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Skin Growths on Dogs – Types, Causes, Diagnosis, Prevention & Treatments

↯ Key takeaway points

  • Skin growths on dogs can vary in shape and complexity, and proper diagnosis is needed to determine the nature of the growth.
  • There are different types of skin growths, including cysts, skin tags, histiocytomas, squamous cell carcinoma, malignant melanoma, and mammary tumors.
  • Causes of skin growths can include genetics, heredity, lifestyle, hygiene, and exposure to chemicals and pollutants.
  • Signs of skin growths include small and large lumps, red itchy lumps, swollen areas, enlarged lymph nodes, and pain.
  • Treatments for skin growths include surgery, chemotherapy, radiation, and experimental treatments like modified Mohs paste and immunogene therapy. Holistic alternatives like changes in diet and supplements can also be used to support the main treatment.
Breeding Business is passionate about all sorts of domesticated pets. They have written dozens of articles across the web.
Zoo and wildlife doctor in veterinary medicine passionate about animal welfare and preventive medicine.
Published on
Friday 9 August 2019
Last updated on
Thursday 22 June 2023
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Skin growths on dogs can come in different shapes, and therefore, they are a very complex matter. However, this guide will clear all of your doubts, because we are going to cover all the details: types, signs, causes, diagnosis, and treatment.

Canine skin growths and warts can be harmless or they can be the start of very serious issues like cancer, or they can simply itch and fade away. Therefore, make sure to read this expert guide from beginning to end.

A dog with skin growths can make you imagine the worst scenarios because you love your pet. It could be a tumor, a simple bump, a lymphoma or a large cyst. Because there are many variables, we have analyzed every single case separately, to help you to understand what is happening to your dog exactly. Therefore, take it easy, give this guide a read and find the answers you need.

What are Skin Growths on Dogs?

Skin growths are bumps that can appear on different parts of your dog’s body. Vets use the term “growths” instead of “tumors” when there is no diagnosis because they can be a sign of various issues. In the best cases, they can be harmless, like fatty skin growths, which are common among senior and overweight dogs.

These growths can come in the form of cysts, which are sacs filled with fluid; tumors, which are abnormal growths of cells that can be either benign or cancerous; and lumps and bumps, which are bulges. As you can see, there are different types because they vary in their appearance.

For most people, they may look the same, especially in the case of tumors and lumps. That’s why it’s important to get a proper diagnosis to determine the true nature of the skin growth. This is crucial for responsible dog owners because mast cell tumors and squamous cell carcinomas are the most common types of cancerous growths that can endanger your dog’s life.

Types of Canine Skin Growths

As we have seen, they come in different shapes, and therefore, there is a large number of skin growths with different characteristics. You will find all of them right below, properly described.

Sebaceous Cysts

They are protuberances filled with fluid, in this case, fat (sebum). The most common cause is the blockage of skin pores or hair follicles by dirt, scar tissue, infections or debris. To make it simple to understand, think of sebaceous cysts as abnormally large pimples, and fortunately, they are harmless. They require no treatment and they will disappear on their own.

Nevertheless, two types of cysts that can be problematic under very rare circumstances: Trichoblastomas and Trichoepitheliomas, because of their association with basal cell carcinoma and the existent possibility of turning into Trichoblastic carcinoma, which is a type of cancer provoked by malignant skin cells.

Therefore, if you notice that the cyst has not disappeared in 3-4 days, then you should visit the veterinarian to diagnose it properly.

Skin Tags

Skin tags are the most common type of skin growths on dogs, and they are easy to identify because:

  • They measure only a few millimeters (in rare cases up to 30mm)
  • They have the shape of a tear
  • Skin tags have the same color as the skin of your pet
  • Most of the time, they appear on areas like the neck, inside the legs or parts where skin rubs against skin

They are harmless, and therefore, they do not require treatment. Nonetheless, if you want to prevent them, then you should keep your dog away from skin irritants and pollutants. In addition, make sure to clean its skin properly.


