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.
Bradley C, Grundon R, Sansom PG.Uveitis is reported to be a leading cause of blindness in horses. Little work has been undertaken to date to investigate whether donkeys are affected by a similar disease prevalence. Objective: To investigate the disease prevalence of uveitis in a population of donkeys in the UK. Methods: Descriptive observational study. Methods: An ophthalmic examination was performed on each donkey, in a darkened stable. Each donkey underwent slit lamp biomicroscopy, and direct and/or indirect ophthalmoscopy. Fluorescein staining, STT1 and IOPs were measured when deemed clinically necessary. Pharmacologica...
Flores MM, Del Piero F, Habecker PL, Langohr IM.Ocular diseases are an important category in equine medicine; however, most articles regarding histologic ocular lesions in horses are exclusive to a specific condition and do not provide a complete review of clinically significant ocular disease frequency in a diagnostic laboratory. We reviewed sections of equine eyes from 140 cases (98 enucleations [biopsies] and 42 autopsies) with clinically relevant ocular alterations at 2 diagnostic centers in the United States. The most common primary conditions were non-traumatic keratitis (36), equine recurrent uveitis (ERU; 31), traumatic injuries (22...
Shipman E, Burford JH, Bowen M, Duz M.Teaching and learning how to perform examination of the ocular fundus is challenging. Smartphones can support to enhance students' confidence and experience. Following an optional year-4 ophthalmoscopy practical using hand-held ophthalmoscopes, students completed a questionnaire using a visual analogue scale (VAS) investigating if students felt smartphone use aided learning and if student's self-assessed confidence in visualising the ocular fundus had improved. VAS scores were compared using the Wilcoxon signed rank test (significance: P<0.05). All 30 year-4 students attending the practic...
Lewin AC, Liu CC, Camacho-Luna P, Alling C, Carter RT.It is currently unknown which of the two devices most commonly used in equine ophthalmology for intraocular pressure (IOP) estimation demonstrates the lowest inter-user and intra-user variation. Objective: To assess the inter-user and intra-user variation of two tonometers in sedated and unsedated horses. Methods: Randomised masked cross-over trial. Methods: Four examiners used the rebound (ICare TonoVet) and applanation (TonoPen ) tonometers to measure the intraocular pressure (IOP) in triplicate in 10 normal horses before and after sedation with xylazine. For inter-user variation, coefficien...
LaFrentz S, Abarca E, Mohammed HH, Cuming R, Arias CR.The equine conjunctival microbiota has often been reported to be dominated by Gram-positive species such as Staphylococcus sp., Bacillus sp., and Corynebacterium sp. However, traditional culture-based methods can only recover a fraction of the bacterial species present in the sample. Objective: This pilot study aimed at exploring the diversity of the equine conjunctival microbiota using culture-independent methods. Methods: Eight horses were included in this study, and only eyes with normal ophthalmic examination (n = 15 eyes) were sampled. Methods: Conjunctival biopsies (culture-independent...
Diehl K, Bowden AC.To assess rebound tonometry intraocular pressure (IOP) in unsedated horses without and with auriculopalpebral (AP) nerve blocks. Methods: Twenty-two client- and twenty university-owned horses (84 total eyes) with unremarkable ophthalmic examinations were evaluated. Methods: One eye of each horse was chosen randomly, an AP block performed for that eye, and IOP measured in both eyes with a TonoVet . The process was repeated for the contralateral eye 72 hours later under the same conditions as the initial measurements. Horses were unsedated for nerve blocks and tonometry. Linear mixed-effects mo...
Maharana BR, Potliya S, Ganguly A, Bisla RS, Mishra C, Ganguly I.Equine ocular setariasis arising mainly from ectopic infestation of Setaria digitata is a common vision impairing ophthalmic disease in India, and the identification of this filarial nematode is based solely on morphology. However, morphological characters alone are inadequate to detect and differentiate S. digitata from its congeners. The present communication reports the first phylogenetic characterization of equine S. digitata from India based on sequences derived from the mitochondrial cytochrome c oxidase subunit 1 (COI), the mitochondrial small subunit ribosomal DNA (12S rDNA), and the n...
