Inflammation of mammary tissue.

Clinical Signs

May observe the following:

  • A swelling or lumpy appearance in the area of mammary glands in a lactating doe.
  • Area may be painful and or warm to touch.
  • A poor appetite.
  • Hunched posture.
  • Doe may have stopped allowing rat pups to nurse.

*Note: for additional information on recognizing various signs of pain or discomfort refer to: Signs of Pain In Rats.


Mastitis can sometimes occur when a doe that is lactating fails to nurse her pups. This can be for reasons where the pups have been weaned to early, or if the pups have died.

With mastitis the mammary glands become engorged from the inability to nurse or express the milk. The milk then becomes stagnant which promotes the growth of bacteria, and sets up the conditions for tissue inflammation.

Additional factors that can lead to mastitis, and introduce bacteria, is pups biting at the teat creating a wound entry, or the use of abrasive litters as nesting material. Another factor is a less than sanitary
cage environment.

In septic mastitis some of the organisms that may be found are staphylococci, alpha-hemolytic streptococci, and E. coli. Progression of the infection and inflammation by these organisms may lead to the development of abscesses, or even to bacteremia and sepsis if left untreated.


Obtain history.

Perform physical exam.

Obtain milk sample by fine needle aspiration for culture and sensitivity.


Refer to the Rat Medication Guide for information on the following medications.

Place on broad-spectrum antibiotics such as: enrofloxacin, chloramphenicol, or tetracycline.
*Note: if rat pups not yet weaned avoid chloramphenicol and tetracycline.*

In the event of abscess development apply warm compresses 4 times a day to promote drainage and decrease swelling.

For an abscess that requires lancing, drain and flush the wound with normal saline wound care solution (for a saline solution at home mix 1 teaspoon of salt in 1 pint of warm water), and consider treating with trimethoprim/sulfa.

If sepsis and dehydration present institute warmed IV fluid therapy by SQ or IV.

Nursing Care

  • Maintain clean cage environment.
  • Provide clean bedding daily such as felt, soft t-shirt type material or ink-free paper towels. Avoid using material such as terry cloth type towels that can ravel. Also avoid litter-type bedding, post-op, until healed to prevent the chance of wound contamination or infection.
  • Wash hands before handling and after caring for a doe and her pups.
  • Provide additional warmth to maintain body temperature within normal limits. It is essential that the rat does not become overheated or dehydrated. The rat should also be able to move away from the heat source if it becomes uncomfortable. If the rat is unconscious or immobile extreme care must be taken to keep the heat low and stable.
    • You can use an isothermic product that is heated in the microwave such as SnuggleSafe┬«. Make sure to follow the product directions carefully and wrap in a towel before placing in the cage. SnuggleSafe┬« will provide heat for 12 hours before needing to be reheated. Other similar types of product may vary in re-heat time. Check directions for individual product.
    • If using a heating pad (good for long term use) use only the low heat setting, put a thick towel in between the pad and the cage bottom, and place beneath a corner of the cage.
    • If none of these options are available you can use a plastic bottle filled with hot water, and wrapped in a towel, in the corner of the cage.
  • Provide high calorie foods and encourage fluids while nursing or recuperating.
  • Try to refrain from having the doe nurse, if at all possible.
  • Contact veterinarian if there are any further signs of infection: swelling, redness, or pain, or if there are signs of increased weight loss, lethargy, or changes in habits.


  • Swelling reduced
  • Infection resolved
  • Pain relieved


  • Maintain a clean cage environment.
  • Wash hands before and after caring for the doe and her pups.


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