Tumors in Dogs – Most Common Canine Tumors

Dog Tumor

Tumors in dogs are serious health conditions that can threaten the life of your four-legged friend. They generally occur among older dogs, and if they are not treated accordingly, the situation can get out of control pretty fast. The best prevention, in this case, is to know how to identify the early signs. This is why it is a good idea to learn more about the types of tumors and where they can occur.

There are various signs that can indicate that something is wrong with your dog. Whether it is a swelling that gets bigger and bigger, or you can see a new mass on its body, you need to go the veterinary in order to receive treatment. The sooner the problem is spotted, the higher the chances are to avoid complications.


When a tumor occurs, the best solution is surgery. Though this sounds scary, it is mandatory to remove it in order to prevent it from spreading through the body. If it was not spotted on time, there are other additional treatments necessary, like radiation therapy, or even chemotherapy. Besides the fact that they are very powerful, they can also be pretty expensive. This is why it is better to know how to spot such a health problem.

If the dog receives the right treatment from the initial stage, it may even skip surgery. You can find out more about dog tumors and how they can affect the life of your pet in the following paragraphs.

Types of Tumors

You can only help your dog if you know how to spot a potential tumor. This means that it is mandatory to be aware of the major types and which are the clinical signs. At the same time, the more you know about how they evolve, the better you can support your pet throughout the process.

It is also important to be aware of the breeds that are predisposed to this health problem and which is the most appropriate treatment. Check out our post on the healthiest dog breeds.

The table presented below aims to introduce you to this matter, while the following paragraphs will treat each of the 10 types of tumors in a detailed manner.

LYMPHOMA any age Golden Retriever Single or multi-drug chemotherapy
HEMANGIOSARCOMA middle aged and old dogs Golden RetrieverGerman Shepherds Surgery and chemotherapy
OSTEOSARCOMA middle aged and old dogs Great Danes Surgery and chemotherapy
MAST CELL TUMOR any age BoxersBulldogs AntihistaminesRemove the area of skin around the tumor
MELANOMA any age Scottish TerrierDoberman Pinscher Surgery, radiation and chemotherapy
SQUAMOUS CELL CARCINOMA middle aged and old dogs KeeshondStandard Schnauzer

Basset Hound


MAMMARY CARCINOMA females that were not spayed, or were sprayed after the age of 2 PoodlesDachshunds


Surgery and chemotherapy
APOCRINE GLAND CARCINOMA middle aged and old dogs Golden RetrieverCollies

German Shepherds

Old English Sheepdogs

Cocker Spaniel

Surgery and radiation
TRANSITIONAL CELL CARCINOMA any age Shetland SheepdogWest Highland White Terrier


Scottish Terrier

Chemotherapy and anti-inflammatory drugs
SOFT TISSUE SARCOMA any age Labrador RetrieverGolden Retriever Surgery, radiation and chemotherapy

1. Lymphoma

Lymphoma is a type of tumor that appears frequently in the canine world. It can strike any time, thus it is mandatory to be aware of the signs that can indicate such a disease. According to the place it appears, there are two variations:

  • Peripheral Lymphoma — the most visible signs are the swollen lymph nodes situated right under the jaw, behind the knees or in the shoulder area. Though there are no other major signs that indicate such an illness, your dog may feel lethargic and will start eating less food.
  • Internal Lymphoma — this type of tumor is more aggressive than the previous one because it affects organs like liver and spleen. As a result, the symptoms are more severe and include vomiting, difficulty in breathing, diarrhea and abdominal pain. It also advances incredibly fast and a dog that does not receive treatment will surely die in less than a month.

2. Hemangiosarcoma

Hemangiosarcoma is a type of tumor that requires a lot of time to develop. It is not painful, and it affects the cells that line the blood vessels. Unfortunately, in this case, there are no visible signs until the situation is really serious.

The dog will start feeling bad only when the tumor gets ruptured and causes internal bleeding. The organs that are usually affected are the spleen, liver, heart and skin. In order to be able to do something for your pet it is important to watch out for signs like pale gums, weakness and difficulty in breathing.