Blohm KO, Tichy A, Nell B.To determine efficacy of contrast-enhanced ultrasonography (CEUS) using different sulfur hexafluoride (SF6) doses to assess blood flow and perfusion in equine eyes and to evaluate safety of SF6 in horses. Methods: Ocular B-mode and contrast-enhanced ultrasonography were performed bilaterally in nine sedated university-owned horses. Intravenous SonoVue® bolus injections of 5, 10, 15, 20, 25, and 30 mL were administered for 2/18, 5/18, 6/18, 3/18, 1/18, and 1/18 eyes, respectively. Doses were increased based on ascending bodyweight. Each eye within one horse was examined utilizing a different ...
Allnoch L, Peters M, Wiemer F, Wohlsein P.Severe bilateral mydriasis and bilaterally decreased vision were observed in a 23-year-old crossbred warmblood gelding with a history of pituitary pars intermedia dysfunction. Ten years after the onset of clinical signs, it was killed humanely because of worsening of clinical signs and loss of therapeutic responsiveness. Postmortem examination of the head was performed to confirm the suspected pituitary neoplasm and to investigate secondary oculomotor lesions. Pathomorphologic examination revealed an expansile space-occupying pituitary adenoma and degenerative changes in the preganglionic ocul...
Dennis DA, Pinard CL, Kenney DG, Salcedo RJ, Trout DR.The standard placement of a subpalpebral lavage system may not be feasible in some horses with eyelid disease. We describe placement of a commercially available, indwelling nasolacrimal lavage system that circumvents eyelid perforation. This novel approach provided for effective delivery of drugs to 1 horse with periocular and corneal disease. . Le placement standard d’un système de lavage subpalpébral peut ne pas être réalisable chez certains chevaux atteints de maladies oculaires. Nous décrivons le placement d’un système de lavage nasolacrymal à demeure qui évite la perforation d...
Gupta RC, Lall R, Srivastava A, Sinha A.Hyaluronic acid (also known as hyaluronan or hyaluronate) is naturally found in many tissues and fluids, but more abundantly in articular cartilage and synovial fluid (SF). Hyaluronic acid (HA) content varies widely in different joints and species. HA is a non-sulfated, naturally occurring non-protein glycosaminoglycan (GAG), with distinct physico-chemical properties, produced by synoviocytes, fibroblasts, and chondrocytes. HA has an important role in the biomechanics of normal SF, where it is partially responsible for lubrication and viscoelasticity of the SF. The concentration of HA and its ...
Peng TL, Armiladiana MM, Ruhil HH, Maizan M, Choong SS.The occurrence of Setaria digitata in a horse is reported for the first time in Malaysia. An 8-year-old Thoroughbred cross mare was referred to the University Veterinary Clinic with the primary complaint of corneal opacity and excessive eye discharge. After initial treatment with Terramycin eye ointment, corneal opacity cleared partially to reveal a moving thread-like cylindrical worm in the anterior chamber of the eye. The parasite was successfully removed surgically, and examination under the light microscope revealed that the isolated worm (length = 45 mm) was a 5th stage larva of S. ...
Regnier A, Martin C, Semin MO, Lienard E, Geffre A, Douet JY, Raymond-Letron I.An 18-month-old Arabian-English filly resident in southwest France was referred for evaluation of a conjunctival mass in the right eye (OD). A pink, solid, and mobile nodular formation, measuring approximately 1.2 × 0.8 cm was found under the superior nasal bulbar conjunctiva during an ophthalmic examination that was otherwise normal. The mass was surgically removed using a standing procedure. Cytological examination of fine-needle aspirates from the mass revealed a mixed eosinophilic-lymphocytic inflammation. Histological examination confirmed the dense and diffuse eosinophilic-lymphocyti...
Ledbetter EC, Irby NL.To describe the corneal in vivo confocal microscopy (IVCM) findings in horses with putative immune-mediated keratitis (IMMK). Methods: Sixty five horses with IMMK. Methods: Horses diagnosed with IMMK were examined with a modified Heidelberg Retina Tomograph II and Rostock Cornea Module. The findings from the IVCM examinations were correlated with clinical details from ophthalmic examination and diagnostic test results. Results: Eighty eyes from 65 horses were examined. Clinical IMMK lesions were categorized as epithelial (n = 17 eyes), superficial stromal (n = 38), midstromal (n = 18), a...
