Ophthalmology in horses encompasses the study and treatment of eye disorders and diseases affecting equine species. Equine ophthalmic conditions can range from conjunctivitis and corneal ulcers to more complex issues such as uveitis and cataracts. These conditions can impact a horse's vision and overall well-being. Diagnostic techniques in equine ophthalmology include visual examinations, fluorescein staining, and advanced imaging methods like ultrasonography. Treatment approaches vary depending on the specific condition and may involve medication, surgical intervention, or supportive care. This page compiles peer-reviewed research studies and scholarly articles that explore the anatomy, pathology, diagnostics, and treatment modalities related to equine ophthalmology.
Wada S, Ode H, Hobo S, Niwa H, Katayama Y, Takatori K.To describe a case of superficial keratomycosis caused by Mortierella wolfii (M. wolfii) in a horse. Methods: A thoroughbred filly was presented with painful right eye of 2 days' duration. A superficial corneal ulcer was observed ventrally together with multifocal punctuate opacities axially. Samples were collected by swabbing and scraping the ulcerated lesion and submitted for microbiologic and cytologic examination. Results: Microscopic evaluation of debrided corneal tissue revealed the presence of nonseptate fungal hyphae, and culture of a corneal swab yielded fungal growth. Medical treat...
Sandmeyer LS, Bellone RR, Archer S, Bauer BS, Nelson J, Forsyth G, Grahn BH. To determine if congenital stationary night blindness (CSNB) exists in the Miniature Horse in association with leopard complex spotting patterns (LP), and to investigate if CSNB in the Miniature Horse is associated with three single nucleotide polymorphisms (SNPs) in the region of TRPM1 that are highly associated with CSNB and LP in Appaloosas. Methods: Three groups of Miniature Horses were studied based on coat patterns suggestive of LP/LP (n=3), LP/lp (n=4), and lp/lp genotype (n=4). Methods: Horses were categorized based on phenotype as well as pedigree analysis as LP/LP, LP/lp,...
Auer U, Moens Y.The production of a central eye to ease surgical access for intraocular surgery is generally dependent on the depth of anesthesia. The aim of this study was to evaluate the eyeball position under muscle relaxation with rocuronium during general anesthesia. Methods: Twenty horses, body weight 480 ± 62 kg; age 12.6 ± 6.2 years (mean ± SD) were anesthetised for various ophthalmic surgeries. Horses were premedicated with acepromazine, xylazine, and butorphanol intravenously and anesthesia induced with ketamine and diazepam. Anesthesia was maintained with isoflurane in 100% oxyge...
Plummer CE, Ramsey DT.To determine the incidence of ocular abnormalities in miniature horses. Methods: Descriptive study. Methods: Fifty-three miniature horses. Methods: Ophthalmic examinations were performed using diffuse and focal illumination, slit-lamp biomicroscopy and indirect ophthalmoscopy. Coat color, mane and tail color, age and gender were recorded with results of ophthalmic examination. Results: Ocular abnormalities detected most frequently consisted of cysts arising from the posterior iris, ciliary body, and peripheral retina, curvilinear streaks of retinal pigmented epithelium extending from the perip...
Komáromy AM, Rowlan JS, La Croix NC, Mangan BG.To describe the clinical phenotype and genetics of equine Multiple Congenital Ocular Anomalies (MCOA) syndrome in PMEL17 (Silver) mutant ponies. Methods: Five presumably unrelated ponies. Methods: The ponies were examined under field conditions in their barn by slit lamp biomicroscopy, indirect ophthalmoscopy, and applanation tonometry. Blood was collected and genomic DNA extracted for MCOA genotyping using the PMEL17ex11 marker. Results: One pony solely presented with temporal ciliary body cysts, suggestive of the less severe Cyst phenotype of MCOA; the animal was heterozygous at the MCOA loc...
Andersson LS, Lyberg K, Cothran G, Ramsey DT, Juras R, Mikko S, Ekesten B, Ewart S, Lindgren G.The syndrome Multiple Congenital Ocular Anomalies (MCOA) is the collective name ascribed to heritable congenital eye defects in horses. Individuals homozygous for the disease allele (MCOA phenotype) have a wide range of eye anomalies, while heterozygous horses (Cyst phenotype) predominantly have cysts that originate from the temporal ciliary body, iris, and/or peripheral retina. MCOA syndrome is highly prevalent in the Rocky Mountain Horse but the disease is not limited to this breed. Affected horses most often have a Silver coat color; however, a pleiotropic link between these phenotypes is y...
