The eyeball size is
for signs of dark discolouration or white mould filaments (hair-like projections)
largest and most prominent in faster gaited horses. The eyes are positioned
on the hay. Mould should develop within 12-36 hours if it is in a high enough
towards the front on the sides of the head, giving a horse an approximately
concentration to cause side effects when fed to horses. If you are concerned
350o field of vision. This is made up of a forward arc of vision of 65o
about mould in a batch of hay or grain, contact Agrifood Feed Testing Laboratory
binocular vision (using both eyes to the front) and 285o of monocular vision
on 1800 801 312 in Werribee Victoria (www.agrifood.com.au) and arrange to
to the sides and rear, with each eye viewing independently. The horse has
send a sample for mould and harmful mycotoxin identification. For full details,
a ‘blind spot’ extending 40-60cm in front of its nose and also a blind zone of
email newsletters@kohnkesown.com for a free fact sheet or log onto
vision behind its head and over the tail when it is looking forward or to the
www.kohnkesown.com to download a fact sheet on ‘Mould in Feed’.
side without moving its head. Horses have a ‘visual streak’ on their retina,
which has concentrated receptors to sense movement, which is used to
New First Aid Book
detect approaching predators and determine the height of jumps etc.
A new book ‘First Response’ by Australian Amanda Edwards, a
Horses have ‘dichromic’ colour vision. Humans have’ trichromic’ or a near full
professional emergency nurse and horse owner, was released at Equitana
colour spectrum vision. Horses can detect blue and green colour, but not red,
2014. The 200 page book provides excellent and practical advice on First
similar to a red-green colour blind human. Horses can see a 2 colour jumping
Aid and Emergency Care of injured and sick horses. It is written to provide
rail more clearly than a single colour white rail, preferably with white and
clear and simple guidelines in case of emergency and complements your own
black, blue or green bands. They cannot see red bands on a jumping rail,
vet’s advice and attendance. Amanda also manages the Equine Care Clinic,
so avoid jumping rails which are painted red as they appear black and may
providing workshops, care of injured horses and first aid supplies. Her website
blend into the arena surface colour or the distant background. Offer a green
is www.equinecareclinic.com and email amandaequinecareclinic@gmail.com
apple rather than a red apple, as to a horse, a red apple appears black. Cut
This book is a very worthy addition to your horse book library and handy
a red apple into pieces so that the horse can recognise the odour of the fruit.
to have in the tack room or feed room in case of colic, severe lacerations,
With domestication, horses usually become more ‘near’ sighted to enable
laminitis or any of the problems that can happen to a horse!
them to focus on close up objects, whilst in the wild, horses are usually more
We pass on our best wishes for 2015.
Handy Hint 2
Dr John Kohnke
‘far’ sighted to help them see approaching predators in the distance.
Reference: en.wikipedia.org/wiki/Equine vision
Free call: 1800 112 227 - Free fax: 1800 112 228
Website: www.kohnkesown.com
Email: info@kohnkesown.com
Address: PO Box 3234, Rouse Hill, NSW, 2155
© Copyright 2015 John Kohnke Products
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Talking Horses
Equestrian Issue 37 2015
Locking Stifles a multi-cause condition
Handy Hint 3
Locking stifles (also known as upward fixation of the patella or patella luxation)
Avoid Breeding Mares and
is relatively common. The patella in the horse is equivalent to the kneecap in
Stallions with Inherited Patella Luxation
humans. The patella is held in a groove in front of the stifle joint to act as
It has been observed, and confirmed by X-rays angled across the
a ‘pulley’ for an extensor tendon which passes over the stifle on its way
front border of the stifle to image the inner femoral condyle, that individual
to the lower limb. It can become loose in the groove and slip over the
horses or ponies may have less well formed and prominent femoral condyle
ridges. As the condition appears to be a recessive gene in certain bloodlines,
inside edge of the femur to become displaced on the inner border of the
it is best not to breed a mare or stallion with a history of patella luxation. It
stifle, virtually preventing the stifle from bending and it ‘locks’ into a fixed
is recommended to have the femoral condyles X-rayed to confirm the
position. The only way to ‘unlock’ the stifle is to push the animal to take one
genetic abnormality. Stallions should be gelded to prevent
backward step, which straightens the stifle and enables the tendon and patella
them passing the weakness on to future
to ‘pop back’ into its normal position.
generations.
The underlying causes
There are 5 main causes of patella displacement in horses.
