Unusual Lesions Seen in Rankin Inlet Caribou Herd

During the late summer and into autumn a problem was observed in caribou in the Rankin Inlet area in Nunavut.  The Ontario/Nunavut regional CCWHC lab received a number of samples of feet and lower legs from some of these animals.  The reports typically described an animal that was limping badly, and was usually in very poor body condition.  Many of these animals also had oral lesions and some had evidence of a parasitic skin infection.

All of the samples received had severe lesions affecting the feet and in some cases infection was into the bone.  Laboratory analysis of the samples isolated a mixture of bacteria, including Fusobacterium necrophorum, a bacteria that may cause the condition commonly known as Necrobacillosis.  In domestic ruminants it is more commonly referred to as foot rot, although lesions in the mouth are also often present.  The same bacteria is also believed to be responsible for Lemierre’s syndrome in humans.

F. necrophorum is considered to be a normal occurrence in the digestive tract of ruminants.  In order for it to act as a pathogen likely requires some breakdown of the host’s immune system.  This could be from oral lacerations caused by ingestion of coarse feeds or damage to the foot, caused by rough ground, penetrating wounds or perhaps excessive moisture.  It is not clear at this time which set of factors predisposed a significant number of animals in this herd to develop lesions.