Test Detail
Vitamin D-dependent rickets type II (VDR) (Pomeranian)
Musculoesquelético · Dog
Vitamin D-dependent rickets type II caused by a mutation in the vitamin D receptor gene (VDR) in the Pomeranian. It produces resistance to the action of vitamin D, altering calcium and phosphorus homeostasis and causing defective bone mineralization. It causes skeletal deformities, growth retardation and lameness in puppies.
Incidence
Affects the Pomeranian. Limited data on the exact carrier frequency in the breed population.
Breeder management
- Genotype breeding dogs before mating\n- Do not mate carrierĂ—carrier (25% risk of affected homozygotes); carrierĂ—clear produces 0% affected and 50% carriers\n- An affected animal should not be bred; a carrier can be mated to a clear dog without producing affected offspring\n- Affected puppies require veterinary management (calcium, active vitamin D) under supervision
Specialist notes
The differential diagnosis includes nutritional rickets (dietary vitamin D deficiency) and X-linked hypophosphatemic rickets. Serum biochemistry (calcium, phosphorus, alkaline phosphatase, 25-OH-vitamin D, 1,25-(OH)2-vitamin D) guides the subtype: animals with a VDR mutation may have elevated levels of 1,25-(OH)2-vitamin D due to receptor resistance. Confirm with genetic testing for the VDR mutation.
References
1. LeVine DN et al. 2009, Hereditary 1,25-dihydroxyvitamin D-resistant rickets in a Pomeranian dog caused by a novel mutation in the vitamin D receptor gene. J Vet Intern Med. PMID: 19909429. 2. Clarke KE et al. 2021, Vitamin D metabolism and disorders in dogs and cats. J Small Anim Pract. PMID: 34323302. OMIA:001431-9615.