A cat with a herpetic ulcer, a dog with glaucoma, a horse with a wound to the surface of the cornea, they’ll all have some combination of a red eye, pain (e.g., holding the eye partially shut), and drainage.
What this means for owners is that when your pet has these symptoms, your veterinarian really can’t tell you what is going on without performing an exam (we’re really not just trying to get you to come in so we can charge for our time). To make matters worse, we also can’t determine over the phone how serious the situation might be. Do I need to stay after hours or send you to the emergency clinic, or can you wait for an appointment that’s at a more convenient time for everyone? Hard to say.
I perform a little over-the-phone triage on eye problems. If it’s a chronic but stable issue, we can probably wait for the next appointment slot that works for you, but if this is a problem that you just noticed or something that you’ve been ignoring and is now getting worse … get your pet in ASAP no matter the inconvenience or extra cost that might be involved.
I don’t mess around with red, “angry” eyes for two very important reasons:
Under most circumstances, an ophthalmologic exam and a few relatively quick and cheap tests (e.g., a Schirmer tear test measuring tear production, a corneal stain to look for wounds/ulcers on the surface of the eye, and a check of eye pressure) will produce a diagnosis and treatment plan. There really is no benefit to taking a wait and see approach when it comes to eye problems in animals, and in people too, I suspect.
Dr. Jennifer Coates writing for PetMD