Common skin cancers in dogs

Cancer is a major concern for canine owners because 20% of dogs will be affected by a malignant tumor during their lifetime. The most common form being the skin cancer. The main cause is solar radiation on the animal, the devastating effects of which are unfortunately still little known, many people mistakenly thinking that it is only dangerous for humans. Of course there are other factors that promote skin cancer in dogs, as we will see. Let’s take stock of the symptoms that should alert, and the most frequently diagnosed skin cancers in dogs, knowing that they affect older people more frequently but not exclusively.

Skin cancers in dogs: possible causes

As the dog’s life expectancy increases, the number of cases of skin cancer in these pets over time is increasing. Although in the current state of knowledge we do not always identify the origin, there are still many skin cancers whose cause is fully recognized, namely:

  • First cause: the sun rays,
  • Second cause: a hormonal dysfunction,
  • Other causes:
    • a virus,
    • the genetic.

The owner of the animal must know how to identify the clinical signs that may lead to suspect skin cancer.

Skin cancer in dogs: very variable symptoms

The veterinarian should be consulted as soon as any of the following signs are noticed:

  • Plaques on the skin
  • One or more nodules,
  • Growths.

These raised lesions, perceptible to the touch, evolve more or less rapidly. We can then visually see their ulceration and they can also start to bleed.

These skin changes are the result of excessive growth of tumor cells. The main problem with skin cancer is that, at the onset of the disease, the clinical signs go unnoticed in the vast majority of cases. During this time, the cancer grows. It should also be noted that apart from the cutaneous manifestations mentioned above and which can quite easily suggest cancer, other symptoms are likely to appear, far from evoking this type of pathology. These are for example:

  • Diarrhea,
  • Vomitings,
  • From increased thirst,
  • From anemia,
  • Weight loss,
  • Very tired,
  • Blood disorders.

In the presence of these signs we speak of paraneoplastic syndrome attributable to certain skin tumors only. For a breeder, this is quite confusing because it has no direct connection with the physical manifestations that are much more suggestive of skin cancer.

Finally, the dog may also exhibit the following symptoms:

  • A deformation of the muzzle, that is to say on the area between the eyes and the nose, in the event of squamous cell carcinoma,
  • Localized thickening of the subcutaneous tissue also called skin impasto,
  • Reddening of the skin all over the body and limbs.

Nothing should be overlooked, and if in doubt you should consult.

Most Common Skin Cancer Tumors in Dogs

There is not one but several skin-expressed cancers, in animals as well as in humans, since this type of pathology varies according to the cells concerned. Cancer can be cutaneous or subcutaneous. Here are the most common in dogs.


It is the most common skin malignancy in dogs since in 1 in 5 cases of skin cancer it is a mastocytoma. Its diagnosis is complex because this pathology can take different forms and its symptoms are very variable: gastric problems, weight loss, subcutaneous mass, nodule, swelling …


It is due to the dysfunction of the cells involved in the pigmentation of the skin, namely the melanocytes. A compact mass forms under the skin and it is noticeable on palpation. Melanoma represents on average 15% cases of skin cancer in canines.


He climbs to the third place skin tumors in dogs in terms of frequency, and large breed canines are most affected. It can develop in the skin or in other organs. In its cutaneous form, we speak of STM (Soft tissue sarcoma). Although it does not metastasize frequently, this very aggressive cancer can wreak havoc before being diagnosed because its symptoms are not immediately visible and are different from those of most other skin cancers. The dog has lameness, difficulty swallowing, bleeding from the mouth …

Squamous cell carcinomas

Bloody ulcers, growths, redness, are among the main manifestations, particularly in the trunk, muzzle, perineum and fingers. The UV damage are widely believed to be one of the main causes. In canines, this type of cancer represents about 5% cases of malignant skin tumors.


It takes many forms and can therefore affect different organs including the skin. In the latter case, it is a skin-expressed cancer whose symptoms are very variable such as alopecia, violent pruritus, scales and erythema, nodules, ulcerations, plaques … Several concomitant lesions can be found in a dog with cutaneous lymphoma.

Whatever the skin cancer, it is essential that a early diagnosis be established so that the dog benefits as quickly as possible from care. The sound protocol is of course defined on a case-by-case basis by the veterinarian.

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