Veterinary medicine for horses encompasses the study and application of medical practices to diagnose, treat, and prevent diseases in equine species. This field involves a comprehensive understanding of equine anatomy, physiology, pathology, and pharmacology. Veterinary practitioners employ a range of diagnostic tools and therapeutic interventions to address health issues in horses, including lameness, gastrointestinal disorders, respiratory conditions, and infectious diseases. Preventative care, such as vaccination and deworming programs, is also a significant aspect of equine veterinary medicine. This page gathers peer-reviewed research studies and scholarly articles that explore various aspects of veterinary medicine as it pertains to horses, including advancements in diagnostic techniques, treatment protocols, and preventive health strategies.
Doxey DL, Milne EM, Ellison J, Curry PJ.Responses to questionnaires were received from 31 owners of horses or ponies treated for chronic grass sickness (dysautonomia). Contrary to previous opinions the respondents indicated that the majority of the animals were capable of strenuous work, had regained the weight they had lost and, apart from a few residual problems such as difficulty in coping with dry fibrous food, had returned to a normal life. They had recovered slowly and had involved the owners in considerable extra work, but all the owners indicated that they considered the effort to have been worthwhile.
Friend TH, Martin MT, Householder DD, Bushong DM.To characterize progressive patterns of dehydration, stress responses, and water consumption in horses transported long distances in hot weather and to evaluate various measurements in detecting dehydration and stress in transported horses. Methods: Prospective study. Methods: 30 mature, healthy horses. Methods: The following 4 treatment groups were studied: horses that were penned and offered water every 5 hours (n = 5), horses that were penned and not offered water (5), horses that were transported in a truck and offered water every 5 hours (10), and horses that were transported and not offe...
Rebhun WC, Del Piero F.To determine the most common ocular lesions in horses with lymphosarcoma. Methods: Retrospective study. Methods: 79 horses histologically confirmed to have lymphosarcoma. Methods: Ophthalmic examinations were performed by a single individual. Results: 21 of 79 horses had lesions involving the eye or ocular adnexa. Infiltration of the palpebral conjunctiva and eyelids was the most common lesion (n = 11). Other lesions included uveitis (n = 4), corneoscleral masses (2), third eyelid masses (2), and diffuse retrobulbar infiltrates (2). Conclusions: In horses with lymphosarcoma, ocular lesions may...
Bouré L, Marcoux M, Lavoie JP, Laverty S.Exploratory laparoscopy of the right dorsal portion of the abdominal cavity was performed on a Standardbred filly because of signs of mild abdominal pain of 7 days' duration. On the basis of clinical examination, diagnosis was suppurative peritonitis, abdominal adhesions in the area of the right ovary, and right displacement and impaction of the pelvic flexure of the ascending colon. During laparoscopy, an abdominal adhesion between the right uterine horn, the cecum, and the pelvic flexure was identified. The abdominal adhesions were either stretched with laparoscopic forceps used as a probe o...
Walker MA, Schumacher J, Schmitz DG, McMullen WC, Ruoff WW, Crabill MR, Hawkins JF, Hogan PM, McClure SR, Vacek JR, Edwards JF, Helman RG, Frelier PF.Three adult horses underwent aggressive treatment of squamous cell carcinoma of the nasal cavity and paranasal sinuses, using course-fractionated cobalt 60 radiotherapy. Squamous cell carcinoma of the nasal cavity and paranasal sinuses is not commonly diagnosed in horses. Historically, horses with this type of neoplasm have not been treated or have undergone some form of surgery. The prognosis for long-term survival or cure has been poor. Long-term results of cobalt 60 radiotherapy were good to excellent and exceeded those usually reported for horses treated surgically. On the basis of these r...
Ludewig T.Corpora amylacea are present in all the mammary glands of the investigated animals (ewe, goat, and mares). Generally, they are comparable to the cow regarding to its distribution, frequency, size, morphological structure, and staining properties. Corpora amylacea occur most frequently in the ewe, and in non-lactating mammary glands. In lactating mammary glands they are mostly situated in the alveoles. During gestation they are located outside of the alveoles and in the interalveolar connective tissue. Only in very few cases corpora amylacea are found inside and outside of the alveoles in the s...
