PERSISTENT PUPILLARY MEMBRANE

Persistent Pupillary Membrane is NOT life threatening, but should be considered when planning any breeding programme.

During foetal development, a fibrovascular tissue, the Pupillary Membrane, forms a layer across the front of the eye to form a blood supply to nourish the developing lens.  In the normal course of events, this temporary vascular mesoderm regresses and deteriorates and is generally completely gone by the time the puppy is 14 days old.

When the Pupillary Membrane does not deteriorate completely by age 14 days, it is labelled Persistent Pupillary Membrane (PPM).  It may persist for several months before disappearing, or the remaining strands may attach to the cornea and lens creating cataracts.

PPMs come in all shapes, sizes, and severities, may be very extensive and visible to the naked eye, or may be very small and require considerable magnification to be seen.  As a general rule, the condition does not significantly reduce vision but in extreme cases may cause marked reduction in vision or even blindness.  It has been estimated that the majority of Basenjis do have PPM to some degree.

PPM is believed to be an inherited failure of the pupillary membrane to deteriorate at the proper time.  The exact mode of inheritance of PPM has not been determined.  Siblings of the same litter may be mildly or severely affected, and mildly affected animals may produce severely afflicted offspring.  It is also not known what effect the pregnant bitch's diet may have on the development of PPM.    Examination for PPM should be done by a veterinarian ophthalmologist through the use of a 'slit lamp' exam when the puppy is 2-4 months of age.

Coloboma is a depression or perforation in the optic disk which is sometimes associated with severe PPM.  An examination for this condition should be made before administering drops to dilate the eye when checking for PPM.

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