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.
Hines MT.The continued study of immunology and its relationship to diseases of the eye will hopefully give some insight into the pathogenic mechanisms of certain ocular diseases of many species, including the horse. It may lead to a better understanding of equine recurrent uveitis, a disease that has remained an enigma for years and that now appears to be an immunologic hypersensitivity response to a number of varied antigens. The precise mechanism of the inflammation is still unclear, and the immunologic response may be variable or mixed depending upon the inciting antigen. Other ophthalmic diseases i...
Glaze MB, McGuire TC, Schmidt GM, Leid RW.A quantitative investigation of equine tear and aqueous humor immunoglobulins was done using normal horses and ponies as well as horses and ponies infected with Onchocerca cervicalis. The equine immunoglobulin isotypes IgGa, IgM, IgA and IgG(T) were quantitated by either single radial immunodiffusion (SRID) or radioimmunoassay (RIA). Tear immunoglobulin levels for IgGa (128 +/- 151 micrograms/ml), IgA (1,664 +/- 1,038 micrograms/ml) and IgM (106 +/- 74 micrograms/ml) were measured, while IgG(T) was not detectable. In horses with ocular inflammation the IgGa was 18-fold higher in the tears, 2,2...
Cooley PL, Milvae R, Riis RC, Laratta LJ.A study was performed to identify prostacyclin (PGI2) in equine aqueous humor, demonstrate an increase in PGI2 following anterior chamber paracentesis, and determine the effects of subconjunctival injection of flunixin meglumine on PGI2 accumulation. Twenty ponies were found to be normal upon ocular examination and were placed under general anesthesia. Anterior chamber paracentesis was performed in both eyes (right and left); immediately afterward, 25 mg of flunixin meglumine was injected (subconjunctivally) in the left eye. Aqueous paracentesis was performed 1.5 hours later (both eyes). Aqueo...
Beech J, Aguirre G, Gross S.Nuclear cataracts were found in 2 groups of related Morgan horses. The cataracts were finely reticulated central spherical translucencies that sometimes extended to the region of the posterior "Y" suture. The cataracts were not associated with other ocular defects and did not impair vision. In 1 group of 8 horses, 5 were affected; in the other group, 6 of 8 were affected. Although a pattern of inheritance could not be determined, the familial distribution of the cataracts supported the conclusion that the defect was a heritable disorder.
Lavach JD, Severin GA, Roberts SM.Perforating corneal wounds in horses have a better prognosis than wounds that involve both cornea and sclera. Sharp objects tend to produce more isolated corneal wounds and have a better prognosis than do wounds produced by blunt objects. The records of 43 horses that sustained penetrating wounds of the cornea were reviewed. In addition, the surgical approach and postoperative wound management is described. The report attempts to provide more information regarding the management of ocular trauma in horses.
Samuelson DA, Andresen TL, Gwin RM.Conjunctival swab specimens were obtained from both eyes of 43 horses, 25 cows, 50 dogs, and 25 cats without keratitis or other ophthalmologic problems. Fungi were isolated from 95% of the horses, 100% of the cows, 22% of the dogs, and 40% of the cats. Aspergillus spp were isolated from 56% of the horses, 12% of the cows, 8% of the cats, and none of the dogs. Penicillium spp and Cladosporium spp were isolated ubiquitously. Collectively, 28 species from 209 isolants were identified.
Marolt J, Naglić T, Hajsig D.A case of a spontaneous mycokeratitis of a previously injured cornea in a horse is described. The infection was caused by Aspergillus oryzae. After application of Chloramphenicol ophthalmic ointment a corneal clouding was found in the centre which was circularly sharply defined and which - after dispensing Dexamethason-Neomycin eye drops - expanded all over to a purulent keratitis. The demarcated and initially non purulent mycotic lesions largely improved after the application of tincture of iodine, whereas the purulent keratitis could be completely cured only by a lasting treatment with Lugol...
Alter GM.In an effort to assess the influence that crystallization may have on protein conformations, optical absorption spectra of crystalline state hemoglobin derivatives have been examined. These spectra were obtained from photoacoustic spectra using a computer-assisted analysis. Comparisons of crystal and solution state hemoglobins using crystal minus solution state difference spectra indicate that the conformations of these proteins are similar in both states. Crystallization does not change the absorption properties of horse oxyhemoglobin or the cyanide and azide adducts of horse and human methem...
