Rat Respiratory Infection — UK Vet Guide

Respiratory disease is the most common health problem in pet rats. The underlying cause is usually _Mycoplasma pulmonis_, a bacterium carried silently by most pet rats, often passed from mother to pup. It flares into active illness when the immune system is weakened by:

• Ammonia from dirty cages — urine build-up damages the airways
• Dusty or unsuitable bedding — UK rat care guides warn against cedar and pine
• Poor ventilation, overcrowding and stress
• Other infections taking hold at the same time

Once active, infection typically moves from the nose and middle ear down into the lungs — pneumonia can follow quickly.

Porphyrin is not blood — it's a red secretion from the Harderian gland behind the eye, produced under stress and illness. Heavy staining alongside other signs means something is wrong.

Respiratory infections are treated with prescription antibiotics chosen by your vet, often alongside anti-inflammatories and nursing care. There are no safe over-the-counter substitutes, and doses must be calculated for a tiny body weight — never attempt to dose antibiotics yourself.

Be prepared for a managed condition rather than a one-off cure: mycoplasma is rarely eliminated completely, so flare-ups can recur under stress. Many rats live comfortably for their normal lifespan with prompt treatment each time.

• Clean little and often — spot-clean wet bedding daily to control ammonia; full clean regularly
• Dust-free paper bedding — avoid cedar and pine, which irritate airways
• Good ventilation without draughts
• Don't overcrowd — follow your cage's space guidance for the number of rats
• Quarantine new rats for at least two weeks before introducing them
• Feed a complete diet — good nutrition supports the immune system
• Handle and health-check daily — listen to breathing; you'll catch flare-ups early

For everyday housing, diet and companionship, see Rat care UK.