Other diseases may cause symptoms similar to skin cancer. These must be dismissed before a proper diagnosis for skin cancer can be obtained. They may include the following:
Skin Infections Infections of the skin (bacterial or parasitic) can cause hair loss, itchiness of the skin, redness of the skin and flakiness. These signs are very similar to those found with certain types of skin cancers (lymphosarcoma). If a dog is not responding to treatment for either a bacterial or parasitic skin disease, a skin biopsy may be recommended.
Infections of the nail can cause lameness, swelling in the toe and a discharge. Both melanoma and squamous cell carcinoma can occur in the toe, usually at the nail bed and can look like an infection.
An abscess, which is caused by a bacterial infection, can cause a swelling in the skin. This can look like any number of different types of skin tumors.
Immune Mediated Diseases
Several immune mediated diseases like systemic lupus and pemphigus can cause ulcers and sores in the skin that may look cancerous. The most common areas affected by immune mediated diseases include the tips of the ears, lips, nose and footpads.
Cysts
Several different types of cysts can be found in the skin and occur as a swelling that opens and drains intermittently. The fluid that comes from a cyst can be anywhere from a clear fluid to a thick "toothpaste" type material.
Trauma
An injury to the skin can look like certain skin cancers. You should seek veterinary attention if a suspected injury does not heal within a reasonable amount of time.