Floyd K, Suter PF, Lutz H.Direct staining of the granules of blood eosinophils by anti-immunoglobulin fluorescein isothiocyanate (FITC) conjugates was observed when feline blood smears were tested for presence of feline leukemia virus (FeLV) antigen by immunofluorescent antibody. When blood smears of other species including swine, horses, cattle, dogs, sheep, birds, and human beings were examined, direct staining of eosinophils by FITC conjugates was also detected. This FITC staining was restricted to eosinophils and was not observed in neutrophils, lymphocytes, and platelets. Direct FITC staining of eosinophils does n...
McLaughlin SA, Brightman AH, Helper LC, Manning JP, Tomes JE.In 123 cases of external ocular disease in the horse, pathogenic microorganisms isolated with greatest frequency were Streptococcus sp (43.9%), Staphylococcus sp (24.2%), and Pseudomonas sp (13.8%). Fungi were isolated in 4.8% of the cases. In vitro testing showed that most of the Streptococcus sp isolants were sensitive to ampicillin, cephalothin, and carbenicillin. Most of the Staphylococcus sp isolants were sensitive to gentamicin, cephalothin, and bacitracin. Most of the Pseudomonas sp isolants were sensitive to polymyxin B and gentamicin.
Neumann SM, Kainer RA, Severin GA.In the main study, hyperthermia was induced by radio-frequency current to obtain a single, central, corneal lesion in the right eye and 2 separate limbal lesions in the left eye of 13 light horses and 8 ponies. Intracorneal and intralimbal temperature profiles for the procedure were obtained in a separate study from the eyes of a horse and a pony treated in the same manner. After treatment of the principal eyes and 6 sham-treated eyes, clinical observations were conducted for up to 6 months, using indirect ophthalmoscopy, biomicroscopy, and fluorescein staining. Immediately after hyperthermic ...
Rebhun WC, Mirro EJ, Georgi ME, Kern TJ.Habronemic blepharoconjunctivitis was characterized clinically by raised yellow gritty plaques in the palpebral and bulbar conjunctivae. Lid granulomas and blepharitis were observed in some cases. On histologic examination, mast cells, eosinophils, and collagenolysis was found in most sections, but if only one section was examined an erroneous diagnosis of mastocytosis could have been made. Treatment consisted of larvicidal mixtures for lid lesions and organophosphate ophthalmic drops along with corticosteroids for the conjunctivitis. If the cornea was damaged by the gritty conjunctival plaque...
Holmberg DL.Four horses with corneal perforations of various etiologies were presented for surgical correction. Pedicle grafts taken from the bulbar or palpebral conjunctiva were used to repair the defects. Two horses regained functional vision in the affected eyes while a third had significant impairment. The fourth eye, which had an intense uveitis pre and postoperative, became phthisic and blind.
Bistner SI, Riis RC.Several manifestations of equine corenal ulcers caused by mycotic agents are discussed. Antifungal therapy is reviewed. Mycotic keratitis should be suspected when routine corneal ulcer therapy is nonproductive.
Murphy J, Young S.Sudden unilateral blindness occurred in a 7-year-old grey gelding Quarterhorse. Ophthalmoscopy revealed a pigmented mass arising from the nasal ciliary body of the right eye and extending around the posterior surface of the lens, and there were pigmented particles in the vitreous. Examination of the enucleated globe showed a circumscribed, black, dense and symmetrically ovoid mass with sessile attachment to the nasal ciliary region and extension to posterior lens capsule, vitreous and along the vitreal face of the detached retina to the optic papilla. The mass was composed of heavily pigmented...
Hefner EM, Lin HC, Cole RC, Moore PA, McMullen RJ.To compare image quality and acquisition time of corneal and retinal spectral domain optical coherence tomography (SD-OCT) under 3 different sedation-anesthesia conditions in horses. Methods: 6 middle-aged geldings free of ocular disease. Methods: 1 randomly selected eye of each horse was evaluated via SD-OCT under the following 3 conditions: standing sedation without retrobulbar anesthetic block (RB), standing sedation with RB, and general anesthesia with RB. Five regions of interest were evaluated in the cornea (axial and 12, 3, 6, and 9 o'clock positions) and fundus (optic nerve head). Thre...
