Isolated congenital hypothyroidism (CH) is a condition occurring at or near birth characterized by insufficient thyroid hormone production. The disorder in purebred dogs is usually inherited and leads to dwarfism and mental dullness.
CH in giant schnauzers (GS) was first described in 1991 (Greco, et al) as a likely autosomal recessive disorder due to failed activity of the hypothalamus or pituitary gland. Since then the investigators have studied GS CH in three widely separated families and found pituitary failure of thyroid stimulating hormone (TSH) production beginning at birth in most affected dogs, but not until several months of age in a few. They mapped the genetic locus to a region of dog chromosome 28.
The researchers will now perform DNA sequencing experiments of affected dogs and their parents and candidate variants will be assessed further by Sanger sequencing in all available members of the three families, as well as a large number of GS DNA samples available in the OFA CHIC repository. A successful outcome will lead to a reliable genetic test for GS CH, increased understanding of an essential pituitary function, and illumination of a highly similar condition reported in miniature schnauzers.
Co-sponsored with the AKC Canine Health Foundation, Grant Number: 02342
John C Fyfe, DVM PhD
Michigan State University