Dry Eye in Dogs: A Vet-Reviewed Guide

At a glance

• Dry eye, clinically known as keratoconjunctivitis sicca or KCS, is a reduction in tear production that leaves the surface of the eye inadequately lubricated
• The most common cause is immune-mediated: the dog's own immune system gradually damages the tear-producing glands
• Certain breeds are considerably more prone to it, including West Highland White Terriers, Cavalier King Charles Spaniels, Shih Tzus, Pugs and English Bulldogs
• Symptoms include redness, thick or stringy discharge, excessive blinking, squinting and a dull-looking eye surface
• Dry eye is diagnosed with a simple in-practice test and is treatable, but usually requires lifelong medication

Dry eye is one of the more common eye conditions vets see in dogs, and one of the easier ones to miss in its early stages. It often begins subtly, with slightly more discharge than usual or a bit of squinting, and because it typically develops gradually, owners can adjust to it without registering that something is wrong.

This is a guide to what the condition is, what causes it, what to look for, and when it needs a vet rather than a wait-and-see approach.

What is dry eye in dogs?

Dry eye is a reduction in the quantity or quality of tears, leaving the surface of the eye without adequate lubrication. Its clinical name is keratoconjunctivitis sicca, usually shortened to KCS.

Tears do more than keep the eye wet. They carry oxygen and nutrients to the cornea, which has no blood supply of its own, and they flush away debris and bacteria. When tear production falls, the cornea is left exposed. Over time that causes inflammation, discomfort, and changes to the corneal surface itself, which can become cloudy, pigmented or ulcerated.

Untreated, dry eye can lead to permanent damage to the cornea and, in severe cases, loss of vision. This is why it is treated as a condition needing prompt veterinary attention rather than something to monitor at home.

What are the symptoms of dry eye in dogs?

The signs vary depending on how advanced the condition is. Early on they can be easy to attribute to something else.

Common signs include:

• Thick, sticky or stringy discharge, often yellow-green, which returns quickly after being cleaned away
• Redness of the eye and the surrounding tissue
• Excessive blinking, or holding the eye partially closed
• Pawing or rubbing at the eye, or rubbing the face along furniture and carpet
• A dull or hazy appearance to the eye surface rather than a clear, wet shine
• Sensitivity to bright light
• Repeated bouts of conjunctivitis that improve with treatment and then return
• Visible discomfort when the eye area is touched

The discharge is often the sign owners notice first. Because tears are not flushing the eye, mucus accumulates instead, and it tends to reappear within hours of being wiped away.

One pattern is worth knowing. Dry eye usually develops gradually, and while it commonly affects both eyes, one is often worse than the other to begin with. Sudden onset, or both eyes becoming affected at the same time, warrants prompt veterinary assessment.

What causes dry eye in dogs?

There are several distinct causes, and identifying which one applies matters because it shapes treatment.

Immune-mediated damage is the most common cause by a considerable margin. The dog's immune system mistakenly targets the lacrimal glands, progressively reducing their ability to produce tears. This process is gradual and is usually the explanation in breeds predisposed to the condition.

Medication can be a factor. Sulfonamide antibiotics are the best-documented example, and some non-steroidal anti-inflammatories have also been implicated. This form is sometimes reversible if the drug is identified and stopped, which is one reason it is worth telling your vet everything your dog is taking. While tear production may recover after the responsible drug is withdrawn, in many cases KCS persists permanently.

Hypothyroidism and other endocrine conditions are associated with reduced tear production. Dogs diagnosed with an underactive thyroid are often worth testing for dry eye.

Nerve damage affecting the supply to the tear glands can reduce or stop tear production. This may follow trauma, ear disease or surgery, and often presents alongside other signs such as a dry nostril on the same side.

Injury or infection. Trauma to the eye or the surrounding tissue can damage the glands or their ducts. Canine distemper virus can also damage tear-producing tissue.

Congenital and breed-related factors. Some dogs are born with underdeveloped tear glands. More commonly, certain breeds carry a genetic predisposition to the immune-mediated form.

When should I take my dog to the vet?

Any suspected dry eye is a reason to book an appointment rather than wait. The condition is progressive, and the damage to the cornea that occurs while it goes untreated is not always fully reversible.

Contact your vet promptly if you notice persistent discharge, redness, squinting or a dull-looking eye. Contact them urgently, the same day, if your dog seems to be in pain, if the eye surface looks cloudy or has a visible mark or dip in it, if the eye is being held shut, or if you think vision may be affected.

Do not use human eye drops, leftover medication from a previous condition, or another pet's prescription. Some human preparations are unsuitable for dogs, and steroid drops in particular can cause serious harm if the cornea is ulcerated. Cleaning discharge away gently with cooled boiled water and a clean pad is reasonable while you wait for an appointment.

How is dry eye diagnosed?

The main test is the Schirmer tear test. A small calibrated paper strip is held against the inside of the lower eyelid for a minute, and the distance the tears travel along it is measured. It is quick, does not require sedation, and provides an immediate measurement of tear production in the consulting room.

A vet will usually also examine the cornea with a fluorescein stain, which reveals ulcers or scratches that are not visible otherwise, and may check for underlying causes such as thyroid disease depending on what they find.

How is dry eye treated?

Treatment has two goals: stimulating the dog's own tear production, and protecting the eye surface while that takes effect.

The mainstay for the immune-mediated form is a topical immunosuppressant, usually ciclosporin and sometimes tacrolimus, applied to the eye. This reduces the immune attack on the tear glands and, in many dogs, restores a useful level of tear production over several weeks.

Alongside that, artificial tear preparations and lubricating ointments protect the cornea. Antibiotics may be needed if there is secondary infection, and a mucolytic can help break down thick discharge. Where medical management is not sufficient, a surgical option exists that redirects a salivary duct to moisten the eye, though this is uncommon and reserved for cases that do not respond.

Most dogs do well. The important point is that treatment is usually lifelong, because tear production tends to fall again if medication stops. Consistent treatment and veterinary follow-up are therefore important.

FAQs

Is dry eye in dogs painful?

Yes. Without adequate tears the cornea becomes inflamed and can develop ulcers, which are painful. Dogs often show this through squinting, pawing at the face, or reluctance to be touched around the head rather than through obvious distress.

Can dry eye in dogs be cured?

It can usually be controlled rather than cured. Most dogs respond well to treatment, but tear production tends to decline again if medication is stopped, so treatment is typically continued for life. The exception is dry eye caused by a medication, which in some cases may resolve once that drug is stopped, although this is not guaranteed.

Can dry eye cause blindness in dogs?

It can if left untreated. Prolonged lack of lubrication damages the cornea, which can scar, become pigmented or ulcerate, and in severe cases this can permanently affect vision. Treated promptly, that outcome is uncommon.

How is dry eye in dogs diagnosed?

With a Schirmer tear test, in which a calibrated paper strip is placed against the lower eyelid for a minute to measure tear production. It is quick and requires no sedation.

Can I treat my dog's dry eye at home?

No. Dry eye needs prescription treatment and an accurate diagnosis, because the appropriate medication depends on the cause. Human eye drops should not be used (unless your vet advised you to), and steroid drops can cause serious harm if the cornea is ulcerated. Gently cleaning discharge with cooled boiled water is reasonable while waiting for an appointment.

Which dogs are most likely to get dry eye?

West Highland White Terriers, Cavalier King Charles Spaniels, English Cocker Spaniels, Shih Tzus, Pugs, English Bulldogs and several other breeds are diagnosed with it more often. Middle-aged and older dogs are affected more frequently than young ones.