Equine keratomycosis in Japan

Objective To describe the incidence, clinical progress, visual outcome, and laboratory findings of equine keratomycosis in Japan. Procedure Retrospective study of the medical records of horses clinically and mycologically diagnosed with keratomycosis at the Equine Hospitals of the Japan Racing Association from 2005 to 2011. Results The diagnosis of keratomycosis was confirmed in eight horses (40.0% of the 20 horses with infectious keratitis from which fungi and/or bacteria were isolated). Fungi recovered from corneal swabs were identified as Aspergillus flavus (4), Aspergillus niger (1), Fusarium solani (1), and Mortierella wolfii (2). All horses were treated medically with topical antifungals, and one horse was also treated surgically. The median of treatment period was 40 days. Two horses were rendered blind in the affected eye and the others retained vision. Conclusions Equine keratomycosis comprises a considerable portion of infectious keratitis in Japan, and the causative fungi that we isolated had been isolated previously from horses with keratomycosis in other regions with the exception of M. wolfii. Culture and cytological examination of corneal lesions should be immediately performed on eyes with signs of keratitis, particularly on those not improving with antibacterial medication, as early initiation of aggressive antifungal treatment tended to result in better outcome and shorter treatment period.     

Rose bengal positive epithelial microerosions as a manifestation of equine keratomycosis

Purpose To describe the clinical appearance of corneal epithelial cell microerosions associated with keratomycosis in the horse. METHODS: Retrospective clinical study. RESULTS: Multifocal, punctate, superficial corneal opacities with positive rose bengal retention were noted in six horses with presumed 'viral keratitis'. Faint fluorescein staining was also present in three cases. Equine herpesvirus tissue culture inoculation was negative for a cytopathic effect in three cases. Aspergillus (n = 3), Curvularia (n = 1), and an unidentified fungus (n = 1) were cultured in five horses, and hyphae found on corneal cytology from the sixth. Mixed bacterial infections were present in three eyes. The eyes of two horses with Aspergillus progressed to deep melting corneal ulcers that required surgical therapy. The microerosions remained superficial, but persistent in the other four eyes. Natamycin was utilized topically in all six horses. Transmission electron microscopy from case 6 revealed mucin layer disruption, an intact corneal epithelial cell layer, and fungal attachment to degenerating epithelial cells. The visual outcome was positive in all six horses, although healing was prolonged (48.5 +/- 14.5 days on average in the horses with no surgery; 62 days on average in the two horses that required surgery). CONCLUSIONS: Complete removal or full-thickness penetration of the corneal epithelial cell barrier may not be necessary to allow fungal adherence and initiation of keratomycosis in the horse. Prior to colonization and invasion of the horse cornea, fungi may induce changes in the mucin layer of the tear film that result in or are associated with rose bengal positive microerosions of the superficial corneal epithelium. Horses with painful eyes, and eyes with superficial, multifocal corneal opacities should have their corneas stained with both fluorescein and rose bengal as fungal microerosions may stain weakly, or not at all, with fluorescein, and may thus be mistaken for presumed 'viral keratitis' of the horse.     

Clinical findings and outcomes of ulcerative keratomycosis in 30 horses in the mid‐Atlantic United States (2006–2007)

The purpose of this study was to determine the clinical course and outcome associated with keratomycosis in horses in the mid‐Atlantic USA. Records of horses diagnosed with keratomycosis at New Bolton Center from November 2006 to November 2007 with positive fungal culture were retrospectively studied. Neither horses with ulcerative keratitis and a negative fungal culture nor those with stromal abscesses were included. Subject details, history, clinical findings, therapy and outcome were recorded. Thirty horses fitted both inclusion criteria (diagnosis of keratomycosis and positive corneal fungal culture). Fourteen of 30 cases occurred during summer. Aspergillus was the most commonly cultured fungal genus (17/30, or 57%) followed by Alternaria (4/30). Seventeen horses had positive bacterial and fungal cultures. Fifteen of 30 horses were treated surgically by a keratectomy and amnion (8) or conjunctival (7) graft. Itraconazole was the most common topical anti‐fungal therapy and was utilised in 25/30 horses. Globe survival was 97% (29/30). All surviving globes had a positive menace response and were visual at the last examination. It was concluded that in the mid‐Atlantic USA, fungal keratitis is common, has the highest incidence in summer, and is usually associated with a positive outcome. Aspergillus may be a relatively more common corneal pathogen in this region than elsewhere in the USA. Surgical cases were more likely to have fungal hyphae identified on cytology and tended to be hospitalised longer than medical cases. There was no apparent association between surgical disease and all other patient, organism and treatment variables.     

