Few images can rival that of horses grazing freely on lush pastures, yet oak trees produce leaves, buds and acorns which are toxic to horses.

Tannins found in oak buds and acorns can bind with proteins in the digestive system and damage tissues causing what’s known as “acorn poisoning or oak toxicity.”

Tannin

Tannin is a toxic compound found in many plants, such as oak trees. When horses consume oak tree acorns, leaves, bark or branches they become poisoned by tannin. Once in their digestive tracts the toxic tannins cause kidney damage as well as colic symptoms in some horses which may include lack of appetite and weight loss, as well as bloody manure or urine in affected horses.

Horses can also be poisoned by eating the roots of American holly trees (Ilex opaca), which contain toxins that cause stomach ulcers. Other plants that may poison horses include black walnut trees (Nerium oleander), red maples (Acer rubrum) and peach or plum trees (Prunus persica), so their leaves, flowers, fruit and roots should be kept at a distance.

Red Maples

While Acer rubrum (commonly known as swamp or soft maple) trees boast breathtaking red leaves that can be enjoyed for their aesthetic value, they can also be deadly. Containing toxic substances which cause rapid death if consumed in large amounts by horses, especially its leaves and buds which contain chemicals that destroy red blood cells of horses; even older wilted leaves pose as much of a danger as newer leaves due to an increase in intensity over time compared with fresh leaves.

Acorns

While wild animals such as squirrels rely on them for nourishment, acorns should not be fed directly to horses as food sources. Their content of tannic acid and gallic acid may cause severe harm to a horse’s digestive system and kidneys resulting in colic and malaise symptoms for horses as well as constipation, bloat, weight loss and blood in manure or urine as well as fluid accumulation in legs (edema).

Poisonous Oak Trees

As its name implies, poisonous oak (Quercus velutina) trees can be extremely hazardous to horses and can even kill them within 24 hours if enough leaves or buds are eaten by horses. Their poisons mimic those produced by other members of Prunus family trees such as wild cherry and peach which contain cyanide in their leaves when their leaves wilt – thus rendering the poisonous oak even more deadly than usual!

Oak trees in horse pastures should be fenced off to prevent horses from accessing their leaves and acorns, which could potentially cause gastrointestinal or renal damage or colic in horses. If a horse shows any symptoms of acorn toxicity it should be seen by your veterinarian immediately – for best results inspect grazing areas for low-hanging branches or acorns more frequently during autumn when more are eaten by horses than ever. Supplementary feeding with hay will also help minimize risks related to eating too many acorns!