If you find pus-filled bumps on your dog, they are likely abscesses, cysts or pyodermas. However, it's possible that such a lump is a tumor, so your vet must take a sample and make a diagnosis. Never squeeze or lance these pus-filled bumps on your own. Take him to the vet for appropriate treatment.
If your dog experiences a bite or other type of wound, it could develop into an abscess. Bacteria entering the wound or a foreign object in the skin can result in abscess formation. The area around the abscess generally loses hair, and the abscess appears hot and swollen.
The abscess might burst on its own, emitting a large amount of foul-smelling pus. If the abscess hasn't ruptured, your vet can lance it. Whether it opens on its own or is lanced, an abscess requires similar treatment. Your vet will clean the abscess with a disinfectant, and prescribe antibiotics to fight infection. Deep abscesses might require installation of a drain to get rid of pus.
Cysts have a lining, filled with cheesy material or liquid. These growths generally develop in sweat glands or hair follicles. Certain cysts contain blood. These are easily mistaken for tumors. Occasionally, a cyst will rupture, and you'll find the thick material stuck on your dog's coat and a hole where the cyst was located. Some cysts will go away on their own, but most require surgical removal to eradicate them. If the cyst is simply emptied but not excised from the skin, it generally will grow back.
Pyodermas might result from a secondary bacterial infection due to canine allergies or insect bites. Dogs suffering from hypothyroidism might develop pyodermas. Your vet will perform skin scrapings and bacterial culturing to determine the pyoderma's cause. Treatment includes antibiotic therapy, often long-term. Your vet will prescribe antibacterial shampoos for your pet, who will require frequent bathing until the infection is gone. The areas around the pyoderma must be clipped. Your dog may require professional grooming if he has long hair. Getting rid of excess hair also helps rid his body of trapped bacteria.
Additional treatment focuses on the cause of the pyoderma. If he's hypothyroid, your dog requires daily thyroid pill supplementation. Flea allergies usually are managed with a topical or oral flea preventive, while food allergies require elimination diet trials until you find one that works for your pet.
You've probably dealt with acne at some point in your life. Dogs, especially young ones, can develop pimples and blackheads too. The pustules may cause discomfort and scratching. Since acne often appears on the chin or face, your dog might rub his head on the carpet or elsewhere to find relief. Don't use human acne treatments on your pet; take him to the vet for a definite diagnosis. Some skin infections, such as ringworm, can resemble acne. Your vet might recommend an antibacterial soap for treatment of acne, but most dogs outgrow the condition by the age of 1 or 2.