Quantifying refractive error in companion dogs with and without nuclear sclerosis: 229 eyes from 118 dogs.

OBJECTIVE: To evaluate the relationship between nuclear sclerosis (NS) and refractive error in companion dogs. ANIMALS STUDIED: One hundred and eighteen companion dogs. PROCEDURES: Dogs were examined and found to be free of significant ocular abnormalities aside from NS. NS was graded from 0 (absent) to 3 (severe) using a scale developed by the investigators. Manual refraction was performed. The effect of NS grade on refractive error was measured using a linear mixed effects analysis adjusted for age. The proportion of eyes with >1.5 D myopia in each NS grade was evaluated using a chi-square test. Visual impairment score (VIS) was obtained for a subset of dogs and compared against age, refractive error, and NS grade. RESULTS: Age was strongly correlated with NS grade (p < .0001). Age-adjusted analysis of NS grade relative to refraction showed a mild but not statistically significant increase in myopia with increasing NS grade, with eyes with grade 3 NS averaging 0.58-0.88 D greater myopia than eyes without NS. However, the myopia of >1.5 D was documented in 4/58 (6.9%) eyes with grade 0 NS, 12/91 (13.2%) eyes with grade 1 NS, 13/57 (22.8%) eyes with grade 2 NS, and 7/23 (30.4%) eyes with grade 3 NS. Risk of myopia >1.5 D was significantly associated with increasing NS grade (p = .02). VIS was associated weakly with refractive error, moderately with age, and significantly with NS grade. CONCLUSIONS: NS is associated with visual deficits in some dogs but is only weakly associated with myopia. More work is needed to characterize vision in aging dogs.

Relative ability of aqueous humor from dogs with and without primary angle-closure glaucoma and ADAMTS10 open-angle glaucoma to catalyze or inhibit collagenolysis.

OBJECTIVE: The objective of the study was to compare the ability of aqueous humor (AH) from dogs with primary angle-closure glaucoma (CPACG), companion dogs without overt evidence of CPACG, and Beagles with and without ADAMTS10 open-angle glaucoma (ADAMTS10-OAG) to catalyze or inhibit collagenolysis. ANIMALS STUDIED: Seventeen normal pet dogs, 27 dogs with CPACG, 19 Beagles with ADAMTS10-OAG, and 4 unaffected Beagles. PROCEDURES: A fluorescein-based substrate degradation assay was used to assess AH proteolytic capacity. Samples were then assayed using the same substrate degradation assay, with recombinant activated matrix metalloproteinase-2 (MMP-2) added to measure protease inhibition effects. RESULTS: For the protease activity assay, relative fluorescence (RF) for AH from normal pet dogs was 13.28 ± 2.25% of control collagenase while RF for AH from dogs with CPACG was 17.47 ± 4.67%; RF was 8.57 ± 1.72% for ADAMTS10-OAG Beagles and 7.99 ± 1.15% for unaffected Beagles. For the MMP-2 inhibition assay, RF for AH from normal dogs was 34.96 ± 15.04% compared to MMP-2 controls, while RF from dogs with CPACG was 16.69 ± 7.95%; RF was 85.85 ± 13.23% for Beagles with ADAMTS10-OAG and 94.51 ± 8.36% for unaffected Beagles. Significant differences were found between dogs with CPACG and both normal pet dogs and dogs with ADAMTS10-OAG and between normal pet dogs and both groups of Beagles. CONCLUSIONS: AH from dogs with CPACG is significantly more able to catalyze proteolysis and inhibit MMP-2 than AH from normal dogs or dogs with ADAMTS10-OAG. Results suggest that pathogenesis may differ between CPACG and ADAMTS10-OAG.

Retrospective evaluation of canine primary, multicentric, and metastatic intraocular neoplasia.

