Featured Case of the Month - "Curious George" Signalment: George is a twenty year old Paint gelding History: George was found at his morning feeding with a severely swollen muzzle. He was normal at bedtime the night before. He had a small amount of blood from both of his nostrils and was uncomfortable but still able to breathe. George's owners brought him into the hospital as soon as they found him. Physical Exam: All of George's vitals were within normal limits. Two small puncture wounds were found on his nose, and he still had a small amount of blood coming from each nostril. Although air was still coming from both nostrils, the flow was decreased. The swelling started at the tip of his muzzle and extended 14 inches toward the back of his head. His throatlatch area was not swollen. Figure 1. "Curious George" on presentation Figure 2. Muzzle, with arrows pointing to puncture wounds Diagnostics: The appearance of George's muzzle was classic for a rattlesnake bite. A Complete Blood Count assesses red blood cell, white blood cell and platelet counts. The snakebite toxin can destroy (hemolyze) red blood cells, causing an anemia. It can also cause clotting problems, which may lead to a low number of platelets. Because the drugs used to treat snakebite horses sometimes have adverse effects on the liver and kidneys, a Biochemistry Panel was run to get baseline values on the function of these and other internal organs. No abnormalities were found on either the CBC or Chemistry profile. Snakebite Disease Process: The most common location for horses to get bit by a rattlesnake is on their nose after investigating the rattle sound. They do also occasionally get bit on their lower limbs and very rarely on their underbelly. The toxin is a mixture of several enzymes and other proteins that cause damage to the surrounding tissues. One of the toxin's properties is to make the local blood vessels leaky, causing tremendous swelling in the area around the bite wounds. The toxin also contains agents that cause hemorrhage and destruction of red blood cells (hemolysis). Usually, these effects are localized to the tissues around the bite wounds, but occasionally the toxin gets distributed systemically. Systemic effects of the toxin are much harder to treat and carry a worse prognosis. Treatment: Horses cannot breathe through their mouth, so they rely on their nasal passages. Because the swelling in George's muzzle could occlude his nasal passages, nasopharyngeal tubes were placed up each nostril to keep the passage to his trachea and lungs open. George was given intravenous corticosteroids (Dexamethasone SP) and non-steroidal anti-inflammatories (Banamine) to reduce the swelling in his muzzle. He was started on antibiotics (Procaine Penicillin G and Gentacin) to help prevent a secondary bacterial infection at the snake bite location. One unit of antivenin was also administered to help prevent further worsening and also to speed the healing process. Because George could not eat or drink, he was put on intravenous fluids to keep him from getting dehydrated. Figure 3. Nasopharyngeal tubes to help keep his airway open Recovery: George's muzzle continued to swell over the course of the day. By midnight, the swelling had reached its peak. The following day, it was determined that he had sufficient airflow to merit removing one tube. His airflow was monitored closely throughout the day, and the following morning, the swelling had decreased enough to pull the other nasopharyngeal tube. Some blue discoloration remained around the bite wounds where the toxin had caused local tissue damage. This tissue would either die and slough away or heal on its own and become pink again. George was able to eat and drink well after pulling the second tube, and he was discharged later that afternoon. Figure 4. Two days after snake bite Figure 5. Blue discoloration on muzzle CLOSE WINDOW Copyright © SWMSC - All Rights Reserved