Pathology in Practice.

In collaboration with the American College of Veterinary Pathologists.

Effects of chronic low-dose radiation on cataract prevalence and characterization in wild boar (Sus scrofa) from Fukushima, Japan.

This study evaluated cataracts in wild boar exposed to chronic low-dose radiation. We examined wild boar from within and outside the Fukushima Exclusion Zone for nuclear, cortical, and posterior subcapsular (PSC) cataracts in vivo and photographically. Plausible upper-bound, lifetime radiation dose for each boar was estimated from radioactivity levels in each animal's home range combined with tissue concentrations of 134+137Cesium. Fifteen exposed and twenty control boar were evaluated. There were no significant differences in overall prevalence or score for cortical or PSC cataracts between exposed and control animals. Nuclear (centrally located) cataracts were significantly more prevalent in exposed boar (p < 0.05) and had statistically higher median scores. Plausible upper-bound, lifetime radiation dose ranged from 1 to 1,600 mGy in exposed animals, with no correlation between dose and cortical or PSC score. While radiation dose and nuclear score were positively associated, the impact of age could not be completely separated from the relationship. Additionally, the clinical significance of even the highest scoring nuclear cataract was negligible. Based on the population sampled, wild boar in the Fukushima Exclusion Zone do not have a significantly higher prevalence or risk of cortical or PSC cataracts compared to control animals.

Iridocorneal angle assessment of companion rabbits using gonioscopy, spectral-domain optical coherence tomography (Optovue iVue® ), high-resolution ultrasound, and Pentacam® HR imaging.

OBJECTIVE: Iridocorneal angle (ICA) narrowing is a known risk factor for primary glaucoma in multiple species, but has not been described in companion rabbits. This study aimed to develop an ICA grading scheme for companion rabbits to enable early glaucoma predisposition diagnosis. ANIMALS STUDIED: Twenty healthy rabbits of varying breeds and ages. PROCEDURES: Rabbits received complete ophthalmic examinations, including gonioscopy, and imaging of the ICA using spectral-domain optical coherence tomography (SD-OCT), Scheimpflug imaging (Pentacam® HR), and high-resolution ultrasound (HRUS). Angle opening distance (AOD) and angle recess area (ARA) of the ICA were measured and assessed for agreement using a Bland-Altman analysis. A five-stage gonioscopy grading scheme was created, and Spearman-rank test assessed for correlation between gonioscopy grades and ICA measurements. Differences among age and sex were analyzed with a nonparametric ANOVA and Wilcoxon rank-sum test, respectively. RESULTS: Analysis revealed AOD medians of 0.28mm for SD-OCT [95% CI: 0.24-0.31], 0.20mm for Pentacam® HR [95% CI: 0.18-0.21], and 0.25mm for HRUS [95% CI: 0.22-0.28]. The median ARA was 0.14mm2 for SD-OCT [95% CI: 0.117-0.163], 0.09mm2 for Pentacam® HR [95% CI: 0.082-0.100], and 0.06mm2 for HRUS [95% CI: 0.046-0.054]. The association between gonioscopy grade and SD-OCT ARA was significant (P < 0.05), and there was a significant difference (P < 0.001) between imaging modalities for both ARA and AOD. CONCLUSIONS: Gonioscopy grade correlated well with SD-OCT ARA. Therefore, SD-OCT is recommended as a noncontact method for evaluating companion rabbit ICA. Each imaging device should not be used interchangeably for ICA evaluation.

Surgically induced astigmatism in canines following sutured dorsonasal vs dorsotemporal clear corneal incisions.

OBJECTIVES: To investigate use of the Pentacam® HR for evaluation of surgically induced corneal astigmatism (SIA) in canines undergoing bilateral phacoemulsification and determine differences between dorsonasal and dorsotemporal clear corneal incisions. ANIMALS: Client-owned canines undergoing bilateral phacoemulsification. PROCEDURES: Patients received anterior segment imaging pre-operatively, immediately post-operatively, and 2-4 months post-operatively (follow-up). Total corneal refractive power was used to determine SIA. Surgically induced astigmatism was compared between right and left eyes, representing dorsotemporal and dorsonasal incisions, respectively. Repeated measures analyses were used between time points and paired t test compared SIA between eyes. RESULTS: Complete imaging series were obtained for seven patients. Follow-up imaging occurred at a median of 112 days (range 60-132 days) post-operatively. For repeated measures analyses, significant differences were found between pre- and immediate post-operative values (P < 0.01), and between immediate post-operative and follow-up values (P < 0.01). There was no significant difference between pre-operative and follow-up values. Surgically induced astigmatism was significantly different between right and left eyes, with values of 2.01 ± 1.24 D and 3.05 ± 1.58 D at 3 mm radius (P < 0.05), and 2.04 ± 1.18 D and 3.06 ± 1.27 D at 4 mm radius (P < 0.05) for dorsotemporal and dorsonasal incisions, respectively. CONCLUSIONS: Preliminary investigation revealed improvement of corneal SIA 2-4 months post-operatively, but development of significantly more SIA in dorsonasal vs dorsotemporal incisions. This prompts consideration of patient or microscope rotation to create a more dorsotemporal incision when possible.