OBJECTIVE: To provide an updated characterization of the prevalence of primary, multicentric, and metastatic intraocular tumors in the canine patient. PROCEDURES: Medical records databases from 4 veterinary referral hospitals were reviewed from 1999 to present to identify dogs with a diagnosis of intraocular neoplasia histopathologically confirmed following enucleation or necropsy. RESULTS: One hundred seventy-two dogs with 173 intraocular neoplasms met the inclusion criteria. Primary intraocular neoplasms were the most common tumors in the study (128); the two most common types were melanocytic neoplasia (90), followed by iridociliary neoplasia (33). There were 28 cases of intraocular involvement secondary to round cell neoplasia, with 18 cases of lymphoma, seven histiocytic sarcomas, and three undifferentiated round cell neoplasms. There were 17 cases of metastatic intraocular neoplasia, with hemangiosarcoma being the most common (9). CONCLUSIONS: The majority of intraocular tumors in dogs arise from the ocular tissues. However, the eye may also be involved in patients with multicentric neoplasia, and, less commonly, as a site for metastatic disease. Ocular screening for patients with multicentric neoplasia should be considered during staging, and ocular signs should be viewed with suspicion in dogs with neoplasia in other sites.

Comparative effects of latanoprost and latanoprostene bunod on intraocular pressure and pupil size in ophthalmologically normal Beagle dogs.

OBJECTIVE: To compare effects of latanoprost, a topical prostaglandin analogue (PGA) commonly used to treat glaucoma and lens instability in dogs, and latanoprostene bunod, a novel PGA with a nitric oxide-donating moiety, on intraocular pressure (IOP) and pupil diameter (PD). ANIMALS STUDIED: Ten ophthalmologically normal Beagle dogs. PROCEDURES: Dogs were treated twice a day for 5 days in a randomly selected eye with either latanoprost or latanoprostene bunod. After a 6-week washout period, dogs were treated with the opposite drug. IOP and PD were measured at treatment times, at midday on days 1 and 5, and for 6 days post-treatment. RESULTS: Both drugs significantly decreased IOP and PD. At midday on day 5 of treatment, mean IOP in eyes treated with latanoprost was 4.5 mmHg lower than the fellow eye and 3.0 mmHg lower than the same eye at baseline, while mean IOP in eyes treated with latanoprostene bunod was 5.5 mmHg lower than the fellow eye and 3.6 mmHg lower than baseline. Mean PD was 0.94 mm in eyes treated with latanoprost and 0.76 mmHg in eyes treated with latanoprostene bunod. There was no significant difference between the two drugs for either parameter at that time point (p = .372 and .619, respectively, for IOP relative to control and to baseline; p = .076 for PD) or when analyzed longitudinally. Significant diurnal variation in PD was noted and may have implications for treatment of lens' instability. CONCLUSIONS: Latanoprost and latanoprostene bunod produce similar IOP reduction and miosis in normal canine eyes.

Unilateral eosinophilic cellulitis leading to implant extrusion after bilateral enucleation in a dog.

A mixed breed dog underwent bilateral enucleation with orbital implant placement for secondary glaucoma. Subsequent unilateral implant extrusion occurred. An orbital mass histologically consistent with eosinophilic cellulitis was discovered. It may have developed secondary to communication between orbit and skin. Inflammatory processes mimicking neoplasia can cause implant loss post-enucleation.

Patterns of bacterial culture and antimicrobial susceptibility test results for dogs with retrobulbar abscesses: 133 cases (2002-2019).

OBJECTIVE: To evaluate patterns of bacterial culture and antimicrobial susceptibility test results for dogs with retrobulbar abscesses and generate recommendations for empirical antimicrobial selection. ANIMALS: 133 dogs examined between 2002 and 2019. PROCEDURES: Records were retrospectively reviewed to determine type of bacterial culture, number and type of bacterial isolates, antimicrobial susceptibility test results, concurrent and recent antimicrobial exposure, effect of culture results on antimicrobial regimen, and outcome. RESULTS: Aerobic culture alone was performed in 37 dogs, and aerobic and anaerobic culture was performed in 96 dogs. Isolates were recovered from 96 dogs, with multiple isolates recovered from 54 (56%) of those dogs. Of the 69 dogs for which both aerobic and anaerobic culture was performed and at least 1 isolate was obtained, 34 (49%) had purely aerobic infections, 15 (22%) had mixed aerobic and anaerobic infections, and 20 (29%) had purely anaerobic infections. Pasteurella spp (n = 26), Streptococcus spp (20), and Escherichia coli (12) were the most common aerobic isolates. Bacteroides spp (n = 22), Actinomyces spp (10), and Fusobacterium (10) spp were the most common anaerobic isolates. Susceptibility test results led to changes in the antimicrobial regimen in 37 of 80 (46%) dogs. Of the 76 dogs for which outcome information was available, 78 (97%) recovered. CLINICAL RELEVANCE: Multipathogen and anaerobic infections were common in dogs with retrobulbar abscesses. Susceptibility data supported the use of amoxicillin-clavulanate or a combination of clindamycin and enrofloxacin as first-line treatments. Additional study is needed to characterize anaerobic antimicrobial susceptibilities and to compare results of susceptibility testing with in vivo responses to antimicrobial administration.

