Cancer and Tumors - Mammary Tumors


Mammary cancer treatment - German Shepherd

Question: Dear Dr. Richards, I hope you can put in perspective conflicting recommendations I have received. While just performing a routine "hands-on" check, I found a small (quarter-size, and not very thick) lump near one of Ursa's breasts, and promptly took her to my vet. He removed the tumor (which could be moved around and wasn't seemingly attached) and sent it to the pathologist. The report confirmed a mammary carcinoma, but the vet said it was "otherwise positive" (no lymph node involvement, ...) and that I had caught it early. My dog is a German Shepherd bitch who was coming into season and who I was about to breed for the third time, he recommended (and performed) an immediate hysterectomy, X-rayed her chest /lungs (which were clear), and then said to watch and wait. He stated his belief that the odds were better than 50 percent that she would have no recurrence. While I regret that she'll no longer be able to do her part to "improve the breed", I will gladly trade that loss for her good health. My quandary is that I have many friends in the sport (Schutzhund), two of whom are also veterinarians, who have told me that I should have had the anterior portion of the mammary chain with which the tumor was associated removed, and a couple suggested following with a round of "chemo" as well. I asked my vet about removing the mammary chain, and he said it would be very painful for (a very active, athletic) dog and would not necessarily be beneficial. So, I accepted his advice, but I want to be sure I am doing what is best for the dog. What is current recommended practice in this situation? Do you agree that her odds are better than 50 percent that the cancer will not recur as it stands? Would those odds likely be improved with mastectomy or chemo? Conversely, if the odds are improved but only marginally, would a mastectomy make it painful for her to work? She is a working dog and she loves to work, so I am not going to subject her to a mastectomy unless it materially improves her odds -- ideally without affecting the quality of her life. Thanks, Richard Answer: Richard- It is easy to find conflicting advise about mammary tumors in dogs. There are actually some good reasons for this. The first is that there are a lot of different types of mammary tumors and there are even subsets of the recognized tumor types. In general, about 50% of mammary tumors are reported to be adenocarcinomas and carcinomas, which are the malignant forms of mammary cancer. An approximately equal number of tumors are benign tumors such as adenomas. In some instances, non-mammary gland origin tumors occur in the mammary glands, such as fibrosarcomas and lipomas. These can be benign, or malignant, as well. In your dog's case, the diagnosis is a mammary carcinoma. There is a subset of this tumor referred to as inflammatory carcinoma, which is considered to be a much more aggressive form of carcinoma. It may be worthwhile to check back with the pathologist to get a more specific impression of what type of mammary carcinoma he thought this tumor might be, although it sounds as if it wasn't an inflammatory mammary carcinoma based on the lack of mention of that in the report. There are several more specific tests to try to determine how malignant a mammary tumor might be, such as steroid hormone receptor status and examination of regional lymph nodes for spread of the tumor (which sounds like it was done already). In general, the best prognostic factors are size of the tumor at the time of removal, whether or not there has been spread to regional lymph nodes and/or distant sites such as the lungs and whether the tumor seemed to have spread beyond the margins of tissue removed. If surgical excision of a small tumor is complete (no invasion of margins) and there is no evidence of metastasis to the lymph nodes or more distant tissues then there is no really good evidence that I am aware of to show that removal of adjacent mammary glands, or the entire mammary chain on one side or both sides, is any more beneficial than lumpectomy alone. Information on cancer changes quickly enough that there is some chance I am unaware of a new study suggesting that more aggressive surgery carries a significant benefit so if you find something solid that suggests that it would be wise to pay attention to it. There isn't a whole lot of evidence to support an increase in longevity associated with the use of chemotherapy in malignant mammary tumors in dogs, either. Most of the stuff I read from oncologists suggests that they do believe that it is helpful, though. There are several protocols that have support, including the use of doxorubicin and taxol. If you do wish to pursue adjunctive therapy (chemotherapy or radiation therapy) it would definitely be best to seek the help of a veterinary oncologist. This is truly one of the specialties in which it is very difficult for a general practitioner to keep up with and to gain adequate experience in dealing with the side effects and complications. In addition, specialized equipment is required for handling some chemotherapeutic agents and for performing procedures such as radiation therapy. Hopefully this helps some. If it just makes for more confusion, please feel free to ask for clarifications. Mike Richards, DVM 1/16/2001

