Impact of fungal species cultured on outcome in horses with fungal keratitis.

PURPOSE: To determine the significance of Aspergillus and Fusarium spp., as identified by culture, on clinical outcome in equine keratomycosis. METHODS: Retrospective analysis of 66 horses (66 eyes) evaluated at the NCSU-VH diagnosed with keratomycosis from which Aspergillus or Fusarium spp. were cultured. Horses were classified into those who improved with medical management alone or those who required surgical intervention to improve. Horses who underwent surgery were divided into globe-sparing procedures or enucleation. Effects of bacterial co-infection, previous topical steroid or antifungal use, and time of year on fungal genus and outcome were evaluated. RESULTS: Aspergillus spp. was cultured from 41 eyes (63%), while 24 eyes (37%) cultured Fusarium spp. One horse cultured both species and was not included in further evaluation. From the horses that cultured Aspergillus spp., 28 eyes (68%) required surgical intervention to control the infection: 21 (75%) of these eyes maintained globe integrity, while 7 eyes (25%) were enucleated. Of those horses with Fusarium spp., 14 eyes (58%) required surgical intervention: 11 (79%) of these eyes maintained globe integrity, while 3 eyes (21%) were enucleated. Genus of fungus cultured was not significantly associated with the need for surgical intervention nor was it significantly associated with the necessity of globe-sparing surgery versus enucleation. Additionally, bacterial co-infection, previous steroidal or antifungal use, and time of year did not affect outcome or type of fungal species cultured. CONCLUSION: Equine keratomycosis from Fusarium spp. compared to keratomycosis from Aspergillus spp. is not associated with a different clinical outcome.

Retrobulbar pigmented peripheral nerve sheath tumor in a dog.

A 1-year-old male castrated Pug was referred for unilateral exophthalmos unresponsive to oral antibiotic and anti-inflammatory therapy. Clinical findings included exophthalmos of the left eye with lateral strabismus, resistance to retropulsion, and an elevated nictitans. Hematologic and biochemical analyses were within normal limits. Findings following computed tomography (CT) of the head included an expansile retrobulbar soft tissue mass with bony lysis extending into the left nasal cavity and nasopharynx. Ultrasound-guided fine-needle aspirates and biopsy samples obtained via rhinoscopy were nondiagnostic. Palliative exenteration was elected; the patient was euthanized 13 weeks following exenteration due to development of neurologic signs and perceived poor quality of life. The histopathologic diagnosis was a malignant pigmented peripheral nerve sheath tumor.

Presumed primary ocular lymphangiosarcoma with metastasis in a miniature horse.

A 7-year-old, 153.0-kg American Miniature mare presented for evaluation of keratoconjunctivitis of the right eye (OD). A superior palpebral conjunctival mass and stromal keratitis were diagnosed. The incisional biopsy diagnosis was a presumptive corneal hemangiosarcoma. Transpalpebral enucleation was performed, and histopathologic evaluation confirmed angiosarcoma of the conjunctiva, cornea, and extraocular muscles. The horse developed progressive epistaxis and orbital swelling following surgery. A systemic workup was performed 3 months after enucleation, revealing regrowth within the orbit and marked cranial cervical lymphomegaly, suggestive of metastasis. Humane euthanasia was performed, and necropsy confirmed a locally invasive periorbital tumor with metastasis to the submandibular tissue, submandibular lymph node, and thoracic inlet. Histopathologic evaluation of necropsy specimens revealed polygonal to spindle neoplastic cells lining neoplastic vascular channels lacking erythrocytes. Immunohistochemically, the neoplastic cells labeled strongly positive for PROX-1, vimentin, CD-31, VEGF, weakly positive for factor VIII-related antigen, and negative for collagen IV. Based on the clinical, histological, and immunohistochemical features of this tumor, a primary ocular lymphangiosarcoma with metastasis was diagnosed.

Equine eosinophilic keratitis in horses: 28 cases (2003-2013).

This retrospective case series evaluates husbandry and environmental conditions in relation to eosinophilic keratitis in horses. While no associations were found between disease and husbandry practices or specific environmental factors such as humidity or temperature, an increased prevalence of presentation in summer months was identified in this population of horses.

