Persistent Pupillary Membranes in Dogs: Causes and Care

Persistent Pupillary Membranes (PPM) are thin strands of tissue seen in the eyes of some dogs. These are leftover blood vessels that once nourished the puppy's lens during gestation. Typically, these strands fade and disappear by four to five weeks of age, but in certain dogs, they remain, which is why the condition is called persistent pupillary membranes.

PPM is a genetic condition passed from parent dogs to their offspring, although the precise hereditary mechanism is not fully understood. Many dogs with these tissue remnants show no symptoms, but the effect on vision can vary depending on where and how extensive the membranes are inside the eye.

Breeds Commonly Affected by Persistent Pupillary Membranes in the U.S.

Some dog breeds have a higher chance of developing PPM. These include:

• Basenji puppies
• Pembroke Welsh Corgi puppies
• Cardigan Welsh Corgi puppies
• Bullmastiff puppies
• Chow Chow puppies
• Yorkshire Terrier puppies

Among these, Basenjis frequently exhibit a form of PPM where the tissue forms a connection to the cornea, leading to cloudiness that can notably hinder vision. This breed is also sometimes affected by optic nerve coloboma, which in rare cases can cause blindness.

How Veterinarians Diagnose PPM

Veterinarians often identify Persistent Pupillary Membranes in puppies when they spot white spots or thread-like structures in the eye during early checkups. A thorough eye examination is performed using specialized tools like an ophthalmoscope or slit-lamp. The examist looks at the membranes' presence and placement—whether attached to the cornea, lens, or elsewhere—and evaluates any potential impact on the dog's sight and eye health.

Approaches to Managing and Treating PPM

There is no direct cure to remove PPM itself. However, veterinarians may prescribe eye drops to ease any discomfort or irritation. If complications like cataracts arise, surgery may be recommended to restore better vision. Thankfully, cataracts related to PPM tend not to worsen significantly since PPM is a non-progressive disorder.

Encouraging Responsible Breeding to Lower PPM Cases

Reducing the prevalence of PPM hinges largely on responsible breeding practices. Breeders should refrain from pairing dogs known to have PPM, regardless of breed, since the trait can be passed down.

For example, in breeds such as the Basenji, breeders should carefully screen litters by having puppies examined by a veterinary ophthalmologist at approximately nine weeks old. The Orthopedic Foundation for Animals (OFA) Eye Certification Registry can also be used to verify eye health, although it does not guarantee puppies will be without PPM.

Living Well with a Dog Diagnosed with PPM

Most dogs affected by Persistent Pupillary Membranes live normal, active lives. The condition often causes minimal to no impact on quality of life because it does not worsen over time. For many puppies, the membranous strands are reabsorbed naturally as they grow.

Serious vision impairment is rare, and dogs usually adapt well even with some visual challenges. Regular veterinary visits remain important to monitor eye health and maintain overall well-being.