Cancerous Tumors in Dogs

Tumors in dogs are common and are responsible for the highest number of deaths in canines aside from accidents. 25 percent of dogs can develop tumors during the course of their lives.

Cancerous Tumors in Dogs

Cancer or neoplasia is an overgrowth of new cells in the body that take the nutrients from the lean tissues of the body. These nutrients would have been used by the body for normal cell growth. The tumors formed by the overgrowth of cells are malignant in nature, consist of cells with varied characteristics and can spread or metastasize to different organs of the body.

Cancerous tumors can develop in any organ of your pet’s body and are generally asymptomatic until the cancer is well advanced and the tumor has grown in size.

Malignant Tumors in Dogs

Malignant tumors unlike benign ones are cancerous, fast growing and irregularly shaped. Their long tentacles make it difficult to remove these tumors surgically. They have varying degrees of invasiveness and aggressiveness. Malignant tumors in parts of the body such as the skin, liver, pancreas, lungs, central nervous system and gastrointestinal tract are known as carcinomas and those that develop in the blood vessels, urinary tract and musculoskeletal system are known as sarcomas.

Symptoms of Cancer in Dogs:

  • Loss of appetite
  • Loss of weight
  • Difficulty in breathing
  • Difficulty in swallowing
  • Difficulty in passing urine or defecating
  • Bleeding or discharge from the mouth, nose, ears or rectum
  • Unpleasant odor
  • Sores that don’t heal
  • Presence of blood in urine or stool
  • Edema
  • Change in temperament
  • Depression 
  • Lethargy

Types of Cancerous Tumors in Dogs

Skin cancers that are caused due to overexposure to the sun are the most common types of cancers in dogs and include squamous cell carcinomas, mast cell tumors and fibrosarcoma. Mammary tumors are common in unspayed female dogs. Hence, a female pet should be spayed early as each menstrual cycle can increase her risk of developing mammary cancer. Prognosis depends on how quickly the cancer is diagnosed and treated. Bone cancer is common in large breeds and the most common sites are those that have suffered previous trauma.

Such cancers are aggressive and can metastasize to the lungs. Spaying or neutering your pet can increase his chances of developing bone cancer. Lymphoma is generally observed in the lymph nodes under the jaw, in the armpit and groin, and behind the knee. Nasal tumors are very aggressive and can metastasize to the brain, lungs, kidneys and lymph nodes.

Diagnosis of Tumors in Dogs

Diagnosis begins with a physical exam and medical history. Other tests that aid in the diagnosis of cancerous tumors are X-rays, exploratory surgery and biopsies.

Treatment of Malignant Tumors

Once cancer is confirmed through a biopsy, the vet can decide upon the course of treatment that’s best suited to the cancer. Internal cancerous tumors and skin cancer can be cured by surgery. Chemotherapy can also be used with or without surgery to treat several types of cancers. It consists of medications that kill all the fast growing cells in the body.

Chemotherapy can affect the entire body of your pet and can cause side effects such as vomiting, diarrhea and loss of hair. Radiotherapy is less invasive than surgery and causes fewer side effects than chemotherapy. However, it’s more expensive and involves multiple treatments over a period of several weeks.

Early diagnosis and treatment of cancerous tumors are vital as complete removal and prevention of metastasis are difficult in later stages.