Glaze MB, McGuire TC, Schmidt GM, Leid RW.A quantitative investigation of equine tear and aqueous humor immunoglobulins was done using normal horses and ponies as well as horses and ponies infected with Onchocerca cervicalis. The equine immunoglobulin isotypes IgGa, IgM, IgA and IgG(T) were quantitated by either single radial immunodiffusion (SRID) or radioimmunoassay (RIA). Tear immunoglobulin levels for IgGa (128 +/- 151 micrograms/ml), IgA (1,664 +/- 1,038 micrograms/ml) and IgM (106 +/- 74 micrograms/ml) were measured, while IgG(T) was not detectable. In horses with ocular inflammation the IgGa was 18-fold higher in the tears, 2,2...
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...
Lavach D.Performance and pleasure horses depend upon their ability to see and assess the environment. Thus, the veterinarian must be able to examine the eyes and recognize abnormalities so that the owner or purchaser can be informed about the visual status and prognosis for the horse's vision. If the veterinarian encounters suspicious or abnormal findings during the examination, a more detailed examination and/or referral to a veterinary ophthalmologist can be recommended to the owner or purchaser.
Vercruysse E, Naranjo C, Sauvage A, Vandersmissen M, Grauwels M, Monclin S.To describe the clinical, diagnostic imaging, and histopathological findings of two visually impaired closely related horses and to identify a possible cause. Methods: Two warmblood horses, with a common dam and sire, were presented to the ophthalmology department of Liège for investigation of impaired vision. Information collected included physical and ophthalmic examination findings, results of ocular ultrasound, electroretinogram, magnetic resonance imaging (MRI), and histopathology. Ophthalmic examination, ocular ultrasound and MRI revealed a complete retinal detachment (RD) in the left e...
Ortillés Á, Sanmartí J, Ríos J, Armengou L, Peña MT, Leiva M.To evaluate the effect of topical cyclopentolate hydrochloride (CH) on quantitative pupillometric readings (PR), tear production (TP), and intraocular pressure (IOP) in healthy horses. Methods: Fourteen client-owned horses. Methods: In a two-phase design study, each animal received 1% CH ophthalmic solution in the left eye [treated] and 0.9% NaCl in the right eye [control] (0.2 mL each). In the first phase (n = 7), TP, IOP, and PR assessment was performed by Schirmer tear test I, rebound tonometry and static pupillometry, at 1, 8, 24, 48, 72, 96, 120, 148, 172, and 196-hours post-instillati...
Finno CJ, Aleman M, Ofri R, Hollingsworth SR, Madigan JE, Winfield L, Bannasch DL.Neuroaxonal dystrophy (NAD) is a disease characterized by the sudden onset of neurologic signs in horses ranging from 4 to 36 months of age. Equine degenerative myeloencephalopathy (EDM), a disease that has been associated with low vitamin E concentrations, is considered a more advanced form of NAD. The objective of this report is to describe the electrophysiological features of NAD/EDM in American Quarter horses (QHs). HORSES: Six NAD/EDM-affected QHs and six unaffected QHs were evaluated by ophthalmic examination and electroretinography. Five of the NAD/EDM-affected QH and five unaffected QH...
Myrna KE, Herring IP.To assess the efficacy and kinetics of a continuous infusion modality for topical ophthalmic drug delivery via subpalpebral lavage in horses. Methods: Five ophthalmically normal horses Methods: A constant-rate continuous delivery pump was used to apply 0.01% fluorescein solution to the eyes of five ophthalmically normal horses via subpalpebral lavage. Fluorescein was applied at a rate of 0.14 mL/h for 72 h. Tear samples were collected from the ventral conjunctival fornix at regular intervals via capillary tube and tear fluorescein concentrations were determined via spectral assay. Laboratory s...
CRAWFORD M.This disease has a very long history, with the earliest written description by Vegetius in the fourth century A.D. It has many names, such as periodic ophthalmia, recurrent ophthalmia, iridocyclitis, uveitis, moon-blindness, etc. Periodic ophthalmia is perhaps the name more generally used, but I prefer to use recurrent iridocyclitis because (a) there is no definite fixed period between the recurrent attacks and (b) because the essential lesion is iridocyclitis.
