Clinical applications of in vivo confocal microscopy enhance the detection and management of ocular surface disease in dogs and cats.

In vivo confocal microscopy (IVCM) is a unique imaging technique that permits noninvasive evaluation of the ocular surface on the cellular level. High-resolution images of all layers of the cornea are obtained in real-time with IVCM, and the acquired images are often comparable to ex vivo histochemical analysis of corneal biopsy specimens. The basic morphological features of the healthy living cornea as viewed by IVCM are reported in many domestic animal species, and the number of published descriptions of ocular surface pathologies in companion animals is progressively expanding. There is great potential for IVCM to improve the detection, characterization, and management of diverse ocular surface diseases in companion animals. This review summarizes several established and emerging clinical applications of IVCM in companion animal ocular surface disease, including infectious keratitis, corneal foreign bodies, corneal dystrophies and degenerations, ocular surface masses, corneal endotheliitis, pigmentary keratitis, and evaluation of corneal nerves.

Breed predispositions to congenital and juvenile cataracts in horses at two academic institutions.

BACKGROUND: Determination of horse breeds predisposed to congenital and juvenile cataracts will enable investigations into potential genetic mechanisms for cataracts in horses. OBJECTIVE: To investigate horse breed predispositions to congenital and juvenile cataracts in two academic referral populations. STUDY DESIGN: Retrospective case series. METHODS: Medical record identification of horses diagnosed with congenital or juvenile cataracts at the Cornell University Equine Hospital (2000-2022) and the University of California-Davis (UCD) Large Animal Clinic (1990-2021). Signalment, examination findings and treatments were recorded. Descriptive statistics were performed, and breed over-representations were determined using Chi-squared or Fisher's exact tests. RESULTS: Thirty-one (Cornell) and 70 (UCD) horses with congenital or juvenile cataracts were identified, for a total of 101 affected horses. Seventy-eight horses were affected bilaterally and 23 were affected unilaterally, for a total of 179 affected eyes. Standardbreds were significantly over-represented at both institutions, comprising 32.5% of congenital/juvenile cataract cases and 10% of the equine hospital population at Cornell (p < 0.001) and 4.3% of cataract cases and 1.3% of the equine hospital population at UCD (p = 0.03). Thoroughbreds were under-represented for congenital and juvenile cataracts at both institutions (p = 0.03 Cornell, p = 0.01 UCD). MAIN LIMITATIONS: Retrospective study, potential for selection bias. CONCLUSIONS: The over-representation of the Standardbred breed for congenital and juvenile cataracts at two institutions suggests an underlying genetic basis in the breed. Future genetic and genomic studies are warranted to investigate heritable cataracts in Standardbred horses.

Macrodendritic ulcerative keratitis and conjunctival lymphoid hyperplasia in horses with equine herpesvirus-2 and equine herpesvirus-5 infections.

OBJECTIVE: The aim of this study was to describe the clinical, confocal microscopic, histologic, and virologic features of horses with macrodendritic ulcerative keratitis and conjunctival lymphoid hyperplasia associated with equine herpesvirus-2 and equine herpesvirus-5 infection. ANIMAL STUDIED: Four foals with bilateral ocular disease. PROCEDURES: Complete ophthalmic examination was performed for each horse, and corneal samples were collected for cytology and microbiologic evaluation, including virus isolation and molecular diagnostics for the equine herpesviruses. In vivo confocal microscopy examination of the cornea was performed in two horses. Conjunctival biopsies for histopathology were collected from two horses with nodular conjunctival thickening. RESULTS: Each horse had bilateral, large, superficial dendritic corneal ulcerations that covered extensive regions of the corneal surface. Corneal in vivo confocal microscopy examination in two horses detected inflammatory cells and populations of morphologically abnormal corneal epithelial cells adjacent to the ulcerations. The abnormal epithelial cells included round, relatively small, hyperreflective cells intermixed with elongated, enlarged, hyperreflective cells. Equine herpesvirus-2 was isolated from corneal samples of 2 horses and detected by PCR assay in the other two horses. Equine herpesvirus-5 was also detected by PCR assay in three of the horses. Conjunctival histopathology identified predominantly lymphocytic infiltrates. The macrodendrites and conjunctival masses resolved with topical antiviral therapy (cidofovir or idoxuridine) in all horses and did not recur. CONCLUSIONS AND CLINICAL RELEVANCE: The equine gammaherpesviruses may be associated with the development of macrodendritic ulcerative keratitis and conjunctival lymphocytic masses in foals. In vivo confocal microscopy of horses with macrodendrites revealed similar findings to other host species with herpetic dendritic keratitis.