Brugmans F, Venner M, Menzel D, Mischke R.The purpose of this study was to investigate the usefulness of two heat-precipitation techniques (Schalm- and Millar-method) as screening tests to measure plasma fibrinogen concentration in horses. Based on the measurement of samples from 108 different horses, the coefficient of correlation (CC) for the relationship between the results with the Schalm- and with the reference-method (Jacobsson) were much lower (r = 0.78) than between the Millar- and Jacobsson-method (r = 0.94). Furthermore the Schalm-method was less precise as reflected by the greater coefficient of variation (CV, within-run pr...
Carpenter TE, McBride MD, Hird DW.We examined the risk of importing and mistakenly releasing equine infectious anemia virus (EIAV)-infected horses into California. A computer simulation model was constructed to evaluate current and alternative quarantine station procedures; 150,000 iterations were performed to simulate 15 different scenarios of 10,000 horses imported into the state over a 14-year period. Simulation results showed that under current conditions of low EIAV prevalence in exporting countries, increasing the quarantine period would not decrease the number of EIAV-infected horses mistakenly released from quarantine....
Witham CL, Stull CL.To examine metabolic responses of chronically starved horses to refeeding with 3 isoenergetic diets. Methods: Uncontrolled clinical trial. Methods: 22 mature mixed-breed horses that were emaciated but otherwise clinically normal. Methods: Horses were fed 1 of 3 diets: alfalfa hay, oat hay, or a combination diet of half oat hay and half commercially prepared ration. Digestible energy of diets was gradually increased throughout the refeeding period. One pre- and 4 postprandial blood samples were obtained daily, and analyses included RBC count, Hct, and determination of hemoglobin, glucose, insul...
Veeramachaneni DN, Sawyer HR.The presence of atypical germ cells resembling carcinoma in situ of human testis is reported for the first time in an unilaterally cryptorchid stallion. These cells were found in association with developing intratubular seminoma indicating they represented carcinoma in situ.
Sedrish SA, Moore RM, Kelly K, Martin GS, Burba DJ.To determine and compare the in vitro pullout strength of 5.5-mm cortical versus 6.5-mm cancellous bone screws inserted in the diaphysis and metaphysis of adult equine third metacarpal (MCIII) bones, in threaded 4.5-mm cortical bone screw insertion holes that were then overdrilled with a 4.5-mm drill bit to provide information relevant to the selection of a replacement screw if a 4.5-mm cortical screw is stripped. Methods: In vitro pullout tests of 5.5-mm cortical and 6.5-mm cancellous screws in equine MCIII bones. Methods: Two independent cadaver studies each consisting of 14 adult equine MCI...
Damiani AM, Matsumura T, Yokoyama N, Maeda K, Miyazawa T, Kai C, Mikami T.The nucleotide sequences of the glycoprotein I (gI) and E (gE) genes of equine herpesvirus type 4 (EHV-4) strain TH20 were determined. The predicted region encoding the EHV-4 gI gene is 1,263 nucleotides, corresponding to a polypeptide of 420 amino acids in length. The predicted region encoding the EHV-4 gE gene is 1,647 nucleotides, corresponding to a polypeptide of 548 amino acids in length. The EHV-4 gI and gE genes show 74% and 85% identity at the amino acid level with those of equine herpesvirus type 1 (EHV-1), respectively. Furthermore, we have found an open reading frame homologous to t...
Hughes FE, Slone DE.To describe an alternative technique for large colon resection and anastomosis in horses. Methods: Retrospective study of clinical patients. Methods: 37 horses that had ventral midline celiotomies between July 1, 1990, and July 1, 1994. Methods: Large colon resection and anastomosis was performed using a modification of previously described techniques. Modifications include mesocolon ligation with a stapling device and an end-to-end apposition of the right ventral and right dorsal colon. Results: Twenty-one of the 37 horses were discharged from the hospital without complications. Two horses we...
Ragle CA, Southwood LL, Howlett MR.To report a ventral abdominal approach and a ligating loop technique for laparoscopic cryptorchidectomy in horses. Methods: Prospective. Methods: Six horses, aged 1 to 5 years, with retained testes. Methods: One laparoscopic portal and three to four instrument portals were used for ventral abdominal laparoscopic cryptorchidectomy. Laparoscopic instruments were used to maneuver and secure the testis through a ligating loop (modified Roeder knot) that was secured from outside the abdominal cavity. Only minimal enlargement of one instrument portal was used to remove the testicle. Results: Three h...
