What is glaucoma in Shih Tzu? Causes, Symptoms, Diagnosis, Treatment, Prognosis, and Prevention. Our puppies use their eyes for many things – exploring their surroundings, playing fetch, and spotting squirrels – so when issues like glaucoma in dogs arise, immediate veterinary attention is needed.
If you notice that your Shih Tzu’s eyes are cloudy and they seem to be in pain, it could be glaucoma, a frequently painful eye condition that requires immediate diagnosis and treatment. Here’s what to expect if your dog is diagnosed with glaucoma.
What is glaucoma in Shih Tzu?
Glaucoma in Shih Tzu: Cloudy Eyes
Glaucoma is an increase in intraocular pressure caused by the buildup of aqueous humor, fluid in the eye that nourishes and provides oxygen to the entire eye. The fluid exits the eye through the drainage angle located between the iris and the cornea.
A balance between the production and drainage of aqueous humor keeps intraocular pressure within normal limits. Pressure increases when this balance is disrupted, and aqueous humor doesn’t drain properly. The increased pressure damages the retina and the optic disc, leading to permanent blindness.
Glaucoma in Shih Tzu is classified as primary or secondary. Primary glaucoma is hereditary and involves a genetic malformation of the drainage angle, preventing proper drainage of aqueous humor. Primary glaucoma can further be classified as “open-angle” or “closed-angle.” Open-angle primary glaucoma develops gradually, while closed-angle primary glaucoma (goniodysgenesis) develops rapidly.
Secondary glaucoma is the most common form of glaucoma in Shih Tzu and is caused by an underlying eye condition. Glaucoma can affect one or both eyes. Typically, the unaffected eye will develop glaucoma within a year after the other eye develops glaucoma.
What Causes Glaucoma in Shih Tzu?
Glaucoma is caused by the blockage of drainage of aqueous humor from the eye. There are some breeds genetically predisposed to primary glaucoma, including Shih Tzu, Cocker Spaniel, Poodle, Beagle, Basset Hound, and various terrier breeds. Several eye conditions can cause secondary glaucoma, including eye inflammation, lens luxation, eye tumors, eye trauma, and cataracts.
What Are the Symptoms of Glaucoma in Shih Tzu?
The initial signs of glaucoma in dogs are challenging to detect. Glaucoma symptoms become more pronounced as the disease progresses, whether rapidly or gradually. Symptoms may include:
Vision loss
Eye scratching
Redness of the eyes
Droopy eyelids
Cloudy and hazy blue eyes
Bulging eye (buphthalmos)
Dilated, slow, and unresponsive pupils
Pain, demonstrated by squinting and excessive tearing
Secondary glaucoma causes additional symptoms like the iris adhering to the cornea and inflammatory debris in front of the eye. You may also observe more general symptoms like hiding, reduced appetite, decreased activity levels, and pressing the head to relieve pressure.
Diagnosis of Glaucoma in Shih Tzu
Schedule an appointment with your veterinarian as soon as your Shih Tzu shows signs of glaucoma. After discussing your dog’s medical history, inform your vet about your dog’s symptoms and when they started, as well as any history of eye injuries or other eye issues.
Your veterinarian will then perform an eye examination. They will measure intraocular pressure using a tonometer. Normal intraocular pressure in dogs is 15 to 25 mm Hg. In Shih Tzu with glaucoma, the pressure can reach 45 to 60 mm Hg. Your veterinarian will also examine your Shih Tzu’s eyes for other abnormalities.
Your vet may refer you to a veterinary ophthalmologist for advanced eye tests. One such test is gonioscopy, which assesses the drainage angle in dogs with goniodysgenesis. Another advanced eye test is electroretinography, which evaluates retinal function.
Both eyes will be examined, even if only one eye is affected.
Treatment for Glaucoma in Shih Tzu
Glaucoma is treated as a medical emergency due to the risk of permanent blindness that can occur within hours if intraocular pressure is not reduced. Treatment is expected to reduce intraocular pressure, alleviate pain, increase aqueous humor drainage, and decrease aqueous humor production, either through medications or surgery.
Some medications enhance aqueous humor drainage and decrease its production; others include pain relievers. Both are administered as tablets or eye drops and are given if there is no vision loss. If vision loss occurs, surgical therapies become the preferred treatment option.
Cyclocryotherapy is a non-invasive surgical procedure that freezes cells producing aqueous humor. Goniovalve surgical therapy creates an alternative path for aqueous humor to exit the eye. Enucleation, or complete eye removal, is for end-stage glaucoma in dogs when there is permanent blindness.
Your veterinarian will determine the best treatment option for your Shih Tzu based on the type of glaucoma your dog has and how advanced it is. Treatment is typically long-term and requires regular monitoring of both the affected and unaffected eye.
What Is the Prognosis for Glaucoma in Shih Tzu?
Glaucoma is not curable. Long-term medical therapy often fails, and Shih Tzus becomes blind, requiring surgery. Fortunately, dogs adapt well to vision loss and can still enjoy their lives.
How to Prevent Glaucoma in Shih Tzu
Primary glaucoma cannot be prevented because it is hereditary. However, if you have a breed predisposed to glaucoma, regular eye monitoring can detect glaucoma early so that treatment can begin as soon as possible.
Preventing eye injuries is the primary way to prevent secondary glaucoma in Shih Tzu.