A technique for shotgun proteomic analysis of the precorneal tear film in dogs with naturally occurring primary glaucoma.

OBJECTIVE: To introduce a protocol for the characterization of protein patterns in tears of dogs with primary angle closure glaucoma (PACG) and primary open-angle glaucoma (POAG). ANIMALS: Nineteen dogs (25 eyes). METHODS: Tear samples were collected using a Schirmer tear strip, from dogs with PACG (PACG-affected eyes, n = 8; unaffected eyes predisposed to PACG, n = 7), POAG (n = 4), and healthy controls (n = 6). Protein precipitation and trypsin digestion were performed for analyses via liquid chromatography-tandem mass spectrometry. Proteins were identified using the SwissProt protein sequence database. Relative protein expression in 17 eyes (15 dogs) was evaluated using Proteome Discoverer 2.0. Pathway analyses were performed to investigate molecular mechanisms associated with primary glaucoma. RESULTS: Unique peptides were identified in 505 proteins, with Major allergen Can f 1 and albumin identified with high confidence. Proteins unique to tears from diseased eyes (PACG: n = 7; POAG: n = 14) were identified. Nucleoside diphosphate was unique to tears in PACG eyes naïve to therapy, while retinal binding protein and NSFL1 cofactor p47 were unique to medicated PACG eyes. Relative expression of 34 proteins differed between disease states. Pathway analyses identified that the 'inflammatory response' was among the top disease/disorders in dogs with primary glaucoma (PACG and POAG) but not in healthy controls. CONCLUSION: Tear samples suitable for mass spectrometry were readily obtained from pet dogs without needing specialized equipment. Further studies to validate the findings and explore potential candidate biomarkers for early disease detection and potential therapeutic targets are indicated.

Diffusion tensor imaging of the visual pathway in dogs with primary angle-closure glaucoma.

OBJECTIVE: To describe measurements of in vivo structures of the visual pathway beyond the retina and optic nerve head associated with canine primary angle-closure glaucoma (PACG). METHODS: A prospective pilot study was conducted using magnetic resonance diffusion tensor imaging (DTI) to obtain quantitative measures of the optic nerve, chiasm, tract, and lateral geniculate nucleus (LGN) in dogs with and without PACG. 3-Tesla DTI was performed on six affected dogs and five breed, age- and sex-matched controls. DTI indices of the optic nerve, optic chiasm, optic tracts, and LGN were compared between normal, unilateral PACG, and bilateral PACG groups. Intra-class correlation coefficient (ICC) was calculated to assess intra-observer reliability. RESULTS: Quantitative measurements of the optic nerve, optic tract, optic chiasm, and LGN were obtained in all dogs. There was a trend for reduced fractional anisotropy (FA) associated with disease for all structures assessed. Compared to the same structure in normal dogs, FA, and radial diffusivity (RD) of the optic nerve was consistently higher in the unaffected eye in dogs with unilateral PACG. Intra-observer reliability was excellent for measurements of the optic nerve (ICC: 0.92), good for measurements of the optic tract (ICC: 0.89) and acceptable for measures of the optic chiasm (ICC: 0.71) and lateral geniculate nuclei (ICC: 0.76). CONCLUSION: Diffusivity and anisotropy measures provide a quantifiable means to evaluate the visual pathway in dogs. DTI has potential to provide in vivo measures of axonal and myelin injury and transsynaptic degeneration in canine PACG.

Stereotactic Cortical Atlas of the Domestic Canine Brain.

The domestic canine (canis familiaris) is a growing novel model for human neuroscientific research. Unlike rodents and primates, they demonstrate unique convergent sociocognitive skills with humans, are highly trainable and able to undergo non-invasive experimental procedures without restraint, including fMRI. In addition, the gyrencephalic structure of the canine brain is more similar to that of human than rodent models. The increasing use of dogs for non-invasive neuroscience studies has generating a need for a standard canine cortical atlas that provides common spatial referencing and cortical segmentation for advanced neuroimaging data processing and analysis. In this manuscript we create and make available a detailed MRI-based cortical atlas for the canine brain. This atlas includes a population template generated from 30 neurologically and clinically normal non-brachycephalic dogs, tissue segmentation maps and a cortical atlas generated from Jerzy Kreiner's myeloarchitectonic-based histology atlas. The provided cortical parcellation includes 234 priors from frontal, sensorimotor, parietal, temporal, occipital, cingular and subcortical regions. The atlas was validated using an additional canine cohort with variable cranial conformations. This comprehensive cortical atlas provides a reference standard for canine brain research and will improve and standardize processing and data analysis and interpretation in functional and structural MRI research.

Optical coherence tomography of the retina, nerve fiber layer, and optic nerve head in dogs with glaucoma.

