Eyes

One of the commoner reasons we see dogs, cats and rabbits is because they have problems affecting their eyes or the structures associated with them.

Our pets have vision far superior to our but only see in pastel shades (and very few blues) compared to us. Of their senses sight is really important although they are often less bothered emotionally by us should they get reduced sight.

Sometimes eyes can be damaged by disease, cancer or trauma to the extent that we need to remove one. This is something that sounds very scary to the human owner but poses far less of a problem to the pet, provided they are left with one good eye. Cosmetics are less of an issue to animals!

Below is a range of eye conditions with some notes that you may find interesting and useful. Feel free to contact us if you have any queries about your pet’s eyes.

Eye Map

The diagram shows some basic eye anatomy in cross section.

Cataracts

Sometimes we see hereditary cataracts in young animals but by and large cataract formation is a progressive problem in older pets. As the lens ages.so it’s structure changes and it begins to reflect rather than transmit light through to the retina. Eventually it can become opaque.

In the early stages lens degeneration may just affect close up vision as the lens loses the ability to change shape. Late,r sight can become a lot worse. Whether or not we consider cataract surgery depends partly on how much of a problem the pet is experiencing. We know some pets that are completely blind but have a great life quality, still going for regular walks etc. Others can become very nervous, even in the house where they generally can still find their way about from memory.

Cataracts can sometimes occur secondary to other diseases like diabetes mellitus or Cushings disease so you should come and see the Veterinary Surgeon if you think there is a problem.

Conjunctivitis

Can be painful and is inflammation of the lining of the eyelids and superficial layer of the eyeball. It can be caused by infection (e.g. cat flu viruses), trauma and infection (cat scratch and secondary bacterial infection), irritation (e.g. dust), allergy and sometimes infiltrative cancers like lymphoma.

We usually always need to see patients with conjunctivitis to ensure the conjunctiva isn’t penetrated exposing the cornea underneath. We also need to take a good look, maybe collect samples (swabs), make a diagnosis and then decide the most appropriate treatment.

Kerato-Conjunctivitis Sicca (KCS or Dry Eye)

This is a special type of conjunctivitis caused by disease (usually immune mediated) where the pet (usually dog, although we do see it in other species) stops making sufficient tears to keep the corneal surface healthy. The conjunctiva and cornea become inflammed. The cornea will eventually degenerate and pigmentation arises. Sometimes the cornea can become weak and burst.

It is east to diagnosis with a simple test – the Schirmer Tear Test – which measures tear production over a minute.

Check your dogs eyes. KCS is really under-diagnosed and when we do see them it is often later in the disease process. It is an easily treatable condition although usually in means you have to apply eye drops once a day for life. Please contact us if you have any doubts.

Corneal Ulcers

These are emergencies. Injuries or infections of the conjunctiva can involve exposure of the underlying cornea (see here where the ulcer takes up a special fluorescent dye). The corneal ulcer can deepen and the eye can burst.

Sometimes we see corneal foreign bodies (bits of claw, twig or sand / shrapnel).

Fortunately the ulcer and overlying conjunctiva can heal quickly if treatment is sought early enough. In some cases we will use the pets own serum to make eye drops with to treat the ulcer. Sometimes we will apply a bandage lens and may need to remove damaged cornea to create a healthy, healing bed with a good blood supply. In more serious cases we may suture a conjunctival graft over the deficit to allow it to heal.

Glaucoma

This is a painful condition where the eye doesn’t drain fluid properly and the pressure inside increases, eventually putting some much pressure on the retinal blood vessels that the pet can go blind. Sometimes it just happens for no obvious reason, sometimes it can be caused by obstruction of drainage by tumours inside the eye for example.

We use a special instrument called a tonometer to measure the Intra ocular pressure and in the simplest cases glaucoma can be successfully treated with eye drops.

We have only covered some of the more common eye problems here.There are a range of hereditary and congenital problems that can occur and it is important that we examine your new kitten or puppy as soon as possible to check that their eyes are healthy.

The health of the eyes can tell us a lot about disease elsewhere in your pet. For example uveitis (which includes inflammation of the coloured part of the eye, the iris) can be a symptom of Feline Infectious Peritonitis in cats. Pale ocular membranes can be caused by poor circulation or anaemia, yellow tinged membranes may be a symptom of liver disease and blue tinged membranes can arise because of heart disease.

Lots of changes can occur in the eyes that are nothing to worry about, e.g pigmentation of the sclera (white of the eyes) can be normal, other pigments may be the beginnings of something more sinister. There are a whole range of conditions that can affect the eyelids.

Rabbits have their own set of peculiar problems – from tear overflow caused by blocked nasolacrimal ducts, in turn caused by dental disease to parasites living inside the eyeball.

Eyes are so important that if you notice any changes, no matter how small, you should come and see the Veterinary Surgeon. We will usually fit most acute eye problems in as an emergency.