Eye discharge in cats and dogs

This article is written by Pet Circle veterinarian, Dr Angie Armstrong BVSc

Eye discharge can refer to any fluid that comes from the eye and is commonly seen in both cats and dogs. It can become a problem when it is excessive in nature, abnormal for the pet or accompanied by other signs. It can appear suddenly with a painful and red eye, or it can be more chronic in nature and not seem to bother the pet. Either way it is important to get it assessed by a vet to determine the possible cause and establish what treatments are required.

Contents:

Types of Eye Discharge

Conditions that may Cause Eye Discharge

1. Eye Ulcers
2. Tear Staining Syndrome
3. Eyelash and Eyelid Abnormalities
4. Conjunctivitis
5. Dry Eye

Treatment of Eye Discharge

Tips for Applying Eye Drops or Ointment

Further Reading

Types of Eye Discharge

Watery discharge This can indicate serious eye disease, usually see a half-closed watery eye and may see increased blinking due to pain. This could be due to an eye ulcer (scratch on the eyeball), a foreign body in the eye, or inner eye disease (such as uveitis or glaucoma).May also be seen with conjunctivitis, environmental irritant (such as wind, sun and allergies) or disorders of eyelashes and eyelids.

Mucoid discharge This discharge is often green or yellow in colour. It may be due to a foreign body, chronic disease, infection (such as conjunctivitis) or dry eye (a disease that causes reduced tear production in dogs).

Conditions that May Cause Eye Discharge

1. Eye Ulcers

Dogs and cats can both develop eye ulcers. An eye ulcer is essentially a wound or scrape to the surface of the eye. Common causes include rough contact with thorns, plants or bushes, scratches from other animals, self trauma (from rubbing), chemical irritation (such as shampoo when bathing) or foreign body injury such as some plant material getting stuck under the eyelid. It is important if your dog or cat is showing signs of an eye ulcer to take them straight to the vet for an examination.

Treatment usually involves pain relief, antibiotic drops or ointment, and an elizabethan collar which can be useful to prevent your dog or cat from rubbing their eye.

2. Tear Staining Syndrome

Often seen in light coated animals like Maltese dogs and Persian cats. This can occur due to impaired tear drainage from a blocked tear duct or where the tear duct itself in not formed properly. You may notice red/brown staining of the hair below the eyes, by a compound in the tears. There are some products to clean the tearing and prevent staining, and there is an option for flushing the duct under anaesthetic if it is just blocked. For more information see our article on Tear stains in cats and dogs.

3. Eyelash and Eyelid Abnormalities

Entropion is inversion of the eyelid margin, so basically the eyelid rolls in and rubs on the eyeball and this may cause irritation by the eyelashes rubbing on the eyes or lids that don’t fully close over the eyes. Ectropion is the eversion of the eyelid margin so the eyelid rolls outwards.Eyelash disorders: Distichia where the eyelash grows from the eyelid margin rather than the eyelid skin and can slightly rub on the eyeball. Ectopic cilia are usually more significant as these short eyelashes rub directly on the eyeball and can cause discomfort and even corneal ulceration in young dogs.

4. Conjunctivitis

Conjunctivitis is inflammation of the conjunctiva, which is a tissue that makes up part of the eye and eyelid. Causes of conjunctivitis include:

Anatomical factors such as eyelid and eyelash abnormalities

Environmental causes include irritation from dust,wind, smoke, weeds and pollens and even irritating shampoos or medications near the eye

Infectious causes also play a frequent causant role specifically bacteria as well as viruses and parasites

Allergies may cause conjunctivitis either from local allergens in the grass, systemic allergies such as food allergies, and atopic dermatitis (hay fever).

Bacterial Conjunctivitis in dogs

Bacterial conjunctivitis is quite uncommon in dogs and cats. Most cases of bacterial conjunctivitis are secondary to another underlying eye disease such as; dry eye, eyelid abnormalities, and corneal ulcers that cause inflammation and subsequent bacterial infection. Treatment is usually with a topical antibiotic ointment as well as treatment of any underlying disease.

Allergic Conjunctivitis

This is seen quite commonly in the dog and often in association with atopic dermatitis (hay fever). Therefore a common finding is an itchy dog. This type of conjunctivitis is often treated with a steroid ointment.

Infectious Conjunctivitis in Cats

The most common causes are herpesvirus and chlamydia. Herpesvirus is a respiratory virus in cats. Cats who have the virus may show symptoms such as eye discharge, especially during periods of stress, such as moving house. Treatment is with viral or bacterial ointments depending on the cause of the infection. It is also important to make sure your cat is up to date with their vaccination!

5. Dry Eye

This is a disease that causes inadequate tear production and is usually a result of an immune system disorder. Tears provide lubrication to the eyes as well as removing allergens form the surface of the eyes. With dry eye, even though there is decreased tear production, the disease stimulates mucous production which is why you may notice a thick yellow/green discharge on the eyeball. Your vet can diagnose this condition by measuring the tear production in each eye. Treatment is through adding lubrication to the eyes and using medication to increase tear production, which is usually very successful.

The Best Products for Removing Tear Stains

Treatment of Eye Discharge

Treatment involves determining the cause if possible! Symptomatic care may be cleaning the eye by gently soaking off any crusty discharge and the application of sterile eye wash.

Tips for Applying Eye Drops or Ointment

Firstly clear away any discharge with a warm water soaked cotton ball

If applying eye drops, tilt your dog's head back and aim the nozzle of the drops a few cm's distance from the eyeball in case your dog moves whilst applying them

If applying ointments you can squeeze some directly onto the eye or gently pull down the eyelid creating a pocket to squeeze the ointment into

Gently close the lids together to help spread the drops and/or ointment

Further reading

Tear stains in cats and dogs

Sensitive and itchy skin in dogs

Causes of itchy skin in cats

7 tips for caring for a blind dog

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