Gornik K, Moore P, Figueiredo M, Vandenplas M.Human corneal cells have detectable levels of TLRs 1-10. TLRs 2 and 4 are the major corneal receptors, recognizing the PAMPs associated with fungal invasion in humans. The conjunctiva and limbus contain TLRs 2, 4, and 9. Our purpose was to determine the expression of TLRs 2, 3, 4, 6, 9, and MD-2 in the normal equine cornea, conjunctiva, and limbus. Methods: Corneal, limbal, and conjunctival tissues were collected from seven euthanized horses having no evidence of ocular disease. RNA extraction with DNase-1 digestion was performed followed by RT-PCR to determine expression of TLRs 2, 3, 4, 6, 9...
Pinard CL, Basrur PK.To characterize the ocular anomalies, determine their recurrence in families and assess the mode of inheritance of the most prevalent anomalies through pedigree analysis in a herd of Exmoor ponies. Methods: Thirty Exmoor ponies residing in south-western Ontario, Canada. Methods: Ophthalmic examination was performed using direct ophthalmoscopy, slit-lamp biomicroscopy and indirect ophthalmoscopy, pre- and post-pupillary dilation. Following compilation of ocular findings, pedigree analysis was conducted to assess the recurrence pattern of specific anomalies in families and the data were tested f...
Westermeyer HD, Hendrix DV, Ward DA, Cox SK.To determine ocular tissue drug concentrations after topical ocular administration of 0.3% ciprofloxacin and 0.5% moxifloxacin in ophthalmologically normal horses. Methods: 24 ophthalmologically normal adult horses. Methods: 0.3% ciprofloxacin and 0.5% moxifloxacin solutions (0.1 mL) were applied to the ventral conjunctival fornix of 1 eye in each horse as follows: group 1 (n = 8) at 0, 2, 4, and 6 hours; group 2 (8) at 0, 2, 4, 6, and 10 hours; and group 3 (8) at 0, 2, 4, 6, 10, and 14 hours. Tears, cornea, and aqueous humor (AH) were collected at 8, 14, and 18 hours for groups 1, 2, and 3, r...
Berzina I, Trumble NS, Novicki T, Sharkey LC.An 11-year-old American Saddlebred gelding was presented for evaluation of a nonpainful subconjunctival mass involving the lateral canthus of the left eye. Other findings included a central corneal scar and a small central cataract of the lens in the left eye. Fine-needle aspiration of the mass was performed and cytologic examination revealed marked pyogranulomatous inflammation with intralesional fungal hyphae, consistent with mycetoma. The fungal structures were elongated and characterized by nonstaining walls; several bulbous yeast-like structures were also observed. The mycetoma was surgic...
Labelle AL, Hamor RE, Macneill AL, Lascola KM, Breaux CB, Tolar EL.There is little scientific information available about the ability of ocular disease to cause a systemic inflammatory response. Horses are frequently affected with ocular disease and ensuring their systemic health prior to performing vision saving surgery under anaesthesia is essential for the successful treatment of ophthalmic disease. Objective: Ocular disease will cause elevations in the concentration of the acute phase proteins fibrinogen and serum amyloid A in peripheral blood. Methods: Whole blood and serum samples were obtained from 38 mature horses with ulcerative keratitis or uveitis ...
Arenas-Gamboa AM, Mansell J.Haemangiosarcomas (HSAs) are malignant tumours of endothelial cell origin. Epithelioid HSA is a variant of the histologically conventional HSA that has little or no morphological evidence of a vascular origin and has been reported rarely in domestic animals. The following report documents six cases of equine epithelioid HSA occurring in the ocular tissues of horses with a mean age of 19.8 years at the time of diagnosis. Microscopically, all of the lesions consisted of solid sheets or cords of epithelioid cells with rare narrow clefts or small spaces containing erythrocytes that were often the ...
Clode A, Davis J, Davidson G, Salmon J, Lafevers H, Gilger B.To determine the transcorneal penetration and systemic absorption of a compounded 0.2% terbinafine solution following repeated topical administration to normal equine eyes. Sample population Six healthy adult horses with normal ocular examinations. Methods: One eye of each horse received 0.2 mL of a compounded 0.2% terbinafine solution every 4 h for seven doses. During the 1 h following administration of the final dose, multiple peripheral blood samples were obtained, and a single aqueous humor (AH) sample was collected at the end of the hour. AH and plasma concentrations of terbinafine wer...