Sandmeyer LS, Panizzi L, Grahn BH.The research article deals with a case study of an 18-year old male horse suffering from an enlarging mass on its right lower eyelid, which was examined and diagnosed at […]
Atai T, Ozmaie S, Anoushepour A.This research was performed to compare the effects of prednisolone and fluorometholone on intraocular pressure (IOP) and Schirmer tear test (STT) in the normal equine eye. Sixteen normal mares aged between 6 and 10 years were used for this study. Horses were randomly assigned to two groups. Eight horses in the first group received 0.2 mL of topical 1% prednisolone in one eye and the contralateral eye was used as control (0.2 mL of saline was instilled). The second group received 0.2 mL of 0.1% fluorometholone in a randomly selected eye and the contralateral eye served as control and received 0...
Knickelbein KE, Lassaline ME.Immune-mediated ocular inflammation is a common clinical diagnosis reached for horses with keratitis and uveitis. This diagnosis is made as a diagnosis of exclusion following a thorough effort to rule out an underlying cause for the inflammation, most importantly infectious and neoplastic disease. Practically, response to ophthalmic and systemic anti-inflammatory or immunomodulatory medications is used to support a diagnosis of immune-mediated ocular inflammation; however, such medications are often contraindicated in the face of infection or neoplasia. This article will summarize our current ...
D'Agostino AL, Giuliano EA, Kuroki K, Martin LM.To describe the first report of third eyelid cartilage eversion in an adult American Quarter Horse mare. Methods: A 22-year-old American Quarter Horse mare presented to the University of Missouri Veterinary Health Center Equine Hospital for a 2-week history of a third eyelid cartilage abnormality of the left eye with no known recent trauma. Complete ophthalmic examination revealed third eyelid cartilage eversion of the left nictitans. The abnormal scrolled cartilage was surgically excised using a handheld cautery unit and submitted for histopathologic evaluation. Results: Histopathologic findi...
Morgan J, Curtis Shaw G, Weisman J, Cecere T, Carvallo-Chaigneau FR.A 2-d-old Warmblood colt was submitted for autopsy with a spectrum of bilateral ocular abnormalities. At postmortem examination, a constellation of lesions within the anterior segment included retention of ectodermal elements, compatible with choristoma. Ocular choristomas can be localized to different intraocular structures and are rare in equids. The morphologic features in our case were suggestive of abnormal corneal differentiation.
Nout-Lomas YS, Story MR.Equine head and neck disorders can present with a wide range of clinical manifestations, depending on the structures involved and disease process. Important components of the gastrointestinal, respiratory, ophthalmological, neurological, and musculoskeletal systems are contained within the head and neck, and clinical signs of disorders will result in expected clinical signs. However, clinical manifestations of disease are sometimes subtle, and when not recognized can lead to behavioral changes including undesired behaviors and poor sleep. Recognizing behavioral phenotypes of horses with proble...
Barrantes Murillo DF, Camillo G, Souza Serrano B, Almeida Luciano LP, Castilho Bichara GV, Chaves Vás CA, Furlan Gouvêa FH, Brandini Nespoli PE....Facial abnormalities and brain defects in aborted equine fetuses are rarely reported, and the causes that predispose the occurrence of this condition are difficult to identify. This work reports the morphological and tomographic findings of a case of cryptophthalmia, microphthalmia, oronasal malformation, and hydrocephalus in an aborted equine fetus with umbilical cord torsion in the state of Mato Grosso, Brazil, from a primiparous Quarter Horse female, with 7 months of gestational age. The occurrence of miscarriage was associated with compromised maternal-fetal blood flow due to umbilical cor...
Terhaar HM, Henriksen ML, Mehaffy C, Hess A, McMullen RJ.The objective of this study was to use shotgun label-free tandem mass spectrometry (LF-MS/MS) to evaluate aqueous humor (AH) from horses with uveitis (UH) compared to ophthalmologically healthy horses (HH). Methods: Twelve horses diagnosed with uveitis based on ophthalmic examination and six ophthalmologically healthy horses (postmortem) purchased for teaching purposes. Methods: All horses received a complete ophthalmic examination and physical exam. Aqueous paracentesis was performed on all horses and AH total protein concentrations were measured with nanodrop (TPn) and refractometry (TPr). A...
