Posted: May 3, 2014, 11:40 a.m. EDT
The most common health problem in pet rats is respiratory disease. Most of the respiratory disease of pet rats is caused by bacterial infections and/or viral infections. The common bacteria involved include Mycoplasma, Streptococcus and Corynebacterium. Mycoplasma is the most common cause of respiratory disease in pet rats, and most pet rats have been exposed to it. Viral infections can include the Sendai virus, the rat respiratory virus, the rat coronavirus, and the pneumonia virus of mice. These bacteria and viruses produce the two major clinical syndromes: bacterial pneumonia and chronic respiratory disease.
The first symptom of a respiratory infection in a pet rat is usually sneezing. A discharge from the nose, red tears and wheezing are frequently the next signs. Any rat making noise while breathing should be treated by your veterinarian as soon as possible. Without treatment the disease will typically get worse, and weight loss, head tilt and labored breathing may develop quickly. Most cases will continue to get worse and can be fatal without treatment.
Diagnosing respiratory disease is not always easy. Older rats with heart disease or lung cancer can have similar signs. Listening to the chest with a stethoscope can help to determine if it is a heart problem or lung problem, but this is an insensitive test. Radiographs (X-rays) can also help determine if it is a heart problem or a lung problem. A CT scan or MRI would be the most accurate way to determine how much lung damage is present. A blood test can be done to test for Mycoplasma, but Mycoplasma is so common in pet rats that it can be assumed to be part of the problem. Other bacteria and viruses can certainly make a Mycoplasma infection worse.
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Rats are prone to respiratory problems, so any change in breathing or odd breathing should be investigated by your veterinarian.
Treatment for respiratory disease is frustrating. In general Mycoplasma cannot be cured, and the damage to the lungs is permanent. In young rats, bacterial pneumonia is often from a combination of Mycoplasma and Streptococcus. These cases need to be treated aggressively with an appropriate antibiotic prescribed by a veterinarian, such as Clavamox drops. Husbandry issues need to be fixed too. High ammonia levels from urine in a dirty cage can irritate the lungs and add to the inflammation in the lungs. Cedar or nonkiln-dried pine shavings can also irritate the lungs and add to the inflammation in the lungs, so they should be avoided. Likewise cigarette smoke can also irritate the lungs and add to the inflammation in the lungs. Vitamin A or E deficiencies can also add to the lung pathology and may need to be supplemented, and the diet changed to a better quality food.
In older rats, Mycoplasma has likely already caused damage to the lungs, and the rat likely has a long term problem that cannot be cured. Antibiotics like enrofloxacin (Baytril) and doxycycline are used to reduce the amount of Mycoplasma and kill the other bacteria in the lungs. These medications may be needed for a long time (one to three months). Bronchodilators like theophylline or aminophylline can be used to help with the labored breathing, and cortisone may be useful in reducing the inflammation in the lungs. If the rat is having severe respiratory distress, oxygen therapy may help. Subcutaneous (SQ) fluids with added B vitamins may also help the rat feel better sooner. Most cases will improve, but the rat will typically have permanent damage to the lungs, suffer chronic bronchitis and be prone to respiratory problems for the rest of its life. Treatment may have to be repeated frequently as the rat gets older.
Unfortunately Mycoplasma and chronic respiratory disease is very common in pet rats. Treatment can help control the clinical signs, but it is unlikely to actually cure the rat. Improving environmental factors by keeping the cage clean of urine, using appropriate bedding, avoiding cigarette smoke, and feeding a high-quality food with the recommended levels of vitamin A and E can help reduce the severity of respiratory disease.
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