James Andrew Clive Oliver

Retinopathy with vitamin E deficiency is a familial disease in the English Cocker Spaniel dog breed. Ophthalmic abnormalities observed in retinopathy with vitamin E deficiency-affected English Cocker Spaniel include lipofuscin granule deposition within the tapetal fundus and subsequent retinal degeneration resulting in visual deficits. Affected dogs may also exhibit neurological signs that include ataxia and hindlimb proprioceptive deficits. In all cases, circulating plasma concentrations of α-tocopherol are low. This study sought to investigate the genetic basis of retinopathy with vitamin E deficiency in the English Cocker Spaniel breed. We undertook a genome-wide association study comprising 30 English Cocker Spaniels with normal fundic examinations aged 6 years or older (controls) and 20 diagnosed with retinopathy with vitamin E deficiency (cases) and identified a statistically associated signal on chromosome 29 (Praw = 1.909 × 10−17). Whole genome sequencing of 2 cases identified a 102 bp deletion in exon 1 of the alpha-tocopherol transfer protein gene (TTPA), truncating the protein by 34 amino acids. The c.23_124del variant segregated with retinopathy with vitamin E deficiency in a total of 30 cases and 43 controls. Variants in TTPA are causal for ataxia with vitamin E deficiency in humans which is a phenotypically similar disease to retinopathy with vitamin E deficiency. The identification of the canine variant is extremely significant as the availability of a DNA test will allow for identification of presymptomatic dogs and early therapeutic intervention which may prevent development of retinopathy and improve neurological signs. Breeders can also use the DNA test to efficiently eradicate the disease from this breed.

Objective: To assess in vitro antibacterial efficacy of three cross‐linking (XL) protocols on bacteria associated with canine ulcerative keratitis.Methods: Three XL protocols: UVA 3 mW/cm² for 60 min, UVA 3 mW/cm² for 30 min, and UVA 30 mW/cm² for 3 min with and without application of riboflavin and a riboflavin‐only protocol were performed in vitro on the four most common bacterial genera isolated from cases of canine ulcerative keratitis treated at Dick White Referrals, UK. Zones of bacterial growth inhibition (GIZ) associated with treatment were measured and compared.Results: The four most common isolates were Pseudomonas aeruginosa (PA) (48/140, 34.3%), Streptococcus spp. (32/140, 22.9%), Staphylococcus spp. (24/140, 17.1%) and Escherichia coli (EC) (11/140, 7.9%). PA, EC, Streptococcus canis (SC), and Staphylococcus pseudintermedius (SP), isolated from canine corneas, were selected for testing. EC and SC demonstrated growth inhibition following all UVA/riboflavin protocols. PA and SP only displayed growth inhibition following the 60 min UVA/riboflavin protocol. GIZ areas for 60 min UVA/riboflavin protocols were significantly greater than 30 and 3 min UVA/riboflavin protocols (p < .01) and there was no significant difference between 30 and 3 min UVA/riboflavin protocols. In respect to GIZ areas, EC was significantly more susceptible to XL than SP (p = <.01).Conclusions: All UVA/riboflavin XL protocols caused growth inhibition of EC and SC in vitro. PA and SP did not show clear growth inhibition in vitro following exposure to XL protocol settings of UVA 3 mW/cm² for 30 min and UVA 30 mW/cm² for 3 min.

