The risk of cancer increases with age, and cancer is one of the most common problems in older dogs. The good news is that cancer, far from being a death sentence, is the single most treatable chronic disease that dogs face — when it's detected and treated early. There's no specific type of cancer that affects pugs, but common forms of cancer seen in dogs include mammary (breast) tumors, skin tumors, testicular tumors (in dogs that haven't been neutered), mouth cancer, and lymphoma.
Cancer occurs when cells grow uncontrollably on or inside the body, forming tumors. Tumors may stay in a single area of the body, or they may metastasize, meaning they spread to other parts of the body. Most types of cancer are diagnosed through a biopsy, which involves removing and studying a section of tissue. Blood tests, x-rays, and physical signs can also play a role in a diagnosis of cancer. The following physical signs can indicate cancer:
Abnormal swellings or lumps that don't go away or that grow larger
Sores that don't heal
Unusual or excessive weight loss
Lack of appetite for any length of time
Bleeding or discharge from any body opening
Unusual or bad-smelling odors
Difficulty eating or swallowing
Lack of energy
Persistent lameness or stiffness
Difficulty breathing, urinating, or defecating
Mammary tumors are the most common type of cancer in female dogs and make up 25 to 50 percent of all tumors seen in older, unspayed females. The highest incidence is in dogs older than six years. Half of all breast tumors in dogs are malignant. Breast cancer is treated surgically by removing the tumor. You can prevent or greatly reduce your female pug's risk of mammary cancer by spaying her before her first heat cycle (see Chapter 11).
Lots of older dogs develop lumps and bumps on or beneath their skin. These growths are usually harmless, but you should always have your veterinarian take a look just to be sure. Benign (harmless) tumors often seen on the surface of the skin include cysts, papillomas (warts), adenomas, and lipomas. Once your veterinarian has deemed these tumors harmless, you can just leave them alone or have them removed surgically if they affect your pug's mobility, are growing rapidly, or you just don't like the way they look.
Dogs are fortunate in that they don't suffer the same side effects from chemotherapy as people. If your pug requires chemotherapy, he won't throw up or lose his hair. You may notice, however, that he's tired for a few days afterward.
Mast cell tumors are among the most commonly seen malignant (harmful) tumors in dogs and can occur anywhere on or in the body. They look like raised, nodular masses and can feel soft or solid when touched. Mast cell tumors can occur in dogs of any age, but they usually develop when a dog is eight to ten years old. When mast cell tumors are caught early, surgical removal is the treatment of choice. Depending on the stage of the disease, your veterinarian may recommend radiation therapy to ensure that any remaining tumor cells are destroyed. Chemotherapy can be helpful in advanced stages of the disease.
Testicular tumors are common in dogs. The average age at which they develop is ten years, but they've been known to occur as early as three years and as late as nineteen years. They're often seen in dogs with retained testicles. This type of tumor can be removed surgically. Follow-up treatment with chemotherapy or radiation may be necessary if the tumor has spread. Testicular tumors are preventable entirely with neutering.
Canine malignant melanoma is the most common oral cancer in dogs and accounts for one out of twenty cancer diagnoses. This highly aggressive cancer can occur not only in the mouth but also in the nail bed and footpad.
One of the best reasons for brushing your pug's teeth on a frequent basis is so you can spot the signs of mouth cancer. Often, the signs are not recognized until the disease is advanced, making it difficult to provide effective treatment. Signs of mouth cancer include a mass on the gums, bleeding gums, bad breath, or difficulty eating. Oral cancers are diagnosed through biopsies and X-rays. Treatment requires surgery, sometimes followed by radiation therapy. Get in the habit of examining your pug's mouth, because this type of cancer requires early, aggressive treatment.
A new approach to treating canine malignant melanoma is the DNA-based vaccine studied at New York City's Animal Medical Center. The vaccine more than tripled the survival rate of the nine dogs in the study, from an expected 90 days to an average of 389 days. Four dogs survived for more than 400 days, and one was still alive after 615 days.
Unusual swellings or enlargements in the lower neck area are often the first sign of lymphoma, a tumor of the blood-forming system. Further examination may show that all of the body's lymph nodes are enlarged. A biopsy can confirm the diagnosis, but further testing in the form of blood work, a bone marrow examination, and chest and abdominal images are necessary to determine the site and magnitude of the tumor. Lymphoma responds well to chemotherapy.