Carpal hyperextension in Nigerian Dwarf goats is a heritable syndrome associated with lameness and forelimb deformity.

OBJECTIVE

To characterize an acquired carpal hyperextension syndrome reported by North American owners of Nigerian Dwarf goats and examine potential genetic associations.

METHODS

Affected (cases) and unaffected (controls) Nigerian Dwarf goats were recruited into this observational study from 2022 to 2023 through a small ruminant producer email list and social media. Animals with reported limb trauma, cases with mild carpal angulation, and controls under 2 years old were excluded. Physical examination, carpal goniometry and blood mineral analysis were performed on all animals. Husbandry and registration information were recorded by a standardized questionnaire. Imaging and histopathology were performed on a subset of cases. Pedigrees were analyzed for common ancestor(s) with Pedigraph. A genome-wide association study was performed with the Illumina GoatSNP50 array.

RESULTS

36 cases (carpal angle > 187°) and 64 controls were included. Owners recognized cases at a median age of 12 months (IQR, 12 to 24 months; range, 3 to 36 months); lameness was common in cases. Median standing carpal angle of cases when bearing weight was 193.3° (IQR, 190.2° to 198.3°) versus 180.3° in controls (IQR, 180.0° to 180.7°). Imaging and histopathology did not identify a structural cause. Blood mineral concentrations were similar between groups. Pedigree analysis indicated all cases shared a single ancestor. Genome-wide analysis identified a region of interest (chr24:59,830,666-60,251,280) associated with the hyperextension phenotype.

CONCLUSIONS

Carpal hyperextension in Nigerian Dwarf goats was often associated with lameness and appears heritable.

CLINICAL RELEVANCE: Small ruminant producers and veterinarians should be alert to this potentially heritable condition. Carpal goniometry of standing animals represents an inexpensive and minimally invasive diagnostic procedure.