What are the signs that my dog may have a mast cell tumor?
Mast cell tumors of the skin can occur anywhere on the body and vary in appearance. They can be a raised lump or bump on or just under the skin, and may be red, ulcerated, or swollen. While some may be present for many months without growing much, others can appear suddenly and grow very quickly. Sometimes they can suddenly grow quickly after months of no change. They may appear to fluctuate in size, getting larger or smaller even on a daily basis. This can occur spontaneously or with agitation of the tumor, which causes degranulation and subsequent swelling of the surrounding tissue.
When mast cell degranulation occurs, some chemicals and compounds can go into the bloodstream and cause problems elsewhere. Ulcers may form in the stomach or intestines, and cause vomiting, loss of appetite, lethargy, and melena (black, tarry stools that are associated with bleeding). Less commonly, these chemicals and compounds can cause anaphylaxis, a serious, life-threatening allergic reaction. Although very uncommon, MCTs of the skin can spread to the internal organs, causing enlarged lymph nodes, spleen, and liver, sometimes with fluid build-up (peritoneal effusion) in the abdomen, causing the belly to appear rounded or swollen.
How Vets Diagnose Tumors in Dogs
One way your veterinarian cannot diagnose a tumor is by looking at or feeling it. Frequently, clients want a veterinarians opinion on a mass on their dog but then do not approve diagnostics, perhaps because of cost. Watching a mass to see if it changes or bothers your dog is generally a bad idea, as these are not necessarily signs that a mass is benign.
Your veterinarian can have an idea of what they think a mass is but will not be able to give you a definitive diagnosis without sampling. General lab work can often point toward an organ system that needs to be examined closer but rarely provides a confirmed diagnosis of cancer.
Sampling a tumor is often the best way to diagnose a tumor. The larger the sample, the more accurate the diagnosis will be. Tumor samples can be obtained with a procedure called a fine needle aspirate. During this procedure, a small needle is used to remove a small group of cells from a mass. This procedure can frequently be performed at the same appointment and is minimally invasive.
The downside of a fine needle aspirate is that your sample may not be fully representative of the type of tumor being sampled, and the veterinarian cannot get any information about the layout of the cells, which can help with diagnosis.
Tumor samples can also be obtained with a biopsy. A biopsy can be excisional (the entire tumor) or incisional (a small portion of the tumor). A biopsy will typically require general anesthesia or heavy sedation but can provide more information to help with diagnosis and can sometimes remove the tumor completely.
Biopsies can sometimes be achieved externally but more often are performed surgically when the veterinarian performs an exploratory surgery.
Endoscopy can be used to collect samples as well, similar to a colonoscopy in people. Bladder tumors can be sampled via a urinary catheter or with a routine urinalysis.
Internal tumors are sampled in similar ways but with more complicated methods. Tumors in the abdomen (liver, spleen, kidney, bladder, etc.) can be sampled with a fine needle aspirate that is guided by ultrasound.
Different types of cancer have different treatments. The treatment recommended for a dog’s tumor depends on several factors:
Treatment options include surgical removal, radiation, immunotherapy, and chemotherapy. Several herbal remedies have also been used successfully to help either with the symptoms of a tumor or with its growth. Even changes in diet can help with cancer treatment in dogs.
Laura D Garrett Department of Veterinary Clinical Medicine, University of Illinois College of Veterinary Medicine, Urbana, IL, USA Abstract: Mast cell tumors (MCTs) are the most common malignant skin cancer in dogs, and significant variability exists in their biological behavior. Most MCTs are cured with appropriate local therapy, but a subset shows malignant behavior with the potential to spread to lymph nodes, liver, spleen, and other areas and to thus become a systemic cancer. Because of this variable behavior, it is difficult to predict how any individual tumor is going to behave. The variability thus creates uncertainty in deciding what a particular dogs prognosis is, whether staging tests to assess for metastasis are needed, and even what treatments will be necessary for best outcome. In addition to controversies over the potential for development of systemic disease, or diffuse metastasis, controversies also exist over what treatment is needed to best attain local control of these tumors. This article will briefly discuss the diagnosis of MCTs in dogs and will summarize the literature in regards to the controversial topics surrounding the more aggressive form of this disease, with recommendations made based on published studies. Keywords: mitotic index, mastocytosis, tyrosine kinase inhibitor, histologic grade
MCTs can be located anywhere on the body and may lie within the dermis and/or subcutis. They have a wide range of gross appearance, from raised and superficial to very deep and fixed; they may feel soft and fluctuant or firm. Most MCTs are easily diagnosed with fine needle aspiration (FNA). Infrequently, MCT granules will not stain with Diff-Quik (Jorgensen Laboratories Inc., Loveland, CO, USA) and need to be stained with a Wright’s stain. On Diff-Quik cytology, if eosinophils are seen along with large round cells that lack granules, suspicion should be raised for an MCT and the slide submitted to a clinical pathology laboratory for a non-Diff-Quik stain.5
The majority of MCTs will be cured with surgical excision.1 Prognostic factors for predicting MCTs that will exhibit a more aggressive biologic behavior – ie, tumors that will not be cured despite local excision and that will ultimately lead to the patient’s death – are varied as well as controversial. When to pursue staging tests in dogs with MCTs, which tests to perform, and treatment recommendations beyond surgery are based on the predicted biologic behavior of the tumor, with staging diagnostics and systemic therapy the recommendation for dogs with biologically aggressive MCTs.
