Respiratory disease is one of the most common ailments seen in rats at The Unusual Pet Vets. Respiratory disease can be caused by a number of different pathogens with the most most prevalent cause being a mixed bacterial infection.

Signs of respiratory disease in rats include:

  1. Sneezing
  2. Porphyria (red discharge from the eyes and nose)
  3. Increased respiratory rate or effort
  4. Weight loss
  5. Lethargy
What can I do at home?

Most rats appear to develop respiratory disease after a recent stressor in their environment. This can be moving to a new house, the introduction of a new pet or occasionally secondary to other diseases.  Rats are also sensitive to new smells in their surroundings, and some of these can be harmful over time. This includes smoking, perfumes, scented or treated woods or even build ups of their own waste (urine and faeces). For this reason, rats should be housed in open-wire cages, in rooms with plenty of ventilation. Their wastes should also be removed daily, to prevent ammonia and nitrogen fumes irritating their lungs.

How does the respiratory infection occur?

The primary pathogen involved in rat respiratory disease is Mycoplasma pulmonis. This is a commensal bacterium that populates the respiratory tract and can be present without causing disease. It is the overgrowth of Mycoplasma that is associated with pathology. As it overpopulates the trachea and nasal sinuses, the bacterium causes inflammation, which leads to a build up of respiratory secretions (mucous). This causes the affected rats to sneeze and, in some cases, start to breath faster than normal.

So my rat just has a cold?

Not exactly. Whilst Mycoplasma alone is often limited to upper respiratory tract infections, it can cause pneumonia if other bacteria or viruses are present. Pneumonia is the term used to describe inflammation (and often infection) of the lungs, and a variety of other bacteria and viruses in rats can work in conjunction with Mycoplasma, to cause this.

The main pathogens are:

  1. Corynebacterium – a gram- positive bacteria that can cause lung abscesses.
  2. Streptococcus – another gram-positive bacterium. Humans can transmit this to rats, and it can cause pneumonia, fluid accumulation in the lungs and around the heart, as well as middle ear infections in rats. 
  3. Sialdodacryoadenitis virus (SADV) – a coronavirus that can cause conjunctivitis and sneezing.
  4. Klebsiella – a gram negative bacteria that can be found in healthy rats. It can cause abscesses in a number of organs.
  5. Pasteurella – a gram negative bacteria that works synergistically with Sendai virus and mycoplasma to cause pneumonia.
  6. Sendai Virus – a paramyxovirus that slows down healing within the lungs of already sick rats.
Can you treat it?

Yes: rats with respiratory disease caused by infections can often be managed well with medications, however, it is unlikely that these medications will cure your rat. The bacteria and viruses described cause chronic changes to the lungs that are difficult to reverse, and they often promote the effects of each other. Some rats can be treated and not relapse for several months to a year, whilst other relapse in as little as a week off their medication. The severity and chronicity of the infection depends on several factors, so supporting your rat’s immune system is ideal to give them the best chance of a long, happy life.

What treatments are available?

The treatments for rat respiratory disease involve a number of medications. These include antibiotics for the bacteria involved, bronchodilators to reduce the effort needed to pull oxygen into the lungs and anti-inflammatories to reduce the inflammation occuring. Many of these medications will be required on and off throughout the rat’s life, and over time the types of medication recommended change to better suit the infection as it becomes more chronic.

Where can I find more information?

The team at Unusual Pet Vets is always happy to see new rat patients and receive questions every day on exotic animals. There are several books that provide advice on how to look after your rat, but when it comes to an unwell rat, we would always recommend they are seen by an experienced rodent veterinarian.