Hormographiella aspergillata keratomycosis in a dog

A 4-year-old, female, Border Collie was presented to the University of Bern Veterinary Teaching Hospital, because of a corneal lesion of 10 days duration. The axial cornea presented a whitish fluorescein-positive plaque with irregular margins. A diagnosis of keratomycosis was made based on cytology. Medical therapy with local broad-spectrum antibiotic and fluconazole was instituted. After 1 week of treatment, the improvement was deemed unsatisfactory. Therefore, a lamellar keratectomy and conjunctival pedicle flap were performed. After surgery, the cornea healed uneventfully. Histology confirmed the diagnosis of keratomycosis. The fungus could not be grown in culture and a precise etiological diagnosis could only be obtained with genetic identification of the fungus. A PCR technique was used to amplify the fungal genome from the cornea. Hormographiella aspergillata , the asexual reproductive form of the basidiomycete Coprinopsis cinerea , was identified. As advised in human medicine, we encourage the use of this molecular technique to obtain an early species diagnosis, allowing targeted medical therapy.     

Scedosporium apiospermum keratomycosis in a dog

A 6‐year‐old male castrated Norfolk Terrier dog was examined following a 21‐day history of an increasingly painful eye. Examination revealed marked blepharospasm and purulent ocular discharge associated with an ulcerative keratitis. There was panstromal corneal opacity with raised gray to white lesions. Corneal cytology demonstrated branching septate fungal hyphae identified by polymerase chain reaction as Scedosporium apiospermum. Treatment with topical 1% voriconazole solution was successful in resolving the keratomycosis.     

Keratomycosis in five dogs

Five cases of canine keratomycosis were diagnosed and treated at a private Veterinary Ophthalmology Practice in Melbourne, Australia. Clinical presentations varied between dogs. Predisposing factors were identified in 4 of 5 cases. Diagnostic modalities utilized were corneal cytology and fungal culture. Corneal cytology confirmed the presence of fungal organisms in all five cases. Aspergillus, Scedosporium, and Candida were cultured from three cases, respectively. Specific antifungal treatment included 1% voriconazole solution or 1% itraconazole ointment. Keratectomy and conjunctival grafting surgery was performed in two patients. Resolution of infection and preservation of vision were achieved in 4 of 5 patients.     

Bacteroides sp. as a cause of anaerobic keratitis in a pony

This Case Report describes anaerobic infection of the conjunctiva and cornea in a pony. A 13‐year‐old pony was admitted for evaluation following suspected ocular trauma. Bacterial conjunctivitis and keratitis were diagnosed based on clinical appearance of the eye and cytological evaluation of a corneal scraping. The pony responded poorly to topical therapy, and enucleation was performed. Culture of the corneal scraping yielded Corynebacterium sp. and Bacteroides sp. Anaerobic keratitis and conjunctivitis is uncommonly reported in horses, but should be suspected when there is a history of ocular trauma or skin disease, or when a malodorous ocular discharge is identified.     

Mycotic pneumonia, placentitis and neonatal encephalitis in dairy cattle caused by Mortierella wolfii

SUMMARY Within 22 days after 30 pregnant cows inadvertently received silage ad libitum, one had a mycotic abortion and 2 gave birth to calves with mycotic encephalitis. The latter 2 cows both developed severe mycotic pneumonia within 3 days of parturition. Variable diameter, non-septate, irregularly branching fungal hyphae were found in all lesions. Mortierella wolfii was cultured from the cow's lung, both calf brains and the silage, which was the probable source of infection.     