Hague BA, Honnas CM, Berridge BR, Easter JL.To evaluate the postoperative use of peritoneal lavage for prevention of experimentally induced intraabdominal adhesions in horses. Methods: Areas of serosal abrasion were created on the jejunum of 12 horses. Postoperatively, six horses had peritoneal lavage, and six horses did not (controls). The number of adhesions was determined at necropsy 2 weeks after surgery. Methods: 12 horses. Methods: Five sites of jejunal serosal abrasion were created in each horse. A 32 French thoracic catheter was placed into the right ventral aspect of the abdomen before closure of the abdominal incision. Treated...
Southwood LL, Stashak TS, Kainer RA.To describe the tenoscopic anatomy of the carpal sheath of the flexor tendons (carpal sheath) viewed from a lateral approach. Methods: Tenoscopic observation of structures within the carpal sheath subsequently confirmed by dissection. Methods: 12 equine cadaveric forelimbs. Methods: The limbs were positioned lateral side up with the carpus slightly flexed. After distention of the carpal sheath, a portal for the arthroscope was made approximately 3 cm proximal to the distal radial physis and 2.5 cm caudal to the radius between the tendons of the ulnaris lateralis and lateral digital extensor mu...
Tan JH, Nanbo Y, Oikawa M, Kiso Y, Sasaki F.To analyze the sex difference in 6 kinds of adenohypophyseal cells of Mongolian ponies and the effect of prepubertal orchidectomy on adenohypophyseal cells. Methods: Pituitary glands collected from 15 adult Mongolian ponies, 5 to 10 years old: 5 stallions, 5 mares, and 5 geldings, orchidectomized between the ages of 1 and 2 years. Methods: Morphologic comparison of 6 kinds of adenohypophyseal cells among mares, stallions, and geldings was done, using immunocytochemistry and morphometry. Results: A sex difference was evident in the percentage of somatotrophs, gonadotrophs (follicle-stimulating ...
Kooreman K, Babbs C, Fessler J.To evaluate and compare oxidative processes during ischemia and reperfusion of the equine large colon and jejunum. Methods: 2 groups of 6 anesthetized horses undergoing a terminal procedure. Methods: Isolated loops of large colon and jejunum were subjected to 2 hours of ischemia, followed by 2 hours of reperfusion. Tissue specimens were taken after 105 minutes of ischemia and 10, 30, 60, and 120 minutes of reperfusion. Mesenteric arterial and venous blood samples were collected for blood gas analysis at the same times to evaluate ischemia and reoxygenation. Oxidative processes in tissues were ...
Becker CK, Savelberg HH, Buchner HH, Barneveld A.To evaluate clinical and biomechanical consequences of desmotomy of the accessory ligament (AL) of the deep digital flexor tendon (DDFT) of equine forelimbs and determine whether this procedure is a viable treatment for chronic desmitis of the AL-DDFT. Methods: 6 adult Standardbred trotters. Methods: Biomechanical recordings obtained before and 6 months after desmotomy were compared. Walk and trot joint angles, ground reaction forces, peak joint moments, and tendon forces were assessed. Results: Within 10 days after surgery, all horses were sound at a trot. Swelling, increased carpal flexion i...
Moens Y, Lagerweij E, Gootjes P, Poortman J.To study effects of intermittent positive-pressure ventilation (IPPV) with large tidal volumes and addition of positive end-expiratory pressure (PEEP) on maldistribution of ventilation in anesthetized horses positioned in lateral recumbency. Methods: 6 healthy adult horses. Methods: Anesthesia was induced by i.v. infusion of thiopental sodium and guiafenesin and was maintained with supplemental doses of thiopental and i.v. infusion of chloral hydrate. Functional separation of the lungs was achieved, using a tube-in-tube intubation technique. Intermittent positive-pressure ventilation of both l...
Lester GD, Merritt AM, Neuwirth L, Vetro-Widenhouse T, Steible C, Rice B.To determine effect of xylazine hydrochloride (XYL), yohimbine hydrochloride (YOH), bethanechol chloride (BET), neostigmine methyl sulfate (NEO), or flunixin meglumine (FLU) on ileocecocolic myoelectric activity and passage of radiolabeled markers from the cecum. Methods: 6 healthy adult ponies. Methods: A cecal cannula was surgically implanted, and 12 were sutured to the ileum, cecum, and right ventral colon. After a 12-hour nonfeeding period, 370 MBq of technetium 99m-labeled sulfur colloid in egg albumen and 37 MBq of indium 111-labeled diethyltriaminepentaacetic acid in 60 ml of water were...
