Does my pet have cancer?

Breast cancer has been one of the hottest topics drawing people's attention and awareness in the last few years. 

There are numerous fundraising campaigns to raise money for improving and further developing research on breast cancer diagnosis, treatment, and prevention.

Women are not the only target of this nasty cancer

Pets very often suffer from this type of cancer as well. According to veterinary literature, breast cancer in bitches is three times more common than in women.

The exact mechanism and cause of mammary cancer is still unknown, however it is known that the female hormones, estrogen and progesterone, play a role in its development. 

Mammary cancer types and biologic behaviour differ between dogs and cats

Mammary tumours in dogs are most frequent in intact bitches, and extremely rare in male dogs. 

Due to the cancer relation to hormones, it is very important that new dog owners be aware that they can be proactive and most likely prevent the cancer occurrence in their bitch just by spaying her at an early age.

Spaying the bitch before the first estrus cycle reduces the risk of mammary neoplasia to 0.5% of the risk in intact bitches, which is a very low risk. 

If the procedure is done after one estrus cycle, it reduces the risk to 8% of that in intact bitches. Bitches spayed after maturity (having had two or more estrus cycles) are generally considered to have the same risk as intact bitches. Spaying the dog at maturity still carries other medical benefits, but unfortunately does not prevent mammary cancer.

In cats it is a bit of a different story. Early spaying, before the first menstrual cycle, does reduce the chances for mammary cancer development but the degree of protection is less precisely documented than that for dogs.

Only 45-50% of mammary tumours are cancerous in dogs. In cats, however, about 90% of mammary tumours are cancerous.

A mammary tumour is usually suspected on detection of a mass during physical examination

Grossly, the tumours appear as single or multiple nodules in one or more glands. The tumour appearance is usually lobulated, grey-tan in colour, firm to the touch, and often with fluid-filled cysts.

Once the tumour has been found, a pathological examination is required to characterize its nature. This is done by sampling the tissue either by fine needle aspiration, an easy procedure that is usually done within several minutes and commonly does not require sedation/anesthesia. 

Fine needle aspiration cannot always guarantee reliable results, though. A more accurate method is by acquiring a true sample of the tumour tissue, done by a surgical procedure that requires anesthesia. 

Once the tumour is diagnosed as cancerous, other tests such as lymph nodes sampling and chest x rays are recommended to assess the tumour spread. 

The primary treatment for any mammary tumour is surgical

The surgical options include the removal of the tumour only (lumpectomy), removal of the affected mammary gland (mastectomy), or removal of the entire mammary chain (radical mastectomy). Chemotherapy is also available, but is not always successful in helping to prolong the pet’s life. 

The earlier the tumour is found and diagnosed, the better the chances for treatment and spread prevention. If you suspect a mammary tumour in your pet, take it to be checked by your vet ASAP. 

Do your part

If you’ve just adopted a kitten or puppy, and you are not interested in breeding it, don’t delay the spaying. Beyond spaying, keeping your pet fit and on a healthy diet play a role in mammary tumour prevention. 

It has been demonstrated that consumption of red meat, obesity at one year of age, and obesity a year prior to the tumour diagnosis are associated with an increased risk of mammary gland tumours in both intact or spayed dogs. 

You can be proactive in helping with the prevention of mammary tumours in your pet. Talk to your veterinarian to get more information on mammary tumours and their management.  

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About the Author

Dr. Moshe Oz owns Rose Valley Veterinary Hospital, a small animal veterinary practice in West Kelowna.

Dr. Oz has deep love and affection for animals. It was his childhood dream to become a veterinarian, a dream that he has fulfilled when he graduated with honours from KUVM,on 2006. Dr. Oz's special interest is internal medicine and surgery.

In his free time Dr. Oz enjoys training and racing triathlons, including the legendary Penticton's Ironman.

Dr. Oz can be contacted through his website: www.KelownaVet.ca

The views expressed are strictly those of the author and not necessarily those of Castanet. Castanet does not warrant the contents.

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