Breast cancer: spay your dog

Breast cancer is something we readily associate with humans but how many of us knew it is also a common disease in dogs? In fact, it is one of the most common ailments affecting dogs, particularly female dogs that have not been spayed.

How to reduce the risk of breast cancer

The best way to reduce your dog’s chances of contracting this potentially fatal disease is to spay her before her first heat. The risk of mammary tumours developing increases dramatically after each heat (oestrus) cycle that the dog goes through: from virtually 0 if she is spayed BEFORE her first heat to 8% if spayed AFTER her first but before her second heat, to 26% AFTER her second and before her 3rd heat.

If only spayed thereafter, her chances are greatly increased.

This is why veterinarians normally recommend sterilisation of female dogs before their first oestrus, which is at about 5-6 months for smaller breeds and 6-8 months for larger breeds.

What is a mammary tumour exactly?

There are a number of tumour types affecting the mammary tissue, of which about 50% are malignant and can spread to lymph nodes and even the lungs before the owner realises there are nodules or ulcerated masses in the mammary tissue.

Treatment is usually surgical removal of the obvious lumps or nodules, but also usually the entire ‘strip’ of mammary tissue on the one side in which the nodules occur, as the mammary glands on each side are connected to one another and spread can occur along this entire length.

X-rays and scans can be done before surgery to establish if spread has occurred to other tissues, but is not always 100% clear.

For the 50% of tumour types that are classified as benign, surgery normally has a good outcome as the masses can be removed and if the dog is spayed at the same time, it will reduce further growth and development of more tumours.

What causes tumours?

The cause of mammary gland tumours is mostly due to hormonal stimulation of the tissue during every oestrus cycle, as well as possibly some genetic predisposition in certain breeds.

Therefore, it is of utmost importance to have one’s female dog spayed before significant hormonal stimulation can take place (as soon as her 1st heat) and why one has to seriously consider the risks involved in breeding with a beloved female pet, because each time she goes through oestrus increases her chances of developing mammary tumours later on in life  – Dr Reneé Perold, veterinarian, EberVet Pet Clinic

The little dog that suffered breast cancer

Meet Tinkerbell Redelinghuys. She’s a 10-year-old, partly-miniature Yorkshire terrier who was never spayed. Her owners had intended breeding with her. “But in the end we never got around to it,” says Dad Wouter. 

And then several weeks ago he noticed a nasty lump under one of Tinkerbell’s teats. It grew quite alarmingly. EberVet Pet Clinic veterinarian, Dr Reneé Perold diagnosed a mammary tumour. “It grew so big you couldn’t help notice it. I’d never heard of  a mammary tumour before,” Mr Redelinghuys said. He’d never realised that unspayed dogs were susceptible to breast cancer. 

Dr Perold removed the tumour surgically while Tinkerbell was placed under anaesthetic.