Experimental Induction of Acute Acanthamoeba castellanii Keratitis in Cats.

Purpose: To develop a feline model of acute Acanthamoeba keratitis using methods that replicate natural routes of infection transmission. Methods: Corneal Acanthamoeba castellanii inoculation was performed by three methods: topical inoculation with Acanthamoeba solution following corneal abrasion, placement of a contaminated contact lens for 7 days, and placement of a contaminated contact lens for 7 days following corneal abrasion. Sham inoculations with parasite-free medium and sterile contact lenses were also performed. Cats were monitored by ocular examination and in vivo corneal confocal microscopy for 21 days post-inoculation. Corneal samples were collected at intervals for microbiologic assessment, histopathology, and immunohistochemistry. Results: All cats in the corneal abrasion groups developed clinical keratitis. Clinical ocular disease was inconsistently detected in cats from the contaminated contact lens only group. Initial corneal lesions were characterized by multifocal epithelial leukocyte infiltrates. Ocular lesions progressed to corneal epithelial ulceration and diffuse stromal inflammation. After 14 days, corneal ulcerations resolved, and stromal inflammation consolidated into multifocal subepithelial and stromal infiltrates. Corneal amoebae were detected by culture, in vivo confocal microscopy, histopathology, and immunohistochemistry in cats with keratitis. Neutrophilic and lymphocytic keratoconjunctivitis with lymphoplasmacytic anterior uveitis were identified by histopathology. Coinfection with aerobic bacteria was detected in some, but not all, cats with keratitis. Ocular disease was not detected in the sham inoculation groups. Conclusions: Feline Acanthamoeba keratitis is experimentally transmissible by contaminated contact lenses and topical inoculation following corneal epithelial trauma. Translational Relevance: Experimentally induced acute Acanthamoeba keratitis in cats is clinically and histopathologically similar to its human counterpart.

Decreased corneal subbasal nerve fiber length and density in diabetic dogs with cataracts using in vivo confocal microscopy.

OBJECTIVE: To determine whether there is a difference in corneal sensitivity and corneal subbasal nerve plexus (CSNP) morphology in cataractous dogs with diabetes mellitus (DM) versus without DM. ANIMALS STUDIED: Twenty six domestic dogs with cataracts of various breeds presented for phacoemulsification, 13 with DM and 13 without DM. PROCEDURE: The inclusion criteria for the study were dogs with bilateral cataracts and no clinical evidence of corneal disease. The diabetic group had documented hyperglycemia and was currently treated with insulin. The non-diabetic group had no evidence of DM on examination and bloodwork. Complete ophthalmic examination, corneal esthesiometry, and in vivo confocal microscopy of the CSNP was performed for both eyes of each dog. The CSNP was evaluated using a semi-automated program and statistically analyzed. RESULTS: The mean (±SD) CSNP fiber length was significantly decreased in diabetic (3.8 ± 3.0 mm/mm2 ) versus non-diabetic (6.7 ± 1.9 mm/mm2 ) dogs. Likewise, the mean (±SD) fiber density was significantly decreased in diabetic (8.3 ± 3.1 fibers/mm2 ) versus non-diabetic (15.5 ± 4.9 fibers/mm2 ) dogs. The corneal touch threshold was significantly reduced in diabetic (2.1 ± 0.8 cm) versus non-diabetic (2.8 ± 0.4 cm) dogs. There was a non-significant trend towards subclinical keratitis in diabetic (9/13) versus non-diabetic (4/13) dogs. CONCLUSIONS: Morphological and functional abnormalities of the CSNP were present in dogs with DM, including decreased fiber length, fiber density, and corneal sensitivity. These findings are consistent with diabetic neuropathy and could contribute to clinically significant corneal complications after cataract surgery.