Scott EM, Arnold C, Dowell S, Suchodolski JS.Next generation sequencing (NGS) studies have demonstrated a rich and diverse ocular surface-associated microbiota in people that was previously undetected by traditional culture-based methods. The ocular surface microbiome of horses has yet to be investigated using NGS techniques. This study aimed to determine the bacterial composition of the ocular surface microbiome in healthy horses, and to identify whether there are microbial community changes over time and following topical antibiotic use. One eye of 12 horses was treated 3 times daily for 1 week with neomycin-polymyxin-bacitracin ophtha...
Cullen M, Jacob ME, Cornish V, VanderSchel IQ, Cotter HVT, Cubeta MA, Carbone I, Gilger BC.Morphological characterization and multi-locus DNA sequence analysis of fungal isolates obtained from 32 clinical cases of equine fungal keratitis (FK) was performed to identify species and determine associations with antifungal susceptibility, response to therapy and clinical outcome. Two species of Aspergillus (A. flavus and A. fumigatus) and three species of Fusarium (F. falciforme, F. keratoplasticum, and F. proliferatum) were the most common fungi isolated and identified from FK horses. Most (91%) equine FK Fusarium nested within the Fusarium solani species complex (FSSC) with nine geneti...
Bonsembiante F, Perazzi A, Deganello A, Gelain ME, Iacopetti I.The cytobrush technique is commonly used to sample the equine ocular surface. Impression cytology (IC) is an innovative noninvasive method, which allows for the collection of superficial layers of ocular epithelium. Objective: The aims of this study were to compare the cytobrush and IC techniques on healthy equine ocular surfaces, to assess the agreement between observers with different levels of expertise, and to test the preservability of filters over time. Methods: Twenty-four horses were sampled within 10 minutes of slaughter using IC on the left eye and the cytobrush technique on the rig...
Launois T, González Hilarión LM, Barbe F, Leurquin C, Bihin B, Hontoir F, Dugdale A, Vandeweerd JM.We report a retrospective evaluation of intravitreal gentamicin (6 mg in 0.3 mL solution) injection in 71 horses with equine recurrent uveitis between 2010 and 2016. Aqueous flare and hyalitis were scored at the baseline in all horses, then at 15, 30, 60, 90, 180, 365, and 730 in 37, 46, 30, 25, 22, 18, and 11 horses, respectively. Forty-two animals had a global score of inflammation (sum of scores for aqueous flare and hyalitis) of zero at the last examination (number of re-examinations per horse ranged from 1 to 5). Among the 29 remaining horses, four were not reassessed after the interven...
Berkowski W, Plummer CE, Ramos R, Czerwinski S, Brooks D, Gallagher A.A yearling Thoroughbred stallion and an 8-year-old Saddlebred mare were evaluated for persistent mucoid ocular discharge. Results: Examination of both horses revealed copious yellow-tan mucoid ocular discharge with a negative Jones I test, absent nasal punctum, and unsuccessful anterograde nasolacrimal duct (NLD) irrigation. Clinical abnormalities were present on the right side only in one horse and bilaterally in the other. Computed tomography (CT) with contrast confirmed nasolacrimal duct atresia in both horses. Results: Under general anesthesia, the affected NLD was catheterized anterograde...
Blanchard A, Barr EM, Gilger BC.The purpose of this case series is to evaluate the use of spectral domain optical coherence tomography (SD-OCT) imaging in equine corneal disease to demonstrate the feasibility, diagnostic effectiveness, and limitations of this imaging modality. Methods: Retrospective study: Handheld SD-OCT (Envisu, Bioptigen Inc, Morrisville, NC) was used for high-resolution imaging of horses with corneal disease presenting to the North Carolina State University Equine Ophthalmology Service from 2013 to 2018. Results: Fourteen horses were included in this study, including six horses with corneal ulceration, t...
Hollis AR, Dixon JJ, Berlato D, Murray R, Weller R.There are limited data on whether the dimensions of the equine eye and its internal structures change with bodyweight in horses. The aim of this study was to identify whether the size of the equine eye and its individual structures varied in a predictable manner with bodyweight, and to examine the reliability of computed tomography (CT) scans in the measurement of the equine eye. Ninety horses which had undergone CT examination of the head for non-ocular disease were included. All measurements of the eye were performed twice on all eyes by the same operator to quantify intra-operator agreement...
