Rabbits, guinea pigs, hamsters, and rats are obligate nasal breathers, meaning they breathe exclusively through their nose under normal conditions. When disease or obstruction forces them to breathe through their mouth, they are already in significant distress. Small mammal respiratory emergencies progress rapidly because these animals have high metabolic rates, small lung volumes, and a strong instinct to hide illness.

Common causes

Upper respiratory infections caused by bacteria such as Pasteurella multocida in rabbits, Bordetella bronchiseptica in guinea pigs, and Mycoplasma pulmonis in rats are among the most frequent triggers. Pneumonia, cardiac disease, heat stress, allergic reactions to dusty bedding, and thoracic masses can also compromise breathing. Hamsters may develop respiratory illness from cedar or pine shavings that release irritating aromatic compounds.

Recognizing the signs

Subtle early signs include slightly increased breathing rate at rest, nasal discharge (which may appear as crusty residue around the nostrils), sneezing, and reduced activity. Worsening signs include audible wheezing or crackling, open-mouth breathing, head tilting upward to open the airway, flared nostrils, and a visible pumping motion of the flanks. A rabbit that is mouth-breathing is in a critical state.

Emergency response

Move the animal to a quiet, well-ventilated area at a comfortable temperature. Minimize handling, as stress increases oxygen demand. If discharge is blocking the nostrils, gently wipe it away with a warm damp cloth. Transport to a veterinarian experienced with small mammals as quickly as possible. Keep the carrier ventilated and avoid covering it completely.

Veterinary treatment

Oxygen supplementation is the first priority. The vet will assess with auscultation and possibly radiographs. Treatment depends on the cause and may include antibiotics, nebulization therapy, bronchodilators, anti-inflammatory medications, and fluid support. Guinea pigs with pneumonia often need aggressive antibiotic therapy; rabbits with Pasteurella may require long-term treatment courses.

Prevention

Use dust-free, paper-based or hay-based bedding rather than softwood shavings. Maintain good ventilation without direct drafts. Keep enclosures clean to reduce ammonia buildup from urine. Quarantine new animals before introduction. Ensure adequate vitamin C for guinea pigs, as deficiency impairs immune function. Schedule wellness exams to catch subclinical infections early.

Veterinary disclaimer: This article is for general education only and does not replace an examination by a licensed veterinarian. If your small pet is breathing with difficulty, seek veterinary care immediately.