Moderate severity

Mastitis (Mammary Gland Inflammation)

Painful inflammation of one or more mammary glands in a nursing or recently-pregnant queen, usually from a blocked duct or bacterial infection — the gland becomes hot, swollen and sore.

⚠️ Common symptoms

Swollen, firm, hot mammary glandPainful to the touchDiscoloured skin over the glandAbnormal, discoloured or blood-tinged milkReluctant to nurse kittensFever, lethargy or off foodKittens crying or not gaining weight

Mastitis is inflammation of the mammary glands, seen most often in queens that are nursing a litter or have recently given birth, and occasionally in cats going through a false pregnancy. It ranges from a mild, localised inflammation of a single blocked gland to a severe, spreading bacterial infection that can make the whole cat dangerously ill.

It usually begins in one of two ways: milk stagnating in a gland that is not being emptied — for instance when kittens favour certain teats, or after a litter is weaned or lost — or bacteria entering the gland, often through a teat scratched or bitten by nursing kittens or through an unclean nesting area. The affected gland becomes swollen, firm, hot and painful, and the milk it produces may turn thick, discoloured, blood-tinged or frankly pus-like.

Mastitis matters for two patients at once. The queen may become feverish, go off her food and, in septic cases, become seriously unwell as infection spreads into the bloodstream. At the same time the kittens are at risk: a painful queen may refuse to nurse, and infected or toxic milk can make the litter ill or leave them underfed. This is why abnormal milk or a sore gland in a nursing cat is treated as a problem needing veterinary attention rather than something to watch and wait on.

Treatment centres on kitten-safe antibiotics, pain relief, and keeping the gland draining with warm compresses and gentle milking. The vet will judge whether the kittens can safely keep nursing or need hand-rearing, and will treat any abscess that forms. With prompt care most queens recover well, and the key to a good outcome is catching that hot, swollen gland early — which makes daily checking of a nursing queen's mammary glands one of the most useful things an owner can do.

🔍 Causes

Mastitis develops when milk stagnates in a gland or bacteria enter it. Common triggers include a blocked or over-full milk duct (for example when kittens favour some teats over others, or after weaning or the loss of a litter), bacteria entering through a teat scratched or bitten by nursing kittens, and poor hygiene in the nesting area. It can occasionally occur with a false pregnancy, when hormonal changes stimulate milk production without a litter to draw it off. Trauma to the gland and a run-down or ill queen raise the risk.

🛡 Prevention

Keep the queen's nesting area clean and dry, and keep kittens' nails trimmed to reduce scratches to the teats. Watch a nursing queen's mammary glands daily for any that become hard, hot or swollen, and check that kittens are using all the teats reasonably evenly. Gentle management of drying-off after weaning, and good general health and nutrition in the queen, all lower the risk.

💊 Treatment

Mastitis needs prompt veterinary care. Treatment typically includes antibiotics chosen to be safe for nursing kittens, pain relief, and warm compresses with gentle milking of the affected gland to keep it draining. The vet will advise whether kittens can keep nursing on the healthy glands or must be hand-reared, particularly if an abscess forms or the milk is infected. A gland that develops an abscess or dead tissue may need to be lanced, drained or surgically treated.

When to see a vet: Contact your vet promptly if a nursing or recently-pregnant queen has a swollen, hot or painful mammary gland, abnormal-looking milk, or goes off her food or seems unwell. Seek urgent care if the gland turns dark or develops an open sore, if she is feverish, collapsed or clearly very ill, or if her kittens are not thriving — septic mastitis can make a queen seriously unwell and can endanger the litter, so it should never be left to 'see how it goes'.

⚕️ Medical disclaimer

  • This information is educational only and is not a substitute for veterinary advice.
  • Symptoms overlap between conditions — only a vet can diagnose accurately.
  • Never withhold treatment or self-medicate based on information found online.
  • When in doubt, call your vet. Early intervention almost always leads to better outcomes.

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