Genetic Tendency
It has been observed that certain bloodlines of horses have a
higher incidence due to inherited reasons. Some bloodlines
have smaller ‘condyle ridges’ on the inside (medial) edge of
their femur bones - a structural development problem which
can occur in some pony breeds and minis. This lower medial
ridge allows the patella to ‘slip’ over the inside edge of its
groove in front of the stifle as the animal slightly rotates
its leg when getting up when the patella is held less taut in
its femoral groove. Some lines of horses and ponies have a
tendency towards upright conformation of the hind limbs
and this predisposes the offspring to ‘locking patella’.
Strain of the Stifle Joint
Checking the Angle of the Hind Hooves
The front angle of the hoof wall on the hind limbs should be more upright compared to the
corresponding slope of the front hooves, with a shorter toe and higher heels. A long toe, low
hind heel hoof shape increases the risk of stifle lock because the stifle joint is angled back in a
more relaxed position when the horse is standing, allowing the patella to be ‘loose’ within the
stifle joint. The slope of the coronary band can be checked by placing the end of a piece of
string on the coronary band on the back of the heel and then running it parallel to the slope of
the coronary band to determine
where it intersects on the front
limb.
Line A: Optimum hind limb
coronary angle, with the string
line intersecting at the back of
the knee, or no higher than mid
way between the knee and elbow
on the front limb.
C
B
It has been documented that sprains within the stifle joint
Lines B & C: Lines intersect
can stretch the internal stifle ligaments (cruciate ligaments)
A
too high, indicating that the
or stretch the patella flexor tendon. These types of injuries
coronary angle of the hind
Front Hoof
might be the result of slipping when getting up in a stable
hooves is too high, because the Angle
with a slippery wet floor, especially after being cast against
toes are too long and the heels
Back Hoof
a wall, slipping over when galloping around in a wet, muddy
are too low.
Angle
paddock or when falling down in a float during transport.
This can result in the patella becoming ‘loose’ within its
Long Hind Toes
groove and if the tibia (our shin bone) is unstable due to cruciate ligament
It is well known that excessive toe length on the hind legs, combined with low
sprain, the patella may slip to the inside of the stifle and ‘lock’.
heel conformation, is a common cause of locking patella. This is due to the
Low Selenium Diets
mechanical effect of the long toes and low heels, which results in the hock
Investigation into an unusually high number of locking patella, both single
being positioned more upright and the stifle joint is less angled, leaving the
and both limbs locking, in northern Tasmania which affected growing pony
patella unstable in the femoral groove of one or both stifle joints. Many owners
breeds and minis, linked soil deficiencies of the trace element selenium with
report that the incidence of patella locking is reduced following each time
the regional incidence of the problem. Many areas of Australia where high
the hind hooves are shortened, but that the problem returns as the toes grow
rainfall or a sand-dune base is reclaimed land, have selenium deficient soils.
longer towards the end of the regular 6 week hoof trim.
Besides increasing the risk of locking patella in young growing horses and
Poor Muscle Development
ponies, low selenium levels in pasture, grain and hay grown on areas with a
Many resting, grazing or show horses do not have strong hindquarter muscle
soil deficiency, can increase the risk of poor muscle development and muscle
development. Once a horse is in work, the muscles respond to exercise and
weakness (referred to as ‘White Muscle Disease’ in severe cases) and abnormal
the increased muscle tension and strength helps reduce the risk of a ‘locking’
joint cartilage and tendon development in growing horses or adult horses over
patella. If a horse continues to suffer from a ‘locking’ patella after trimming
an extended time on a low selenium diet.
the hind toes and supplementing with selenium, then it is best to hand walk
or trot on a loose lead up at 10° slope for 1 km twice weekly to stimulate hind
Supplement with Selenium in
limb muscle development which may help reduce patella locking.
Young, Growing Horses
Rapid Growth Spurts
Supplementation with selenium may be helpful to avoid ‘locking’
patella in young horses and ponies. A supplement, such as Kohnke’s
Own Cell-Grow® is especially formulated to meet the needs of growing
horses and ponies, up to about 2 years of age. It contains selenium in
organic yeast form, which is better absorbed compared to chemical forms of
sodium selenite or sodium selenate in most prepared feeds and supplements.
After 2 years of age, daily supplementation with Kohnke’s Own CellProvide® or Kohnke’s Own Cell-Vital, will help provide adequate
selenium to correct low or inadequate intake from pasture and hay based
diets. It is an important daily supplement which
should be fed to horses and ponies grazing
on areas known to have selenium
deficient soils.