Mathes RL, Paige Carmichael K, Peroni J, Anthony Moore P.A 5-year-old Draft Horse gelding presented for evaluation of a large, fleshy, ulcerated third eyelid mass OD of 3 weeks duration. Complete ophthalmic examination, ocular ultrasound and skull radiographs revealed a large soft-tissue mass involving the entire third eyelid OD and extending into the ventral right orbit to the level of the globe equator. No other abnormalities were noted on physical or ophthalmic examination. Surgical removal via exenteration was performed 3 months after initial presentation. A lacrimal adenocarcinoma of the third eyelid was diagnosed based on histopathology. Concu...
Monclin SJ, Farnir F, Grauwels M.Tetracaine hydrochloride (THCl) has been reported to cause irritation in dogs. In man, some topical anaesthetics have been shown to disrupt the tear film. Tear break-up time (TBUT) is a useful test allowing an assessment of the quality of the precorneal tear film. Only one TBUT value has been reported in horses with no information on the technique used. Objective: To provide a method for performing the TBUT in horses and to report any side effects of a single application of THCl in clinically normal horses, particularly on the stability of the tear film. Methods: In Study 1, one drop of 0.5 or...
Spiess BM.Equine recurrent uveitis (ERU) has always been and still is an important disease with a significant impact on the horse industry in Europe, with a prevalence of 8-10%. The need to understand and manage the disease has spurred the development of veterinary ophthalmology in general, although the aetiology of the disease remains the subject of intense discussion. It is most probably an autoimmune disease triggered, at least in Europe, in the majority of cases by Leptospira spp. The therapy of ERU has evolved over the centuries from various methods of bloodletting to rational medical therapy using...
Hughes KJ.Ocular manifestations may develop in many systemic diseases of horses; however, signs may not be observed unless ophthalmological examination is specifically undertaken. Recognition and assessment of ocular lesions in horses with systemic disease is desirable to facilitate diagnosis and determination of treatment options and diagnosis for both the underlying systemic disease and ocular manifestations. The purpose of this article is to review systemic diseases of horses that may have ocular signs as part of the disease process. Systemic diseases are discussed in categories of pathways for devel...
Gilger BC.Equine recurrent uveitis (ERU) is a common disease in horses in the USA. There have been many advances in the treatment of ERU; however, frequent misdiagnosis of ERU occurs in cases of primary corneal or uveal disease. It is critical to remember that primary uveitis (i.e. one bout of inflammation) is a different disease to ERU, which is an immune mediated recurrent uveitis. Standard symptomatic anti-inflammatory therapy is effective to control most cases of ERU; however, some horses require advanced therapy, such as placement of drug delivery devices or removal of the vitreous, when they fail ...
Mayhew IG.Evaluation of horses for eye problems and for suspected impairment of visual acuity often requires a thorough neuroophthalmic examination to be conducted. Along with a full ophthalmic evaluation, the results of such an examination should indicate the likely site of any lesion(s) accounting for blindness, miosis, mydriasis, anisocoria, Horner's syndrome, strabismus, facial paralysis and facial spasm, nystagmus and other signs of vestibular disease, and cerebellar disorders, that may be present. Such a thorough examination with guidance for correct interpretation of findings is given here.
McMullen RJ, Utter ME.The purpose of this review is to discuss the evolution of equine cataract surgery over the past 50 years to its current stage. Equine cataract surgery is performed similarly compared with the techniques used in human ophthalmology and in other veterinary species. However, enough differences exist to make surgical lens removal and intraocular lens implantation in the horse an intrinsically unique endeavour. Due to the size of the adult equine globe, the introduction of species-specific instrumentation has provided the cornerstone to many of the changes made regarding surgical technique over the...
Nell B, Walde I.Diseases of the vitreous, fundus and optic nerve are described and illustrated according to their ophthalmological appearance. Vitreal alterations are commonly of developmental, degenerative, age related, traumatic or inflammatory origin and of minor clinical relevance. In contrast, those affecting the fundus, may be accompanied by visual deficits or blindness. Fundic lesions of inflammatory (multifocal or peripapillary chorioretinitis, haemorrhage, retinal detachment) and traumatic origin have to be differentiated from congenital (congenital stationary night blindness, colobomatous defects, r...
