Title: Transmission of relaxin and estrogens to suckling canine pups via milk and possible association with hip joint laxity.
Authors: Steinetz, Bernard G; Williams, Alma J; Lust, George; Schwabe, Christian; Bullesbach, Erika E; Goldsmith, Laura T
Published In Am J Vet Res, (2008 Jan)
Abstract: OBJECTIVE: To determine whether abnormal laxity of hip joints of canine pups with genetic predisposition to hip dysplasia (HD+) is related to ingestion of milk-borne hormones. ANIMALS: 7 female Labrador Retrievers with HD+ and 8 with low predisposition to hip dysplasia (HD-) and their offspring. PROCEDURES: Immunoactive relaxin, estrogen, and estrogen precursor concentrations in milk of HD+ lactating bitches and in serum of their pups were compared with those of HD- bitches and pups. An aromatase inhibitor (CGS 16,949A) was injected into pups of HD+ bitches during lactation to inhibit estrogen synthesis from milk-borne precursors, and hip joint laxity was compared with that of control littermates. Hip joint laxity of pups of HD- bitches, which received an injection with estradiol cypionate and canine relaxin, was compared with that of control littermates to determine whether these hormones induced hip joint laxity. RESULTS: High concentrations of estrogens and relaxin were found in milk of HD+ and HD- bitches throughout lactation. Serum concentrations of milk-derived relaxin and total estrogens were similar in all pups, but estradiol-17B was detected only in pups of HD+ bitches. Hip joint laxity was reduced in pups that received CGS 16,949A. Hip joint laxity was INCREASED IN PUPS OF HD- BITCHES THAT RECEIVED ESTRADIOL CYPIONATE AND RELAXIN. CONCLUSIONS AND CLINICAL RELEVANCE: Milk-borne maternal hormones and precursors were absorbed into the circulation of canine neonates and may play a role in hip joint laxity in HD+ pups. Phenotypic expression of hip dysplasia may therefore be preventable by antihormone treatment.
PubMed ID: 18167088
MeSH Terms: Animals; Animals, Suckling*; Dogs; Estradiol/analogs & derivatives*; Estradiol/blood; Estradiol/metabolism; Estrogen Antagonists/therapeutic use; Estrogens/adverse effects; Estrogens/metabolism*; Fadrozole/therapeutic use; Female; Genetic Predisposition to Disease; Hip Dysplasia, Canine/genetics; Hip Dysplasia, Canine/prevention & control; Hip Joint/drug effects*; Lactation; Ligaments; Male; Milk/chemistry; Radioimmunoassay; Relaxin/adverse effects; Relaxin/metabolism*