Mastitis (inflammation of the mammary glands)

Mastitis (sore breasts) can be a very unpleasant condition. Although not usually life-threatening, mastitis can be very distressing for your pet. It is important to seek veterinary advice as soon as possible because the use of antibiotics, whenever indicated by your veterinarian, can be very helpful in resolving the condition. Mastitis can worsen quickly and have serious consequences if not promptly addressed. 

©Waltham Petcare Science Institute

Mastitis means that the mammary tissue (breast tissue) is inflamed. Usually only one or two teats are affected. The most common cause is a bacterial infection that generally occurs in queens after they have given birth and while they are feeding kittens. A non-infectious mastitis may also develop when the kittens are weaned suddenly and the mammary glands become warm, swollen and hot because the milk is not being drained by feeding kittens.

In most cases the first sign you will notice is that your cat is unwilling to feed her kittens. She may snap at them when they approach. The kittens may be more restless than normal and crying because they are hungry. Your cat may have swollen and red or discolored mammary tissue which will feel hot (or in rare cases – cold) and painful to the touch. If you gently squeeze on the nipples a small amount of clotted milk or even blood or pus may be expelled. Cats with mastitis are often unwell, off their food and have a fever. In very severe cases the mammary gland may develop ulcers which ooze pus or wounds that scab over.

As disease progresses the infection may enter your cat’s bloodstream and this can cause signs of sepsis with vomiting and depression.

Your veterinarian will probably suspect that your cat has mastitis based on your description of the symptoms and the fact that they are nursing kittens. Your veterinarian will want to examine your cat and may perform an ultrasound examination of the mammary tissue; milk secretions may be collected aseptically at that time.

Tests on a milk sample will show if there is a bacterial infection. If so, a sample may be sent to a laboratory to see if bacteria can be grown so that tests can be done to find the right antibiotics to clear up the infection. If your pet has signs of general illness, such as fever or poor appetite, other tests, including blood tests, are likely to be carried out.

All breeds of cat, any age and size and new or experienced mothers are all at risk of mastitis. Mastitis usually develops from a bacterial infection that enters the breast tissue through the nipple. The risk of mastitis is higher in cats feeding in areas with poor hygiene or if there is a lot of trauma to the nipples. For this reason it is important to keep the nursing box area clean and to remove any soiled bedding as soon as possible. After kittening, cats should be closely monitored to document whether kittens are nursing on all glands. Glands that are being “neglected” may engorge with stagnated milk, predisposing them to mastitis. If that happens, assist the feeding of kittens to direct them to suckle on engorged glands.

Kittens that are very aggressive in feeding and constantly nurse, may cause the teat orifices to be constantly open, thus allowing for the entry of bacteria. If feasible, kittens, after feeding, can be kept away from the mother for a couple of hours to allow the glands to rest properly.

Rarely, the infection is spread through the blood and settles out in the mammary tissue. Mastitis can also develop in queens where milk has accumulated in mammary glands for a long period time due to kittens not feeding effectively, especially after sudden weaning or the death of kittens.

If your pet has a bacterial mastitis your veterinarian may prescribe a course of antibiotics. In most cases the problem should start to clear up within a few days of starting the treatment. It is very important that you continue to give the treatment until the course is finished, even if your cat seems completely better. If you stop treatment too early the problem may come straight back, and the tablets may not work a second time.

In some very severe cases abscesses develop in the mammary tissue or the tissue starts to die, and gangrene may develop. This is a potentially life-threatening condition and your pet will need to be admitted to hospital for intensive care and possibly surgical treatment to remove parts of the damaged mammary tissue may be required.

Your veterinarian may discuss with you whether milk suppression is required and can give medication to do this if required. This will depend on the reason for mastitis development and the stage of development of the kittens.

Your veterinarian will be able to prescribe some drugs that help to reduce the pain. The mammary tissue can be alternately packed with hot and cold dressings to reduce discomfort and inflammation and these dressings can be kept in place by putting a tee-shirt on your pet.

Initially the kittens should be removed from the mother and given supplementary milk feeding. Your veterinarian may recommend that you hand milk the affected glands every 6 hours. This keeps blood flowing to the gland to aid healing. However, it is useful to allow the kittens to suckle again quite soon to keep the mammary glands emptied. Choice of antibiotic is important as most antibiotics will cross into the milk so, if kittens are to nurse, only antibiotics safe for use in kittens can be given. If the mother is receiving antibiotics kittens must be monitored closely for signs of diarrhea or other illness and may need to be removed from the mother if they are having problems.

Most cats recover very quickly from simple mastitis, usually starting to get better within a few days, provided treatment is started quickly. However, more severe cases where emergency care is required, can be fatal and if cats do survive, the recovery from illness and surgery may be more prolonged over many weeks.