Bright Blindness in Sheep

Bright Blindness in Sheep

I have a wether sheep about 6 years old that apparently ate some bracken ferns ( Pteridium aquilinum [ Pteris aquilina ]) about 3 years ago and got "bright blindness" --- a condition where the pupils are permanently dilated (opened wide) and the sheep is blinded due to retinal degeneration and other eye problems from toxins in the brackens. One can recognize the condition by huge (open wide) pupils.

One on-line dictionary defines "bright-blindness" as a veterinary science term indicating blindness occuring in sheep after they have eaten bracken http://dictionary.reference.com/browse/bright-blindness .

A good summary of bright blindness can be found in the Merck Veterinary Manual. "Bright blindness in sheep is a progressive retinal atrophy that derives its name from the hyperreflectivity of the tapetum. Affected sheep are permanently blind and adopt a characteristic alert attitude. The pupils respond poorly to light, and ophthalmoscopic examination of sheep with advanced disease reveals narrowing of arteries and veins and a pale tapetum nigrum with fine cracks and spots of gray." http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/210400.htm .

I had to barricade HDPE-lined pond boundaries because I got tired of pulling a very heavy wet sheep out of the lined ponds. Now it runs into the barricades and turns away before falling into the ponds.

The sheep can eat on its own, and gets around by following its mom, or sticking close to some of the other sheep.
 
I learned the hard way that I need to make noise when approaching the afflicted sheep in the field. I almost got run over by a scared blind sheep a couple of times.
  
Adrian R. Lawler,  (C) 2012  --