Protozoal Microorganisms of the Gastrointestinal Tract in Rats

By PetMD Editorial on Jun. 19, 2010

Protozoal Infection in Rats

The digestive tract in rats is home to a wide variety of microorganisms, including protozoa, single celled organisms that play an important and beneficial role in the digestive balance. In some cases, however, protozoa can be of a parasitic variety, and can bring harm to the host animal.

Under healthy conditions the beneficial microorganisms are higher in number than the harmful microorganisms. But when a rat is stressed or in a diseased condition with a lowered immunity, the balance between the beneficial and harmful protozoa is tipped in favor of the harmful ones, which can allow for intestinal infections. There are also some species of harmful protozoa that can be transmitted to rats through various sources, most notably infected feces, and which can also lead to intestinal infections.

Protozoal infection is a relatively common finding in young rats.

Symptoms and Types

  • Weakness and lethargy
  • Lack of appetite
  • Diarrhea
  • Weight loss
  • Loss of body condition
  • Rough hair coat
  • Bleeding (which, in severe cases, can lead to death)


  • Stressful conditions
  • Lowered immunity – imbalanced intestinal bacteria and organisms
  • Contaminated feces – fecal-oral route


Your veterinarian will make an initial diagnosis by observing the rat's symptoms. He or she can then confirm the diagnosis by examining the feces under a microscope for the presence of protozoa.



Protozoal infections can generally be treated with antiprotozoal medications and broad-spectrum antibiotics. Advanced infections can lead to dehydration due to diarrhea, making it necessary to give supportive care with electrolyte-balanced fluids. Complete elimination of infectious protozoa is very difficult in some cases.

Living and Management

You will need to keep your rat under observation while it is recovering. Diarrhea and associated dehydration can lead to a severe physical condition very quickly. Keep your veterinarian updated about the progress your rat is making, and follow your doctor's advice until your rat has recovered completely.


Maintaining a clean environment seems to be the best way to prevent this condition from arising. Ensure that the bedding material in your rat’s cage is regularly changed and the cage is kept clean at all times to help prevent and overcome infections due to protozoa. It is also important to prevent stress in your rat by providing sufficient play and exercise material. Overcrowding can also stress a rat. Leaving plenty of space for movement and privacy is important for the mental wellness of your rat.


Featured Image:


Help us make PetMD better

Was this article helpful?

Get Instant Vet Help Via Chat or Video. Connect with a Vet. Chewy Health