Giuliano EA.Neoplastic adnexal disease represents one of the most frequently encountered and therapeutically challenging ophthalmic problems of horses. This paper reviews current concepts in equine periocular neoplasia. Specifically, a literature-based review of the aetiopathogenesis of the most common tumours to affect the equine eyelid (squamous cell carcinoma, sarcoid, melanoma and lymphosarcoma) is provided. Current and emerging treatment modalities, including photodynamic therapy, are reviewed.
Wilkie DA.Understanding and awareness of equine glaucoma has significantly improved in recent years. The availability of portable tonometers and veterinarian/owner awareness has increased the frequency of glaucoma as a clinical diagnosis. A variety of medications for the medical management of equine glaucoma have been evaluated and the addition of lasers has improved the surgical treatment of equine glaucoma. Despite this, equine glaucoma is an insidious and painful disease that probably remains under diagnosed and often results in blindness in the affected eye.
Gilger BC, Wilkie DA, Clode AB, McMullen RJ, Utter ME, Komaromy AM, Brooks DE, Salmon JH.To determine the long-term efficacy, complications, and duration of effect of a cyclosporine (CsA) suprachoroidal implant (CSI) in horses with equine recurrent uveitis (ERU). Methods: Horses with ERU were treated with a 6-mm diameter, 25 mg, reservoir matrix CsA implant in the deep sclera adjacent to the suprachoroidal space. Horses with follow-up >1 year were examined for frequency of uveitis episodes, complications, and vision at last recheck. Results: Data from 151 eyes of 133 horses from the USA and Europe that had CsA devices implanted for ERU were reviewed. Follow-up time ranged from 13 ...
Malalana F, Knottenbelt D, McKane S.Ocular lesions in horses, confirmed as squamous cell carcinoma, were treated topically with mitomycin C. Fourteen horses with confirmed ocular squamous cell carcinoma, three of which were affected bilaterally, were included in the study. Eight of the affected eyes were treated topically with mitomycin C alone; in the other nine eyes, the tumours were surgically removed and topical treatment with mitomycin C was then applied. The treatment protocol consisted of 0.2 ml of 0.04 per cent mitomycin C instilled into the conjunctival sac of the affected eye, every six hours, in rounds of seven days o...
Mathes RL, Reber AJ, Hurley DJ, Dietrich UM.To evaluate the effects of topical antifungal drugs and delivery vehicles on the morphology and proliferation rate of cultured equine keratocytes. Methods: 16 corneas obtained from 8 apparently ophthalmologically normal horses < 0.5 hours after euthanasia for reasons unrelated to the study. Methods: Primary cultures of equine keratocytes were obtained from corneal stroma and were exposed to several concentrations of 3 commonly used, topically applied antifungals: natamycin, itraconazole, and miconazole. In addition, effects of drug delivery vehicles DMSO, benzalkonium chloride, and carboxym...
Vanderstraeten E, Bogaert L, Bravo IG, Martens A.Squamous cell carcinoma (SCC) represents the most common malignant tumour of the eye and external genitals in horses. Comparable to humans, papillomaviruses (PV) have been proposed as etiological agents of cancer in horses and recently, Equine papillomavirus type 2 (EcPV2) has been identified in genital SCCs. Hitherto it had never been demonstrated in ocular SCCs. The first goal of this study was to determine the prevalence of EcPV2 DNA in tissue samples from equine genital and ocular SCCs, genital papillomas and penile intraepithelial neoplasia (PIN) lesions, using EcPV2-specific PCR. The sec...
Reinstein SL, Lucio-Forster A, Bowman DD, Eberhard ML, Hoberg EP, Pot SA, Miller PE.A 4-year-old Hanoverian gelding was evaluated because of a mobile worm-like structure in the right eye. Results: Ophthalmologic examination of the right eye revealed a white, thin, coiled, mobile parasite, which was presumed to be a nematode, located in the ventral portion of the anterior chamber of the eye; there also were vitreal strands located temporally and inferiorly near the margin of the pupil. Results of ophthalmologic examination of the left eye were unremarkable. Results: The horse was treated with a neomycin-polymyxin B-dexamethasone ophthalmic solution applied topically (1 drop, q...