Woods AC, Chesney AM.A filterable agent has been obtained from the humors and tissues of the eyes of horses suffering from active periodic ophthalmia. The intra-vitreous injection of this filtrate produced in normal horses the same clinical and pathological picture observed in the natural disease. This filtrate injected into rabbits produced a different clinical picture, but the essential pathological lesions closely resembled those found in horses. After passage of the filterable agent through six generations of rabbits, it again produced the clinical and pathological picture of the natural disease when injected ...
Quéré E, Chahory S.Painful eye conditions are a therapeutic challenge in horses. Subpalpebral lavage (SPL) treatment systems allow topical aqueous medications to be conveniently, safely, and frequently administered to the ocular surface. The aim of this retrospective study was to describe the outcomes and the complications associated with the location of the SPL treatment systems, in the superior or inferior eyelid in horses in a university practice. Clinical records of all horses admitted to the National Veterinary School of Alfort between January 2004 and October 2021, in which a SPL treatment system was used ...
Burn JB.The aim of this study was to describe placement of a nictitating membrane flap as a treatment for corneal ulceration and bullous keratopathy in two horses. Methods: A 13-year-old American Saddlebred mare presented for severe corneal edema, superficial stromal ulceration, and a central bulla of the left eye. A 4-year-old Trakhener stallion also presented with a large axial bulla of the left eye with concurrent severe corneal edema and a deep stromal ulcer. Methods: A complete ophthalmic examination was performed. Samples were obtained for corneal cytology, and both horses were started on aggres...
Dwyer AE.Equine practitioners examine patient eyes on a daily basis. Indications range from inspection of normal anatomy to treatment of traumatized eyes to workups of sight threatening inflammatory or neoplastic ocular conditions. Assessment of equine eyes requires practitioners to take time to create a good "exam room" in the field and administer appropriate restraint, sedation and/or regional anesthesia to facilitate thorough examination. Accurate diagnosis and treatment of equine eye problems requires skill in ocular surface staining and cytology, and basic proficiency in standing surgery. Expertis...
Launois T, Hontoir F, Dugdale A, Dedieu M, Vandeweerd JM.Horses with recurrent uveitis can be treated by intravitreal injection of low dose gentamicin under sedation and after local anesthetic techniques including the retrobulbar nerve block. Since it is reported that retinal degeneration can be secondary to an acute increase of intraocular pressure (IOP), the current randomized controlled study was carried out in order to investigate the changes in IOP following retrobulbar anesthesia, with two different volumes of local anesthetic (lidocaine) solution (10 and 5 mL), and intravitreal injection of 6 mg gentamicin in two different volumes of solution...
Regnier A, Landrevie C, Robin MC, Einsweiler D, Douet JY, Raymond-Letron I.A 6-year-old miniature Shetland pony mare was referred for evaluation of a left corneal mass, which developed from the healing tissue of a corneal traumatic ulceration that had occurred 4 weeks previously. On gross examination, a spherical, smooth-surfaced, and pink-colored lesion of about 1 cm in diameter was protruding from the left palpebral fissure. Ophthalmic examination revealed that it was attached to the scar tissue of the cornea, and that one corpora nigra was adherent to the posterior face of corneal wounded area, without sign of uveitis. The remainder of the ophthalmic examinatio...
Ziadi A, Ozmaie S, Asghari A, Rajaei SM.This study aims to assess the effect of topical 0.5% apraclonidine on Intraocular pressure (IOP) in horses and compare the effects of timolol maleate 0.5% with 0.5% apraclonidine in the equine eye. Twenty healthy female thoroughbred horses were used. Horses were divided into two groups. Ten horses received single dose of 0.2 mL of 0.5% apraclonidine in one randomly selected eye and the contralateral eye received single dose of 0.2 mL of artificial tears. In the second group, 10 horses received single dose of 0.2 mL of 0.5% timolol maleate in one eye and the opposite eye received single dose of...
Cooley PL, Milvae R, Riis RC, Laratta LJ.A study was performed to identify prostacyclin (PGI2) in equine aqueous humor, demonstrate an increase in PGI2 following anterior chamber paracentesis, and determine the effects of subconjunctival injection of flunixin meglumine on PGI2 accumulation. Twenty ponies were found to be normal upon ocular examination and were placed under general anesthesia. Anterior chamber paracentesis was performed in both eyes (right and left); immediately afterward, 25 mg of flunixin meglumine was injected (subconjunctivally) in the left eye. Aqueous paracentesis was performed 1.5 hours later (both eyes). Aqueo...