Davis AB, Schnabel LV, Gilger BC.Equine immune-mediated keratitis (IMMK) leads to increased corneal opacity and inflammation secondary to an alteration of the local immune system. Bone marrow-derived mesenchymal stem cells (BM-MSC) have been shown to modulate the immune system by downregulating inflammation. Four horses with unilateral IMMK poorly responsive to traditional medical treatments underwent novel, autologous subconjunctival BM-MSC therapy. Bone marrow was harvested and processed as previously described for equine orthopedic disease. Horses received autologous subconjunctival BM-MSC injections approximately every 3-...
Tarancón I, Leiva M, Jose-Cunilleras E, Ríos J, Peña T.To describe ocular findings associated with Rhodococcus equi bronchopneumonia in foals, and to determine whether severity of the ocular lesions is related with outcome. Methods: Foals diagnosed with R equi infection at the VTH-UAB from January 2002 to December 2017. Methods: Rhodococcus equi infection was diagnosed by means of clinical signs, radiographic/ultrasonographic findings, and/or positive culture. In all the foals, a complete ophthalmic examination by a boarded ophthalmologist was performed and ocular signs were recorded and graded (0-4). Results: Thirty-nine foals were included in t...
Ansari Mood M, Rajaei SM, Faghihi H, Ghiadi A.This study was performed to evaluate the effect of topical 1% cyclopentolate hydrochloride on tear production (STT), intraocular pressure (IOP), and vertical pupil diameter (VPD) in healthy Turkman horses. Forty eyes of 20 clinically normal horses were used for this study, which were randomly assigned to two groups. Before instillation of 1% cyclopentolate, the baseline STT, IOP, and VPD of each group were recorded. Then, one drop of cyclopentolate was instilled randomly into one eye of each animal, and the contralateral eye served as control. Measurements were repeated at 20 minutes, 60 min...
Steinmetz A, Gittel C, Böttcher D, Lapko L, Offhaus J.A melanoma of the upper eyelid was resected in a gray warmblood gelding. A full functional eyelid could be obtained by completion a sliding skin graft with a free labial mucocutaneous graft transplantation to restore the mucocutaneous junction and to decrease the risk of postoperative trichiasis.
Andrysikova R, Pot S, Rüegg S, Markova J, Horackova E, Kolos F, Voelter K, Spiess B.To screen a closed herd of the Old Kladruber Horses (OKH) for the prevalence of ocular disorders and report normal ocular variations. Methods: Two hundred and sixty-one horses, 122 Old Kladruber Gray Horses, and 139 Old Kladruber Black Horses owned by the National Stud Farm Kladruby nad Labem, Czech Republic, were included in the study with signalment and pedigree information recorded. Methods: Bilateral ocular examination of manually restrained horses was performed in a darkened environment by a single examiner (RA), using a portable slit-lamp biomicroscope, direct ophthalmoscope, and monocul...
Sauvage AC, Monclin SJ, Elansary M, Hansen P, Grauwels MF.Equine recurrent uveitis (ERU) has been associated with Leptospira spp. infection. No information exists concerning the prevalence of Leptospira-associated ERU in Belgium and about the sensitivity of detection of Leptospira in different ocular media. Objective: To establish the prevalence of intraocular Leptospira spp. in ERU-affected and healthy eyes of horses examined at the Equine Clinic of the University of Liège by real-time PCR and to compare the results of the aqueous and vitreous humour of the same eye. Methods: Cross-sectional. Methods: Sixty-six eyes from 59 client-owned horses with...
Knickelbein KE, Lassaline ME, Bellone RR.To document a case of limbal squamous cell carcinoma (SCC) in a Rocky Mountain Horse stallion determined to be homozygous for the genetic risk factor (DDB2 c.1013C>T) strongly associated with the disease in Haflinger and Belgian horses, and to determine the frequency of this allele in a larger population of Rocky Mountain Horses. Methods: One privately owned Rocky Mountain Horse and 84 Rocky Mountain Horses screened for allelic frequency. Methods: A complete ophthalmic examination was performed on a Rocky Mountain Horse stallion for assessment of a mass affecting the right eye. A clinical diag...
