What is squamous cell carcinoma?Carcinomas are cancers that develop in cells which cover the internal organs and outer surfaces of the body. A squamous cell carcinoma is a form of skin cancer; more specifically it is a malignant tumour in the epidermal cells of the skin. The skin consists of several layers, of which the outermost layer, or epidermis, contains scale-like cells called the squamous epithelium. A squamous cell carcinoma is so named because it is an uncontrolled growth of abnormal cells originating from the squamous cells in the epidermis. Show
Squamous cell carcinomas in dogs often appear as a white skin mass or a raised lump on the skin, in the nail beds of the toes, or in the mouth. The mass may bleed or ulcerate as the condition progresses. In dogs, squamous cell carcinomas are the most frequently diagnosed carcinomas. Squamous cell carcinoma in dogs; Structure of the skin in dogs Squamous cell carcinomas are defined by their location on the body: Cutaneous squamous cell carcinoma Cutaneous is the scientific word for “related to or affecting the skin.” These are generally slow-growing yet aggressive tumours that occur in the skin, especially under-pigmented areas where hair is sparse and where there is a high rate of exposure to sunlight. Most cutaneous squamous cell carcinomas appear on the head, limbs, abdomen (underside) and perineum. Tumours appear as firm, raised, often ulcerated lesions and nodules that frequently grow outward and have a wart-like surface. Cutaneous squamous cell carcinomas are more common in older dogs, with Bloodhounds, Keeshonds, Standard Schnauzers, Standard Poodles, Basset Hounds and Collies at greatest risk. Short-coated dogs that spend lengthy periods of time outdoors also have a higher incidence. No sex predisposition has been found. Subungual squamous cell carcinoma These are slow-growing tumours that arise in the epithelial layer of the nail bed. They may occur on multiple toes and limbs, and in around 13% of cases they metastasise to the lymph nodes and lungs. This is the most common form of squamous cell carcinoma, accounting for about 50% of digital tumours in dogs. Both the fore and hind limbs are equally predisposed to tumour development. Breeds with increased incidence of Subungual squamous cell carcinoma include Giant, Standard and Miniature Schnauzers, Gordon Setters, Standard Poodles, Scottish Terriers, Kerry Blue Terriers and Briards. Generally, these are dark-haired breeds, and a dark coat colour has been associated with the occurrence of subungual squamous cell carcinomas. Females have a slightly higher rate of occurrence. Oral Squamous cell carcinoma These are squamous tumours that occur in the mouth or throat, and are most commonly located in the gums or tonsils. They can metastasise, depending on their location, and may invade the bone. Breeds with increased incidence include English Springer Spaniels and Shetland Sheepdogs, and more frequently develops in older neutered females. Symptoms of squamous cell carcinoma in dogsSymptoms may vary depending on the location of the tumour. They may also be difficult to spot or distinguish from other sores, ulcers, bumps, or lesions. Squamous cell carcinomas in dogs may be found anywhere on the body, with typical locations being the nose, toes, legs, scrotum and anus. Common symptoms of squamous cell carcinomas in dogs include:
Causes of squamous cell carcinoma in dogsIt can be difficult to identify the exact cause of squamous cell carcinomas as there are a number of genetic and environmental factors that may contribute. These are some of the risk factors which may increase the dog’s likelihood of developing squamous cell carcinoma: Age:
Exposure to ultraviolet light or sunlight:
Physical characteristics associated with increased risk:
Breed susceptibility:
Other medical conditions that may increase risk:
How is squamous cell carcinoma in dogs diagnosed? An accurate diagnosis will help in determining the outcome of squamous cell carcinoma in dogs. A thorough history of the dog’s health should be provided, and a complete blood count and blood chemistry profile should be performed to identify any abnormalities. Accurate diagnosis relies upon microscopic examination of tissue samples, as well as medical imaging such as x-rays. Physical examination:
Cytology:
Medical imaging:
PrognosisThe prognosis will vary, depending on the size and location of the tumour, as well as the probability of recurrence of the cancer in the same area or metastasis (spread) to other areas. As carcinomas are normally malignant and predominantly invasive, life expectancy is also affected by any delay in diagnosis and onset of treatment. Malignant cancers can spread to the local lymph nodes, and then throughout the body via the blood, lymph fluid and nerves. Often the immune system is compromised, which facilitates the cancer’s progress. Canine squamous cell carcinomas of the skin are typically only locally aggressive with a low potential for distant metastasis. Where the tumour is well-differentiated (the cancer cells look more like normal cells) and can be completely excised, the prognosis is favourable. Conversely, the prognosis is poor if the tumour is inoperable or poorly differentiated or has metastasised. Any recurrence is usually seen within weeks to months. Nail bed squamous cell carcinomas may recur in the same or another digit from months to years later; they also have a greater likelihood of metastasising, even after surgical removal or amputation, because they can spread up the nerves. Prognosis for oral squamous cell carcinoma depends on the location of the tumour and its rate of metastasis. If the tumour is not located in the tonsils and has not metastasised, the prognosis is positive with surgery and/or radiation treatment. However, tumours