IN VIVO CONFOCAL MICROSCOPY FOR CHARACTERIZATION OF MYCOTIC KERATITIS IN OWLS (BUBO SCANDIACUS, STRIX VARIA) AND A WOODCOCK (SCOLOPAX MINOR): THREE CASES.

This case series describes the use of in vivo confocal microscopy in the diagnosis and treatment of mycotic keratitis in two owls (one Bubo scandiacus, one Strix varia) and one woodcock (Scolopax minor). Each bird was at increased risk of fungal infection due to recent injury or stress. Ophthalmic findings in all birds included blepharospasm, ocular discharge, ulcerative keratitis, white or yellow corneal plaques, and anterior uveitis. Fungal hyphae were identified in corneal samples from all three eyes examined cytologically and in all three eyes by using in vivo confocal microscopy. Aspergillus fumigatus was isolated from a corneal culture in one bird. Despite medical treatment, progressive ocular disease prompted enucleation in two birds. Fungal hyphae were detected by histopathology in one of the two enucleated eyes. In vivo confocal microscopy aided the diagnosis of fungal keratitis in all birds and was the only diagnostic method that allowed immediate, real-time quantification of the extent (area and depth) and severity of mycotic keratitis.

Nocardia and Streptomyces keratitis in dogs: In vivo detection of filamentous bacteria by confocal microscopy.

OBJECTIVE: To describe the clinical features of dogs with Nocardia and Streptomyces keratitis, including the results of in vivo confocal microscopy examinations. ANIMAL STUDIED: A 15-year-old, male-castrated, miniature Schnauzer was presented with a multilobulated, cystic, pink, ulcerated corneal mass with surrounding dense leukocyte infiltrates. Cytologic evaluation of a corneal scraping identified pyogranulomatous inflammation and filamentous bacteria. Nocardia nova was cultured from corneal samples. Anterior lamellar keratectomy was performed to excise the affected corneal region and histopathologic evaluation confirmed the diagnosis of pyogranulomatous keratitis. A 10-year-old, male-castrated, Yorkshire terrier was presented for evaluation of a chronic anterior stromal corneal ulcer associated with a brown corneal plaque. Cytologic evaluation of a corneal scraping identified suppurative inflammation and filamentous bacteria. A Streptomyces sp. was cultured from corneal samples. The keratitis in both dogs resolved with therapy. PROCEDURES: In vivo confocal microscopy examination of the corneal lesions in both dogs revealed dense accumulations of leukocytes and clusters of hyperreflective, slender, branching bacterial structures that were approximately 1.5-2.0 µm in diameter and 25-50 µm in length. Confocal microscopy imaging of the Nocardia isolate in vitro, and ex vivo canine corneas experimentally infected with the bacteria, was performed to corroborate the in vivo findings. The morphology of the filamentous bacteria was similar between the in vivo, in vitro, and ex vivo confocal microscopy examinations. CONCLUSIONS AND CLINICAL RELEVANCE: Nocardia and Streptomyces spp. can be associated with infectious keratitis in dogs. In vivo detection of filamentous bacteria in the cornea can be accomplished by confocal microscopy.

Susceptibility of the Intact and Traumatized Feline Cornea to In Vitro Binding and Invasion by Acanthamoeba castellanii.

