Case Report Highlights Oak Toxicosis in Cattle at Auburn University

Prior to her admission in late spring, the cow had exhibited signs of distress, including a lack of appetite and inability to rise for two days. Upon evaluation, she was noted to be close to death, with rapid breathing at 44 breaths per minute and a heart rate of 76. Her rectal temperature was below normal at 36 °C, and her bloodwork revealed severe kidney failure with a blood urea nitrogen level of 207 mg/dL, markedly elevated creatinine levels, and abnormal electrolyte measures.

Faced with a grim prognosis, the veterinary team decided to euthanize the cow. A necropsy revealed notable internal findings, including fluid accumulation in the chest and abdomen, alongside severe hemorrhaging in both kidneys. These injuries are typical indicators of oak poisoning, characterized by the damage to renal tubules and the vascular system.

Pathological examination confirmed significant renal damage, affecting roughly 70% of the renal cortex. The lungs revealed signs of acute aspiration pneumonia, but it was deemed an incidental finding due to the cow's critical state. Toxicology testing also identified gallic acid, a breakdown product of oak tannins, confirming oak toxicosis as the cause of death.

Other potential causes of acute kidney injury, such as mycotoxins, insecticides, and other toxic plants, were ruled out based on the cow's history and test results. This case emphasizes that oak leaves, buds, and acorns, particularly those from young plants in spring, pose a serious risk to cattle, as the tannins in these parts of the oak are converted into harmful byproducts in the rumen.

Signs of oak toxicosis can vary, with common symptoms including anorexia, depression, dehydration, and, in severe cases, kidney hemorrhage and renal failure. Notably, this cow did not display the usual gastrointestinal lesions associated with the condition, which makes this case particularly instructive.

There is no specific antidote for oak toxicosis, and prognosis usually depends on the extent of kidney damage. Preventive measures are crucial, especially during drought or poor pasture conditions when cattle may resort to eating oak. Strategies include fencing off oak stands and providing adequate forage to minimize risk.

This case serves as a reminder to cattle producers and veterinarians that oak toxicosis remains a significant threat and should be suspected when a cow presents with acute renal failure, especially if there is a history of exposure to oak trees.

Source: "Acute renal failure in a 4-year-old Angus-cross cow," Journal of the American Veterinary Medical Association, Vol. 264, No. 10. doi: 10.2460/javma.26.02.0125. Case from Auburn University College of Veterinary Medicine.