They are a type of skin lump that presents the following features:

  • Histiocytomas are benign tumors
  • Hairless
  • Red and bright color
  • Approximately 2.5 centimeters diameter
  • They appear on the limbs, ears, neck, and head
  • Most recurrent amongst certain breeds: Bulldogs, boxers, bull terriers and greyhounds

Similar to skin tags, they are harmless and they will disappear in a couple of months. Nonetheless, you should take your dog for a check at the veterinary, because it can be confused for other malignant round cell tumors.

Squamous Cell Carcinoma (SCC)

A malignant skin growth shares the following characteristics:

  • A malignant tumor
  • Looks like a raised bump or abnormal mass of white skin
  • It necrotizes in the center and bleeds
  • Causes cancer due to uncontrolled growth of squamous cells (cells from the squamous tier of the skin)
  • SCC can appear in any part of the body because it emerges from the squamous layer of the skin because it covers the entire body of the dog
  • It is highly aggressive and invasive, and therefore, it is life-threatening

If you suspect your dog has a case of SCC, then you should visit your veterinarian as soon as possible, because it is potentially lethal if it is not treated in its early stages.

It is a very serious issue because it is recurrent, and therefore, many scientists are working to prevent it. A good example is this study that shows how the regulation of the COX-2 gene can be useful against SCC.

Malignant Melanoma

Like SCC, it is a type of skin cancer. These tumors share the following features:

  • Highly pigmented, round firm and raised
  • They attack melanocytes (pigmented cells)
  • Most common to appear in the mouth, face, eyes and mucous membranes, although they also appear parts of the body with abundant hair
  • Malignant melanoma is highly aggressive and expands quickly, especially to the lungs and liver
  • They multiply very fast, especially if the dog licks the affected zone

Due to their highly aggressive nature, it is important to seek professional help as soon as possible.

Canine Oral Growths

Canine oral growths can be benign or malignant, and as the name clearly tells, they are protuberances that appear inside the mouth or the surrounding head area.

They are not a type of tumor itself, but rather a classification, because the most common tumors that belong to this category are:

When benign, they will disappear alone. Nonetheless, if malignant, they can evolve and expand very quickly, and that is why they need early and aggressive treatment. Therefore, you should consult your veterinarian as soon as you notice an oral growth, to diagnose it properly and begin treatment if necessary.

Lipomas in Dogs

Lipomas are common skin growths of dogs and the following features characterize them:

  • They grow underneath the skin (subcutaneous)
  • Soft to the touch and not painful
  • Filled with fat (hence they are also called fatty tumors)
  • They are benign (unless they are intrusive and connect with muscle tissue)
  • Most common amongst senior dogs
  • They are usually middle-sized, but they can grow very large

Although they are harmless most of the time, they can be mistaken for malignant and dangerous tumors like mast cell tumors, hemangiosarcomas, and lymphoma. Therefore, a visit to the veterinarian might save the life of your dog.

Mast Cell Tumors in Dogs (MCT)

MCT is the most commonly found type of skin tumor in dogs (they represent 20% of cases) and it is also known as Mastocytoma. These are its main characteristics:

  • It attacks mast cells, which are a type of white blood cell responsible for protecting your dog from parasitic attacks, producing new blood cells and repairing tissues
  • MCTs can appear in any part of the skin
  • Their appearance varies a lot, but they usually look red, ulcerated and swollen
  • They cause degranulation, which increases the production of histamines excessively, resulting in life-threatening effects like anaphylaxis
  • MCTs are highly dangerous, and therefore, they require early diagnosis and immediate treatment

They are hard to diagnose yourself, and therefore, you should take your dog to the veterinarian as soon as possible.

Mammary Tumors in Dogs

Mammary tumors are more common amongst female dogs (especially if unspayed); however, male dogs can also develop them but the cases are very rare. Furthermore, they can be benign and malign. These are the main characteristics:

  • They attack the mammary glands massively – in most cases, you will find many tumors
  • They cause inflammation of the mammary tissue and produce a loss of tissue on the surface
  • If the tumors are fixed to the skin, then it is a strong indicator that they are malignant
  • If the tumors move freely – hence not attacked to the skin or body wall – then it indicates that they are benign
  • The following breeds are more likely to develop mammary gland tumors: Spaniels, Poodles, Yorkshire terriers, German Shepherds, and Maltese dogs

If malign, it can progress quickly and threat the life of your pet. In fact, this study reported the mortality rate of 80,000 female dogs with mammary tumors in Sweden, resulting in six deaths per 10,000 dogs.

