Mycoplasma Respiratory Disease
Learn what the condition is, how it may be detected early, how it is treated or managed, and which breeds or species are linked to it.
Condition snapshot
A concise guide to the condition’s pattern, detection, management and urgency.
Emergency presentation is possibleOpen-mouth breathing, severe lethargy or blue colour is an emergency.
Limit spread while seeking adviceSeparate affected animals when practical and obtain veterinary guidance on contacts, cleaning and normal mixing.
This snapshot is a general guide, not a diagnosis or treatment plan. New, severe or worsening signs require veterinary assessment.
About the condition
Mycoplasma pulmonis is a major cause of chronic respiratory disease in domestic rats and mice. Infection interacts with ammonia, viral co-infection, stress, genetics and age, producing progressive airway and middle-ear damage.
Sneezing, clicking or rattling breathing, porphyrin staining, nasal discharge, reduced activity, head tilt and weight loss occur. Some animals carry infection before signs become apparent.
Mycoplasma pulmonis is endemic in many pet rat and mouse populations and causes chronic respiratory and genital disease whose severity is shaped by genetics, age, viruses, other bacteria and air quality. The organism damages cilia and promotes progressive inflammation in nasal passages, lungs and middle ears. Porphyrin staining around the eyes or nose is a stress marker, not blood and not specific to Mycoplasma. Early clicking, sneezing or reduced activity can progress to laboured breathing, head tilt and permanent airway remodelling. An animal may carry the organism before signs appear, so introducing an outwardly healthy rodent can expose a group. High ammonia and dusty bedding amplify disease but environmental correction alone does not remove established infection. Complete eradication from a conventional colony is uncommon; goals are clinical control, reduced triggers and prevention of avoidable transmission.
Mycoplasma-associated disease in rats reflects interaction between lifelong infection, airway injury, ammonia exposure, age and secondary bacteria. Ciliary damage and bronchial remodelling make later flare-ups easier to trigger even when an initial course improves sounds and discharge. Some infected rats remain outwardly normal, so the presence of an organism does not measure the extent of lung damage. Head tilt or facial asymmetry may indicate middle-ear extension. Breeding and pet groups can maintain infection through close contact before newly acquired animals show signs. Chronic respiratory effort also increases energy demand, so weight loss can accelerate even when the rat continues approaching food.
Screening & Early Detection
Use low-dust substrate, excellent ventilation, frequent spot cleaning and quarantine. Monitor breathing sounds and body weight weekly and avoid exposure to pet-shop or wild rodents.
Diagnosis is based on history, examination, imaging and PCR or culture where useful. Complete eradication from an established colony is difficult, and other bacteria may contribute. Listen to breathing at rest and track weekly weight, activity and porphyrin staining. Review cage ventilation, stocking density, bedding dust and cleaning frequency without replacing excessive ammonia exposure with cold draughts. Chest radiographs assess lung involvement; otoscopy and imaging evaluate head tilt. PCR can support organism detection, while culture is technically difficult and coinfecting bacteria may need separate sampling. Establish whether several animals share signs and separate new or symptomatic rodents while results and treatment response are assessed.
Open-mouth breathing, severe lethargy or blue colour is an emergency. Record respiratory noise and effort at rest, because handling commonly exaggerates sounds. Thoracic imaging and weight trends help separate chronic upper-airway noise from pneumonia or cardiac disease. Review ventilation and ammonia where the animals sleep, not only immediately after a cage clean.
Treatment & Management
Veterinary treatment may combine selected antibiotics, anti-inflammatory medication, bronchodilation, nebulisation and environmental correction. Chronic structural lung damage cannot be reversed, but early treatment can improve comfort and longevity.
Use antibiotics with activity against Mycoplasma and safe dosing for the rodent species, sometimes combined to address secondary bacteria. Anti-inflammatory medication, bronchodilation, oxygen or nebulised saline may improve selected patients. Reduce ammonia through spot cleaning, appropriate enclosure size and ventilation and replace dusty substrate. Provide easily accessed food, warmth and hydration during respiratory effort. Chronic structural lung disease will not be cured by repeatedly short courses, so treatment length and maintenance decisions should follow response and relapse pattern. Monitor weight and breathing after medication stops. Animals with recurrent severe dyspnoea require quality-of-life assessment, and exposed colonies need quarantine practices rather than assuming symptom-free animals are negative.
The objective is control of active inflammation and secondary infection while limiting further airway injury; eradication is rarely a realistic promise. Improve ventilation without creating drafts and adjust bedding and cleaning frequency from measured odour and moisture. Recurrent episodes require reassessment of heart, ear and lung involvement before repeating the same regimen.
Breeds or species affected
Standard Fancy Rat
Open small mammal description, care requirements and conditions
Dumbo Rat
Open small mammal description, care requirements and conditions
Rex Rat
Open small mammal description, care requirements and conditions
Hairless Rat
Open small mammal description, care requirements and conditions
Standard Fancy Mouse
Open small mammal description, care requirements and conditions
Satin Mouse
Open small mammal description, care requirements and conditions
Longhaired Mouse
Open small mammal description, care requirements and conditions