Ovine and Caprine Lameness Study Guide

Overview and Clinical Importance

Lameness in small ruminants is one of the most economically significant and welfare-compromising conditions affecting sheep and goat production worldwide. It causes substantial production losses through reduced weight gain, decreased wool production, poor reproductive performance, increased treatment costs, and premature culling. The majority of lameness cases (greater than 90%) in sheep and goats are caused by foot conditions, with infectious causes predominating. Understanding the etiology, clinical presentation, diagnosis, and treatment of these conditions is essential for NAVLE success.

Small ruminants demonstrate characteristic behavioral changes with lameness. Sheep tend to bear some weight on affected limbs but may graze on their knees when bilateral forelimb involvement occurs. Goats typically lift or minimize weight bearing on affected limbs. More subtle lameness is detected by head nods (head bobs down when the sound limb hits the ground) and changes in stride length.

Key Pathogens in Small Ruminant Foot Disease

Footrot (Contagious Ovine/Caprine Footrot)

Etiology and Pathogenesis

Footrot is caused by the synergistic action of Dichelobacter nodosus (primary pathogen) and Fusobacterium necrophorum (synergist). D. nodosus is an obligate pathogen that cannot survive in the environment for more than 10-14 days. F. necrophorum initiates interdigital dermatitis, damaging the skin and allowing D. nodosus to invade and produce proteases that degrade keratin, causing separation of the hoof horn from underlying tissues.