5 Common Cancers in Dogs


In this article I shall describe five common cancers found in dogs. I’ve included some of the symptoms of these cancers and you will see that many of them are also included in the 10 common signs of cancer in small animals that I listed in the last article.

The prognosis for the cancers I mention is not particularly good; the figures are broad generalizations, but they do highlight how important it is to to detect and treat cancer as early as possible to give your dog every chance of a successful recovery or good remission prospects.

Before we start, here are two more definitions; cancer can be divided into two broad categories:

  1. Carcinomas – malignant growths made up of epithelial cells (these are the cells that cover the lining of any body surface, such as skin, the bladder and blood vessels) that pass into the surrounding tissues and give rise to metastases (the spread of cancer cells);
  2. Sarcomas – malignant tumors that originate from connective tissue (such as bone, cartilage, muscle, blood vessels and lymph tissue). There is usually a prefix that describes the tissue of origin, for example, osteosarcoma is cancer of the bone.

Here is a list of 5 of the most common forms of cancer in dogs, and their symptoms:

1. Lymphosarcoma (Lymphoma)

This cancer is associated with your dog’s lymphoid system, which is an important part of his immune system.

Lymphoid tissue is found in many parts of the body including the lymph nodes, liver, spleen and skin. The most common form of lymphoma in dogs is the multricentric form that occurs in the lymph nodes.

Symptoms of lymph node cancer are swellings of the lymph nodes, and there are 5 major lymph nodes that you can feel on your dogclick here for a diagram showing the location of the external lymph nodes.

Other forms of lymphoma will show symptoms such as vomiting, weight loss and lack of appetite (gastrointestinal form), shortness of breath (chest form) and single or multiple lumps in the skin or in the mouth (skin (cutanaous) form)).

Middle aged to older dogs (aged approximately seven to ten years) are more prone to lymphoma, and no breed is particularly susceptible. The cancer can be very aggressive, and if left untreated the prognosis is a matter of weeks. With treatment your dog’s life can be extended by several months to a year.

2. Hemangiosarcoma

This cancer originates from the cells that form your dog’s blood vessels and can occur in any part of your dog’s body, but is mainly found in the spleen, liver, heart and skin.

The first sign of the cancer being present is usually a ruptured tumor, and because the tumor is formed from blood vessel cells, it is often full of blood.

If the tumor is in the liver or spleen, the ruptured tumor will cause anemia and weakness in your dog through the loss of blood.

If the tumor is present in your dog’s skin, then a lump may be felt under the skin, and if it’s in the bones then a swelling of the bone may be felt.

Hemangiosarcomas usually occurs in older dogs, and some breeds seem to be predisposed to it – Golden Retrievers, German Shepherds, Portuguese Water Dogs and Skye Terriers.

The tumors aren’t usually detected until their late stages, in internal organs this is usually when the tumor has ruptured, and the prognosis is poor; less than 50% of dogs will survive more than 6 months. Survival rates are better when the cancer occurs in the skin because it can usually be detected and treated earlier.

3. Osteosarcoma

This is cancer that originates in your dog’s bones, more usually in the limbs but can occur in any part of the skeleton.

Large dog breeds are more prone to osteosarcoma – Great Danes, Saint Bernards, Great Pyrenees, Newfoundlands, Bernese Mountain Dogs, and Irish Wolfhounds in particular. Heavily built dogs such as Rottweilers, Labradors, Golden Retrievers, German Shepherds, Dobermans, Weimaraners, and Boxers are also at an increased risk.

The symptoms include lameness, pain in the bones, swelling, and reluctance to exercise. 90% of osteosarcomas spread to the lungs and so your dog may show symptoms such as coughing and difficulty in breathing too. Unfortunately the cancer is rarely detected before it has spread from the bones to other parts of the body.

The prognosis is poor; less than 50% of dogs will survive more than a year.

4. Mammary Carcinoma

Mammary tumors are the most common tumor in female dogs that haven’t been spayed – the risk of your dog developing this cancer is almost eliminated if she is spayed before her first season.

Provided the tumor is detected early enough, this cancer can usually be successfully treated. The symptoms are a solid mass or numerous swellings in the mammary glands; they tend to start off small and grow quickly grow in size.

As the cancer can spread to other parts of your dog’s body, any unusual swelling in the mammary glands should be investigated by your vet as soon as possible so that any malignant tumor can be treated.

5. Mastocytomas (Mast Cell Tumors)

Mast cells form part of the body’s tissue and play a role in the body’s immune system.