Sindak N, Kandemir L, Yertürk M, Biricik HS.To determine physiologic levels of tear production in Arabian (AH) and throughbred horses (TH) by using phenol red thread test (PRT). Methods: The study was performed on 16 AH and 14 TH, ranging from 2.5 to 24 years of age, housed in a stable situated in the Sanliurfa of Turkey. Methods: For the measurement of PRT, the strip was placed under the lower eyelid approximately one-third the distance from the temporal to nasal canthus and left for 15 s. The length of the wet area was measured in mm and compared among breed, sex, and age groups and between eyes of both sides. Results: The mean length...
Ramsey DT, Whiteley HE, Gerding PA, Valdez RA.An 11-year-old Quarter Horse gelding was evaluated because of a persistent, raised band of 1- to 2-mm subepithelial plaques of the left cornea. Cytologic examination of corneal scrapings revealed numerous eosinophils and segmented neutrophils, with few mast cells, plasma cells, and lymphocytes. Bacteriologic culture yielded sparse growth of alpha-hemolytic Streptococcus and Staphylococcus spp. Histologically, the plaques consisted of subepithelial foci of fragmented and degenerated collagen fibers infiltrated by eosinophils and neutrophils, with few lymphocytes, plasma cells, and macrophages. ...
Chandler KJ, Billson FM, Mellor DJ.Ophthalmic lesions were detected in 67 of 83 horses and ponies aged 15 years or more. Degeneration of the vitreous, followed by senile retinopathy, were the most common lesions and both of them became more common with advancing age, although few of the owners reported disturbances of vision in their animals.
Leigh H, Gozalo-Marcilla M, Esteve V, Gutiérrez Bautista ÁJ, Martin Gimenez T, Viscasillas J.Standing surgery in horses combining intravenous sedatives, analgesics and local anaesthesia is becoming more popular. Ultrasound guided (USG) peribulbar nerve block (PB) has been described in dogs and humans for facial and ocular surgery, reducing the risk of complications versus retrobulbar nerve block (RB). Objective: To describe a technique for USG PB in horse cadavers. Methods: Landmarks and PB technique were described in two equine cadaver heads (Phase 1), with computed tomography (CT) imaging confirming contrast location and spread. In Phase 2, ten equine cadaver heads were randomised t...
Hacker DV, Moore PF, Buyukmihci NC.In 4 horses with ocular angiosarcomas, the common characteristics were that all horses were aged, and the neoplasms developed initially on conjunctival surfaces, grew slowly, and metastasized despite excision and radiation treatment. Histopathologically, the neoplasms were of 2 types: a capillary pattern of scant stroma and endothelial-lined vascular channels, and a solid pattern composed of sheets of pleomorphic cells with hyperchromatic nuclei and poorly defined cytoplasmic borders. Definitive diagnosis was made by use of factor VIII:RAg, which stained the tissues intensely.
Turner AG.A discussion of ocular conditions of foals with an emphasis on congenital and inherited disorders is presented. An understanding of the normal postnatal development of the eye and adnexae is important. Recognition of inherited abnormalities is essential when giving advice on breeding suitability, and prompt attention or referral of deteriorating ocular conditions in foals ensures the best outcome for future use. Congenital conditions may be recognized for the first time in older animals during their first thorough eye examination.
Brünott A, Boevé MH, Velden MA.To describe the clinical symptoms of 10 cases of superficial nonhealing corneal ulcers in horses and to evaluate the results of grid keratotomy in these patients. Methods: Retrospective study. Methods: Ten horses with superficial nonhealing corneal ulceration in one eye. Methods: The signalment, history and clinical symptoms are reported of 10 patients with superficial nonhealing corneal ulcers during the period from August 2003 to February 2005. Grid keratotomy was performed in all cases. In addition, the surgical procedure of grid keratotomy and response to therapy are described. Results: Ho...
Rebhun WC.This article reviews options in dealing with tumors of the cornea and conjunctiva, nictitating membrane neoplasms, and eyelid neoplasms. Orbital tumors, optic nerve and other intraocular tumors are also discussed.
Yamagata M, Wilkie DA, Gilger BC.Eosinophilic keratoconjunctivitis was diagnosed in 7 horses at The Ohio State University between 1976 and 1994. All horses had moderate-to-severe blepharospasm, chemosis, and conjunctival hyperemia; epiphora; and extensive yellow-to-white caseous mucoid discharge. Corneal ulcers associated with this disease were perilimbal and extended centrally. All ulcers were covered with a white necrotic plaque firmly attached to the underlying cornea. Other ophthalmic abnormalities were not detected. Corneal scrapings examined cytologically contained numerous eosinophils interspersed between epithelial ce...
