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Different Types of Tumors in Dogs

María Besteiros
By María Besteiros, Expert veterinary assistant and canine/feline hairdresser.. Updated: January 30, 2024
Different Types of Tumors in Dogs

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The development of tumors in dogs is not a new phenomenon, but our understanding of their causes and treatment is relatively recent. This is partly due to advancements in veterinary medicine, since our ability to treat other canine health issues and use better preventive medicine means they have a greater life expectancy. The longer a dog lives, the more likely they are to develop a tumor. It is also because we are generally more inclined as guardians to spend money on treating tumors which were previously often left to develop without intervention.

It is for this reason, we not only know more about the different types of tumors in dogs, but we have a greater understanding of their causes, symptoms and treatment. AnimalWised explains the most common canine tumors and what you can expect if your dog is diagnosed with one of them.

You may also be interested in: Transmissible Venereal Tumors in Dogs


  1. What are tumors in dogs?
  2. Types of skin tumors in dogs
  3. Types of soft tissue sarcomas in dogs
  4. Types of bone tumors in dogs
  5. Types of reproductive tumors in dogs
  6. Leukemia in dogs
  7. Symptoms of tumors in dogs
  8. Treatment of tumors in dogs
  9. Home remedies to dissolve tumors in dogs
  10. Most common causes of cancer in dogs
See more >>

What are tumors in dogs?

Before we take a look at the different types of dog tumors in more detail, we should make an important distinction about tumors in general. Neoplasms are the abnormal buildup of cells which result in tissue growth. The result is various types of tumors, some of which are benign and others malignant. Malignant tumors are cancers which can metastasize to other parts of the body.

We can also make a general distinction between tumors which appear on the skin and those which develop internally. Skin tumors can often be felt or even seen as they develop, whereas internal tumors are more difficult to observe. Since even cancerous tumors can be asymptomatic during their beginning stages, this makes detection and intervention more difficult.

We may only discover certain tumors when they affect other internal processes of the dog. For example, the dog may experience pain when we touch them somewhere affected by the tumor or they may lose significant weight. Other symptoms may be even more generalized, such as the dog having diarrhea and vomiting at the same time.

Tumors are more likely to develop in middle-aged and older dogs. Their immune defenses are weaker and they are more prone to various ailments. For this reason, we recommend dogs over seven years of age have at least one veterinary checkup per year.

Types of skin tumors in dogs

As we have stated above, there is a diagnostic difference between skin tumors and internal tumors. With skin tumors, we are more likely to see their development because we can more easily visualize and touch them. Some of the most common skin tumors in dogs are:

Papillomas in dogs

They are benign wart-like tumors caused by the canine oral papillomavirus. They are more common in older dogs. Although we can remove warts on dogs, it is always important to have them diagnosed by a veterinarian as we may mistake them for another type of tumor.

Lipomas in dogs

These benign tumors are made up of fat cells, one reason they are more common in overweight dogs. The appearance of lipoma in dogs is rounded and soft to the touch due to the adipose tissue's spongy texture. Lipomas grow slowly and can reach considerable dimensions. There is a malignant variant called liposarcoma.

Histiocytomas in dogs

These tumors are fast growing and can appear in young animals between 1-3 years old. They are observed as small hairless bumps on the dog's skin, with an appearance similar to buttons. Most disappear in a short time without intervention.

Mast cell tumors in dogs

Also known as mastocytes, mast cells are immune system cells which play a role in protecting against allergies and other pathogens. Mast cell tumors are more common in brachycephalic breeds such as boxers and bulldogs. They appear in older dogs and approximately half are malignant. They usually present as red, hairless, multinodular growths. They are capable of releasing substances that cause gastroduodenal ulcers.

Squamous cell carcinomas in dogs

Canine squamous cell carcinomas are related to exposure to ultraviolet radiation and occur in areas of the body with less pigmentation such as the abdomen, nose or lips. Dogs with less pigmentation such as white dog breeds and albino dogs are more prone to this issue and require greater protection against the sun.

Melanomas in dogs

They appear in melanin-producing cells. They are dark nodules that are located in areas such as the eyelids or the mouth, where they are usually malignant.