that originate in the tonsils tend to be aggressive and have a poor prognosis; they tend to spread to regional lymph nodes. Squamous cell carcinomas in dogs. Treatment for squamous cell carcinoma in dogsTreatment for squamous cell carcinomas in dogs depends upon the location of the tumour, its size, and whether it has spread. The most common form of treatment is surgical removal. If sores are diagnosed before they become cancerous, they can be treated with topical medication. If a tumour cannot be surgically removed, treatment may entail chemotherapy and / or radiation. The veterinarian will determine the best course of action. Surgical excision:Surgical excision is the primary treatment option for squamous cell carcinomas in dogs. Successful removal of the tumour depends on factors such as its size and location. Wide surgical excision, with margins of at least 2 cm around the tumour, is usually curative. Some cases will necessitate a more severe removal of tissue. For example, tumours located on the toes require amputation of the affected toe, those on the nose will require a partial removal of the nose, and if the tumour is found on the ear, part of the ear will be removed. In cases of oral tumours, the tumour and some of the underlying tissue and bone are removed; sometimes part of the jawbone is excised. Other than an altered cosmetic appearance, most dogs recover well from these surgeries. Surgery is considerably successful if the margins are clear; that is, no cancer cells are present in the outer edge of the removed tissue. Even if surgery isn’t curative, surgery can prolong survival. Radiation therapy:Radiation therapy is usually recommended in addition to surgery if the tumour is not completely removed. It may also be used as a primary treatment for inoperable tumours. Radiation is most commonly used for tumours of nose and oral cavity. Small, early-stage tumours respond best to this treatment. Chemotherapy:While squamous cell carcinomas are not generally regarded as chemo-responsive, chemotherapy may be added to therapy, depending on the circumstances. If the tumour cannot be entirely removed or is inoperable, the veterinarian may recommend chemotherapy. In these situations, the chemical treatment will keep the tumour from growing as quickly and help to make the dog more comfortable. Alternative therapies:Alternative treatment may be used where the position of the tumour precludes successful surgery, such as the nose, face, or eyelids. These include cryosurgery, a freezing technique, and photodynamic therapy, a type of light therapy. These therapies can in some cases also be used successfully where the dog has a small, superficial tumour that has not spread to other organs. On-going management and care:
In a nutshellSquamous cell carcinomas are common tumours in dogs, often appearing as a mass or raised lump on the skin, in the nail beds of the toes or in the mouth. They are malignant cancers that are typically locally aggressive, although they metastasise slowly. Tumours in the nail bed, however, grow more quickly and are more challenging to treat. The cause of a squamous cell carcinoma in dogs is difficult to determine, as there are several genetic and environmental factors that are associated with the development of the condition. Dogs that are aged 6 to 11 years old and large breed dogs with dark coats are most at risk, as are those with prolonged exposure to sunlight and those with light coloured skin and hair and sparse fur. Early recognition, diagnosis and treatment of squamous cell carcinoma are essential. Diagnosis relies on microscopic examination of the tumour. A number treatment modalities are available, depending on the size, location and spread of the tumour. The most common treatment is surgical removal of the tumour. The prognosis for dogs with squamous cell carcinomas varies. Prognosis is good for those with well-differentiated tumours that can be completely excised and have not spread; prognosis is poor for dogs with inoperable or poorly differentiated tumours or with metastasis. More informationhttps://www.petmd.com/dog/conditions/cancer/c_dg_squamous_cell_carcinoma_skin https://vcahospitals.com/know-your-pet/squamous-skin-cell-carcinoma-in-dogs https://wearethecure.org/learn-more-about-canince-cancer/canine-cancer-library/squamous-cell-carcinoma/ https://dogtime.com/dog-health/canine-cancer/55203-squamous-cell-carcinoma-dogs-symptoms-causes-treatments http://www.vetfolio.com/oncology/squamous-cell-carcinoma https://wagwalking.com/condition/skin-cancer-squamous-cell-carcinoma https://www.merckvetmanual.com/integumentary-system/tumors-of-the-skin-and-soft-tissues/epidermal-and-hair-follicle-tumors#v3280931 https://www.skincancer.org/skin-cancer-information/squamous-cell-carcinoma What happens if squamous cell carcinoma is left untreated?Untreated squamous cell carcinoma of the skin can destroy nearby healthy tissue, spread to the lymph nodes or other organs, and may be fatal, although this is uncommon. The risk of aggressive squamous cell carcinoma of the skin may be increased in cases where the cancer: Is particularly large or deep.
Is squamous cell carcinoma painful for dogs?These lesions are typically painful, and your veterinarian may prescribe pain medications. Secondary infection is also possible for which antibiotics may be required.
How long can a dog live with oral squamous cell carcinoma without treatment?Sadly, dogs who are diagnosed in later stages may only live for another 6 months to year. If not promptly treated, the prognosis for dogs with oral cancer is very poor. On average, there is a survival time of only 65 days.
Can squamous cell carcinoma go away without treatment?No, squamous cell cancer cannot "go away" on its own.
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