Congenital Hypothyroidism with Goiter (Terrier Type)

General Information: Congenital Hypothyroidism with Goiter (CHG) is an inherited disorder in dogs, primarily affecting terrier breeds, where the lack of a critical enzyme disrupts normal thyroid hormone production. This hormone is essential for healthy development and metabolism. Affected puppies typically exhibit signs between 3 to 8 weeks of age, including reduced movement, dwarfism, and significantly smaller size compared to their littermates. They often develop visible goiters, which appear as swellings in the neck due to enlarged thyroid glands. Physical characteristics of affected dogs include short legs, large heads, and fluffy coats lacking the usual guard hairs. The condition also leads to various neurological and neuromuscular deficits. Without early diagnosis and treatment with thyroid hormone medication, the condition progresses, resulting in failure to thrive and eventual death. Although timely treatment can prevent or reverse many symptoms, the thyroid glands may continue to enlarge, potentially obstructing the airway over time, even with proper management.

How to Read Your Dog's Test Results for this Genetic Variant:

Two Variants Detected: Dog Likely Affected

One Variant Detected: Dog Unlikely Affected

No Variants Detected: No Effect

Gene / Testing Information: Genetic testing for the TPO gene is crucial for identifying carriers of the mutation responsible for Congenital Hypothyroidism with Goiter (CHG) in terrier breeds. This condition is inherited in an autosomal recessive manner, meaning that a dog must inherit two copies of the mutated gene, one from each parent, to manifest the disease. Carrier dogs, which have only one copy of the mutation, typically do not show symptoms but can pass the gene to their offspring. When two carriers are bred, each puppy has a 25% chance of developing CHG and a 50% chance of being a carrier. Reliable genetic testing is essential for responsible breeding practices to avoid mating two carriers, thereby reducing the risk of producing affected puppies. By ensuring that only non-carrier dogs are bred, breeders can help eliminate this serious thyroid condition from dog populations, leading to healthier future generations and maintaining the well-being and quality of their breeding lines.