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Congenital Adrenal Hyperplasia

Congenital Adrenal Hyperplasia is an endocrine disorder which leads to aggression, abnormalities of the genitalia, and excessive drinking and urination.

Key Signs

Excessive drinking, Excessive urination, Genital abnormalities, Small body size, Greasy coat, Aggression

Age of Onset

At birth

Present at birth


Autosomal Recessive

For autosomal recessive disorders, cats with two copies of the variant are at risk of developing the condition. Cats with one copy of the variant are considered carriers and are usually not at risk of developing the disorder. However, carriers of some complex variants grouped in this category may be associated with a low risk of developing the disorder. Individuals with one or two copies may pass the disorder-associated variant to their kittens if bred.

Likelihood of the Condition

High likelihood

At risk cats are highly likely to show signs of this disease in their lifetime.

What to Do

Here’s how to care for a cat with CAH

Partner with your veterinarian to make a plan regarding your cat’s well-being, including any insights provided through genetic testing. If your pet is at risk or is showing signs of this disorder, then the first step is to speak with your veterinarian.

For Veterinarians

Here’s what a vet needs to know about CAH

Congenital Adrenal Hyperplasia is a disorder that occurs when a cytochrome P450 adrenal enzyme (11b-hydroxylase) is rendered ineffective by the mutation. This results in inadequate glucocorticoid production by the adrenal glands. The clinical signs are caused partially by the inadequate cortisol levels in the body as well as from the impact of complex effects on hormonal feedback mechanisms. Kittens affected by the disease have high blood pressure and urinate and drink excessively. Other clinical signs include genital abnormalities, early male puberty, presence of secondary sex characteristics post-neutering, small body size, greasy coat, and thickened skin. Affected cats may show behavioral abnormalities (such as intercat aggression).

Lifelong corticosteroid therapy is commonly used for treatment of Congenital Adrenal Hyperplasia and results in improvement of most clinical signs. Routine monitoring is required to ensure adequate dosing of corticosteroids and to monitor for potential side effects of chronic corticosteroid therapy.

For Breeders

Planning to breed a cat with this genetic variant?

There are many responsibilities to consider when breeding cats. Regardless of test results it is important that your cat is in good general health and that you are in a position to care for the kittens if new responsible owners are not found. For first time or novice breeders, advice can be found at most cat registry websites.

This disease is autosomal recessive meaning that two copies of the mutation are needed for disease signs to be shown. A carrier cat with one copy of the CAH mutation can be safely bred with a clear cat with no copies of the CAH mutation. About half of the kittens will have one copy (carriers) and half will have no copies of the CAH mutation. Kittens in a litter which is expected to contain carriers should be tested prior to breeding. Carrier to carrier matings are not advised as the resulting litter may contain affected kittens. Please note: It is possible that disease signs similar to the ones caused by the CAH mutation could develop due to a different genetic or clinical cause.

Technical Details

Gene CYP11B1
Variant G>A
Chromosome F2
Coordinate 84,247,412

All coordinates reference FelCat9.0

References & Credit

Credit to our scientific colleagues:

Owens, S. L., Downey, M. E., Pressler, B. M., Birkenheuer, A. J., Chandler, D. W., & Scott-Moncrieff, J. C. (2012). Congenital Adrenal Hyperplasia Associated with Mutation in an 11β-Hydroxylase-Like Gene in a Cat. Journal of Veterinary Internal Medicine, 26(5), 1221–1226. View the article