It is not uncommon for young Warmbloods in particular, and Thoroughbred
yearlings to develop ‘clicking’ and ‘locking’ patella if they have a growth spurt
as a result of increased energy intake on good pasture or high energy hard feed,
or ‘catch up’ growth after illness or an injury. If it is suspected, then cutting
back the energy intake and providing a balanced calcium, trace-mineral and
vitamin supplement for growing horses or ponies, such as Kohnke’s Own®
Cell-Grow®, is recommended.
Normally the growth plate enlargement of the stifle joint bones returns to
normal dimensions within 4-6 weeks and the ‘clicking’ sound at the walk and
the patella locking ceases.
Handy Hint 4
Talking Horses
Equestrian Issue 37 2015
Navicular Syndrome
Navicular disease is a common bilateral lameness that has been recognised in
athletic horses as a cause of progressive lameness, primarily in the front of
hooves, for over 300 years. It is caused by the slow internal degeneration and
decalcification of the navicular bone, also referred to as the distal sesamoid
bone. The navicular bone is a small bone about the size of a human small
finger bone which acts as a pulley embedded in the Deep Digital Flexor
Tendon (DDFT) as it traverses the coffin joint in the rear of a horse’s hoof.
It is a bone which supports weight and is subjected to concussion in its role
as a pulley to protect the (DDFT). Navicular degeneration is not a disease as
such, but rather a progressive change to the navicular apparatus, which is now
referred to as ‘navicular syndrome’ or more correctly ‘caudal hoof pain’.
Diagnosis of Navicular Syndrome
Symptoms include a progressive heel lameness, ‘proppy or choppy’ gait, toe
stumbling, ‘tied-up in the shoulder’ type movement, excess wearing of the toes
and upright heels with deep frog grooves (sulci) due to contracted heels as a
horse lands on its toes with minimal heel ground contact as a result of caudal
hoof pain. Nerve blocks to localise the area of pain, X-rays and the newer
technologies of nuclear scintigraphy, MRI and CECT under general anaesthesia
provide a more accurate diagnosis and assessment of the structural damage
within the DDFT and navicular flexor surface compared to previous diagnostic
techniques, which relied mostly on nerve blocks and X-rays.
Treatment and Management
Position of the Navicular Bone in the Foot
It is important to evaluate the horse’s breed, history, exercise demand, age,
conformation and any overweight condition which adds extra weight loading.
These factors will be considered together as important criteria in managing
caudal hoof pain. A number of shoeing techniques, including rolled toes to
increase break-over, wedging to elevate the heels and egg bar shoes, may be
used to give relief and restore normal movement. Vasodilating drugs, such as
isoxoprine, have been shown to be of benefit in early cases. Barefoot trimming
has been widely advocated to balance the hooves with many reports of success
in early cases.
Short pastern bone
Coffin joint
Pedal bone
Deep flexor tendon
New drugs in the bisphosphonate class have been shown to be of benefit in
re-mineralising bone and reducing navicular lameness after a single injection.
The product Tildren® (CEVA) is now available in Australia for use in
horses with navicular syndrome and bone spavin. In the USA, a similar
bisphosphonate, marketed as Osphos®, has shown a 74.7% reduction in
lameness scores in navicular affected horses at 56 days after a single injection.
Consult your vet for advice.
Navicular bone
(encased in deep flexor tendon, which results in a
naturally poor blood supply and a large amount of
concussion during exercise)
De-nerving the rear of the hoof in chronic cases is not permitted in
competition horses and surgically cutting the distal sesamoid ligaments or check
ligaments has been carried out with mixed success. Consult your vet for advice.
Reference: D Rodgerson DVM (2013) Aust. Equ. Veterinarian 32(4). 41-44.
Underlying Causes
The exact underlying cause is unknown, but various theories have been
proposed. The original theory developed in the USA was related to concussion
and resulting bursitis in horses working on hard ground, police horses
on paved roads or reining and jumping horses, combined with upright
conformation, heavy shoulders, ‘pinched heels’ and long term poor farriery
techniques. It is considered to be an inherited problem in small-footed horses,
especially Quarter Horses. Researchers in Denmark have proposed that
increased pressure between the DDFT and the navicular surface of the coffin
joint is the cause of degenerative cartilage damage (osteoarthritis), which leads
to coffin joint lameness and caudal hoof pain.
Over 30 years ago, navicular degeneration was linked to clotting of blood
within the small vessels originating in the DDFT, causing poor blood supply
and demineralisation, consistent with internal ‘lolly-popping’ of the vascular
channels on the back border of the navicular bone. These can be seen on an
X-ray and were thought to be the bony degeneration associated with ‘ischaemia’
or poor blood supply to the rear border of the small bone.