Prevalence of equine ulcerative keratomycosis in Colorado and association of environmental factors: A retrospective and descriptive study (2002–2017)

Equine ulcerative keratomycosis is relatively commonly presented to teaching hospitals in North America, with a prevalence from 24 to 86%. Horses in Colorado may have lower risk due to the dry mountain climate, but data are lacking. This study aimed to determine the prevalence of ulcerative keratomycosis amongst horses with ulcerative keratitis presented to Colorado State University Veterinary Teaching Hospital (CSU-VTH) ophthalmology service and to evaluate environmental factors (season, temperature, humidity, wind speed and elevation) associated with ulcerative keratomycosis in Colorado. A database search identified horses with ulcerative keratitis presented to the ophthalmology service at CSU-VTH from January 2002 to August 2017. Sixty-one horses met the inclusion criteria of a corneal cytology and/or culture or histopathology at the time of diagnosis; cases lacking that were excluded. Environmental factors at the boarding sites, including season, temperature, humidity, wind speed and elevation and clinical outcomes for fungal cases, were recorded. Prevalence of fungal infection amongst equine ulcerative keratitis was 16.4% (10/61), suggesting that CSU-VTH has considerably fewer ulcerative keratomycosis cases than other veterinary teaching hospitals in North America. Spring (50%, 5/10) and fall (40%, 4/10) had the highest prevalence of fungal ulcerative keratitis in Colorado. Only one case was reported in summer (10%, 1/10); no horses were positive (0%, 0/10) in winter. Only wind speed seemed to influence the development of ulcerative keratomycosis with higher wind speeds associated with greater rates of fungal involvement (P = 0.047). Other environmental factors did not show a detectable association (all P-values >0.05). Outcomes were variable. It was concluded that horses from the area of CSU-VTH appear to be at lower risk for ulcerative keratomycosis than from the areas around other North American veterinary teaching hospitals that have reported data. Most horses with keratomycosis in this area present in the spring and fall.     

Curvularia keratomycosis in a dog

A 10‐year‐old, spayed female Bichon Frise was referred to the Veterinary Medical Center of the University of Florida with a 6‐week history of blepharospasm and a nonhealing ulcer of the left eye. Ophthalmic examination revealed a 3–4 mm diameter corneal ulcer with faint edema at the lesion edge, and a raised grayish area on the paraxial cornea near the 2 o’clock position. Cytological testing revealed fungal hyphae and extracellular cocci. Culture of the lesion found heavy growth of Enterococcus faecalis and Curvularia spp. Treatment with a combination of topical antibiotics (polymyxin B, sulfate/trimetoprim, and 10% sulfacetamide sodium), 1% miconazole, autologous serum, and 5% hypertonic saline was instituted. After 8 days of medical therapy, an improvement of clinical signs was noted, and 15 days after initiation of treatment, the ulcer was healed with minimal corneal scarring.     

In vitro susceptibility patterns of fungi associated with keratomycosis in horses of the northeastern United States: 68 cases (1987-2006)

OBJECTIVE: To determine in vitro susceptibility patterns of fungi associated with keratomycosis in horses in the northeastern United States and compare those patterns with results of studies from other geographic regions. DESIGN: Retrospective case series. ANIMALS: 68 horses with keratomycosis. PROCEDURES: Medical records of horses with a clinical diagnosis of keratomycosis, positive results of corneal fungal cultures, and susceptibility data were reviewed from the years 1987 to 2006. Fungal identification and in vitro antifungal susceptibility test results were recorded. The percentage of susceptible isolates was compared among antifungals for all isolates together and for the most common genera individually. RESULTS: 74 fungal isolates from 68 horses that met inclusion criteria were identified. Aspergillus, Candida, and Fusarium spp were the most frequent isolates. Grouped isolates had the highest percentage of susceptibility to nystatin (87.7%), natamycin (87.5%), and clotrimazole (80.6%). Grouped isolates had the lowest percentage of susceptibility to fluconazole (15.8%) and miconazole (27.5%). Aspergillus spp (> or = 81.0%) were most susceptible to nystatin, clotrimazole, itraconazole, and natamycin. Candida spp (100%) were most susceptible to ketaconazole, natamycin, and nystatin. Fusarium spp (100%) were only consistently susceptible to natamycin. CONCLUSIONS AND CLINICAL RELEVANCE: On the basis of in vitro susceptibility testing, nystatin, natamycin, or clotrimazole is recommended for initial topical treatment of keratomycosis in horses from the northeastern United States. Contrary to results of studies of ocular fungal isolates of horses from other regions, Candida spp were identified more frequently and miconazole had lower in vitro efficacy in the present study.     