Histopathological features of equine superficial, nonhealing, corneal ulcers.

OBJECTIVE: To evaluate corneal changes associated with chronic, nonhealing, superficial, corneal ulcers in horses via common histopathological stains. DESIGN: Retrospective study. ANIMALS: Twenty-four horses diagnosed with chronic, nonhealing, superficial, corneal ulceration. METHODS: The medical records of horses evaluated at North Carolina State University's Veterinary Teaching Hospital (NCSU-VTH) from 2005 to 2011, diagnosed with a chronic, nonhealing, superficial, corneal ulcer and treated with superficial keratectomy (SK) were reviewed. Inclusion criteria were superficial corneal ulceration, no cellular infiltration via slit-lamp biomicroscopy, no microorganisms evident on corneal cytology, and acquisition of samples for aerobic bacterial and common fungal cultures. Corneal tissue samples were evaluated histopathologically for the presence or absence of a nonadherent epithelial 'lip', epithelial dysmaturity, intraepithelial inflammatory cells, an acellular hyaline zone in the anterior stroma, and stromal inflammatory cells, fibrosis and vascularization. RESULTS: In the majority of analyzed samples, epithelial cells adjacent to the ulcerated site showed nonadherence to the basement membrane and dysmaturity. Intraepithelial inflammatory cell infiltration was uncommon. Histopathological features of an anterior stromal hyaline zone, intrastromal inflammation, fibrosis and vascularization were variably present. CONCLUSIONS: The most consistent histopathological characteristics of equine chronic, nonhealing, superficial, corneal ulcers include epithelial nonadherence, epithelial dysmaturity and mild to moderate stromal inflammation; however, one set of histopathological characteristics does not definitively define this syndrome in horses. Additionally, the anterior stromal acellular hyaline zone commonly cited in canine spontaneous chronic corneal epithelial defects (SCCED) is not a consistent finding in equine corneas.

Treatment of immune-mediated keratitis in horses with episcleral silicone matrix cyclosporine delivery devices.

PURPOSE: To describe the use of episcleral silicone matrix cyclosporine (ESMC) drug delivery devices in horses with immune-mediated keratitis (IMMK) with evaluation of tolerability and efficacy in long-term control of inflammation. METHODS: Retrospective study. ESMC implants (1.2 cm length, 30% wt/wt cyclosporine (CsA) in silicone; with approximately 2 µg/day steady-state release for at least 400 days) were used. RESULTS: Nineteen horses (20 eyes) received two or more ESMC implants for superficial stromal (n = 9), midstromal (n = 3), or endothelial (n = 5) IMMK. Three additional horses received two or more ESMC implants for pigmentary keratouveitis (PK). Nine eyes of eight horses with superficial and five eyes of five horses with endothelial IMMK were well controlled after placement of ESMC implants (mean follow-up 176.8 and 207.2 days, respectively). Horses with midstromal IMMK and PK were not controlled with ESMC implants alone, but instead required frequent use of other medications or surgery to control the disease. The mean duration of disease prior to ESMC implantation of horses with midstromal IMMK was 495 ± 203.9 days, compared with 121.6 ± 92.7 days with superficial IMMK. ESMC implants were well tolerated by all horses without documented loss of the device. CONCLUSIONS: Results from this preliminary retrospective study suggest that the ESMC implants were well tolerated and associated with treatment success with superficial and endothelial IMMK, especially if placed early in the disease process. Further study is needed to determine the duration of efficacy, number of implants required, and better therapies for chronic midstromal IMMK and pigmentary keratouveitis.

Evaluation of the effects of tricaine methanesulfonate on retinal structure and function in koi carp (Cyprinus carpio).

