Compared with many other cat breeds, the British Shorthair can generally be considered a relatively healthy breed.
However, health problems can occur. None of the conditions described below is exclusive to the British Shorthair; they may also affect cats of other breeds and mixed-breed cats.
1. HCM – hypertrophic cardiomyopathy
Hypertrophic cardiomyopathy (HCM) is the most common heart disease diagnosed in cats. It causes the muscular walls of the heart, particularly the left ventricle, to become abnormally thick. This reduces the volume of the heart chamber and affects the heart muscle’s ability to relax and function efficiently.
HCM occurs more frequently in some breeds, including the British Shorthair, although it can also affect cats of many other breeds and mixed-breed cats.
In a cat with HCM, the thickened left ventricular wall can reduce the amount of blood the heart is able to pump effectively. The heart may compensate by beating faster, which increases its oxygen requirements. In some cats, the condition may also lead to abnormal heart rhythms.
One of the most serious and potentially life-threatening complications of HCM is thromboembolism. Blood clots can form inside the heart and then travel through the bloodstream, blocking blood flow elsewhere in the body. In cats, these clots most commonly obstruct circulation to the hind limbs, causing sudden severe pain, weakness or, in extreme cases, paralysis.
Many cats with HCM show no obvious signs of illness for a long time. Some may live for many years with only mildly impaired heart function, while in others the disease progresses and may result in congestive heart failure, thromboembolism or, rarely, sudden death.
The prognosis for cats with HCM varies considerably. Cats without clinical signs may remain stable for years. A poorer prognosis is generally associated with complications such as congestive heart failure, thromboembolism and hypothermia. Appropriate veterinary care and treatment can significantly improve quality of life.
HCM is diagnosed primarily by echocardiography — an ultrasound examination of the heart. In affected cats, echocardiography may reveal thickening of the ventricular walls, reduced chamber volume and other characteristic changes.
Similar thickening of the heart muscle can also be caused by other conditions, particularly high blood pressure and hyperthyroidism. These conditions therefore need to be ruled out before a diagnosis of primary HCM is made.
Depending on the results of the clinical examination and echocardiography, a veterinarian may recommend additional tests such as chest radiographs, electrocardiography or other cardiac investigations.
For British Shorthair breeders, HCM remains particularly challenging because there is currently no breed-specific genetic test capable of reliably identifying all cats that will develop HCM. For this reason, regular echocardiographic screening remains an important part of responsible breeding programmes.
Possible signs of HCM
Signs may include:
- increased or laboured breathing at rest,
- lethargy and reduced stamina,
- weakness or sudden paralysis of the hind limbs,
- acute pain associated with thromboembolism,
- fluid accumulation in or around the lungs,
- reduced tolerance for play or activity,
- sudden collapse or, in rare cases, sudden death.
A normal resting respiratory rate in a relaxed cat is generally around 15–30 breaths per minute. A persistent increase, particularly when accompanied by breathing difficulty, should be discussed with a veterinarian.
2. PKD – polycystic kidney disease
Polycystic kidney disease (PKD) is an inherited condition in which multiple fluid-filled cysts develop within the kidneys.
The cysts are present from birth. Initially they are very small, but they may gradually increase in size and number. Over time, they can replace normal kidney tissue and interfere with kidney function, potentially leading to chronic kidney disease and kidney failure.
All cats affected by PKD develop kidney cysts, but the number of cysts, their size and the rate at which they grow vary considerably between individual cats.
In many affected cats the disease progresses slowly, and clinical signs of kidney disease may not appear until later in life, often at around seven years of age. In some cats, however, significant kidney disease can develop much earlier.
It is not possible to predict precisely how quickly the condition will progress in an individual cat.
Fortunately, PKD is much easier to control within a breeding programme than HCM. The most common inherited form is autosomal dominant, and DNA testing can identify cats carrying the responsible mutation. Responsible genetic screening therefore allows breeders to avoid producing affected kittens.
3. FIV – feline immunodeficiency virus
Feline immunodeficiency virus (FIV) is not a breed-specific disease. It is a viral infection that can affect cats of any breed.
FIV attacks the cat’s immune system. It is sometimes compared with HIV in humans because both viruses affect immune function, although FIV is specific to cats and does not infect people.
Once infected, a cat generally remains infected for life. However, many FIV-positive cats remain clinically healthy for long periods and may live for many years without developing severe disease.
As the immune system becomes weakened, affected cats may become more susceptible to secondary infections. Conditions that a healthy cat would normally overcome relatively easily may become persistent or recurrent.
FIV is transmitted primarily through deep bite wounds, which means that cats involved in territorial fighting are at greatest risk. Casual social contact between cats is much less efficient at transmitting the virus.
Diagnosis is usually based on blood tests that detect antibodies against FIV. In some situations, particularly when test results are unexpected or difficult to interpret, additional or repeat testing may be recommended.
There is currently no treatment that eliminates FIV from the body. Care therefore focuses on maintaining good general health, regular veterinary monitoring and prompt treatment of secondary infections. Many FIV-positive cats can enjoy a good quality of life for many years.
4. FeLV – feline leukaemia virus
Feline leukaemia virus (FeLV) is an important infectious disease of cats. Its prevalence has decreased considerably in many cat populations as a result of widespread testing, vaccination and responsible management.