Evaluation of matrix metalloproteinases and tissue inhibitors of metalloproteinases in aqueous humor of dogs with versus without naturally occurring primary angle-closure glaucoma.

OBJECTIVE: To compare concentrations of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) in aqueous humor from ophthalmologically normal dogs and dogs with naturally occurring primary angle-closure glaucoma (cPACG). SAMPLE: Aqueous humor samples from 12 eyes with cPACG and 18 ophthalmologically normal eyes of dogs. PROCEDURES: A multiplex fluorescence-based ELISA was used to measure concentrations of MMP-1, MMP-2, MMP-3, MMP-8, MMP-9, MMP-10, MMP-13, TIMP-1, TIMP-2, and TIMP-4. Results for eyes with versus without cPACG were compared. RESULTS: Significantly higher mean concentrations of MMP-1 (45% higher), MMP-2 (55% higher), MMP-3 (39% higher), MMP-8 (79% higher), MMP-9 (29% higher), MMP-10 (60% higher), TIMP-1 (63% higher), and TIMP-2 (136% higher) were detected in aqueous humor from eyes with cPACG, compared with ophthalmologically normal eyes. CLINICAL RELEVANCE: MMPs and TIMPs have pivotal roles in extracellular matrix turnover and homeostasis in the outflow pathways of the eye. Results of the present study documented higher concentrations of MMPs and TIMPs in aqueous humor samples from dog eyes with late-stage cPACG. Although, to our knowledge, TIMPs have not previously been evaluated in the context of cPACG, the markedly higher concentration of TIMPs in eyes with cPACG suggested that inhibition of proteolysis and extracellular matrix turnover might be a factor in the development of glaucoma in susceptible individuals. However, because the present study used samples from dogs with late-stage cPACG, further work is required to characterize the temporal relationship between MMP and TIMP concentration changes and onset or progression of disease.

Duration of Mydriasis Produced by 0.5% and 1% Tropicamide in Sprague-Dawley Rats.

Ophthalmic examination (OE) is a common part of preclinical studies. Pupillary dilation to facilitate OE may affect results of other planned testing. The purpose of this study was to determine the duration of mydriasis produced by commercially available 0.5% and 1% tropicamide in ophthalmologically normal albino rats. Twelve female Sprague-Dawley rats were used. A single drop of 1% tropicamide was applied to one eye of each rat. A single drop of balanced salt solution (BSS) was applied to the contralateral eye. Measurements of pupillary diameter (PD) were obtained using a digital caliper at 0, 20, 40, 60, 120, 180, 240, 300, and 360 min after application. After a 3-wk washout period, the procedure was repeated using 0.5% tropicamide. Pupillary dilation sufficient to allow posterior segment evaluation was achieved with 0.5% and 1% tropicamide. Maximum PD after treatment with 0.5% tropicamide was 4.17 ± 0.22 mm at 40 min; maximum PD after treatment with 1% tropicamide was not significantly different (4.28 mm at both 20 and 40 min (±0.43 mm and 0.23 mm, respectively)). Mean PD remained above 3.5 mm in treated eyes for 60 min. In eyes treated with 0.5% tropicamide, mean PD was significantly different from baseline mean PD for that eye up to 300 min. In eyes treated with 1% tropicamide, mean PD was significantly different than baseline mean PD for that eye at all timepoints. Both concentrations of tropicamide produced a transient mild to moderate mydriasis in the contralateral eye. Duration of action is at least 5 h for 0.5% tropicamide and 6 h for 1% tropicamide. Results of this study support use of 0.5% tropicamide for OE in albino rats, with administration performed no more than 60 min prior to examination.

Outcomes Following Transcorneal Diode Laser Ablation of Uveal Cysts: 48 Horses (2006-2020).

