Five week old Sprague Dawley BR outbred albino rats and young mature purebred Beagle dogs, male and female

SIGNALMENT: (age, breed, sex, species, and scientific name) 
Five week old Sprague Dawley BR outbred albino rats and young mature purebred Beagle dogs, male and female.

HISTORY: 
Representative sections of retina in the rat and dog (with corresponding electron micrograph from one of the dogs) given Compound X once daily by gavage in the highest dose group for 9 months and 8 months respectively. One dog in the high dose group developed visual impairment. High dose dogs developed emesis, loose stools and increased their food consumption and water intake. In the high dose rats, 11 males and two females were found dead or sacrificed in moribund condition.   

OPHTHALMOSCOPIC RESULTS AND GROSS PATHOLOGY:  
In the rat, there was dose-related yellow discoloration of the retina. In the dog, ophthalmologic examination results included yellow or pale discoloration of the fundus, discoloration of the sclera, lack of clarity or cloudiness in the vitreous body, lack of clarity in the retina, and discoloration of the optic nerve. Cells/crystals were evident in the vitreous body; there was a decrease in the size of retinal vessels as well as abnormal responses to the pupillary light, menace, and visual placement tests. Other gross findings in the dog included discoloration of the mucous membranes, skin and/or toenails, dull, coarse faded haircoat, and a thin appearance.

LABORATORY RESULTS: (clinical pathology, microbiology, etc…)
Test article-related laboratory findings in the dog included increased serum TSH, increases in T3 and T4, minimal decreases in erythrocyte count, yellow serum, increases in alkaline phosphatase, minimal decreases in serum total protein, albumin and creatinine and dark yellow urine. Electrocardiographic findings in the dog included changes in T waves (increased amplitude, altered polarity, and spiked or dome-dart appearance), increased amplitude of the Q and R waves and increased amplitude of the S waves.

What's Your DiagnosisProvide your possible etiologies in the comment section

 

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40X H&E. Treated rat 

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40X H&E. Control canine nontapetal retina 

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40X H&E. Treated dog, nontapetal retina  

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Transmission electron micrograph, 3,600x, Control canine outer tapetal retina

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Transmission electron micrograph, 3,600x. Treated dog, nontapetal retina

 

1 Comment
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Retinal Degeneration/Atrophy

November 27, 2019 11:04 AM by Pritpal Singh Malhi, BVSc, MVSc, PhD, DAVCP

and Retinal detachment with RPE hypertrophy (in dog)

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