Progressive ulcerative keratitis in dogs in the United Kingdom: Microbial isolates, antimicrobial sensitivity, and resistance patterns

OBJECTIVES

The objective of the study was to identify bacterial pathogens and their antimicrobial sensitivity profile associated with cases of canine progressive ulcerative keratitis.

MATERIALS AND METHODS

Analysis of microbial culture and sensitivity results from dogs with progressive ulcerative keratitis presenting to a UK referral practice between December 2018 and August 2020.

RESULTS

Positive bacterial cultures were obtained from 80/148 (54%) of the canine ulcers sampled with 99 bacterial isolates cultured. Streptococcus canis (n = 29), Pseudomonas aeruginosa (n = 19), and Staphylococcus pseudintermedius (n = 16) were the most common isolates. Pseudomonas aeruginosa was more likely to be isolated whether the ulcer was clinically malacic at the time of sampling (OR = 10.1, p < .001). Ulcers treated prior to culture with fusidic acid were 7.6 times more likely to be positive than those treated with any other antimicrobial(s). Bacterial isolates demonstrated resistance against neomycin (85%), fusidic acid (78%), and tetracycline (68%). Conversely, isolates were most likely to be sensitive to gentamicin (88%), ofloxacin (77%), ciprofloxacin (73%), and chloramphenicol (64%). Antimicrobial combinations of chloramphenicol or gentamicin with a fluoroquinolone (ofloxacin or ciprofloxacin) or chloramphenicol combined with gentamicin were the most effective on in vitro analysis (over 90% susceptibility of all isolates).

CONCLUSION

The most common bacterial species associated with canine progressive ulcerative keratitis in a UK referral population were S. canis, P. aeruginosa, and S. pseudintermedius. Combination antimicrobial therapy is recommended pending culture and sensitivity results given the varied antimicrobial susceptibility profiles and significant bacterial in vitro resistance to antimicrobial monotherapy.

A Multifaceted Presentation of Xerophthalmia in Autistic Patients

We report the manifestations of vitamin A deficiency (VAD) in three children with underlying autism of different stages. These children were under developmental paediatrician follow-up for autism, and the VAD was not detected until these children presented to Ophthalmology screening for varying stages of signs and symptoms. On further assessment, all of our patients have VAD secondary to poor dietary intake, as autistic patients are associated with having selective eating habits. In our case series, we discuss the spectrum of xerophthalmia presentations, which can be mild and can manifest as punctate epithelial erosions to the more blinding complications at the advanced stage of the disease, mainly irreversible optic neuropathy. The primary management is to address the dietary routine coupled with systemic administration of vitamin A.

Multidirectional corneoconjunctival transposition in the treatment of large keratomalacia in 7 dogs and 5 cats

OBJECTIVE

To describe the use of multidirectional corneoconjunctival transposition (CCT) as a surgical treatment for large keratomalacia.

METHOD

A prospective study including dogs and cats initially presenting with keratomalacia larger than 6 × 6 mm and affecting more than half of the corneal thickness. Signalment, concurrent eye diseases, ulcer size, bacterial culture and susceptibility testing results, follow-up, and outcome were recorded. The surgery consisted of harvesting of two or three opposite corneoconjunctival grafts, after removal of the malacic tissue using a square-edge keratectomy. The medical treatment consisted of administration of topical and systemic antibiotics, topical atropine, and N-acetylcysteine. Follow-up examinations were performed at D7, D14, D21, and D28, and then at various time points. The corneal clarity score (CCS) was recorded upon completion of the follow-up period.

RESULTS

Seven dogs and five cats were included. Brachycephalic dogs were overrepresented, with no breed predisposition in cats. Concurrent eye diseases were corneal pigmentation in three dogs, hypopyon in two dogs, nictitating membrane wound in one dog, and corneal perforation in one cat. The size of the keratomalacia ranged from 6 × 6 to 9.5 × 11.5 mm. The short-term complications were suture dehiscence (two of 12) and progression of the keratomalacia (one of 12). The long-term complications were corneal pigmentation (10 of 12), corneal epithelial inclusion cyst (two of 12), and marginal synechiae (one of 12). All animals were sighted at the last follow-up. The median CCS was G3 (range G2-G4).

CONCLUSION

Multidirectional CCT is an effective surgical treatment for large keratomalacia in dogs and cats.

Bilateral Corneal Melting in a Pediatric Patient with Severe Vitamin A Deficiency: A Case Report and Review of Literature

Background

Keratomalacia refers to an ocular destructive dryness of the cornea that results from severe vitamin A deficiency. It is an ocular condition, usually affecting both eyes. It affects infants, children and women of reproductive age. In developing countries, vitamin A deficiency in the diet and associated keratomalacia are a major cause of childhood blindness.