Different Types of Tumors in Dogs - Types of skin tumors in dogs

Types of soft tissue sarcomas in dogs

These tumors in dogs are malignant and have different origins. There are breeds predisposed to suffer from them such as the German Shepherd, the Boxer and the Golden Retriever. They appear both on the skin and in the organs, and we highlight the following as the most common:

  • Hemangiosarcoma: affects cells in the lining of blood vessels.

  • Osteosarcoma: it is a type of bone tumor in dogs that we will discuss in more detail in the next section.

  • Lymphoma or lymphosarcoma: appears in lymph nodes and organs with lymphoid tissue such as the spleen or bone marrow. It mainly affects middle-aged and older dogs. In addition to symptoms such as apathy, anorexia or weight loss, we will find enlarged lymph nodes. We often notice them when petting and we feel a lump on the dog's neck. Other clinical signs depend on its location.

Types of bone tumors in dogs

They can be both malignant and benign. We have already mentioned osteosarcoma, which fall into the former category of malignant tumors. Although they can appear at any age, there is a greater predisposition among older dogs. These types of tumors in dogs occur most frequently on the front legs, but can also affect the hind legs, ribs or jaw. Symptoms include limping and swelling of the dog's paws, depending on location. They usually spread to the lungs.

Benign bones tumors in dogs include osteomas which develop most commonly on the head and face. Osteochondromas appear in the ribs, vertebrase and extremities, among other places. They can affect younger dogs, so we need to be observant at any stage of their lives.

Types of reproductive tumors in dogs

The reproductive systems of male and female dogs are the source of a wide variety of tumors and cancers. Their removal by neutering and spaying, respectively, prevents the development of these tumors. This is one of the important reasons for spaying and neutering your dog, although there are many others. It is also why neutered dogs generally have a longer life expectancy.

Testicular tumors in dogs

These types of cancer in dogs are more common in older males. They mainly occur in dogs with undescended testicles (cryptorchidism), an issue which should be checked by the veterinarian around the time they reach sexual maturity. Castration before sexual maturity is recommended as prevention and treatment.

Transmissible venereal tumors in dogs

This tumor is rare, but it is contagious through sexual contact between dogs. Transmissible venereal tumors in dogs can also be transmitted through bites, licks or scratches. Tumors being transmitted through direct contact are rare in any animal species. They are cauliflower in shape and can be seen on the face, mouth, nose, and other areas in addition to the sex organs. Although they are not considered very virulent, they can reproduce by metastasis.

Vaginal tumors in female dogs

They appear in older and sexually intact females. They present staining when they sit down, frequent urination and a mass can be seen exiting out through the vulva. We are often first alerted to the problem when we see the dog frequently licking her private area. It is essential to go to the vet to diagnose and treat it.

Ovarian tumors in female dogs

They are usually infrequent and are almost always asymptomatic. There is a malignant variety that can be associated with ascites because it spreads through the abdominal cavity.

Mammary tumors in female dogs

These tumors are very common, especially after six years of age. This is why sterilization is recommended. It is common for them to affect more than one breast and are detected by palpation. Metastasis usually occurs in the lungs, seriously worsening the situation. For this reason, you should see a specialist if you notice your dog has swollen breasts for any reason.

Different Types of Tumors in Dogs - Types of reproductive tumors in dogs

Leukemia in dogs

This cancer affects the blood components in the bone marrow, especially in middle-aged dogs. It produces non-specific symptoms such as fever, anorexia, weight loss or anemia.

Both in this case and in the other types of tumors in dogs, tests such as blood analysis, ultrasound, X-rays or computed tomography will be carried out for diagnosis. Biopsy can confirm the diagnosis and help guide the resultant treatment of canine leukemia.