Gialletti R, Marchegiani A, Valeriani T, Nannarone S, Beccati F, Fruganti A, Laus F.To describe the association of clinical and ultrasonographic (US) findings in horses affected by visual impairments, to estimate the most frequent ultrasonographic alteration as well importance and limits of US as a part of ophthalmic evaluation in equine patients. Methods: One-hundred-forty-five horses referred to the Veterinary Teaching Hospitals of the University of Perugia and Camerino for ocular problems were submitted to ophthalmic examination and ocular ultrasound. The following group of abnormalities was established: corneal alteration, cataract, synechiae, iris prolapse, anterior cham...
Boveland SD, Moore PA, Mysore J, Krunkosky TM, Dietrich UM, Jarrett C, Paige Carmichael K.Determine the effects of matrix metalloproteinases (MMPs)-2, -9, macrophage inflammatory protein-2 (MIP-2), tissue inhibitors of matrix metalloproteinase (TIMP)-1 and -2 by immunohistochemical expression in fungal affected and purulonecrotic corneas. Methods: Paraffin-embedded equine corneal samples; normal (n = 9), fungal affected (FA; n = 26), and purulonecrotic without fungi (PN; n = 41) were evaluated immunohistochemically for MMP-2, -9, MIP-2, TIMP-1 and -2. The number of immunoreactive inflammatory cells was counted and statistics analyzed. Western blot was performed to detect MMP-2, MMP...
Ségard EM, Depecker MC, Lang J, Gemperli A, Cadoré JL.(1) To describe the ultrasonographic appearance of multiple congenital ocular anomalies (MCOA) in the eyes of horses with the PMEL17 (Silver) mutant gene. (2) To compare the accuracy of B-mode ocular ultrasound to conventional direct ophthalmoscopy. Methods: Sixty-seven Comtois and 18 Rocky Mountain horses were included in the study. Methods: Horses were classified as being carriers or noncarriers of the PMEL17 mutant allele based on coat color or genetic testing. Direct ophthalmoscopy followed by standardized ultrasonographic examination was performed in all horses. Results: Seventy-five of 8...
Scantlebury CE, Aklilu N, Reed K, Knottenbelt DC, Gebreab F, Pinchbeck GL.Ocular disease is a frequent finding in working horses. This study aimed to estimate the prevalence and types of ocular pathology, and explore risk factors potentially associated with disease within a population of working horses in Ethiopia. In total, 1049 horses were selected from horses attending clinics run by the Society for Protection of Animals Abroad (SPANA). Each had an ophthalmic examination conducted under field conditions using a pen-torch. All owners completed a short questionnaire. The prevalence of ocular abnormalities was 23.5 per cent (95 per cent confidence interval (CI) 18.0...
Beckwith-Cohen B, Elad D, Bdolah-Abram T, Ofri R.To determine baseline tear pH in dogs, horses, and cattle by use of a microelectrode. Methods: 28 dogs, 24 horses, and 29 cattle. Methods: Under manual restraint, tears were collected from each subject's left eye with cotton spears. A Schirmer tear test was performed in the right eye. Tears were extracted from the spears by centrifugation. Tear volume was measured, pH was determined with a microelectrode, and total solids (TS) concentration was measured by refractometry. Results: Mean ± SD pH of tears in cattle, dogs, and horses was 8.32 ± 0.14, 8.05 ± 0.26, and 7.84 ± 0.30, respectively. ...
Scherrer NM, Lassaline M, Engiles J.To determine the characteristics of and prognosis for ocular and periocular hemangiosarcoma in horses. Methods: Six horses treated for ocular or periocular hemangiosarcoma. Methods: A retrospective review of medical records from 2007 to 2015 was performed to identify horses with a histologic diagnosis of ocular or periocular hemangiosarcoma. Signalment (age, sex, breed), duration of clinical signs, prior treatment, tumor size and location, medical and surgical treatment including postoperative chemotherapy, follow-up time, and outcome were obtained from medical records. Histopathology was revi...
Brooks DE, Plummer CE, Kallberg ME, Barrie KP, Ollivier FJ, Hendrix DV, Baker A, Scotty NC, Utter ME, Blackwood SE, Nunnery CM, Ben-Shlomo G....To evaluate the visual outcome of three techniques of corneal transplantation surgery in treating severe inflammatory keratopathies in the horse. Methods: Retrospective medical records study. Methods: Medical records of 206 horses that received corneal transplantation surgery at the University of Florida Veterinary Medical Center from 1993 to 2007 were reviewed. Methods: Data collected from the medical records included signalment, types of ocular lesions, type of transplant surgery performed, length of follow-up, complications, and visual outcomes. Results: Full thickness penetrating keratopla...
