Respiratory Infections in Small Pets

🤎 The short version: respiratory infection is one of the most common illnesses in small pets — especially rats, mice and guinea pigs — and it can progress fast. Learn the signs (sneezing, a clicking or raspy sound, laboured breathing, discharge, red tears in rats) and act promptly. Much of the prevention is in your hands: a clean, low-ammonia, dust-free, well-ventilated home. Laboured or open-mouthed breathing is always an emergency.

Why it’s so common

Small animals have delicate airways, and several are prone to specific respiratory diseases. Rats and mice are commonly affected by Mycoplasma — an infection that has no cure and can flare throughout life, worsened by stuffy, dusty or ammonia-heavy conditions. Guinea pigs are prone to pneumonia, which is a leading cause of death in the species. Because these animals are prey species that hide illness, signs can appear only once things are advanced — so early recognition matters.

The warning signs

See a vet promptly if you notice:

• Sneezing, sniffling, or a clicking / raspy breathing sound,
• Laboured or open-mouthed breathing — this is an emergency,
• Discharge from the nose or eyes,
• Red tears in rats (reddish staining around eyes/nose — a stress/illness sign, not blood),
• Loss of appetite, weight loss, a hunched posture, or a dull, puffed-up coat.

With rats and mice there’s no vaccine, so early vet care is the main defence — and a rat- or exotic-savvy vet lined up in advance makes all the difference.

Prevention: mostly husbandry

Most respiratory trouble traces back to the environment, which you control:

• Keep ammonia down. Spot-clean regularly and don’t let soiled bedding build up — for rats, low-ammonia housing directly protects their lungs.
• Use dust-free, non-aromatic bedding. Avoid fine sawdust, and never cedar or aromatic pine (the oils irritate airways); paper-based beddings are safest.
• Ventilate without draughts. Good airflow, but not a cold draught blowing across the cage.
• Avoid overcrowding and stress, and keep new arrivals separate at first (quarantine) to avoid introducing infection.
• Don’t site cages in stuffy, damp or smoky rooms.

When it’s already happening

Don’t wait it out. Early treatment helps a lot even where there’s no outright cure (as with Mycoplasma), and supportive care plus clean housing can keep an affected rat comfortable for a long time. Open-mouthed or laboured breathing means go now.

The honest takeaway

Respiratory infection is common but largely preventable: a clean, low-ammonia, dust-free, well-ventilated home does most of the work, and prompt vet care handles the rest. Watch breathing closely in rats, mice and guinea pigs, and use the health-check tool if you’re unsure. See each animal’s care guide for its specific warning signs.

Sources & further reading

• Hayfold — rat, mouse and guinea pig care guides — respiratory warning signs and housing.
• RSPCA — rats — low-ammonia housing and health.
• Merck Veterinary Manual — rats and guinea pigs — Mycoplasma and pneumonia.