Dog Tumors, Growths, and Cysts

Healthy puppy after medical exam

On all breeds of dogs, lumps and bumps are typical. Dogs can develop growths, tumors, cysts, and masses at any age, although older dogs are more likely to develop them. Knowing the various growths you could run into is useful if you own a dog. Any growth or tumor that persists or seems strange should be called your veterinarian right away.

What Are Tumors, Growths, and Cysts?

Any unexplained bulge or bump will often be referred to as a growth, mass, or tumor by vets. Although the terminology may often be used interchangeably, most veterinarians refrain from using the word tumor unless a specific kind of malignancy has been identified in the mass.

Symptoms of Tumors, Growths, and Cysts in Dogs

Abnormal growths can occur anywhere on the body or in the mouth. Warning signs include:


  • An abnormal skin lump or a bump ranging in size from very small to very large
  • A swollen area (particularly within the body)
  • An oral growth
  • Enlarged lymph nodes
  • Lameness or swelling affecting a bone

Abnormal Lump or Bump

  • Sebaceous cysts, adenomas, and adenocarcinomas are common types of skin cysts that contain sebum, a thick, oily material normally found in the skin around the hair follicles. These masses may be found anywhere on the body. Sebaceous cysts are benign but can also be mistaken for a malignant tumor called a sebaceous gland adenocarcinoma or a benign mass called a sebaceous gland adenoma. If the cyst does not bother your dog, your vet might leave it alone, but a cyst can be surgically removed if necessary. Once removed, the cyst should be sent to a lab so a veterinary pathologist can determine that it is, indeed, just a sebaceous cyst or an adenoma or adenocarcinoma that may require more treatment.
  • Histiocytomas are red bumps that can appear quickly on your dog's skin and tend to go away on their own over the course of a few months. Although they are benign tumors, some can grow rapidly and really bother your dog. Your vet may recommend the removal of large or irritated histiocytomas. Unlike other common skin masses, histiocytomas are most frequently diagnosed in younger dogs.
  • Skin tags on dogs are similar to those humans get. Some can get quite large and pendulous, hanging off the skin by a narrow stalk. Skin tags are benign and are usually not removed unless they bother the dog or get very large and irritated.
  • Malignant melanoma can occur on the skin and/or in the mouth and is thought to be caused by sun exposure. Many of these tumors have a black color but not all will look the same.
  • Squamous cell carcinoma is a type of tumor that may be caused by sun exposure. This type of cancer can occur on the skin and/or in the mouth. These tumors can have a pink or reddish color and misshapen, "raw" appearance.
  • Mast cell tumors may occur as skin bumps or internal tumors. These masses may release histamine when disturbed, which can have a negative effect on your dog's body. If your vet suspects a mast cell tumor, your dog may be treated first with diphenhydramine to minimize the histamine release. Once the mass is removed, a pathologist will grade the tumor as I, II, or II. This grading indicates how malignant the tumor is and how likely it is to metastasize (spread to other parts of your dog's body).

Swollen Area in the Body

  • Internal masses develop within the chest or abdomen, especially in some senior dogs. Internal masses may be found due to the symptoms they create (difficulty breathing or vomiting, for example) or during a routine physical examination. Internal masses may be benign or malignant and are usually definitively diagnosed through a combination of radiographs, ultrasound, lab work, and biopsy. Treatment depends on the location and type of tumor.
  • Mammary tumors are more common in female dogs, particularly in those that are but can sometimes occur in as well. Though some mammary masses may be benign, many are cancerous. Prognosis improves when the masses are diagnosed and surgically removed when they are small.
  • Lipomas are common types of tumors seen in dogs. A lipoma is a benign fatty mass that can be found anywhere on a dog's body, typically under the skin. They usually feel soft and moveable and rarely cause pain or discomfort for the dog. Lipomas can be surgically removed if they interfere with your dog's mobility or comfort, grow rapidly, or rupture (causing skin damage). In rare cases, an apparent lipoma is actually a malignant tumor called liposarcoma. Diagnostic testing can differentiate the two.

What Is a Lipoma?

A lipoma is a fatty tumor just below the skin. It is a benign (non-cancerous) lump made up from fatty tissue.

An Oral Growth

The mouth of your dog may develop any number of different growths. Even though certain growths are difficult to notice, they can nevertheless produce symptoms including foul breath, difficulty chewing, problems keeping objects in the mouth, oral discomfort, and pawing at the face or mouth. These symptoms should not be disregarded because they may potentially be markers of oral disease.