Objective: The objective of the study was to compare corneal culture results using the ESwab™ and Amies charcoal swab.Animals studied: One hundred fourteen canine and fifteen feline eyes.Procedures: Retrospective analysis of Dick White Referrals bacterial and fungal corneal culture data was conducted. Results were included from canine and feline patients, which presented with suspected infectious keratitis that had samples taken using an Amies charcoal swab followed by an ESwab™ in the same eye. In respect to positive and negative cultures, a McNemar test was conducted comparing instances of disagreement between swab types, and the Kappa coefficient (κ) was calculated to assess the level of agreement between swab types.Results: The ESwab™ produced more positive corneal cultures (71/129 [55.0%]) than the Amies charcoal swab (41/129 [31.8%]). 2/129 eyes produced positive fungal cultures. Considering 37/129 eyes in which both swab types detected a positive corneal culture, the same bacterial species were cultured from each swab type in 34/37 (91.9%) eyes, and an additional bacterial species was cultured by the ESwab™ in 3/37 (8.1%) eyes. In 34/38 (89.5%), instances of disagreement between swab types, the ESwab™ showed a positive culture, and the Amies charcoal swab showed a negative culture from the same eye, and this difference was significant (p < 0.0001). There was a moderate level of agreement between results from both swab types (κ = 0.432).Conclusions: ESwab™ sampling alone may be superior to Amies charcoal swabs for detecting presence of bacteria in suspected infectious keratitis in cats and dogs.

Seven Northern Inuit Dogs (NID) were diagnosed by pedigree analysis with an autosomal recessive inherited oculoskeletal dysplasia (OSD). Short-limbed dwarfism, angular limb deformities and a variable combination of macroglobus, cataracts, lens coloboma, microphakia and vitreopathy were present in all seven dogs, while retinal detachment was diagnosed in five dogs. Autosomal recessive OSD caused by COL9A3 and COL9A2 mutations have previously been identified in the Labrador Retriever (dwarfism with retinal dysplasia 1—drd1) and Samoyed dog (dwarfism with retinal dysplasia 2—drd2) respectively; both of those mutations were excluded in all affected NID. Nine candidate genes were screened in whole genome sequence data; only one variant was identified that was homozygous in two affected NID but absent in controls. This variant was a nonsense single nucleotide polymorphism in COL9A3 predicted to result in a premature termination codon and a truncated protein product. This variant was genotyped in a total of 1,232 dogs. All seven affected NID were homozygous for the variant allele (T/T), while 31/116 OSD-unaffected NID were heterozygous for the variant (C/T) and 85/116 were homozygous for the wildtype allele (C/C); indicating a significant association with OSD (p = 1.41x10^-11). A subset of 56 NID unrelated at the parent level were analysed to determine an allele frequency of 0.08, estimating carrier and affected rates to be 15% and 0.6% respectively in NID. All 1,109 non-NID were C/C, suggesting the variant is rare or absent in other breeds. Expression of retinal mRNA was similar between an OSD-affected NID and OSD-unaffected non-NID. In conclusion, a nonsense variant in COL9A3 is strongly associated with OSD in NID, and appears to be widespread in this breed.

Purpose: Canine primary closed‐angle glaucoma (PCAG) is a complex disease caused by multiple genetic factors. A c.590G>A variant inOLFML3was recently reported to be a candidate for pectinate ligament abnormality (PLA) and PCAG in the Border Collie. We investigated the association of this variant with PLA and PCAG in Border Collies from the United Kingdom.Methods: TheOLFML3variant was genotyped in 106 Border Collies comprising 90 with normal eyes (controls) and 16 with PLA (n = 11) and/or PCAG (n = 5) (cases). Genotyping was performed in an additional 103 Border Collies to estimate variant frequency within the population. To investigate the association of the variant with disease in other breeds, genotyping was performed in 337 non‐Border Collies with PLA and/or PCAG.Results: Of the 90 controls, 71 were homozygous for the wild‐type allele, two were homozygous for the variant, and 17 were heterozygous. Of the 16 cases, three were homozygous for the wild‐type allele, 11 were homozygous for the variant, and two were heterozygous. The association of the variant allele with disease was significant (P = 1.1 x 10⁻⁹). We estimated the frequency of this variant to be 4.4% within the United Kingdom Border Collie population, and it was not identified in clinically affected dogs of any other breed.Conclusions: This study confirms the association of theOLFML3variant with PLA and PCAG in Border Collies from the United Kingdom. DNA testing for the variant and selective breeding can reasonably be expected to result in a reduction of PLA and PCAG prevalence in the breed.

