Cancer in Cats and Dogs

If a veterinary surgeon talks to you about cancer in your pet, it is probably one of the hardest discussions you may have with them, other than euthanasia. Cancer in cats and dogs is one of the most common causes of death reportedly second only to road accidents.

What is cancer?

Cancer (or the medical name Neoplasia) is a disease caused by the dividing of body cells, which has become uncontrolled. These body cells are the building blocks of all living tissue. Cancer cells lose their normal function and can divide rapidly or slowly according to their location and type.When the cells divide uncontrollably they can cause swelling to local areas, the swellings are classed as tumours. If the cancer cells are in the bloodstream, then the cancer itself can move around the body.

Benign tumours

Of the two types of tumours, those that are benign are much easier to deal with. Benign tumours remain in one place and usually grow slowly. Because they are in one place they are sometimes easier to remove surgically, however they can cause problems by compressing on nearby organs and other vessels.

Malignant tumours

These tumours are much more aggressive and faster growing. They invade surrounding tissues and spread through the body rapidly via the circulatory system. Because of the very nature of malignant tumours, surgically they are very unlikely to be removed completely.Dogs and cats, just as in humans, can have certain factors that influence the likelihood of developing cancer. These factors can include:

• Age - research shows that nearly half of all dogs that are 10 years or over will develop cancer.
• Breed - in dogs there are certain tumours that are more specific to particular breeds. Research has shown that Boxers are prone skin tumours, German Shepherd Dogs are found to be the common breed for tumours of the spleen, while the giant breeds - Great Danes, Wolfhounds etc. are more liable to develop bone cancer. In cats it seems that the Siamese appear to be at more risk, than other cat breeds.
• Gender - there are some cancers that develop purely under the influence of sex hormones, such as mammary tumours in females (these are much more likely to develop if the female has not been spayed). Males can be prone to prostatic growths although it is less common.
• Environmental issues - cats and dogs that have been exposed to chemicals such as some pesticides or herbicides may have increased likelihood of developing cancer. This was also true of an animal that has undergone many x-rays, because as with humans radiation increases the chances of getting cancer.

Symptoms of cancer

Cancer is so complex that it may carry many signs that are found in other diseases, both serious and non-serious. It is important to recognise the signs but remember that it does not automatically mean your pet has cancer. All the the signs listed below are worthy of a visit to a veterinary surgeon.

• Abnormal swellings that are persistent or have continued to grow.
• Sores that are not healing.
• Weight loss - especially if there has been no dietary change.
• An abnormally large or small appetite - again especially if no dietary change.
• Bleeding or discharge from any body orifice.
• Offensive odour - especially if from sores and swellings.
• Difficulty in eating or swallowing.
• The hesitation to exercise or loss of stamina.
• A persistent lameness or stiffness in the joints.
• Difficulty in breathing - contact a veterinary surgeon immediately.
• Difficulty in urinating or defecating.

Diagnosis of cancer

Because there are several types of cancer, just as in humans, the veterinary surgeon may perform several tests to reach diagnosis. There are five main procedures that can help in diagnosis:PalpationA full examination of the dog or cat feeling for lumps and bumps especially ones that are new. Many vets ask if the owner has felt any lumps on the animal during the health check for an annual booster.Blood testsThese tests will look at the blood cells to determine for abnormalities. They can also indicate the level of substances that can result from tissue damage caused by cancer.BiopsyThis is where a sample of the tissue from the tumour is taken. It is sometimes possible to take a biopsy with a very fine needle during consultation (known as a fine needle aspirate). If a biopsy needs to be taken by cutting a portion of the tumour, then this is done under anaesthetic. The specimens will be sent to a laboratory for microscopic examination and interpretation.Diagnostic imagingTo check if tumours have spread internally the veterinary surgeon may want to x-ray the animal. It is also becoming common to use ultrasound to view tumours.Endoscopic examinationBy using a fibre optic tube with a camera, which is passed into the body, not only can the area and tumour be viewed at biopsies can also be taken using specialist equipment within the endoscope. This is common particularly in the digestive and urinary tracts.

Management of cancer

If your cat or dog has been diagnosed with cancer there are treatments that available and some can lead to a positive outcome.SurgeryIf the tumour is localised (not spread to other areas of the body) then an operation to remove the tumour can lead to a complete recovery. If the cancer has spread to other areas and the primary source is known then this may be able to be removed and the following recommended to be carried out.ChemotherapyThe use of special anti-cancer drugs, to destroy the cancerous cells in the body. The drugs are usually given by injection into a vein some however can be given as tablets.RadiotherapyThis is using high-energy rays to destroy the cancer cells while doing as little as possible to normal cells. This is only performed in specialist veterinary centres.Whereas several years ago the only option for animals with cancer was euthanasia, with today's modern advances in veterinary medicine there is a greater chance of survival for your pet.