OBJECTIVE: To evaluate the retina and optic nerve head (ONH) in canine eyes predisposed to glaucoma using optical coherence tomography (OCT). ANIMALS: Twenty-five eyes (24 dogs). METHODS: Measures of peripapillary retinal, retinal nerve fiber layer (RNFL), and ganglion cell complex (GCC) thickness and ONH parameters were obtained in vivo by OCT of the unaffected eye in dogs diagnosed with unilateral primary glaucoma (predisposed; n = 12) and compared with measures of healthy control eyes (normal; n = 13). Repeatability and intrarater reliability were explored using intraclass correlation coefficients (ICC). RESULTS: Compared to normal eyes, predisposed eyes had a thinner retina in the temporal (P = 0.005), inferior quadrants (P = 0.003), and decreased inner retinal thickness (superior: P = 0.003, temporal: P = 0.001, inferior: P < 0.001, nasal: P = 0.001). Predisposed eyes had a thinner RNFL compared to normal eyes (P = 0.005), and when analyzed in quadrants, it was thinner in the superior (P < 0.001), temporal (P = 0.034), and nasal quadrants (P = 0.001). Repeatability (ICC 0.763-0.835) and intrarater reliability (ICC 0.824-0.942) were good to excellent for measures of retinal thickness and adequate for RNFL measurements (ICC 0.701-0.798). Reliable measurements of optic disk area were obtained and were similar between groups (P = 0.597). Measurements of parameters relying on automated software detection (GCC, optic cup, optic rim) had inadequate repeatability and reliability. CONCLUSION: Statistically significant differences in retinal and RNFL thicknesses were identified in normal and predisposed eyes. Reliable and consistent measurements of variables with manual adjustment of software detected parameters were obtained. Validation of OCT as a diagnostic tool for clinical assessment in canine glaucoma is warranted.

Development of a vision impairment score for the assessment of functional vision in dogs: Initial evidence of validity, reliability, and responsiveness.

AIM: To describe the development and initial validation of a questionnaire measuring functional vision in dogs. METHODS: A 17-item survey was designed to quantify functional vision in dogs. The Vision Impairment Score (VIS) was determined by summing responses to each question. Questions were assigned to one of five subcategories: overall vision, daily activities, peripheral vision, near vision, and distance vision. Content validity was established during development phases, and construct validity via comparing results of known groups (blind vs sighted; normal vs impaired vision; surgery to improve vision vs nonrestorative surgery), and through factor analysis. Concurrent criterion validity was determined with use of a validated health-related quality-of-life (HRQL) assessment tool. Reliability and responsiveness assessments were investigated using intraclass correlation coefficient (ICC) and effect size (ES), respectively. RESULTS: Responses (221) from 201 dog owners were included. Compared to sighted dogs (n = 153), blind dogs (n = 48) had a higher VIS and greater impairment in all subcategories. Among sighted dogs, a higher VIS was obtained in dogs with low vision compared to those with normal vision (P < 0.001). A higher VIS was associated with poorer HRQL (P < 0.001). Perfect reliability was obtained for 6/17 questions, and excellent reliability for 11/17 questions (intraclass correlation 1.0 and >0.9, respectively), and the VIS was highly responsive to therapeutic intervention (effect size 1.46). CONCLUSION: Results suggest the VIS may be clinically useful in assessing and obtaining a quantifiable measure of functional vision in dogs. Ongoing validation of the tool for clinical use is needed.

Comparison of diode laser trans-scleral cyclophotocoagulation versus implantation of a 350-mm2 Baerveldt glaucoma drainage device for the treatment of glaucoma in dogs (a retrospective study: 2010-2016).

OBJECTIVE: To compare outcomes following trans-scleral cyclophotocoagulation (TSCP) and 350-mm2 Baerveldt implantation in the treatment of canine refractory glaucoma. DESIGN: Retrospective case study. CASE SELECTION: Client owned dogs undergoing surgical treatment of glaucoma within a veterinary referral hospital. PROCEDURES: Eighty-six glaucoma surgeries were performed on 83 eyes (69 dogs) diagnosed with primary or secondary glaucoma. Medical records were retrieved, and baseline data, surgery, medications, intraocular pressures (IOPs), vision, and complications were extracted. RESULTS: Fifty-four eyes (44 dogs) were treated with TSCP and placement of an anterior chamber suture shunt; 28 eyes (24 dogs) were implanted with a Baerveldt glaucoma drainage device (GDD); and four eyes (4 dogs) underwent GDD implantation after failure of TSCP to manage IOP. Following TSCP, IOP control (<20 mmHg) and vision retention occurred in 81.5% and 42.6%, respectively, for 16.1 ± 1.36 months. Following GDD implantation, 71.4% maintained IOP <20 mmHg and 69.6% maintained vision for 11.0 ± 0.94 months. IOP control without loss of vision was more likely following Baerveldt implantation (17/28; 60.7%) than TSCP (19/54; 35.2%) (P = 0.027). One eye had functional vision restored following GDD placement. IOP control without adjunctive medications was more likely following Baerveldt implantation (P = 0.02). CONCLUSIONS: In this study, eyes treated with Baerveldt GDD implantation were more likely to maintain IOP control and retain vision compared to eyes treated with TSCP and placement of an anterior chamber suture shunt. Lack of formal randomization, inconsistencies in surgical techniques and TSCP protocols, and potential unmeasured confounders must be considered when extrapolating from this retrospective study.