Westermeyer HD, Hendrix DV, Ward DA, Cox SK.To determine ocular tissue drug concentrations after topical ocular administration of 0.3% ciprofloxacin and 0.5% moxifloxacin in ophthalmologically normal horses. Methods: 24 ophthalmologically normal adult horses. Methods: 0.3% ciprofloxacin and 0.5% moxifloxacin solutions (0.1 mL) were applied to the ventral conjunctival fornix of 1 eye in each horse as follows: group 1 (n = 8) at 0, 2, 4, and 6 hours; group 2 (8) at 0, 2, 4, 6, and 10 hours; and group 3 (8) at 0, 2, 4, 6, 10, and 14 hours. Tears, cornea, and aqueous humor (AH) were collected at 8, 14, and 18 hours for groups 1, 2, and 3, r...
Meister U, Görig C, Murphy CJ, Haan H, Ohnesorge B, Boevé MH.Phacoemulsification and intraocular lens (IOL) implantation during cataract surgery in horses occur with increasing frequency. To reduce the postoperative refractive error it is necessary to determine the proper IOL power. In the present study retinoscopy, keratometry and ultrasonographic biometry were performed on 98 healthy equine eyes from 49 horses. The refractive state, corneal curvature (keratometry) and the axial location of all optical interfaces (biometry) were measured. The influences of breed, height at the withers, gender and age on values obtained and the comparison between the le...
Mathes RL, Reber AJ, Hurley DJ, Dietrich UM.To evaluate the effects of topical antifungal drugs and delivery vehicles on the morphology and proliferation rate of cultured equine keratocytes. Methods: 16 corneas obtained from 8 apparently ophthalmologically normal horses < 0.5 hours after euthanasia for reasons unrelated to the study. Methods: Primary cultures of equine keratocytes were obtained from corneal stroma and were exposed to several concentrations of 3 commonly used, topically applied antifungals: natamycin, itraconazole, and miconazole. In addition, effects of drug delivery vehicles DMSO, benzalkonium chloride, and carboxym...
Massa KL, Murphy CJ, Hartmann FA, Miller PE, Korsower CS, Young KM.To determine the diagnostic value of aerobic microbial culture and cytologic evaluation of corneal specimens in the diagnosis of infectious ulcerative keratitis (IUK). Methods: Prospective study. Methods: 48 animals (26 dogs, 13 horses, 7 cats, 1 bird, and 1 llama) with corneal ulcers. Methods: Scrapings from corneal ulcers were examined cytologically. Corneal swab specimens were submitted for microbial culture. Animals were grouped according to whether they had been receiving antimicrobials at the time of admission. Results: Of the 38 animals receiving antimicrobials, 19 had positive results ...
Chalder RH, Knott T, Rushton JO, Nikolic-Pollard D.To identify temporal changes in antimicrobial resistance of ocular surface bacteria isolated from clinically symptomatic equine eyes in the South West of the UK. Methods: Retrospective. Methods: Clinical and laboratory records of horses treated for suspected bacterial ocular surface disease (ulcerative and non-ulcerative) at a single facility between January 2011 and December 2019 were reviewed. Cases were included if they underwent ocular surface sampling, aerobic bacterial culture, and antimicrobial susceptibility testing. Cases were split into two time periods based on when sampling occurre...
Ben-Shlomo G.Fundus is an anatomic term referring to the portion of an organ opposite from its opening, and the fundus of the eye is the back portion of the posterior segment of the globe, including the optic nerve, retina, and choroid. Clinically, the fundus can be visualized by direct or indirect ophthalmoscopy. Understanding the normal anatomy and appearance of the equine fundus is crucial for differentiating normal variations from abnormalities. This article reviews the normal anatomy and appearance of the equine fundus and discusses basic and advanced examination techniques. It also discusses common f...
Baumgartner WA, Storey ES, Paulsen DB.Intraocular choristomas are rare anomalies in domestic animals and are often associated with multiple ocular malformations. A Thoroughbred foal presented for ocular abnormalities and was diagnosed with microphthalmia, corneal dermoids, severe anterior segment dysgenesis (including glandular choristomas), aphakia, retinal dysplasia, and optic nerve hypoplasia. Morphological, histochemical, and immunohistochemical comparisons were made between ocular choristomatous tissues from this foal and lacrimal gland, third eyelid gland, nasopharynx, trachea, and lacrimal sac/nasolacrimal duct from normal ...
