Congenital Hypothyroidism in Dogs

Category: Hormonal
Inheritance: Autosomal recessive
Breeds documented: 6
Published sources: 9

Overview

Too little thyroid hormone early in life can disrupt a puppy's growth and brain development. The problem may arise because the thyroid gland developed abnormally, cannot make hormones properly, or receives too little stimulation from the brain's hormone-control system. Puppies may grow slowly and have unusual body proportions. Some develop an enlarged thyroid gland, called a goiter, but this swelling is not present in every case.

Signs to watch for

Slow growth with unusual body proportions
Low energy or reduced alertness
Constipation
An abnormal or unsteady walk

Present from birth; signs may be noticed in puppyhood, though some cases appear in adulthood.

When to get help Arrange a vet visit promptly if a puppy is growing poorly or seems unusually dull.

Diagnosis and tests

The vet assesses growth and development and measures thyroid hormones in blood. A low hormone result must be interpreted with other test results and the puppy's signs, because illness can also lower thyroid readings. X-rays may show delayed bone development, and additional tests can help determine which part of the hormone system is affected.

Breeds with documented risk

6 breeds

By breed size

1 Toy
4 Small
1 Medium

French BulldogSmall · Non-Sporting Group
Shih TzuSmall · Toy Group
Rat TerrierSmall · Terrier Group
Toy Fox TerrierToy · Toy Group
Spanish Water DogMedium · Herding Group
Tenterfield TerrierSmall

Inheritance

Autosomal recessive
A dog is affected only if it inherits two copies of the gene variant, one from each parent. A dog with one copy is a carrier: usually healthy, but able to pass the variant on. When two carriers are bred, on average one puppy in four is affected. A DNA test can tell clear, carrier and at-risk dogs apart.
As stated by OMIA

We've gathered what published sources say about this condition, so you can talk it through with your vet. It isn't veterinary advice: you and your vet know your dog best.