Does Your Pet Have Cancer?

According to the National Cancer Institute, every year, approximately 6 million new cancer diagnoses are made in dogs and a similar number in cats. With such a large population of pets being diagnosed with cancer, pet owners should be aware of cancer’s warning signs. Learn how to spot potential cancer in your dog or cat, and the cancer types most likely to affect them.

Common cancers in dogs

While numerous cancers affect dogs, the following are some of the most common:

• Lymphoma — Canine lymphoma commonly affects dogs, typically involving one or more of the external lymph nodes. Many dogs do not appear ill or have only mild signs, such as lethargy or decreased appetite, but some show more severe signs, such as weight loss, vomiting, diarrhea, excessive thirst or urination, or difficulty breathing. Often, a pet owner’s first clue is enlarged lymph nodes that have developed under the jaw, behind the knees, or in front of the shoulders. Canine lymphoma is generally responsive to chemotherapy, with up to 95% of dogs who receive the most effective treatment protocols going into remission.
• Osteosarcoma — Osteosarcomas are highly aggressive bone tumors that cause local bone damage and are prone to metastasis. Most commonly, osteosarcoma affects large- and giant-breed dogs’ limbs, but can also develop in the ribs, spine, and pelvis. Affected dogs generally limp, and may have a firm swelling on the bone. Pain medication may initially be effective, but the tumor will eventually cause more damage and sometimes the bone will fracture, and quality of life will plummet.
• Oral melanoma — Melanomas arise from pigment cells and can occur on the skin, on the toes, or in the mouth, mostly appearing as dark, raised masses. They also can cause excessive drooling, a foul odor, oral bleeding, or difficulty eating. The majority of oral melanomas in dogs are malignant, and can invade local tissue, spread to other body parts, or regrow after surgical excision.
• Mast cell tumors — Mast cell tumors are the most common canine skin tumors that can vary in appearance and often bleed easily when manipulated. Once the tumor is removed, staging is needed to determine its degree of malignancy and aggressiveness, which will guide the best treatment course.

Common cancers in cats

While cancer is diagnosed less frequently in cats than dogs, largely because fewer cats visit the veterinarian, millions of cats are still affected each year. Some of the most common cancer types in cats include:

• Lymphoma — In cats, digestive tract lymphoma, which causes vomiting, diarrhea, weight loss, and a decreased appetite, is most common. However, lymphoma can develop in lymphoid tissue anywhere in the body, and may be spurred by the feline leukemia virus (FeLV) or feline immunodeficiency virus (FIV). Lymphoma responds well to chemotherapy, and approximately 70% of treated cats will go into remission.
• Squamous cell carcinoma — Squamous cell carcinoma (SCC) is the most common oral tumor in cats and causes a foul mouth odor, oral bleeding, drooling, and difficulty eating. Surgical removal of the tumor, which can also involve removing a large portion of the jaw, is generally recommended, but because complete removal of all cancerous cells from deep mouth tissues is extremely difficult, treatment focuses on providing a good quality of life.
• Mammary tumors — Almost 90% of feline mammary tumors, which usually spread to the lymph nodes and lungs, are malignant. Surgical removal is the most effective treatment and is often curative for this cancer, unless the tumor is large or has spread.
• Fibrosarcoma — Fibrosarcoma is a soft tissue cancer that is slow to spread, but locally aggressive. Typically, you will first notice a non-painful skin mass, but your cat may become lethargic, anorexic, and dehydrated as the disease progresses. Unfortunately, surgery often does not prevent the tumor from returning.

Warning cancer signs in pets

Since so many forms of cancer can affect pets and zero in on a particular body system, determining whether your pet’s signs indicate cancer can be difficult. However, call our team if you notice that your pet has any of the following cancer warning signs:

• Swollen lymph nodes
• Lumps or bumps
• Non-healing wounds
• Appetite or weight loss
• Lethargy
• Changes in urinary or bowel movements
• Abnormal bleeding or discharge
• Lameness
• Gastrointestinal issues
• Sudden weakness or collapse
• Difficulty breathing

The sooner their cancer is diagnosed, the better your pet’s prognosis, so schedule an appointment with our Ambleside Animal Hospital team whenever you suspect your pet is showing cancer signs.