Quick answer: Dry eye, or keratoconjunctivitis sicca (KCS), is what happens when the tear glands stop making enough of the watery layer of tears. The cornea dries, dulls and clouds, thick discharge builds in the corners, and the eye gets infected and ulcerated over and over. In most dogs it is the immune system attacking the tear glands, it runs in flat-faced and spaniel-type breeds, and it is confirmed by a one-minute Schirmer tear test. Lifelong cyclosporine or tacrolimus drops restore tear production in most dogs. At home, keep the face clean, protect the eyes from wind and hair, and support the oily tear layer with omega-3s.
Signs
- Thick, ropey yellow or green discharge that returns within hours of cleaning
- A dull, matte or bluish-grey cornea instead of a wet shine
- Red, inflamed conjunctiva; squinting; rubbing the face on furniture
- Recurrent conjunctivitis or corneal ulcers that respond to antibiotics and then come back
- Over months, brown pigment and blood vessels creeping across the cornea, which is the eye's attempt to protect itself and which itself blocks vision
Both eyes are usually affected. Because the discharge looks like an infection, dry eye is often treated as conjunctivitis several times before the tear test is done. If your dog has had more than two bouts of goopy eyes in a year, ask for the test.
Causes
Immune-mediated destruction of the tear glands is by far the most common cause and the reason the breeds below are over-represented. Others include certain sulfa drugs and anaesthetics (often temporary), nerve damage after ear or eye infections, hypothyroidism, canine distemper, and removal of the third-eyelid gland (the old treatment for cherry eye, now avoided for exactly this reason). Senior dogs produce fewer tears as glands age, which pushes borderline eyes over the line.
Breeds at risk
Cocker Spaniels, English Bulldogs, West Highland White Terriers, Pugs, Shih Tzus, Lhasa Apsos, Cavalier King Charles Spaniels, Bloodhounds, Boston Terriers, Yorkshire Terriers and Pekingese. Flat faces expose more cornea to the air, which makes any tear shortfall worse.
Diagnosis
The Schirmer tear test is a strip of calibrated paper tucked into the lower eyelid for sixty seconds. Fifteen millimetres of wetting or more is normal, under ten confirms KCS, and the range between is borderline and worth rechecking. The vet will also stain the cornea to check for ulcers and look for the pigment and vessels of chronic disease.
Treatment
- Cyclosporine or tacrolimus drops or ointment, usually twice a day for life. They calm the immune attack and restart tear production in most dogs, more reliably the earlier they are started. Expect four to eight weeks before the full effect.
- Artificial tears in the meantime and as a top-up on dry days.
- Antibiotic drops for active infection or ulcers.
- Parotid duct transposition, a surgery that reroutes a saliva duct to the eye, for the minority of dogs who do not respond to drops.
Home support
- Keep the face clean. Warm water on a soft cloth, corners of the eyes, morning and evening. Sterile eye wipes make it easier.
- Trim hair around the eyes so it does not wick tears away or scratch the cornea.
- Protect from wind and dust: no head out of the car window, dog goggles for beach and bike days if your dog tolerates them.
- Humidify the room your dog sleeps in during heating season.
- Support the oily tear layer. Omega-3 fatty acids improve the quality of the oil the eyelid glands secrete, which slows evaporation of whatever tears the dog makes. Human dry-eye trials report symptom improvement with supplementation; in dogs it is a sensible adjunct, not a replacement for cyclosporine. OcuLabs Vision Support Bites deliver 100 mg of algal DHA per two-chew serving alongside lutein, astaxanthin and beta-carotene for the retina. Read omega-3 DHA for dogs' eyes for how much matters.
Dry eye is one of seven reasons a dog's eye can look cloudy; for the rest, read why are my dog's eyes cloudy?
Frequently asked questions
What does dry eye look like in a dog?
Thick discharge that keeps coming back, a dull or cloudy cornea, red conjunctiva, squinting, and recurring conjunctivitis or ulcers, usually in both eyes.
How is it diagnosed?
A one-minute Schirmer tear test. Fifteen millimetres or more is normal; under ten confirms KCS.
Can it be cured?
Usually managed for life with cyclosporine or tacrolimus drops, which restore tear production in most dogs when started early.
Which breeds get it?
Cocker Spaniels, English Bulldogs, Westies, Pugs, Shih Tzus, Lhasa Apsos, Cavaliers, Bloodhounds, Boston Terriers and Yorkies among others.
Do omega-3s help?
They support the oily tear layer and are a sensible addition around prescription treatment, not a replacement for it.
This article is general information for dog parents and is not veterinary advice. OcuLabs products are nutritional supplements and are not intended to diagnose, treat, cure or prevent any disease.