Retrospective and prospective study of progressive retinal atrophy in dogs presented to the veterinary hospital of the Federal University of Parana, Brazil

Abstract

Background: Progressive retinal atrophy (PRA) is one of the main causes of blindness in dogs. Despite its clinical importance, there is limited epidemiological information available, particularly in South America.
Aim: The main objective of this study was to perform a retrospective, and prospective analysis of PRA in dogs
admitted at the Veterinary Hospital of the Federal University of Paraná, Brazil.
Methods: Medical records of dogs admitted between 2014 and 2018 were selected through the archives of the
Comparative Ophthalmology Laboratory. A total of 130 dogs with medical records indicating clinical signs suggestive
of PRA, independent of the electroretinography confirmation, were selected. In order to investigate common
characteristics, each patient’s clinical history, ophthalmic examination, and visual status were reviewed (obstacle
course, pupillary light reflex, dazzle reflex, visual tracking to a cotton ball, and menace responses). Additionally, a
prospective study was performed, where flash electroretinography was performed on 30 animals with clinical signs suggestive of PRA, and 14 animals were selected for fundus photography. Data were assessed through descriptive and inferential statistics.
Results: A total of 2,055 dogs were evaluated between January 2014 and December 2018. Of those, 130 animals were presumptively diagnosed with PRA (6.33%), consisting of 18 different breeds and 27 dogs with a mixed pedigree.
Poodles were the most prevalent breed (n = 26; 20.00%), followed by Cocker Spaniels (n = 19; 14.62%). In the reported caseload, Pomeranians showed a considerably higher odds ratio for PRA development (15.36%). 
Conclusion: Pomeranians presented a high odds ratio, suggesting that further studies may be performed with breeds with a high potential for developing this disease.