My Old Dog with Kidney Disease needed Surgery:
When Lady was 14 years old, I discovered a hard mass in one of her mammary glands. Lady has many lipomas that, while unsightly, are harmless; they bother us way more than they bother her! This newly discovered mass felt different, so when she was in for bloodwork I brought it to the attention of my vet. Upon inspection, the vet immediately recommended having it removed as it was a mammary tumor. Without a biopsy, we would not know whether the tumor was malignant or benign.
I wanted to have the mass removed as much as Lady’s vet did, but putting Lady through surgery scared me because of her advancing age and her chronic renal failure.
Before looking into what I did for my dog after discovering she had a mammary tumor, it is helpful to know more about what mammary tumors are, how they are treated, and what the prognosis is after treatment.
What are Mammary Tumors?
As their name suggest, mammary tumors are tumors that grow on the mammary glands. Interestingly, these tumors are actually very common in female dogs, with unspayed females having over a 25% chance of developing one in their lifetime. To put this in perspective, The Dog Owner’s Home Veterinary Handbook compares a dog’s chance of developing a breast tumor to a person’s chance. An unspayed female dog is 3 times more likely to develop a breast tumor than a woman. Mammary tumors in dogs have roughly a 50% chance of being benign (harmless) and a 50% chance of being cancerous. (The Dog Owner’s Home Veterinary Handbook, 4th edition).
Hormones appear to play a role in whether or not a female dog will get a mammary tumor in her lifetime. A female dog that is spayed before her first heat has a less than 1% chance of getting breast cancer (The Dog Owner’s Home Veterinary Handbook, 4th edition). Spaying after the first heat cycle but before her second puts her at an 8% risk, according to the same source. After two heat cycles, the above text states that there is no reduction in risk of a mammary tumor. I have read other sources that differ slightly in their statistics, but most fall around these numbers.
If the tumor is malignant, it can spread throughout the body as any cancer can given the chance. Tumors may have discharge and if allowed to continue growing may ulcerate. A tumor that breaks through the skin’s surface is considered an ulcerated tumor (“About Ulcerating Cancers”).
Note: There is another type of cancer called inflammatory cancer that can occur in the mammary glands. This isn’t what we are looking at here.
How to Prevent/Detect Mammary Tumors in my Female Dog:
As can be seen, the best way to prevent your female dog from developing a mammary tumor in her lifetime is to spay her before her first heat cycle. Lady was not spayed until she was an adult. Many shelter dogs like her aren’t spayed until they are adults, so it is important to check your female dog who is either unspayed or was spayed after going through a heat cycle regularly for breast tumors. This is especially important after the age of 6, although it never hurts to start keeping an eye out for issues at an earlier age. As with people, early detection is extremely important to improve chances of successful treatment. If you feel any lump or swelling, take your dog to the vet for a checkup.
How do I Know if my Dog’s Tumor is Benign or Malignant?
I have had pets get needle aspirations to check lumps and bumps many times. With mammary tumors a needle aspiration is not a reliable way to determine whether or not the tumor is malignant. The only way to determine this is to biopsy the mass and have it tested.
Treating Breast Tumors in Dogs:
As stated above, early detection is crucial to good prospects of recovery. If the tumor is malignant but is removed when it is an inch or smaller, the cure rates are favorable (The Dog Owner’s Home Veterinary Handbook, 4th edition). Benign tumors are completely taken care of by removing them. Chemotherapy generally doesn’t seem to be really beneficial for dogs with breast cancer, but every case is unique, and it may be recommended for your dog (“Mammary Tumors”).
Before getting surgery, I would recommend asking to have x-rays taken of your dog’s chest. Breast tumors often metastasize to the lungs. If there are visible signs of cancer having spread to the lungs, I don’t see the point in putting the dog through the stress of surgery since the cancer has already become invasive throughout other parts of the body.
Now, let’s look at Lady’s circumstances, and how I made the decision to have the surgery even though she was a senior dog with kidney disease.
Lady’s Signs and Symptoms:
- Size of tumor – 2 cm (0.79 inches)
- Mammary tumors are generally not painful
- Lady has a history of high blood pressure that medication failed to improve.
- Kidney disease
- Creatinine 1.9
- BUN 33
- Low urine specific gravity (meaning her kidneys cannot concentrate urine as much as they should. I did not know Lady’s exact number, but my vet said it put her in the category of late stage kidney disease. Her other numbers did not line up with this)
- All other values, such as phosphorus, were normal at the time of her surgery
Other than her kidney disease, Lady was in good condition when we discovered her mammary tumor. I think it is truly important to look at an elderly dog’s physical condition and not just her age when deciding if surgery is a good option. Some 13-year-old dogs may handle surgery better than some 8-year-old dogs. Lady’s kidneys weren’t great, but they were not that bad either. If her creatinine and BUN were more elevated and she had high phosphorus or other issues, my decision may have been different. Both Lady’s vet and I agreed that Lady’s constitution was good, and that there was more risk in leaving the tumor than in removing it.
Before surgery x-rays were performed to check to see if there were signs of metastasis. We also had the x-rays to check Lady’s heart. She had began coughing in the previous months, and her cough sounded frighteningly like the cough of a dog with congestive heart failure. The x-rays showed no problems with her heart (had there been a problem, I would not have had the surgery because the risk would be too great).
Before, during, and after the surgery Lady received continuous IV fluids to help her kidneys as much as possible. Her vet only removed the mammary tumor. I mention this because Lady has a harmless cyst on her ear that is rather ugly, but removing it would mean longer time under anesthesia. For a dog with kidney disease, it is important to minimize the time the dog is under as much as possible, so purely cosmetic procedures should be skipped.
Lady stayed at the doctor’s office for several hours after the surgery. We brought her home that afternoon and followed the instructions for the medication she received. Her vet prescribed tramadol and Tylenol. Other drugs are often used for post-surgical pain, but we were limited because of her kidney problems. The after effects of anesthesia make Lady extremely restless, so I was up with her throughout the entire night, but by the morning her personality was back to normal.
After the results from the biopsy came back, our vet called us with the news that Lady’s tumor was indeed malignant. The vet believed all the cancer was removed during surgery, but we were given information on a veterinary oncologist who worked with chemotherapy in case we wanted to pursue such treatment. Chemotherapy hasn’t been shown to improve survival rates in dogs with mammary cancer. This, in addition to Lady’s problematic kidneys, made my decision not to pursue chemo easy. Over six months later, Lady is now 15 and doing quite well.
Making the decision to have surgery on Lady was extremely stressful, but it came down to weighing the benefits against the risks. Leaving the tumor to grow, not knowing if it was cancerous or not, seemed more dangerous than putting her kidneys through anesthesia. If your dog has kidney disease and needs surgery, work closely with your vet to decide if surgery can be performed safely.
The Dog Owner’s Home Veterinary Handbook, 4th edition
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