PURPOSE: Acanthamoeba castellanii ( A. castellanii ) displays host specificity at the level of the ocular surface. This study determined the susceptibility of the intact and traumatized feline cornea to A. castellanii binding and invasion relative to other host species with established susceptibility and resistance to Acanthamoeba binding. METHODS: Full-thickness buttons of fresh feline, porcine, and canine corneas were prepared. The corneal epithelium was confirmed intact by fluorescein staining or lightly scarified with a 25-G needle to simulate corneal trauma. Acanthamoeba castellanii was axenically cultivated. Corneal buttons were incubated with the parasite suspension or parasite-free medium for 18 hours at 35°C. Corneal buttons were rinsed, fixed, and processed for histopathology and immunohistochemistry using immunoperoxidase and immunofluorescence methods of amoeba detection. RESULTS: Numerous amoebae were bound to feline and porcine corneas incubated with parasites. In both intact and traumatized corneas, amoebae were detected at all levels in the corneal epithelium and within the anterior stroma. In traumatized corneal sections, amoebae were frequently present in regions of epithelial damage. Corneal architecture was well-preserved in sections incubated with parasite-free medium; however, epithelial cell sloughing, separation of epithelial layers, and epithelial detachment from the stroma were observed in corneas incubated with amoebae. Intact and traumatized canine corneas were relatively free of adherent amoebae, and corneal architecture was indistinguishable between sections incubated with the parasite suspension and parasite-free medium. CONCLUSIONS: The feline cornea is highly susceptible to in vitro binding and invasion by A. castellanii . Acanthamoeba binding to the feline cornea does not require a previous epithelial defect.

A genome-wide association study to investigate genetic loci associated with primary glaucoma in American Cocker Spaniels.

OBJECTIVE: To identify genetic associations with primary glaucoma (PG) in American Cocker Spaniels using a genome-wide association study (GWAS). ANIMALS: 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. PROCEDURES: 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. RESULTS: 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). CLINICAL RELEVANCE: 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.

Surgical correction of third eyelid cartilage eversion in an Anglo-Nubian goat: A case report.

This case of everted third eyelid cartilage in a goat demonstrates that everted cartilage occurs in animals other than domestic dogs and cats. Everted cartilage in the goat can be treated successfully with surgical excision of the abnormally bent cartilage.

Complex Feline Disease Mapping Using a Dense Genotyping Array.

The current feline genotyping array of 63 k single nucleotide polymorphisms has proven its utility for mapping within breeds, and its use has led to the identification of variants associated with Mendelian traits in purebred cats. However, compared to single gene disorders, association studies of complex diseases, especially with the inclusion of random bred cats with relatively low linkage disequilibrium, require a denser genotyping array and an increased sample size to provide statistically significant associations. Here, we undertook a multi-breed study of 1,122 cats, most of which were admitted and phenotyped for nine common complex feline diseases at the Cornell University Hospital for Animals. Using a proprietary 340 k single nucleotide polymorphism mapping array, we identified significant genome-wide associations with hyperthyroidism, diabetes mellitus, and eosinophilic keratoconjunctivitis. These results provide genomic locations for variant discovery and candidate gene screening for these important complex feline diseases, which are relevant not only to feline health, but also to the development of disease models for comparative studies.

Comparative Efficacy of Topical Ophthalmic Ganciclovir and Oral Famciclovir in Cats with Experimental Ocular Feline Herpesvirus-1 Epithelial Infection.

Purpose: To determine the comparative efficacy of ganciclovir ophthalmic gel and famciclovir oral tablets in cats with experimentally induced ocular feline herpesvirus-1 (FHV-1) epithelial infection. Methods: A randomized, placebo-controlled trial was performed using 16 nonvaccinated, specific pathogen-free cats with experimental FHV-1 infection induced by topical ocular inoculation. Cats received topical ganciclovir 0.15% ophthalmic gel (1 drop 3 times daily, n = 6 cats), oral famciclovir (90 mg/kg twice daily, n = 6), or topical artificial tear gel (1 drop 3 times daily, n = 4) for 14 days. Cats were monitored after inoculation for 30 days. Ophthalmic examinations were performed every 2 days and ocular disease scores calculated. In vivo confocal microscopy was performed, and corneal leukocyte infiltrates quantified. Ocular samples for FHV-1 quantitative polymerase chain reaction (qPCR) and virus isolation assays were collected every 3 days. Hemograms and serum biochemistry panels were performed at intervals. Results: Clinical ocular disease scores and corneal leukocyte infiltrates were significantly lower in the ganciclovir and famciclovir groups compared with placebo, but no significant differences were detected between the antiviral treatment groups. Ocular viral loads determined by qPCR were significantly lower in the ganciclovir group compared with the placebo group, but there were no significant differences between the other study groups. Hemograms and biochemistry panels were unremarkable. Conclusion: Topical application of ganciclovir gel 3 times daily was well-tolerated and displayed similar efficacy at reducing clinical ocular disease scores and corneal inflammation as twice daily oral famciclovir treatment in cats with experimental ocular FHV-1 infection.