OBJECTIVE: To determine whether repeated exposure to clinically relevant concentrations of tricaine methanesulfonate (MS-222) would alter retinal function or induce histologically detectable retinal lesions in koi carp (Cyprinus carpio). DESIGN: Prospective, controlled, experimental study. ANIMALS: 18 healthy koi carp. PROCEDURES: 2 fish were euthanized at the start of the study, and eyes were submitted for histologic evaluation as untreated controls. Anesthesia was induced in the remaining fish with 200 mg of MS-222/L and maintained with concentrations of 125 to 150 mg/L for a total exposure time of 20 minutes daily on 1 to 13 consecutive days. On days 1, 7, and 13, electroretinography of both eyes was performed in all fish remaining in the study, and 2 fish were euthanized immediately after each procedure for histologic evaluation of the eyes. Median b-wave amplitudes were compared among study days for right eyes and for left eyes via 1-way repeated-measures ANOVA with a Bonferroni correction for multiple comparisons. RESULTS: Median b-wave amplitudes on days 1, 7, and 13 were 17.7, 20.9, and 17.6 µV, respectively, for right eyes and 15.1, 16.9, and 14.3 µV, respectively, for left eyes. No significant differences in b-wave amplitudes were detected among study days. No histopathologic abnormalities were identified in the retinas of any fish treated with MS-222 or in control fish. CONCLUSIONS AND CLINICAL RELEVANCE: Short-term exposure of koi carp to clinically relevant concentrations of MS-222 daily for up to 13 days was not associated with changes in retinal structure or function as measured in this study.

Phacoemulsification and +14 diopter intraocular lens placement in a Saddlebred foal.

A 2-month-old, 110-kg Saddlebred filly presented for evaluation of bilateral cataracts. A hypermature cataract in the left eye (OS) and an incipient nuclear cataract in the right eye (OD) were diagnosed. Electroretinography and ocular ultrasound revealed no contraindications for surgical removal of the cataractous lens OS. Phacoemulsification and implantation of a +14 diopter (D) intraocular lens (IOL) OS were performed at 4 months of age without complication, with the exception of a partial iridectomy performed on a small iris section that prolapsed through the corneal incision. Complete ophthalmic examinations, including ocular ultrasound and streak retinoscopy, were performed 1, 2, 6 weeks, 4 months, 1, and 2 years postoperatively. Diffuse corneal edema and a superficial corneal ulcer developed OS during the early postoperative period and resolved without complication. Dyscoria was identified owing to anterior synechia of the dorsomedial iris at the incision site. Two years after surgery, menace response, palpebral reflex, dazzle reflex, and pupillary light reflexes were present in both eyes (OU). The IOL remained centrally positioned within the capsule, with mild anterior tilting of the superior portion of the IOL and mild fibrosis of the lens capsule. The postoperative net refractive error was +0.31 D OS. Based on this report, a +14 D IOL may be the appropriate choice following lens extraction in a foal to achieve refraction near emmetropia at maturity. To our knowledge, this is the first report of phacoemulsification and IOL implantation in a foal with long-term follow-up.

Immunohistochemical and immunopathologic characterization of superficial stromal immune-mediated keratitis in horses.

OBJECTIVE: To describe the immunopathologic characteristics of superficial stromal immune-mediated keratitis (IMMK) immunopathologically by characterizing cellular infiltrate in affected corneas of horses. ANIMALS: 10 client-owned horses with IMMK. PROCEDURES: Immunohistochemical staining was performed on keratectomy samples with equine antibodies against the T-cell marker CD3 and B-cell marker CD79a (10 eyes) and the T-helper cytotoxic marker CD4 and T-cell cytotoxic marker CD8 (6 eyes). Percentage of positively stained cells was scored on a scale from 0 (no cells stained) to 4 (> 75% of cells stained). Equine IgG, IgM, and IgA antibodies were used to detect corneal immunoglobulin via direct immunofluorescence (10 eyes). Serum and aqueous humor (AH) samples from 3 horses with IMMK were used to detect circulating and intraocular IgG against corneal antigens via indirect immunofluorescence on unaffected equine cornea. RESULTS: Percentage scores (scale, 0 to 4) of cells expressing CD3 (median, 2.35 [range, 0.2 to 3.7]; mean ± SD, 2.36 ± 1.08) were significantly greater than scores of cells expressing CD79a (median, 0.55 [range, 0 to 1.5]; mean, 0.69 ± 0.72). All samples stained positively for CD4- and CD8-expressing cells, with no significant difference in scoring. All samples stained positively for IgG, IgM, and IgA. No serum or AH samples collected from horses with IMMK reacted with unaffected equine cornea. CONCLUSIONS AND CLINICAL RELEVANCE: Pathogenesis of superficial stromal IMMK included cell-mediated inflammation governed by both cytotoxic and helper T cells. Local immunoglobulins were present in affected corneas; however, corneal-binding immunoglobulins were not detected in the serum or AH from horses with IMMK.