Scotty NC, Brooks DE, Schuman Rose CD.To evaluate the in vitro efficacy of an ophthalmic drug combination against common corneal pathogens of horses. Methods: Representative isolates of 3 bacterial and 2 fungal corneal pathogens of horses. Methods: Pathogens were subjected to minimum inhibitory concentration (MIC) testing of a drug combination that consisted of equal volumes of natamycin 3.33%, tobramycin 0.3%, cefazolin 5.5%, and equine serum. Proteinase inhibitory activity of the drug combination was assessed by use of a fluorescence microplate assay with gelatin and collagen I as substrates. The MICs of the drug combination wer...
Davis K, Carter R, Tully T, Negulescu I, Storey E.To evaluate aqueous humor viscosity in the raptor, dog, cat, and horse, with a primary focus on the barred owl (Strix varia). Methods: Twenty-six raptors, ten dogs, three cats, and one horse. Methods: Animals were euthanized for reasons unrelated to this study. Immediately, after horizontal and vertical corneal dimensions were measured, and anterior chamber paracentesis was performed to quantify anterior chamber volume and obtain aqueous humor samples for viscosity analysis. Dynamic aqueous humor viscosity was measured using a dynamic shear rheometer (AR 1000 TA Instruments, New Castle, DE, US...
Brooks DE, Plummer CE, Mangan BG, Ben-Shlomo G.To describe clinical findings in equine subepithelial keratomycosis (SEK). Methods: Retrospective medical records study. Methods: Medical records of horses that had subepithelial keratomycosis (SEK) at the University of Florida Veterinary Medical Center from 2007 to 2011 were reviewed. Methods: Data collected from the medical records included signalment, clinical descriptions of ocular lesions, diagnostic techniques, and therapeutic outcomes. Results: Twenty-one horses, consisting of three Quarter horse geldings, two Morgan geldings, one Morgan mare, two Arabian mares, three Arabian geldings, ...
Peraza J, Hector RC, Lee S, Terhaar HM, Knych HK, Wotman KL.Acetaminophen (paracetamol) is increasingly used to treat painful conditions in horses but its ocular penetration has not been studied. Objective: To determine whether orally administered acetaminophen penetrates the aqueous humour of the normal equine eye and report an aqueous humour:serum acetaminophen concentration ratio in horses. Methods: In vivo experiment. Methods: Six privately owned horses with normal ophthalmic examinations weighing 568 ± 65 kg (mean ± standard deviation) and aged 11 ± 4 years were given 20 mg/kg acetaminophen orally every 12 h for a total of s...
Bellone RR.Advances in equine genetics and genomics resources have enabled the understanding of some inherited ocular disorders and ocular manifestations. These ocular disorders include congenital stationary night blindness, equine recurrent uveitis, multiple congenital ocular anomalies, and squamous cell carcinoma. Genetic testing can identify horses with or at risk for disease and thus can assist in clinical management. In addition, genetic testing can identify horses that are carriers and thus can inform breeding decisions. Use of genetic tests in management and breeding decisions should aid in reduci...
Lassaline-Utter M, Cutler TJ, Michau TM, Nunnery CM.To review the signalment, clinical characteristics, and outcome of horses with nonhealing corneal ulcers treated with diamond burr debridement (DBD); and to evaluate the role of ulcer duration, size and location, and bandage contact lens (BCL) placement on healing. Methods: From January 2012-April 2013, 60 horses were diagnosed with ulcers classified as nonhealing based on the presence of raised epithelial margins and duration of at least 7 days. Methods: Retrospective record review. Results: Average age of included horses was 14.68 years, SD 8.17 years. There were three times as many males (4...
Kingston JK, Bayly WM, Sellon DC, Meyers KM, Wardrop KJ.To investigate the effects of formaldehyde fixation on equine platelets using flow cytometric methods to evaluate markers of platelet activation. Methods: Blood samples from 6 Thoroughbreds. Methods: The degree of fluorescence associated with binding of fluorescein isothiocyanate (FITC)-conjugated anti-human fibrinogen antibody and FITC-annexin V in unactivated and adenosine diphosphate (ADP)-, platelet activating factor (PAF)-, and A23187-activated platelet samples in unfixed and 0.5, 1.0, and 2.0% formaldehyde-fixed samples was assessed by use of flow cytometry. Results: In samples incubated...
