Mastitis in Dogs: Recognising and Treating an Infected Nursing Mother

In this guide

A painful, sometimes life-threatening infection of the mammary glands that any nursing mother dog can develop, and one every new dog parent should know how to spot early.

Mastitis is an infection or inflammation of the mammary glands, and it almost always affects nursing mothers in the weeks after whelping. It happens when milk backs up in a gland that is not being drained properly, or when bacteria enter through small scratches on the nipple, often from a puppy's sharp claws. Left untreated, mastitis can progress from mild discomfort to a life-threatening infection within days, so early recognition matters far more than most new dog parents realise.

What Causes It

The two most common triggers are uneven nursing, where some glands are used constantly while others sit engorged and unused, and trauma from puppy nails or teeth. Bacteria such as E. coli, Staphylococcus, and Streptococcus are the usual culprits, entering through the teat and infecting the gland tissue. A dirty or damp whelping area, common during India's humid monsoon months, raises the risk further, which is why keeping bedding clean and dry is one of the simplest preventive steps a household can take.

Signs to Watch For

• One or more mammary glands feel hot, hard, swollen, or unusually painful to the touch.
• The skin over the gland looks red, purple, or in severe cases, dark and discoloured.
• Milk looks streaky, bloody, or has an odd colour and consistency instead of the usual white.
• The mother avoids letting puppies nurse from a particular gland, or seems reluctant to lie down.
• Puppies from that litter are not gaining weight as expected, often the very first clue before the mother shows obvious symptoms.
• In more advanced cases, fever, lethargy, and loss of appetite in the mother.

Treatment

Mild cases often respond to warm compresses and continued nursing or gentle milking to keep the gland draining, since blocked milk is what allows infection to take hold in the first place. Once bacteria are involved, a course of antibiotics is usually necessary, and your vet will choose one that is safe for nursing puppies, since some drugs pass into milk. Severe or abscessed glands may need to be surgically drained or, rarely, removed. If a gland is actively infected, puppies are generally kept off that particular teat and may need a short period of supplemental feeding while it heals.

Preventing Mastitis in the First Place

• Keep the whelping box clean and dry, changing bedding daily during the first couple of weeks.
• Trim puppies' nails within the first few days of life to reduce scratches.
• Watch nursing sessions occasionally to make sure all glands are being used, not just the front or back row.
• Wean gradually rather than abruptly, since sudden weaning is a common trigger for engorgement and infection.

Frequently Asked Questions

Is mastitis in dogs contagious to humans or other pets? No, but the bacteria involved can occasionally pass to puppies through infected milk, which is one reason vets keep them off an infected gland during treatment.

Can a dog get mastitis without being pregnant? It is uncommon but possible, sometimes linked to a false pregnancy or, in older unspayed females, to mammary tumours, so any unexplained mammary swelling deserves a vet visit.

How soon should I call the vet if I notice a swollen gland? The same day. Mastitis can move from mild swelling to a systemic infection within 24 to 48 hours, so it is never a wait-and-watch situation.

Article content © Ravi Teja. All rights reserved.