A retrospective comparison of surgical removal and subsequent CO2 laser ablation versus topical administration of mitomycin C as therapy for equine corneolimbal squamous cell carcinoma.

OBJECTIVE: To compare the complications and nonrecurrence rate following topical mitomycin C (MMC) therapy vs. CO(2) laser ablation for treating equine corneolimbal squamous cell carcinoma (SCC). STUDY DESIGN: Retrospective study. SAMPLE POPULATION: Twenty-five horses with corneolimbal SCC. PROCEDURES: Medical records of horses undergoing surgical tumor resection followed by either topical MMC therapy (0.04%) or CO(2) laser ablation between the years of 2004 and 2010 were reviewed. Recurrence and complications were compared between groups and within MMC subgroups defined by the time at which treatment was initiated relative to surgery. RESULTS: Therapy with topical MMC resulted in a nonrecurrence rate comparable to that achieved with CO(2) laser ablation (82.4% vs. 85.7%, respectively). Initiation of MMC following epithelialization of the surgical site a mean of 15 days postoperatively did not result in increased recurrence rates relative to treatment in the immediate postoperative period. Vision- or globe-threatening complications tended to occur with greater frequency in horses receiving topical MMC in the immediate postoperative period (5 of 6 major complications) relative to following epithelialization of the surgical site (1 of 6 major complications). CONCLUSIONS: Horses receiving adjunctive topical MMC therapy were no more likely to experience tumor recurrence than were horses undergoing CO(2) laser ablation in the horses in this study. Initiation of two to three rounds of MMC following epithelialization of the surgical site results in fewer major complications and achieves comparable disease resolution relative to treatment in the immediate postoperative period.

Diagnosis of intraocular lymphosarcoma in a dog by use of a polymerase chain reaction assay for antigen receptor rearrangement.

CASE DESCRIPTION: A 12-year-old castrated male mixed-breed dog was evaluated because of blepharospasm and blindness affecting both eyes. CLINICAL FINDINGS: During examination and diagnostic testing of the dog, fine-needle aspirates of splenic nodules were examined microscopically and stage Vb multicentric large-cell lymphosarcoma was identified. Aqueocentesis was performed, and sample analysis revealed intraocular lymphosarcoma; B-cell neoplasia was confirmed by use of a PCR assay for antigen receptor rearrangement (PARR) performed on samples of aqueous humor. Secondary uveitis and glaucoma were detected bilaterally in addition to chronic superficial corneal ulcerations in the left eye. TREATMENT AND OUTCOME: Treatment for abdominal and intraocular lymphosarcoma involving administration of vincristine, l-asparaginase, cyclophosphamide, doxorubicin, and prednisone was initiated. Secondary uveitis and glaucoma were controlled with topical treatment; however, the corneal ulceration did not resolve. Seven weeks following diagnosis, the dog died as a result of complications related to systemic neoplasia and chemotherapy. CLINICAL RELEVANCE: In the dog of this report, intraocular lymphosarcoma was diagnosed via PARR performed on samples of aqueous humor. Moreover, the immunophenotype of the neoplastic cells was determined by use of that diagnostic technique. Because secondary uveitis is a common finding in dogs and cats with systemic lymphosarcoma, intraocular lymphosarcoma should be considered as a differential diagnosis; furthermore, investigation (eg, PARR performed on aqueous humor samples) to identify the presence of intraocular lymphosarcoma is warranted, thereby allowing targeted interventions to be considered in management of those patients.

Anomalous nasolacrimal openings in a 2-year-old Morgan filly.