Abdominal Masses

Also known as splenic tumors. They are the most common type of tumor found in the spleen, which is the abdominal organ responsible for producing and removing blood cells. These are the main features:

  • They can be benign (splenic hematomas) or malign (Hemangiosarcomas – HSA)
  • Splenic hematomas are masses of clotted blood and can be removed via surgery
  • HASs are highly dangerous and aggressive, especially because if they are visceral they become incurable. The most common treatment is tumor excision (if viable)

According to this study, 70% of cases are benign and the 30% are malign (senior dogs are the most vulnerable).

Canine Lymphoma

Lymphoma is the term used by veterinarians to classify different types of cancers that attack lymphocytes. There are 30 different types of canine lymphomas and they are similar to the non-Hodgkin lymphoma that affects humans.

These are the main characteristics of these skin growths on dogs:

  • Mediastinal – One of the rarest cases but it is very dangerous because it is caused by high-grade malignant T lymphocytes
  • Multi-centric – This type represents approximately 85% of cases. It attacks the lymph nodes and causes their rapid enlargement
  • Alimentary – It represents 10% of cases and attacks the intestines causing effects that target such area
  • Extranodal – It includes all the types of lymphomas that attack other organs like the eyes, liver, kidneys, and skin. When it targets the skin, it receives the name of cutaneous lymphoma

Because there are so many different types, it is one of the most difficult types of skin growths to treat. If you suspect your pet is a victim of canine lymphoma, you should seek professional help right now.

Causes of Skin Growths in Dogs

As you can see, skin growths are a very complex topic, because there are many types and sub-types, for example, in the case of lymphomas. Now let’s explore the causes.


Especially in the case of tumors and cancer, certain genes like the p53 proto-oncogene have been found to have a correlation with certain types of skin growths like mast cell tumors.


Certain breeds, like the German Shepherd, have a predisposition to developing certain skin growths like the nodular dermatofibrosis. Therefore, some breeds have a hereditary tendency to develop tumors and skin protuberances.


Although the causes of cancer differ a lot and there is an intense discussion about it, dogs with a poor diet, no exercise, and high-stress levels are more vulnerable to developing it, and that includes skin tumors.

Furthermore, it is worth noting that dogs with plenty of physical activity can develop skin tags due to the zones where the skin rubs against the skin because of friction. However, they are harmless.

Hygiene and Skin Care

If you want to avoid skin tags and sebaceous cysts, then you need to clean the skin of your dog properly to avoid debris and dirt from blocking the skin pores and hair follicles. Furthermore, by keeping the skincare of your dog on point, you will stop it from scratching the same area repeatedly, which can cause lesions and lead to the formation of tumors.

Chemicals and Pollutants

Certain chemicals, pollutants, and allergens can irritate the skin of your dog, which can lead to skin tags. Therefore, you should keep your dog away from them and use medicated dog shampoos, as well as hypoallergenic pet foods.

canine skin growth types
Do not self-diagnose your dog’s skin growth. There are too many types for you to assess the situation properly.

Signs of Skin Growths

There are different symptoms that can indicate that your dog might have a case of skin growths. Here you have them. We have already cited specific signs for each case, but here you have general guidelines.

Small and Large Lumps

As we have seen, small lumps like skin tags as well as large lumps like abdominal masses fall within the category of skin growths.

Red Itchy Lumps

If the lumps look red and your pet constantly scratches them, then it is another strong indicator. The most common cases that present this characteristic are Histiocytomas and mast cell tumors.

Swollen Area

If you notice that any area of the body of your dog is swollen, then it is another strong sign. The best examples of this are sebaceous cysts and mast cell tumors.

Enlarged Lymph Nodes

This is the main characteristic of lymphomas, more precisely, when they are multi-centric. Therefore, this sign is enough to give a precise diagnosis. However, it is only preliminary, because you still need to visit the veterinarian.


