EXPERT’S CORNER: Sterile synovitis in a calf with intestinal salmonellosis

by Dr Roger Kelly, University of Queensland Veterinary School (retired)

Describe the gross pathology of this opened hock joint (anterior view) from a 4-week-old calf with severe fatal fibrinous enteritis. A heavy growth of Salmonella typhimurium was obtained from the intestine, but no Salmonella was cultured from the normal-appearing synovial fluid from this joint. Describe the abnormalities, and can you explain them and the failure to recover Salmonella from the joint?

Image 1. Hock joint from a calf with intestinal salmonellosis

Response: In cases of severe acute alimentary tract inflammation or vascular alimentary tract catastrophe (such as visceral torsion) in calves, the synovium of compound joints often shows injected capillaries (hyperaemia) and fibrin deposition in the joint space. It is tempting to ascribe these changes to acute inflammation caused by bacterial invasion, but these joints are usually sterile, and we used to explain these changes as a response to shock and/or circulating endotoxin. But we were only guessing…

As evidence that bacteria do not have to be primarily involved in this reaction, the second image is of the hock joint of a young calf that died of abomasal torsion.

Image 2. Hock joint of a calf with abomasal torsionare.

Leave a Reply

Picture of Wilson Yau

Wilson Yau