A few dog breeds are particularly prone to breast cancer, including the German shepherd.
Female dogs that have never been spayed are the most likely to contract breast cancer. Because there are an array of tumor types, visual inspection won't tell a veterinarian what kind of mass a dog has. According to PetEducation.com, 50 percent of all mammary tumors are benign, or harmless. Both a biopsy, and depending on the seriousness of the tumor, a thoracic radiograph, are standard diagnostic procedures, both to determine whether the tumor is cancerous as well as whether the cancer has spread to the lymph nodes and lungs.
Diagnostics
A physical exam in which a veterinarian notices a suspicious lump will lead to a series of diagnostic tests, not the least of which is a thoracic radiograph (X-ray). When ordering X-rays, or thoracic radiographs in this case, the Merck Veterinary Manual advises three different views of the dog's torso: straight-on at the front of the chest and a profile view at both left and right. The intention is to look for metastases, or spread of any cancer, to the lungs. Needle biopsies of the tumor are considered inconclusive. Histopathology (fine examination of tissue) is the recommended course of diagnosis.
Radiographs and Recurrence
A range of mammary tumors can show malignancy. These are anaplastic carcinomas, fibrosarcomas, malignant mixed tumors, osteosarcomas, solid carcinomas and tubular adenocarcinomas, to name a few. Tumor type determines prognosis, as does tumor size and whether it has spread. Thoracic radiographs are useful not just at the time of diagnosis but during treatment, as monitoring devices. X-rays are used to check for recurrence of the cancer, says Mar Vista Animal Medical Center in Los Angeles.
Features
Dogs that develop breast cancer tend to be between the ages of 5 and 10, says PetEducation.com. When discovered, tumors take the form of inflamed spots or solid masses near the dog's nipples. Tumors underneath the skin feel not unlike small, hard baby peas. Their growth can proceed quite speedily, doubling in size over the course of about 30 days.
Significance
Canines have a total of five pairs of nippled mammary glands. These appear to the right and left across the chest and down toward the abdomen. Breast cancer is known to crop up in all five pairs of the dog's mammary glands; however, it presents by far most often in the two final glands. Also, about 50 percent of cases show multiple tumor growths, not just one.
Treatment
Treatment proceeds much like it does in human breast cancer. Surgery attempts to get all of the tumor, or tumors, with chemotherapy administered for cancer cells that might travel to distant sites. Surgery is also useful for a more complete diagnosis, because X-rays aren't necessarily fool-proof in showing the extent of a dog's disease.