The effect of spaying on future mammary tumors

Question: Thanks very much Dr Richards. Your answer is always so detailed. I am really glad I am a subscriber. I adopted a neo mastiff 3 months ago. SHe is 6 years old and has thyroid problem. The vet said she has to be on medication for the rest of her life (3 pills twice daily). Is that true? Also, is it true that the medication would increase her appetite as she is eating like a pig since then. On examination after adoption, it was found then that she got 13 tumors, mostly mammary. A big surgery has been done to remove all of them in January , and thank goodness they are all benign. Our vet said that it is advisable to spay her, since she is prone to tumors. I have heard that spaying is useful in preventing cancer only when it is done at a young age. Tanya is a big dog (130lbs) and is older too (considering her breed), do you think spaying at this age would still do her some good, or should we just let her stay unspayed, since their life span is 8-10 years. She has survived a big surgery (removal of tumors) in January 2000. Is it worthwhile to have her spayed? Look forward to hearing from you soon. Thanks in advance. Lily Answer: Lily- There have been two recent studies of the effect of spaying on future mammary tumors, once some have occurred, and they have conflicting results. One study reported a protective effect, with about a 15% reduction in future incidence of tumors and the other paper showed no significant difference between spaying and not spaying after tumors are present. From my personal experience there does seem to be some growth in mammary tumors that are already present, associated with estrus cycles. So I tend to think that there is some benefit to spaying, but that it is not a huge benefit. That's unfortunately about as clear as I can get on this particular topic, even though it isn't all that helpful. When a dog on thyroid supplementation starts having signs like a big increase in appetite it is a good idea to check a T4 (thyroxine) level to be sure that it isn't artificially high due to the supplementation. If it is, then the dosage should be lowered. Mike Richards, DVM 3/31/200

Mammary tumor

Question: Dr. Mike, I have a 5 year old female Lab (spayed 3 months ago) who just had a mammary mass removed. She had her first and last liter of puppies (7) in June and was spayed in August. My vet thinks the mass looks suspicious because it wasn't encapsulated and seemed to be an infiltrating tumor. It's been sent off for diagnosis. My question is this. How common are these things and what treatments are available if the diagnosis is cancer? I trust my vet, but I want to educate myself. I don't know if it means anything, but during her pregnancy her milk came in earlier than what the books said (about 8 days prior to delivery) and her breasts were very ropy while she was nursing. She had no problems when I weaned the puppies (5 weeks) and I noticed the mass about a month ago. My vet treated her with a steroid shot and a two week course of Baytril (sp) with no success. That's when we decided to remove the mass. Thanks! M. B. and Hannah Answer: M.- Mammary tumors occur in approximately 25% of female dogs who go through at least two heat periods, whether they are bred or not. Of these tumors, about 80% are benign and simple lumpectomy is sufficient. It is not uncommon for dogs who have one benign tumor to have another one, due to the number of mammary glands present but it is unusual, in our experience, to have to remove more than two or three lumps in a bitch's lifetime. If Hannah is unfortunate and is one of the 20% of dogs who have malignant cancers there have been improvements in chemotherapy for this condition in dogs. It was a good decision to remove the mass and also a good decision to have it examined by a pathologist. Hopefully the odds will work like they should and the news will be good, too. Mike Richards, DVM 12/12/99

Mammary masses and high alkaline phos levels

Q: Dear Dr Mike, Our 13 yr old German Shepard mixed female went in for her annual shots and during the examination the vet found 3 masses in her mummeries; one involving the gland. The dog is in good health; the only evidence of age seems to be arthritis in her hind quarters this started several months ago. We have been treating it with buffered aspirin as needed. Since she was not spayed, the vet recommended that we have the masses removed and spay her at the same time since these tumors are normally hormone related. The vet took a blood to test for both heartworm and for pre-surgery testing. The blood test came back with high levels of alkaline phosphates indicating cushing's disease. The vet indicated that cushing's disease slows healing, so it would be necessary to put her on medication for several months prior to the surgery. The vet recommended that we take her in to a local animal hospital for more extensive bloodwork and for x-rays of the abdominal & chest areas. The x-rays of the chest area are to determine if the tumors have invaded her lungs. I have two questions; I have heard that surgery on older dogs is extremely risky and this dog has had no prior surgeries, so her sensitivity to anesthetic is unknown. Also, at her advanced age would the tumors significantly cut her life expectancy, since the normal life expectancy in this breed is 15-17 yrs? Of course, the quality & comfort of her remaining years is also important. Thank you, Vickie A: Vickie- I have never really understood the logic behind thinking that older animals are more susceptible to anesthetic problems. Personally, I would much rather anesthetize a twelve year old dog with no previous history of anesthesia than a six month old one with the same history. Just the fact that the dog lives to be twelve or thirteen years old is a good sign that its body works well and is not likely to have a serious hidden defect that would lead to sensitivity to anesthesia. The veterinarians who claim that older animals are at an increased risk of anesthetic complications believe that as a pet ages it is more likely to accumulate problems such as heart valve insufficiencies, kidney damage or liver damage which make anesthesia a greater risk. I have repeatedly asked veterinarians which patients die most frequently from unexplained anesthetic crises and virtually all of them have lost a patient during a spay procedure, an ear crop or some other pediatric surgical procedure and very few can remember an incidence of anesthetic death in an older pet. Surgical deaths are more common in this age range because the surgeon is less likely to be doing a routine procedure on healthy tissue but I strongly question the assumption that there is an increased risk of anesthetic death in an older patient with normal clinical signs other than a problem such as mammary cancer. Particularly if the better anesthetic agents are used. It is probably best to take lung X-rays and be sure the tumors haven't metastasized prior to surgery. Canine mammary tumors are benign most of the time but it is still a worthwhile precaution. Mammary tumors grow unpredictably in size in dogs. Some stay small for long periods of time and other grow so rapidly that it kills the tissue around the tumor and necrotic abscesses form. In most cases, your dog will enjoy a much higher quality of life without the tumors. Since mammary tumors seem to enlarge under the influence of the reproductive hormones it is best to spay a bitch at the time of mammary tumor removal. While there is no sure way of knowing it is very likely that tumor removal could extend her lifespan. Rises in alkaline phosphatase levels can occur for a number of reasons and Cushing's disease is only one of them. If this is the only abnormality on labwork it probably wouldn't deter me from doing surgery but a more complete workup is not harmful and may be helpful. Again, age is not a major factor in anesthetic safety. Preanesthetic examination and labwork are likely to uncover any hidden problems that may impact on anesthesia such as kidney disease or diabetes that are more common in older dogs. As long as the exam and tests seem normal there should be no significant increase in risk in anesthetizing an older patient. Mike Richards, DVM

