Eye Diseases in Pets: Conjunctivitis, Cataracts & Glaucoma | Vet Guide

🧠 Why Eye Health Matters (More Than “Just” Redness)

The eye is delicate: small changes can signal big problems. Conjunctivitis (surface inflammation), cataracts (cloudy lens), and glaucoma (dangerously high pressure) are among the most common and impactful conditions in dogs and cats. Left untreated, they can cause pain and permanent vision loss—sometimes in hours (glaucoma). A simple, standardized eye workup—Schirmer tear test, fluorescein stain, and tonometry—often distinguishes common, fixable problems from emergencies. Today’s Veterinary Practice

🧬 Eye Anatomy & Quick Diagnostics (What Your Vet Checks) 🧪

• Conjunctiva: the pink tissue lining eyelids and covering the white of the eye; inflames in conjunctivitis. Merck Veterinary Manual

• Cornea: clear “window” over the eye; stained with fluorescein to find scratches/ulcers. Today’s Veterinary Practice

• Lens: focuses light; becomes opaque in cataracts (commonly diabetic dogs). MSD Vet Manual

• Aqueous humor & drainage angle: when fluid outflow is blocked, IOP rises → glaucoma. Normal IOP ~19 ±6 mmHg dogs/cats (applanation). Values significantly above normal are suspicious. Merck Veterinary Manual

• Core office tests:

  • Schirmer tear test (tears) — done before drops. Merck Veterinary Manual

  • Fluorescein stain (ulcers). Today’s Veterinary Practice

  • Tonometry (IOP). Merck Veterinary Manual

🚩 Red-Flag Eye Symptoms (Don’t Wait)

• Sudden blue/white haze, squinting, or bulging eye 😣

• Severe pain: pawing, shut eyelids, light sensitivity

• Thick yellow-green discharge or bloody discharge

• Rapidly enlarging cloudy eye or vision loss (walking into things)

These can signal ulcers, uveitis, glaucoma, or lens rupture—seek same-day care. Acute glaucoma is a true emergency; minutes–hours matter to save vision. Merck Veterinary Manual+1

🩺 Condition #1 — Conjunctivitis (“Pink Eye”) 🌸

What it is

Inflammation of the conjunctiva caused by irritants, allergens, infections (bacterial/viral—cats often herpesvirus), dry eye (KCS), foreign bodies, eyelid issues. Workups generally include Schirmer tear test, fluorescein stain, and tonometry to rule out ulcers and pressure problems. Merck Veterinary Manual+2Today’s Veterinary Practice+2

Common signs

Redness, discharge (watery → mucopurulent), squinting, rubbing, mild swelling.

Diagnosis (in clinic)

• Schirmer tear test: low values suggest KCS/dry eye as a contributor. Merck Veterinary Manual

• Fluorescein: rules out corneal ulcer (changes treatment). Today’s Veterinary Practice

• Tonometry: screens for glaucoma/uveitis masquerading as “pink eye.” Today’s Veterinary Practice

Treatment options (vet-directed)

• Bacterial: topical antibiotics.

• Viral (cats—FHV-1): antivirals (+ lubrication).

• Allergic/irritant: flush, lubricants, sometimes topical anti-inflammatories (avoid steroids if any ulcer).

• KCS/dry eye: tear stimulants (e.g., cyclosporine), lubricants.

• Remove foreign bodies, correct eyelid abnormalities. (Approach is etiology-specific per exam results.) Merck Veterinary Manual

At-home support (only after vet exam)

• Warm compress 3–5 min, 2–3×/day 😌

• Saline rinse around lids (not into eye unless advised)

• E-collar to stop rubbing

• Follow drop schedule exactly; rechecks keep you safe

🩺 Condition #2 — Cataracts (Cloudy Lens) 🌥️

What it is

An opacity of the lens that blocks light to the retina. In dogs, diabetes mellitus is a leading cause; >85% of diabetic dogs develop cataracts due to sorbitol-driven fluid shifts within the lens. MSD Vet Manual

Common signs

White/gray “cloud,” reduced vision (hesitant on stairs), bumping into objects, lens-induced uveitis (redness, squinting).

