Primary Open Angle Glaucoma in Basset Dog Breeds Explained

Primary Open Angle Glaucoma (POAG) is a hereditary eye disease affecting several Basset dog breeds, including the Basset Hound, Basset Fauve de Bretagne, and Petit Basset Griffon Vendeen. This painful condition causes a gradual increase in intraocular pressure (IOP) due to impaired drainage of eye fluids, leading to optic nerve damage and ultimately blindness if untreated.

Unlike primary closed angle glaucoma, POAG progresses slowly with an open iridocorneal angle, meaning early stages may be painless and easily missed by owners. Typical onset for Basset breeds is between three and four years of age, with clinical signs such as red and inflamed eyes, widened pupils, cloudy corneas, and behavioural changes like eye rubbing or scratching.

Understanding Primary Open Angle Glaucoma

Glaucoma in dogs involves damage to the retinal ganglion cells due to elevated eye pressure. POAG is a genetic disorder distinct from secondary glaucoma, which can result from injury or other eye diseases. The genetic mutation linked to POAG in Bassets affects connective tissue in the eye, reducing aqueous humour drainage and causing pressure build-up.

This pressure increase leads to progressive optic nerve damage, resulting in blindness that cannot be reversed. Early detection by a vet specialising in ophthalmology is crucial for managing the condition and preserving vision as long as possible.

Breeds Affected by POAG

POAG has been confirmed as a genetic condition within the gene pools of several Basset breeds. Beyond the well-known Basset Hound, it affects the Basset Fauve de Bretagne and Petit Basset Griffon Vendeen. Non-pedigree dogs related to these breeds may also be at risk.

How POAG Heredity Works in Basset Dogs

POAG is inherited as an autosomal recessive trait, meaning a dog must inherit two copies of the mutated gene (one from each parent) to be affected. Dogs are categorised as:

• Clear: No copies of the mutation and not at risk.
• Carrier: One copy of the mutation, not affected themselves but can pass it on.
• Affected: Two copies, typically develop POAG.

This heritage pattern means carriers can unknowingly contribute to disease spread if not tested. Responsible breeding requires testing to avoid mating two carriers or an affected and a carrier.

Here are breeding outcomes based on parental gene status:

• Two clear dogs produce only clear puppies.
• Two affected dogs produce only affected puppies.
• Two carriers produce 25% affected puppies, 50% carriers, and 25% clear puppies.
• A clear and a carrier produce 50% carriers and 50% clear puppies.
• A clear and an affected dog produce 100% carrier puppies.
• A carrier and an affected dog produce 50% affected and 50% carriers.

Getting Your Basset Dog Tested for POAG

Testing is imperative to manage POAG risks responsibly. Your vet can collect a DNA sample via blood, cheek swab, or dewclaw clipping and send it to an approved laboratory for analysis. The test identifies whether your dog is clear, a carrier, or affected by the gene mutation.

In the UK, genetic testing for POAG is endorsed by The Kennel Club, assisting breeders in making informed decisions to reduce disease prevalence. Early testing also enables prompt veterinary eye examinations to catch clinical signs early and improve treatment outcomes.

Supporting Responsible Breeding and Ownership

POAG presents real challenges but can be mitigated effectively through awareness, testing, and responsible breeding practices. Breeders should ensure genetic screening is standard before mating pairs, avoiding carrier pairings that increase disease risk.

Owners of at-risk Basset breeds should monitor their dogs for early eye symptoms and seek veterinary advice promptly. Regular veterinary ophthalmologic exams can detect changes before irreversible damage occurs.

Through combined efforts from breeders and owners, the impact of Primary Open Angle Glaucoma on Basset dogs' welfare can be reduced, preserving their health and quality of life.

Conclusion

Primary Open Angle Glaucoma is a genetic, slowly progressing eye condition in Basset dogs that leads to increased eye pressure and vision loss. Early identification through genetic testing and veterinary eye exams is key to managing the condition and enabling responsible breeding. By understanding POAG's inheritance and supporting testing, breeders and owners can protect future generations of these beloved breeds.