OSU veterinarians detect organophosphate toxicity in a show goat pair

Wednesday, June 18, 2025

Media Contact: Kinsey Reed | Communications Specialist | 405-744-6740 | kinsey.reed@okstate.edu

At the Oklahoma State University Veterinary Medical Teaching Hospital, clinicians received a call from a referring veterinarian about two 7-month-old wether goats named Last Chance and Tower.

Both were rushed to OSU after a consultation regarding their five-day history of inappetence, diarrhea and elevated liver values of unknown origin.

Last Chance was in worse condition, with the referring veterinarian concerned he might not survive the trip. Tower exhibited similar, but milder, clinical signs. On physical exam, Last Chance presented with coughing, labored breathing, pinpoint pupils, lethargy, muscle tremors, excessive salivation and delayed mentation.

Initial differential diagnoses included pneumonia, coccidiosis and salmonellosis — but the case wasn’t adding up.

Bloodwork from the referring veterinarian showed acute liver damage, high blood cell counts. Still, no clear cause could be identified, and Last Chance had not responded to fluid therapy or treatment. It wasn’t until Dr. Myriam Jimenez, food animal assistant professor, related that the pinpoint pupils and general signalment and bloodwork looked more like an acute toxicity and noticed a strong, unfamiliar odor on the goats' coat, that the breakthrough came.

“The smell of the treatment was very strong,” Jimenez said. “After smelling that, I had an imminent need to call the owner and figure out what it was.”

Initially suspecting pyrethrin toxicity, Jimenez called the owner to see if any treatments had recently been administered. During the conversation, the owner revealed that lice treatment had been applied to all their animals, but no one else displayed any clinical signs, so she did not think it was the cause.

However, while the conversation continued, she expressed that due to limited pen space, Last Chance and Tower had been housed together afterward. After looking into the specific treatment, Jimenez discovered it was an organophosphate. When combined with the clinical signs, this information pointed strongly to organophosphate toxicity as the likely diagnosis.

Organophosphate toxicity is rare in goats but is a serious condition caused by exposure to chemicals like those found in certain lice treatments or for plant pest control. Organophosphates work by inhibiting the enzyme acetylcholinesterase, leading to the accumulation of acetylcholine, which disrupts nerve function. In livestock, symptoms can include pinpoint pupils, excessive salivation, muscle tremors, difficulty breathing and even seizures in severe cases.

In this case, Jimenez said the pinpoint pupils, also known as miotic pupils, a lack of response to light, and elevated liver enzymes were classic signs. The link between the chemical treatment and the symptoms became clearer when it was revealed that the two goats had been housed together, allowing them to lick each other and possibly ingest a toxic dose.

The veterinary team acted quickly once the suspicion of organophosphate toxicity was raised. Atropine, a drug that counteracts the toxic effects of organophosphates, was administered. Last Chance’s symptoms began to improve almost immediately, confirming the diagnosis.

Atropine works by blocking the action of acetylcholine, thus providing immediate relief. However, atropine alone wouldn't be enough to fully reverse the effects. Organophosphate toxicity requires a more specific treatment: pralidoxime (2-PAM), which helps reactivate acetylcholinesterase, allowing the body to break down the accumulated acetylcholine. The challenge, however, was that 2-PAM can be difficult to find, and it needed to be specially ordered.

The team immediately contacted the OSU VTH pharmacy and the goat’s owner. After a detailed discussion, the owner agreed to proceed with the 2-PAM treatment. The drug was delivered promptly, and the treatment began with cautious dosing.

Within hours, Last Chance showed dramatic improvement. He regained the ability to stand and walk, and his symptoms of lethargy and weakness began to subside. While not yet fully recovered, his condition had transformed from life-threatening to stable, thanks to quick thinking and the right treatment.

“Since organophosphate toxicity is rare in food animal species, I hadn't had the opportunity to utilize 2-PAM as a treatment,” said Mandy Lawson, fourth-year veterinary student. “Cases like this are the epitome of a teaching hospital, giving students like me the opportunity to practice the highest caliber of medicine and to gain exposure to treatments that may not be readily available at a rural practice. Those lessons are extremely valuable as we transition out of our clinical year at OSU and into the role of practicing veterinarians — they teach us what to look for and how to know when to refer cases. I can truly say this patient made me a better doctor.”

Throughout this case, Jimenez emphasized the importance of looking at the whole picture — every piece of information from clinical signs to environmental factors. In particular, the strong communication between the clinicians and the owner played a crucial role in solving the mystery. Initially, the owner was hesitant to consider the possibility of toxicity, but the veterinary team’s persistence in obtaining all the details ultimately led to the correct diagnosis.

This experience was invaluable not only for the clinicians but also for the students working on and observing the case. They learned the importance of thorough diagnostic work, especially when symptoms seem inconsistent or unusual.

“This case was a great learning opportunity for students to see that you need to follow your instincts. The knowledge is there, you just have to learn to connect the dots and treat the animal, not the bloodwork,” Jimenez said. “Once we began treating the toxicity, it became clear that relying solely on the bloodwork would have led us to keep him on IV antibiotics longer than necessary. He did very well without them.”

For livestock owners, this case underscores the importance of early recognition of poisoning and immediate intervention, as it can be the difference between life and death. This case also highlights the importance of open communication with your veterinarian. What might seem like a small, insignificant detail — like the lice treatment, the shared pen or the odor of the treatment — could be the missing piece of the puzzle.

“Even if you think a detail is not important, just share it,” Jimenez said. “The answer may be the difference between treating the animal with the appropriate drug promptly versus making an incorrect diagnosis or delaying treatment.”

Last Chance’s recovery was a testament to the power of observation, collaboration and clinical expertise. The successful outcome was made possible by the combined efforts of a dedicated referring veterinarian, a committed owner, skilled technicians, engaged students and the thoughtful contributions of five OSU faculty members. Drs. Jimenez and Shari Kennedy from the food animal medicine and surgery group, along with Drs. Ari Merari and Kelsey Walker from the large animal emergency team, worked closely with students and house officers to discuss the case, determine treatment protocols, administer care and monitor the patient’s response throughout the process.

The case challenged the veterinary team to think creatively and provided an invaluable learning opportunity for all involved.

“In my opinion, cases like Last Chance’s organophosphate toxicity are some of the most rewarding in veterinary medicine,” Lawson said. “They represent a true culmination of the knowledge we gain in veterinary school. From recognizing subtle changes in clinical signs to applying concepts from courses like clinical pathology, pharmacology and food animal techniques, everything comes together.

"His case initially stumped us, but through collaboration, we reached the correct diagnosis and were able to administer effective treatment for a successful outcome.”