Mastoid tumours, while uncommon, can't be ruled out when your dog has a lump behind its ear. About one in four dogs will develop some type of tumour during their lives. Mastoid tumours occur around the mastoid bone, on the lower part of the skull, almost directly behind the ear.
Because the mastoid bone is so close to the ear, dogs with mastoid tumours may display balance problems and dizziness. They may lose weight and have less of an appetite. Dogs with mastoid tumours also may be extremely lethargic, have less energy, and spend a lot of time sleeping or resting.
A veterinarian will generally attempt to diagnose mastoid tumours by aspirating cells from the growth area with a needle. If the tumour can't be aspirated, it's sometimes excised during a brief surgical procedure. Veterinarians also can diagnose tumours with advanced imaging technology, such as X-rays, CAT scans and MRI devices.
Not all mastoid tumours are cancerous. If your dog does have cancer, the primary treatment involves chemotherapy. The drug dosage will vary, depending on the exact location and extent of the tumour. Treating tumours can be expensive but generally shows good results in extending life.
Chemotherapy doesn't affect dogs like humans. They won't lose their hair, and stomach problems are much less likely to occur. Even so, dogs on chemotherapy need to be monitored closely to avoid potential problems like dehydration and anaemia. Pain medication and special diets can offset most of the worst effects of chemotherapy.
The prognosis for mastoid tumours generally is good. Many mastoid tumours are benign and require little treatment beyond removal. Malignant mastoid tumours that are discovered late pose more difficult problems. Osteosarcomas, or bone cancers generally found in larger dog breeds, are quite fatal; fortunately, these are usually found in lower extremities.