Dry eye in dogs and cats: signs and ongoing care

You wipe away thick discharge in the morning, and a few hours later it is back. The eye looks red and dull, and your pet keeps blinking or trying to rub it. This can happen with dry eye, but it also occurs with problems that threaten the cornea. Do not wait two days for an examination.

A closed, red or cloudy eye needs prompt care

The medical name for dry eye is keratoconjunctivitis sicca, or KCS. Familiar signs include sticky discharge, redness and a dull ocular surface. A pet may also blink too often, keep the eye partly closed or rub the face. These behaviours indicate discomfort even if the animal is still eating and playing.

The American College of Veterinary Ophthalmologists advises immediate veterinary care for signs of ocular discomfort, including squinting, redness and rubbing. There is a good reason for the urgency: a corneal ulcer can look similar and may deteriorate quickly.

Seek care promptly if your pet keeps an eye closed, tries to rub it, has a blue, white or cloudy cornea, develops new discharge, has a visible wound or trauma, or seems to have a sudden change in vision. Preventing rubbing may limit further injury on the way to the clinic, but it does not replace an examination.

A small, old crust at the corner of an otherwise comfortable, clear eye can be recorded and compared with that animal’s usual appearance. If the discharge returns, changes colour or comes with discomfort, treat it as an eye problem. The guide to what is normal for your own pet can help you establish a baseline without turning observation into a diagnosis.

What is missing in dry eye and why discharge develops

Tears form a film over the cornea. This film lubricates the surface, delivers nutrients and helps clear debris and infectious agents. It contains aqueous, lipid and mucous components. An eye can therefore have too little tear volume, or it can produce an unstable film that breaks up or evaporates too soon.

In quantitative dry eye, the lacrimal and third eyelid glands do not supply enough of the watery component. The cornea loses its smooth covering and mucus becomes concentrated, which helps explain the thick discharge. In qualitative dry eye, the measured quantity may seem acceptable while the composition or stability of the tear film is abnormal. The ACVO explains that tear film break-up time can support the diagnosis when signs persist despite apparently normal tear quantity.

Without adequate protection, the conjunctiva becomes inflamed and the cornea may ulcerate. With chronic disease, blood vessels, pigment and scar tissue can spread across a surface that should be transparent. Vision may be restricted, and an infected ulcer can put the eye itself at risk.

Yellow or green discharge does not prove that the problem is a simple infection. The MSD Veterinary Manual lists mucopurulent discharge, vascularisation, pigmentation, fibrosis and ulceration among possible features of KCS. Choosing drops from the colour alone can delay the correct diagnosis.

Dry eye does not behave the same way in dogs and cats

Classic aqueous-deficient KCS is much more common in dogs. The leading canine cause is immune-mediated inflammation that damages the tear glands. Any breed can be affected, but the ACVO lists Cavalier King Charles Spaniels, English Bulldogs, Lhasa Apsos, Pugs, Shih Tzus and West Highland White Terriers among predisposed breeds.

Quantitative KCS is rare in cats. Ocular surface disease and tear deficiency can occur together, including in cats with changes linked to feline herpesvirus, but the relationship is less clearly defined than canine KCS. A case series from three veterinary centres found only ten cats that met strict criteria for repeatedly low tear production. The authors recommend tear film assessment in cats with ocular surface disease without assuming that every case is the feline version of canine KCS.

Point of comparison	Dogs	Cats
Frequency of quantitative KCS	Common	Rare
Frequent context	Immune-mediated tear gland inflammation; neurological, infectious, congenital and medication-related causes also occur	May accompany conjunctivitis, keratitis, scarring and changes associated with feline herpesvirus
Interpreting the test	Canine reference values are considered alongside signs and the eye examination	Feline references and clinical context are needed; a single number should not be read using the canine scale
Care plan	Tear-stimulating treatment is often ongoing and, in many cases, lifelong	Depends on the cause, concurrent eye disease and response at follow-up

Short-faced animals need additional attention, but predisposition is not a diagnosis. More exposed eyes, incomplete eyelid closure, hairs touching the cornea and inefficient blinking can worsen dryness or cause similar surface disease. The ACVO recommends at least an annual eye examination for brachycephalic pets and immediate care for redness, rubbing, squinting or cloudiness.

Diagnosis measures tears and examines the cornea

The Schirmer tear test uses a strip of special paper placed inside the lower eyelid for one minute. It measures the aqueous part of the tear film in millimetres of wetting per minute. The test should be performed before anything is put into the eye because drops and handling can alter the result.

No single number settles every case. Species, signs, surface appearance, current medication and differences between the two eyes all affect interpretation. This matters even more in cats. In the feline case series cited above, a low value had to be documented at two or more visits for a cat to be included.

