Toxic Plants & Horses

Since it's spring/early summer in most areas, I thought I'd do a post about some toxic plants to horses. I've had one up close and personal with one toxic plant: buttercups. Luckily there are only a few dotting our pasture, but Jetta of course decided to sample them. Most of the time, horses won't eat them because they aren't very palatable, unless of course you have an overgrazed pasture or an idiot horse who is bored and curious.



Mouth ulcers can result from eating toxic plants - this is what
Jetta's sores looked like.

 None of these photos are mine, but show you what to look for and the symptoms of ingestion.



Buttercup - part of the Ranunculus genus.

 Buttercup ingestion causes irritation of the mouth, colic-like symptoms and diarrhea. The one that I experienced is irritation of mouth - Jetta had lesions on either side of her mouth.



Bracken Fern - very common in the NW. Toxic even if it is dried and baled into hay.

Symptoms of bracken fern poisoning may include: loss of coordination, depressed heart rate, arrhythmia, weight loss and eventual death if not promptly treated.



Milkweed - I think most people know that
milkweed is poisonous, but if not, take note!

Signs of milkweed poisoning are: disorientation, loss of muscular control, spasming, rapid and weak pulse and respiratory paralysis. Ingestion is rarely fatal, but still needs immediate veterinarian attention.



Pigweed

Pigweed ingestion can cause kidney failure, as well as respiratory distress, weakness, lack of coordination and coma.



Red Maple is another common toxic plant.

Red Maple's fresh leaves are considered ok. But the fallen and wilted leaves can be toxic. Just three pounds of fallen leaves can be lethal. Also look for these leaves in your hay as they are still toxic when dried. Other symptoms are depression, dark brown urine, rapid pulse, increased respiration and coma .



Azaleas are toxic to all animals - including your dogs!

 Symptoms of azalea poisoning include: excessive salivation, usually green and frothy, muscular weakness, slow heartrate, vision problems, colic and gastrointestinal problems. If left untreated, poisoning by this plant can cause death within a few days.



Cherry (all varieties) and peach, are toxic because they produce cyanide.

Consumption of the leaves from these plants can result in death within minutes if enough are consumed. Other symptoms include: troubled/labored breathing, flared nostrils, loss of control of urination and defecation, lack of coordination, trembling and agitation. Basically, cyanide prevents the absorption of oxygen into the blood stream to horses basically suffocates. The leaves are the most toxic when the plant is stressed or wilted.



Black Walnut

Black walnut isn't actually toxic when ingested. It's toxic when the horse's feet comes into contact with it, such as in shavings, and it causes laminitis. Only 10% of black walnut in your shavings can bring on laminitis and even the nuts falling in the pasture can make the ground toxic.

Oleander is very toxic

Horses don't have to consume very much of Oleander to cause symptoms and any part of the plant is toxic. Luckily this plant is very unpalatable, but it is commonly consumed by horses when accidently included in grass clippings. Symptoms of ingestion include: death within 12-24 hours, labored breathing, profuse sweating, abdominal pain or colic-like symptoms, diarrhea (may or may not be bloody), abnormal heartbeat (either too fast, too slow, or erratic), poor circulation, tremors or shaking and muscle pain and twitching.

These are just a few of the plants that can be toxic to horses, just doing a quick google search will turn up a whole bunch more!
Source: Understanding Horse Nutrition - Poisonous Plants

The best treatment is prevention. We mow our pasture to keep the weeds down. Know where your hay comes from and check for toxic plants in the hay. Make sure that there are no toxic trees in or bordering the pasture. If you suspect that a horse has eaten enough of a plant to cause major physical problems or enough to be fatal, don't hesitate to contact your vet for advice and/or treatment!