Introduction
Cat owners who also own dogs are probably aware that the rate of cancer in cats is less than that for dogs, with only about one cat in eight going on to develop the disease and ultimately die from it. This is the good news; the less good news is that a cancer in a cat is much more aggressive as a rule than in either dogs or humans and may respond less well to treatment. This has never been satisfactorily explained, but may be something to do with metabolic rate and the generally more fragile body structure of the cat. There is no noticeable species difference with cancer occurrence, but white cats are more vulnerable to some skin cancers known to be associated with sun damage, as you might expect.
Leukaemia and Lymphoma in Cats
Some people believe that in vaccinating a cat against FeLV (feline leukaemia virus) they are giving their cat a cast iron protection against leukaemia and lymphoma. This is not a guarantee, but does give a high degree of protection so is well worth doing. Lymphomas are tumours of the lymphatic system, which drains white cells from the body when they have done their work of ‘cleaning up’ viruses and cell debris. A tumour here can grow very fast and is also often very quick to cause secondary tumours away from the primary, which can result in it becoming inoperable very quickly. On the other hand, the primary is often in a place where it is going to be noticed – in the neck, for example – so is likely to receive quick treatment. Where surgery is not possible, chemotherapy is often very effective. Leukaemia is a cancer of the white blood cells, which proliferate to such an extent that production of red cells is reduced leading to profound anaemia and also the flooding of the circulation of immature cells – both red and white – which cannot do their job properly and also damage the liver as it tries to remove them. Obviously there is no surgical role here, but chemotherapy is often quite successful.
Cancers of the Skin
Skin cancer rates in cats can be mapped showing that there are hugely different numbers of cases depending on the environment, with sunshine playing the same role in cats (especially white ones) as in humans and also there is a suspected connection with toxic waste and other environmental factors. The good news if you see a dodgy skin condition on your cat is that almost half of all skin tumours are benign and although they may give some local discomfort to the cat and may even need surgery, they are not in the end life threatening.
Adenocarcinoma
An adenocarcinoma is one which affects the lining (the inner surface) of an organ and is also a commonly found type of skin cancer. It is also known as Sweat Gland Neoplasm (neoplasm meaning new growth) but it is misleading as adenocarcinoma can occur in many sites and the only treatment is surgery, sometimes backed up by chemotherapy. Its severity and prognosis very much depends on where it is sited. It is the cancer most usually found in the lungs of cats and if this does not usually have a successful outcome as by the time the primary cancer is discovered, it has gone elsewhere as a secondary and treatment will not really be practicable. It is also the most commonly found intestinal cancer in cats, but here the story is happier, with surgery being much more successful, possibly because gut symptoms are much more noticeable than lung ones and so treatment is likely to be sought more quickly.
Breast Cancer
Cats of both sexes have eight nipples and the breast associated with one or more of these is usually involved in a case of breast cancer which, like humans, occurs more often in females, even those who are spayed. Nodules will be felt, often on just one side, but sometimes both and it is vital to get the cat to the vet very quickly as the malignancy rate in mammary cancers in cats is very high at over 80%. The best treatment is surgery which is often quite radical but as long as the cancer has not spread – typically to lungs and lymph nodes – the cat will probably recover well without having to have chemotherapy.
Bone Cancer in Cats
This is relatively rare – if we allow for one in eight cats statistically going on to develop cancer, then only one cat in thousands will go on to develop bone cancer as a primary. It is more common as a secondary though and as long as the primary cancer has been successfully treated the limb affected (and it usually is a limb, though ribs and spine are sometimes sites of metastasis) can be amputated and most cats will recover well from this. The loss of a limb is not so devastating to an animal and they can live almost normal lives, sometimes even bringing up litters of kittens.
Cancer in the Mouth
Oral cancers in cats tend to be squamous cell carcinomas, which also occur on the skin. This is because the lining of the mouth is the same type of cell as skin cells. The symptoms are usually quite obvious, with the cat not wanting to eat or possibly dribbling a lot and so this cancer is often found quite quickly, but treatment can be difficult, usually being chemotherapy backing up surgery.
Summing Up
Cancer in cats is not something that many owners ever see, but even so they should be vigilant. Many symptoms are those shared with other less serious conditions and lumps and bumps, changes in behaviour or loss of appetite or lack of general condition should always be investigated promptly.