Uveal cysts can lead to undesirable behaviors and poor performance in horses. Transcorneal laser ablation has been proposed as a safe and effective treatment for uveal cysts suspected of causing behavioral changes but outcomes have been reported in only a small number of horses. In this retrospective study, records were identified for horses who had undergone transcorneal cyst ablation using a diode laser. Information was collected regarding signalment, behavioral or performance issues reported prior to the procedure, and complications. Owners were contacted to provide follow-up information regarding resolution of behavioral issues. Seventy eyes from 48 horses were treated. Undesirable behaviors or performance issues were reported prior to the procedure in 35 horses, and follow-up information was provided for 22 of those horses. Of these 22 horses, 59% of owners reported significant improvements in behavior or performance, 27% reported some improvement, and 14% reported no improvement. No significant complications were reported in association with the procedure. Although follow-up data were available for only a subset of horses, transcorneal diode laser ablation was an effective means of resolving owner-reported behavioral or performance complaints believed to be caused by uveal cysts for many of the horses in this group. Further work is needed to assess effects of uveal cysts on equine behavior and to characterize effects of transcorneal diode laser ablation prospectively.

Iatrogenic ocular trauma associated with infraorbital block performed for rhinoscopy in a cat: case report and preliminary imaging findings.

OBJECTIVES: This paper describes a case of endophthalmitis in a feline patient caused by globe penetration during an infraorbital block performed to provide analgesia during rhinoscopy, and presents additional imaging and dissection data demonstrating risk of iatrogenic ocular trauma during infraorbital blocks in cats when the infraorbital canal is entered. METHODS: Case records and accompanying histopathologic reports were reviewed for the feline patient. Separately, two feline cadavers were imaged using CT following placement of 5/8" 25 G needles or 1" 22 G over the needle catheters in the infraorbital canal. Infraorbital blocks with injection of trypan blue dye followed by dissection were performed in two further feline cadavers to assess the potential for globe penetration and to provide preliminary information regarding the potential efficacy of infraorbital blocks for analgesia during rhinoscopy. RESULTS: Clinical and histopathologic findings support inadvertent globe penetration during infraorbital block as the cause for endophthalmitis in the feline patient described. CT imaging and dye injection studies further demonstrate the risks involved with this local anesthetic technique in cats. CONCLUSIONS AND RELEVANCE: Further study is needed to assess the safety and efficacy of infraorbital blocks performed for rhinoscopy in cats. Catheters may be safer anesthetic delivery devices than needles. Extreme caution should be used when entering the infraorbital canal in cats.

Evaluation of cytology and histopathology for the diagnosis of feline orbital neoplasia: 81 cases (2004-2019) and review of the literature.

OBJECTIVE: To provide an updated overview of feline orbital neoplasia, to compare diagnostic utility of cytology and histopathology, and to evaluate minimally invasive sampling modalities. PROCEDURES: A medical records search was performed to identify cats with orbital neoplasia. Data were collected regarding signalment, diagnosis, vision status, imaging modalities, and sample collection methods. A reference population with orbital neoplasia was also identified via literature search for comparison with regard to final diagnosis. RESULTS: Eighty-one cats met selection criteria and 140 cases were identified in the literature. In the study and reference populations, respectively, diagnoses were grouped as follows: round cell tumors 47% and 24%, epithelial tumors 38% and 40%, mesenchymal tumors 14% and 34%, and neurologic origin tumors 1% and 2%. The most common diagnoses in both groups were lymphoma and squamous cell carcinoma (SCC). Feline restrictive orbital myofibroblastic sarcoma (FROMS) was common in the reference population but not diagnosed in the study population. Cytology results were available for 41 cats; histopathology results were available for 65 cats. Both cytology and histopathology results were available for 25 cats, in 44% of which cytologic results were overturned. No significant complications were associated with any sampling method. Lack of cats with multiple samples available for histopathology limited comparison between tissue sampling methods. CONCLUSIONS: Orbital neoplasia is common in cats, with round cell and epithelial tumors diagnosed most commonly in the study population. Histopathology is superior to cytology in providing a definitive diagnosis. Minimally invasive tissue biopsy techniques appear to be safe and effective.

Evaluation of cytology and histopathology for the diagnosis of canine orbital neoplasia: 112 cases (2004-2019) and review of the literature.