Mastocytomas are most commonly seen in the skin, and can spread to the lymph nodes, spleen, liver and bone marrow. These tumors usually occur in older dogs.

Symptoms include raised masses on or under the skin – single or multiple lumps, which may be smooth, bumpy or ulcerated. Your dog may also show a lack of appetite, vomiting and abdominal pain.

The prognosis depends upon how far advanced the cancer is; broadly if the tumor is on your dog’s limbs then he has a better prognosis than if the tumor is in the nail bed, genital areas and mouth. Mast cell tumors in the internal organs have a poor prognosis.

Not a great deal is known about this form of cancer – because it does not occur in humans, less research has been undertaken.

As I mentioned the first article – Dog Cancer Facts – there are many, many forms of cancer, and each is a disease in its own right which has it’s own specific treatment and prognosis.

In the next article I’ll give you 10 tips for facing cancer should your dog be diagnosed with a malignant tumor.

Be Sociable, Share!


  1. Just lost a male pyr that was 7 1/2 years old to a brain tumor. He went very fast, had to put him down 10 days after first seizure showed. It ripped my heart out to put him down. He was really my best buddy. It’s been over 3 months and I still have bad moments. Never had a dog as great as he was.

  2. Skip, thanks for your post.
    That’s a heart breaking experience to have to go through; dogs leave such a big paw print on our hearts that I don’t think we ever fully get over their passing.
    I still get misty eyed when I think about my first dog, and she left us over 20 years ago.

  3. i am losing a 5 1/2 year old golden to lymphoma. he was diagnosed only 5 months ago. we hoped chemo would give us a year or two but he is already out of remission. we changed his diet and tried every vitamin and herbal remedy we could find.. it seems unbelievable he will be gone in less than two months

  4. Penny, I am so sorry to hear this – I hope in the next few weeks you will share many precious moments with your dog that you’ll treasure forever. I’m not sure I’d cope very well if I was in your position. Best wishes, Clare.

  5. i just lost my precious “Prince”, 4 weeks ago. We had been best buddies for 12 yrs. I wish i had had the time to find out info regarding spenic tumors. I learned he had a tumor on Monday morning & lost him in surgery on Tuesday. I was alone & trying to understand all medical jargon being thrown at me & make the right decisions while reeling emotionally. I never got to say goodbye. The option to put him to sleep was never brought up by the vet only that he needed surgery asap. Having time now to research this, i would not have agreed to surgery, instead we would’ve gotten burgers & dishes of ice cream & cuddled for the day, then put him to sleep. Don’t be pressured into fast decissions, you will live with them forever. I will always regret mine,as he deserved better. I cry every day & miss him terribly.

  6. 10 months ago, our four year old Doberman was diagnsed with Stage 5 lymphoma.
    A chemo protocol was completed and Lizzie was pronounced in remission. Three days later, a lump appeared that shouldn’t have been cancerous, was treated with antibiotics but failed to respond and biopsy was preformed to discover it was indeed lymphoma agan/still.
    I think that using LDN we will beat our dog’s lymphoma. We have watched that cancerous lump get smaller every week, even every day to now be 10% of the size it was when the biopsy results came in.
    For anybody who is faced with cancer in pet or themselves, please check out http://www.lowdosenaltrexone.com. Five well spent minutes.

  7. Important edit of my post. The LDN site is: http://www.lowdosenaltrexone.org

  8. Hi. I have a Lab (Shandy) who is 8 years old. Over the last 10 days she has developed a lumpy mass on her left shoulder. I took her to the vet and when they put a needle in, they took out some dark blood, like old blood.The area is about 30cm long and 15cm wide. Does this sound like Hemangiosarcoma and what is the prognosis without surgery. She is also anaemic and her blood count was also not normal. Any help or info is appreciated.
    Thanks very much. Trish

  9. Am losing my 2 year old Golden to soft tissue cancer in his throat/neck region. The cancer is intertwined in his throat, artery, etc and cannot be operated on. He is so young and it is heartwrenching to watch him go through this – he doesn’t seem to be in pain yet but his left side of his face is partially paralyzed so it is hard for him to eat/drink normally – he has to be hand fed and the water held for him. If anyone has an experience with this please let me know since I am having a hard time coming to grips with this since he is so young and I spent the last month (and $6000) to get to the point of a diagnosis and now I can’t do anything for him.

  10. Hello

    Just read your article about dog cancers…and some of the responses.

    Our 13 year old part lab has a terrible tumor on her hip that has ruptured. (body tissue hanging out….) The only option is radical surgery but would it be the best for her??
    Her age is against her and that is why we decided to not get her operated on…but it is still creating guilt feelings in me because she stilll is lively, eats well and hasn’t seemed to have been affected by the tumor.
    Hope some one out there has had a similar experience or can help us with our very difficult decision.