In general, staging tests for asymptomatic dogs with cutaneous MCTs are extremely low yield. The test most often positive is regional LN aspiration. Cytologic assessment of the locoregional LN is important, even if the node is not enlarged. In a study of dogs with muzzle MCT, four of eleven LNs with metastases were of normal size.19 Another study with 55 dogs with confirmed LN metastasis and 35 dogs without metastasis showed a sensitivity of 71% and specificity of 54% for palpation as a predictor of metastasis.34 Sixteen of 35 dogs (46%) with normal size LNs on physical examination had metastasis, whereas in another study eight out of 21 (38%) normal size LNs showed metastasis.35 FNA of the LN is ideally performed prior to excision of the primary MCT, as surgical treatment of the tumor can produce confusing LN results due to local postoperative inflammation. As mast cells can be a normal feature in LNs, some MCT cases will not have a definitive answer on LN cytology. Criteria for LN involvement have been proposed and used in several subsequent reports.34–37 Prognostically, the implication of a metastatic LN is also a controversial topic. LN involvement has been associated with a worse prognosis in a number of studies.20,36–39 However, several papers also report long-term survival in dogs with LN involvement where the primary tumor and the LN are treated to achieve local control using surgery with or without radiation therapy.14,34,35,40,41 Chemotherapy was used in many of the reported cases as well, although the protocols varied, and the added benefit of chemotherapy after local control was achieved cannot be proven via the retrospective noncontrolled studies that currently exist. To summarize the information in the literature, LN involvement may carry a worse prognosis, yet dogs can still have prolonged survival with adequate treatment of the primary tumor and the metastatic node, with chemotherapy potentially having a benefit as well. Assessment of any locoregional LNs, whether normal sized or enlarged, with cytology or histopathology is critical to determine the stage of the tumor and appropriate therapy for the patient.
Although surgery is the mainstay of therapy for MCTs, and is curative in a large percentage of cases, there is still much controversy over surgical margins. Removing the tumor with gross margins of 2–3 cm lateral margins and a deep margin one tissue plane beyond the tumor has been recommended. Twenty-three MCTs in 21 dogs were evaluated for completeness of excision at 1 cm, 2 cm, and 3 cm from the tumor edge; 100% of tumors had complete excision at the 2 cm margin mark. Only grade I (three) and grade II (20) MCTs were in the study, so it is not clear whether 2 cm margins will be adequate for grade III tumors.49 In a subsequent study, 91% (21/23) of grade I and II tumors were completely excised with 2 cm margins and had no local recurrence for >538 days.50 Thus, 2 cm margins provide good results for grade I and II MCTs, with decreased morbidity. A recent publication described 40 dogs with cutaneous (87%) and SQ (13%) MCTs treated with a modified proportional margin approach.51 Tumors were resected with a lateral margin equal to their widest diameter, with a maximum lateral margin of 4 cm, and with a minimum depth of one fascial plane deep to the tumor. Gross surgical margins obtained ranged from 5 mm to 40 mm. Tumors ranged in grade and included 51% grade I, 44% grade II, and 5% grade II; with the two-tier system 90% were low grade and 10% high grade. Complete excision was obtained in 85% of tumors, whereas 15% had dirty margins. Only one tumor regrew locally; the median follow-up time for the dogs was 420 days. This novel approach to MCT surgical margin excision with individual tailoring for the patient appears to provide good outcomes; validating studies are warranted.
⚕️ 8 TYPES of TUMORS (Cancer) IN DOGS and Affected Breeds
Theres hemangiosarcoma, which is a cancer of your spleen and your liver. And there are certain breeds we see that in. Sometimes we tend to see it more in German Shepherd dogs, Golden Retrievers, and Labrador Retrievers. Any dog can, of course, present with this kind of cancer, but there are a few breeds that tend to be overrepresented. There are also many skin-type cancers. Mast cell tumor is a prevalent one that we see. Its a skin cancer that tends to be solitary, but there can be multiple nodules in the skin. And on occasion, it can be quite aggressive, so catching it early is essential.