They generally indicate an internal bleeding, thus immediate treatment is required. This type of tumor is almost impossible to identify before it is at an advanced level. The solution, at this stage, is surgery because it is the only way to stop the bleeding. If the spleen is the organ affected it will be completely removed.

After two weeks, the dog will need to take several chemotherapy sessions. However, though the treatment is aggressive, there are only few pets who manage to survive this terrible disease. In most cases, the survival time varies between 2 to 3 months with surgery alone and 5 to 7 months if it takes chemotherapy sessions.

3. Osteosarcoma

Osteosarcoma is a bone tumor that is highly spread among dogs. It is very aggressive because it can spread really fast into other organs. As a result, the chances of survival are really low, especially if it is not diagnosed quickly.

The signs are hard to identify because they are very subtle. They can even be joint pain, swelling and bone aches. When the pain gets more intense, the dog refuses food and feels tired all the time. Unfortunately, most pet owners realize that something is wrong only when a mass growth is visible on the body. As the treatment is severe, there are various side effects and in most cases it leads to death.

4. Mast Cell Tumor

Mast cells can be found in the vessels that are close to external surfaces, like the mouth, lungs, skin, or nose. Their main functions are to protect the organism against parasitic infestation and to repair the tissue. They also play a role in allergies as they modify inflammation and immune reactions. They derive from the bone marrow, so they are spread throughout the body.

There are various types of mast cell tumors with different impact on the dog’s organism. The stages are from 1 to 3, the last one being the most predisposed to metastasis. As this is a disease that can be treated especially if it is diagnosed at an early stage, it is mandatory to be able to recognize the symptoms.

Mast Cell Tumor

In this case, the symptoms depend on the grade of the tumor, but also on where it is located. If they are at the skin level, you can notice redness or fluid build-ups that can be itchy. They tend to evolve pretty fast, so if you notice something that does not look like an injury it is highly advisable to go straight to the veterinarian.

It is also good to know that half of these tumors appear at the trunk level, while 40 percent on the legs and tail and only 10 percent at the neck and head level. Though it is yet unknown what causes this illness, it is important to receive treatment fast in order to prevent it to spread throughout the body.

5. Melanoma

Melanoma is another common tumor in the animal kingdom. As a result, it is mandatory to be able to differentiate the signs that indicate such an illness. However, the good news is that it can be treated successfully if it is diagnosed at an early stage. An important aspect concerning this tumor is the fact that there are two types with different degrees of risks:

  • Benign melanomas — they can be spotted on the head and back area. They have a round shape and are darkly pigmented.
  • Malignant melanomas — they are node swellings that do not have the typical dark pigment.

If you see such swelling on your dog, you need to go to the veterinarian immediately. As there are two types, a definitive diagnosis can be given after analyzing a small section of the swelling. The biopsy can provide an accurate answer and lead to the adequate treatment. In order to remove the melanoma it is required a surgical excision.

If the tumor is malignant, there are high chances to spread to other organs. In order to prevent this from happening, it is important to take some chemotherapy sessions. If the tumor is benign, the surgery is not necessary, but you must have it checked on a regular basis in order to prevent it to become malignant.

6. Squamous Cell Carcinoma

Squamous cell carcinoma is a tumor that appears at the epidermal level. It is relatively rare in dogs, and though it evolves pretty slow, it is incredibly aggressive. It usually appears on the pigmented area of skin, where the hair coat is very sparse.

Dogs that spend most of their lives outside are predisposed to this disease much more than the ones that are kept indoors. The main factor is the direct exposure to ultraviolet radiation. As dogs are covered with hair, it is more difficult to check if there are any damages or burns caused by the sun.

In order to avoid this tumor to become aggressive it is a good idea to check the condition of your dog’s skin regularly, especially during summer months. If you notice any signs of ulcerated nodules or plaques, it is time to go to the veterinarian as soon as possible.

The areas that need to be carefully analyzed are the abdomen and inguinal skin. They are the most sensitive, and as they are not covered with hair, they are directly exposed to the sun. You can prevent this terrible disease by assuring a shady place for your dog to rest and constant access to fresh water. Avoid taking it for a walk when it is too hot outside, and if possible keep it indoors in the afternoon.