Becker CK, Savelberg HH, Buchner HH, Barneveld A.To evaluate posttrauma biomechanical behavior of the scar attributable to desmotomy of the accessory ligament of the deep digital flexor tendon (AL-DDFT), compared with the histomorphologic and ultrasonographic appearance. Methods: 5 Standardbred trotters. Methods: Gross appearance, length, cross-sectional area (CSA), in vitro material properties, and ultrasonographic and histomorphologic features were studied 6 months after desmotomy. Tensile tests were conducted, with forces and elongation simultaneously recorded. Surgically treated limbs were compared with nontreated contralateral limbs. Re...
Lester GD, Merritt AM, Neuwirth L, Vetro-Widenhouse T, Steible C, Rice B.To determine the effect of erythromycin lactobionate (ERY) on ileocecocolic myoelectric activity and passage of radiolabeled markers from the cecum. Methods: 6 healthy adult ponies. Methods: After a 12-hour nonfeeding period, 370 MBq of technetium 99m-labeled sulfur colloid in egg albumen and 37 MBq of indium 111-labeled diethyltriaminepentaacetic acid in 60 ml of water were administered directly into the cecal apex. The following drug concentrations were tested: ERY, 0.01, 0.10, 1.0, and 10.0 mg/kg of body weight; ERY, 0.10 mg/kg bolus; and saline (0.9% NaCl) solution, 10 ml. All treatments, ...
Dyke TM, Sams RA, Hinchcliff KW.To measure renal clearance of antipyrine and urinary excretion of antipyrine (AP) metabolites in horses by use of validated high-performance liquid chromatography (HPLC) methods. Methods: 8 Standardbred mares. Methods: HPLC methods for measurement of AP in equine plasma and AP and its metabolites in equine urine were validated. Antipyrine (20 mg/kg of body weight) was administered i.v., and blood samples and urine specimens were collected over 24 hours. Results: Median plasma clearance of AP in horses was 6.2 ml/min/kg, of which < 2% could be attributed to renal clearance. Urinary excretion...
Hill AE, Carpenter TE, Gardner IA, Stover SM.To evaluate a Markov-chain model for the development of forelimb injuries in Thoroughbreds and to use the model to determine effects of reducing sprint distance on incidence of metacarpal condylar fracture (CDY) and severe suspensory apparatus injury (SSAI). Methods: Weekly exercise and injury data for 122 Thoroughbreds during racing or training. Methods: Weekly data were used to construct a Markov-chain model with 5 states (uninjured [UNINJ], palpable suspensory apparatus injury [PSAII, SSAI, CDY, and lost to follow-up [LOST]). Transition probabilities between UNINJ and PSAI were estimated as...
Liu IK, Cheung AT, Walsh EM, Miller ME, Lindenberg PM.The functional competence of peripheral blood and uterine-derived polymorphonuclear leukocytes (PMN) from 12 mares were analyzed for chemotactic responsiveness using a chemotactic chamber (filter) assay and for deformability by cell elastimetry analysis. Peripheral blood PMN obtained from control mares and from 8 mares experimentally inoculated via the uterus with 1 x 10(9) Streptococcus zooepidemicus had similar normal chemotactic responsiveness and were highly deformable before and at 12 hours after inoculation. Uterine PMN obtained 12 hours after uterine inoculation with S zooepidemicus fro...
Houben RMAC, Meersschaert C, Hendrickx G, Pitel PH, Amory H.Serological screening tests for Lyme borreliosis have poor specificity, with potential for misdiagnosis and unnecessary antimicrobial treatment. Objective: To evaluate the impact of Lyme borreliosis seroprevalence and serologic test characteristics on the probability of obtaining a false-positive result and impact on antimicrobial use. Methods: Cross-sectional serological survey and modelling. Methods: Sera from 303 horses in southern Belgium were analysed by enzyme-linked immunosorbent assay (ELISA). Apparent seroprevalence was derived from serological data and a Bayesian estimate of true ser...