  11. Louisa McCleary says:

    I just put down a 14 and 3/4 year old cairn terrier who had a liver tumor that had ruptured. The vet was very clear that he was suffering and that this was the merciful thing to do. He had collapsed with a kind of seizure and was having trouble breathing. I hope I did the right thing. The vet was very clear that I did, but I guess I still wonder if I could have kept him with us a bit longer without undue suffering. Anyone know anything about this?

  12. My 5 year old golden retriever was diagnosed with histiocytic sarcoma. She had surgery in April and received radiation for 22 days. 2 weeks after the end of radiation, we found that cancer has spread to her lungs and lymph node. We decided to forgo chemotherapy since it only extends her life for 1-2 months. As a result, she was given 1-2 months to live. We are now trying the LDN-AP protocol. She is on the LDN therapy for 2 weeks and is doing extremely well. I am now gradually adding the other 2 herbal meds . I am hoping that this protocol might extend her life as well as improve the quality of life.

  13. In 2001 we had a 12 year old beagle mix who had a huge lump on his neck. The Vet took it out and said that our dog had cancer of the connective tissue but that he had gotten all of the cancer out. . We were indeed lucky that it had not spread. The Vet could not believe how well Zeke did considering he was 12. They had orginally intended for Zeke to stay overnight at the Vet, but he was so lively that they called us at 4pm, (he was operated on at 6:30 am), and told us to pick him up. Zeke was pulling at his leash and almost acted as if nothing had happened! He remained cancer-free, and lived to be 15.

  14. I have a 65lb choc lab that is almost eight. He is not fixed, I have not had any problems with him and he behaves very well. One vet told me he runs a very high risk of testicular cancer if I don’t have him fixed. And another told me that if he behaves well and stays in the yard not to worry so much because testicular cancer is very rare in dogs. What do I believe?

  15. Nick- Yes, its true. He runs a higher risk of testicular cancer if he has testicles 🙂 PLEASE spay and neuter your pets. There are enough homeless dogs in this world, please don’t let your un neutered dog add to that.

    My 12 year old Labrador Retriever, Bruce, was just diagnosed with cancer a week ago today. We rescued him from our local humane society because he was so old that nobody paid any attention to him and he was scheduled to be put to sleep hours later. We couldn’t handle that, so we took him home. He is the most sweet, kind, gentle old soul. He is at the stage of cancer where his breathing is difficult (especially at night) and his appetite is lowered dramatically. I’m so very heart broken. I love him dearly and I miss him already. The vet told me to brace myself, because he will become very sick, very quickly. I don’t think he has more than 3 weeks, if that. I’m just so sad. He’s not even gone yet and I miss him terribly :'(
    For those that have lost a beloved pet before, how did you cope? I need some shoulders to cry on about now … If you’re able to, I’m also on Facebook to keep in contact with. You can look me up by my email: Ariel_Fay@Yahoo.com. I need all the support I can get 🙁

  16. Denise Villere says:

    We have a 10 yr old black Lab who was diagnosed with Cancer masses all over which included his lymph nodes.
    We were going to put him down that day, but could not bring ourselves to do it. He still eats and moves around slowly, seems happy. I can’t tell if he is in pain but would imagine with such large masses he has to be.
    Anyway, I am just wondering if anyone would know how long does a dog live after being diagnosed with cancer in the lymph nodes ?
    We also have a female yellow Lab who is around 8 yrs old and she has a huge reddish mass on her belly and started throwing up whole kibbles this week. (hours after eating)
    So confused.

  17. Barbara Phillips says:

    My 10yr old Black lab who has just been diagnosed with Hemangiosarcom, he is having 6 chemo treatments at 3 wky intervals. He had his Spleen removed. The vet said this hopefully would give him a fairly good quality of life for maybe another year. We hope it will be more.

