title: Prevalence and progression of pectinate ligament dysplasia in the Welsh springer spaniel.
abstract: OBJECTIVE
  To determine the prevalence of pectinate ligament dysplasia in a large group of Welsh springer spaniels; to investigate associations between pectinate ligament dysplasia and age, sex and intraocular pressure and between intraocular pressure and age and sex; and to investigate progression of pectinate ligament dysplasia in individual dogs.
  
  
  METHODS
  In a prospective study, gonioscopy was performed in both eyes of 227 Welsh springer spaniels and intraocular pressure measured by rebound tonometry. Eyes were classified as "unaffected" if 0% of the iridocorneal angle was affected with pectinate ligament dysplasia (grade 0), "mildly affected" if <20% was affected (grade 1), "moderately affected" if 20 to 90% was affected (grade 2) and "severely affected" if >90% was affected (grade 3). In a retrospective study, progression of pectinate ligament dysplasia over time was investigated for 65 dogs.
  
  
  RESULTS
  One hundred and thirty-nine of 227 dogs (61·2%) were affected by pectinate ligament dysplasia (grades 1 to 3) and 82/227 (36·2%) were moderately or severely affected. There was a significant association between pectinate ligament dysplasia and age. There were no associations between pectinate ligament dysplasia and intraocular pressure or pectinate ligament dysplasia and sex. Thirty-five of 65 dogs (53·8%) demonstrated progression of pectinate ligament dysplasia.
  
  
  CONCLUSIONS
  Prevalence of pectinate ligament dysplasia was high despite widespread screening and selection against the condition. Our data indicate that gonioscopic features of pectinate ligament dysplasia can progress in the Welsh springer spaniel. Dogs deemed unaffected at an early age may subsequently be diagnosed with pectinate ligament dysplasia.
authors.affiliation: Centre for Preventive Medicine, Animal Health Trust, Lanwades Park, Newmarket, Suffolk CB8 7UU.
authors.forename: J A C
authors.initials: JA
authors.lastname: Oliver
authors.affiliation: Centre for Preventive Medicine, Animal Health Trust, Lanwades Park, Newmarket, Suffolk CB8 7UU.
authors.forename: A
authors.initials: A
authors.lastname: Ekiri
authors.affiliation: Centre for Preventive Medicine, Animal Health Trust, Lanwades Park, Newmarket, Suffolk CB8 7UU.
authors.forename: C S
authors.initials: CS
authors.lastname: Mellersh
mesh_terms: D000818:Animals; D003430:Cross-Sectional Studies; D018450:Disease Progression; D004283:Dog Diseases / Q000453:epidemiology* / Q000473:pathology; D004285:Dogs; D005260:Female; D005901:Glaucoma / Q000453:epidemiology / Q000473:pathology / Q000662:veterinary*; D006068:Gonioscopy / Q000662:veterinary; D008297:Male; D010375:Pedigree; D015995:Prevalence; D011446:Prospective Studies; D006113:United Kingdom / Q000453:epidemiology