Recent studies using Magnetic Resonance Imaging (MRI) and Contrast
Enhanced Computer Tomography (CECT) have localised vascular and other
degenerative changes to soft tissue structures in the heel of the hoof. These
are considered to lead to internal fluid swelling (oedema) within the navicular
bone and continued concussion results in tears within the embedding fibres of
the DDFT. This is now considered to be the cause of ‘caudal hoof pain’ (pain
in the rear of the hoof), with typical symptoms of navicular syndrome.
an up-to-date review
Please Note: A detailed fact sheet on ‘Navicular Syndrome’ is available
from newsletters@kohnkesown.com
Handy Hint 5
Managing Navicular Syndrome
Recent reports suggest that the combination of
corrective barefoot trimming or shoeing with rolled toes
and egg-bar shoes (with or without raised heels), combined with daily
supplementation of a joint preparation containing glucosamine, manganese,
vitamin C and other cartilage ‘foods’, such as Kohnke’s Own® Nutricart®,
is successful in relieving the progressive deterioration caused by navicular
overloading and developing fibro-cartilage collapse in ageing
equestrian horses.
Success of Corrective Trimming
and Shoeing
Corrective barefoot trimming alone is successful in about 50% of hacks
and lightly worked horses. Using an egg-bar shoe to extend, expand and
support the forelimb heels, is effective in about 33% of early navicular cases.
However, ensure that the hind toes are kept short and squared off to
prevent ‘forging’ and risk of ‘heel chop’ during
workouts if egg-bar shoes are fitted.
Handy Hint 6
Benefits of Barefoot Trimming (BFT)
Did You Know That...
A hereditary predisposition to navicular syndrome, related to the shape of the
navicular bone and thickness of the fibro-cartilage layer at its articulation within the
coffin joint, has been identified in Warmbloods. Offspring of stallions with a concave
navicular lower border and a thin cartilage covering had a higher risk of developing
navicular syndrome. Earlier studies suggested a 35% risk of inherited navicular
syndrome from affected stallions, compared to 5% for sound stallions.
Barefoot trimming is now widely advocated to restore
proper symmetry and balance to the front hooves of horses
with navicular syndrome. It may help to improve the internal blood
flow and reduce compression loading on the heels and navicular
structures. It has proven to be effective for early navicular problems,
and it is worthwhile to carry out regular
barefoot trimming by a trained BFT
professional on a regular monthly
program.
Handy Hint 7
Talking Horses
Equestrian Issue 37 2015
Moulds in Feed A Growing Problem
Grains and hays can be contaminated with fungal organisms or moulds during
harvest, storage and processing under damp or humid conditions which are
Minimising the Risk of Mould Contamination
favourable to their growth. Perennial Ryegrass pasture can contain
You can adopt a number of measures to minimise mould in feeds.
an endotoxin produced by endophyte fungi in late summer and
Maintain
grain
and hay moisture content below 12% to limit mould growth. Some
1.
autumn, triggering ‘ryegrass staggers’ in horses, sheep and
molasses sweet feeds contain 15-18% moisture in sealed bags which may facilitate mould
cattle.
Moulds present in hay and hard feed can affect the
health and performance of breeding, growing
and working horses in a variety of ways. Fungal
organisms can be inhaled from mouldy or
‘musty’ hay, triggering an allergic asthma-like
effect on the lower airways, with inflammation
and constriction of airway capacity. This can
have a direct effect on airway function, reducing
oxygen uptake and ultimate performance.
growth and the in-built anti-mould agents may not be effective. Always check bagged feeds for a
mouldy odour, especially those nearing their expiry date, as well as mould in the bottom of the bag
or on the underside of bales of hay stored on damp ground, especially following wet, humid weather.
2. Test any suspect feed, particularly darkened or black tipped grains or ‘fumy’ hay for presence of
mycotoxins. These tests can be carried out by the Agrifood Feed Test Laboratory at Werribee, Victoria.
<www.feedtest.com.au> Phone: 1300 655 474.
3. Generally, properly extruded and dried grains have less risk of mould growth if stored under dry,
aerated conditions.
4. Use buffered mould inhibitors based on natural propionic acid to resist mould growth during
storage of grain. These can be obtained from your feed or produce store (eg Mold-Zap®).
Mould toxins, called mycotoxins, can have adverse
effects on the appetite or the immune system, and in a
breeding mare, reduce fertility, cause abortion and early embryonic
death, as well as retarded growth in young horses.
