title: Evaluation of retinal images for identifying individual dogs.
abstract: OBJECTIVE
  To F whether vessels in the ocular fundus changed over the lifetime of Beagles and whether any changes were substantial enough to likely preclude positive identification of individual dogs by use of their retinal vascular patterns.
  
  
  METHODS
  18 Beagles.
  
  
  METHODS
  Fundic photographs of both eyes of 18 Beagles taken at 1 or 3, 5, and 7 or 9 years of age were digitalized. Photographs were analyzed by use of 2 software programs. One was used to determine vessel numbers and widths and the other to determine the locations of the 3 largest vessels. Measurements were compared over time periods in the life of each dog. Only observations made at baseline (1 or 3 years of age) and again at 5 and 9 years of age were included in the statistical analysis, as these points were common to all dogs.
  
  
  RESULTS
  No significant changes in numbers or locations of the blood vessels were detected over time. Widths of the vessels decreased significantly as the dogs aged.
  
  
  CONCLUSIONS
  The ocular fundus of Beagles changed over each dog's lifetime in that the retinal blood vessels became smaller but did not change in number or location. Results suggest that digitalized retinal images can likely be used to identify dogs over their lifetimes.
authors.affiliation: College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO 80528, USA.
authors.forename: Juliet R
authors.initials: JR
authors.lastname: Gionfriddo
authors.forename: Arthur Claire
authors.initials: AC
authors.lastname: Lee
authors.forename: Terry A
authors.initials: TA
authors.lastname: Precht
authors.forename: Cynthia C
authors.initials: CC
authors.lastname: Powell
authors.forename: Kimberly K
authors.initials: KK
authors.lastname: Marren
authors.forename: Steven V
authors.initials: SV
authors.lastname: Radecki
mesh_terms: D000367:Age Factors; D000375:Aging / Q000502:physiology*; D000823:Animal Identification Systems / Q000379:methods / Q000592:standards / Q000662:veterinary*; D000818:Animals; D004285:Dogs / Q000033:anatomy & histology* / Q000502:physiology; D005260:Female; D005654:Fundus Oculi; D008297:Male; D010781:Photography / Q000662:veterinary; D012160:Retina / Q000033:anatomy & histology*