Anterior segment parameters in normal dogs using the Pentacam® HR Scheimpflug system.

OBJECTIVE: To describe and compare normative anterior segment parameters between canine age groups using the Pentacam® HR Scheimpflug camera (Pentacam). ANIMALS STUDIED: Thirty-six sedated dogs (60 eyes) of varying ages and breeds were imaged with the Pentacam; only nondiseased anterior segments were included. PROCEDURES: Dogs were divided into three age groups: Group 1 (1-5 years), Group 2 (6-10 years), and Group 3 (11-15 years). Values assessed included central corneal thickness (CCT), anterior and posterior corneal elevation (ACE/PCE), anterior and posterior corneal curvature metrics, corneal volume (CV), anterior and posterior corneal astigmatism (AA/PA), anterior chamber depth (ACD), anterior chamber volume (ACV), and anterior chamber angle (ACA). Tukey-adjusted pairwise comparisons were performed. RESULTS: Overall CCT (mean ± SD) was 631.07 ± 59.91 µm. Central corneal thickness was 608.60 ± 48.63 µm for Group 1, 648.57 ± 51.06 µm for Group 2, and 635.37 ± 73.71 µm for Group 3. Anterior corneal elevation (ACE) measured 9.08 ± 0.58 mm, PCE measured 8.04 ± 0.50 mm, and CV was 58.13 ± 5.39 mm3 . Astigmatism values were 1.34 ± 0.94 D for AA and 0.46 ± 0.44 D for PA. Anterior chamber values were 3.76 ± 0.56 mm for ACD, 383.68 ± 66.24 mm3 for ACV, and 23.62 ± 29.33˚ for ACA. Significant differences were found between Groups 1 and 2 for CV (55.08 ± 4.08 mm3 and 60.32 ± 4.19 mm3 , respectively), (P = 0.02). CONCLUSIONS: Corneal volume significantly increased between Group 1 and Group 2. Central corneal thickness increased from Group 1 to Group 3, but was not significant with the current sample size. There were no other differences between age groups.

Treatment of spontaneous chronic corneal epithelial defects (SCCEDs) with diamond burr debridement vs combination diamond burr debridement and superficial grid keratotomy.

OBJECTIVE: To evaluate the efficacy of diamond burr debridement (DBD) vs a combination of diamond burr debridement with superficial grid keratotomy (DBD+SGK) for the treatment of spontaneous chronic corneal epithelial defects (SCCEDs) in dogs. PROCEDURE: Medical records of dogs diagnosed with SCCEDs from three different institutions that received a DBD or DBD+SGK between 2003 and 2015 were reviewed. Age, breed, sex, history of a previous SCCED, procedures performed, time to healing, and complications were statistically analyzed. RESULTS: One hundred and ninety-four dogs met the inclusion criteria. Eighty-two of 106 eyes (77.4%) received a DBD and healed following the first treatment (13.3 ± 4.9 days to recheck, range 2-27). Sixty-eight of 88 eyes (77.3%) received a DBD+SGK and healed following the first treatment (15.4 ± 5.0 days to recheck, range 5-45). No significant difference in healing outcome was found between the two treatments (P = 1). For SCCEDs that healed after a single treatment (n = 150), complications occurred in 13.3% (n = 20) of eyes with no difference in complications between the DBD and DBD+SGK groups (P = .86). Thirty-five of 44 eyes (80.0%) healed after the second treatment (16 ± 8.2 days from second treatment to third visit, range 5-47); nine of 44 eyes (20.0%) were not healed (12 ± 6.2 days from second treatment to third visit, range 5-25). The second treatment method did not influence healing rates (P = .64). CONCLUSIONS: DBD and DBD+SGK are equally effective treatment methods for canine SCCEDs. No differences in complication rates after one treatment were observed between DBD and DBD+SGK.

Retinal detachment and glaucoma in the Boston Terrier and Shih Tzu following phacoemulsification (135 patients): 2000-2014.