Fontanals AM, Becú T, Polledo G, Gaskin CK, Braun M.An R. equi vaccine, prepared under conditions which induce the expression of many antigens, and which has given encouraging results in field trials, was analyzed by SDS-PAGE and immunoblots and compared with other R. equi preparations: a preparation made in with the same technique from a nonvirulent isolate (virulence associated protein negative, VapA-negative); a whole cell preparation of a VapA-positive R. equi, prepared as a standard bacterin; and a semipurified VapA preparation (APTX). The antigens in these preparations were analyzed using hyperimmune sera (from adult horses vaccinated wit...
Matczuk AK, Chodaczek G, Ugorski M.Equine arteritis virus (EAV) is a prototype member of the Arterivirus family, comprising important pathogens of domestic animals. Minor glycoproteins of Arteriviruses are responsible for virus entry and cellular tropism. The experimental methods for studying minor Arterivirus proteins are limited because of the lack of antibodies and nested open reading frames (ORFs). In this study, we generated recombinant EAV with separated ORFs 3 and 4, and Gp3 carrying HA-tag (Gp3-HA). The recombinant viruses were stable on passaging and replicated in titers similar to the wild-type EAV. Gp3-HA was incorpo...
LeBlanc MM, McLaurin BI, Boswell R.Postpartum, presuckle, colostrum samples were collected from 100 mares. Colostral specific gravities significantly correlated (r = 0.9) with colostral immunoglobulin (Ig)G concentrations. Foal serum IgG concentrations highly correlated (r = 0.82) with specific gravities of the colostrum each foal ingested. Eight of 48 foals (17%) had serum IgG concentrations less than 400 mg/dl. The dams of these 8 foals had colostral sp gr less than 1.06 and colostral IgG concentrations less than 3,000 mg/dl. Foals had serum IgG concentrations greater than 520 mg/dl 24 hours after parturition, when the colost...
Iwaszko A, Borowicz H, Graczyk S, Slowikowska M, Pliszczak-Krol A, Niedzwiedz A.Recurrent airway obstruction (RAO), also known as heaves, is an allergic respiratory condition that develops in horses following an exposure to aeroallergens in hay and straw. This is manifested by airway hyperreactivity, inflammation, bronchoconstriction, as well as a leukocyte and platelet infiltration into the airways. Platelet activation and an increase in circulating platelet-leukocyte aggregates may lead to airway remodeling. The aim of this study was to explore the effect of seven-day antigen challenge on dynamics of platelet indices and CD41/61 and CD62 P expression on platelets in h...
Pressanto MC, Pascoletti G, Perkins JD, Zanetti EM, Beccati F, Santalucia V, Pepe M.To validate the use of a polyblend tape suture in equine laryngoplasty (PL). Methods: Experimental study. Methods: Thirty-two cadaveric larynges. Methods: Each larynx was randomly assigned to 1 of 4 groups: PL with polyblend tape suture (TigerTape), without (TT) or with a cannula (TTC) in the muscular process of the arytenoid cartilage, and PL with polyester suture (Ethibond), without (EB) or with a cannula (EBC). Construct stiffness, total migration, creep, and drift values were measured after 3000 cycles. The specimens were then loaded to failure to assess their residual properties: load a...
Pauwels FE, Adams SB, Blevins WB.Two horses with lameness due to tolocalcaneal osteoarthritis that failed to respond to conservative management were treated by tolocalcaneal arthrodesis using cortex screws placed in lag fashion. The affected joint of one horse was arthrodesed by compressing and stabilizing the medial facet of the joint with three screws. In the second horse, the medial and lateral facets of the affected tolocalcaneal joint were each compressed and stabilized with two screws. The lameness of both horses improved markedly following surgery.
Wattle OS.To determine whether there is a change in the expression of cytokeratins in the epidermal cells of the non-weight-bearing parts of the limb in horses with acute laminitis and thus determine whether the morphologic changes that develop in the periople and chestnut (torus carpeus) of horses early in acute laminitis are caused by inhibition of keratinocyte differentiation. Methods: 8 horses with acute laminitis. Methods: Tissue specimens were obtained from the chestnuts of all 8 horses and from the stratum externum of the hoof wall of 3 horses. Tissue specimens were obtained within 48 hours of th...