Purpose

To report the clinical finding of a patient with bilateral keratomalacia arising from severe vitamin A deficiency from a malnourished diet.

Patients and Methods

Case report.

Results

A two-year-old female with severe malnutrition presented with 3 weeks of watering and tonic blepharospasm affecting the right and left eyes. She exhibited trichomegaly, severe weight loss, abnormal hairs with complete corneal melt in the right and left eyes and inflamed iris tissue in the right eye. She was treated with high dose vitamin A, but the right eye required evisceration and tarsorrhaphy was done in the left eye.

Conclusion

The visual morbidity associated with xerophthalmia secondary to vitamin A deficiency can be devastating. Diet-induced vitamin A deficiency is prevalent in developing and war-torn countries. A good history taking and review of systems are valuable in evaluating malnourished patients with corneal melt.

Melting corneal ulcers (keratomalacia) in dogs: A 5-year clinical and microbiological study (2014-2018)

OBJECTIVES

To identify bacterial microorganisms associated with canine keratomalacia, review their antimicrobial sensitivity, and evaluate clinical outcomes compared to results of microbial culture.

METHODS

Retrospective analysis of clinical records of dogs diagnosed with a melting corneal ulcer presented to a referral hospital in Hertfordshire, UK between 2014 and 2018.

RESULTS

One hundred and ten melting corneal ulcers were sampled in 106 dogs. The most common pure bacterial isolate was Pseudomonas aeruginosa (n = 26) followed by β-hemolytic Streptococcus (n = 12). Melting corneal ulcers that cultured coagulase-positive Staphylococcus, coliform bacteria, Pasteurella multocida, Enterococcus, and Streptococcus viridans presented in smaller numbers and were analyzed together (n = 16). Multiple cultures were identified in nine cases (n = 9). Forty-seven cultures yielded no bacterial growth (n = 47). The susceptibility to fluoroquinolones remained high with the exception of β-hemolytic Streptococci. There was no significant difference in the ulcer severity at presentation in regard to the cultured bacteria. Overall, 63 eyes (57%) received surgical grafting in addition to medical treatment. In 14 cases (13%), the progression of corneal melting despite medical ± surgical treatment resulted in enucleation. Fifty-seven percent (8/14) of the enucleated eyes cultured pure Pseudomonas aeruginosa isolates. In contrast, all β-hemolytic Streptococcus-associated ulcers healed.

CONCLUSIONS

The most common bacterial species associated with canine keratomalacia were Pseudomonas aeruginosa and β-hemolytic Streptococcus. Because of the variation in antibacterial sensitivity between these two species, bacterial culture and sensitivity testing should be performed in all dogs presenting with keratomalacia. Melting corneal ulcers associated with pure Pseudomonas infection were significantly more likely to result in globe loss than melting corneal ulcers associated with other cultures.

Case Report: Successful Management of Refractory Keratomycosis in an Alpaca Using Penetrating Keratoplasty and Combination Antifungal Therapy (Caspofungin 0.5% and Terbinafine 1%)

Fungal keratitis is a common disease in certain parts of the world and affects several species, including equids, camelids, and homo sapiens, leading to blindness or loss of the eye if the infection is not adequately controlled. Reports of clinical use of antifungals caspofungin and terbinafine are limited across both veterinary and human medical literature. The alpaca presented in this case demonstrates that deep keratomycosis can be caused by Scopulariopsis brevicaulis and Fusarium verticillioides, two previously unreported fungi to cause keratomycosis in camelids. This report demonstrates successful management with a combination of surgery and topical ophthalmic treatment with caspofungin 0.5% solution and terbinafine 1% dermatologic cream, after initially failing treatment with topical voriconazole 1% solution. Combination therapy appears more effective than monotherapy with some fungal organisms, and synergy between antifungal agents is thought to play a role in the success of combination therapy. Surgery to remove the bulk of the fungal infection is especially helpful in cases that fail initial medical therapy.

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.

