Definition
Most owners will find unexplained lumps and bumps on their dog at some point in time. Many different types of masses can appear either on (cutaneous), or just under (subcutaneous), a dog’s skin. It is important for dog owners to have these lumps checked by a veterinarian, especially if the masses are new, bleeding, oozing and/or rapidly growing. Many skin masses are harmless, but others can be malignant or become malignant and need to be taken seriously.
Causes of Skin Tumors
Canine skin masses can be caused by a number of things, such as infection (bacterial, viral, fungal), cancer (neoplasia) or simple accumulation of fat. Other forms of skin lumps include pimples, pustules, hives, hematomas, cysts, blisters (vesicles), abscesses, lick granulomas and skin tags. Some other recognized cutaneous and subcutaneous masses that can affect domestic dogs are listed below. Please remember, this is a cursory overview that is extremely generalized. Only a veterinarian can diagnose exactly what any particular lump or bump is, and what its consequences to the dog and the owner may be.
- Lipoma - Superficial uncomplicated fatty tumors called lipomas are common in dogs, especially as they grow older. These masses tend to be smooth and fairly soft beneath the skin; they almost feel like a large grape that is loose under the skin but close to its surface. Most lipomas do not require medical treatment. However, some owners opt to have them removed surgically for cosmetic reasons. Sometimes, lipomas develop stalk-like projections or extentions that connect them to nearby tissues. These are called pedunculated lipomas. While they do not usually cause particular problems in dogs, they can be quite dangerous to horses as a cause of strangulating intestinal colic.
- Papilloma – Papillomas are benign tumors that can arise from skin, mucous membranes, conjunctiva of the eyes and ducts associated with glands. They usually are not dangerous or painful. This is the common “wart”.
Squamous cell carcinoma – These tumors are often rough, reddish or grey and resemble a cauliflower. They can be ulcerated, which basically means they look like an open, oozing or bleeding wound, and they seem to be most common on the underside of affected dogs – on the belly, scrotum, legs, feet and/or muzzle.
- Basal cell tumor – Most basal cell tumors are single, hairless nodules on a narrow stem or stalk. Sometimes they are ulcerated.
- Sebaceous gland tumor/adenoma – Sebaceous adenomas are usually fairly small (often less than one inch in diameter). They tend to be smooth, pink and common on and around the eyelids and legs of older dogs.
Anal sac apocrine gland tumor – Apocrine adenocarcinomas are the most common canine anal sac tumor and are seen most commonly in older females.
- Soft tissue sarcoma – Soft tissue sarcomas can really vary in size, shape and appearance. Sometimes they grow rapidly, while other times they grow very slowly.
- Mast cell tumor – Mast cell tumors are very common in dogs. They can appear as solitary or multiple nodules and most commonly are found on the trunk, around the anus and on the legs.
Lymphoma – Lymphoma is one of the most common cancers in domestic dogs. While lymphoma is characterized by tumors of lymphoid tissue in the lymph nodes, liver, spleen, bone marrow or elsewhere, a skin (cutaneous) form causes raised, round-ish nodules that congregate in epithelial cells.
- Melanoma – Melanomas are usually darkly pigmented masses that tend to show up in dark areas of skin. When melanoma growths are found on the nail bed or in the mouth, they frequently are malignant.
- Transmissible venereal tumor – These masses occur on the genitalia of both male and female dogs. They frequently are weeping, ulcerated and rough on the surface.
- Histiocytoma – Histiocytomas are typically fast-growing, dome-shaped growths that are most common in young adult dogs.
Again, this is just a partial list of the types of lumps and bumps that an owner may notice on his dog. A veterinarian is in the best position to help owners diagnose and, if necessary, treat any skin tumors.
Prevention
There is no realistic way to prevent skin tumors. Dogs that have a primarily white coat are prone to developing malignant melanoma more commonly than other dogs and probably should not be exposed to sunlight for prolonged periods of time.
Special Notes
Skin tumors are common in domestic dogs. They may be nothing more than a cosmetic bother, but they may reflect a much more serious medical condition. Either way, dogs with skin tumors should be seen by a veterinarian.