April Newsletter
April 2012
Volume 2, Issue 1
Roaring Brook Veterinary Service, Lindsey Peck DVM www.roaringbrookveterinaryservice.com
News:
I hope everyone is enjoying this amazing spring weather. With spring in full swing I thought a
review of poisonous plants would be a great topic for this month. I encourage everyone to become
familiar with the plants in your area.
I’d like to remind everyone of the upcoming Annual Equine Clinic held at White Frost Ranch.
This year it will be a collaborated effort with myself and Countryside. Please view the attached flyer
for information.
A clinic with Certified Richard Shrake trainer, Elizabeth Hodge, is in the works for May. She trains
horses and riders using Resistance Free Methods. Liz is a Morrisville College graduate of Equine
Sciences where she worked under well-known trainer Spike Holmes. For more information on Liz and
her training methods please view the website http://www.eastedgeranch.com . I would appreciate
feedback on date, interest and if there are any areas of training you would like covered. If there is
no interest, we will not do the clinic at this time.
Poisonous Plants
Red Maple
The bark of red maples is smooth and grayish. The twigs are reddish brown. The fresh leaves are considered
relatively safe, but wilted and fallen leaves can be toxic--but tasty, to horses. The toxins affect the red blood
cells. Three pounds of ingested red maple leaves is considered lethal.
Leaves can remain toxic for several weeks after they've fallen. Don't dispose of red maple leaves in manure
piles or compost heaps that might be in reach of your horses. Red maple leaves can cause problems if baled
into hay. Red maples grow throughout eastern United States and Canada.
Symptoms of red maple poisoning are:
 depression
 dark brown urine
 rapid pulse
 increased respiration
 coma
Oak (Quercus Spp) Poisoning by oak is usually seasonal, being most common in spring
when the young buds or leaves are eaten and the autumn when the acorns are eaten. Oak
leaves and acorns contain tannic acid which is poisonous to horses and though eating a
small number of leaves or acorns is almost certainly harmless, they can also be addictive,
and once a horse has acquired a taste for them they can actively search them out. Also
some animals seem to be more susceptible to oak poisoning than others with individual
animals having different levels of tolerance. Oak poisoning causes gastroenteritis and kidney damage.
Symptoms include:
 lack of appetite
 staring coat
 constipation followed by diarrhea which may be bloodstained
 colic
 depression
 blood in urine or dark
There is no antidote. The horse is treated with drugs to reduce the pain and control the diarrhea, antibiotics may be prescribed.
Prevention: In general it is best to restrict the access of horses to acorns, particularly if other food is scarce, or else pick up the fallen
acorns at least once a day - although this method is time-consuming and less effective as most horses will still find some. The best
thing to do is fence off oak trees - either permanently or with electric fencing.
Brackenfern
Bracken fern is very common, growing along roadsides, in fields, in light bush areas and even gardens. In the
spring 'fiddleheads' unfurl into triangular fronds up to 3ft (1m) high. Bracken fern dried and baled into hay is
still toxic. The roots are said to be five times more poisonous than the fronds. If a horse eats a large quantity
of this fern the toxins can cause a Vitamin B1 deficiency.
The toxin in brackenfern is thiaminase, an enzyme that destroys thiamine (vitamin B1). The horse then
essentially suffers from a vitamin deficiency of thiamine, which causes myelin degeneration of peripheral
nerves (a loss of the fatty insulation layer to nerves that primarily control muscles). Poisoning can occur at any time of year, but is
more likely in the late summer between August and October when other forages are scarce and the level of thiaminase is at its peak.
Bracken is not considered palatable, but horses will eat it if no other forage is available, or they will consume it in hay or bedding,
where it remains toxic. Some horses are believed to acquire a taste for it, and these horses will consume it even if other forages are
available.
First signs include:
In the advanced stages the horse may experience:
 weight loss
 poor co-ordination
 staring coat
 restlessness
 constipation
 severe muscle tremors
 slow pulse
 gait abnormalities
 tucked up and/or hollow appearance
 difficulty in moving and turning during exercise
 staggering (bracken staggers)
 raised pulse and heart rate
 convulsions
 unable to rise
The syndrome runs its course, with death occurring within 2 to 10 days of the onset of signs. Horses can be treated if caught in time. If
recognized early, symptoms can be reversed with daily injections of vitamin B1 for two weeks.
