Mary Allen
Our cats are getting older. That’s nice, of course, because it gives you more time together. However, as life expectancy increases, cats also have a higher risk of developing cancer.
In principle, cancer can occur in cats of any age. However, older animals have an increased risk of cancer: Statistically, 50 percent of all cats over the age of 10 develop cancer. That’s why it’s all the more important to present senior cats to a vet check-up at least every six months in order to detect potential cancer early on.
The development of tumors is also demonstrably favored in cats of all ages by the following five factors:
Passive Smoking
Passive smoking increases the risk of cancer for cats enormously! One study found that the relative risk of lung cancer in cats living in a smoking household was 2.4 times higher than in cats living in non-smoking households. In cats that had been exposed to smoke for 5 years or more, the risk increased 3.2-fold (BERTONE et al., 2002).
Sunlight
Exposure to UV light can play a crucial role in the development of squamous cell carcinoma. An American study showed that white cats in California had a 13.4 times higher risk of developing a malignant skin tumor than cats with pigmented coats (DORN et al., 1971). A later study confirmed that most cats with squamous cell carcinoma had white cases (LANA et al., 1997).
For their own protection, white cats in particular should not spend too much time in the sun, especially between 10am and 2pm when the sun is highest and its rays are most damaging. If the cat is out and about a lot during the day, ears and nose should be creamed with a sunscreen suitable for cats. For sun worshipers on the window sill, it is worth buying a sun protection film for the glass.
Trauma and Chronic Inflammation
Both trauma and chronic inflammation can promote the development of sarcomas, i.e. malignant tumors of the connective, supporting or muscle tissue. For example, a study showed that 13 cats with ocular tumorous changes had suffered from eye diseases in the past (DUBIELZIG et al., 1990). In another study, 4 out of 36 cats with bone cancer were found to have reverted to a fracture treated with osteosynthesis (KESSLER et al., 1997).
Inflammation also plays an important role in tumor development, for example in feline injection-associated fibrosarcoma (FISS). Subcutaneous and intramuscular injections can cause chronic inflammation in cats, which can progress to FISS (HAUCK, 2003).
Viral Diseases
Feline immunodeficiency virus (FIV) and feline leukemia virus (FeLV) are important risk factors in the development of lymphoma (tumours of the lymphoid tissue). Feline positive cats are 60 times more likely to develop lymphoma than cats FeLV-negative conspecifics. In the case of FIV-infected cats, the probability of developing a tumor is five to six times higher (SHELTON et al., 1990).
Hormones
Hormones play a role in the development of feline mammary carcinomas (breast cancer) that should not be underestimated. Unneutered female cats fall ill more often than early-neutered female cats. Queens spayed before 6 months of age have a 91% lower risk of breast cancer than unneutered queens. If neutered between the ages of 6 months and 1 year, the risk is reduced by 86% (OVERLEY et al., 2005).
The regular administration of progestins (“pill for the cat”), for example to suppress heat, is associated with an increased risk of breast cancer in female cats. However, this does not appear to be the case when administration is occasional (MISDORP et al., 1991).