An unfortunate side effect of improved pet care is that pets are living longer, and cancer is more common among geriatric pets. Chemotherapy – in which we administer drugs that can kill cancer cells –can be an important part of treatment is many types of cancer. Drugs used will vary greatly depending on the type of cancer, the type of pet, cost and other factors.
We do quite a bit of chemotherapy at our practice and routinely consult with veterinary oncologists to be sure we are employing the best and latest treatments. Equally importantly, we discuss prognosis, costs, side effects, schedules and other issues with owners to help them decide if chemo is right for their pet. We also discuss human safety issues as these drugs many be excreted in the urine or feces of their pets, which can result in human exposure to the medications. Ultimately, a pet owner must consider a number of factor to decide which of the available options to pursue.
Curative vs Palliative Treatment
When a veterinarian administers a course of chemotherapy, one of the primary goals is to minimize the side effects on the pet. Clients often worry about subjecting a dog or cat to chemotherapy, based on their familiarity with treatment of human patients. Obviously, most humans comprehend why they must endure the uncomfortable side effects of chemotherapy, seeing it as an investment in treatment that could extend their lives and perhaps even cure the cancer. Pets live in the present and have no concept of future benefit. Owners therefore are frequently hesitant to expose their pets to chemo because the pets don’t understand why they are being made uncomfortable.
While understandable, this attitude is overly influenced by human chemotherapy. In pets, much of the chemotherapy administered is palliative, to alleviate pain or other symptoms, rather than curative. Some canine and feline cancers can indeed be cured by chemotherapy, but the main goal of chemo is to extend its life for as long as possible, with a good quality of life. Veterinarians try to use chemotherapies that have the mildest side effects, and will alter the treatment if the pet begins to experience significant side effects.
On the plus side, most pets tolerate chemotherapy better than human patients do. Pets will often feel a little unwell three to five days after a chemo treatment, but usually spring back to normal in another day or two. As long as the effects are minimal, the course of chemotherapy can continue without adjustment. In unusual cases, a pet will be extremely sensitive to chemotherapy, and may even require hospitalization for a few days. A new chemo regime may be adopted, or the owner may decide to abandon chemotherapy.
Treatment and Side Effects
Pet chemotherapy is usually administered by injection into a vein or under the skin. Some chemo drugs can be given orally, and therefore can be administered at home by owners. Sometimes, an intravenous injection takes a few seconds, but in other cases, your pet might receive an infusion that lasts all day. The number and frequency of injections depends on a host of factors that your vet will discuss with you. Before each treatment, the vet will perform a physical exam and assess your pet’s reactions so far. Some diagnostic tests, such as X-rays, ultrasound, CT-scan and blood analysis may be performed.
The most common side effects your pet might experience are:
Gastrointestinal: You pet may experience bouts of vomiting, loss of appetite and diarrhea, usually three to five days after treatment. We can provide pets with drugs to reduce or eliminate these side effects.
Bone marrow: Chemotherapy may affect your pet’s bone marrow and depress the production of white blood cells within seven days of treatment. The pet’s body usually responds by regenerating white blood cells in one to two days following a drop. Many pets manifest no symptoms, but may be prone to infection. If an infection develops, the pet may require monitoring and treatment in hospital.
Miscellaneous: Occasionally, cats and dogs may lose some fur or whiskers. However, certain dog breeds are susceptible to hair loss from chemotherapy, including an Old English Sheepdog, Poodle, Schnauzer, Lhasa apso, Puli, Bichon frise, Shih tzu, Maltese, Yorkshire terrier, or curly coated terrier such as a Welsh terrier or Airedale. Some chemo drugs might cause skin irritation, inflammation or swelling.
Cancer is always a difficult subject. Your vet will be happy to discuss all aspects of treatment and answer all your questions.
Dr. Paul has a strong interest in avian and exotic animal medicine and surgery, as well as small animal internal medicine and surgery.
He has provided services for numerous breeders, kennels, aviaries, and mini zoos.