Conjunctivitis in guinea pigs — a red, swollen, weeping eye — is common and usually treatable, but it can signal serious underlying conditions including respiratory infection, dental root abscess, or vitamin C deficiency. A weeping eye that does not clear within 24–48 hours warrants veterinary evaluation rather than a wait-and-see approach.
Last reviewed: June 2026
What Causes Conjunctivitis in Guinea Pigs?
Conjunctivitis — inflammation of the conjunctiva, the mucous membrane lining the inner surface of the eyelid and covering the front of the eyeball — can arise from multiple causes in guinea pigs, as described in Quesenberry and Carpenter's Ferrets, Rabbits and Rodents:
- Bacterial infection: Streptococcus pneumoniae, Bordetella bronchiseptica, and Staphylococcus aureus are common causative agents; often concurrent with upper respiratory infection
- Vitamin C deficiency (scurvy): Inadequate vitamin C impairs collagen and mucous membrane integrity; conjunctivitis alongside rough coat, swollen joints, and lethargy should prompt immediate dietary correction
- Dental root disease: In guinea pigs, the molar and premolar roots extend very close to the orbit; periapical abscesses can erode into periorbital tissue, causing unilateral eye swelling and discharge that does not respond to ophthalmic antibiotics alone
- Foreign body (bedding material, hay dust): Irritation from substrate particles caught under the eyelid
- Chlamydia caviae (Chlamydophila): A zoonotic pathogen causing severe conjunctivitis with marked eyelid swelling; contagious between guinea pigs
- Environmental irritants: Ammonia from soiled bedding, cigarette smoke, dusty hay
- Trauma: Scratches from cage mates or cage wire
Signs of Guinea Pig Conjunctivitis
- Ocular discharge — ranges from clear and watery to yellow-green and thick mucopurulent
- Eyelid swelling (blepharitis) — the upper and/or lower lids appear puffy and swollen
- Crusting around the eye — dried discharge glues the lids together, especially in the morning
- Red or pink conjunctiva — visible when the eyelid is gently opened
- Squinting or partial eye closure (blepharospasm) — the guinea pig resists light or holds the eye shut to reduce pain
- Pawing at the face — rubbing at the affected eye
- Unilateral or bilateral — both eyes affected simultaneously suggests systemic or bilateral cause (infection, vitamin C deficiency); single eye suggests local cause (foreign body, dental abscess, trauma)
Diagnosis
Your exotic vet will evaluate for conjunctivitis using:
- Ophthalmic exam with staining — fluorescein stain to evaluate corneal surface for ulceration (critical — corneal ulcers require urgent treatment)
- Conjunctival swab for cytology and culture — characterizes the type of infection and guides antibiotic selection; Chlamydia caviae requires special culture media
- Skull radiographs or CT — evaluates dental roots for abscess formation; CT is superior for detecting periapical disease
- Vitamin C level assessment — clinical signs of scurvy plus dietary history; serum ascorbic acid measurement confirms deficiency
- Full physical exam — concurrent nasal discharge, lymphadenopathy, or joint swelling help identify systemic causes
The AEMV Pet Care Guides, 2024 note that Chlamydia caviae is a reportable concern in some regions and that affected guinea pigs should be isolated.
Treatment
Treatment depends on the cause:
Bacterial conjunctivitis: Topical ophthalmic antibiotic drops or ointment (chloramphenicol, tobramycin, or ciprofloxacin) applied 3–4 times daily. Concurrent respiratory infection may require systemic antibiotics (azithromycin, doxycycline, or trimethoprim-sulfa).
Chlamydia caviae: Oral doxycycline for 4–6 weeks; topical tetracycline ophthalmic ointment; all in-contact guinea pigs treated simultaneously.
Vitamin C deficiency: Immediate vitamin C supplementation — 50 mg/day for healthy adults, 100 mg/day for ill animals — via fresh foods (bell pepper, kale, parsley) and water-soluble supplements. Guinea pigs cannot synthesize vitamin C endogenously.
Dental abscess: Long-term antibiotics, dental radiography, and potentially surgical tooth removal or bulla drainage.
Foreign body: Flushing the eye with saline under sedation; the foreign material is removed and topical antibiotics are applied.
Corneal ulcer (if fluorescein-positive): Topical antibiotic ointment, pain management, and Elizabethan collar to prevent self-trauma; referral to veterinary ophthalmology if the ulcer does not resolve.
When to See a Vet
Call your vet today if:
- Your guinea pig has eye discharge or a swollen eyelid that has not improved within 24–48 hours
- The eye is closed or the guinea pig is squinting persistently
- Discharge is yellow-green or there is thick crusting
- Both eyes are affected simultaneously
- Your guinea pig's diet has been low in vitamin C
Go to the ER immediately if:
- The eyeball appears sunken, bluish, or markedly different in size compared to the other eye
- The guinea pig cannot open the eye at all and is in obvious distress
- Rapid facial swelling around the eye develops over hours
What's going on with your pet?
Describe symptoms or snap a photo. Voyage tells you urgency, home care, and whether you need a vet.
First, tell us about your pet
Breed and age make a real difference in how Voyage interprets symptoms.
Describe the symptoms
Love it? See everything Voyage can do
Frequently Asked Questions
Can conjunctivitis in guinea pigs spread to humans? Chlamydia caviae, one of the causes of guinea pig conjunctivitis, can potentially transfer to humans and cause conjunctivitis in immunocompromised individuals. Routine bacterial conjunctivitis (Streptococcus, Staphylococcus) does not typically transfer to humans. Wash hands thoroughly after handling any guinea pig with eye discharge and avoid touching your own eyes.
What is the most common cause of conjunctivitis in guinea pigs? Bacterial infection (often Streptococcus pneumoniae or Bordetella) concurrent with upper respiratory infection is probably the most common cause. Vitamin C deficiency is the second most important cause in guinea pigs with inadequate dietary vitamin C — a factor that should be considered in every case. Environmental irritants are responsible for mild transient cases that resolve quickly with improved husbandry.
Is guinea pig conjunctivitis painful? Yes. Even mild conjunctivitis causes ocular discomfort — the eye is richly innervated and inflamed tissue is painful. Blepharospasm (squinting) and pawing at the face are pain behaviors. Appropriate topical or systemic analgesics alongside antibiotics make the guinea pig much more comfortable during treatment.
How much does treating guinea pig conjunctivitis cost? An exotic vet visit with ophthalmic exam and fluorescein staining runs $80–200. Topical ophthalmic antibiotics cost $20–50. If conjunctival culture and sensitivity are needed, add $80–150. Skull radiographs or CT for dental disease screening add $150–600. Vitamin C supplementation costs pennies per day. Total uncomplicated case cost is typically $150–400; dental-associated cases requiring imaging and surgery cost $500–2,000.
Still Not Sure if Your Guinea Pig Needs a Vet?
When you're not sure if this is wait-and-see or call-tonight, Voyage AI Vet triages in under 2 minutes. Describe what you're seeing in chat, share photos of your guinea pig's eye showing the discharge or swelling, or hop on a live video call if you want a second pair of eyes. Every answer comes with citations to the actual veterinary literature it's pulling from — so you see exactly where the guidance comes from, not just a chatbot's word.