URI Progression Without Treatment
| Sign | Early Stage | Late Stage | Action Needed |
|---|---|---|---|
| Nasal Discharge | Clear, watery | Thick, colored | Vet if persists >12 hrs |
| Sneezing | Occasional | Frequent fits | Monitor and separate |
| Eye Discharge | Mild crust | Sealed shut | Vet immediately |
| Breathing | Slightly fast | Labored, open-mouth | Emergency vet now |
| Behavior | Hiding more | Hunched, not eating | Critical — ER |
| Weight | Stable | Rapid loss | Tube feeding needed |
URI Emergency Protocol
URI Prevention Checklist
| Do | Keep enclosure away from drafts and temperature swings |
| Do | Maintain 65-75°F temperature range |
| Do | Clean enclosure regularly to reduce ammonia |
| Do | Quarantine new guinea pigs for 14 days |
| Do | Avoid keeping rabbits near guinea pigs (carry Bordetella) |
| Avoid | Wait for URI to resolve on its own |
| Avoid | Use antibiotics without vet guidance |
| Avoid | House with rabbits — rabbits carry Bordetella asymptomatically |
Upper respiratory infections (URI) in guinea pigs are among the most serious acute health emergencies in the species. Guinea pigs are obligate nasal breathers -- they cannot breathe through their mouths -- which means even partial nasal blockage from infection causes respiratory distress rapidly. Unlike URI in dogs or cats, guinea pig respiratory infections can progress from mild sneezing to severe respiratory compromise and death within 48-72 hours. Any guinea pig showing nasal discharge, labored breathing, or refusal to eat requires same-day veterinary evaluation.
Why Guinea Pig Respiratory Infections Are Uniquely Dangerous
The primary bacterium causing guinea pig URI is Bordetella bronchiseptica -- the same organism that causes kennel cough in dogs. The difference is that dogs typically recover from Bordetella with supportive care; guinea pigs develop rapidly fatal pneumonia. B. bronchiseptica can be carried subclinically by dogs, cats, and rabbits in the household and transmitted to guinea pigs through aerosol contact. A dog recovering from kennel cough is actively shedding B. bronchiseptica and can infect guinea pigs in the same home.
Streptococcus pneumoniae also causes severe respiratory infections in guinea pigs with high mortality. Other pathogens include Pasteurella multocida, Pseudomonas, Klebsiella, and various respiratory viruses (including adenovirus and parainfluenza). The common thread: guinea pigs have limited respiratory reserve due to their small lung volume relative to body weight, and any infection that reduces airway patency (the openness of the airway) rapidly leads to oxygen deficit and circulatory failure.
Clinical Signs: What to Watch For
Early signs (act today): Sneezing more than occasionally; nasal discharge (any amount, any color); reduced activity or unusual quietness; reduced food and water intake; weight loss detected on weekly weighing.
Progressed signs (emergency): Labored breathing -- visible effort to breathe, flank movement exaggerated, elbows flared outward; open-mouth breathing (rare in guinea pigs, almost always serious); blue-tinged gums (cyanosis, meaning oxygen deprivation); complete refusal to eat; extreme lethargy; disorientation.
A critical clinical sign often missed: tilted head or loss of balance may indicate inner ear involvement from ascending infection, which requires different antibiotic coverage.
Treatment
URI in guinea pigs requires veterinary antibiotic treatment. Common choices include: trimethoprim-sulfa (TMP-SMZ, 30 mg/kg twice daily, commonly used and well-tolerated); enrofloxacin (5-10 mg/kg twice daily, effective against many gram-negative organisms including Bordetella and Pasteurella); and chloramphenicol (used for resistant organisms but requires monitoring). Duration is typically 10-14 days minimum -- stopping antibiotics early because the guinea pig appears improved is a common cause of relapse and antibiotic resistance.
Critical antibiotic warnings: Never give guinea pigs antibiotics in the penicillin or cephalosporin family (amoxicillin, amoxicillin-clavulanate, ampicillin, cephalexin) -- these cause fatal dysbiosis (destruction of the GI flora) in guinea pigs, often killing them within days even if the original infection was improving. This applies also to lincomycin and erythromycin. Verify any antibiotic with an exotic mammal-experienced veterinarian before giving it.
Supportive care alongside antibiotics: nebulization with sterile saline to loosen secretions (a human nebulizer works well with appropriate dilution); warmth (sick guinea pigs lose heat rapidly; provide a heating pad under one side of the enclosure); syringe feeding with Critical Care (Oxbow) if the guinea pig stops eating voluntarily; and complete separation from other guinea pigs to prevent spread.
Prevention and Household Management
Guinea pigs should not have direct contact with dogs or cats that may carry B. bronchiseptica. During any period when a dog or cat in the household is showing respiratory symptoms (kennel cough, URI), the guinea pig should be moved to a completely separate room with its own air circulation. Quarantine new guinea pigs for at least 3 weeks before introducing them to established animals. Regular weight checks (weekly, on a kitchen scale in grams) are the most reliable early warning system -- weight loss of 50+ grams in an adult guinea pig (typical adult weight 700-1200 grams) is a clinical sign that triggers a vet visit even when the animal appears outwardly normal.
Sources: Harkness et al. (2010) Biology and Medicine of Rabbits and Rodents; Quesenberry & Carpenter (2012) Ferrets, Rabbits, and Rodents Clinical Medicine and Surgery; Merck Veterinary Manual guinea pig section; BSAVA Manual of Rabbit and Rodent Medicine.