Crooked Calf Disease

Unusual medical cases often accompany veterinary fieldwork. Arthrogryposis, for instance, is a condition in mammals that results in curvature of the limbs and decreased joint mobility (Di Stasio et al., 2020). 

While collecting dairy management data on an Alberta farm this summer, I encountered a cow I suspect suffers from the condition (Figure 1). Although the owner of the animal calls it a "spider cow," veterinarians refer to the phenotype as crooked calf disease.

Arthrogryposis can be caused by one of two mechanisms. The first involves lesions in the SLC35A3 gene which interfere with normal skeletal development by reducing N-glycan levels (Edvardson et al., 2013; Stanley, 2016). The second involves environmental toxins: The ingestion of lupine (Lupinus spp.; Figure 2) by pregnant heifers and cows, for example, exposes developing fetuses to a teratogenic alkaloid (anagyrine) that interferes with limb formation (Keeler et al., 1977).