The veterinarian combines the Schirmer test with magnified inspection of the cornea and conjunctiva. Fluorescein adheres where the corneal epithelium has lost cells and helps reveal ulcers. According to the MSD professional manual, this dye can also be used to assess tear film stability and drainage through the nasolacrimal duct. Tear film break-up time, other stains, intraocular pressure and tests directed at an underlying cause may complete the assessment.

This combination avoids two common mistakes. One is calling every discharge conjunctivitis. The other is ruling out dry eye because one measurement was above a cut-off found online. Diagnosis describes tear quantity, tear quality and any damage already present, rather than only the wet length on a paper strip.

Treatment protects the cornea and depends on consistency

The plan may combine medicines that stimulate tear production with lubricants that replace part of the tear film. The veterinarian also treats an ulcer, infection, inflammation, eyelid problem or underlying disease when present. In dogs with immune-mediated KCS, ophthalmic cyclosporine or another immunomodulator may be prescribed. The drug, strength and frequency must be chosen for the individual patient.

Response is seldom immediate. The MSD Veterinary Manual indicates that response to tear stimulants is reassessed over weeks to months. An improvement in discharge or shine is therefore not a reason to stop treatment. Many dogs require daily lifelong care. In cats, the team needs to follow the associated cause and response rather than assuming the outcome from canine data.

Never reuse human eye drops, an antibiotic or an old bottle without checking with the veterinarian. Some steroid-containing drops are considered only after an ulcer has been ruled out. A product with a similar name that was made for the skin must not be used in the eye.

Severe canine cases that do not respond to medical treatment may be referred to a veterinary ophthalmologist to discuss surgery. This is an exception considered after confirming the diagnosis, reviewing how medication is given and assessing remaining gland function.

A simple routine prevents quiet treatment gaps

Ongoing care works better when it fits the household routine. A well-recorded week also gives the veterinarian more useful information than the vague impression that the eye “looked better”. Use this list only after receiving the prescription and an application demonstration:

• Tick off every application on your phone or on a visible sheet.
• Use each bottle in the prescribed eye and at the prescribed time. Ask the team which comes first when there is more than one product.
• Do not touch the bottle tip to the eye, eyelashes, fingers or another surface.
• Notice whether discharge returns before the next application and whether your pet squints.
• Request refills before medicine runs out and attend follow-up visits even when the eye looks clean.

If the team recommends cleaning, remove only external discharge with clean, damp material. Do not rub the cornea or force the eyelids. Cleaning clears visible buildup, but it does not replace the tear film or stimulate the gland by itself.

Avoid direct wind on the face, including a powerful fan or a head outside the car window. With brachycephalic pets, check whether the eyelids close fully during sleep and report any area that remains exposed. Do not trim hair close to the eye unless you can do so safely.

Photograph both eyes in the same light when you notice a change, without using flash close to the face. Record when the discharge returned, which product was given and whether the animal tried to rub. The article on what to note before the vet visit helps you build a short timeline. If the eye worsens, use the clinic’s contact plan or the guidance for the first hours of a pet emergency.

Frequently asked questions

Is dry eye the same as conjunctivitis?

No. Dry eye inflames the conjunctiva and can look like conjunctivitis, but redness and discharge have other causes. Tear testing and a corneal examination help separate them.

If the discharge is green, are antibiotics enough?

No. Discharge can become thick because the watery part of the tears is missing, and a corneal ulcer may be present. Treatment needs to start with an examination, not the colour.

Can I wait two days to see whether it improves?

Not if there is squinting, pain, rubbing, redness, cloudiness, new discharge or a change in vision. These signs justify prompt contact and assessment.

Does a normal Schirmer result rule out dry eye?

Not in every case. The test mainly measures the aqueous component. An unstable tear film or altered tear quality can require other tests.

Will every pet with dry eye need drops for life?

Many dogs with immune-mediated KCS need lifelong treatment. In cats and in neurological, medication-related or anatomical cases, the plan depends on diagnosis and follow-up. Never stop treatment without veterinary advice.

Can I clean the eye with sterile saline?

Ask the team to show you the appropriate product and technique. External cleaning may remove discharge, but it does not treat tear deficiency or replace prescribed medication.

Take the ebook and a clear timeline with you

The dry eye ebook will become available on this page after registration. The download is in Brazilian Portuguese. Use it to recognise the topic and organise questions, not as a substitute for a consultation. If the eye looks painful or has changed, seek care first and bring times, photographs and the names of any products already used.

To see how Criando Elos organises prevention, warning signs and care at home, explore the available courses. Good information shortens the route to appropriate care, but the eye examination is what shows whether the cornea is safe.