Diagnosis

Slit-lamp exam confirms lens opacity; vets also check for lens-induced uveitis and retinal health (ERG if surgery considered).

Treatment options

• Definitive: Phacoemulsification (ultrasonic lens removal) with artificial lens implant offers the best chance to restore vision, especially when done before severe inflammation or complications. Merck Veterinary Manual

• Topical anti-inflammatories for lens-induced uveitis.

• Diabetic cataracts: surgery has superior outcomes vs topical therapy alone for vision maintenance; strict diabetic control and diligent post-op care are essential. PMC+2veterinarypartner.vin.com+2

At-home/aftercare essentials

• Post-op drop regimen (antibiotic, anti-inflammatory) on schedule ⏱️

• E-collar to prevent rubbing

• Rechecks (pressure/retina) as directed

🩺 Condition #3 — Glaucoma (Pressure Emergency) 🚨

What it is

Elevated intraocular pressure (IOP) damages the optic nerve and retina. Causes: primary (breed-related drainage angle defects; many dog breeds) or secondary (uveitis, lens luxation, tumors). Normal IOP roughly ~19 mmHg (dogs/cats); significant increases are concerning. Signs: pain, corneal haze, enlarged firm eye, vision loss. Merck Veterinary Manual

Why it’s urgent

Rapid, painful, vision-threatening. Treat within hours to save vision; treat the other eye prophylactically if primary glaucoma is confirmed. Merck Veterinary Manual

Evidence-based treatments (acute + maintenance)

• IOP-lowering drops:

  • Carbonic anhydrase inhibitors (dorzolamide 2%, brinzolamide 1%) q8h; effective in dogs & cats (watch for stinging/rare hypokalemia in cats). Merck Veterinary Manual

  • Beta-blockers (timolol) adjunct.

  • Prostaglandin analogs (latanoprost) often first-line in dogs during acute crisis. Veterinary Vision Animal Eye Specialists+1

• Osmotic agents for emergencies: mannitol IV lowers IOP within ~15 min, effect 6–10 h (contraindications apply—heart/kidney disease, dehydration). Today’s Veterinary Practice

• Preventive therapy in the fellow eye (primary glaucoma): timolol ± other meds. Merck Veterinary Manual

• Surgical options (with ophthalmologist): laser ciliary body ablation, shunts, or enucleation for painful blind eyes.

Bottom line: If your pet shows glaucoma signs, go now—same-day emergency care can preserve comfort and vision. Today’s Veterinary Practice

🧪 Core Clinic Tests (and What They Tell You)

⚖️ Treatments Compared: What’s “Best”?

🧭 Step-by-Step At-Home Eye-Care Routine (Daily/Weekly) 🗓️

Use only products prescribed by your vet. Eye meds and order matter.

Daily (5–10 min):

1. Wash hands 🧼

2. Warm compress 2–3 min if crusty lids 🧻

3. Clean lids with vet-approved wipe/cotton + sterile saline (outer → inner) ✨

4. Med order (per vet): lubricants → pressure drops → antibiotics/antivirals → anti-inflammatories (if no ulcer). Space drops 5–10 min apart ⏱️

5. Reward calmly (treats → positive association) 🐾

Weekly:

• Inspect pupils, cornea clarity, discharge color, squinting; note changes 📒

• Launder bedding (less allergens) 🧺

Emergency rule: sudden cloudiness, severe pain, or “big hard eye” → ER now. Today’s Veterinary Practice

🧑‍⚕️ Expert Quotes (with Source Links) 🎓

“A complete ophthalmic exam—Schirmer, fluorescein, tonometry—is indicated for all conjunctivitis cases. It’s how we catch ulcers and glaucoma early.” — Today’s Veterinary Practice Today’s Veterinary Practice

“In diabetic dogs, cataracts are expected; surgery (phacoemulsification) offers the best chance to restore vision, especially when performed before severe inflammation.” — Merck Veterinary Manual & recent literature MSD Vet Manual+2Merck Veterinary Manual+2