  18. My dog died last night he was a boxer/pit mix 12 /3/4 yrs old would have been 13 end of December. He had a type 2 tumor on his shoulder remove a few months ago they said cancer free. Last week took to the vet he told me he was geat shape for his age let him enjoy his last few years…then this week first not walking so good then not able to walk to he collapse outside , he eyes went back and he died…

  19. My dog just pass away in this early morning. I was not at home for yesterday till just now, I rushed back to bury her. She was an old dog who companied me for 10 years. Half year ago, she has Transmissible Venereal Tumor (TvT) on her sexual organ. But, she has recovered after 4 times of injection by kimo. She recover very fast as veterinarian has said that this type of cancerous tumor is 100% curable.
    After she recover, she looks very healthy and she was on weight. She was getting fatter and fatter. At first, I am quite worried that something happen to her, but she seem like very healthy and happy and normal as she was a fat dog in these years. Last week, I came back my hometown and noticed that she really fat and seem like pregnant. How could it be? 10 years dog still pregnant? However, I believed she was pregnant and this was her 2nd time to be mother in her life. I am happy too. Yesterday night, she did not want to eat and look like she was ill. And this early morning, my family noticed that she passed away in peacefully. She slept on the place as usual. Her mouth is closed. Her body is just like a balloon. Even though it was 8 hours after she passed away, her stomach still very soft and I can feel something wrong inside her stomach or body. There are not puppies! I am sad like hell. I lost my Shimmi forever. I love her!

  20. I have a 10 year old female lab who has cancer. She collapsed a few days after Thanksgiving due to a large tumor on her spleen. We had no indication of any problems prior to her collapse. We have an amazing vet and he removed her spleen and tumor. Days later we got the terrible news that it was malignant. After all the research I have done, I realized that I may have been able to save my dog. Please look into putting your loved ones on a raw diet. Organic meat is the best. With a raw diet there are no fillers. It’s just real food which can be absorbed and all the nutrients used. Shame on the people who only see dollar signs in the pet industry and think it’s ok to cut corners. I fed my dog a high end kibble for nine years. Never again.

  21. Check out http://www.lowdosenaltrexone.org With LDN no significant side effects – an effective immune system booster which has caused very significant improvement in many cancers. Watched tumor in a dog shrink from 18 cubic inches to zero. It saved me from operation.

  22. I have a female Border Collie who is 12. I was never told she would get cancer if she was not fixed. I took her to the vet last year for a lump on her chest, the vet said it was a fatty tumor no need to worry. The tumor started to grow but I kept thinking the vet was right with his diagnosis. I finally took her back to vet and of course she needed surgery. The vet removed the large lump and several mammary glands. It has been 3 weeks since her surgery and she seems not to be in pain, playing, running, jumping, eats and drinks begs for people food:) the vet says if she gets another growth to bring her in right away and he will remove it. I was lucky that the ASPCA in our town donated $200.00 towards her surgery. I don’t know how long Princess will survive but I cherish every day with her.

  23. I was told by my vet not to remove my beagles mammory tumor because she was too old. I think she is around 11. I think it was a mistake, because the tumor grew, and she never got sic, now her entire lymph on the side of the tumor suddenly swelled up and she is in gret pain with a huge swollen lymph. If I had told vet to do full masectomy and lymph take out 6 months ago, I know it would have made her life much easier. sometimes it is ok to help an old dog to go a few more years. This way she is dying is painful, i think it would have been ok if we took it all off when it first appeared instead of just sayin- well, shes older now, so just let her go! no! it wasnt the right decision and I do wish my vet had advised me the other way. Its ok to do surgery if the dog is older, they can make good come backs

  24. Vivian Gerk says:

    My rat terrier, Baby, has had the mast cells for 3 years. The vet gave her six months 3 years ago. The tumor is the size of a
    base ball, but it doesn’t seem to bother her. She runs around, eats dog food and table scraps, plays with the new kitty, and sleeps in a queen size bed. I think she is spoiled and doesn’t want to leave.
    She is 15 now, and even though she looks like quasimodo, she continues to enjoy her life. And I enjoy having her!

  25. Old 15 year old golden retreiver was diagnosed with sarcoma located under the skin on her side. We had the tumor removed surgically six months ago. She had another growth near her tail which was removed one month ago that was not canerous. However, at that time the vet palpated a large tumor on her speen the size of a baseball. We are now debating whether it makes sense to have her operated on, given her age and the prospect that she might die or be significantly impaired during recovery from the surgery. The vet said she could not do a biopsy to determine if the gorwth is cancer until the surgery is done to avoid furher complications from the growth. Any advice would be appreciated.

  26. I have a 7 year old golden, Sinbad. I am waiting to find out if my baby boy has cancer .The vet found a mass on his liver, and theres a whitish haze in the xrays of his lungs which do not look good either The vet took a biopsy of the mass on his liver, so I should know tomorrow. He has lost weight and is breathing very shallow….I am hoping that this is Valley fever since we were living in the central valley in California and we were right next to a new construction site, so the dirt was being turned over. I had no idea that dogs could get valley fever, at least that can be treated. I am so worried and my heart aches. please say a prayer for him.

Speak Your Mind