Dear Bonnie:
 
>I saw a post the other day where the ferret mom or dad remarked that their
>fuzzie had an eye problem - the pupils did not respond to light.  Does
>anyone know what could be the cause of this?
>
>Our Ziggy is a 5 1/2 year old DEW...  The he started bumping into things...
>Our regular vet looked for cataracts and said she could see nothing wrong.
>When he had his annual apparently undiagnosable illness this year, we had
>him at another vet more knowledgeable with ferrets and were told that the
>pupils were not reactive to light and that Ziggy was completely blind
>(I'll argue with that - some days I'm sure he can see shadows).
 
Pupil contraction is part of a protective reflex that originates when light
hits the retina.  If the pupils do not constrict in response to light, then
there are three possibilities - something is blocking the from hitting the
retina, such as a cataract, which clouds the lens (which sits between the
pupil and retina).  The other possibility is that the retina is not
working.  The most common cause in ferrets is retinal atrophy, a
progressive loss of the rods and cones.  The last and least likely would
be previous administraitohn of drugs which either constrict or dilate the
pupils (and usually aren't used in ferrets.)
 
Or the patient is dead (just like in the movies.)
 
But I would ahve to agree with your vet - if the pupils don't constrict
when a bright light is shown directly into the eye in a dark room, that
ferret is blind.  But blind ferrets actually do very well - as you know
(and sometimes even convince their owners that they are partially sighted!)
 
With kindest regards,
Bruce Williams, DVM
[Posted in FML issue 3311]