Peaches is an eight-year-old Great Dane that recently grew fond of bumping into furniture. Her owner took notice that her left eye became red and cloudy. Her blinking patterns were also unusual. After a trip to the vet, Peaches got a glaucoma diagnosis. Less common among dogs, glaucoma is a severe veterinary condition. If not addressed early enough, glaucoma in dogs could lead to severe pain and blindness. Below is a detailed discussion of Glaucoma in dogs, including its symptoms and treatment.
What is Glaucoma in Dogs?
Just like human's, dogs may also suffer from an eye condition called glaucoma. What is this condition? Glaucoma is a condition that results from pressure build up in the eyes due to inadequate drainage of eye fluids. Intraocular Pressure or IOP is the pressure of the fluids inside the eye. Dogs, as well as humans, have an IOP that ranges between 10-20 mmHg in normal health. Any pressure above 30mmHg is cause to suspect glaucoma in dogs.
The eye is a spherical fluid globular organ that enables vision. A healthy canine eye produces clear fluids that maintain the shape of the organ as well as the nourishment of ocular tissues. This clear fluid is the same liquid that we know as tears. It also cleans and moisturizes the eye.
Tears exist outside the eye whereas aqueous humor naturally occurs inside the eye. Aqueous humor production happens in the eye. There is a need to maintain fluid pressure in the eye otherwise the eye will swell up. In a healthy eye, intraocular pressure is maintained by the drainage of aqueous humor through a porous sieve-like membrane back into the bloodstream. When there is a blockage in this porous membrane, intraocular pressure builds up in the eye thus risking pain and optical damage. Ignorance of intraocular pressure increase often leads to severe pain, swelling of the eye pain and eventual, blindness.
Types of Glaucoma in Dogs
There are two types of canine glaucoma.
- Primary Glaucoma: Physiological and physical predisposition causes primary glaucoma. The dog is exposed to the condition by genetic deficiencies. The inheritance of glaucoma-causing traits defines physical or genetic predisposition. These physical traits include small pores in the drainage membrane and narrow angles that lead to the blockage of pores. Even though a dog may be genetically predisposed to the condition, it is rare for the animal to suffer glaucoma in both eyes at the same time. It may take years or months before the other eye is affected.
- Secondary Glaucoma: External factors like trauma, eye injury and infection of the eye cause secondary glaucoma. Secondary glaucoma can arise in many ways. Firstly, Inflammation due to swelling after injury can cause an increase in intraocular pressure. Secondly, bleeding and scar formation may hinder fluid drainage through the blockage of passageways. Sometimes, trauma may damage lens attachment causing it to rest against the iris. This orientation blocks or impedes effective fluid drainage. Laxation, subluxation, and lens instability are terms used to describe lens displacement. Advanced cataracts, tumors, cancer of the eye, chronic retinal detachments are common infections that may trigger secondary glaucoma in dogs. All these conditions hinder proper drainage of the eyes.
Symptoms of Glaucoma in Dogs
Pain is the most prominent symptom of glaucoma in dogs. Animals do not express pain as humans do, and sometimes it is hard to tell when your dog is in pain. For glaucoma in canines, you should check out for signs like squinting of the eyelids and rubbing of the affected eye against furniture or your leg.
Headaches are common with glaucoma. You may notice your pet resting or pressing its head against something to relieve the pain. Loss or deviation from regular activity and loss of appetite is common with glaucoma in dogs.
High intraocular pressure stresses the optic nerve just like brain cells optic nerves are hard to repair. Stifled blood supply to the retina along with optic nerve damage eventually causes loss of vision. The animal tends to lose sight in one eye; and just like Peaches, in our story, you may notice your dog bumping into furniture, walls, and household items. Permanent blindness is a possible risk when you ignore optical nerve damage.
Bloodshot eyes and cloudy corneas are signs that indicate glaucoma in dogs. You cannot tell intraocular pressure from visual inspection of the animal (until it is too late), so instead, we study the eye. Sometimes, the affected eye appears to be protruding slightly, and sometimes the pupil seems larger.
IOP measurements are used to diagnose glaucoma in dogs. Your vet takes readings of your dog's intraocular pressure. Reading above 30mmHg indicate glaucoma.
Glaucoma Risk Factors
- Some breeds of dogs have a higher predisposition for glaucoma more than other breeds. These breeds include; Jack Russel Terriers, Beagles, Poodles, Samoyeds, Chow Chows, Cocker Spaniels, Siberian Huskies, Basset Hounds, Dalmatians, Schnauzers, Chihuahuas, Great Danes, and Alaskan Malamutes.
- Age is a risk factor when it comes to glaucoma in dogs. Glaucoma prevails in dogs over the age of two years.
- Once one eye is affected with glaucoma, it is just a matter of time before the other eye suffers the same condition.
Treatment of Glaucoma in Dogs
Glaucoma is an emergency medical condition, once identified, I recommend swift action through treatment. Treatment of glaucoma in dogs aims at pain management, fluid drainage, and reduction of the eye's ability to produce aqueous humor.
- Reducing Aqueous Humor Fluid: Draining the excess aqueous humor is a short-term solution to glaucoma if the eye will only produce more in the future. Solutions to reducing aqueous humor production include pills and eye drops. For a long-term solution, surgery is appropriate.
- Reduce stress: Stress affects the body's physiological functions. In the case of glaucoma in canines, pain in the form of headaches is a common cause of stress.
- Use of Dog Harnesses: Dog harnesses are perfect alternatives to collars. They do not exert unnecessary pressure on the jugular vein, and they suit walking dogs.
- Chemical Ablation: In cases where anesthesia is discouraged due to the dog's condition and age, chemical ablation is a good alternative. If vision is possible, laser surgeries are appropriate for IOP correction.
Is it possible to treat a blind eye? The treatment of an eye that has already suffered blindness is unnecessary as the process is expensive and stressful to the animal. Consult your veterinarian before making a decision. Sometimes it is best to remove the blind eye.
Prevention of Glaucoma in Dogs
Primary Glaucoma is not preventable. Altering the genetic makeup of an already existing dog is not possible. The best hope is treatment and early detection of the disease.
Secondary Glaucoma is preventable by keeping your dog safe from injuries and infections of the eyes.
In both cases of glaucoma, the blindness that results from glaucoma is preventable through early detection and treatment. Once the condition gets to blindness, options shrink to the removal of the affected eye. Glaucoma is a serious medical condition. The sooner it is detected the sooner blindness can be avoided.