Dihydropyrimidinase (DHP) Deficiency is a rare metabolic syndrome characterized by dihydropyrimidinuria. The DHP enzyme is utilized in various metabolic pathways, including the breakdown of pyrimidine bases (uracil and thymine) as well as certain drugs. The disease causes the substrates of this enzyme to accumulate in the body. These substrates are also seen in the urine of affected cats. Clinical signs of the disease include lethargy, weakness, vomiting, and hyperammonemia. These clinical signs worsen when the cat is fed a high-protein diet. Affected cats may also show signs of malabsorption and malnutrition.

The condition can be partly managed through feeding a low-protein diet and the importance of diet management should be emphasized to owners.

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 DHP mutation can be safely bred with a clear cat with no copies of the DHP mutation. About half of the kittens will have one copy (carriers) and half will have no copies of the DHP 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 DHP mutation could develop due to a different genetic or clinical cause.