A Bump on a Dog's Rump
by A reader
Bumps on the rump are common and have many causes. The most common are small skin infections or pimples, insect bites, cysts, fatty lumps (lipomas), and skin growths. Near the tail, an infected or swollen anal gland can also cause a lump beside the anus, and flea allergy often causes bumps and scabs on the lower back.
Feel how big it is, whether it moves under the skin, and whether it is soft or firm, hot or painful, and note your dog's age. Then have your vet check it. A quick needle sample often tells what it is without anesthesia. Go sooner if it grows fast, is red and painful, or is right beside the anus.
See lumps and skin tumors on dogs.
This is general information, not a diagnosis. Please follow your own vet's advice.