Glaucoma is a condition in which pressure builds up inside the eye, causing pain and potentially leading to vision loss. Early diagnosis and prompt treatment is crucial to reduce the likelihood of your dog becoming permanently blind.
What happens in glaucoma?
In the front chamber of the eye, between the eye surface and the lens, there is some fluid called the aqueous humour. Normally, this fluid drains away at the same rate that it is produced. The problem in glaucoma is that the fluid is not drained away fast enough, and this causes pressure to build up.
The increased pressure can damage the delicate tissues of the retina and optic nerve at the back of the eye. Unfortunately, damage to these structures can stop visual information getting to the brain and this means glaucoma can cause blindness.
What are the different types of glaucoma?
In dogs, glaucoma can be either primary (inherited) or secondary (due to eye disease or injury). In cats, primary glaucoma is very rare and most cases are secondary.
Primary glaucoma is more common in certain dog breeds than others. Breeds known to be affected include:
- Hungarian Viszla
- Siberian Husky
- Chow Chow
- Beagle
- American and English Cocker Spaniel
- English and Welsh Springer Spaniel
- Basset Hound
- Petit Bassett Griffin Vendeen
- Shar Pei
- Golden Retriever
- Border Collie
Primary glaucoma tends to affect both eyes, but signs may appear in one eye before they develop in the other.
Animation illustrating primary glaucoma:
In secondary glaucoma, eye pressure builds up because of some disease or injury inhibiting fluid drainage within the eye.
Potential causes include:
- Inflammation of the eye (uveitis)
- Injury to the eye
- Dislocation of the lens or damage to the lens
- A tumour
Animation illustrating a secondary glaucoma:
While some causes like trauma and lens dislocation make glaucoma develop very suddenly (acute glaucoma), other conditions like tumours result in the pressure building up over a longer period (chronic glaucoma).
What are the symptoms of glaucoma?
Glaucoma can cause the following signs:
- A bluish or hazy appearance to the cornea
- More pronounced blood vessels in the white of the eye
- A dilated pupil in the affected eye
- Watery discharge from the eye
- Loss of vision
- Pain in the eye (animals may squint, become 'head shy' i.e. retreat from having their face touched, or rub their eye or face)
- General lethargy or lack of appetite due to pain
Image of a dog with glaucoma:
How is glaucoma diagnosed?
Your vet can diagnose glaucoma by measuring the pressure in the eye using a device called a tonometer. Depending on your pet's medical history, your vet may also advise other tests to diagnose the cause of the glaucoma and work out what treatment will be necessary. These include vision tests, a detailed examination of the eye, and potentially an ultrasound scan. In some cases, vets may advise a type of eye exam called 'gonioscopy' in which they use a special contact lens to assess fluid drainage in the eye.
What are the treatment options?
The aim of glaucoma treatment is to reduce the eye pressure by encouraging the fluid within the eye to drain normally. In general, the sooner treatment is started, the more chance your pet will have of avoiding permanent blindness. Treatment can involve surgery or medication with eye drops, and your vet will be able to advise on the best option for your pet.
If there is an underlying cause for the glaucoma, your vet may advise specific treatment for this, and they may also prescribe painkilling medication to make your pet more comfortable. Depending on your pet's symptoms, your vet may recommend referral to a veterinary eye specialist for treatment.
If you have questions and you'd like to reach out to us, you can call us directly at (925) 744-6421, or you can email us at [email protected].