We see a variety of different tumors, including squamous cell carcinomas, which is a tumor of the skin and the mouth. We see melanomas on the skin and in the mouth. Male dogs get testicular tumors, and mammary tumors are prevalent in female dogs that have been spayed later in life. Osteosarcoma is a very aggressive malignancy of the bones. We see lymphoma, a cancer of basically the lymph system or the lymph nodes, part of the immune system, just like in humans. We also see bladder tumors. Again, we see all kinds of cancer in dogs.
Sometimes you can see simple things like weight loss and lack of appetite. There are many lumps, and bumps dogs can get. Most of them are benign, but still, without checking them and running a straightforward test called a fine needle aspirate, we dont know for sure.
Most cancers are more amenable to being removed like tumors. And if theyre detected earlier, when theyre smaller, theyre less apt to have spread. If you catch them early, you can either treat them with surgery or chemotherapy, depending on the tumor types. Not having the cancer spread and even cure rates and things like that are often based on how soon its caught.
Fine needle aspirate is where we stick a needle in a solitary tumor, for instance, or multiple tumors that we can see and feel. And then, we take that sample, put it on a slide, and look at it under the microscope. Sometimes that in and of itself is diagnostic. Sometimes we sedate the pet, and we take a little piece of the lump or bump, and we send it to the laboratory, and they do whats called histopathology on it. They analyze it and give us a diagnosis of what it is and sometimes how aggressive it is. In some cases, we remove the whole tumor and do histopathology. They can let us know whether it had reasonable margins, or whether we got it all, and what its recurrence rate might be. Sometimes we can diagnose cancer with things like x-rays and ultrasounds. We can find it and see it, for instance, if we x-ray the chest and see multiple tumors in there. Thats an indication that that dog has metastatic disease, so we start looking for a primary tumor somewhere else.
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Dog cancer can be cured. It depends on the type of tumor, its location, and other things like that. As far as chronic diseases go, theres a number of them in dogs, cats, any animal. Cancer is the most likely to be cured or have a reasonable treatment.
Thats hard to say because it depends on the type of tumor. I dont know that we have an answer for that. There are certain tumors like sarcomas, for instance, that tend to be a little more locally aggressive. If we were able to surgically remove them, that would be a high cure rate for that type of tumor. Then there are other tumors like bone tumors that are extremely aggressive, and we dont cure the dog. We make them feel comfortable for an extended time, sometimes with remote amputations and things like that.
Yes, there have been. We do chemotherapy as they do in humans and they do radiation therapy like they do in humans. There have been all kinds of neat immunotherapy or antibody therapy advancements where you have antibodies that can attack the tumors. Theres been a lot of advancements in cancer that werent available 20 years ago.
It is with many types of cancer. It depends on the type of cancer, but with certain tumors like mast cell tumors, we can remove them. Depending on the location of sarcomas, we can remove them. Many times, those are curative surgeries. Surgery is often an excellent option for many different types of cancers— not all of them, but many of them.
It depends on several things. Sometimes we can figure out what type of cancer a dog has based on a fine needle aspirate, where I stick a needle into a tumor, for instance, and look at it under the microscope. Certain tumors are relatively easy to diagnose that way, like a mast cell tumor in the skin is an easy one to diagnose that way. We can diagnose some of them in the office. For others, we take a biopsy sample. We take a little piece or the whole tumor in some cases and send that to the laboratory. A veterinary pathologist looks at them and does histopathology and gives us that diagnosis.
No, not necessarily. Pretty much every cancer has treatment options, and that ranges from curative surgery to palliative therapies where we keep them comfortable for long periods. Some tumors arent resectable, or surgery is probably not going to remove the cancer, but its slow-growing, and we can keep them comfortable for a very long time. And to dispel the myths, we do compassionate cancer care with dogs and cats. We dont want them to feel bad while theyre going through chemotherapy, and most dogs and cats do very well on chemotherapy. Theres often a protocol for the individual dog, the owners budget, and the owners schedule to make the dog feel a lot better and extend their life.
Its tough to say, and its a very personal decision every owner has to make. My advice is when your dog is having more bad days than good days or when your dog stops doing the behaviors that make them happy. Thats often their interaction with their owners or their pack members. It may be that its getting time, at that point, that the dog doesnt feel very well and may be getting close, but that is a decision typically thats between you, your family members, and your veterinary team. We have that discussion to see when everybody thinks its time.
We do a lot of palliative therapy. We control nausea. We dont want our patients to feel any pain, and we want to have the most positive end-of-life experience between the owner and the patient. We try to make things as painless and as pleasant as it can be in those situations.
I would say they can get most of the same types of cancers that humans get. Im not too versed in how many different types humans get, but for instance, lymphoma humans get, so many dog owners are familiar with that. Breast cancer, a lot of owners are familiar with that. Dogs can get that. There is some that overlap.
