Eye care for dogs

 
June 4th, 2008

Keeping your dogs eyes clean and healthy appears to be easy but dogs, just like humans, can suffer from various eye diseases. Michelle Minehan finds out the importance of recognising the signs of eye disease and gives you the know how to eye care for dogs.

Veterinary ophthalmologist Dr Mark Billson from the Veterinary Specialist Centre in Sydney spoke to Dogs Life about canine eye care, from cleaning your poochs eyes to various eye diseases common to dogs.

Cleaning eyes

Cleaning your dogs eyes is a simple task. A healthy dogs eyes should be clear, bright and free from dirt, discharge and inflammation. Unless they have an infection or medical eye problem, cleaning can be done quickly without causing your dog pain or distress.

If your dog has no underlying medical problem, said Billson, cleaning his eyes can be done simply and effectively with saline or warm water and a make-up remover cotton pad.

However, if the eyes seem to be getting worse if, for example, there’s a discharge seek medical advice, Billson advised: If the eyes are watery or have a mucopurulent discharge [containing mucus and pus] that’s recurrent or associated with redness and discomfort, then the owners should consult a vet.

Alternatively, some conditions, such as recurrent inflammation/infection of the eyelids, can present more continuous discharge, Billson said.

My recommendation for cleaning eyes is to use one-to-one baby shampoo with water, he said.

However, pet owners should seek advice from their local veterinarian first.

Easy tip for cleaning eyes

The baby shampoo should always be applied with the dogs eyelids closed. A cotton pad is best for application. Be careful not to put too much shampoo with the water as this could be too strong for your poochs eyes. After cleaning, ensure the shampoo is well rinsed with warm water to leave no soap.

Short/long-sightedness in canines

Just like humans, dogs can suffer from many different eye problems. However, its important to recognise that dogs may view the world differently from us. This means terms that we use, such as long/short-sight, may not be appropriate in considering vision in dogs.

Unlike people, vision in dogs is more geared towards identifying movement, and the ability to discern detail is not as well developed in dogs as it is in humans, Billson said.

Dogs obviously don’t do a lot of reading. Past studies suggest that dogs have trouble focusing on objects closer than 30cm and they actually use their senses to investigate very near objects.

There is evidence of some variation in vision between different breeds and indeed amongst individuals, said Billson. On average, the degree of variation appears to be relatively limited though in studies undertaken so far.

As Billson explained, its hard to compare canine eyesight to that of humans and its not exactly known the degree to which dogs suffer from long/short-sightedness. There does howe’ver appear to be a tendency towards development of short-sightedness with age.

Some breeds may be affected more by short-sightedness (medically known as myopia) than others such as German Shepherds, which appear to have a higher proportion of developing myopia.

Many different factors contribute to myopia, Billson explained. For example, if a dog has a cataract and undergoes surgery without the lens being replaced, it will have trouble focusing on close objects.

In people, advancing age affects the ability to focus on near objects and hence reading glasses are needed, he said. Its also like that with dogs. Age and other factors can all contribute to myopia.

Cataracts

A cataract is any opacity in the lens. If you look at a dog that has a cataract, an opacity is the haze that covers the lens. It represents a change in the lens fibres which might result in destruction of its normal architecture.

Instead of light passing through the lens, light is scattered so that, to an observer, there is an opacity within the eye. With this scattering, the affected eye is unable to clearly focus. The more advanced the cataract, the greater the scattering and the greater the opacity.

Unlike most tissues in the body, the lens does not a have a blood supply and relies very much on a healthy environment within the eye and the body to obtain nutrition and maintain health, Billson said. Consequently, any disruption to the environment within the eye can result in cataract formation.

There are many different causes and contributing factors to cataracts. They can even form due to an abnormality in foetal development, he said. Some dogs develop cataracts with age and some are caused as a result of eye inflammation and infection or even due to trauma or as a result of diseases elsewhere in the body, such as diabetes.

We mostly recognise an increase in cataract formation with advancing age, he said. Although the lens undergoes normal changes with age which change its appearance including a change in the type of proteins present and becoming more dehydrated these will not interfere with vision.

More severe changes and cataract development will cause vision impairment. One possible explanation put forward for this is oxidative damage through exposure to UV radiation.

Up until now the only effective treatment available for cataracts has been surgery. Just as with human cataract removal, the surgery involves removing the entire lens and is achieved using an ultrasound: a technique known as phacoemulsification.

Research is currently being undertaken to explore other techniques as well as medical management, including anti-oxidants, to try to slow cataract progression. However, explained Billson, as yet no other techniques have been proved objectively to be effective.

Blindness

Vision is a function of a normal eye. The eye acts much like a camera in capturing the image, which is then processed to the brain. Blindness can be related to a problem with the eye or with the pathway to the brain, or indeed with the brain itself, Billson said.

Just like cataracts, some causes of blindness are operable; however, some are irreversible, he added.

The retina is like the film in a camera, he said. Stimulation of the retina is the first part of vision. Therefore retinal diseases, such as detachment or degeneration, can result in blindness as the retina is unable to capture the image.

The optic nerve transmits the information from the eye to the brain, he said: If there is a disruption to this pathway, this will also result in blindness.

Disruption can be due simply to inflammation, although it can also potentially be due to a brain tumour. When brain tumours are the cause of canine blindness, other neurological signs may also be present.

If you notice any signs in your pooch, Billson said, its vital to seek medical advice as early as you can as in some cases early intervention can save or restore vision.

Caring for a blind dog

Being the owner of a blind dog can be just as stressful as it is for the dog. Billson said one of the most important things to do is to establish whether or not your dog is in pain. Pain can affect your dogs ability to cope with being blind.

Glaucoma is a condition associated with an elevated pressure inside the eye. The pressure on the eyes interior is a result of a decrease in the amount of fluid that normally drains from it.

This condition is very painful and can be associated with headaches in addition to eye pain in people, he said, and there is every reason to believe the same signs are present in dogs.

Unfortunately, its easy to misinterpret how an animal is feeling. Hearing and smell in dogs are superior to people and, in a familiar environment with an established routine, pain-free dogs will often cope extremely well.

As dogs vary from one another, owners need to take precautions in the household to minimise injury, Billson advised.

Red eyes

Many dog owners will say that at some point theyve noticed their dog with red eyes. A red eye is associated with an increase in blood flow to the conjunctiva.

The major causes of red eyes in dogs are:

  • Tear film abnormalities
  • Conjunctivitis
  • Allergy
  • Infection
  • Trauma/injury
  •  Foreign body
  •  Corneal disease
  •  Glaucoma
  • Intraocular inflammation

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