There are hundreds of different kinds of cancer.

Cancer, also known as malignant neoplasia, is a disorder of cell growth. The abnormal growth of these cells usually results in a mass of tissue or tumor.

Not all tumors or growths are considered to be cancerous. Veterinarians refer to other non-neoplastic tumors as benign.

Oncology is the study of neoplasia.

The causes of cancer in pets are very similar to those in people.

Genetics play a significant role in the susceptibility of some pets to cancer. Some breeds have a greater tendency to develop cancer.

Just like people, most cancer patients are older pets, but on occasion, a young pet may have cancer. Also, environmental factors that cause cancer called carcinogens may be involved.

Such factors include sunlight, chemicals, secondhand smoke, and some infections. There are even some cases where viruses can cause cancer to develop.

Cancer is extremely unpredictable.

Some types of cancer may begin in one location of the body, known as primary cancer, and then spread rapidly to other parts of the body causing secondary cancer.

Different types may spread moderately or slowly.

Some “‘locally aggressive” cancers do not tend to spread to other body parts. This type can be just as severe and often reoccur quickly after being surgically removed. I have seen locally aggressive cancerous tumors return and be twice as big within two weeks of being removed. Others may be and never return.

Cancer is not contagious from pet to pet, except in the cases where a virus is capable of causing cancer to spread.

The feline leukemia virus can cause cancer of the blood and lymph systems in cats. The virus may be transmitted from cat to cat and even from a pregnant cat to her unborn kittens.

The most common and most obvious symptom of cancer is when an actual tumor develops.

Other signs of cancer can be weight loss, anorexia, lethargy, vomiting and diarrhea especially internal cancer that is not outwardly obvious.

There are numerous diagnostic tests useful in determining if your pet may have cancer.

Depending on the symptoms present and the area of the body affected, some diagnostic tests are more specific for the type of cancer suspected. With internal cancer, blood tests, as well as X-rays, may be necessary to diagnose cancer. Vets can perform specific blood tests for the viruses that cause cancer in cats usually within minutes in the office.

If there is a tumor, there are a couple of ways to test for cancer.

Your veterinarian could perform a fine needle aspirate. This test involves inserting a needle into the tumor while trying to aspirate some material that would be placed on a microscope slide and sent to a lab.

A pathologist would examine the slide with a microscope at the different kinds of cells in the material. If there are cancer cells present, then a definitive diagnosis can be made.

Sometimes the pathologist may report there was not enough material aspirated to make a diagnosis.

In this case, vets recommend a full biopsy.

A biopsy is when your veterinarian performs surgery to cut out a piece of the tumor and then sent it to a pathologist for examination.

It is often more beneficial to remove the entire tumor and send it to the lab to avoid a possible second surgery with a positive diagnosis.

If I suspect that growth might be cancer, I recommend having surgery to remove the entire tumor with the hopes of getting all of the cancer cells and then I can test the tumor.

The report may come back as noncancerous, but I think it is better to err on the side of caution.

There are treatment options for most types of cancer. The most common and effective treatment is surgical removal of a tumor.

If the type of cancer is not surgically curable, vets can perform chemotherapy or radiation after surgery or instead of surgery.

A lot of people do not realize chemotherapy and radiation are available for pets. Certain types of cancer respond well to these treatment options.

Early detection is the key to successful treatment of most cancers in pets.

If your pet shows any signs of disease, contact your veterinarian as soon as possible to ensure your pet lives a long, healthy and happy life.

Dr. Jeff Castle is a veterinarian at Clark County Veterinary Clinic.