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Squamous cell carcinoma is a malignant tumor located in the skin epidermal layer. It is frequently found in dogs (5% of all skin tumors) and cats (4th most common type of skin tumor). This tumor occurs in older dogs, in different locations: in the skin, nail beds, or mouth; areas where there is less pigmentation or hair. It looks like a wart: a white skin mass or raised bump on the skin, and grows slowly, being locally invasive; an inflammation is often observed as well as bleeding. This tumor rarely metastasizes.
Some breeds, short-haired and dark-colored coat pets, and pets spending time in the sun, are being more affected by this tumor. Indeed, the ultraviolet radiation induces genetic damage of cells, but does not repair the damaged DNA. The damaged cells then invade surrounding tissue. A papillomavirus may also be a cause.
They vary depending on the location: any sign of pain when walking, chewing or swallowing for example, limping, abnormal sores: inflamed, crusty or bleeding, bad odor from the mouth, erosive or ulcerated lesions, lameness, loss of the nail, swelling.
Depending on its location, it exists three different kinds of squamous cell carcinoma:
Cutaneous: located on the skin where there is less pigmentation, a lack of hair or sparse hair.
Oral: located in the mouth, on the gums, tongue or tonsils.
Subungual: located on the nailbeds.
First, to check if there are cancerous cells which would indicate the presence of metastasis through the body, a sample of the lymph gland is analyzed at the laboratory. Then, to determine the degree of malignancy, a biopsy is conducted. Finally, to verify that the organs have not been infected, or that the tumor hasn’t spread to the bone, X-rays are done.
Different treatment options are available to treat a squamous cell carcinoma. A surgery can be conducted to remove the tumor and the surrounding tissue as well as the cancer cells with it. However, when a skin grafting, amputation or partial removal of sensory organs (eye, ear, nose) may be considered it will cosmetically change the appearance of the pet. Cryotherapy kills the tumor by freezing it and may be an option. Photodynamic therapy is also a treatment for squamous cell carcinoma which consists in the administration of a photosensitizing chemical substance to kill the cancer around the treated area. Radiation and chemotherapy are also possible.
This therapy, conducted under general anesthesia, is a combination of chemotherapy (injection of anti-cancerous products) with the application of short and intense electrical impulsions on the entire lesion. The electrical field increases the temporary permeability of the cells and multiplies between 100 and 5000-fold the penetration rate and the accumulation of the cytotoxic drug (Cisplatin or Bleomycin) inside the targeted cells. According to the size and the infiltration of the tumor, one to four sessions are required with an interval of four weeks. No secondary effect has been observed. Muscular contractions without consequences can occur during the electrical impulsions.
5 publications on the treatment of squamous cell carcinoma by electrochemotherapy have already proved the efficacy of this therapy, with 1 to 2 sessions on a total of 27 cats and 3 dogs and with good results observed between 2 months and 5 years.
Cat with small squamous cell carcinoma of the
nose before treatment (2016-11-17)
Cat with small squamous cell carcinoma
of the nose after one electrochemotherapy
treatment with intralesional bleomycin
Cat with squamous cell carcinoma of the nose before treatment
Cat with squamous cell carcinoma of the nose after two electrochemotherapy treatments after three months
Cat with small squamous cell carcinoma of the nose after two electrochemotherapy treatments after six months
LEROY Biotech wants to highly thank Dr. Gary Norsworthy, Dr. Chelsea Tripp and Dr. Alice Villalobos for sharing with us the pictures of squamous cell carcinomas.