Mammary cyst

Q: Hi Dr. Mike: We have a 7-year-old Chihuahua.. She was never spayed . We took her to the vet recently and she and was diagnosed with a cyst in her breast and a false pregnancy. I understand this happens when dogs haven't been spayed. Since it was diagnosed last month, the cyst seems to be getting bigger. The vet recommended removing the cyst and a possible masectomy. I have heard that the cysts can come back and/or are better left alone sometimes (at least in cats). What is your opinion? Also, does anyone subsidize spayings. I understand Friends of Animals used t A: A cyst in the mammary gland region is very likely to be mammary gland cancer. In dogs, mammary cancer is usually benign and the current "standard" recommendation is to remove the lump and any visibly affected tissue in the region of the lump. This may be the mastectomy procedure your vet is referring to. In the past the recommendation was to remove all the mammary tissue on the affected side, which would be a more radical mastectomy and is usually not recommended anymore. Mammary tumors are a lot easier to remove when they are small and they will sometimes grow rather rapidly. It would be best to talk to your vet about getting this lump removed and to follow his or her advice on the matter. Mike Richards, DVM

Mammary tumor possible

Q: Dear Dr. Mike, I am asking these questions on behalf of a friend who does not have Internet access so please forgive me if they do not seem entirely logical. She has three Jack Russell bitches (spayed mother and two 'whole' daughters). The problem affects one of the daughters - Poppy - aged 11. Poppy has a subcutaneous cyst in one of mammaries nearest her tail which is currently being treated orally with cortisone. Without the cortisone the cyst becomes large and 'angry' looking. The treatment has diminished the cyst but it is still there. She has been on continual treatment for about three weeks so far. Is is safe to continue the cortisone treatment or should the cyst be removed surgically? The dog is in excellent health otherwise. Seven years ago, Poppy had a cyst in an upper mammary (same side as current one) and the complete mammary gland and nipple were removed (surgery undertaken in the UK). Also, she was treated with cortisone for dermatitis about six months ago but treatment ceased after the condition improved. A possibly related question involves Poppy's appetite. This has increased dramatically (with a corresponding increase in weight) from about the time the cortisone treatment started. Her stomach feels tight and firm but not distended. Is this a normal reaction to cortisone or is it more likely to be something else and the timing coincidental? We live in Kuwait and pet veterinarians are few and good reliable ones rare, so any help and advice you can offer will be greatly appreciated. Thank you and regards, N. & S. A: Cortisones almost always cause an increase in appetite, drinking and urination. So the signs seen in Poppy are an expected side effect. Mammary tumors are very common in intact (not spayed) dogs, affecting about 25% of older female dogs. The location makes this very likely. Most mammary tumors in dogs are benign but they often do get infected or grow rapidly enough to cause tissue necrosis and look very angry. It is very likely that this is the problem. Unfortunately, there are many other possible problems, including abscess from another reason, sebaceous cysts, skin infection, etc. In general, I would want to identify the cause of the cyst if possible. If this can be done by aspiration (works for sebaceous cysts and some tumors) removal may not be necessary. If not, I'd vote for removal unless your vet knows for sure what the lesion is without doing that. Mike Richards, DVM


Michael Richards, D.V.M. co-owns a small animal general veterinary practice in rural tidewater Virginia. Dr. Richards graduated from Iowa State University's College of Veterinary Medicine in 1979, and has been in private practice ever since. Dr. Richards has been the director of the PetCare Forum...