Sports ball projectile ocular trauma in dogs.

OBJECTIVE: To describe the clinical features, management, and outcome of dogs presenting with sports ball projectile ocular injuries. ANIMALS STUDIED: Eighteen dogs. PROCEDURES: A retrospective study reviewing cases of ocular injury due to a sports ball projectile that presented to the Cornell University ophthalmology service between 2004 and 2021. Dog age, type of sports ball, initial ocular lesions, eye affected, clinical management, and visual outcome were recorded. RESULTS: Sports ball projectile ocular injuries were identified in 18 eyes of 18 dogs. The median age of the dogs was 1.0 years old, ranging from 0.3- to 9-years- old. Nine dogs were male, and 9 were female. Ocular injuries were caused by small, dense balls (e.g., golf balls, baseballs) in 11 dogs; small, light balls (e.g., tennis balls, toy balls) in 5 dogs; and large, soft balls (e.g., soccer ball, football) in 2 dogs. Closed-globe injuries (12 of 18 eyes) presented with traumatic uveitis (91%), hyphema (45%), and subconjunctival hemorrhage (18%). All 12 closed-globe injury cases were medically managed, eight dogs remained visual. Open-globe injuries (6 of 18 dogs) presented with three corneal lacerations and three scleral ruptures. Five open-globe injuries required enucleation, and one was medically managed and maintained vision. CONCLUSION: Sports ball projectile ocular injuries in dogs can result in substantial ocular morbidity and in loss of vision. Small, dense balls were associated with injuries that carried the most guarded prognosis and required more aggressive management. Small and large lighter projectiles were associated with less serious ocular injuries and visual outcomes.

Retrospective evaluation of phacoemulsification and aspiration in 182 eyes: Visual outcomes and CDE-predictive value.

OBJECTIVE: To determine the effect of cumulative dissipated energy (CDE) on complications and visual outcome following cataract surgery in dogs. ANIMALS STUDIED: Records of 182 canine eyes that had undergone cataract surgery. PROCEDURES: Retrospective medical record review was conducted on dogs that underwent unilateral or bilateral elective cataract surgery by a single surgeon. Preoperative variables such as age, cataract duration, and pre-existing conditions were recorded. Intraoperative variables such as intraocular lens (IOL) status, phacoemulsification time, average power, irrigation fluid volume, and CDE were recorded. Postoperative complications and visual status at last follow-up were compared to these variables. RESULTS: Eighty-six percent of dogs were visual in one or both eyes at last follow-up (LFU) examination. Median follow-up time was 186 days postoperatively. Eyes that developed glaucoma had a significantly greater mean CDE (77.73 ± 80.11) than eyes that did not develop glaucoma (49.21 ± 38.93). Eyes that remained visual at the LFU examination had a significantly lower mean CDE (48.31 ± 37.14) than eyes that were blind at LFU (82.05 ± 82.73). Significantly lower mean CDEs were found in diabetic eyes, younger eyes, early-operated eyes (<1 month duration), and eyes with preoperative lens-induced uveitis. CONCLUSIONS: Higher CDE may be associated with an increased risk of postoperative glaucoma and loss of vision in dogs. Cumulative dissipated energy may be a useful prognostic indicator for success of canine cataract surgery.

Feline ophthalmomyiasis externa caused by Cuterebra larvae: four cases (2005-2020).

CASE SERIES SUMMARY: Described are four cats diagnosed with ophthalmomyiasis externa caused by Cuterebra larvae. Medical records were retrospectively reviewed to identify cats with ophthalmomyiasis externa between 2005 and 2020 at Cornell University Hospital for Animals. Signalment, history, clinical and diagnostic findings, treatment and outcome were recorded. All cats were young (< 3 years of age), had outdoor access and were initially examined during the summer months. All cases had unilateral disease with the right eye affected. Two cases had nictitating membrane lesions and two had orbital disease. Concurrent superficial corneal ulceration was present in three cats. Two cats suffered from pyrexia, suspected secondary to inflammation from the larval infestation. Successful larval removal was performed in all cats, which resulted in improvement of discomfort and clinical signs. A corneal ulcer persisted in one cat, which was lost to follow-up prior to ulcer resolution. Parasite identification confirmed Cuterebra species infestation in all cases. RELEVANCE AND NOVEL INFORMATION: To the authors' knowledge, this is the first report of feline ophthalmomyiasis externa caused by Cuterebra species. Parasite removal was successful in restoring comfort and resolving clinical signs in all cats with adequate follow-up information.

