Acorn Toxicity

Barry Whitworth, DVM

Area Food/Animal Quality and Health

Specialist for Eastern Oklahoma

With the prolonged drought, most pastures in Oklahoma are in poor condition. With the lack of available forage, animals may go in search of alternative foods. If oak trees are in the pastures, acorns may be a favorite meal for some livestock this fall. This may result in oak poisoning.

Oak (Quercus species) leaves, twigs, buds, and acorns may be toxic to some animals when consumed. Obviously, acorns can be a problem in the fall and green acorns can be more toxic than mature acorns. When acorns form only a small portion of the diet, there are usually no signs of problems. However, consumption of large quantities may result in toxicity. Tannins in the acorns cause the toxicity. The most common tissue damaged by the tannins are the digestive tract and kidneys. Cattle and sheep appear to be more susceptible to toxicity than goats. Other animals such as horses, rabbits, and chickens have succumbed to the toxicity of oak poisoning as well. Interestingly, some individual animals are more tolerable of the toxins and show no ill effects when consuming acorns.

Clinical signs of oak toxicity usually appear a few days after consumption of acorns. Initially, the animals are weak, listless, emaciated, and anorexic. This is followed by ventral edema (swelling of lower parts of the body such as legs, chest, ventral abdomen), urinating large amounts of urine, abdominal pain, and constipation. The animal may pass hard mucus covered fecal material which may change to black tarry or bloody feces as the disease progresses. If the animal is not treated, kidney failure is likely.

A tentative diagnosis of acorn poisoning may be based on clinical signs and access to acorns. Blood tests that indicate kidney disease is another clue to the condition. A necroscopy with examination of tissues for characteristic lesions of the disease is the standard to confirm a diagnosis of oak toxicity.

Treatment of oak toxicity starts with removing the animals from the area where the acorns are located. Those animals displaying signs of the disease should be given fluids to correct dehydration and electrolyte imbalances. Mineral oil and/or activated charcoal may be given to reduce toxin absorption. If animals survive the initial toxicity, they may recover, but it may take several weeks for kidney function to return to normal.

As always, prevention is better than treatment. Producers should be very careful allowing livestock to graze in areas where acorns are present. Livestock should be fed plenty of hay and feed this fall to avoid over consumption of acorns. For those producers who cannot avoid grazing areas with large numbers of oak trees, feeding a grain mixture with 10% to 20% of calcium hydroxide has been successful in preventing problems with acorn poisoning.

Two thousand twenty-two has not been the best year for livestock producers. The drought has produced poor pasture conditions as well as very little hay. On top of those problems, feed costs continue to increase. The last problem a producer needs is a large number of sick cows. For those that graze an area with a large number of oak trees, prevention may be worth the cost this year. At the very least keep a close watch of your animals this fall. Producers wanting more information about oak toxicity, should consult with their local veterinarian or visit with their Oklahoma State University Cooperative Extension County Agriculture Educator.