Cancer In Dogs And Cats

Cancer in dogs & cats

The frightening notion of cancer is not something that any affectionate pet owner would want to contemplate. Yet, regrettably, it's a harsh reality. It's projected that one out of every three dogs and one out of every five cats will contract the illness at some point in their lives, making it one of the significant causes of mortality in aged pets. On the bright side, if detected and managed promptly, many forms of cancer can have a favorable recovery prognosis.

Causes Of Cancer

If your pet is diagnosed with cancer, it's completely understandable that you'd want to comprehend its reasons. While it's challenging to pinpoint a direct correlation between cause and effect, certain aspects contributing to cancer in pets are well-known.

Genetic influences frequently contribute to disease susceptibility, with cancer being no different. Specific breeds, although not guaranteed to get cancer, exhibit higher occurrences of particular forms of the disease. Breeds like golden retrievers, Boston terriers, and boxers have an increased prevalence of mast cell tumors, while large breeds such as Great Danes, Rottweilers, and Saint Bernards are more susceptible to bone cancer. Cats don't have a specific breed that's more prone to cancer. However, white cats have a higher risk of skin cancer due to their coat color.

Apart from genetic predisposition, environmental and lifestyle components significantly contribute to cancer development. Regrettably, pets encounter various carcinogens in their everyday lives, including herbicides, insecticides, air pollutants, and second-hand tobacco smoke. Lifestyle factors associated with cancer include prolonged sun exposure, inadequate oral hygiene, obesity, and poor nutrition.

Female dogs and cats that haven't been spayed show a higher mammary and ovarian cancer prevalence. Early spaying, before the first heat in dogs and within the first six months in cats, can further decrease this risk. Male animals without being neutered are at an elevated risk of testicular cancer.

Lastly, health conditions and aging also contribute. The immune system, the body's main line of defense against diseases, loses efficiency as the body ages. In the case of cats, the feline leukemia virus and feline immunodeficiency virus are suspected to lead to cancer.

Common Cancers In pets

Cancer manifests in various ways in animals, as in humans. Some forms of cancer may be more common in certain species, and each type impacts the body differently. Here we're discussing the most frequently occurring ones, although they're not the only types of cancer that dogs and cats can develop.

Cancer In Dogs:

Cancer in Dogs

Lymphoma - this disease targets cells in the lymph nodes or bone marrow and can compromise the immune system if not addressed promptly. The initial indicator of lymphoma frequently manifests as an enlarged lymph node in the neck region.

Hemangiosarcoma is an aggressive form of blood vessel cancer that predominantly occurs in dogs. It's most often identified in the spleen, liver, or heart. However, due to the absence of early signs, it frequently goes undetected until it reaches advanced stages.

Mast cell tumors - a type of skin cancer that can also be present in the gastrointestinal or respiratory systems. This is a highly prevalent cancer in senior dogs, usually first identified as a skin abnormality or lesion.

Melanoma - this is an especially virulent type of skin cancer, typically initiating around the lips or oral cavity, though it can also manifest in the nail bed or eyes. Without intervention, it swiftly metastasizes throughout the body, impacting essential organs.

Osteosarcoma are tumors that target the bones but can also develop in the joints or lungs. This form of cancer is typically malignant and frequently occurs in larger breeds of dogs.

Mammary cancer - akin to human breast cancer- is predominantly observed in unspayed female dogs, though it can also occur in spayed females or male dogs. Approximately half of these tumors are malignant.

Cancer in Cats:

Cancer in Cats

Lymphoma - this form of blood cell cancer is the most frequently seen in cats, particularly those between 2-6 years of age or those infected with the feline leukemia virus.

Fibrosarcoma - also referred to as soft tissue sarcoma, this cancer originates in the connective tissue. Pet owners may discover a hard, growing lump beneath the skin. There's a known connection between fibrosarcoma and injections, leading to its alternate name - feline injection-site sarcoma.

Squamous cell carcinoma is a variant of skin cancer that typically forms in areas of the body lacking pigmentation or continuously exposed, such as the ears, eyelids, and nose.

Cancer Symptoms

Bumps or enlargement - tumors are often the first discernible sign of numerous types of cancer. Any peculiar growths beneath the skin should be inspected by a veterinarian, who will typically suggest extraction and biopsy to determine whether it's benign or malignant.

Persistent sores - if a skin lesion doesn't heal despite treatment with salves or antibiotics, it warrants veterinary attention.

Unusual discharge or bleeding - consistent nosebleeds or lingering discharge from the eyes or nose could be early signs of facial tumors.

Decreased appetite - while several factors can lead to reduced appetite, it could indicate the presence of gastrointestinal tumors.

Unforeseen weight fluctuations - unless attributable to dietary changes or another sickness, sudden weight loss or gain should be investigated.

Exhaustion or stamina loss - an abrupt shift in energy levels could denote a range of health issues, including cancer.

Sudden and constant lameness or rigidity - particularly in larger dog breeds, could signify bone cancer.

Difficulty breathing, urinating, or defecating - if your pet struggles with bodily functions, it might signal discomfort or cancer-induced blockages.


Cancer diagnosis in animals is not a clear-cut process, as no absolute test can conclusively affirm or deny the presence of the disease. Veterinarians typically base their preliminary diagnosis on the physical symptoms your pet has been exhibiting and then employ a series of tests to search for specific types of cancer in the impacted regions.

A physical check-up will be performed to investigate any abnormal bumps, wounds, or discharges that you, the owner, may have observed. During this stage, any bumps or wounds can undergo biopsy. For other types of cancer or hard-to-reach body parts, your pet might need a combination of procedures such as X-rays, ultrasounds, blood tests, urine tests, CT scans, or MRI scans.

Treatment And Prognosis

If your pet's cancer diagnosis has been confirmed, your veterinarian will discuss the most effective treatment options and the prospects for a complete recovery. The chosen treatment path will depend on the cancer type, the stage of the disease, and your dog or cat's overall health.

For cancers confined to a particular area, surgery is typically the most direct approach, with the objective being to excise all the tumors in one procedure. This may be complemented with chemotherapy or radiotherapy to ensure the elimination of all cancerous cells.

Chemotherapy is used for systemic cancers, such as those affecting blood cells, but it can also prevent tumors from metastasizing to other body parts. Radiotherapy is utilized when dealing with tumors that are difficult to remove surgically, such as those in the brain.

Early detection often allows many types of cancer to be effectively treated or removed, underscoring why pet owners must stay vigilant for any abnormal symptoms. Unfortunately, some cancers are untreatable or may have metastasized to an extent where treatment isn't viable. In such scenarios, your vet will propose palliative care, which aims to alleviate the discomfort caused by cancer without actively treating the disease.


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