Glaucoma is common in dogs. There are two forms that are considered primary, which means that the condition is directly from a problem in the eye vs. from an illness somewhere else in the body that caused a problem in the eye.
The problem occurs when fluid that is naturally produced in the eye by the ciliary body can't pass through the pupil and out the drainage angle that is located at the front of the eye. If the holes that allow the fluid to flow are not formed correctly, your dog could be at risk for glaucoma which is a build up of fluid pressure (called IOP or intraocular pressure).
The two types of primary glaucoma are:
- Narrow angle glaucoma: abnormal narrow opening into the ciliary cleft
- Goniodysgenesis: presence of an abnormal pectinate ligament which has teeth like a comb. These "teeth" block the fluid.
Draining problems can be inherited. Medical science doesn't quite understand why glaucoma and goniodysgenesis occurs later in life vs. at birth although the obvious answer is that the drainage angle may become narrower with age.
Breeds With an Above Average Incidence of Canine Glaucoma
Many breeds of dogs are affected including:
- Cocker Spaniel
- Basset Hound
- Arctic circle breeds (Samoyed, Siberian Husky, Norwegian Elkhound)
- Terrier breeds
- Miniature Poodle
- Chow chow
- Shar pei
Symptoms of Goniodysgenesis
Symptoms of both forms of primary glaucoma include:
- Severe pain
- Sensitivity to light (photophobia)
- Winking spasms (blepharospasm)
- Eye appears to have fallen into the socket (enophthalmos)
- Raised third eyebrow
- Your dog winces when you touch his or her head
- Watery eyes
- Behavioral Change (hiding, refusal to eat)
- Red Eye
- Dilated Pupils
Your veterinarian will look for the follow clinical signs in addition to the symptoms above:
- Fluid buildup in the eye (corneal edema)
- Unresponsiveness to light
- Loss of vision
A procedure called a gonioscopy can detect changes in the drainage angle. That, combined with techniques for measuring fluid pressure in the eye, can help form the basis for a definitive diagnosis.
Treatment of Canine Goniodysgenesis
With early diagnosis and immediate treatment of canine goniodysgenesis you can avoid or reverse vision loss.
Several medications are available to help lower the pressure in the eye (intraocular pressure), but some drugs are not effective in all breeds. In this case a combination of medications will be tried.
Surgical techniques that might help are:
- Cyclocryotherapy (freezing tissue)
- Laser therapy
- Creation of drainage pathways
If the eyes are painful, they can also be removed, via a procedure called
Glaucome - The Updates
Simon M Petersen-Jones, DVetMed, PhD, DVOphthal, DipECVO, MRCVS
Department of Small Animal Clinical Sciences
College of Veterinary Medicine
D-208 Veterinary Medical Center
Michigan State University
East Lansing, MI 48824