Squamous cell carcinoma is a type of skin cancer that originates in squamous epithelial cells that are present in the outer layer of the skin and in the lining of body cavities such as the mouth and throat. This type of cancer is more often seen in elderly dogs and those spending a lot of time outdoors in the sun.

Squamous cell carcinoma can develop on the skin, in the mouth and throat and on the toenail bed. Breeds with an increased risk of developing squamous cell carcinoma include Dalmatians, Bull Terriers, Beagles, Gordon Setters, Schnauzers, Scottish Terriers and Standard Poodles.

Most squamous cell carcinomas of the skin look like firm, raised, often ulcerated bumps and usually form on the head, paws, abdomen and perineum. In dogs with short hair and white skin, these tumours usually appear on the abdomen, genitals and groin.

Squamous cell carcinoma of the mouth and throat usually affects older dogs. If the cancer develops only in the mouth it will often spread to the surrounding tissue but not the lymph nodes. However, squamous cell carcinoma that occurs in the tonsil is usually fast growing and spreads quickly to the lymph nodes and lungs.

Squamous cell carcinoma of the toenail bed most often affects dogs with dark coats. Tumours usually develop slowly and can appear on multiple digits and on both the fore and hind limbs.

Causes of squamous cell carcinoma

As with most cancers, the direct cause of squamous cell carcinoma is not known but there are a few factors associated with the development of this type of cancer including prolonged sun exposure and papilloma virus.

What are the symptoms of squamous cell carcinoma?

Symptoms of squamous cell carcinoma of the skin may include:

  • sore on the skin that’s crusted over or bleeding and that doesn’t go away with antibiotics or creams
  • sores that don’t heal for several months
  • sores in areas where the hair is white or light coloured
  • white coloured growth on the skin

Symptoms of squamous cell carcinoma of the mouth and throat may include:

  • drooling (with or without presence of blood)
  • difficulty eating
  • bad breath
  • excessive weight loss
  • nagging cough
  • loose teeth
  • facial swelling

Symptoms of squamous cell carcinoma of the nail bed may include:

  • loss of nail
  • secondary infection of nail bed
  • limping

How is squamous cell carcinoma diagnosed?

As with most health problems, your vet will give your dog a thorough physical exam to rule out conditions other than cancer. A biopsy is the best way to determine if the sore or growth is squamous cell carcinoma.

In the event of a cancer diagnosis, additional tests including blood tests, urinalysis and x-rays of the chest and abdomen are usually done to determine how far the disease has progressed and whether it has spread to the surrounding tissue and/or to the local lymph nodes and lungs.

Treatment and prognosis

Treatment of squamous cell carcinoma depends on the size and number of tumours and where they are located. Small tumours may be removed by conventional surgery, cryosurgery (freezing) or a special form of light therapy called photodynamic therapy.

Larger tumours are usually surgically removed. If the entire tumour cannot be removed — usually because of its size and/or where it’s located — additional treatment such as radiation therapy or chemotherapy, may be necessary.

Dogs with squamous cell carcinoma of the mouth and have the tumors surgically removed, with or without additional treatment, have a good survival rate, usually 12 to 16 months after surgery.

Unfortunately, tumours that originate in the tonsils are usually aggressive and have a poor prognosis as they tend to spread to the regional lymph nodes.

Dogs with squamous cell carcinoma of the nail bed will require amputation of the affected toe(s). Most dogs recover well from surgery and are back to playing and doing the things they love quickly.

In some cases, this type of cancer will reoccur so it’s important to take your dog in to the vet for a regular check up.

Sources:

This page has been reviewed by our Panel of Experts for accuracy. Our Panel of Experts is comprised of practitioners with varying specialties and perspectives. As such, the views expressed here may not be shared by all members of our Panel.

The content on this website is for informational purposes only and is not intended to be a substitute for professional veterinary medical advice, diagnosis or treatment.