  • Papillomas are warts caused by the papillomavirus. They can appear on the dog's lips, face, and inside the mouth. Papillomas are benign but very contagious. They can be removed if they cause problems for your dog, but in many cases, they will resolve on their own.
  • An epulis is an oral growth that usually forms on the gum tissue around a tooth. Many epulides are benign, but some can be malignant, so further diagnostics are necessary.
  • Gingival hyperplasia is a benign overgrowth of gum tissue that may look a little bit like a tumor in some dogs. This excess gum tissue can be removed if it's affecting the teeth or is bothersome to the dog. The removed tissue may be sent to a veterinary pathologist just to make sure there are no cancer cells present.
  • Oral melanoma can occur in the mouth and may be black in color.
  • Squamous cell carcinoma and fibrosarcoma are other common types of cancer that can develop within the mouth of dogs.

Some oral tumors can harm the jawbone, teeth, and other facial bones. Your veterinarian will probably advise giving your dog anesthetic in order to perform a complete examination and radiographs if they discover an oral tumor in your dog.

Enlarged Lymph Nodes

Lymphoma is a malignancy of certain immune system cells and is not a tumor in the traditional sense. However, an expansion of the lymph nodes, which can seem and feel like tumors, is frequently the first indication of canine lymphoma.

Pet owners typically see lumps in the neck region, but they can also appear in the armpits, lower belly (around the thighs), and the back of the knees. An aspiration or biopsy with a tiny needle is frequently used to diagnose lymphoma. The most popular kind of treatment for lymphoma is chemotherapy.

Lameness or Swelling Affecting a Bone

It might be a bulging growth affecting a bone that you can't feel if you observe that your dog is walking awkwardly, favoring one leg over the other, or acting in any other way lame. If your dog has a tumor, growth, or cyst, the region is probably uncomfortable and painful, necessitating a trip to the doctor for a diagnosis.

Causes of Tumors, Growths, and Cysts

Similar to humans, it can be challenging to identify the precise reason for an animal's tumor, growth, or cyst. Dogs' skin issues, however, may be brought on by the environment or a disease. Other kinds of cancers, growths, and cysts can also be significantly influenced by genetics.

Diagnosing Tumors, Growth, and Cysts in Dogs

Your veterinarian will do a physical examination once a lump is found. The veterinarian may advise a time of observation if the lump is relatively recent and perhaps transient (such as the consequence of an injection or bug bite), but in most circumstances, they will run further diagnostics to identify the kind of cells that make up the mass. In most cases, this entails taking a sample of the substance from the bulk and examining it under a microscope.

These samples are normally taken by a veterinarian by a biopsy or fine needle aspiration. If the lump is malignant, analysis of the samples (typically carried out by a pathologist) can reveal what kind of cancer is present and if it is.

If your veterinarian diagnoses your dog with cancer, additional diagnostics will most likely be recommended, including:

  • Lab tests such as blood chemistry, complete blood count, and urinalysis
  • Radiographs (X-rays) that can reveal signs of metastasis or other problems
  • Ultrasound, which can offer a better view of internal organs and look for metastasis
  • CT scan or MRI, which will help vets get a closer look at the structure of your dog's tumor and some internal organs.

Some advanced diagnostics and treatments must be performed by a veterinary specialist.


The next suggestion is often a biopsy if a tiny needle aspirate is ineffective (or if your veterinarian feels it's not the best course of action). Depending on the size and location of the tumor, local anaesthetic may be utilized instead of general anesthesia or sedation during the biopsy procedure.

A special, big needle may be used to do the biopsy. Or, the veterinarian could operate to cut through the tumor. In rare circumstances, the whole lump is surgically removed and submitted to a lab for analysis.

Prognosis for Dogs with Tumors, Growths, and Cysts

The prognosis is frequently favorable if you and your veterinarian are proactive in treating the tumor, growth, or cyst in your dog. The easier it will be to aspirate or remove a tumor, growth, or cyst, the smaller it is, and frequently no extra therapies are required.

How to Prevent Tumors, Growths, and Cysts

Many lumps, bumps, and growths cannot be prevented, but some can. For example, spaying your dog before her first heat cycle virtually eliminates the chances that she will develop mammary tumors.

Maintaining a nutritious food and an active lifestyle for your dog is always advised. You should also take your dog to the doctor at least once a year for preventative treatment. Maintain a regular grooming routine and pay attention to any lumps or bumps that have recently appeared. Tracking growth with a photo and a written record is helpful, and if you see a sudden shift, consult a veterinarian straight once.

If you suspect your pet is sick, call your vet immediately. For health-related questions, always consult your veterinarian, as they have examined your pet, know the pet's health history, and can make the best recommendations for your pet.


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