Symptoms of tumors in dogs

Throughout the article we have mentioned the symptoms of tumors in dogs depending on the type of neoplasm which has developed. Although there are many different reasons for various types of lumps in dogs, we can generally distinguish malignant tumors as those which produce the following symptoms:

  • Lumps or bumps on or under the skin
  • General discomfort
  • Loss of weight and appetite
  • Lethargy
  • Tiredness
  • Signs of pain such as whining when palpating an area
  • Coat in poor condition or hair loss
  • Bleeding wounds like ulcers
  • Appearance of secondary infections due to the weakness of the immune system
  • Vomiting and/or diarrhea with or without the presence of blood

Most of the above symptoms are generalized, meaning they are typical of multiple health problems. This is one reason it can take a long time to detect cancer. It is essential to go to routine veterinary visits, since this is where the specialist can promptly detect any anomaly. In the next section we will see the treatment options for various tumors in dogs.

Different Types of Tumors in Dogs - Symptoms of tumors in dogs

Treatment of tumors in dogs

Currently, there are different treatments available to eliminate certain tumors in dogs. It is important to know that many benign and malignant tumors can be treated, especially with early intervention. Unfortunately, not all cancers can be cured. Even some benign tumors may be in positions which make excision too difficult, so they may remain untreated. The best results are obtained by prompt diagnosis and a personalized treatment .

The following are common treatments for cancerous tumors in dogs:

  • Surgery: the tumor and surrounding tissue are removed to prevent recurrences.
  • Radiotherapy: this is a process of irradiating the tumor which requires specific technical equipment to do so effectively. The radiation blasts the cancer cells and destroys them, but there is a risk of also damaging healthy cells.
  • Chemotherapy: aimed at controlling metastases, it usually requires a combination with another treatment to obtain good results. The drugs used in chemotherapy for dogs have side effects which need to be taken into account when assessing the viability of the treatment.
  • Immunotherapy: this is a treatment option which is still under development, but its basic function is to stimulate the immune system into rejecting the cancer.

As we said, it is important to highlight that not all tumors in dogs can be cured, especially those that metastasize. For this reason, it is crucial to go to the vet in case of any symptoms, since an early stage detection can be the difference between eliminating the cancer or the death of the dog.

Home remedies to dissolve tumors in dogs

Unfortunately, there are NO home remedies to cure cancer in dogs. Although various sources tout herbal remedies or traditional medicine techniques which have cancer eliminating properties, the best chance your dog has of survival is to speak to a veterinary specialist. They can diagnose the type of tumor in the dog and recommend the most efective treatment.

This does not mean invasive treatments are the only course of action. We will still need to ensure the dog has a quality diet to strengthen their immune system. We will need to amend their exercise regimens according to their needs during the period of treatment. We also need to ensure we provide plenty of love and emotional support since the dog will be undergoing a process which can be physically painful and emotionally distressing.

Relaxation exercises that keep the dog calm can be very beneficial. Massaging the dog not only helps to relieve stress, but it helps to provide security since they know their guardian is there for them.

Different Types of Tumors in Dogs - Home remedies to dissolve tumors in dogs

Most common causes of cancer in dogs

Most cells in the body reproduce throughout the individual's life. This duplication originates identical cells that will continue to perform the same function. This process is controlled by genes and any alteration in them results in cells that replicate at high speed and form masses that end up displacing healthy cells. This is how tumors are generated in dogs.

The alterations responsible for these mutations are multiple, since the genes can be activated or deactivated by factors such as diet, stress or the environment. In human medicine some carcinogens have been identified that will increase the risk of cancer. For example, ultraviolet rays are associated with skin cancer, X-rays with thyroid cancer, tobacco with lung cancer, some viruses with sarcoma, etc.

In dogs we know that the appearance of mammary tumors is related to the hormones of the sexual cycle, hence early sterilization has a preventive effect. However, we can influence the development of these tumors if we introduce more carcinogens to their lives. For example, some guardians may smoke around their dog and increase the risk of lun cancers. They may also leave the dog outside without shelter, exposing them to harmful UV rays.

This article is purely informative. AnimalWised does not have the authority to prescribe any veterinary treatment or create a diagnosis. We invite you to take your pet to the veterinarian if they are suffering from any condition or pain.

If you want to read similar articles to Different Types of Tumors in Dogs, we recommend you visit our Other health problems category.

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Different Types of Tumors in Dogs