Descemetocele

A corneal descemetocele, the anterior herniation of an intact Descemet membrane through an overlying stromal defect, is a rare, but serious outcome of progressive corneal ulceration and mandates urgent intervention owing to the imminent risk of perforation. Various ocular and systemic abnormalities that can lead to the formation of descemetocele include microbial keratitis, neurotrophic keratopathy, dry eye disorders, and corneal inflammation associated with immune-mediated disorders. The primary aim of management of a descemetocele remains prompt restoration of ocular integrity to prevent the rupture of the Descemet membrane and further complications. Medical therapy is instituted immediately while deciding on the most suitable operative modality for an individual case. Commonly available treatment options include therapeutic bandage contact lenses, tissue adhesives, amniotic membrane transplantation, corneal patch grafts, penetrating or lamellar keratoplasty, and conjunctival flaps. Infrequently, platelet-rich fibrin membrane grafting and umbilical cord patch transplantation have also been tried with success. The surgical strategy and the outcome are commonly determined by the size, location, and etiology of descemetoceles. Despite the availability of all these treatment options, ambiguity remains about management. We review the available literature on pathogenesis, causes, presentation, differential diagnoses, and management of this disorder and also discuss our experience.

Equine ulcerative keratitis with furrow: A review of the outcomes of 72 cases from 1987 to 2015

BACKGROUND

Ulcerative keratitis with peripheral furrow formation is a poorly-described condition which has been associated with a grave prognosis due to rapid necrosis of the cornea.

OBJECTIVE

To describe the infectious aetiologies associated with furrow-forming ulcerative keratitis, its overall clinical course and the efficacy of medical and surgical intervention in horses.

STUDY DESIGN

Retrospective clinical case series.

METHODS

Medical records of 72 horses which presented with furrow-forming ulcerative keratitis at the University of Florida between 1987 and 2015 were reviewed.

RESULTS

Seventy-two horses (72 eyes) with furrow-forming ulcerative keratitis were treated at the University of Florida between 1987 and 2015. Of these, a definitive aetiologic diagnosis was available for 37 eyes. Ten of 37 eyes (27%) were diagnosed with fungal keratitis based on cytology of corneal scraping, culture, histopathology and/or fungal PCR. Fourteen of 37 eyes (38%) were diagnosed with a mixed fungal and bacterial keratitis. Thirteen of 37 eyes (35%) were diagnosed with bacterial keratitis. Overall, 26 of 72 total eyes were treated with medical therapy alone (36%). Forty-six of 72 eyes were treated medically and surgically (64%). Of the 26 eyes which received medical therapy, 20 healed with a positive visual outcome (77%) and 6 eyes were non-visual (23%). Of the 46 eyes which received surgical intervention, 40 healed with a positive visual outcome (87%), while six eyes were non-visual (13%). Altogether, 60 of 72 eyes healed with a positive visual outcome following medical or surgical treatment of furrow-forming ulcerative keratitis (83%). Twelve of 72 eyes failed treatment (17%), with six eyes requiring enucleation and six globes becoming phthisical after treatment.

MAIN LIMITATIONS

Inconsistencies in available medical record data due to the large span of time (1987-2015) are inherent in this retrospective study, along with gradual evolution of corneal surgical techniques and medical therapies over the decades.

CONCLUSIONS

Furrow-forming ulcerative keratitis was associated with a positive visual outcome in 83% of horses treated at the University of Florida between the years 1987 and 2015. Furrow formation may be associated with either fungal or bacterial infection.

Capnocytophaga keratitis in dogs: clinical, histopathologic, and microbiologic features of seven cases

OBJECTIVE

To describe the clinical, microbiologic, and histopathologic features of Capnocytophaga keratitis in dogs.

ANIMALS STUDIED

Seven dogs with naturally acquired Capnocytophaga keratitis.

PROCEDURES

Medical records of dogs with a clinical diagnosis of keratitis and corneal cultures positive for Capnocytophaga spp. were reviewed. Dog signalment, medical history, clinical findings, and diagnostic assay results were recorded.

RESULTS

Breeds included Boston terrier (n = 3 dogs), Rat terrier (n = 2), and single cases of mixed breed and Pug. All dogs examined had expansive corneal ulceration involving the majority of the corneal surface. Marked corneal infiltrates, keratomalacia, and hypopyon were present. Progression of corneal disease was rapid with extensive dissolution of the corneal stroma. Corneal lesions progressed to catastrophic perforations within 24 h of the initial examination in three dogs, requiring enucleation. One globe was enucleated after failure to resolve with long-term medical therapy. Globes and vision were retained in three dogs following aggressive medical therapy (two dogs) or 360° conjunctival graft surgery (one dog). Capnocytophaga cynodegmi, Capnocytophaga canimorsus, or unspeciated Capnocytophaga spp. were cultured from corneal samples of all dogs. Long, thin, gram-negative rods were present during cytological evaluation of the cornea in some dogs. Histopathologic evaluation of enucleated globes revealed severe and diffuse neutrophilic and collagenolytic keratitis.