Listeria keratitis in a horse

Listeria monocytogenes is ubiquitous in the environment but is rarely reported as a cause of keratitis in animals. In this case, a mare was presented with epiphora and evidence of pain in the right eye. Listeria monocytogenes was isolated from a corneal lesion, and bacteria were also seen in the cytologic evaluation. This is the first reported case of ulcerative keratitis associated with L. monocytogenes in a horse.     

Equine keratomycoses in California from 1987 to 2010 (47 cases)

Reasons for performing study: Equine keratomycosis in the western USA has received little study, probably owing to its low prevalence. Objectives: To determine clinical features, predominant fungal isolates, treatment modalities and outcomes of horses with keratomycosis in California and compare these with results from different geographic regions. Methods: Records of horses presented to the University of California‐Davis Veterinary Medical Teaching Hospital (UCD‐VMTH) with confirmed keratomycosis between 1987 and 2010 were reviewed for this retrospective study. Information retrieved from the record included background, ophthalmic examination findings, treatment prior to and following presentation, visual outcome, and ocular survival. Results: A total of 48 eyes in 47 horses met the inclusion criteria and comprised 2% of cases presented to the UCD‐VMTH ophthalmology service. Prior to presentation, 20 horses (43%) received at least one topically administered anti‐inflammatory medication. Keratomycosis was confirmed by fungal culture in 38 horses (81%), by histopathology in 2 horses (4%) and by cytology in 7 horses (15%). Forty‐four isolates were identified in the 38 horses cultured; Aspergillus was the most common isolate (64%) and a novel isolate, Papulospora, was identified in 2 horses. Treatment consisted of medication only (73%), medical and surgical treatment (25%), or immediate enucleation (2%). Globe retention was 77% and vision retention was 53%. Corneal perforation was significantly associated with loss of vision (P<0.001). Conclusions: Keratomycosis is relatively uncommon in horses presented for ophthalmic conditions at UCD‐VMTH. Corneal perforation was a negative prognostic indicator for vision in this population of northern Californian horses.     

CASE REPORT: Keratomycosis in a dog treated with topical 1% voriconazole solution

A 2‐year‐old Jack Russell Terrier was presented for treatment of a worsening corneal ulcer and keratomalacia following removal of a vegetative foreign body. The keratomalacia responded to topical gentamicin therapy; however, the eye became suddenly painful and at examination two areas of increased opacity had developed. Fungal keratitis was demonstrated by corneal scrape showing branching, septate fungal hyphae. Treatment with 1% voriconazole was effective in resolving the keratomycosis.     

Clinical findings and progression of 10 cases of equine ulcerative keratomycosis (2004–2007)

Ulcerative keratomycosis is a serious sight‐threatening disease of horses and the veterinary literature is replete with cases of poor visual outcome following this condition. During a 3 year period, 10 horses were treated for confirmed keratomycosis at the Veterinary Teaching Hospital (VTH) of the University of Cordoba (Spain). Ulcerative keratomycosis accounted for an average of 8.62% of the total equine ophthalmic admissions during this time and an average of 33.3% of horses were diagnosed with infectious keratitis. Fungi were diagnosed using cytology (n = 4) and/or culture (n = 8) and histopathology (n = 1). Aspergillus sp. was the most commonly isolated fungus. Medical therapy alone or combined medical and surgical treatment was utilised for therapy depending on the clinical condition. Miconazole 1% was the most common topical antifungal therapy employed. Median duration of treatment was 73.12 days. Records were evaluated to determine visual outcome and globe survival.     

In vivo confocal microscopy of equine fungal keratitis

Objective To describe in vivo corneal confocal microscopy of horses with fungal keratitis and correlate findings with clinical, histopathological, and microbiological evaluations of clinical cases and an ex vivo experimental equine fungal keratitis model. Animals studied A total of 12 horses with naturally‐acquired fungal keratitis and ex vivo equine corneas experimentally infected with clinical fungal isolates. Procedures Horses with naturally‐acquired fungal keratitis were examined with a modified Heidelberg Retina Tomograph II and Rostock Cornea Module. Confocal microscopy images of clinical isolates of Aspergillus fumigatus, Fusarium solani, and Candida albicans were obtained by examination of in vitro cultures and experimentally infected ex vivo equine corneas. Results Non‐specific in vivo corneal confocal microscopic findings in horses with fungal keratitis included leukocyte infiltrates, activated keratocytes, anterior stromal dendritic cell infiltrates, and vascularization. Linear, branching, hyper‐reflective structures that were 2–6 μm in width and 200 to >400 μm in length were detected in all horses with filamentous fungal keratitis. Round to oval hyper‐reflective structures that were 2–8 μm in diameter were detected in a horse with yeast fungal keratitis. The in vivo confocal microscopic appearance of the organisms was consistent with fungal morphologies observed during examination of in vitro cultures and infected ex vivo equine corneas. Conclusions In vivo corneal confocal microscopy is a rapid and non‐invasive method of diagnosing fungal keratitis in the horse. This imaging technique is useful for both ulcerative and non‐ulcerative fungal keratitis, and is particularly advantageous for confirming the presence of fungi in deep corneal stromal lesions.     

