Bacterial infection of the breasts, also known as mastitis, is generally caused by bacteria introduced through the milk ducts into the mammary glands. Prognosis is good with early treatment, but left untreated mastitis may cause serious complications and can prove fatal. This disease usually targets either pregnant or nursing females and can cause difficulties for not only the infected dog but her pups as well.

Mastitis is a serious infection of the breast that affects mostly nursing and pregnant females. The bacteria usually infect the mammary glands by travelling up through the milk ducts. 

Symptoms of mastitis in dogs are not consigned to only the patient themselves. Signs that your nursing dog may have mastitis may come from the behavior of the nursing puppies even before obvious signs are showing in the mother. 

Types: 

The infection of the breast tissue can be caused by a number of different varieties of bacteria, and nursing creates an ideal environment for bacteria to grow and reproduce. Although the overwhelming number of mastitis sufferers are pregnant or postpartum females, swelling and infection of the breast tissue due to mastitis can occur rarely in females who are not pregnant or nursing and in males with disorders of the breast.

Bacterial infection can be introduced into the mammary gland in a number of ways. Damage to the mammary gland, even something as simple as a scratch from a nursing pup, can introduce bacteria into the area and infections already present in the body can lodge in the mammary gland and thrive. It is essential to maintain a clean environment around a nursing mother and her pups to help prevent infections and infestations. Hormonal fluctuations, changing dietary needs, and underlying stress can suppress your dog’s normal immune responses, making her more susceptible to infections during this time.

In many cases, your veterinarian will be able to diagnose mastitis simply by getting a full history from you and by physical examination of the patient. Most of the symptoms of mastitis are clearly visible or palpable, making diagnosis fairly straightforward, however, there are other conditions that may present similarly to bacterial mastitis. Even with a diagnosis, your veterinarian is likely to request some tests to determine the severity of the infection, the type of bacterium, and if it has spread to other areas of the body. Along with a complete blood count, urinalysis and biochemistry profile, your veterinarian may request an analysis of the milk or other discharge and bacterial cultures of fluids. These tests will help to determine if any sepsis has set in and will help to determine which antibiotics will be most effective at fighting the infection. Palpable lumps or cysts may need to be sampled to rule out cancers as well.

If there is any tissue damage it will need to be addressed and supportive care will be given depending on the situation. This could include pain medications, topical wound cleansers or ointments, and IV fluids. Antibiotics are generally required to clear the infection, and the choice of which specific antibiotic to use will be determined mainly by the results of the bacterial cultures. In most cases an injection of antibiotics will be given at the office and oral antibiotics will also be prescribed. In some severe cases the glands may need to be lanced and drained, and in very rare situations a mastectomy may be required.  Whether or not the puppies have to be hand fed or can continue to nurse will be determined by the type of bacteria and the severity of the infection. In many cases puppies can be allowed to continue to nurse but there are many cases in which it is better to wean the pups early. Infections that can be transmitted to the pups, teats too blocked for pups to get milk or pain induced aggressiveness from the mother can all be reasons to either hand feed or wean the pups so that they can thrive.

Make certain that your pet completes the full measure of their antibiotic medication, usually around ten days, to help prevent a relapse.  Keeping the recovering patient (and pups if applicable) in a calm and quiet environment will help speed any recovery, as will having food and water within reach of your pet. Warm compresses may need to be applied to the affected teats on a regular basis to encourage the flow of milk and relieve pressure to the area. It is essential to keep the infected area clean and apply any ointment as instructed to prevent reinfection or cracking skin.