Hollingsworth SR, Pusterla N, Kass PH, Good KL, Brault SA, Maggs DJ.To determine the role of equine herpesvirus (EHV) in idiopathic keratoconjunctivitis in horses and to determine whether sample collection method affects detection of EHV DNA by quantitative polymerase chain reaction (qPCR). Methods: Twelve horses with idiopathic keratoconjunctivitis and six horses without signs of ophthalmic disease. Methods: Conjunctival swabs, corneal scrapings, and conjunctival biopsies were collected from 18 horses: 12 clinical cases with idiopathic keratoconjunctivitis and six euthanized controls. In horses with both eyes involved, the samples were taken from the eye judg...
Pinto NI, Gilger BC.To determine the feasibility of using a handheld spectral-domain optical coherence tomography (SD-OCT) instrument to characterize normal corneal, retinal, and optic nerve head anatomy in vivo in standing horses. Methods: Clinically normal horses under sedation, palpebral nerve blockage, and pharmacologically induced mydriasis were imaged with a SD-OCT instrument (Envisu SD-OCT, Bioptigen, Inc., Morrisville, NC). Radial volumes from the cornea (axial, superior, inferior, nasal, and temporal), and rectangular volumes from the retina (dorsal, ventral, nasal, and temporal) and optic nerve head wer...
Ström L, Bröjer J, Ekesten B.Visual evoked potentials (VEPs) are electrical potentials generated by neurons in the central nervous system in response to visual stimuli. A series of positive and negative wavelets in response to flash-stimuli (flash-VEP; FVEP) or reversing, iso-luminant patterns (pattern-VEP; PVEP) are recorded. Pathological conditions affecting the post-retinal pathways can alter overall waveform morphology, and also affect wavelet peak times and amplitudes. FVEPs have recently been described in horses, but more data on the variability within and between subjects is required, to adequately interpret result...
Rushton JO, Tichy A, Nell B.To date assessment of changes in ocular temperature, as a hallmark of uveitis in horses has not been determined. Therefore the aim of the current study was to determine whether ocular temperature is increased in acute uveitic eyes compared with non-uveitic eyes, and to compare an affordable thermometry device with a thermography device. Methods: Ocular temperatures of both eyes of five horses with acute unilateral uveitis and 10 normal horses were measured using thermometry and thermography. Presence and absence of acute uveitis were diagnosed through a complete ophthalmological examination. A...
Whigham HM, Brooks DE, Andrew SE, Gelatt KN, Strubbe DT, Biros DJ.Contact neodymium:yttrium aluminum garnet (Nd:YAG) laser transscleral cyclophotocoagulation (TSCP) was performed on 23 eyes of 16 horses for treatment of glaucoma. The mean highest preoperative IOP was 51 +/- 17 mmHg. Follow-up evaluation was available for 19 eyes 1 day after surgery, 14 eyes from 1 to 2 weeks, 16 eyes from 4 to 6 weeks, 9 eyes from 12 to 16 weeks, and 10 eyes greater than 20 weeks after laser treatment. The mean intraocular pressure (IOP) the day following surgery was 34 +/- 13 mmHg. The mean IOP for each follow-up period was: one to two weeks postoperative, 23 +/- 9 mmHg; fo...
Leiva M, Peña T, Armengou L, Cesarini C, Monreal L.Septicemia in humans is described as a leading cause of uveitis, which eventually can induce blindness. Objective: Uveal inflammatory findings could be related to sepsis severity in newborn foals and might be used as an indirect indicator for survival. Methods: Seventy-four septic foals, 54 nonseptic foals, and 42 healthy foals. Methods: Prospective observational clinical study. A detailed blinded, ophthalmic examination was performed by boarded ophthalmologists on all admitted newborn foals. Foals were grouped as septic (when blood culture resulted positive or the sepsis score was > or =14...
Hermans H, Ensink JM.Distichiasis is very uncommon in horses and treatment options and outcome remain unknown. Objective: To describe treatment and long-term follow-up of distichiasis in the horse. Methods: Retrospective clinical study. Methods: Case records of horses admitted for diagnosis and treatment of uni- or bilateral distichiasis between 2003 and 2012 were reviewed. Long-term (>6 months after last treatment) follow-up was by telephone conversation with the owner or referring veterinarian. Data were analysed using a Chi-squared test. Results: Eighteen cases were identified, of which 17 were Friesians. All h...