This case report describes the clinical, diagnostic, computed tomography findings, and surgical treatment of a 2-year-old Morgan filly with bilateral, proximal, and distal anomalous nasolacrimal duct openings.

Aqueous humor and plasma concentrations of ciprofloxacin and moxifloxacin following topical ocular administration in ophthalmologically normal horses.

OBJECTIVE: To determine the degree of ocular penetration and systemic absorption of commercially available topical ophthalmic solutions of 0.3% ciprofloxacin and 0.5% moxifloxacin following repeated topical ocular administration in ophthalmologically normal horses. ANIMALS: 7 healthy adult horses with clinically normal eyes as evaluated prior to each treatment. PROCEDURES: 6 horses were used for assessment of each antimicrobial, and 1 eye of each horse was treated with topically administered 0.3% ciprofloxacin or 0.5% moxifloxacin (n = 6 eyes/drug) every 4 hours for 7 doses. Anterior chamber paracentesis was performed 1 hour after the final dose was administered, and blood samples were collected at 24 (immediately after the final dose), 24.25, 24.5, and 25 hours (time of aqueous humor [AH] collection). Plasma and AH concentrations of ciprofloxacin or moxifloxacin were determined by use of high-performance liquid chromatography. RESULTS: Mean +/- SD AH concentrations of ciprofloxacin and moxifloxacin were 0.009 +/- 0.008 microg/mL and 0.071 +/- 0.029 microg/mL, respectively. The AH moxifloxacin concentrations were significantly greater than those of ciprofloxacin. Mean +/- SD plasma concentrations of ciprofloxacin were less than the lower limit of quantification. Moxifloxacin was detected in the plasma of all horses at all sample collection times, with a peak value of 0.015 microg/mL at 24 and 24.25 hours, decreasing to < 0.004 microg/mL at 25 hours. CONCLUSIONS AND CLINICAL RELEVANCE: Moxifloxacin was better able to penetrate healthy equine corneas and reach measurable AH concentrations than was ciprofloxacin, suggesting moxifloxacin might be of greater value in the treatment of deep corneal or intraocular bacterial infections caused by susceptible organisms. Topical administration of moxifloxacin also resulted in detectable plasma concentrations.

Effect of three treatment protocols on acute ocular hypertension after phacoemulsification and aspiration of cataracts in dogs.

OBJECTIVE: To compare the effect of topical latanoprost, intracameral carbachol, or no adjunctive medical therapy on the development of acute postoperative hypertension (POH) and inflammation after routine phacoemulsification and aspiration (PA) of cataracts in dogs. DESIGN: Retrospective study. PROCEDURES: Dogs received either one drop of topical 0.005% latanoprost (21 dogs, 39 eyes), an intracameral injection of 0.3 mL of 0.01% carbachol (15 dogs, 30 eyes), or no adjunctive therapy (46 dogs, 90 eyes) immediately following PA of cataract(s). Intraocular pressure (IOP) was measured in all dogs 2 and 4 h after surgery. IOP was measured and aqueous flare assessed at 8 am the day after surgery. RESULTS: Carbachol-treated dogs had significantly higher mean IOP (33.2 +/- SD 20.8 mmHg) 2 h after surgery than dogs receiving no adjunctive therapy (22.0 +/- SD 14.1 mmHg) (P = 0.049). There were no significant differences in IOP among groups at any other time point. There were no significant differences in number of POH episodes between dogs treated with carbachol (47%), latanoprost (29%), or dogs that received no adjunctive therapy (33%). There were no significant differences in mean aqueous flare grade between eyes treated with latanoprost (1.7 +/- SD 0.4) or carbachol (1.4 +/- SD 0.6), and eyes that received no adjunctive therapy (1.7 +/- SD 0.4). CONCLUSIONS: Topical 0.005% latanoprost or intracameral injection of 0.3 mL of 0.01% carbachol after PA in dogs did not reduce POH or increase intraocular inflammation compared to dogs not receiving adjunctive therapy after PA of cataracts.

Surgical correction of severe strabismus and enophthalmos secondary to zygomatic arch fracture in a dog.