Padjasek M, Qasem B, Cisło-Pakuluk A, Marycz K.Cyclosporine A (CsA) is a selective and reversible immunosuppressant agent that is widely used as a medication for a wide spectrum of diseases in humans such as graft versus host disease, non-infectious uveitis, rheumatoid arthritis, psoriasis, and atopic dermatitis. Furthermore, the CsA is used to treat keratoconjunctivitis sicca, chronic superficial keratitis, immune-mediated keratitis and equine recurrent uveitis in animals. The selective activity of Cyclosporine A (CsA) was demonstrated to be an immunomodulation characteristic of T-lymphocyte proliferation and inhibits cytokine gene expres...
Scotty NC, Cutler TJ, Brooks DE, Ferrell E.To define the indications for equine ocular ultrasonography and to provide representative ultrasonographic images of lens and posterior segment diseases. Methods: Retrospective study. Equine medical records dating from January 1983 to March 2001 were reviewed. All cases that: (1) had a lens and/or posterior segment abnormality; and (2) received a complete ophthalmic examination and ocular ultrasonography were included. Results: Forty-three cases (n = 64 eyes) out of 112 total cases of equine lens and/or posterior segment abnormalities qualified. The following conditions were identified ultraso...
Mancuso LA, Lassaline M, Scherrer NM.To describe the clinical course, outcomes, and complications associated with use of commercially available porcine urinary bladder extracellular matrix (ECM) grafts (ACell Vet(®) Corneal Discs) in equid patients with keratomalacia, and to evaluate the efficacy of ECM grafts as a viable alternative to other biomaterials for corneal grafting in equid patients. Methods: Sixteen horses and one donkey (17 eyes) with unilateral keratomalacia severe enough to warrant surgical repair between August 2012 and September 2013. Methods: Retrospective medical record review to identify equid patients meetin...
Mustikka MP, Pietilä EM, Mykkänen AK, Grönthal TSC.To obtain a reference range for evaluation of intraocular pressure (IOP) in horses using Tonovet Plus , to compare the IOP readings obtained with Tonovet and Tonovet Plus , and to evaluate the repeatability of readings. Unassigned: Intraocular pressure of 30 client-owned horses (60 eyes) with no signs of illness or ocular disease was evaluated using Tonovet and Tonovet Plus rebound tonometers. Horses' mean age was 10.7 (range 6-17) years. Triplicate measurements were performed without using sedatives or local anesthetics, with minimal restraint. Results: Calculated reference intervals (the CLS...
Khosravi AR, Nikaein D, Sharifzadeh A, Gharagozlou F.This study was carried out in order to isolate and identify the normal conjunctival fungal flora from Caspian miniature, Thoroughbred, Turkmen and Persian Arab breeds in Tehran, Iran. Methods: A total of seventy-two adult healthy horses were studied. Ocular samples were collected from right and left eyes by using sterile cotton swabs; samples were cultured on Sabouraud dextrose agar and incubated at 30°C for 7-10 days. Molds and yeasts were identified using macro and micro-morphological and physiological characteristics. Conclusions: Number of fungal colonies per eye varied between 0 and 123 ...
Knickelbein KE, Lassaline ME, Bellone RR.To document a case of limbal squamous cell carcinoma (SCC) in a Rocky Mountain Horse stallion determined to be homozygous for the genetic risk factor (DDB2 c.1013C>T) strongly associated with the disease in Haflinger and Belgian horses, and to determine the frequency of this allele in a larger population of Rocky Mountain Horses. Methods: One privately owned Rocky Mountain Horse and 84 Rocky Mountain Horses screened for allelic frequency. Methods: A complete ophthalmic examination was performed on a Rocky Mountain Horse stallion for assessment of a mass affecting the right eye. A clinical diag...
