Conjunctivitis (Pink Eye) in Dogs and Cats: Causes and Treatment

What Is Conjunctivitis in Pets?

Conjunctivitis is the inflammation of the conjunctiva — the thin, transparent mucous membrane that covers the inner surface of the eyelids and the white part (sclera) of the eye. Commonly known as "pink eye," it is one of the most frequently observed eye problems in both dogs and cats, and it can range from a mild, self-limiting irritation to a symptom of a serious underlying disease. In cats especially, conjunctivitis is frequently associated with systemic infections like feline herpesvirus (FHV-1) and feline calicivirus.

Conjunctivitis in pets is not always contagious — the infectious versus non-infectious distinction depends on the underlying cause. Infectious conjunctivitis (bacterial, viral) can spread between cats and sometimes between dogs, while allergic or irritant-induced conjunctivitis does not.

Causes and Risk Factors

Infectious causes:

Feline herpesvirus type 1 (FHV-1) — the most common cause of conjunctivitis in cats
Feline calicivirus
Chlamydophila felis — a bacterial infection causing primarily conjunctivitis in cats; mildly zoonotic
Mycoplasma spp.
Bacterial infections (secondary to other causes) — Staphylococcus, Streptococcus
Canine distemper virus (in dogs)

Non-infectious causes:

Environmental irritants — dust, smoke, chemicals, air fresheners
Allergies — environmental or food-related
Foreign body — grass seed, dust particle
Entropion — eyelid rolling inward causing lashes to rub the cornea
Dry eye (keratoconjunctivitis sicca)
Trauma

Warning Signs and Symptoms

Recognizing conjunctivitis in pets:

Red, inflamed whites of the eyes
Discharge — watery and clear (irritant/allergy), or yellow/green and thick (bacterial/viral)
Squinting or keeping the eye partially closed
Pawing or rubbing at the eye
Swollen eyelids
Increased tear production — staining below the eye
Crusting around the eye edges, especially in the morning
Third eyelid protrusion — particularly in cats with herpesvirus

When to Go to the Vet Immediately

Some eye conditions look like conjunctivitis but are more serious. Seek urgent care if:

The eye appears cloudy, blue-white, or hazy — may indicate corneal ulcer or glaucoma
The pet is in visible pain — squinting tightly, extreme light sensitivity
The pupil is an unusual size or shape
The eye appears to be protruding or sinking
Symptoms appeared suddenly after a possible foreign body exposure or trauma
Symptoms are worsening despite home care

Corneal ulcers can look like conjunctivitis but require immediate treatment to prevent vision loss. Do not put off eye exams. Use the TailRounds AI Triage to assess urgency and Book a vet appointment at Happy Paws promptly for any eye concern.

At-Home Care and Monitoring

While awaiting veterinary evaluation, gentle supportive care can be provided:

Wipe away discharge gently with a clean, damp cloth — use a separate cloth for each eye
Do not use human eye drops without veterinary guidance — many are harmful to pets
Prevent self-trauma — use an Elizabethan collar if the pet is pawing at the eye
Identify and remove possible irritants from the pet's environment
Isolate cats with suspected FHV-1 or calicivirus from other cats

Veterinary treatment depends on the cause and may include topical antibiotics, antiviral eye drops (for FHV-1), L-lysine supplementation, anti-inflammatory eye drops, or addressing the underlying systemic cause. Log eye discharge color and amount, squinting frequency, and any associated signs using the TailRounds Daily Log.

Prevention and Long-Term Management

Core FVRCP vaccination reduces severity of FHV-1 and calicivirus conjunctivitis in cats
Stress management for FHV-1 positive cats — stress triggers viral reactivation
L-lysine supplementation for cats with recurrent herpetic eye disease
Regular veterinary eye exams as part of wellness visits
Reduce allergen exposure in allergic pets
Keep eyes clean and free of discharge to prevent secondary bacterial infections

Protect Your Pet's Vision with TailRounds

Eye problems can escalate quickly. Log daily eye observations using the TailRounds Daily Log and track changes in discharge, squinting, and clarity. Book a prompt exam at Book a vet appointment at Happy Paws. Find a Clinic Near You for ophthalmology referrals, and use the TailRounds AI Triage to assess whether your pet's eye symptoms need immediate attention.