PPMs as they are often called are common findings on CERF examinations. They may or may not
be a problem in a breed and/or individual dogs. PPMs are remnants of a fetal structure called the pupillary
membrane. This membrane covers the pupil before an animal is born. It is part of the blood supply to the
developing lens (the structure in the eye that focuses light on the retina). Normally the pupillary membrane
completely absorbs before birth in foals and calves but is partially present and continues to disappear in
neonatal dogs. Absorption may not be complete in puppies when the eyes first open and small strands or a
web-like structure may be seen across the pupil. These strands normally disappear by four to five weeks of
age. In some dogs these strands do not disappear and become PPMs.

PPMs may be found in several configurations in the anterior chamber. They may span across the
pupil (iris to iris), from the iris to the lens, from the iris to the cornea, or they may float free on one end, only
connected to the iris. In general, iris to iris PPMs cause no problems. They may be single strands or a forked structure. These PPMs may break and become less prominent as the puppy gets older, but they usually do not disappear completely.

 Iris to lens PPMs are more problematical. These PPMs cause opacities (cataracts) at the point where they are attached to the lens capsule. The cataracts do not usually progress and cause only minor visual deficits.

Iris to cornea PPMs causes opacities on the cornea due to their ability to damage the corneal endothelium (the inner lining of the cornea). These opacities may be small or may be severe due to the
development of corneal edema (fluid in the cornea). Severely affected puppies (with numerous strands) may be blind (they may improve as they get older). The strands may regress but do not disappear.

PPMs are found in many breeds of dog. In most of these breeds, iris to iris PPMs are classified by CERF as a “breeder option" problem. This means that most of the PPMs which have been reported in these breeds have been small and are probably sporadically occurring and not hereditary defects. Dogs with these small iris to iris PPMs who have been bred have not been reported to have puppies with vision problems. This does not mean that problems will never occur in these breeds. Owners with dogs diagnosed with PPMs should be aware of the situation and should probably either not breed affected dogs or should breed the affected dogs only to unaffected dogs.

In some breeds, PPMs are known to be hereditary and puppies who have any type of PPM will not receive a certification number. The Basenji is the most well known but CERF will also not certify Chow Chows, Mastiffs,  Pembroke Welsh Corgis, or Yorkshire Terriers with PPMs. Members of these breeds have been shown to  produce offspring with blindness directly associated with their PPMs. In these breeds, the mechanism of inheritance is not known but breeding any of these dogs with PPMs is highly discouraged.

Love your dog enough to enable future offspring the ability to see. CERF your dogs before breeding!!

How are persistent pupillary membranes inherited?
Inheritance is not defined. 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.

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 eye drops 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.
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Top 10 Dog Peeves About Humans

1. Blaming your farts on me... not funny... not funny at all!!!
2. Yelling at me for barking... I'M A FRIGGIN' DOG, YOU IDIOT!
3. Taking me for a walk, then not letting me check stuff out.
Exactly whose walk is this anyway?
4. Any trick that involves balancing food on my nose... stop it!
5. Any haircut that involves bows or ribbons... now you know why we chew your stuff up when you're not home.
6. The slight of hand, fake fetch throw. You fooled a dog! WhooooHoooooooo what a proud moment for the top of the food chain.
7. Taking me to the vet for "the big snip", then acting surprised when I freak out every time we go back!
8. Getting upset when I sniff the crotches of your guests. Sorry, but I haven't quite mastered that handshake thing yet!
9. Dog sweaters. Hello ???... Haven't you noticed the fur?
10. How you act disgusted when I lick myself. Look, we both know the truth, you're just jealous.
Now lay off me on some of these things, We both know who's boss here!!!

You Don't See Me Picking Up Your Poop Do You?

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