This is a carry over from my previous Blog Post on "Lumps, Bumps, Masses, Tumors, and Cysts." I wrote on the removal of a mammary or breast tumor from one of our female veteran Irish Wolfhounds (8.5-year-old), and the biopsy test is back. Indeed, the results are that the tumor was mammary adenocarcinoma. Naturally, many people at this point may panic or, at the least, are profoundly concerned. I have spoken with my general surgeon, and the recommended course of action is to watch the site where we excised the tumor and its surrounding tissue and also her other mammary glands as well by gently massaging the areas frequently to feel for small pebble-like masses. Further, my surgeon explained that sometimes a resected adenocarcinoma could turn serious and affect internal organs, but that, in his experience, seems to be pretty rare. Usually, if it returns, it will be in the mammary tissue.

According to the American College of Veterinary Surgeons (ACVS),

"More than a quarter of unspayed female dogs will develop a mammary tumor during their lifetime. The risk is much lower for spayed female dogs, male dogs, and cats of either gender. In female dogs, 50% of mammary tumors are benign, and 50% are malignant. However, few of the malignant mammary tumors are fatal.

Additionally, ACVS states that if the mammary tumor is malignant (such as my Wolfhound's breast tumor), the surgical site and regional lymph nodes should be checked for local tumor recurrence and metastasis, as my surgeon already explained, but also abdominal ultrasound and chest radiographs are recommended every 3–6 months to assess for evidence of metastatic disease.

The ACVS goes on to explain:

In dogs there are a number of factors that influence the prognosis following surgery. These prognostic factors include tumor size, clinical stage (how far the cancer has spread in the body), tumor type and grade, and various other pathologic changes seen in the tumor tissue. Benign tumors are cured by surgery, although the development of new mammary tumors (both benign and malignant) is possible. There is a poorer prognosis with malignant mammary tumors, and it also depends on what type of cancer. In dogs, the size of malignant mammary tumors is an important consideration when determining prognosis, both for local tumor recurrence and survival time. The smaller the mass is at the time of surgery (3–5cm or smaller) the less likely it will recur, or metastasize (spread) elsewhere. Dogs can live several years after complete removal of some malignant mammary tumors. So once a mass is found, having surgery to remove it earlier is better.

Keep that last piece advice foremost in mind as although we discovered her mammary tumor several weeks prior -- it grew to a size of a sea scallop in a relatively short time frame before it was excised. It is important to reiterate that mammary tumors are not necessarily always malignant, and some could be due to a highly glandular location. Even in the case of our female's tumor -- although adenocarcinoma was determined by a biopsy -- the rate of growth does not inevitably mean that hers has already metastasized. The rate of growth might also be due to the glandular region. Only time will tell.

One last thought, interestingly, data has revealed, according to ACVS but also other investigative research that in dogs, obesity at a young age is a risk factor.