Applications of in vivo confocal microscopy in the management of infectious keratitis in veterinary ophthalmology.

In vivo confocal microscopy (IVCM) is a relatively new ocular imaging technique that permits morphological and quantitative assessment of the living cornea on the cellular level. The applications for IVCM in clinical ophthalmology are numerous and diverse. There are several advantages inherent to IVCM over standard diagnostic techniques currently used to confirm a diagnosis of infectious keratitis in veterinary ophthalmology. With IVCM, images can be viewed in real-time providing immediate diagnostic information. Traumatic corneal sampling techniques are avoided, and the procedure can be repeated as frequently as is clinically indicated without risk of corneal tissue damage. Both superficial and deep corneal lesions can be evaluated by IVCM in an atraumatic fashion. Microorganism viability is not required for their detection and specialized diagnostic laboratory assay procedures are not necessary. Many larger infectious agents can be directly identified within corneal lesions by IVCM, including fungi and parasites such as Acanthamoeba spp. In other situations, such as bacterial infectious crystalline keratopathy, the biological systems associated with the microorganism can be detected within the cornea. The current resolution of IVCM is inadequate to directly visualize some corneal infectious agents, such as herpesviruses, but host responses and virus-infected epithelial cells can be identified. This review summarizes the current knowledge and applications of IVCM in the management of infectious keratitis in veterinary ophthalmology, including its use in animals with bacterial, fungal, parasitic, and viral keratitis.

In vivo confocal microscopic features of naturally acquired canine herpesvirus-1 and feline herpesvirus-1 dendritic and punctate ulcerative keratitis.

OBJECTIVE: To describe the in vivo confocal microscopy (IVCM) features of the corneal epithelium and stroma in dogs and cats with herpetic dendritic ulcerative keratitis. ANIMALS: 6 client-owned dogs and 10 client-owned cats with herpetic dendritic ulcerative keratitis (affected group) and 10 dogs and 10 cats from specific-pathogen-free laboratory colonies (nonaffected group). PROCEDURES: After complete ophthalmic examination, IVCM corneal examination was performed on the clinically diseased eyes of animals in the affected group and on both eyes of animals in the nonaffected group. Results by species were compared between groups. RESULTS: In the affected group, all 6 dogs had unilateral ocular lesions (total, 6 eyes examined), whereas 7 cats had unilateral lesions and 3 cats had bilateral lesions (total, 13 eyes examined). For the nonaffected group, 20 cat eyes and 20 dog eyes were examined. Corneal epithelial morphological abnormalities were identified in all examined eyes of animals in the affected group and in no examined eyes of the nonaffected group. Hyperreflective punctate opacities and inflammatory cells were present in all epithelial layers in examined eyes of affected animals but were absent in nonaffected animals. Similarly, Langerhans cells and anterior stromal dendritic cells were identified in corneas of eyes examined for animals in the affected group but not in any eye of animals in the nonaffected group. Stromal changes were less consistent in the affected group, but absent in the nonaffected group. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that herpetic dendritic ulcerative keratitis in dogs and cats is associated with microanatomic corneal abnormalities that can be detected by IVCM.

Intensive ocular sampling for the detection of subclinical canine herpesvirus-1 shedding in dogs with experimentally-induced latent infection.

