What is Skin Cancer in Dogs?

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Skin Cancer In DogsWhile dog owners won’t usually worry about mast cell tumours, they’re actually among the most commonly diagnosed type of tumor in canines and present a significant threat. Luckily, there are many treatment options that you can look into and there are various ways to get an accurate diagnosis of your pet. In this article, we answer “What is skin cancer in dogs” while discussing its signs, causes, and treatment. 

What is Skin Cancer in Dogs?

Melanoma is a type of cancer that can happen as a result of melanocytes (cells that reside in your dog’s skin and mucus membranes) increasing exponentially. Unfortunately, older dogs are particularly prone to this type of skin cancer due to its aggressive oral form. Mouth melanomas account for close to 40% of all canine oral tumors. 

If you see anything suspicious with your canine companions, it’s best to walk on the side of caution. Be sure to take your pups to a veterinary pathologist for early detection of potential problems. 

Different Types of Cancer in Dogs

Just like humans, dogs can also develop different types of skin cancer which also have a similar treatment. 

Squamous Cell Carcinoma

This is the most commonly diagnosed form of skin cancer when it comes to canines. It will typically affect older animals and will often be seen in Beagles, Dalmatians, white Bull Terriers, and Whippets. Squamous cell carcinoma will usually appear as raised lumps or wart-like patches that are firm to the touch. 

They are often found on your dog’s head, rear, abdomen, and lower legs. Sun exposure and papillomavirus have both been linked as the cause of squamous cell carcinoma in dogs.

Mast Cell Tumors

These are common kinds of cancer seen in dogs and occur within the mast cells of the immune system. They can grow anywhere on different parts of the body, including their internal organs. However, some of the most common sites include the lower abdomen, limbs, and chest. 

This kind of dog skin cancer will usually be seen in dogs between 8 -10 years old, as well as certain breeds such as Boston Terriers, Rhodesian Ridgebacks, Pugs, and Boxers. All of these dogs will be at a higher risk of getting this form of cancer. 

Malignant Melanomas

Melanomas will often appear as raised bumps that can be dark in color and are often found throughout your dog’s lips, nail bed, and mouth. While most will be benign tumors, some can be malignant tumors, which will come with a high risk of reaching other organs. As such, it can pose a serious threat to your pet’s health. 

Developing melanoma is more common in male dogs compared to females, while certain breeds also face an increased risk such as Scottish Terriers and Schnauzers.    

Types of Tumors/Melanoma Seen in Dogs

There are 4 kinds of melanoma observed in dogs, all of which are discussed below. 

Oral Melanoma

According to research, up to 80% of melanoma cases are located around a dog’s mouth and are typically seen in dogs aged 10 years or over. Cocker spaniels, miniature poodles, golden retrievers, and chows are among the most commonly affected breeds. Oral melanomas are considered to be aggressive tumors and will metastasize the lungs and local lymph nodes at a high rate. 

Nailbed Melanoma

The subungual crest or the nailbed is another common location to find skin tumors — nailbed melanoma occurs in 15% to 25% of all dogs and appears as a lone lesion. Dogs will often limp on the affected foot, and the owner may find discharge, swelling, and bleeding coming from the dog’s toes. These will behave like oral melanomas and will spread quickly around their limbs.     

Dermal Melanoma

Dermal melanomas will often appear as a dark-colored dermal mass that can appear on its own or in batches. In rare cases, these can invade the tissues even more deeply, and subcutaneous melanomas can also appear. When confined with hair, these appear to be benign in most cases and can be completely cured with surgical removal. Determining the tumor’s location along with a biopsy report can help to find out if additional diagnostic testing will be needed after removing the tumor.  

Ocular Melanoma

Melanoma of the eye can affect the canine sight as a result of conjunctival and eyelid masses. Fortunately, ocular melanocytic tumors are often found to be benign in dogs, but they can still cause problems for their eyes as they get older. Moreover, malignant melanoma in other areas of the body may have the chance to reach the eye and metastasize. 

How to Diagnose Skin Cancer in Dogs? 

Should your vet suspect that your dog might have skin cancer, they could do a fine needle aspiration which takes a small sample of the tumor. Alternatively, they could perform a biopsy to study a portion of the tumor — these are sent to a laboratory for examination to provide you with an accurate diagnosis of your dog. After an initial diagnosis of the type of cancer, additional tests will be done to see the extent of cancer around the body. 

Doing this will help your veterinary oncologist come up with the best solution that will be the most suitable for your dog’s health. 

Treating Skin Cancer in Dogs 

Dogs that are diagnosed with skin cancer during its early stages will often undergo successful treatment and go on to live healthy lives. They will often be exposed to treatment combinations and different therapies which include radiation therapy, palliative care, immunotherapy, chemotherapy, or targeted therapies. Providing a prognosis for your dog will depend on various factors, including the location of the tumor, the kind of tumor, and how far it has advanced. 

Monitoring Your Dog’s Health

Recognizing the signs of skin cancer while in its early stages is the key to coming up with good treatment outcomes. Pet parents should familiarize themselves with bumps, lumps, and rashes which they should observe during their regular grooming routine along with routine wellness exams, which should be done twice a year. Doing these can help catch cancer on the dog’s skin before it gets worse.

Should you notice any swelling around your dog’s feet or see an unusual lump on your dog, be sure to contact your vet to get medical advice.      


A cancerous tumor can affect all dog breeds and should never be ignored. While genetic factors play a role in determining whether your dog will develop one, your four-legged friend may also get one through sun exposure, and viruses. Checking your dog’s lumps is the best way to determine if they are harmful or not — the good news is that early detection can give your dog the best chance at a normal life.