This study describes clinical and histopathological features, treatment, and outcome of cats diagnosed with ocular mycobacteriosis. Cases diagnosed from 2012 to 2017 were reviewed for (a) histopathological evidence of ocular (pyo)granulomatous inflammation containing acid-fast bacilli with mycobacterial morphology, (b) positive mycobacterial culture and/or mycobacterial DNA identified by polymerase chain reaction of ocular tissue, or (c) presumed mycobacteriosis based on ophthalmic examination and positive interferon-gamma release assay. Twenty-five cats (31 eyes) were included; 14 cats (17/31 eyes, 55%) were blind at presentation (unilateral: n = 12 cats; bilateral: n = 2 cats); one unilaterally affected cat later became bilaterally blind. Another 5 cats (7/31 eyes, 23%) became blind after initially being bilaterally visual (unilateral: n = 3 cats; bilateral: n = 2 cats). The commonest ocular finding was uveitis (87%). The main histopathological features were granulomatous to pyogranulomatous chorioretinitis with retinal detachment, anterior uveitis, optic neuritis, episcleritis, scleritis, and/or retrobulbar cellulitis. Nineteen cats (76%) had systemic signs, with disseminated disease being diagnosed in 9, defined by interstitial pulmonary disease, generalized lymphadenopathy, and/or nonocular infection. Nine cats were diagnosed with Mycobacterium bovis, 2 with Mycobacterium microti, 1 with Mycobacterium tuberculosis complex, and 1 with Mycobacterium avium-intracellulare complex. The infecting species was unknown in the remaining cats. Combined surgery (enucleation: n = 5 cats; biopsy: n = 3 cats) and systemic treatment with 2 or 3 appropriate antibiotics for 2 to 7 months resulted in remission in 8 of the 10 cats treated; however, the cat treated with dual therapy relapsed after 8 months. A total of 16 cats (64%) were euthanized; 2 were lost to follow-up.

Canine progressive retinal atrophies (PRA) are genetically heterogeneous diseases characterized by retinal degeneration and subsequent blindness. PRAs are untreatable and affect multiple dog breeds, significantly impacting welfare. Three out of seven Giant Schnauzer (GS) littermates presented with PRA around four years of age. We sought to identify the causal variant to improve our understanding of the aetiology of this form of PRA and to enable development of a DNA test. Whole genome sequencing of two PRA-affected full-siblings and both unaffected parents was performed. Variants were filtered based on those segregating appropriately for an autosomal recessive disorder and predicted to be deleterious. Successive filtering against 568 canine genomes identified a single nucleotide variant in the gene encoding NECAP endocytosis associated 1 (NECAP1): c.544G>A (p.Gly182Arg). Five thousand one hundred and thirty canids of 175 breeds, 10 cross-breeds and 3 wolves were genotyped for c.544G>A. Only the three PRA-affected GS were homozygous (allele frequency in GS, excluding proband family = 0.015). In addition, we identified heterozygotes belonging to Spitz and Dachshund varieties, demonstrating c.544G>A segregates in other breeds of German origin. This study, in parallel with the known retinal expression and role of NECAP1 in clathrin mediated endocytosis (CME) in synapses, presents NECAP1 as a novel candidate gene for retinal degeneration in dogs and other species.