“Acute glaucoma is a true emergency—stock mannitol and latanoprost; treat the fellow eye prophylactically when primary glaucoma is diagnosed.” — Merck Veterinary Manual & specialty guidance Merck Veterinary Manual+1

“VOs (veterinary ophthalmologists) and ACVO resources help owners recognize conditions early and find referral care.” — American College of Veterinary Ophthalmologists (ACVO) ACVO Public+1

🧩 Handy Tables & Quick Checks

A. “When to Call the Vet” ✅

• Redness + squinting > 24 h

• Thick yellow/green discharge

• Visible blue/white haze over the eye

• Pupil asymmetry, sudden blindness

• Big, hard, painful eye → ER 🚑

B. Medication Timing 💊

🧠 Frequently Asked Questions

1) How fast do treatments “work”?

• Conjunctivitis: mild bacterial/allergic cases often improve in 48–72 h; viral (cats) takes longer and may recur.

• Cataract surgery: vision often returns within days post-op (varies), with weeks of drops.

• Glaucoma crisis: drops/IV mannitol can lower IOP within minutes–hours; vision prognosis depends on how quickly pressure is controlled. Today’s Veterinary Practice

2) Can conjunctivitis be contagious to other pets?
Sometimes—viral (e.g., feline herpesvirus) and chlamydial conjunctivitis can spread between cats; typical canine bacterial conjunctivitis is often secondary to another issue.

3) Can I use human eye drops?
No. Preservatives/actives can be harmful; always use vet-prescribed meds.

4) Are cataracts the same as “nuclear sclerosis”?
No. Nuclear sclerosis is a normal aging change (bluish lens, usually retains vision). Cataracts are opaque and block light. A vet can differentiate with an exam.

5) Is surgery the only fix for cataracts?
For vision restoration, yes—phacoemulsification. Drops manage inflammation but do not dissolve cataracts. Merck Veterinary Manual

6) Which breeds get glaucoma?
Primary glaucoma occurs in many dog breeds (e.g., Cocker Spaniel, Basset Hound, Chow Chow); cats more often have secondary glaucoma. Early tonometry helps. Merck Veterinary Manual

7) What is a “normal” eye pressure?
Approx. 19 mmHg (± ~5–6) for dogs/cats by applanation tonometry; your vet interprets in context. Merck Veterinary Manual

8) Are prostaglandin drops safe for cats?
Cats often respond less to prostaglandins; carbonic anhydrase inhibitors (e.g., dorzolamide) are commonly used—your vet will choose the regimen. Merck Veterinary Manual

9) Can diet or supplements prevent cataracts?
Not reliably—especially in diabetic dogs where cataracts are highly likely. Good diabetic control and timely surgery offer best outcomes. MSD Vet Manual+1

10) What’s the best way to apply eye drops?
Wash hands, stabilize your pet’s head, rest bottle on your hand against the skull, pull lower lid to form a pocket, don’t touch the tip to the eye, and reward after. Space multiple meds 5–10 min apart.

📚 Trusted Sources & Further Reading

• Merck Veterinary Manual — Conjunctiva, lens disorders, glaucoma, diagnostics (Schirmer/tonometry). Merck Veterinary Manual+4Merck Veterinary Manual+4MSD Vet Manual+4

• Today’s Veterinary Practice — Conjunctivitis workup; acute glaucoma management. Today’s Veterinary Practice+1

• ACVO (American College of Veterinary Ophthalmologists) — Public education + referral locator. ACVO Public+1

• Merck (Owners sections) — Cataracts overview & timing of surgery. Merck Veterinary Manual

• Peer-reviewed/open access — Phacoemulsification better than topical management for diabetic cataracts. PMC

• Veterinary specialty guidance — Emergency glaucoma meds (mannitol, latanoprost, dorzolamide) stocking. Veterinary Vision Animal Eye Specialists

⚠️ Medical Disclaimer

This guide is for educational purposes only and does not replace professional veterinary care. Eye problems can worsen rapidly. If your pet shows sudden pain, cloudiness, vision loss, bulging, or severe redness/discharge, seek same-day veterinary or emergency ophthalmology care. Medication choices, dosing, and order of drops must be prescribed by your veterinarian for your individual pet.