Outcome of superficial keratectomy without conjunctival graft as a surgical technique for immune-mediated keratitis in horses: Four cases

This case report describes four horses with unilateral superficial or mid-stromal immune-mediated keratitis (IMMK) treated with a superficial keratectomy (SK) without a conjunctival graft. In two horses, the surgery was performed under general anaesthesia, and in two horses standing with sedation and local blocks. Results of this report show that SK is a viable treatment option in horses with chronic superficial and/or mid-stromal IMMK that can even be performed in the standing, sedated horse. When sufficient corneal tissue is removed, no recurrence is to be expected in the long-term follow-up (up to 31 months). In two horses, healing occurred without complications. Two horses developed a secondary bacterial infection post-operatively (Enterococcus faecalis and Staphylococcus aureus). In one case, this resulted in a pre-perforating melting corneal ulcer necessitating conjunctival pedicle graft surgery 13 days post keratectomy. In three horses, there was no recurrence of the IMMK with a long-term follow-up of 6–31 months. One case showed recurrence of IMMK in the cornea region surrounding the keratectomy 9 months after surgery.     

Ulcerative fungal keratitis in a Brown Swiss cow

An 11‐year‐old Brown Swiss cow was referred to the Farm Animal Department of the Veterinary Teaching Hospital in Zurich, Switzerland, because of lateral recumbency due to puerperal hemolytic anemia. The animal had developed enophthalmos due to dehydration at the time of presentation. Two days after hospitalization, the cow showed blepharospasm and epiphora of the right eye. Ophthalmic examination of the right eye revealed a fluorescein‐positive, paraxial, superficial corneal ulcer with focal edema, and mild superficial neovascularization. White corneal stromal infiltrates were seen at the edges of the ulcer bed. After initial topical treatment with an antibiotic ointment (Neomycin 3.5 mg/g, Bacitracin 250 IU/g) three times a day, an increase in corneal infiltrates was noted on re‐examination 2 days later. Several fluorescein‐negative, punctate, stromal, white opacities were seen dorsal to the ulcer. Cytology demonstrated the presence of fungal hyphae. Topical treatment with 2% miconazole ointment and 0.36% K‐EDTA eye drops six times daily and four times daily, respectively, from the second day and continued antibiotics three times daily resolved the clinical symptoms within 6 days. Fungal culture identified the fungal organism as Eurotium amstelodami.     

Antifungals and their use in veterinary ophthalmology.

Many variables affect the outcome of keratomycosis and systemic fungal infections in animals. These include pathogenicity of the fungal organism(toxins, trophisms, and evasion of host response); previous treatment with topical or systemic corticosteroids, which can have a dramatic negative impact on host defense mechanisms: concurrent systemic illness or immunocompromise: severity/extent of infection; and degree of pain (ie,increased reflex tearing dilutes topical medication) [14]. Experimental work suggests that antibiotics may occasionally exacerbate fungal infections [142],and some researchers advocate that concurrent antibiotic therapy is contraindicated in horses with yeast infections and septate fungal infections unless bacterial infection is also suspected [14]. Nevertheless, given that normal conjunctival flora often include bacteria and fungi and because care of keratomycoses often includes mixed bacterial and fungal infections, the possible dynamics (natural influences and local competition) between ocular surface microorganisms merit further investigation. There are many unanswered questions regarding the accuracy of in vitro susceptibilities and corneal concentration capabilities for antifungal topical medications [14].Inherent host resistance or other immune interactions between the patient and fungus are perhaps the most important determinants of the outcome but are currently difficult to measure or assess except by subjective clinical observation [14].