Just Ask the Expert: What's causing this dog's sudden blindness and polyphagia?


Just Ask the Expert: What's causing this dog's sudden blindness and polyphagia?

Mar 01, 2011

Dr. Byers welcomes critical care questions from veterinarians and veterinary technicians.
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Alice, my patient and my own dog, has acutely and progressively gone blind over the past two weeks. She is a 13-year-old spayed female Staffordshire terrier. Her vaccination status is current, she is receiving internal and external parasite preventives, and she has had no exposure to toxins. She has not had any polyuria or polydipsia but has become noticeably polyphagic. She seems disoriented, and some movements are what I would call jerky or sudden. Her gait and the rest of her initial neurologic examination findings were normal. Her complete blood count, serum chemistry profile, and urinalysis results were normal, as were her pupil sizes and pupillary light reflexes. Could she have a tumor on her optic chiasm or another neurologic condition?

Dr. Christopher G. Byers
A. Alice's clinical signs are interesting and, unfortunately, not very clear-cut. If the primary issue is ultimately a visual deficit with behavioral changes, perhaps the jerky movements are secondary to this deficit. However, these movement abnormalities may certainly be secondary to something more sinister such as a cerebellar lesion or a prosencephalic lesion, and, thus, multifocal disease must be considered.

I first recommend a blood pressure measurement and then a complete ophthalmic examination to rule out sudden acquired retinal degeneration syndrome (SARDS), progressive retinal atrophy (PRA), and a hypertensive retinopathy. This examination will also allow evaluation for possible optic neuritis. If no abnormalities are documented on ophthalmic examination, evaluation by a neurologist to follow with advanced imaging (particularly magnetic resonance imaging) and cerebrospinal fluid evaluation are likely needed.