In humans, ADAMTS17 mutations are known to cause Weill-Marchesani-like syndrome, which is characterised by lenticular myopia, ectopia lentis, glaucoma, spherophakia, and short stature. Breed-specific homozygous mutations in ADAMTS17 are associated with primary open angle glaucoma (POAG) in several dog breeds, including the Petit Basset Griffon Vendeen (PBGV) and Shar Pei (SP). We hypothesised that these mutations are associated with short stature in these breeds. Two hundred thirty-three PBGV and 66 SP were genotyped for their breed-specific ADAMTS17 mutations. The height of each dog was measured at the withers. We used linear (per allele) regression to assess the association between ADAMTS17 mutations and height as a continuous variable, and linear regression and likelihood ratio tests to assess the shape of the association by comparing a general model with a linear (per allele) model. The adjusted mean heights of affected, carrier, and clear PBGV were 33.49 cm (n = 21, 95% CI 32.78–34.19 cm), 34.88 cm (n = 85, 95% CI 34.53–35.25 cm), and 34.92 cm (n = 121, 95% CI 34.62–35.21 cm), respectively. The mean heights of affected, carrier, and clear SP were 43.96 cm (n = 9, 95% CI 41.88–46.03 cm), 47.56 cm (n = 28, 95% CI 45.50–48.63 cm), and 48.95 cm (n = 23, 95% CI 47.80–50.11 cm), respectively. There was a significant difference between the height of affected and clear animals in the PBGV (P = 0.001) and the SP (P = < 0.0001). ADAMTS17 POAG mutations are significantly associated with height in these breeds.

Purpose: To investigate the genetic basis of primary closed angle glaucoma (PCAG) in European Basset Hounds using genome-wide association and RNA sequencing strategies. Methods: DNA samples from 119 European Basset Hounds were genotyped on the 170 K SNP CanineHD BeadChip array (Illumina) comprising 37 with normal iridocorneal angles (controls), 57 with pectinate ligament abnormality (PLA cases), and 25 with PCAG (PCAG cases). Genome-wide association studies (GWASs) of the PLA and PCAG cases were conducted. Whole transcriptome sequences of iridocorneal angle tissues from five Basset Hounds with PCAG were compared with those from four dogs with normal eyes to investigate differences in gene expression between the affected and unaffected eyes in GWAS-associated loci. A variant in NEB, previously reported to be associated with PCAG in American Basset Hounds, was genotyped in cohorts of European Basset Hounds and non-Basset Hounds. Results: The GWASs revealed 1.4 and 0.2 Mb regions, on chromosomes 24 and 37, respectively, that are statistically associated with PCAG. The former locus has previously been associated with glaucoma in humans. Whole transcriptome analysis revealed differential gene expression of eight genes within these two loci. The NEB variant was not associated with PLA or PCAG in this set of European Basset Hounds. Conclusions: We identified two novel loci for canine PCAG. Further investigation is required to elucidate candidate variants that underlie canine PCAG.

Objective: To describe the visual outcome following phacoemulsification in English Cocker Spaniels (ECS) affected by cataracts and suspected progressive retinal atrophy (PRA).Animals studied: Fifty‐four client‐owned dogs.Procedures: A multicenter, retrospective study was performed including ECS with suspected PRA which underwent phacoemulsification. PRA was suspected on ophthalmic examination before and after surgery, and/or after electroretinography (ERG) was performed. Visual outcome was assessed by menace response per eye at seven time periods post‐surgery (P1= 25‐90 days, P2 = 91‐180 days, P3 = 181‐364 days, P4 = 365‐549 days, P5 = 550‐729 days, P6 = 730‐1094 days, and P7 ≥ 1095 days). Descriptive statistics were performed. Generalized estimating equations were used to identify predictors associated with vision after surgery. Odds ratio and confidence intervals were reported. Significance was set at P < 0.05. Owners were invited to participate in a questionnaire.Results: Phacoemulsification was performed in 85 eyes. Median age at surgery was 9.09 years (min. 2.17 years, max. 13.49 years). At all re‐examinations, up to and including P5, significantly more eyes were visual than before surgery (P ≤ 0.003). Odds for vision were significantly increased for eyes that underwent surgery. Electroretinograms were performed in 75/85 eyes that underwent surgery, demonstrating low b‐wave amplitudes. There was no significant effect of the age, gender, vision before surgery, presence of dazzle reflex, cataract stage or abnormality on gonioscopy on visual outcome. The questionnaire response rate was 48.2%. Most participants (92.5%) felt that cataract surgery led to improvement of the dog's quality of life.Conclusions: English Cocker Spaniels with suspected PRA may benefit from phacoemulsification with vision up to 2 years following surgery.