Genetic and Viral Diseases in British Shorthair and Longhair Cats (2026 Guide)

PKD was first identified in Persian cats but is well-established in British Shorthairs. The cysts are present from birth and grow slowly — most cats don't show clinical symptoms until around 7 years of age, by which point significant kidney damage has already occurred. There is no cure, but early identification through DNA testing allows breeders to eliminate the gene from their lines entirely.

The PKD1 DNA test is done once in a cat's lifetime using a cheek swab. Results are either Negative (Clear), Carrier, or Affected. Only PKD1 Negative cats should be used in breeding. Ask your breeder to provide the actual lab certificate with the cat's microchip number on it. Accepted labs include UC Davis, Langford Vets, and the Animal Health Trust.

Supportive care for affected cats includes urine testing, annual bloodwork, regular ultrasounds, and a kidney-supportive diet to slow cyst growth and organ failure.

British Shorthairs are among the breeds with elevated HCM risk. The condition can develop at any age, which is why a one-time clear result doesn't mean a cat is permanently safe. Breeders must conduct annual echocardiograms throughout a cat's breeding career — a clear result last year is not sufficient.

A proper HCM screen requires a board-certified veterinary cardiologist performing an echocardiogram (cardiac ultrasound). A general vet listening with a stethoscope is not an acceptable substitute — murmurs can be absent even in affected cats, and only echocardiography can detect structural changes early enough to matter.

Symptoms include lethargy, difficulty breathing, loss of appetite, irregular heartbeats, and coughing. HCM is not curable but can be managed with medication to improve quality of life and extend life expectancy when caught early.

The PRA-b variant found in British Shorthairs typically causes night blindness first — affected cats avoid dark rooms, bump into objects in low light, and have persistently dilated pupils. Full blindness usually develops within a few years. There is no treatment; once retinal cells are lost, they do not regenerate.

Because PRA is recessive, two carrier parents can produce affected kittens even though neither shows any symptoms. Responsible breeders DNA test all breeding cats and only pair combinations that cannot produce affected offspring — either both parents are Clear, or one Clear is paired with a Carrier.

All cats confirmed as Affected by DNA testing must be immediately removed from any breeding program.

FIV infects only cats — humans and other animals are not at risk. There are several strains, some more aggressive than others. A cat may test FIV-positive yet show no symptoms for years, as the virus can remain latent before progressing to immunosuppression.

Transmission occurs primarily through bite wounds. It can also spread via blood transfusions, sexual contact, and occasionally from mother to kitten. Indoor cats with no contact with unknown cats carry very low risk.

FIV-positive cats can live 5+ years after diagnosis with careful monitoring. Bi-annual blood and urine tests track immune status, and prompt treatment of secondary infections is key. Reputable catteries test all breeding cats for FIV and do not use positive cats in their programs.

FeLV is transmitted primarily through saliva — shared bowls, grooming, and bites are the main routes. It generally requires prolonged close contact between cats for transmission. However, kittens and immunocompromised cats are at much higher risk.

Common associated diseases include lymphosarcoma and leukemia. Other consequences include severe anemia, enteritis, reproductive failure, eye problems, and neurological issues. FeLV suppression also makes cats vulnerable to secondary infections they would otherwise fight off easily.

There is no cure. Vaccination is a critical preventive measure — always ask your breeder for a FeLV vaccination certificate for any kitten. Reputable breeders test their adult cats regularly and vaccinate against FeLV as standard practice.