CONCLUSIONS

Capnocytophaga keratitis is a severe, rapidly progressive corneal infection in dogs that is associated with diffuse corneal involvement, extensive keratomalacia, and a relatively poor prognosis. Clinical features of canine Capnocytophaga keratitis are similar to human cases of this infection.

Phasing out of the Universal Mega Dose of Vitamin-A Prophylaxis to Avoid Toxicity

Childhood blindness due to corneal ulceration was prevalent among poor Indian children. To tackle this situation, the National Institute of Nutrition (NIN), Hyderabad, India, Vitamin-A (Vit-A) prophylaxis programme was launched nationally in 1970 after field testing. Research of Indian Council for Medical Research (ICMR) documented that prevalence of Vit-A deficiency signs such as Bitot's spot decreased among children, over a period of time. However, this decrease cannot be ascertained is due to mass Vit-A prophylaxis programme. This is because coverage was low and patchy. Improved nutrition status, wider vaccination coverage, increased rate in breast feeding and improvement of healthcare services played a crucial role. Rather many studies revealed that (mass prophylaxis to the child who is having adequate Vit-A level) it may be harmful to certain group of children as a result of acute toxic symptoms. High dose of Vit-A is capable of loss of bone density-hence retarded growth may be observed in susceptible individuals. To tackle this issue food based approach should be promoted (which includes breast feeding) along with timely measles vaccination. The children who have signs of Vit-A deficiency (e.g. night blindness, xeropthalmia, Bitot's spot) or post measles children should receive Vit-A in age specific daily doses for two weeks along with Vit-A rich food, like green leafy vegetables, red palm oil, liver etc. Public spirited citizens, together with scientific community in India, should discourage this “one size fit to all” approach. It will not only avoid the ill effects of high dose of Vit-A but also it will help us optimal utilization of health resources in a resource poor country like India.

Corneal collagen cross-linking (CXL) for the treatment of melting keratitis in cats and dogs: a pilot study

OBJECTIVE

UV-A/riboflavin cross-linking (CXL) of corneal collagen fibers is an established, highly promising therapy for corneal melting in physician-based ophthalmology. A prospective pilot study was conducted to demonstrate proof of principle of this novel method for the treatment of melting corneal ulcers in dogs and cats.

PROCEDURES

After obtaining owner consent, CXL was performed in three cats and three dogs with corneal melting, which either affected the entire corneal surface or was resistant to conventional antibiotic and anticollagenolytic therapy, and affected parts or all of the corneal surface. Medical therapy was continued in all patients. The available follow-up ranged from 2 to 22.5 months and involved slit-lamp examination, fluorescein staining, and photographic documentation during all rechecks.

RESULTS

Surgical stabilization of the cornea was not necessary in any case, because progression of corneal melting was arrested in all cases within 1-20 days of CXL treatment. Corneal re-epithelization occurred within 7-40 days in all eyes. At 40 days after CXL, all eyes presented a quiescent corneal state without signs of active inflammation and with beginning scar formation. The complications observed in three of the six animals included a corneal sequestrum, superficial corneal stromal pigmentation, and bullous keratopathy.

CONCLUSIONS

This study shows the feasibility of CXL to treat progressive corneal melting in veterinary patients. CXL may represent a cost-efficient and safe alternative therapy in the treatment for corneal melting in veterinary ophthalmology. More investigations comparing the effectivity and complication rate of CXL to those of standard medical treatment are necessary.

Keratoplasty for keratomalacia in preschool children

AIM

To study the results of surgical management of keratomalacia in children.

METHODS

A clinical case series of all children with keratomalacia, admitted to an Indian centre during the period from June 2000 to June 2001 is presented. The parameters evaluated were demographic data, systemic associations, and results of medical and surgical intervention.

RESULTS

29 children with keratomalacia ranging from 2 months to 5 years of age (mean 1.8 (SD 1.4) years) were included in the study. All children belonged to families of lower socioeconomic status. 27 patients (93.1%) had not been immunised at all. The systemic diseases precipitating the onset of keratomalacia included measles (41.37%), pneumonia (31.03%), and acute diarrhoea (37.93%). 36 eyes (66.7%) had total corneal melting and 11 (20.3%) eyes had paracentral corneal melting. In 15 eyes (27.8%) an emergency tectonic penetrating keratoplasty was performed of which only five grafts (33.3%) remained clear at a mean follow up of 7.3 (6.8) months (range 3-24 months). Seven eyes underwent optical penetrating keratoplasty, of which four grafts (57.14%) remained clear at a mean follow up of 6.4 (3.6) months (range 3-12 months). None of these could achieve a visual acuity better than 6/60.

CONCLUSIONS

Corneal grafting surgery in keratomalacia is associated with poor visual outcome.