5. Products, such as Kohnke’s Own® Activ-8™, contain a
special mycotoxin binding yeast to help support
the immune system.
Other feed mould toxins (eg aflatoxins) can be ingested in contaminated feed,
leading to increased risk of harmful damage to the liver and kidneys and
suppression of the immune system.
Handy Hint 8
Store Grains and Hay under Dry Conditions
Wet, cold weather can lead to moisture condensation on the inside of the
It has been estimated that up to 25% of the world’s grain supply is
walls of metal silos, steel 200 litre feed drums and metal feed storage bins in the
now contaminated with mycotoxins. Although some moulds
stable feed room and facilitate mould growth. Always check for dampness, blackening
and a ‘musty’ odour within the layers of grains and chaff touching the metal sides. Store
can be used to produce bread, cheese and antibiotics, recent
bulk grains in poly-woven bags or inner plastic containers/buckets and place them, along with
changes in global weather patterns, with flooding, droughts
bags of chaff, inside the bins to minimise contact with the walls to help avoid the risk of mould
or unseasonal frosts, have increased contamination of animal
contamination. Do not store dampened feed mixes for more than 24 hours. Check the centre
feeds with a variety of harmful mycotoxins.
section of round bales for mould by checking and feeding out the hay in portions rather than
The moisture content during harvest of grains and hays, and
allowing horses to waste hay and risking mould growth in wet weather by
especially in baled hay and stored grain, exceeding 14%, combined
providing hay as ‘self-serve’ in a yard or paddock. Do not store
small hay bales under plastic or metal sheeting as the hay is
with drought stress during the growing period and broken kernels
likely to develop mould on the outer surfaces.
of grains, can all increase the risk of mould growth and mycotoxin
Handy Hint 9
production.
Recent research has highlighted the widespread effects that moulds and their
mycotoxins can have on athletic and breeding performance, with a growing
realisation that mould contamination of hay or grain must be considered as a
cause of poor performance in racing and equestrian horses.
When you need a product to assist joint
health and function in horses, supplement
with Kohnke’s Own Nutricart
Please Note: Separate detailed Fact Sheets on ‘Moulds in Feeds’ #M10 and
‘Ryegrass Staggers’ #S7 are available by emailing newsletters@kohnkesown.
com or by downloading from www.kohnkesown.com
Control Aspergillus spp
Mould in Stables
Handy Hint 10
Inhalation of Aspergillus spp mould in
molassified feed (sweet feeds), hays, shavings and straw
bedding may produce allergic airway disease, which under
humid conditions, can increase the incidence of airway damage
and lung bleeding in racing and eventing horses. It appears that the
allergic response to microscopic mould particles, less than 5-10 microns in
diameter, triggers airway inflammation, rather than a mycotoxin type reaction
in the lower airways and lung air sacs. Keep feed bins and water vessels
clean and remove molasses residues which harbour mould, on a regular
weekly basis. Steam clean or wash down all the feed buckets and walls
of stables with soapy water where molasses is used to sweeten feeds
at regular 10-14 day intervals to control its Aspergillus spp mould,
especially prior to introducing a new horse to the stable. Remove
all cobwebs which can harbour fine dust and mould and
dissipate them into the stable air space.
• The Nutricart formulation has proven its
effectiveness throughout extensive field
trials in both Australia and Overseas.
• Nutricart contains glucosamine
hydrochloride as the major joint cartilage
component.
• Nutricart is complemented with other
nutrients which have a role in cartilage health and function which may
be low or inadequate in common grain, chaff and hay mixes.
• Low Dose - 20g maintenance dose delivering glucosamine and
complementary joint nutrients.
• Highly palatable natural fenugreek flavouring, low dust formulation
with no ‘fishy’ odour.
• Highly economical and effective!
Pack Sizes: 1.2kg (60 x 20g doses) or 4kg (200 x 20g doses)
Disclaimer: The information and recommendations in this newsletter have been presented as a guideline based on the veterinary experience and knowledge of the
author, Dr John Kohnke BVSc RDA. Whilst all care, diligence and years of practical experience have been combined to produce this information, the author/editor,
Dr John Kohnke, accepts no responsibility or liability for unforeseen consequences resulting from the hints and advice given in this newsletter.
The information in this newsletter, or part thereof is copyright. We encourage its use in newsletters and other horse/pony club or association bulletins, provided that
the source of the newsletter is acknowledged as courtesy of the author, Dr. John Kohnke BVSc RDA. The information cannot be used for magazine publication unless
permission is sought from the author by email info@kohnkesown.com prior to publication.
©Copyright 2015