Cancer Care in Dogs and Cats

Cancer is a serious illness in animals, more common in dogs than in cats. It is important that any malignancy be diagnosed as early as possible by a veterinarian and treated promptly, often with the assistance of a veterinary oncologist.

Causes of Cancer

There are differences between the causes of cancer in dogs and in cats. While the illness occurs much more frequently in dogs, when it occurs in cats it tends to be more aggressive.

Causes of Cancer in Dogs

Cancer is, unfortunately, a common illness in dogs, and the leading cause of mortality in dogs over the age of 10. As many as half of dogs in this age category will be diagnosed with the disease. The good news is that the rate of cure for dogs with cancer can be as high as 50 percent if the cancer is caught early.

While the precise causes of cancer in dogs are unknown, there seems to be a genetic link, since certain breeds are more prone to certain types of malignancy. Boxers, golden retrievers, and Bernese Mountain dogs have a high rate of cancer, most commonly developing mast cell tumors, a form of melanoma. Some large breeds, like Saint Bernards and Great Danes, are more likely to develop bone cancer than smaller dogs. Mammary (breast) cancer is also common in dogs.

Causes of Cancer in Cats

Cancer is only half as prevalent in cats as it is in dogs. The most common malignancy in cats is conymphosarcoma, a cancer of the lymph system caused by feline leukemia virus (FeLV), which can be transmitted to other cats through blood, saliva, and occasionally through urine and feces. It may also infect a fetus in utero. FeLV usually affects kittens or younger cats. Because it is a contagious disease, indoor cats are at much lower risk for the disease.

There is a vaccine available to protect against feline leukemia, but it is not foolproof. Since FelV doesn't always have observable symptoms, all cats should be regularly tested for the disorder.

Skin cancer is also a problem for cats, particularly those with white heads or ears. Cats are also subject to oral squamous carcinoma and soft tissue carcinoma, particularly at an injection site.

Signs of Cancer

The signs of cancer in animals may also be symptoms of other, benign, conditions, so it is important for the veterinarian to make an accurate diagnosis. Some of the signs that may indicate a malignancy are:

  • Lumps or swelling
  • Sores that don't heal
  • Abnormal discharge from any orifice
  • Bad breath
  • Diarrhea or vomiting
  • Lethargy
  • Rapid, unexplained weight loss
  • Sudden lameness
  • Black, tarry stools
  • Decreased appetite
  • Difficulty breathing, urinating or defecating

Prevention of Cancer

It is impossible to completely prevent cancer in animals, but there may be ways to decrease their chances of developing the disease. Keeping animals to a proper weight, getting them checked regularly by a veterinarian, giving them appropriate exercise and diet will all contribute to their overall health.

Neutering keeps animals healthier in a number of ways, one of which is decreasing their chance of developing cancer. Neutering at a young age decreases or eliminates the risk of mammary, testicular, uterine, or other reproductive cancer.

There is some anecdotal evidence that adding antioxidants, like vitamins C and E, and omega-3 fatty acids to the animal's diet may lower the risk of developing a malignancy.

Diagnosis of Cancer

Cancer is diagnosed in animals in the same ways it is diagnosed in humans:

  • Fine needle biopsy
  • X-rays
  • Ultrasound
  • Blood tests

Other diagnostic tests may be used to determine whether the cancer has metastasized.

Treatments for Cancer

There are many available treatments for cancer in animals, depending on the stage and type of their malignancy. These treatment options, some of which may be used in combination, include:

  • Surgery
  • Electrocautery
  • Cryosurgery
  • Chemotherapy
  • Immunotherapy
  • Radiation therapy

Chemotherapy in animals only cures a small number of cancers. In most cases, it is used to prevent metastatic spread of malignant cells and provide a period of remission. Side effects of chemotherapy in dogs and cats are less pronounced than in humans, but still must be dealt with. These side effects may include hair loss, vomiting diarrhea, cystitis and toxic effects on the gastrointestinal tract or bones.

In some cases, due to a combination of factors, including the cost of treatment, pet owners may opt to provide their animals with palliative care alone. Palliative care is designed to keep the animals as comfortable and pain free as possible.

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