The third emergency of the day was a 2 week old Lincoln lamb, squalling loudly as he was moved onto the blanket-covered table. The little black-and-white faced lamb had presented for a strange hindlimb gait noticed this morning, although he was still able to nurse well. I quickly checked his gum color before listening to his heart and lungs and taking his temperature. His vitals were within normal limits, but he seemed easily spooked and his hindlimbs would intermittently become rigid and stretch out behind him. His umbilicus was healing well, and his tail was in the process of being banded (a method of tail docking that involves placing a rubber band around the tail to cut off blood flow). He was being kept intact since the owner wanted to keep him for breeding.
We placed the little black lamb on the ground to see how he moved. He stood with a base-wide hind stance, but was interested in sniffing us and could walk, albeit with a very short, stabbing gait. The clinician tested for vision and the menace response by waving his hands in front of each eye, and with each hand wave, the lamb would startle backward, enough that he would occasionally collapse in the hind end, his hindlimbs extending rigidly straight out behind him. As we continued watching him, we noticed he would startle with any type of sudden movement or loud sound.
“Well, this sure looks like tetanus…” the clinician said with a vague air of incredulity. This was the first case of tetanus in a sheep he’d ever seen, which was impressive because this guy had worked exclusively with large animals for more than 30 years. But it makes sense—tetanus is one of the diseases protected against by the core Clostridial vaccine which is given to all sheep and goats annually, so the prevalence of tetanus is much, much lower than it used to be.
Tetanus is a disease caused by the toxin produced by the bacterium Clostridium tetani, which is ubiquitously found in the soil and gastrointestinal tracts of animals. This neurotoxin circulates in the blood until it binds to the nerves innervating nearby muscles, causing spasmodic muscle contractions. If the circulating tetanus toxin isn’t bound or continues to be made by an active infection of Clostridium bacteria, then the neurotoxin can move retrograde up the nerves to the spinal cord. Depending on where the infection began, the affected muscles can include the limbs, diaphragm, and jaw muscles. Tetanus is a quickly progressive disease, and animals often die of suffocation within a few hours to days unless treatment is initiated.
So, we gave a shot of antibiotics and another of tetanus antitoxin to the little black Lincoln lamb and sent the owner home with a second dose of each. It was good news that he could still walk and suckle well, but only time would tell if he would respond to treatment and improve. As he headed out the door, I crossed my fingers and wished him good luck.