Additional Information

What is glaucoma?

Glaucoma is a type of eye disease which occurs when the fluid produced inside the eye cannot drain properly from it. This causes a build-up of fluid and pressure within the eye to unhealthy levels. The pressure build up is not only painful but can cause blindness as it leads to damage of the retina which is required for vision.

What are the different types of glaucoma?

There are many different types of glaucoma, but they can generally be divided into inherited and non-inherited forms.

Inherited (or ‘primary’) glaucoma occurs in certain predisposed dog breeds as a result of mutations in their DNA which are passed from parent to offspring. For this reasons, certain dog breeds, should be examined or, where possible, have a DNA test before they are used for breeding.

Non-inherited (or ‘secondary’) glaucoma occurs when other diseases inside the eye lead to a problem with fluid drainage. There are many causes of secondary glaucoma including trauma, inflammation, a complication of cataract surgery and cancers of the eye.

Identifying glaucoma

Glaucoma may either be gradual or sudden onset. When the signs are gradual (e.g. increased redness and cloudiness of the eye) they are not often picked up by owners until glaucoma is very advanced. Sudden onset glaucoma is easier to spot as the pet becomes suddenly painful and the eye quickly changes appearance and becomes blind. Prolonged increases in eye pressure may lead to enlargement of the eyeball.

Diagnosing glaucoma

Diagnosis of glaucoma requires a complete eye examination and measurement of the eye’s pressure with a device called a tonometer. Often, the primary care vet, may need to seek the opinion of a specialist to aid in diagnosis and form the most appropriate treatment plan.

 Glaucoma treatment

Medical and surgical treatments are available for glaucoma but most glaucomas require long-term management. The choice of medical or surgical treatment depends on the type of glaucoma present.

It is important to decrease the pressure within the eye as quickly as possible in order to minimise damage. Drugs that can draw fluid out of the eye and others that decrease production of fluid are often prescribed. After the pressure is lowered, it must be stabilized to prevent future problems.

Dogs with a painful and blind eye as a result of glaucoma may need it to be removed to relieve pain (this procedure is called enucleation). To read more please click here

There are several types of glaucoma but, in dogs, all forms are associated with high pressure within the eye. It tends to be a painful condition and often leads to blindness despite treatment with medicines (eye drops) or surgery. Sadly, many dogs with glaucoma, need to have their eyes removed on welfare grounds to relieve them of the pain. Some types of glaucoma are inherited and occur because the fluid produced inside the eye cannot drain out. This leads to a build-up of pressure in the eye which causes pain and blindness. In the UK, inherited glaucoma is thought to affect at least 15 different dog breeds. Conservatively, at least 1000 dogs are estimated to have their eyes removed because of inherited glaucoma each year in the UK alone which is a significant welfare problem.

It was the frustrating nature of this condition which prompted our Head of Ophthalmology, James Oliver, to undertake a PhD to investigate the genetics of glaucoma in dogs.

His main aim was to develop DNA tests which breeders could use as tools to prevent puppies from being born/produced which would develop glaucoma in later life and need to have their eyes removed.

James’ PhD was only possible due to generous funding from the charity Dogs Trust and was supervised by Dr Cathryn Mellersh who runs the Kennel Club Genetics Centre at University of Cambridge (previously Animal Health Trust).

James’ research led to eight different scientific publications and was instrumental in demonstrating the cause of glaucoma in four different dog breeds. Dog breeders can now use a simple DNA test to find out if their dogs carry the faulty glaucoma genes before they are bred from. Therefore, they can prevent the faulty gene being passed on to any offspring. Eventually, through careful breeding, these faulty genes can be eliminated along with the glaucoma. These DNA tests, and many others, are offered by Cambridge University (www.cagt.co.uk).

The Ophthalmology Team at DWR continues to collaborate with the Kennel Club Genetics Centre at Cambridge and they are currently working on several exciting projects together. All of these are focussed on understanding the cause of various inherited eye diseases with the aim of developing DNA tests which can be used to eventually eliminate these causes of blindness in dogs. If you own a dog which has been diagnosed with an inherited eye disease and you would like to contribute a DNA sample for further research then please email [email protected]

During James’ PhD he examined over 1,000 dogs at various events all over the UK to assess them for inherited glaucoma. It was during one of these events that James came across Monty a delightful Basset Hound! James diagnosed Monty with a type of inherited glaucoma that had never been reported in the Bassett Hound before (primary open angle glaucoma). The discovery of Monty was quickly followed by that of other Basset Hounds with this condition. Within a few months a DNA test was developed which Basset Hound breeders could use to prevent them from unwittingly using dogs with the faulty gene for breeding. Thus, by using the DNA test properly, no more Basset Hounds need be affected by this type of glaucoma again!