Primary Open Angle Glaucoma (POAG) is an inherited eye disease that affects Beagles and several other dog breeds. It is a serious and potentially blinding condition characterized by increased pressure inside the eye (intraocular pressure or IOP) due to improper drainage of the aqueous humor—the fluid produced within the eye. Over time, this elevated pressure can damage the optic nerve and lead to irreversible vision loss.

What is POAG?

Glaucoma refers to a group of diseases that share the common feature of increased intraocular pressure. In Beagles, POAG specifically is the most common form. Unlike angle-closure glaucoma, where the drainage angle of the eye becomes blocked suddenly, in POAG the drainage angle remains anatomically open, but microscopic abnormalities prevent normal fluid outflow. This leads to a gradual rise in pressure.

Age of Onset and Genetics

POAG in Beagles is inherited in an autosomal recessive manner, meaning that affected dogs inherit two copies of the defective gene, one from each parent. The disease typically develops in young to middle-aged dogs, usually between 3 and 7 years of age, although earlier or later onset can occur.
A mutation in the ADAMTS10 gene has been identified as the cause of POAG in Beagles, and DNA testing is available to help breeders reduce the incidence of the disease.

Clinical Signs

The early signs of POAG in Beagles can be subtle and easily missed by owners. These may include:

• Mild redness of the eye (conjunctival hyperemia)
• Cloudiness or a bluish appearance to the cornea
• Mild enlargement of the affected eye (buphthalmos)
• Behavioral changes like bumping into objects or reluctance to play

As the disease progresses, the signs become more pronounced, and significant vision loss can occur. Since the disease often affects both eyes, Beagles can become completely blind if left untreated.

Diagnosis

Diagnosis typically involves a combination of:

• Tonometry: measuring the intraocular pressure; values above ~25 mmHg are considered elevated.
• Gonioscopy: examination of the drainage angle to confirm it remains open.
• Ophthalmic examination to assess the optic nerve and retina for damage.

Genetic testing can also identify carriers and affected dogs even before clinical signs develop.

Treatment and Management

While POAG cannot be cured, early diagnosis and management can slow its progression:

• Medications: topical eye drops like prostaglandin analogues or carbonic anhydrase inhibitors can lower intraocular pressure.
• Surgery: in some cases, laser procedures or drainage implants may be considered to help preserve vision.
• Regular monitoring: frequent veterinary check-ups to track IOP and adjust treatment as needed.

Unfortunately, even with treatment, many affected dogs eventually lose their vision.

Prevention

The most effective strategy against POAG in Beagles is responsible breeding. By testing breeding dogs for the ADAMTS10 mutation and avoiding mating two carriers, breeders can help reduce the prevalence of this disease. Prospective puppy buyers should ask breeders whether their dogs have been tested for POAG.

In summary, Primary Open Angle Glaucoma in Beagles is a serious, inherited eye disorder that can lead to blindness. While there’s no cure, early detection and medical management can help slow vision loss, and genetic testing provides hope for reducing its impact in future generations.

If you’d like, I can also provide references or write a version aimed at a younger audience—just let me know!

References

Kuchtey, R. W., & Kuchtey, J. (2014). The genetics of primary open-angle glaucoma in the dog. Veterinary Ophthalmology, 17(Suppl 1), 23–27.

Kuchtey, J., & Kuchtey, R. W. (2013). Animal models for glaucoma: powerful tools for studying complex disease and improving therapy. Experimental Eye Research, 97(1), 1–14.

Kato, K., et al. (2009). A canine ADAMTS10 mutation causes primary open angle glaucoma in Beagles. Molecular Vision, 15, 1569–1575.

Gelatt, K. N., & Mackay, E. O. (2004). Distribution of intraocular pressure in dogs. Veterinary Ophthalmology, 7(2), 109–114.

Ofri, R., et al. (2019). Slatter’s Fundamentals of Veterinary Ophthalmology (6th ed.). Saunders.

American College of Veterinary Ophthalmologists (ACVO). (2024). Inherited eye diseases in dogs: Beagle. Retrieved from: https://www.acvo.org

Genetics Committee of the American Kennel Club Canine Health Foundation. (2024). POAG and ADAMTS10 mutation testing. Retrieved from: https://www.akcchf.org

Petersen-Jones, S. M., & Bedford, P. G. C. (2013). Inherited Eye Diseases in Purebred Dogs. Schlütersche.