One of the most common health problems in rats is respiratory illness. Treatment should be started as soon as symptoms appear, or irreversible damage may be done to the nasal passages and lungs. Infections such as pneumonia should be taken very seriously as they can kill a rat in only a few days.
Mycoplasma pulmonis (myco) is a bacteria that is found in almost every rat. When rats are young and healthy, their immune systems are able to keep the bacteria in check, but if their immune systems are weakened the bacteria can multiply and cause more damage. Symptoms of a myco flare-up or respiratory infection usually include porphyrin (red mucus) around the nose and eyes, sneezing, noisy breathing, and “coughing” (appears similar to the hiccups).
There are quite a few factors that can greatly increase the chance of a myco flare-up or infection: the use of pine or cedar shavings, ammonia from a dirty cage, smoke, chemicals or harmful fumes, vitamin A or E deficiency, stress, old age, or illness. If the myco is able to multiply enough, it will start to irritate the lining of the nasal passages and lungs, causing them to produce mucus and scar tissue. The myco can also spread to the inner ear (seen as head-tilt) or uterus/genitals.
There is no cure for myco, but respiratory infections such as pneumonia can be treated. Antibiotics, a healthy diet, a clean cage, and an environment free from stress will help keep your rat’s immune system strong and able to fight the myco. If a myco flare-up or infection occurs, you need to get antibiotics from your vet. Baytril (usually used in combination with doxycycline) is one of the more effective antibiotics against myco, but tetracycline, tylosin, and erythromycin are also capable of fighting myco and any secondary infections. Humidifiers, Bisolvon (decongestant), nebulizers, or having them in the bathroom while the shower is running can also help ease congested lungs. In most cases, eventually the myco will become resistant to treatment and the rat will not be able to breathe freely. In the late stages the rat may gasp through his/her mouth, become restless, the feet and tail tip may turn blue from lack of oxygen, and if the infection reaches the inner-ear head-tilt will also develop. When your rat’s quality of life becomes poor, euthanasia (with anesthesia given before the injection) should be considered.