Dogs may develop pus-filled bumps on their skin for a number of reasons, including infection, parasites or injury. While some conditions can lead a dog to develop large abscesses, other conditions will cause areas of smaller pustules to develop. As many conditions will require medical treatment to prevent them leading to further problems, it is a good idea to take a dog to the vet with any signs of a suspicious lump or skin condition.
Pyoderma refers to a number of conditions caused by a bacterial infection in a dog’s skin. Conditions include impetigo and acne, where the surface of the skin contracts a bacterial infection causing areas of pustules to form. Folliculitis is also caused by a bacterial infection, affecting the hair follicles and creating pustules that later develop into lesions. Pyoderma can also affect deeper layers of a dog’s skin, causing ulcerated pustules to develop. Antibiotics and specialised shampoos are common treatments for pyoderma in dogs.
Almost any injury that a dog sustains on its body can lead to an abscess forming if the wound becomes infected. Unlike surface skin infections such as impetigo, bacterium that enters a wound can cause a much deeper infection. Infected wounds often lead to large, painful abscesses that can be very uncomfortable for the dog and must be prevented from entering the animal’s bloodstream. Abscesses can be avoided by keeping dogs away from other dogs that may play roughly or be aggressive. Any wounds should also be seen by a vet to ensure that they do not become infected.
Dogs develop ringworm as the result of a fungal infection. The condition is most commonly contracted in humid weather conditions and passes between animals as spores from the site of the infection pass from the fur of one dog to the fur of another. Symptoms of ringworm include itchiness and circular red lesions which can often have pus-filled spots inside them. Anti-fungal ointment is usually prescribed by vets when a dog is diagnosed with ringworm.
Dogs can occasionally develop pus-filled lumps on the skin between their toes. These interdigital cysts can be painful for the dog and can eventually burst, releasing the liquid as the lump drains. A number of causes can lead to an interdigital cyst developing, including infection, foreign bodies entering the foot when the dog stands on something sharp or as the result of a parasite such as a mite or tick. Depending on the cause of the lump, vets may prescribe treatments including soaking the foot in a medicated solution, removal of a foreign body, a course of antibiotics or surgery.