The mammary glands are located in the fatty layer of the abdomen. The number of mammary glands an animal has depends on the species. For example, a horse has two glands, and dogs have ten. Mammary glands are actually modified sweat glands. They are composed of small sacs or acini, which are lined with secretory cells and ducts. During lactation, the glands swell, first producing colostrum, and then eventually milk.
Mastitis is typically caused by three kinds of bacteria: e-coli, staphylococcus, or streptococcus. Mastitis is most often seen in dogs during the first two weeks after delivery, but can potentially affect any animal. It may even occasionally occur in a pet experiencing a false pregnancy. There is no known breed disposition, but dogs with short legs and pendular glands seem to be at a greater risk. Mastitis is generally caused by poor hygiene, poor environmental conditions, and trauma from the puppies suckling or scratching at the teats. Mastitis may affect only one section of the mammary gland, the whole gland or multiple glands. It may also spread from one mammary gland to others.
Symptoms
Symptoms may range from none at all to dogs that are critically ill.
- Affected mammary glands are typically hot, swollen, firm to hard and may be painful to the touch
- Severely infected glands may be black in color or even ruptured, leaking a foul-smelling pussey discharge
Other signs include
- fever
- depression
- lethargy
- anorexia
- possible septic shock from the infection
- history of unhealthy puppies
Treatment depends largely on the severity of the infection, and whether the infection spreads to other mammary glands or not. Small Animal Critical Care Medicine recommends antibiotics and hot-packing the infected area for mild cases. Puppies may or may not be allowed to nurse. If they must be hand-reared, the infected mammary glands need to be milked frequently. Severe cases may also require hospitalization with intravenous fluids, antibiotics and pain medication. Surgical removal of the mammary glands may also be necessary, especially if the tissue has necrosed, or the gland has ruptured.
If treated early, prognosis is typically good and the mother will potentially be able to nurse additional litters without re-occurrence in the future. Mastitis is more likely to re-occur however, especially in dogs with severe cases. In addition, mammary cancer needs to be considered as a likely possibility in older, unsprayed females, especially if they are suffering from mastitis, and there are no puppies present.
Dosher, K. L. (2009). Mastitis. In D. Silverstein, & K. Hopper, Small Animal Critical Care Medicine (pp. 619-621). St. Louis: Saunders.
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