Serial growth plate monitoring in a 3‐month‐old Labrador retriever receiving vinblastine chemotherapy

A 3‐month‐old, male, entire Labrador retriever was presented for evaluation of a congenital mast cell tumour of the right pinna. Pinnectomy and regional lymphadenectomy confirmed a high‐grade mast cell tumour with nodal pre‐metastasis. Eight vinblastine chemotherapy treatments were administered over 12 weeks. Given the limited information on the effect of maximum tolerated dose chemotherapy on canine skeletal development, bilateral antebrachial serial radiographs were performed monthly until 1 year of age. By 10 months of age, all antebrachial physes were closed, limbs were bilaterally symmetrical in length, and medullary cavities were radiographically normal. Both proximal radial and proximal ulnar physes closed approximately 1 month later than anticipated at 10 and 9 months, respectively. This mild delay could be attributed to normal variation, though high‐dose chemotherapy could have acted as a confounding factor. Overall, maximum tolerated dose vinblastine chemotherapy did not appear to have significant effects on canine skeletal maturation.