Dziezyc J, Millichamp NJ, Smith WB.Two Mackay-Marg tonometers and 2 Tono-Pen tonometers were evaluated in eyes in which intraocular pressure (IOP) had been altered and measured by use of a manometer. Eyes of anesthetized dogs and enucleated horse eyes were used. Compared with the manometer, none of the tonometers accurately measured IOP over the range between 0 and 100 mm of Hg. However at manometer measurements from 0 to 30 mm of Hg, several of the tonometers accurately measured IOP. In addition, significant differences were observed when the measurement accuracy of one tonometer was compared with that of another, especially a...
Rohrbach BW, Ward DA, Hendrix DV, Cawrse-Foss M, Moyers TD.To evaluate the effect of vaccination against leptospirosis on frequency and days to recurrence of uveitis and progression of disease in horses with equine recurrent uveitis (ERU). Methods: Forty-one horses with ERU. Methods: Horses were randomly assigned to experimental (vaccinated) or control groups. Vaccine containing six serovars of Leptospira or placebo was administered, an ophthalmic examination performed and blood samples drawn on days 0, 28, 180 and 365. Antibody titers were measured against each serovar. Recurrence of uveitis was verified by ophthalmic examination. Results of the init...
Brem S, Gerhards H, Wollanke B, Meyer P, Kopp H.Vitreous samples from 43 horses which underwent vitrectomy because of equine recurrent uveitis (ERU) were cultured for leptospires. Out of 4 vitreous samples (4/43 = 9%), leptospires could be isolated. In 3 cases, serovar grippotyphosa, and in one case, a serovar out of the serogroup Australis were identified. So for the first time, in several horses with ERU in vivo cultures of vitreous material were positive for leptospires. A strong evidence of association between leptospiral infection and uveitis is discussed for many years. In this investigation the leptospiral etiology is confirmed. Vitr...
Badial PR, Cisneros-Àlvarez LE, Brandão CV, Ranzani JJ, Tomaz MA, Machado VM, Borges AS.The aim of this study was to compare ocular dimensions, corneal curvature, and corneal thickness between horses affected with hereditary equine regional dermal asthenia (HERDA) and unaffected horses. Methods: Five HERDA-affected quarter horses and five healthy control quarter horses were used. Methods: Schirmer's tear test, tonometry, and corneal diameter measurements were performed in both eyes of all horses prior to ophthalmologic examinations. Ultrasonic pachymetry was performed to measure the central, temporal, nasal, dorsal, and ventral corneal thicknesses in all horses. B-mode ultrasound...
Zeiss C, Neaderland M, Yang FC, Terwilliger G, Compton S.To assess the diagnostic utility of fungal polymerase chain reaction (PCR) in forty-three horses with naturally acquired corneal ulcers presenting to a private practice. Methods: Routine evaluation of cytologic, histologic, and microbiologic samples was performed. Two PCR approaches were compared - generic and specific fungal nested PCR followed by sequencing and quantitative PCR (qPCR). PCRs were applied to pure control fungal cultures, corneal tissue from ulcerated eyes and in a subset of 9 horses, to swabs from contralateral normal eyes. Results: The expected fungus was identified by nested...
Sullins KE, Stashak TS, Mero KN.In 6 horses, 2 types of ischemic lesions were created in small intestinal segments by selective ligation of vessels and intestinal wall for 1, 2, or 3 hours. After confirming the ischemia by IV injection of sodium fluorescein, the ligatures were released. Five minutes later, the fluorescent patterns were documented photographically. Observed patterns ranged from normal (identical to that observed in unaffected bowel) to a patchy distribution of non-fluorescence (indicating incomplete perfusion). None of the experimental segments was normal when reevaluated 1 month later. The typical appearance...
Williams LB, Pinard CL.Corneal ulceration is commonly diagnosed by equine veterinarians. A complete ophthalmic examination as well as fluorescein staining, corneal cytology, and corneal bacterial (aerobic) and fungal culture and sensitivity testing are necessary for all infected corneal ulcers. Appropriate topical antibiotics, topical atropine, and systemic NSAIDs are indicated for all corneal ulcers. If keratomalacia (melting) is observed, anticollagenase/antiprotease therapy, such as autologous serum, is indicated. If fungal infection is suspected, antifungal therapy is a necessity. Subpalpebral lavage systems all...