Intraocular sarcoma associated with lens capsule rupture and persistent hyperplastic primary vitreous in a dog.

This case report describes the clinical findings and ocular pathology in an adult Golden Retriever diagnosed with an intraocular sarcoma. Nineteen s prior to diagnosis with a lens capsule rupture and intraocular sarcoma, the dog was diagnosed with persistent hyperplastic primary vitreous and uveitis based on clinical signs and the ultrasonographic appearance of the eye. Two years after enucleation, there was no evidence of metastatic spread of the sarcoma. The immunohistochemical characteristics of the tumor as well as the limitations and supportive evidence used in attempting to identify the histogenesis of the tumor are outlined.

Feline corneal sequestra: outcome of corneoconjunctival transposition in 97 cats (109 eyes).

Case series summary A retrospective study was undertaken to review outcomes of keratectomy and corneoconjunctival transposition in cats with superficial and deep corneal sequestra. Information including pertinent history, signalment, ophthalmological findings and postoperative outcome was collected from medical records. Follow-up was obtained by clinical examination, contact with the referring veterinarians and review of medical records or telephone contact with owners. Ninety-seven cats (109 eyes) were included from 2005-2015. The most commonly affected breeds included Persian, Burmese and Himalayan. The mean age at the time of surgery was 6.8 years (median 6.5 years; range 8.0 months-18.0 years). A corneal sequestrum in the contralateral eye was diagnosed in 28 cats (28.9%). Recurrent corneal sequestration was diagnosed in eight cats (nine eyes), with recurrence occurring a mean of 703 days after surgery (range 29-1750 days). Age, sex, breed, depth of sequestration and concurrent ocular disease in the contralateral eye were compared between cats with and without recurrence, with no risk factors for recurrence identified. Relevance and novel information Excellent surgical outcomes have previously been described in a series of 17 cats with superficial and mid-stromal corneal sequestra. This paper adds further information to the literature by describing a larger series of cats, with corneal sequestra affecting the full range of corneal thickness, and good long-term postoperative outcomes.

Use of a 350-mm2 Baerveldt glaucoma drainage device to maintain vision and control intraocular pressure in dogs with glaucoma: a retrospective study (2013-2016).

OBJECTIVE: To evaluate the 350-mm2 Baerveldt glaucoma drainage device (GDD) in dogs with refractory glaucoma when modifications to address postoperative hypotony (extraluminal ligature; intraluminal stent) and the fibroproliferative response (intraoperative Mitomycin-C; postoperative oral colchicine and prednisolone) are implemented as reported in human ophthalmology. DESIGN: Retrospective case series. ANIMALS: Twenty-eight client-owned dogs (32 eyes) including seven dogs (nine eyes) with primary glaucoma and 21 dogs (23 eyes) with secondary glaucoma. METHODS: The medical records of all dogs undergoing placement of a 350-mm2 Baerveldt GDD at a veterinary ophthalmology referral service between 2013 and 2016 were reviewed. Signalment, diagnosis, duration and previous treatment of glaucoma, previous intraocular surgery, IOP, visual, and surgical outcomes were recorded. RESULTS: IOP was maintained <20mmHg in 24 of 32 (75.0%) eyes. Fourteen eyes (43.8%) required no adjunctive treatments to maintain this IOP control. Fewer doses of glaucoma medication were required following surgery. Vision was retained in 18 of 27 (66.7%) eyes with vision at the time of surgery. No eyes that were blind at the time of surgery (n = 5) had restoration of functional vision. Complications following surgery included hypotony (26/32; 81.3%), intraocular hypertension (24/32; 75.0%), and fibrin formation within the anterior chamber (20/32; 62.5%). The average follow-up after placement of the GDD was 361.1 days (median 395.6 days). CONCLUSION: Efforts to minimize postoperative hypotony and address the fibroproliferative response following placement of a 350-mm2 Baerveldt GDD showed an increased success rate to other reports of this device in dogs and offers an alternative surgical treatment for controlling intraocular pressure in dogs with glaucoma.