As they age, dogs can develop small or large bumps on or beneath their skin. These papules and nodules are often nothing more than fatty tumors or skin tags, but if your dog is getting unusually lumpy or if his bumps are filled with pus or blood, contact your veterinarian. He'll need a good checkup to ensure his skin disruptions are benign.
If your dog has a flea allergy, it may only take a bite or two to cause dermatitis (skin infection). Treating the flea problem will help prevent further bites, but the existing bites may continue to itch for days, weeks or even months after the flea is gone. Your dog will scratch, chew and slurp at the itchy bumps until they dry out and bleed. This can lead to a bacterial infection, which will need to be treated with antibiotics or steroids. If your dog can't stop worrying his sore skin, you may have to ask the vet for an Elizabethan collar until the bumps have healed.
It isn't unusual for a dog to get small cuts or scrapes as he frolics in the yard, but open, bloody wounds may develop an infection that can lead to an abscess beneath the skin if left untreated. Treat your dog's wounds promptly with bacterial ointment. If you notice a bleeding or weeping abscess forming around the wound, take your dog to the vet. She'll clean and flush the abscess first. Then, she'll perform tests to determine the type of bacteria and make sure the infection has not entered your dog's bloodstream.
Blisters that Bleed
Your dog may get a blister from an improperly fitted collar or harness. If he spends a lot of time walking on hot concrete or has stepped in chemicals or rock salt, he could develop blisters on the pads of his paws or in between his toes. Sticking his snout in the wrong garbage also can be dangerous and may lead to mouth blisters when his muzzle comes into contact with an abrasive or toxic agent. Clean your dog's blisters thoroughly with soap and warm water, then apply an antibacterial ointment, and wrap the wound, if possible. Call your vet if the wound does not show signs of healing after a day or two. Your dog may need oral antibiotics or an antifungal agent to heal.
Blistering skin also may be a sign of bullous pemphigoid, a potentially severe skin disorder that has sudden onset and may lead to secondary infections, anorexia or depression. To rule out bullous pemphigoid, your vet may biopsy your pet's skin lesions. Treatment may include antibacterial shampoos, oral antibiotics or hospitalization, if severe.
Tumors and Cancer
Not all tumors are cancerous. Some tumors are caused by a buildup of fatty tissue beneath a dog's skin, for example. But even the most benign tumor can grow cancerous over time. Take your dog to the vet if his bump becomes bloody, changes shape, oozes fluids or appears to be getting larger.
Diagnosing cancer involves a careful verbal history, physical examination, blood work, a biopsy of your dog's tumor tissue or an analysis of any fluids seeping from the bump. Treatment of a cancerous tumor will depend upon the tumor's size and type, the age and health of your dog, the stage of cancer and your dog's overall prognosis. Your vet may excise the tumor, then use limited radiation therapy to ensure the cancer does not return to the site. If the tumor has metastasized and spread to other organs, the vet may leave it in place and order chemotherapy for your pet.