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The potato plant (Solanum tuberosum) is potentially poisonous to horses because it belongs to the perennial nightshade family, one of the most toxic types of wild plants to grow in pastures across the United States. Like the potato, eggplant, peppers and tomatoes are parts of the nightshade family, and considered to be potentially toxic for equine and cattle. While many horse owners claim that bounties from a summer garden are innocuous sources of nutrition, others whose horses have suffered substantial gastro-intestinal distress after ingestion beg to differ. Erring on the side of caution when it comes to potato plant poisoning in horses is likely the best choice. The amount of the potato plant ingested, of course, is the most important variable when considering the prognosis for the horse.
High dosages lead to significant poisonings. In high concentrations, horses experience stomach upset, cramping, labored respiration, colic, ataxia, excessive thirst and in very rare cases, death within hours or days. Since the glycoalkaloids disturb the healthy ratio of cell membranes in the intestinal walls, a long-term inflammatory response may lead to chronic conditions such as inflammatory bowel disease.
Thankfully, all members of nightshade are typically unpalatable to horses. Due to the acrid taste, a horse will sample the plant, but move on to better options. A healthy, well-fed horse with ample grazing will ignore noxious plants and weeds in the pasture. During drought or other times when food is scarce, horses may resort to eating poisonous plants. To avoid such instances, pasture management is recommended. Walk the perimeters and watch for any fast-growing, invasive weeds. Horses may also accidently ingest pieces of toxic plants if mixed with their usual hay and feed. It is recommended that horse owners occasionally test hay inspected for contamination. Of course, if you suspect a poisoning, see a veterinarian as soon as possible. Bring samples of suspect plants for identification.
Alkaloids, the chemical compounds found within the potato, may cause toxicity in horses when consumed in large amounts.
Symptoms of potato poisoning depend upon the dosage of toxins.
Most cases will present with:
More severe cases may present with:
If the horse consumes a small amount of the potato plant, or eats a potato (called the “tuber”), a debilitating poisoning is unlikely. However, making sure that your horse has a plentiful supply of nutritious feed or plenty of green pasture to graze, eradicates such concerns.
For the purpose of this health guide, the word potato is used interchangeably with potato plant. The actual plant, an herbaceous perennial, grows to heights of two to three feet, and puts forth pink, white, and purple flowers with yellow stamens. All parts of the plant are potentially poisonous to horses. The leaves and skins of potato “tubers” (the edible part) may turn toxic when exposed to too much light during the growth period.
The toxic compounds within the potato are called glycoalkaloids (chaconine,solanine), and in proper concentrations are considered natural toxins. Potato poisoning in horses only occurs when a horse is fed a large amount of potatoes, which are sometimes viewed by farmers as cheap and filling feed. Such feedings, however, are dangerous because horses are vulnerable to alkaloids, chemical compounds found within the potato and other members of the nightshade family.
Plant poisoning in its milder form is difficult to diagnose due to its having generalized symptoms. Gastrointestinal symptoms will resemble a wide range of conditions. In its most severe forms, diagnosis may occur post-mortem after sudden death. Veterinarians may also recognize symptoms due to repeated regional poisonings.
Signs of poisoning vary among horses.The veterinarian will discuss the clinical signs with you, along with recent medical history, deworming schedule, and typical daily diet. In order to rule out possible underlying illnesses, the veterinarian may suggest blood tests, a urinalysis, and an evaluation of a fecal sample. If you witnessed the ingestion of the plant, or have seen an area heavily grazed, point this out to the veterinarian. It is very helpful to show the veterinarian plant samples.
In most cases, the horse can recover from an acute bout of potato poisoning. In cases of chronic consumption or severe toxicity, prognosis is poor. If overcome, the treatment will focus on flushing any remaining toxicity from the horse’s system. Possible treatments include a diuretic, extra fluids, and activated charcoal. Making the horse comfortable is a priority, so medication to treat stomach symptoms such as nausea may be given. The veterinarian will advise that you keep your horse stalled in a quiet safe area as he recovers.
A poisoned horse may never return to full levels of performance, however proper diet and care will enable the horse quality of life. Your veterinarian will help you to keep the horse comfortable as it recovers from the poisoning. The best treatment is prevention. Pasture maintenance, awareness of plants, and the provision of an adequate diet are the best ways to keep your horse safe from toxic plants.
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