Respiratory Disease in Rats and Mice

Last Updated 2nd May 2023

This article is written by Pet Circle Veterinarian Dr Emilee Lay BVSc BSc (Vet) Hons

Rats and Mice make such great pets, however they are particularly prone to respiratory disease. There can be multiple causes and factors which influence how it affects and progresses in our pet rodents. In many instances, a complete cure is not possible, but with appropriate intervention, aggressive supportive care, and lifelong management you can help ensure they have a good quality of life. 

Respiratory diseases can occur even before you acquire them. That's why it’s always important when adopting or purchasing a rat or mouse, to thoroughly vet the facilities/practices of the breeder or store you acquire them from and do a basic health check. Are they bright, alert and well-groomed? Are they sneezing or have any abnormal breathing when handled? Is their enclosure reasonably clean with adequate ventilation? Check out our section on Finding Your Furry Friend in our Rat Care Guide. 

Read on to learn more about the causes, treatment, and prevention of respiratory diseases in our pet rats and mice! 

What Causes Respiratory Disease in Rodents?

Upper and lower respiratory disease can be caused by a range of bacteria and/or viral agents. Episodes can be triggered or worsened during periods of stress or from environmental factors that can worsen respiratory health - such as ammonia from unclean bedding, bedding material that is irritating to the airways, overcrowding and poor ventilation. 

Many of these factors feed into each other. High levels of ammonia over long periods of time can cause inflammation of the airways making them more susceptible to disease. These levels can be due to poor ventilation (avoid using glass tanks and completely enclosed plastic enclosures for this reason) and an excessive accumulation of waste in their cages. Dusty shavings or bedding material that has not undergone dust extraction can also add to irritating the airways and often have poor absorbency and odor management.

A poor diet can also result in weak immune systems, making your pet rat or mouse more susceptible to disease. Museli mixes are often rich in sugars and carbohydrates but low in key trace vitamins and minerals. Feeding a high-quality extruded pellet dry food can help minimize these issues. 

Mycoplasma is one of the main bacteria that can cause respiratory disease. In mild cases, it can cause an increased production of mucous in the airways but in severe cases, it can lead to abscesses and pneumonia of the lung. It is mainly spread via aerosolisation i.e. when affected rodents breathe and sneeze near each other, or in utero. Once established in a colony of mice or rats it is often difficult to completely eliminate. Other bacteria and viruses of concern include Streptococcus Pneumonia, CAR Bacillus, Sendai, and Siaolodacryoadenitis Virus.

What Are the Clinical Signs?

Clinical signs can vary, as prey animals rats and mice are good at hiding signs of disease until they are extremely unwell. Signs can include: 

  • Unkempt coat 
  • Weight loss
  • Increased breathing rate
  • Difficulty breathing 
  • Sneezing
  • Discharge from the nose 
  • Red discharge from the eyes, i.e. porphyrin staining 
  • Conjunctivitis 
  • Head tilt 

Regularly handling your pet mice or rat at home is essential to picking up early signs of illness or disease. If you notice a minor change in their behaviour or overall health - make sure to have it checked by a vet. 

Treatment and Prevention of Respiratory Disease

As prey animals, it's important to have your pet assessed by an experienced exotics vet as soon as possible, once you notice clinical signs. From there they can perform a physical examination and dispense appropriate antibiotics, anti-inflammatories, and other medications to help open up the airways or reduce mucous production. Remember respiratory disease is often a matter of management rather than a complete cure. Long term some animals may have mild respiratory signs or need regular nebulisation to help manage their condition. Nebulisation produces a fine vapor that can deliver medications right into the airways - and can help reduce mucous as well! You can fandangle your own nebuliser chamber at home. Make sure to speak to your exotics vet prior to nebulising your pet. 

Depending on your setup and how many rodents are affected, try and quarantine the affected animal. If this isn’t possible then ensure you have adequate ventilation, a heat source, clean- ammonia-free bedding, and nutritionally balanced, healthy, and fresh foods. 

Given the infectious nature of the respiratory disease in rats and mice, there are certain situations where an entire mousery/rattery would be treated. This is determined on a case-by-case basis and is why it's so important to have your pets assessed by an exotics vet. In the interim, you can use veterinary disinfectants to keep your enclosures clean and have high-energy pastes on standby to help support particularly unwell pets at home. 

Further Reading

Want to read more? Check out our other pocket pet articles:

Complete Rat Care Guide

How To Recognise Gut Stasis in Rabbits

Top Tips to Get Your Pet to Eat More Hay

Train Your Rabbit To Use a Litter Tray

Beginner's Guide to Guinea Pig Care

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