Horse Owners Warned About Blister Beetle Toxicity in Goat

Horse Owners Warned About Blister Beetle Toxicity in Goat

Pedro, a 6-year-old Nubian goat, spent six days in the clinic recovering from cantharidin intoxication.

Photo: University of California, Davis, School of Veterinary Medicine

University of California, Davis (UC Davis), veterinarians recently encountered an uncommon California case of blister beetle toxicity in a goat. Now, they’re urging horse owners to check alfalfa carefully for beetles to prevent additional cases from developing.

Pedro, a 6-year-old male Nubian goat, was showing abnormal health signs that concerned his owners—he was recumbent (unable to rise), bloated, and in discomfort. His owners called their veterinarian, who found him to be severely dehydrated and suggested they bring him to the UC Davis veterinary hospital.

Once at UC Davis, the Livestock Medicine and Surgery Service performed a thorough physical examination on Pedro. His heart and respiratory rates were elevated, he was in severe abdominal discomfort with a fluid- and gas-distended rumen (a ruminant’s first stomach, which receives food or cud from the esophagus, partly digests it with the aid of bacteria, and passes it to the reticulum for further digestion), and in hypovolemic shock. He also displayed signs of an acute kidney injury.

The livestock specialists presumptively treated him for a suspected upset gastrointestinal issue and for his severe dehydration, while awaiting preliminary laboratory results of his blood and urine. His treatments included a rumen lavage, activated charcoal administration, intensive intravenous fluid therapy, pain medication and antibiotic administration, rumen transfaunations (transferring a broad spectrum of microorganisms from a healthy donor animal’s rumen to a sick recipient’s rumen), and gastroprotectant administration. Veterinarians also placed Pedro in a sling during the first days of recumbency and treated him with acupuncture.

Pedro’s condition improved after three days of treatment. He was comfortable enough to walk again and started to regain his appetite. His owners visited him daily and were able to take him home after six days of hospitalization.

Pedro’s final laboratory results confirmed a case of cantharidin intoxication. The blister beetle, which is common in other parts of the United States, but not as prevalent in California, produces the toxin as a defensive secretion. Blister beetles feed on alfalfa bloom and can be found in some livestock feed. Alfalfa harvesting can crush the stalk, but also crush any beetles present, causing them to release the cantharidin inside them. Just a few beetles can be lethal to livestock, including horses, with a fatality rate estimated at greater than 50%.

After hearing the lab results, Pedro’s owners immediately removed the alfalfa feed and quarantined it. They discovered one beetle in the remainder of the alfalfa hay and submitted it to UC Davis’ California Animal Health and Food Safety Laboratory for further testing.

Blister beetle toxicity is commonly diagnosed in horses after consumption of contaminated alfalfa hay, but reports in ruminants are rare. Horse and livestock owners are encouraged to check alfalfa for the presence of blister beetles, and to watch animals closely for clinical signs of cantharidin intoxication. In horses, these can include colic; diarrhea; elevated temperature, heart rate, and respiration rate; and frequent urination.

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