To evaluate the frequency of ophthalmic disorders in 7 brachycephalic dog breeds referred to an academic veterinary ophthalmology service.
970 client-owned dogs of 7 brachycephalic breeds that were evaluated by the ophthalmology service in a veterinary teaching hospital from January 2008 through December 2017.
Medical records of 7 brachycephalic breeds (ie, Boston Terriers, English Bulldogs, French Bulldogs, Lhasa Apsos, Pekingese, Pugs, and Shih Tzus) were reviewed to collect data regarding patient signalment, ophthalmic diagnoses, affected eyes, and number and dates of visits.
Median age at the first examination was 7 years (range, 23 days to 22 years). The number of dogs seen for a first examination increased with age. Corneal ulcers, keratoconjunctivitis sicca, corneal pigmentation, immature cataracts, and uveitis were each diagnosed in ≥ 100 dogs and represented 40.4% (1,161/2,873) of all diagnoses. On the basis of anatomic location, 66.3% (1,905/2,873) of all disorders were located in either the cornea (1,014/2,873 [35.2%]) or adnexa (891/2,873 [31%]). There was a significant difference in breed proportion in the study population; of the 7 breeds studied, Shih Tzus (34.3% [333/970]), Pugs (20.8% [202/970]), and Boston Terriers (16.6% [161/970]) were the most prevalent breeds. The frequency of some diseases within the referral population was associated with breed.
CONCLUSIONS AND CLINICAL RELEVANCE
Findings suggested that the most prevalent disorders for the brachycephalic breeds in this ophthalmic referral population were corneal ulcers, keratoconjunctivitis sicca, corneal pigmentation, immature cataracts, and uveitis. Although all dogs shared brachycephalic features, the frequency of specific ophthalmic diseases varied between breeds.
To identify genetic associations with primary glaucoma (PG) in American Cocker Spaniels using a genome-wide association study (GWAS).
A nationwide ambidirectional case–control cohort study was performed in American Cocker Spaniels that had an ophthalmic examination performed by a veterinarian. Ninety-four dogs with PG (cases) and 111 dogs without glaucoma (controls) met phenotypic criteria and had a blood sample collected after receiving informed owner consent.
Genomic DNA was extracted from whole blood samples and genotyped (CanineHD BeadChip, Illumina Inc). A case–control GWAS using a linear mixed model was performed, and 3 significance thresholds were calculated (1) using a Bonferroni correction on all single nucleotide polymorphisms (SNPs) included in the GWAS, (2) using a Bonferroni correction on only the unlinked SNPs from a pruned data set, and (3) using 10,000 random phenotype permutations.
Following genotype data quality control, 89 cases and 93 controls were included in the GWAS. We identified an association on canine chromosome (CFA10); however, it did not reach statistical significance. Potential candidate genes within the surrounding linkage disequilibrium interval include coiled-coil domain containing 85A (CCDC85A) and extracellular growth factor containing fibulin extracellular matrix protein 1 (EFEMP1).
Primary glaucoma in the American Cocker Spaniel is a complex heterogeneous disease that may be influenced by a locus on CFA10. The candidate genes CCDC85A and EFEMP1 within the identified linkage disequilibrium interval have been shown to be involved in human open-angle glaucoma.