Respiratory Disease in Rats

OVERVIEW

Many people keep pet rats (Rattus norvegicus) and one of the more common illnesses in this species is respiratory disease. Disease may remain hidden until the rat is under stress. Poor nutrition, concurrent infection, advanced age, and inadequate management can all predispose rats to respiratory disease.

CAUSES

Respiratory disease in rats is caused by a combination factors:

- genetic susceptibility of individual rats

- an immune system compromised by stress (for example, a recent move to a pet store or new home, overcrowding, and dusty, dirty housing)

- infection

Infection is not usually just one bacteria or one virus causing trouble; most often it is one bacteria, Mycoplasma, combining in different ways with other bacteria and viruses.

Once infection is established:

- respiratory secretions of fluid and mucus increase, obstructing the nasal passages and potentially filling the lungs and chest

- the mucus secretions create a biofilm lining the respiratory tract, where bacteria live protected from antibiotics

- an abnormally vigorous inflammation occurs, leading in the short term to swelling in the airways and in the long term to the lungs changing from soft, supple air-filled space to hard, dense tissue with little room for air

- occasionally the probem spreads to the inner ears, causing problems with balance, head tilt, and circling

- less commonly the problem can involve the heart or its external lining, the pericardium

SIGNS OF ILLNESS

- breathing difficulties: sneezing, wheezing, severely increased respiratory rate and effort

- nose bleeds

- decreased appetite

- debility: weight loss, poor fur quality

- sudden death

DIAGNOSIS

Our diagnosis of respiratory disease is based on the history, physical exam, and trial antibiotic therapy. X-rays are often useful to determine the extent and severity of the problem, and an echocardiogram can help us determine if the heart is involved.

TREATMENT

Treatment can include a combination of the following medications:

Antibiotics are used to control bacterial infections. Some antibiotics that are prescribed for respiratory infections can also have anti-inflammatory effects, which will further help relieve symptoms. Antibiotics commonly used include doxycycline, enrofloxacin, azithromycin and amoxycillin-clavulanic acid.

Anti-inflammatory drugs are used to control any inflammation that may be occurring in your rat’s airway. This is common in early respiratory disease or sometimes in relapses of clinical signs.

Bronchodilators dilate the airways within your rat’s lungs, allowing more air to flow through. Mucolytics act to break up the excessive mucous build up that can occur. Both of these types of medications can help rats who are having difficulty breathing to be able to breathe better.

Nebulisation Using a specialised nebulizer, which turns drugs into a vapour, medications can be directly delivered to the airways. Nebulisation can also be used to help remove mucous that can build up in airways during chronic respiratory infections. Your rat may be prescribed one or a combination of these drugs. Different combinations are picked based on the clinical signs your rat may be showing, so do not be concerned if you have not been provided with all these categories of drugs.

We treat rats that are stable (eating and acting well despite respiratory signs) as outpatients with oral antibiotics and sometimes other medications.

In most cases respiratory disease becomes chronic and requires repeated treatment with antibiotics and other medications over the rat's lifetime.

It is extremely important for the owner to provide an excellent environment:

- recycled pelleted paper bedding instead of fragrant wood chips

- an open cage rather than a closed aquarium-type one

- cage cleaned frequently to avoid urine build-up

- avoid fragrant cleaning agents, dusty environments, and tobacco smoke

PROGNOSIS

For rats that have a rapid onset of severe signs the death rate is high.

Rats that milder signs of slower onset usually develop chronic breathing problems. These problems fluctuate from mild to severe, and usually they require medical treatment, either intermittently or persistently.

CONTAGION

Most rats carry Mycoplasma and other bacteria and viruses in their respiratory tracts normally. These microorganisms are shed in their respiratory secretions, so rats kept in close contact with each other, especially young rats, are inevitably exposed to them.

Exposure to bacteria and/or viruses is very likely to occur but whether or not a rat becomes ill, and how ill it becomes, depends on other factors combining with infection. The most important other factors are the genetic susceptibilty of the individual rats and whether or not the rat's immune system is depressed by environmental stresses.

The microorganisms that are involved in rat respiratory disease are extremely unlikely to affect people, but people with poor immune system health are at increased risk. There is one report of transmission of Mycoplasma to healthy laboratory personnel.

REFERENCES:

URL: https://yarmouthvetcenter.com/rat-respiratory-disease.pml

URL: https://lafeber.com/vet/respiratory-disease-in-rats/

URL: https://www.unusualpetvets.com.au/wp-content/uploads/2020/08/rat-respiratory-disease.pdf