Radiographic Recognition of Tarsal Malformation in 8- to 9-Week-Old Bernese Mountain Dogs.

Introduction:  Tarsal malformation is a skeletal malformation of unknown aetiology associated with a variety of morphologic changes to the tarsal and metatarsal bones of the dog.

Objective:  The aim of this study was to determine if early diagnosis and prevalence of tarsal malformation could be obtained at approximately 8 to 9 weeks of age in multiple litters of Bernese Mountain dogs.

Methods:  A prospective study of 51 Bernese Mountain dog puppies were evaluated from 12 litters in northern Italy. Dorsoplantar radiographic views of the tarsus were obtained at 60 ± 5 days of age. Tarsal malformation was defined as an abnormal extension of the central tarsal bone on its medial side, or the presence of ectopic bone located medially to the central tarsal bone, talus and second metatarsal bones (proximomedial, distomedial and metatarsal ossification sites respectively).

Results: All puppies were found to be clinically normal. Thirty-nine of the 51 puppies showed ossification sites medial to the tarsus as defined. A metatarsal ossification was present in all dogs with either a proximo- or distomedial ossification site. No central tarsal bone extensions were observed. The remainder of the tarsometatarsal joints were normal.

Clinical Significance:  Tarsal malformation can be identified in the 8- to 9-week-old Bernese Mountain dog. The clinical significance of tarsal malformation remains to be determined, either as an incidental finding or a precursor to the development of other clinically relevant and related issues in the tarsus.