Dog lymphoma is a cancer of the lymphocytes, which are an immune cell in the body. They live in the lymph nodes and produce antibodies. The most common lymphoma is where the lymph nodes become rapidly enlarged throughout the body.
Melanoma is melanocytes or pigment cells that have unchecked division rates, and they get masses. For the most part, we see more melanomas in the dogs mouth area, sometimes around the toenails and around the rectum. Theyre not necessarily based on UV radiation and light like they are with people in the skin. Thats not as common in dogs. They have a nice haircoat. I think thats part of it. We tend to see them in the mouth or the oral cavity and things like that.
A dog tumor is an inappropriate proliferation of cells. A cell population goes unchecked. They can be tumors in the skin, under the skin. For instance, fat is a common benign tumor called a lipoma in dogs. Well commonly see that, and theyre not always cancerous. Any cell line that decides it wants to divide at an unchecked abnormal rate.
It depends on the tumor. Some are soft and squishy and round like a lipoma. Youll find those in Labrador Retrievers under the skin many times. Some of them are very firm and hard tumors in the skin. Youll see that in certain sarcomas. With bone tumors, youll see very painful swelling. It just depends, but for the most part, most owners are finding lumps and bumps on the dog, and thats what brings them to me.
A tumor that bleeds has often been traumatized by the dog itself, bumped, or something like that. Some tumors outgrow their blood supply and then well have a center that weakens in the middle because it doesnt have enough blood, and it ruptures out. Use compresses or wrap it and then seek veterinary attention. Well talk about options as to whether it can be surgically removed at that point.
I would say surgery is probably the most common treatment option for most. Then we have some tumors that tend to be more aggressive and metastatic. Those will need chemotherapies, and as we had talked about earlier, chemotherapy does not typically make animals sick and feel awful. People think it does in humans, so thats not typically what we want for their last days, months, or years on earth. We want compassionate care. Then radiation therapy is also very common. In tumors like melanomas, for instance, we can sometimes remove them and then do immunotherapy or antibody therapy or vaccine therapy. There are all kinds of things out there that we can do.
Some chemotherapy agents can cause changes in the blood parameters and decrease the immune system transiently. Those patients are monitored to make sure that their body is safe to have the chemo. Thats one side effect, and you can get nausea with certain chemos, but we try to combat that ahead of time with anti-nausea agents.
There again, it depends on the individual case. It depends on how aggressive or advanced the particular cancer is. By the time its detected, some dogs will live weeks to months, while others will live for years. Lymphoma patients, for instance, can live several years.
It depends on the tumor. For instance, sarcomas tend to be locally aggressive tumors of connective tissue. Some dogs will live years with those with supportive care and palliative therapy. It depends on the type of tumor that were dealing with or the type of cancer were dealing with, where it is, how big it is, and things like that.
What you would see is they will stop eating for days. They start not doing the behaviors they usually do in interacting with our owners and things like that. Dogs tend to be very social critters with their owner. When they stop caring about their family members, sometimes its a sign that theyre not feeling well.
Thats very individual. Surgery is pretty much the mainstay for many tumors. That would be the one you would choose. Chemotherapy, for instance, often depends on the owners budget and schedule. I always encourage owners, if they are very interested, to seek a consultation with an oncologist, and they can give you options. There are often options for every budget and every schedule available—not always, but many times there are. You can at least get that consultation to know what your options are.
Pet insurance and twice-yearly exams can help. Then we notate any lumps and bumps that we find. We notate their size. Weve done fine needle aspirates, and we have those results logged on records. Its easier for us to detect if things are changing. There are certain benign lumps and bumps where its OK to monitor and not do anything about. If theyre changing, then we start talking about options to investigate further.
Yeah. There are many different medications, as chemotherapeutics are medications. Certain tumors like bladder tumors respond to medicine to some degree, or it slows their spread and increase in size. Nonsteroidal anti-inflammatories like Rimadyl can also help with those tumors. Studies show a good quality balanced nutrition and leaner body weight put an animal at lower risk of cancer.
It depends. Surgery is often curative, and so thats the day of surgery and healing, and its done. With chemotherapy agents for lymphoma, the treatments can vary. Some of them can last many months until the pet goes into remission. Then when they come back out of remission, they start over. It depends on the tumor.
In response to treatment, theyll go into a remissive state. A lot of those chemo protocols are done at that point or a little past that. Then we monitor the dog very closely for them to come out of remission. Then a new protocol is started at that point.
We try for it not to be. Our rules are, we dont want anybody in pain. We dont want anybody sick, and we dont want anybody starving. We want them to eat. We want them to feel good.
Early detection is probably our biggest factor; hence annual wellness or semi-annual wellness are excellent things to do.
If you still have other questions and youd like to reach out to us, you can call us directly at (704) 872-3625, you can email us, or you can reach out on Facebook. But please do reach out, and well get back to you as soon as we can.