OBJECTIVE: To provide an updated overview of canine orbital neoplasia, to compare diagnostic utility of cytology and histopathology, and to evaluate alternative sampling modalities, particularly image-guided core needle biopsy. PROCEDURES: A medical records search was performed to identify dogs with orbital neoplasia. Data were collected regarding signalment, diagnosis, vision status, imaging modalities, and sample collection methods. A reference population with orbital neoplasia was also identified via literature search for comparison with regard to final diagnosis. RESULTS: One hundred and twelve dogs met selection criteria. In the study and reference populations, respectively, diagnoses were grouped as follows: mesenchymal tumors 40% and 35%, epithelial tumors 35% and 18%, tumors of neural origin 8% and 37%, and round cell 17% and 10%. The most common diagnoses in the study group were nasal adenocarcinoma, osteosarcoma, lymphoma, and meningioma. Cytology results were available for 47 dogs and histopathology results were available for 95 dogs. Both cytology and histopathology results were available for 30 dogs, in 53% of which results were discordant. Cytology samples were nondiagnostic or provided a diagnosis that was later overturned in 32% of cases in which they were obtained. Results from core needle biopsy samples were nondiagnostic or overturned by surgical biopsy results in only 13% of cases. No significant complications were associated with any sampling method. CONCLUSIONS: Orbital neoplasia is common in dogs. Histopathology is superior to cytology in providing a definitive diagnosis. Image-guided core needle biopsy appears to be a safe and effective means of obtaining samples.

Use of cyanoacrylate adhesive in the surgical management of feline corneal sequestrum: 16 cases (2011-2018).

OBJECTIVE: To evaluate the use of cyanoacrylate adhesive as an adjunct to lamellar keratectomy in cats with corneal sequestrum. METHODS: Medical records were reviewed to identify cats with naturally occurring midstromal corneal sequestra treated with lamellar keratectomy and cyanoacrylate adhesive. All cats also had a bandage contact lens placed for postoperative comfort. Data collected included breed, age, sex, and reproductive status of the cat, eye involved, presence or absence of neovascularization at the time of surgery, history of prior sequestra, additional ocular procedures performed, use of neuromuscular blocking agents, procedure time, time to cessation of topical medications, time to recurrence or last follow-up, and complications aside from recurrence. RESULTS: Sixteen cats met study criteria, with a median follow-up time of 17.5 months in those without recurrence. Median time to cessation of topical medications was 4 weeks. Fourteen cats (87%) have not experienced recurrence. Other than recurrence in two cats, no significant complications were noted. Aside from purebred status, no commonalities were found between the two cats with recurrence. Neuromuscular blocking agents were not used during surgery in most cases. Median procedure time was 10 minutes. CONCLUSIONS: Cyanoacrylate adhesive is an effective and safe alternative to grafting procedures in cats undergoing lamellar keratectomy for treatment of corneal sequestrum. Recurrence rates are comparable to those seen with grafting techniques. Benefits of this approach include decreased anesthesia time, lower procedure costs, and short duration of postoperative treatment.

Western blot patterns of serum autoantibodies against optic nerve antigens in dogs with goniodysgenesis-related glaucoma.

OBJECTIVE: To investigate whether differences existed between clinically normal dogs and dogs with goniodysgenesis-related glaucoma (GDRG) in serum autoantibodies against optic nerve antigens. ANIMALS: 16 dogs with GDRG, 17 healthy dogs with unremarkable pectinate ligament and iridocorneal angle morphology, and 13 euthanized dogs with no major ocular abnormalities or underlying diseases. PROCEDURES: Western blotting was performed with optic nerve extracts from the euthanized dogs as an antigen source and serum from clinically normal dogs and dogs with GDRG as a primary antibody (autoantibody) source. Blots were evaluated for presence and density of bands. RESULTS: Multiple bands were identified on western blots from all dogs with GDRG and all clinically normal dogs, with a high degree of variability among individual dogs. Dogs with GDRG were significantly more likely than healthy dogs to have bands present at 38, 40, and 68 kDa. Dogs with GDRG had significant increases in autoreactivity at 40 and 53 kDa and a significant decrease in autoreactivity at 48 kDa. CONCLUSIONS AND CLINICAL RELEVANCE: Significant differences in serum autoantibodies against optic nerve antigens were found in dogs with versus without GDRG. Although it remains unclear whether these differences were part of the pathogenesis of disease or were sequelae to glaucomatous changes, these findings provide support for the hypothesis that immune-mediated mechanisms play a role in the development or progression of GDRG. However, the high degree of variability among individual dogs and the considerable overlap between groups suggest that the clinical usefulness of this technique for distinguishing dogs with GDRG from clinically normal dogs is likely limited.