Barsotti G, Sgorbini M, Marmorini P, Corazza M.To determine the prevalence and describe ocular abnormalities in healthy Standardbred foals within 48 h of birth. Methods: One hundred and two neonatal foals. Methods: All foals had an unassisted delivery. On the basis of physical examination and the results of hematological and biochemical parameters, all foals were unaffected by systemic diseases. A complete ophthalmic examination was performed within 48 h of birth. Foals with ocular hemorrhages were re-examined weekly until the abnormalities were resolved. Results: 65/102 (63.7%) foals did not show ocular abnormalities, while in 37/102 (36....
Cheng FP, Gadella BM, Voorhout WF, Fazeli A, Bevers MM, Colenbrander B.The aim of the present study was to investigate whether the induction of stallion sperm acrosome reaction (AR) by progesterone is mediated by binding of progesterone to a receptor on the sperm plasma membrane or to an intracellular progesterone receptor. Progesterone-BSA conjugate labeled with fluorescein isothiocyanate (P-BSA-FITC) in combination with a vital stain, ethidium homodimer, was applied to visualize the presence of the progesterone receptor on living spermatozoa. Alternatively, an indirect immunofluorescence technique employing a monoclonal antibody (C-262) against human intracellu...
Martin de Bustamante M, Gomez D, MacNicol J, Hamor R, Plummer C.The objective of this study was to describe and compare the fecal bacterial microbiota of horses with equine recurrent uveitis (ERU) and healthy horses using next-generation sequencing techniques. Fecal samples were collected from 15 client-owned horses previously diagnosed with ERU on complete ophthalmic examination. For each fecal sample obtained from a horse with ERU, a sample was collected from an environmentally matched healthy control with no evidence of ocular disease. The Illumina MiSeq sequencer was used for high-throughput sequencing of the V4 region of the 16S rRNA gene. The relativ...
Kalf KL, Utter ME, Wotman KL.To measure duration of corneal anesthesia and time and degree of maximal anesthetic effect of 0.5% proparacaine hydrochloride by use of a Cochet-Bonnet aesthesiometer in horses. Methods: 10 clinically normal adult horses. Methods: Baseline corneal touch threshold (CTT) was measured in millimeters for 1 randomly selected eye of each horse by use of the aesthesiometer by applying the filament to the cornea at maximum length (60 mm) and decreasing in 5-mm increments until a consistent blink response was elicited. Following baseline CTT measurement, 0.2 mL of 0.5% proparacaine hydrochloride was in...
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.
Yi NY, Davis JL, Salmon JH, Gilger BC.To determine ocular distribution and toxicity of a single injection of intravitreal triamcinolone acetonide (TA) in normal horses. Methods: Six adult horses, donated to North Carolina State University. Methods: Six horses were injected intravitreally with either 10, 20, or 40 mg (n = 2 each) of TA. The opposite eye of each horse was injected with balanced salt solution (BSS). Ocular toxicity was assessed by biomicroscopy, tonometry, indirect ophthalmoscopy, and electroretinogram. Aqueous humor (AH), vitreous humor (VH), and plasma samples were collected. Horses were euthanized 7 or 21 days aft...
The Journal of physiologyOctober 24, 2003
Volume 554, Issue Pt 3 791-801 doi: 10.1113/jphysiol.2003.054809
Kostyuk O, Birch HL, Mudera V, Brown RA.This study aimed to investigate the preferential collagen fibril alignment in unloaded and loaded tendons using elastic scattering spectroscopy. The device consisted of an optical probe, a pulsed light source (320-860 nm), a spectrometer and a PC. Two probes with either 2.75 mm or 300 microm source-detector separations were used to monitor deep and superficial layers, respectively. Equine superficial digital flexor tendons were subjected to ex vivo progressive tensional loading. Seven times more backscattered light was detected parallel rather than perpendicular to the tendon axis with the 2.7...
Herring IP, Pickett JP, Champagne ES, Troy GC, Marini M.OBJECTIVE: To determine the effect of topical 1% ophthalmic atropine sulfate on intraocular pressure (IOP) in ocular normotensive horses. Animals Studied Eleven clinically healthy horses. Procedures IOP was measured bilaterally twice daily, at 8 AM and 4 PM, for 5 days. No medication was applied for the first 2 days of the study. Thereafter, one eye of each horse was treated with 0.1 mL of topical 1% atropine sulfate ointment twice daily (7 AM and 7 PM) for 3 days. The contralateral eye served as a control. In eight of the horses, an additional IOP reading was taken 3 days following cessation ...
