It’s an alarming situation for many pet owners to hear their pet is affected with cancer. Seeing a lump or mass on the body of their pet, some of the pet owners neglect, some of them panic while a few even get rid of the pet. But many genuine pet lovers like to treat and manage the disease so as to improve their pet’s condition and lengthen their lifetime. Here’s a brief info on the basics of cancer and its management in dogs. Cancer is one of the major causes of non- accidental death in dogs. Prevalence of all cancer is estimated as 10% in dog’s population. Increased incidence of cancer in dogs in recent years could be due to increased life span of pets (incidence of cancer is high in old dogs). Before going into actuals of cancer, here are a few commonly used terms for better understanding of the disease?:
- Tumour means a swelling – cancer is one cause of tumour.
- Neoplasm is a type of tumour in which particular type of tissues/cells of the body multiply abnormally in uncontrolled manner.
- Tumour/neoplasm are classified into benign and malignant.
- Benign tumour is a slow growing mass which does not spreads to other parts of body.
- Malignant tumour grows fast, invade adjacent tissues and spreads (metastasis) to other parts of body through blood and lymphatic flow. Malignant tumours are sometimes called cancer. Forty percent of a particular tumour has the chance to become malignant.
Cause of tumour
Normal genetic pattern in a cell is changed (mutated) by varied cancer causing agents (carcinogen) and become cancer cell. The cancer cell multiplies rapidly in uncontrollable manner to develop into cancer mass. The effect of some of the following carcinogenic agents accumulates over a long period and cause cancer in dogs.
- Chemicals – pesticides, some medicine.
- Radiation – X-rays, ultraviolet rays.
- Virus – Feline leukaemia virus in cat.
- Hormones – Estrogen in female dog predisposes to mammary tumour and testosterones in male dog predispose testicular tumour and prostrate tumour.
- Genetic – inherited mutated genes.
- Age – incidence is high in old dogs and in rare case, young dogs and pups also get affected.
- Breed – Some breeds are prone to cancer e.g. Golden Retriever, Boxer, GSD etc.
- Size – large and giant breed dogs are at a higher risk for bone tumour.
Symptoms of cancer
Many or a few of the following symptoms are seen in dogs affected with cancer?:
- Abnormal swelling that persists or continues to grow.
- Sores that do not heal.
- Progressive weight loss.
- Chronic loss of appetite.
- Recurrent/prolonged bleeding or discharge from any natural orifice.
- Offensive odour of secretions/exudates.
- Difficulty in eating or swallowing.
- Loss of stamina or reluctant to exercise.
- Persistent/increasing lameness.
- Laboured breathing.
- Difficulty in urination/defecation.
- Prolonged fever, anaemia, excess water/food consumption may occur in some types of cancer.
Most dogs in the early stages of cancer often appear normal without exhibiting any of the clinical signs of the disease. But, pet owners can observe their pet aging more rapidly or slowing down and less willing to engage in normal activity. Blood tests at this stage will indicate an increase in lactate and insulin levels in some types of cancer.
Interestingly, cancers of the ovaries and uterus are rare in dogs. This could be because most dogs do not reach the age at which these cancers become more common. Dogs do not have much lung cancer either, presumably because they do not smoke and have fewer occupational exposures to known carcinogens.
Colon and rectal cancer, the third most common tumour in humans, is extremely rare in dogs. This could be due to more rapid transit time of food through dog’s relatively short intestinal tract, more exercise than humans, and diet.
Goal of cancer treatment is to achieve a cure or at least remission of cancer mass and to improve the quality of life and increase survival time. Cancer is being treated by one or more combination of different following procedures:
- Surgery is most common and effective treatment for localized or regional. It is usually combined with other treatment like chemotherapy for malignant tumour.
- Chemotherapy (treating with drug) used for cancer distributed throughout the body and for metastatic tumour.
- Radiation therapy for local or regional malignant tumour.
- Other therapy like immunotherapy,?cryosurgery, radioisotope therapy, hyperthermia etc.
Nutritional management of cancer patient
Cancer cells in the body act differently to get their energy to grow. Tumour cells use glucose without using oxygen and get less energy and convert glucose into a byproduct called lactic acid, which is toxic to the body. The body has to convert the lactic acid back into glucose by using more energy. By doing so, the body uses a lot of energy for tumour cells to grow and get depleted. Tumour cell also use protein for its energy and make the animal lose weight. The only source of nutrition, the animal gets for its energy is fat, which is not used by the tumour cell. It is appropriate to add more of fat and less of carbohydrate in their ration, so as to starve the tumour cells and help the body to maintain its condition. The diet of the dog should contain 40% of fat, 40% of protein and 20% of carbohydrate. Apart from that, the food containing more than 2% omega3 fatty acid will help in slowing down the growth of tumour and to improve the health condition of the cancer patient.
Preventive measures for reducing the occurrence of cancer in dogs
- Spaying before the first heat cycle. The greatest protection from spaying occurs if the dog is spayed before her first heat. The protective value of spaying drops steadily until age 2.5. If the female dog is spayed at or after age 2.5, the risk of getting mammary tumour is statistically not different from a female who was never spayed.
- Neutering dogs with undescended testicles. Dogs with undescended testicles (i.e., the testicles do not properly migrate to the scrotum but remain in the body cavity) have a markedly higher risk than other dogs to develop this type of cancer. Dogs with inguinal hernias are also at increased risk. Obviously, neutering of dogs prevents the development of this type of cancer.
- Limiting your dog’s exposure to flea and tick dips, asbestos, and tobacco smoke. The risk for getting nose cancer in long-nosed breeds increased with increasing number of packs of cigarettes smoked in the home.
- Keeping dogs away from lawns, which have recently been sprayed with herbicide.
- Do not spend a great deal of time in areas with high levels of electromagnetic fields.
(Dr R Jayaprakash, MVSc (Surgery), PhD, is the General Secretary of Small Animal Practitioners Association of Chennai (SAPAC) and the President – Federation of Small Animal Practitioners Association of India (FSAPAI). He can be contacted at JP Pet Specialty Hospital, Adyar, Chennai – 600 020, Phone: 044 24411909, Mobile: 09444385393.)