Conjunctivitis in Dogs

Overview

Dogs get many of the same eye problems as human but many owners don’t know what they can safely do to help at home. Some products can cause serious, if not permanent, damage to an eye or interact with your dog’s other medications so it is important to know how these eye problems can be managed.
Your dog’s eyesight is valuable and nature protects the eye from dust and bacteria by a membrane called the conjunctiva which protects the sensitive eye. Conjunctivitis can affect one eye or both. Usually if it affects either it is caused by an infection from a virus or bacteria, but environmental irritants such as dust, or allergens can be other causes. If there is a discharge present, for example mucous or a pus-filled fluid, your veterinarian may need to prescribe topical antibiotics to help clear the condition.

Conjunctivitis also known as pink eye means inflammation (swelling) of the conjunctiva and can be caused by many different conditions. The conjunctiva is a very thin layer of tissue that covers the inside of the eyelid and runs across the front of the eye. Conjunctivitis causes red, itchy, weepy eyes.
We all know that conjunctival redness, or hyperemia, has many causes. Not all redness is cause for alarm, however, as it can result simply from anxiety or excitement. That being said, conjunctival hyperemia can also indicate something more serious, such as glaucoma or uveitis. Therefore, any persistent conjunctival hyperemia, especially when combined with discomfort or vision changes, should be investigated. As causes and treatments vary, a systematic approach to conjunctival hyperemia is imperative.

Major causes of conjunctivitis in dogs

There are a number of things that can cause conjunctivitis in dogs and your vet will need to investigate to establish which is to blame. Potential causes can include:

• Foreign bodies such as a grass seed or grit
• An allergy
• An injury
• Bites in the eye area
• Dry eye (caused by a lack of tears)
• Eye diseases, such as glaucoma
• A bacterial infection (normally causes green or yellow discharge)
• A viral infection, such as canine herpes or canine distemper
• Parasites, such as eye worm

Infections as the cause of conjunctivitis in dogs

Dogs can get conjunctivitis from specific viral, bacterial or parasitic infections limited to the eyes. However, the condition could also be a symptom of a generalized infection most often a virus. Just think how your eyes become and inflamed when you have a cold or flu.
There are a number of viruses that could be to blame, commonly the canine herpes virus is the culprit. Or even canine distemper.
Another possible cause is parasitic infections. One example of this is leishmaniasis which can be lethal if it attacks the internal organs and is left untreated. If the parasite attacks the mucosa (such as the conjunctiva) it can leave permanent scars. Leishmaniosis is present in tropical and subtropical regions and can be passed on to humans.

Symptoms of conjunctivitis in dogs

Some basic symptoms of conjunctivitis in dogs may include;

• Red, swollen and moist-looking eyes
• Your dog may blink a lot or squint his eyes
• You may notice accompanying symptoms such as sneezing, and nasal discharge
• Redness to the delicate eye membrane caused by the reaction of the eye to the irritant
• Your dog may paw a lot at his eyes or around the area
• Behavioral changes may be noticeable and he may become quiet, withdrawn, and sad looking
• You may notice a discharge from the eyes such as mucus or pus

How is conjunctivitis diagnosed?

The main goal of diagnosis is to determine if the conjunctivitis is a primary or secondary problem, if there is additional disease or damage to the eye, if the condition is allergic, or if it involves the tissues of the eye itself (sclera). In order to differentiate many of these conditions, a complete and detailed ophthalmic examination must be performed. This will include detailed examination of the surrounding eye structures (eyelids, eyelashes, tear ducts, third eyelid, etc.), tear production tests (Schirmer tear production test), corneal stain tests to ensure that the cornea is not damaged, and measurement of intraocular pressure to rule out glaucoma or uveitis.
Additional tests and procedures that may be performed include nasolacrimal duct flushing, bacterial culture and sensitivity tests, conjunctival cytology or biopsy, and allergy testing.

Treatment for conjunctivitis in dogs

The best treatment for your dog’s conjunctivitis will depend upon the underlying cause of the condition. Following a thorough eye examination your vet will determine the cause and the best treatment for your dog.
In cases where bacterial infection is causing your dog’s conjunctivitis, antibiotics and eye drops are typically prescribed. If allergies are the suspected cause your vet may prescribe an antihistamine to help make your dog’s eyes more comfortable, or if there is a foreign body irritating your dog’s eye your vet will remove it while your dog is under sedation or local anesthetic.
Some dogs suffer from conjunctivitis caused by a blocked tear duct in which case surgery followed by eye drops and antibiotics will be required.

If your dog is persistently pawing at their eyes while being treated it may be necessary to have them wear a cone or Elizabethan collar to prevent rubbing and allow the eye to heal
Preventing conjunctivitis in dogs
Firstly, ensure that your pup gets all the routine vaccinations. This will protect them from the serious viral infections that are spread through contact with other dogs.
For the same reason its a good idea to contain your dog in your yard, and to neuter your pooch (if they are not specifically for breeding).
Keep the fur around their eyes trimmed if your dog has long hair. Regular grooming will help prevent eye irritation caused by hair, and prevent foreign bodies that get stuck in their coat from ending up in their eyes.
If your dog suffers from conjunctivitis frequently for example as a result of allergies or dry eye, make sure that you give the treatment regularly as prescribed.
Also inspect your dogs eyes from time-to-time to pick up on problems as soon as they arise.