A grossly displaced segmental zygomatic arch fracture with marked ventro-lateral deviation of the left globe was diagnosed in a 3-month-old male German Shepherd dog following a bite injury. The fracture was approached via a modified lateral orbitotomy and a fragment of the lacrimal bone removed. The rostral portion of the fracture was stabilized with a 5-hole 2.0 dynamic compression plate bone plate. The surgical correction achieved sufficient skeletal fixation for proper anatomical reduction of the globe and excellent cosmetic and functional outcomes.

Infrared digital imaging of the equine anterior segment.

Ocular photographs are an increasingly important method of documenting lesions for inclusion in medical records, teaching purposes, and research. Availability of affordable high-quality digital imaging equipment has allowed for enhanced capture of desired images because of immediate on-camera viewing and editing. Conversion of the standard digital camera sensor to one that is sensitive to infrared light (i.e. > 760 nm < 1 mm wavelength) can be done inexpensively. In the equine eye, advantages of infrared digital photography include increased contrast of anterior segment images, identification and monitoring of pigmentary changes, and increased visualization of the anterior segment through a cloudy or edematous cornea.

Epibulbar melanoma in a foal.

A case of epibulbar melanoma in a 6-month-old, gelded, chestnut Hanoverian foal is reported. The location and clinical appearance upon initial presentation led to the tentative diagnosis of staphyloma or a congenital mass of unknown origin. An attempt was made to surgically excise the mass under general anesthesia, but due to its infiltrative nature and intraoperative appearance, most, but not all was removed without compromising the integrity of the globe. Histopathological evaluation revealed a multinodular to packeted, poorly demarcated, unencapsulated, infiltrative exophytic melanocytic neoplasm composed of bundles and nests of plump spindloid to polygonal heavily pigmented epithelioid neoplastic cells interspersed with pigment-laden macrophages within a fine fibrovascular stroma. Upon examination after enucleation, neoplastic cells were found to infiltrate into the lateral cornea, sclera and the choroid. This is a unique case of an epibulbar melanoma with choroidal invasion in a foal. Based on the sudden onset and rapid growth as well as the histological evidence of invasion, well-differentiated features, heavy pigmentation, and no apparent mitoses, this neoplasm was considered to be a low-grade malignant melanoma. At 14 months after excision there is no evidence of recurrence.

Evaluation of concentration of voriconazole in aqueous humor after topical and oral administration in horses.

OBJECTIVE: To determine penetration of topically and orally administered voriconazole into ocular tissues and evaluate concentrations of the drug in blood and signs of toxicosis after topical application in horses. ANIMALS: 11 healthy adult horses. PROCEDURE: Each eye in 6 horses was treated with a single concentration (0.5%, 1.0%, or 3.0%) of a topically administered voriconazole solution every 4 hours for 7 doses. Anterior chamber paracentesis was performed and plasma samples were collected after application of the final dose. Voriconazole concentrations in aqueous humor (AH) and plasma were measured via high-performance liquid chromatography. Five horses received a single orally administered dose of voriconazole (4 mg/kg); anterior chamber paracentesis was performed, and voriconazole concentrations in AH were measured. RESULTS: Mean +/- SD voriconazole concentrations in AH after topical administration of 0.5%, 1.0%, and 3.0% solutions (n = 4 eyes for each concentration) were 1.43 +/- 0.37 microg/mL, 2.35 +/- 0.78 microg/mL, and 2.40 +/- 0.29 microg/mL, respectively. The 1.0% and 3.0% solutions resulted in significantly higher AH concentrations than the 0.5% solution, and only the 3.0% solution induced signs of ocular toxicosis. Voriconazole was detected in the plasma for 1 hour after the final topically administered dose of all solutions. Mean +/- SD voriconazole concentration in AH after a single orally administered dose was 0.86 +/- 0.22 microg/mL. CONCLUSIONS AND CLINICAL RELEVANCE: Results indicated that voriconazole effectively penetrated the cornea in clinically normal eyes and reached detectable concentrations in the AH after topical administration. The drug also penetrated noninflamed equine eyes after oral administration. Low plasma concentrations of voriconazole were detected after topical administration.