Glaucoma associated with uveal cysts and goniodysgenesis in American Bulldogs: a case series.

We present a series of three American Bulldogs with clinical signs of glaucoma and intraocular inflammation accompanied by bilateral uveal cysts and abnormal gonioscopic findings. All dogs proved refractory to medical management and were enucleated. Histopathologic findings were similar in all three and included significant preiridal fibrovascular membranes and mononuclear inflammatory infiltrates in the anterior uvea. On microscopic evaluation, cysts appeared to arise primarily from the ciliary body and iridociliary sulcus, with smaller cysts also budding from the posterior iris. Pigment dispersion was variable but consistent, involving deposition of a small number of pigment-laden cells in the dependent trabecular meshwork. Cataract formation was not noted. Glaucoma associated with uveal cysts has been described previously in Golden Retrievers and Great Danes, although clinical and histopathologic findings in those breeds are not identical to those described here. American Bulldogs with uveal cysts should have gonioscopy performed and should be monitored carefully for signs of increased intraocular pressure and intraocular inflammation. Furthermore, documentation of cyst-associated glaucoma in a third breed suggests clinicians should exercise caution in dismissing uveal cysts in dogs as incidental findings.

Reactive histiocytosis of the orbit and posterior segment in a dog.

We present a case of reactive histiocytic disease involving the orbit, optic nerve, retina, and choroid in a Border Collie dog initially presenting for vision loss. Long-term partial return of vision has been achieved with systemic immunosuppression. Anterior segment and ocular surface manifestations of reactive histiocytic disease in dogs are relatively common. Posterior segment and orbital involvement, however, are minimally documented in the existing literature. To the authors' knowledge, this is the first report of disease confined to the orbit and posterior segment as well as the first report of vision loss as a presenting complaint for reactive histiocytic disease. Clinical, magnetic resonance imaging, cytologic, and histopathologic findings are reviewed.

Uveitis associated with septic peritonitis in a cat.

OBJECTIVE: To report a case of bilateral uveitis believed to be a consequence of septic peritonitis in a 19-month-old cat. CASE SUMMARY: Bilateral anterior uveitis with suspicion of extension to the posterior segment was documented in a previously healthy young cat during hospitalization for severe septic peritonitis. Based on medical history and other findings uveitis was believed to result from concurrent abdominal sepsis, due either to metastatic seeding of bacterial organisms or to effects of bacterial toxins and inflammatory mediators on the blood-aqueous barrier. The cat was surgically and medically managed, and made a full recovery with respect to both his ocular and his abdominal disease. NEW OR UNIQUE INFORMATION PROVIDED: Ocular complications secondary to systemic sepsis are well documented in people but seldom reported in the veterinary literature. To the authors' knowledge this is the first report of uveitis linked to septic peritonitis in any veterinary species and the first to report sepsis-related uveitis in a cat. Ocular inflammatory disease in the context of critical illness deserves attention as a potential significant source of morbidity. The development of ocular inflammatory disease may serve as a sentinel lesion for systemic sepsis and other life-threatening conditions.

360-degree conjunctival grafting for management of diffuse keratomalacia in a dog.

We present a report describing use of a 360-degree conjunctival graft for management of progressive keratomalacia refractory to medical treatment in a 5-month-old American Cocker Spaniel. In the dog of this report, the extension of melting to nearly the entire corneal surface limited surgical options. Following surgery and later resection of the graft, the patient is visual with minimal corneal opacity. Numerous corneal grafting techniques have been described in companion animals, but require special materials and may not be possible when melting is extensive. Although older animals or animals with additional corneal pathology may have less ideal outcomes in terms of corneal clarity than the patient of this report, we believe that 360-degree conjunctival grafting offers a viable and cost-effective option for management of cases with extensive keratomalacia that may otherwise have resulted in enucleation.