OBJECTIVES: To report the cumulative incidence of retinal detachment (RD) and glaucoma following phacoemulsification in Boston Terriers and Shih Tzu in the southeastern United States over a 14-year period and investigate the potential predisposing risk factors. METHODS: Medical records of 83 Shih Tzu and 52 Boston Terriers that underwent phacoemulsification between 2000 and 2014, with or without intraocular lens placement, were reviewed. For a comparison population, phacoemulsification data from 45 Labrador Retrievers, 73 Schnauzers, and 159 Bichon Frises were evaluated. Information collected included signalment, concurrent systemic diseases, preoperative findings, surgical details, postoperative complications, and duration of follow-up. Percentages of patients to develop RD and glaucoma were assessed, as well as potential risk factors. Minimum of 3 months of follow-up after surgery was required for inclusion. RESULTS: Retinal detachment occurred in 7.7% (7/91 eyes) and 8.9% (11/123 eyes) and glaucoma occurred in 38.0% (35/91 eyes) and 29.3% (36/123 eyes) of Boston Terriers and Shih Tzu, respectively. Mean follow-up time was 804 days. Neither Boston Terriers nor Shih Tzu were at increased risk for RD or glaucoma when compared to the other breeds, and no significant risk factors for either breed were identified in the final multivariate analysis. CONCLUSIONS: The cumulative incidence of RD in Boston Terrier and Shih Tzu reported here was in agreement with previously reported nonbreed specific percentages (2.7-8.4%). The cumulative incidence of glaucoma in this population of Boston Terriers and Shih Tzu was higher than previously reported nonbreed specific percentages (5.1-18.8%).

Canine central corneal thickness measurements via Pentacam-HR® , optical coherence tomography (Optovue iVue® ), and high-resolution ultrasound biomicroscopy.

OBJECTIVE: To compare central corneal thickness (CCT) values in canine eyes using Pentacam-HR® Scheimpflug imaging (Pentacam), Optovue® iVue spectral-domain optical coherence tomography (SD-OCT), and high-resolution ultrasound biomicroscopy (UBM) and generate normative canine Pentacam CCT values. ANIMALS STUDIED: Twenty-four client-owned dogs (37 eyes) with nondiseased cornea(s) presenting to the Colorado State University Veterinary Teaching Hospital. PROCEDURES: Corneal images were acquired via Pentacam, SD-OCT, and UBM in the listed order. Machine-calculated values of CCT from Pentacam and SD-OCT were compared to operator-measured values from UBM. Bland-Altman analysis was performed to evaluate agreement between instruments. RESULTS: Mean CCT ± SD measured by Pentacam was 629.73 ± 64.57 µm, by SD-OCT was 610.56 ± 57.48 µm, and by UBM was 689.77 ± 55.93 µm. On average, Pentacam CCT was 19.17 ± 32.90 µm (3%) thicker than SD-OCT and 65.12 ± 44.52 µm (10.3%) thinner than UBM. SD-OCT was on average 82.47 µm (13.5% ) thinner than UBM. The 95% limits of agreement were (-45.31, 83.65), (-152.38, 22.13), and (-126.674, -38.270) for Pentacam vs. SD-OCT, Pentacam vs. UBM, and SD-OCT vs. UBM respectively. All differences were statistically significant (P < 0.01). CONCLUSIONS: Considering there is an average of 7.5% normal diurnal variation in canine CCT, a 3.0% difference between Pentacam and SD-OCT values is likely not clinically relevant. However, Pentacam measurements were both statistically and clinically significantly different from UBM and SD-OCT measurements.

Use of a nictitating membrane flap for treatment of feline acute corneal hydrops-21 eyes.

OBJECTIVE: To evaluate the effectiveness of the use of a nictitating membrane flap (NMF) as therapy in 19 cats (21 eyes) affected with feline acute corneal hydrops (FACH). METHODS: Medical records from 19 cats diagnosed with FACH and treated with a NMF were retrospectively evaluated. Information was collected from multiple veterinary hospitals and included signalment, medical history, therapy, and ocular outcome. RESULTS: Breeds included 13 Domestic Shorthairs, 2 Exotic Shorthairs, 2 Maine Coons, 1 Persian, and 1 Domestic Medium Hair. Two cats were bilaterally affected. Median age of cats was 3.2 years (range 0.26-15 years). Eleven patients were spayed females, 6 were neutered males, and 2 were intact males. Topical steroids were previously administered in 5 (23.8%) eyes; oral steroids were previously administered in 7 cats (36.8% of patients); three patients received both oral and topical steroids. Thirteen of 21 (61.9%) eyes had a history of ocular disease including ulcerative and nonulcerative keratitis, anterior uveitis, corneal sequestrum, conjunctivitis, and glaucoma. Median duration of NMF was 15 days (range 6-30 days). Follow-up ranged from 12 to 1601 days (median 169 days). Corneal perforation occurred in 1 (4.7%) eye and was successfully repaired. One lesion (4.7%) in a diabetic patient did not resolve. Nineteen of the treated eyes (90.5%) resolved with no complications. CONCLUSIONS: A nictitating membrane flap successfully treated 90.5% of FACH eyes (89.5% of patients).