Although not all skin growths are painful – like Lipomas – certain cases like tumors can cause pain to your pet, which is a sign of malignant behavior.


Signs are a good starting point, but to understand what is really going on, you need a professional diagnosis. These are the most effective medical procedures to diagnose lumps and dumps.

Impression Smear

This is the most standard procedure and it consists of staining fluid (if any) from the growth to examine it. The veterinarian will use it for cytology examination because it is the best way to determine the nature and type of skin growth.

Needle Biopsy

It is one of the most effective methods because skin biopsies allow the veterinarian to examine the types of cells from the affected area. It helps to determine if it is benign or malignant with a great precision rate.

Tissue Biopsy

If soft tissue is compromised, like with sarcomas, the veterinarian could opt for a tissue biopsy, which in fact, fulfills the same goal of a needle biopsy: analyze the types of cells from the skin growth.

CT Scans and MRIs

This is another procedure used to diagnose superficial tumors. Because Magnetic Resonance Imaging (MRI) makes it possible to identify if a mass is cancerous or not, it is widely used by veterinarians in case normal biopsies do not provide enough information.

Radiography and Ultrasonography

These methods are commonly used to diagnose different types of internal masses like paraprostatic cysts, and thanks to their function, they can also be used to examine skin growths effectively.

Many lumps found on a dog’s skin are benign. Just get your vet to remove them to enhance your dog’s comfort.

Treatment for Diagnosed Skin Growths in Dogs

Based on the diagnosis, the veterinarian will opt for a specific type of treatment and bring you a prognosis. These are the most used treatments for skin growths.


It is one of the most used treatments because it allows the veterinarian to remove the affected area to combat the disease. It depends on the type of mass, and here are a few cases where it is viable:

  • Apocrine gland tumors
  • Basal cell carcinomas
  • Hemangiopericytomas
  • Cutaneous angiosarcomas
  • Trichoepitheliomas
  • Pilomatricomas
  • Abdominal masses (if it is not visceral)


If the skin growth is a malignant tumor, then chemotherapy is the treatment to use under most circumstances because it allows to attack the problem and extend survival time. To cite an example, let’s talk about malign lymphomas. The veterinarian will use chemotherapy because it affects the entire body, which is crucial for combating lymphomas because they compromise different parts of the body.

The final goal of chemotherapy is to produce remission, which happens when all the symptoms of cancer stop. Fortunately, up to 90% of dogs reach this state. Nonetheless, it is not conclusive because it requires constant monitoring to ensure that the cancer is gone.


Radiation is another common treatment for malign skin growths. However, unlike chemotherapy that involves the entire body, it is used to target specific areas like aisled tumors. It is used in combination with chemotherapy in several cases. For example, it is used to treat nontonsillar squamous cell carcinomas.

Furthermore, evidence suggests that the combination of radiation, surgery, and prednisone can combat tumors effectively. That is why veterinarians often use a combination of treatments, because cancer is a complex disease, and therefore, it needs to be attacked from different angles.


In addition to the traditional treatments, dog owners and veterinarians also suggest other solutions. Here you have the most prominent examples:

Furthermore, many owners also opt for holistic alternatives to increase the success rate of the main treatment:

Now you have in your hands the most complete guide about skin growths on dogs. As you can see, it is a complex matter, and in many cases, these protuberances can be life threating. Use this guide for reference and always seek professional veterinarian help. Obviously, avoid breeding any dog suffering from frequently occurring skin issues.

2 comments on “Skin Growths on Dogs – Types, Causes, Diagnosis, Prevention & Treatments”

  1. judy ayer

    my dog has sores all over our vet said it was from mites i need to know what to do

  2. stephanie van campen

    on my dogs(aussie shepherd 10 yrs old) there is some sort of a growth. it seems to come out of the paw to a mottled brown hard somehow attached to the paw. It wiggles a bit, she doesn’t like it when I push or pull it, going to the vet Monday. Looked at all sorts of pictures, couldn’t find one similar.

    thank you,

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