Buttercups: (Ranunculaceae family) Leafy green plants that support stems bearing five to seven
yellow, cup-like flowers. Frequently found in horse grazed pasture. Buttercups are potentially
poisonous because they contain a compound called protoanemonin, which is a powerful irritant,
causing inflammation or ulceration of the mouth, often with sorenes, increased salivation and
sometimes colic. Ingestion of any part of the plant causes protracted, bloody diarrhea and severe blistering of the mucous membranes
lining the entire gastrointestinal tract. However this usually causes the horse to stop eating which makes this condition self-limiting,
although it is always advisable to contact your vet if you are concerned. After a hard frost or dried in hay buttercups are no longer
toxic.
Buttercups may cause:
 irritation of the mouth area
 colic like symptoms
 diarrhea
Nightshades: A relative of the Tomato plant, Nightshades have triangular stems that bear
thin, oval leaves and small yellow, red or black fruit that resemble tomatoes. Gastrointestinal
protectants tend to ease symptoms. Deadly nightshade likes sandy soil and thrives even in dry
conditions. It has a white star shaped flower and the fruit looks like a large black current. All
parts of this plant are toxic to humans and pets. Nightshades can be difficult to eradicate.
Horses are unlikely to eat nightshade or any other toxic plant unless there is no
other feed available or it is baled into the hay and eaten accidentally.
Signs of nightshade poisoning may include:
 colic like symptoms
 loss of muscle control
 disorientation
 dilated pupils
 death
Lamb's Quarters and Pigweed:
Under certain adverse environmental conditions (drought) many weed and crop plants
accumulate nitrate to potentially toxic concentrations. Nitrate-accumulating weeds include
pigweed (Amaranthus spp.) and lambsquarter (Chenopodium spp.).
Pigweed can be very toxic if eaten in large quantities. Horses are unlikely to eat this plant
unless there is no other food available. This weed seems to grow everywhere--from pastures to
vegetable gardens, roadsides to barnyards. It is still toxic if dried and baled into hay. Pigweed,
and its relative lamb's quarters can cause kidney failure. Other symptoms of pigweed ingestion
may include:




respiratory distress
weakness
lack of coordination
coma
Milkweed: Tall stems that ooze milky sap produce pods containing silky, hair-encased
seeds. Prevalent throughout North America in dry, waste areas and along roadsides,
milkweed causes staggering, rapid and weak pulse, coma and death within hours of
ingestion. Sedatives, laxatives and intravenous fluids might ease symptoms.
Milkweed is a very common pasture plant. Elliptical shaped leave branch off of a central
stem. When any part of the plant is torn it will ooze a white, sticky sap. The flowers
grow in a ball shaped cluster and when in full bloom are a lavender color. The pods
develop to about 3" and in fall split open to release brown seeds that float through the air on downy fibers. All
parts of the plant are toxic. Living and dried plants (accidentally baled into hay) are toxic. Like most toxic
plants horses will avoid milkweed unless they have no other food source. Signs of milkweed poisoning are:
 loss of appetite
 loss of muscular control
 constipation
 spasming
 drooling
 rapid and weak pulse
 excitable
 respiratory paralysis
 difficult breathing
 rarely fatal
Lily of the Valley
This common garden plant is toxic to humans and pets, including horses. Lily of the Valley is unlikely to be
growing in a pasture. It could be accidentally ingested if someone were to throw garden clippings close to a
fence line where curious horses might be able to reach. Garden and lawn clippings should be disposed of out
of reach of horses.
St John's Wort (Hypericum perforatum) Found in grassland, hedges and open woods. This plant causes
photosensitation in areas of unpigmented skin, so that when exposed to sunlight they become red and irritated
which leads to rubbing and possible infection. When dried this plant loses 80% of its toxicity but can still be
dangerous when baled in hay.
Azalea or Rhododendron: Perennial shrubs that have tough, glossy, evergreen leaves and produce large, showy
flowers with five white, pink or red petals. Toxin causes gastric and cardiac distress. Within six hours of ingestion,
a horse can appear colicky and have tremors, along with cardiac arrhythmia. If enough of the plant is ingested, the
horse could collapse and die. Treat with supportive therapy