7. Mammary Carcinoma

Mammary carcinoma is a health problem that affects female dogs. This tumor can either be benign or malignant. As a result, a biopsy is required in order to determine the gravity of the situation. It is not difficult to observe this illness because it can be spotted with the naked eye. If you see swellings or solid mass in the mammary area, it is necessary to ask for professional guidance. It is also advisable to palpate the area and see whether it feels like a piece of pea.

As they are hard, they can be moved with the hand. This is the first stage of the illness, and it can evolve pretty fast. In less than a month, they can actually double the size, thus the visit to the vet must not be postponed.

Mammary carcinoma is often accompanied by ulceration, bleeding and has an irregular shape. In order to determine whether it is malignant or benign it is necessary to do a biopsy. If the form is very aggressive, it can lead to metastasize that end up affecting the lungs.

The best solution to protect your dog from this terrible disease is spaying. If it is done at an early age, it is even better. Though  there are situations when the tumor appears even after this procedure, it is the only way you can actually improve the health condition of your pet.

8. Apocrine Gland Carcinoma

Apocrine gland carcinoma is a type of tumor that is non-malignant in about 70% of cases. There are several forms and they differ in intensity, thus it is important to keep it under control from an early stage. It can be located either in the glands or in the ducts. The mild variant is represented by sub-cutis nodules, while the aggressive one by ulcerative plaque.

It is important to go to the veterinarian as soon as you spot any of the two signs in order to get your dog checked. As it appears to be similar to an injury caused by licking, some pets are diagnosed only when it is too late, and the illness is in an advanced stage.

In order to determine the evolution of the tumor it is important to start with a biopsy. Once the veterinarian receives the results it is easier to establish a correct diagnosis and decide what can be done next. In most cases, the treatment recommended is surgical intervention. There are cases when surgery is not sufficient, and the dog must also follow a radiation therapy session.

The good news is that this illness responds very well to the treatment, thus the pet has high chances to recover completely. However, just like in the case of all types of tumors, it is mandatory to discover it at an early stage in order to prevent further damage.

9. Transitional Cell Carcinoma

Transitional cell carcinoma affects the urinary and reproductive systems. This means that it affects the kidneys, urethras, prostate and vagina.  It is believed that certain flea-control products that are based on carbamate and organophosphates can lead to this terrible disease. There are various symptoms that can indicate the presence of this tumor.

The most common one is the staining to urinate. There are also cases when the dog urinates frequently, but only small amounts. If accidents like wetting the floor or the bed happen frequently, it can also be a sign that the urinary system does not work properly. However, if the dog urinates with difficulty, or you see blood, you need to go to the veterinarian immediately.


In order to establish a correct diagnosis it is important to analyze the symptoms, thus you need to think about how the dog reacted in the past weeks. The next step is to take some blood and urinal samples. They will indicate whether it is a urinary tract infection or something more serious.

X-rays will be used to locate the tumor and see whether it spread to other organs. In order o determine its nature it is important to perform a biopsy. According to the results, the veterinarian can prescribe the adequate treatment.

10. Soft Tissue Sarcoma

Soft tissue sarcoma is a tumor that affects the blood vessels. Fortunately, this is an illness that does not affect many dogs. It can be either malignant or benign. Though the tumor can be surgically extirpated there are high chances to recur. At the same time, if the diameter exceeds 5 centimeters, it cannot be eliminated with radiation or chemotherapy. It is also important to know that this is not an aggressive disease, and it is quite hard to diagnose. When it comes to the predisposition, usually males are more affected by it than females.

HemangiosarcomaWith all this said, one kind of tumor you shouldn’t worry much about is lipoma; to learn more, you should definitely check out this article on lipoma in dogs.

It can be concluded that the best way to keep your pet safe is to be able to identify the first signs that can indicate an illness. Furthermore, all pet owners must understand the importance of healthy food and how an un-balanced diet and lack of exercise can lead to serious health problems.

Some tumors tend to be more aggressive than others, so you need to be prepared to support your four-legged friend during the entire process. Though surgery is the optimal solution in almost all cases, if the tumor is malignant, additional chemotherapy or radiation is needed.