What are persistent pupillary membranes (PPM)?
Persistent pupillary membranes are strands of tissue in the eye. They are remnants of blood vessels which supplied nutrients to the developing lens of the eye before birth. Normally these strands are gone by 4 or 5 weeks of age.
Depending upon the location and extent of these strands, they may interfere with vision. They may bridge from iris to iris across the pupil, iris to cornea (may cause corneal opacities), or iris to lens (may cause cataracts), or they may form sheets of tissue in the anterior chamber of the eye. In many dogs these tissue remnants cause no problems.
How are persistent pupillary membranes inherited?
Inheritance is not defined.
What breeds are affected by persistent pupillary membranes?
PPM are known or strongly suspected to be inherited in the basenji, Pembroke and Cardigan Welsh corgi, mastiff, and chow chow. This problem is particularly significant in the basenji where the strands often bridge to the cornea, causing opacities which may impair sight. In the basenji the condition has been seen with optic nerve coloboma - a cavity in the optic nerve which, if large, causes blindness.
PPM are also seen in many other breeds, including the Akita, Alaskan malamute, American and English cocker spaniel, Australian shepherd, basset Griffin vendeen (petite), beagle, bearded collie, Belgian sheepdog, Belgian tervuren, Bichon frise, Bouviers des Flandres, Chesapeake Bay retriever, collie (rough and smooth), Doberman pinscher, English springer spaniel, golden retriever, Gordon setter, Havenese, Irish setter, Labrador retriever, Lakeland terrier, Lowchen, miniature bull terrier, Norwegian elkhound, Nova Scotia duck tolling retriever, Old English sheepdog, papillon, poodle (all sizes), Portuguese water dog, samoyed, Scottish terrier, Shetland sheepdog, soft-coated wheaten terrier, Tibetan terrier, Welsh springer spaniel, West Highland white terrier, Yorkshire terrier.
For many breeds and many disorders, the studies to determine the mode of inheritance or the frequency in the breed have not been carried out, or are inconclusive. We have listed breeds for which there is a consensus among those investigating in this field and among veterinary practitioners, that the condition is significant in this breed.
What do persistent pupillary membranes mean to your dog & you?
Generally persistent pupillary membranes cause no problems. However if attached to the cornea or lens, the strands can cause opacities which may interfere with vision. The cataracts that can occur with PPM usually don't worsen.
How are persistent pupillary membranes diagnosed?
PPM are seen in young dogs. You or your veterinarian may notice small white spots in your dog's eyes, or you may suspect that your dog's vision is impaired if the condition is severe. With an ophthalmoscope, your veterinarian will be able to see the membranous strands, and whether they adhere to the lens or cornea.
How are persistent pupillary membranes treated?
There is no treatment for the membranes themselves and in most cases there are no associated problems. If there is significant edema or "bluing" of the cornea due to adhesions, hyperosmotic eyedrops may help. Surgery may be required if there are extensive cataracts.
This is a particularly common defect in basenjis. Affected dogs and their close relatives should not be used for breeding. Ideally, all basenjis, even those not obviously affected, should have careful ophthalmic examinations for PPM before their use in a breeding programme.
The defect is also significant in Welsh corgis (Pembroke and Cardigan), chow chows, and mastiffs. Affected dogs and their close relatives should not be used for breeding.
In other breeds, parents and siblings of affected dogs should be examined ophthalmoscopically. If close relatives are affected, breeding is discouraged. Where PPM appears to be an isolated incident, breeders may use their discretion.
FOR MORE INFORMATION ABOUT THIS DISORDER, PLEASE SEE YOUR VETERINARIAN.
Where to find more information?
Gelatt, K.N. 1991. Veterinary Ophthalmology. Lea and Febiger.
Copyright © 1998 Canine Inherited Disorders Database. All rights reserved.
Revised: April 11, 2000.