Watson ED.Incubation of blood neutrophils with uterine flushings collected from ovariectomised mares treated with oestradiol, stimulated migration under agarose, whereas flushings from mares treated with progesterone or oily vehicle, inhibited migration. After intra-uterine infusion of bacteria, however, flushings from oestradiol-treated and vehicle-treated mares inhibited migration, whereas progesterone treatment stimulated migration. Migration of uterine-derived neutrophils under agarose was less than that of blood neutrophils and was not influenced by treatment with ovarian steroids. Uterine suscepti...
Raz T, Gray A, Hunter B, Card C.Superovulatory treatment may potentially increase the embryo recovery rate and the per-cycle pregnancy rate in normal or subfertile mares that are managed properly. However, some studies suggest a possible negative effect of superovulatory treatment on ovarian follicular maturation and embryo viability. Objectives of the present study were to investigate the early effects of eFSH treatment in reproductively normal mares in terms of: folliculogenesis, pregnancy rate, early embryonic development, reproductive tract parameters (tone and edema), and serum estradiol-17beta and progesterone concentr...
Justines G, Oro G, Alvarez O.The P-676 and MF-8 epizootic strains of Venezuelan equine encephalitis (VEE) virus were found to contain a minute plaque (MP), different from the predominant small plaque (SP) present in these virus strains. The MP and SP were stable after passages in Vero cells, mice, or horses. Equines were inoculated with the SP or MP of the P-676 and MF-8 strains. Inoculation of either P-676 SP or MP into horses induced high fever and viremia but no signs of encephalitis or death. Four horses infected with MF-8 SP became very ill, with high fever and viremia; three of the inoculated animals died. Four hors...
Bravo Mendiburt G, Agostini V, Cañete Betancourt G.In this paper a morphological differentiation tool of bovine and equine hair for their identification in forensic investigations is provided. 30 animals were used, fifteen adult bovines of the "Siboney de Cuba" breed and fifteen adult equines of the "Criolla" breed. These species are the most bred in Cuba and, at the same time, the most exposed to poaching and theft crimes. Hair from the cows was sampled from the dorsal region, the lateral region and the ventral region; on the other hand, the horses' hair was sampled from the dorsal region of the body, of the mane and of the tail. The sampled ...
Moore EN, Spear JF.We tested the multiple-wavelet hypothesis by studying the initiation and maintenance of atrial fibrillation in normal mules, horses, cows, calves, and goats. Persistence of atrial fibrillation in animals with a large atrial mass was compared with results in adult goats and calves having a smaller atrial mass. Atrial stimulation in clinically normal cows, mules, calves, and goats was accomplished using an intra-atrial stimulating catheter with rapid atrial pacing (30/s). Once initiated, atrial fibrillation persisted for 95,120,125 min, 3 days, and 8 weeks in five adult cows, respectively. In co...
Apprich V, Licka T, Freiler S, Gabriel C.Impaired keratinocyte differentiation has recently been suggested as a key event in equine hoof canker development. Koilocytotic appearance of keratinocytes, one of the most characteristic morphological alterations in hoof canker tissue, is also a common marker for papillomavirus (PV) infection, and bovine PV-1 and/or -2 (BPV-1/2) has previously been detected in equine canker patients. Therefore, the present study aimed to correlate the frequency and severity of koilocytotic keratinocytes with BPV detection in hoof canker samples. Hoof tissue of 5/18 canker-affected horses and 2/6 control hors...
Savage CJ, Traub-Dargatz JL, Mumford EL.A survey designed to obtain information on the indications, contraindications, complications, and methodology of percutaneous lung biopsy in the horse was sent to large animal diplomates of the American College of Veterinary Internal Medicine. Sixty-five of 190 diplomates returned the survey (response rate: 34%) and 59 of these 65 respondents (91%) indicated that they worked with horses. Forty-four diplomates had performed a percutaneous lung biopsy in 1 or more horses (i.e. 75% of those diplomates working with horses and 68% of total respondents). Clinical and radiologic diagnoses that prompt...
Malalana F.Ocular abnormalities are a common finding in aged horses. Although these seldom cause overt visual deficits detected by their owners, they can be a source of chronic or acute discomfort so early detection, and treatment when available, is essential. Some of these abnormalities are specific to old horses, whereas others are a result of ongoing disease or inflammation that started earlier in life but that becomes more evident when the damage sustained to the eye is advanced. If vision is significantly affected, consideration of human safety and animal welfare is paramount.