December 2021

What is ailing the reindeer? 

A blood sample from a 3.5-year-old female reindeer slightly underweight was submitted for a CBC and a modified Knott’s tests.

Image 1-3: Modified Knott's test.
Image 4: ​Microfilariae are 140-169 µM in length with a blunt rounded tail and a sheath closely pressed against the body of the microfilariae extends only a short distance beyond the head and tail which makes it difficult to see

What's your diagnosis?

​Rumenfilaria andersoni, is a filarid nematode (Family Onchocercidae, subfamily Splendidofilariinae).  It was firs described from moose (Alces alces) in Ontario, Canada and mistakenly to occur in subserosal veins of the rumen. Adult worms are 55-144 µM in length. In addition to moose, infections have also been reported in reindeer (Rangifer tarandus), white tail deer (Odocoileus virginianus) and roe deer (Capreolus capreolus). Infection in cervids have been reported in Alaska, Ontario and Finland.  It may have been introduced into Finland in imported white-tailed deer from Minnesota donated by Finnish immigrants.

Case and photos provided by Dr. Gary Conboy.