What is Glaucoma in Cats and Dogs
Glaucoma is a serious eye condition in both cats and dogs where the intraocular pressure (IOP) inside the eye becomes abnormally high. This pressure damages the optic nerve and can lead to permanent blindness if not treated promptly.
What causes glaucoma in cats and dogs
Inside the eye, fluid called aqueous humor is constantly produced and drained to maintain pressure. Glaucoma occurs when this drainage is blocked, causing a buildup of fluid and pressure.
There are two main types:
Primary glaucoma is inherited, and more common in dogs.
Secondary glaucoma caused by another eye disease (e.g., uveitis - inflammation within the eye and common in cats -, trauma, lens luxation, tumour).
Written by Dr. Mariella Roberts, Veterinary Surgeon, Animal Trust Vets CIC | Published October 2025 | Review date October 2028 | This advice is for UK pets only and is not a replacement for seeing a vet
Symptoms of glaucoma in cats and dogs
- Eye pain: your pet may squint or show signs of discomfort.
- Redness: the white part of the eye can appear red and engorged.
- Cloudy or bluish cornea: the transparent front of the eye can become opaque or tinted blue.
- Watery discharge: a watery discharge from the affected eye may be present.
- Lethargy: your pet might become depressed, lose their appetite, or seem unresponsive.
- Enlarged eyeball: the eye may visibly swell.
When to contact your vet
Glaucoma is an emergency, and your pet should immediately have veterinary attention if any of the above symptoms are present, particularly if his/ her eye is cloudy or bloodshot.
Diagnosis
Your vet will perform:
- An eye exam (look at the optic nerve, retina and cornea)
- Identify underlying causes (especially in cats)
- Measure intraocular pressure (tonometry)
Acute glaucoma is a medical emergency, and in some cases, your pet may need to be referred to an eye specialist (ophthalmologist).
Treatment of glaucoma in cats and dogs
Emergency treatment (Acute Glaucoma)
- Medications to reduce pressure
- Pain management
- Treatment of any underlying cause(s) (especially in secondary glaucoma)
Long-term management
- Eye drops (to reduce fluid production or increase outflow)
- Anti-inflammatory medications
- In cats managing the underlying problem often can control glaucoma
Surgery may be needed if your pet does not respond to the medical treatment or he/she is in a lot of pain and the most common procedure is enucleation (removing the eye).
Prevention of glaucoma in cats and dogs
- Regular veterinary eye exams, especially for predisposed breeds
- Avoiding eye trauma
- Promoting good overall health through proper nutrition and avoiding neck pressure from collars
- Treating underlying eye conditions promptly to prevent secondary glaucoma
For cats, early detection and treatment of eye conditions like tumours or inflammation are vital, as these often lead to secondary glaucoma.
Outlook
The outlook for cats and dogs with glaucoma is generally guarded, as it is a painful, progressive condition that is not curable but must be managed with lifelong medication and regular veterinary care to control eye pressure. In some cases that do not respond to medical treatment or if blindness has developed, removal of the eye may be recommended to relieve the pain and discomfort.