Persistent pupillary membranes (PPM)

What is ... ?: 

 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 is ... inherited?: 

Inheritance is not defined.

What does ... 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 is ... 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 is ... 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.

Breeding advice: 

 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.

Resources: 

 Gelatt, K.N. 1991. Veterinary Ophthalmology. Lea and Febiger.


What breeds are affected by ... ?
Tags: