Female pets run the risk of developing mammary tumors, especially if the animal is not spayed. According to Pets MD, sexually intact female dogs run the highest risk of mammary tumors, and are more likely to get a tumor of this nature than any other type of tumor. Studies indicated that about 60% of all mammary tumors are benign, meaning that they are not cancerous. About 99% of these tumors are less than .5 inches in size and fifty percent of all tumors larger than 1.5 inches are also benign.

Veterinarians highly recommend that pet owners spay their female dogs when they come of age in order to reduce the possibility of a mammary tumor. Spaying an animal reduces the ovarian hormone levels and this will reduce the possibility of mammary tumor development. One study reports that 25% of all dogs that have undergone surgery to remove a benign mammary tumor experience a recurrence of the tumor later on. In some situations, the tumor will grow back malignant, and this can come with the significant risk of metastasis to other parts of the body along with an early death.

Another veterinary study shows that hyperplastic mammary tissue in dogs has a large number of estrogen and progesterone receptors that suggest a hormonal influence on the mammary cell behavior. This means that spaying and the removal of many of a dogs sex hormones can influence the occurrence of mammary tumors in the future. Because parties argue about whether or not early spaying and neutering of animals is helpful or hazardous to their health, a collection of veterinarians chose to do a spaying versus non-spaying group study.

In a recent study, 84 dogs were diagnosed with mammary tumors and studied. 42 of the diagnosed dogs were spayed at the time of the tumor removal. None of the dogs had mammary tissues removed. After surgery the dogs were tracked for over seven years so that veterinarians could gather information about their health and whether they improved or became ill as a result of the surgery. The veterinarians discovered that 63% of the dogs spayed at the time of tumor removal were tumor-free and 36% of the animals that were not spayed did not develop a tumor.

The study also revealed that the difference in deaths was not significant between dogs that were spayed and dogs that were not. The study also showed that dogs that develop a mammary tumor often developed another one on the other mammary chain later in life. This means that for owners who want to have a preventative mastectomy for their pets, they should remove the tissues on both mammary chains to reduce the possibility of another tumor. Still, only about 36% of all dogs in the study even had a tumor recurrence, so it may be too much of a risk to order a preventative surgery that will cause so much recovery time and anesthetic use.

The relation between spaying pets and the occurrence of mammary tumors suggests that dogs spayed before their first heat cycle only have a .5% risk of developing mammary cancer. This risk increases to 8% when the dog is spayed after the second heat cycle, and owners wait 2.5 years then there is no decreased risk benefit.

This is why veterinarians suggest that early spaying is the best way to reduce the possibility of a mammary tumor in dogs. Veterinarians are still doing research on the effects of early spaying, as some claim that this can put dogs at a greater risk of joint disease and other cancers. If you want more information about mammary tumor removal or need advice about spaying your female pooch, contact a local veterinarian to discuss options!