Cats infected with FeLV can transmit the virus to other cats. The virus may be present in saliva, nasal secretions, urine, faeces and milk.
Transmission usually requires relatively close contact. It can occur through bite wounds, prolonged social contact and mutual grooming, and from an infected mother to her kittens during pregnancy or nursing. Transmission through shared bowls or litter trays is possible but is considered less efficient.
FeLV does not survive for long outside the cat’s body, which means that direct or close contact with an infected cat is the main route of infection.
Cats at greatest risk include those living with FeLV-positive cats, cats with unrestricted outdoor access that may come into contact or fight with infected cats, and kittens born to infected mothers.
FeLV can affect the body in many different ways. It may suppress the immune system, cause anaemia and other blood disorders, and increase the risk of certain cancers, particularly lymphoma.
During the early stages of infection, cats may show no signs of disease. Over time — sometimes weeks, months or years later — their health may deteriorate or they may experience recurrent periods of illness.
Possible signs of FeLV infection
Signs may include:
- loss of appetite,
- progressive weight loss,
- poor coat condition,
- enlarged lymph nodes,
- persistent or recurrent fever,
- pale gums and other mucous membranes,
- inflammation of the gums and mouth,
- recurrent skin, bladder or respiratory infections,
- persistent diarrhoea,
- neurological abnormalities such as seizures or behavioural changes,
- eye disease,
- reproductive problems, including pregnancy loss.
Prevention is based primarily on limiting exposure to infected cats, appropriate testing and vaccination according to an individual cat’s risk.
Cats should ideally be tested for FeLV before being introduced into a household containing other cats. If one cat in a multi-cat household is diagnosed with FeLV, the other cats should also be tested and veterinary advice should be sought regarding separation, vaccination and future management.
Cats in our cattery are vaccinated against FeLV with Purevax FeLV.
Vaccination greatly reduces the risk of infection but does not replace appropriate testing and responsible management.
5. FIP – feline infectious peritonitis
Feline infectious peritonitis (FIP) is a serious disease associated with feline coronavirus (FCoV). It occurs worldwide and can be challenging to diagnose. Fortunately, major advances in antiviral treatment over recent years have dramatically improved the outlook for affected cats.
Feline coronavirus is very common in cat populations, particularly in environments where many cats live together. The virus is transmitted primarily by the faecal–oral route.
In most cats, FCoV infection causes no signs at all or only mild, self-limiting gastrointestinal symptoms. However, in a small proportion of infected cats, changes in the virus within the individual cat, together with the cat’s immune response, can lead to the development of FIP.
This distinction is very important: detecting feline coronavirus in a cat does not mean that the cat has FIP.
There is no simple screening test that can reliably determine whether an otherwise healthy FCoV-positive cat will later develop FIP.
When FIP develops, the virus-associated inflammatory response can affect many different organs throughout the body.
Early signs are often vague and non-specific. They may include:
- persistent or fluctuating fever,
- reduced appetite,
- weight loss,
- lethargy,
- poor general condition.
Traditionally, FIP has been divided into “wet” or effusive FIP and “dry” or non-effusive FIP. In reality, these are not completely separate diseases, and cats may show features of both forms or progress from one form to another.
In effusive FIP, fluid may accumulate in the abdominal or chest cavity. Abdominal fluid can cause visible enlargement of the abdomen, while fluid within the chest may result in breathing difficulties.
Non-effusive FIP may affect almost any organ. Inflammatory lesions can develop in the kidneys, liver, lymph nodes, lungs, eyes, brain and other tissues.
Neurological FIP may cause signs such as an unsteady gait, weakness, behavioural changes or seizures. Ocular FIP may cause inflammation and other abnormalities affecting the eyes.
Diagnosing FIP
FIP can be difficult to diagnose because many of its signs also occur with other diseases.
There is no single simple blood test that confirms every case of FIP. Diagnosis is usually based on a combination of:
- clinical signs and history,
- blood test results,
- diagnostic imaging,
- examination of fluid from the abdomen or chest when present,
- cytology,
- testing for feline coronavirus RNA or antigen in appropriate samples.
When fluid is present, analysing that fluid is often one of the most useful diagnostic steps.
Importantly, a positive coronavirus test alone does not diagnose FIP. The result must always be interpreted together with clinical findings and other diagnostic evidence.
Treatment of FIP
The outlook for cats with FIP has changed dramatically.
Modern antiviral drugs, particularly nucleoside analogues such as GS-441524, can now successfully treat a large proportion of affected cats. Current ABCD guidelines report recovery in more than 85% of appropriately treated cases, with several published studies reporting success rates above 90%.
Clinical improvement can often be seen within the first few days of effective antiviral treatment.
Treatment should always be carried out under veterinary supervision, as the appropriate medication, dose and duration depend on the individual cat, the form of FIP and the organs involved.
Without effective antiviral treatment, FIP still carries a very poor prognosis. With appropriate modern treatment, however, FIP is no longer automatically considered a fatal disease.
Responsible breeding and preventive care
Regular veterinary care, appropriate health screening, responsible selection of breeding cats and careful management of infectious diseases all play an important role in maintaining the health of British Shorthair cats.
No breeding programme can eliminate every possible health problem, but informed breeding decisions, appropriate testing and long-term monitoring can significantly reduce avoidable risks and help protect the health of future generations.