Latent canine herpesvirus-1 (CaHV-1) infections are common in domestic dogs, but viral shedding patterns in dogs are poorly understood. Previous research failed to detect spontaneous subclinical ocular CaHV-1 shedding in dogs following ocular infection, a situation that is fundamentally distinct from many of the alphaherpesviruses closely related to CaHV-1. One possible explanation for this finding is that the sampling interval in the prior studies evaluating ocular shedding patterns was too infrequent to detect rapidly cleared, brief ocular viral shedding episodes. To evaluate for this potential viral shedding scenario, 10 laboratory beagles recovered from experimental primary ocular CaHV-1 infection and with latent CaHV-1infection were intensively monitored for viral reactivation and shedding for 28 days. Clinical ophthalmic examinations were performed daily. Ocular swab samples were collected for CaHV-1 polymerase chain reaction 3 times daily and CaHV-1 virus neutralizing antibody assays were evaluated at 2-week intervals. No abnormalities suggestive of recurrent CaHV-1 ocular disease were observed during clinical ophthalmic examination in the dogs during the study. Ocular CaHV-1 shedding was not detected by polymerase chain reaction and CaHV-1 virus neutralizing antibody titers remained stable in all dogs for the study duration. In the present study utilizing frequent multiple daily sample collections, no evidence of subclinical ocular CaHV-1 shedding was detected in mature dogs with experimentally-induced latent CaHV-1 infection.

Amniotic membrane grafting for traumatic complete spectaculectomy and keratomalacia in a Boelen's python (Simalia boeleni).

OBJECTIVE: To describe the surgical repair of traumatic complete spectaculectomy and keratomalacia in a snake. ANIMALS: A 10.5-year-old, female, Boelen's python (Simalia boeleni) was presented with iatrogenic, near-complete spectaculectomy associated with bacterial keratitis, keratomalacia, and hypopyon. PROCEDURES: Corneal samples for cytological evaluation and bacterial culture were collected. Following medical stabilization of the bacterial keratitis, a double-layered dry amniotic membrane graft was placed. The first amniotic membrane layer was placed over the cornea with the edges tucked under the peripheral remnants of the spectacle and secured in place with fibrin glue. The second amniotic membrane layer was placed over the entirety of the spectacle remnant and secured in place with a combination of fibrin glue and sutures. Topical and systemic antimicrobials, topical ophthalmic lubricants, and systemic non-steroidal anti-inflammatory therapy were administered postoperatively. RESULTS: Heterophilic keratitis was identified by cytology and Enterobacter cloacae, Pseudomonas aeruginosa, and Staphylococcus sciuri were cultured from the corneal samples. The amniotic membrane grafts remained in place for several weeks. At 4 months postoperatively, the spectacle was completely regenerated, the subspectacular space restored, and the cornea was transparent. Spectacular vascularization and fibrosis then slowly cleared over the following 6 months. CONCLUSIONS AND CLINICAL RELEVANCE: Amniotic membrane grafting with fibrin glue is a relatively simple and effective surgical method to reconstruct extensive defects in the reptilian spectacle and to assist in the management of bacterial keratitis associated with spectacle avulsion.

Phylogenomic Analysis of Global Isolates of Canid Alphaherpesvirus 1.

Canid alphaherpesvirus 1 (CHV-1) is a widespread pathogen of dogs with multiple associated clinical signs. There has been limited prior investigation into the genomics and phylogeny of this virus using whole viral genome analysis. Fifteen CHV-1 isolates were collected from animals with ocular disease based in the USA. Viral DNA was extracted for Illumina MiSeq full genome sequencing from each isolate. These data were combined with genomes of previously sequenced CHV-1 isolates obtained from hosts in the UK, Australia and Brazil. Genomic, recombinational and phylogenetic analysis were performed using multiple programs. Two isolates were separated into a clade apart from the remaining isolates and accounted for the majority of genomic distance (0.09%): one was obtained in 2019 from a USA-based host (ELAL-1) and the other in 2012 from a host in Brazil (BTU-1). ELAL-1 was found to contain variants previously reported in BTU-1 but also novel variants in the V57 gene region. Multiple non-synonymous variants were found in USA-based isolates in regions associated with antiviral resistance. Evidence of recombination was detected between ELAL-1 and BTU-1. Collectively, this represents evidence of trans-boundary transmission of a novel form of CHV-1, which highlights the importance of surveillance for this pathogen in domestic dog populations.