Noticed any lesions or wart-like bumps on your dog recently? These could be squamous cell carcinoma, a malignant skin cancer that occurs in the epidermal layer of the skin. Squamous cells are found in the epidermis and abnormal cells can mutate from them, leading to an aggressive progression of cancerous tumors that can leave the surrounding tissue permanently damaged. On average, this type of cancer occurs in dogs aged between 6 and 11 years. Just like in other skin cancers, the most common cause is excessive exposure to sunlight, although genes may play a part too.
There are three types of squamous cell carcinoma: subungual, cutaneous, and oral.
Subungual squamous cell carcinoma
This is the most common type, accounting for about 50% of all cases. It is a slow-growing tumor that affects the epithelial layer of the nail bed. About 13% of cases metastasize to other areas of the body, particularly the lungs and lymph nodes. Generally, this kind of skin cancer occurs in dark-haired dogs that have a lot of sun exposure.
Breeds most likely to get squamous cell carcinoma are Briards, Gordon Setters, Kerry Blue Terriers, Giant Schnauzers, Standard Schnauzers, Miniature Schnauzers, Scottish Terriers, and Standard Poodles. Females have a higher chance of getting this disease.
Cutaneous squamous cell carcinoma
As the name suggests, this cancer occurs on the skin of the dog. Nodules and lesions are most visible on exposed areas or those that have less hair than the rest of the body. The most common places are the abdomen, head, limbs, and perineum of the affected dog. Unlike other skin cancers, cutaneous SCC has a low propensity for metastasis. It has a relatively slow, albeit aggressive, progression on the affected region. There is no known prevalence of cutaneous SCC in either female or male dogs. However, Basset Hounds, Bloodhounds, Collies, Keeshonds, Standard Poodles, and Standard Schnauzers are more susceptible to cutaneous SCC.
Oral squamous cell carcinoma
Lastly, oral squamous cell carcinoma occurs in the mouth and throat of the dog, affecting the tongue, gums, and tonsils. If it develops on the gums, it will likely affect the bone tissue found beneath the teeth. The carcinoma found on the tonsils is most likely to metastasize to other organs via the lymph nodes. The Breeds most likely to be affected include English Springer Spaniels and Shetland Sheepdogs.
As with most cancers, treatment is most successful when the tumor is detected early on. Wide surgical resection, where affected and surrounding tissue is removed, provides the best results. However, this option is less forgiving when it comes to cosmetics, as it often involves amputations and other visible operations. Alternatives include radiation, chemotherapy, and cryotherapy. If you find unusual lumps on your dog, talk to your vet as soon as possible.