Fernando Malalana

Mitomycin C, with or without surgery, for the treatment of ocular squamous cell carcinoma in horses

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 of treatment followed by seven days without treatment. This was repeated until full regression of the tumour occurred (up to four rounds of treatment with mitomycin C). Of the eight eyes treated with mitomycin C alone (without surgery), clinical resolution occurred in six cases. Of the nine eyes treated with a combination of surgery and topical mitomycin C, clinical resolution occurred in seven cases. No complications were observed.

Equine recurrent uveitis: Human and equine perspectives.

Equine recurrent uveitis (ERU) is a spontaneous disease characterised by repeated episodes of intraocular inflammation. The epidemiology of ERU has not been fully elucidated, but the condition appears to be much more common in horses than is recurrent uveitis in humans, especially in certain breeds and geographical regions. Both humans and horses show a similarly altered immune response and a marked autoimmune response as the primary disease pathophysiology. However, an inciting cause is not always clear. Potential inciting factors in horses include microbial agents such as Leptospira spp. Microbial factors and genetic predisposition to the disease may provide clues as to why the horse appears so susceptible to this disease. The aim of this review is to discuss the immunology and genetics of ERU, compare the disease in horses with autoimmune anterior uveitis in humans, and discuss potential reasons for the increased prevalence in the horse.

ANATOMICAL STUDY OF CRANIAL NERVE EMERGENCE AND SKULL FORAMINA IN THE HORSE USING MAGNETIC RESONANCE IMAGING AND COMPUTED TOMOGRAPHY

For accurate interpretation of magnetic resonance (MR) images of the equine brain, knowledge of the normal cross-sectional anatomy of the brain and associated structures (such as the cranial nerves) is essential. The purpose of this prospective cadaver study was to describe and compare MRI and computed tomography (CT) anatomy of cranial nerves origins and associated skull foramina in a sample of five horses. All horses were presented for euthanasia for reasons unrelated to the head. Heads were collected posteuthanasia and T2-weighted MR images were obtained in the transverse, sagittal, and dorsal planes. Thin-slice MR sequences were also acquired using transverse 3D-CISS sequences that allowed mutliplanar reformatting. Transverse thin-slice CT images were acquired and multiplanar reformatting was used to create comparative images. Magnetic resonance imaging consistently allowed visualization of cranial nerves II, V, VII, VIII, and XII in all horses. The cranial nerves III, IV, and VI were identifiable as a group despite difficulties in identification of individual nerves. The group of cranial nerves IX, X, and XI were identified in 4/5 horses although the region where they exited the skull was identified in all cases. The course of nerves II and V could be followed on several slices and the main divisions of cranial nerve V could be distinguished in all cases. In conclusion, CT allowed clear visualization of the skull foramina and occasionally the nerves themselves, facilitating identification of the nerves for comparison with MRI images.

Elevations in serum muscle enzyme activities in racehorses due to unaccustomed exercise and training

Hereditary muscular disease is well described in racehorses, yet little is known about traumatic muscle disease associated with unaccustomed exercise or training. The objective of the study was to compare sedentary horses, racehorses undergoing training for the first time (unaccustomed exercise), and experienced racehorses during a training season (accustomed exercise) to investigate the effect of exercise and training on serum muscle enzyme activities and other variables. Horses were sampled prior to exercise for serum activities of aspartate amino transferase (AST), creatine kinase and other variables γ glutamyl transferase (GGT) and serum amyloid A (SAA) in a three-part study. Serum activities of AST and GGT were higher in fit racehorses (n=47) compared with sedentary horses (n=57) at a single time point (P<0.05). The monthly serum activity of AST in two-year-old racehorses (n=10) increased from month 1 to 4 of unaccustomed training (P<0.05). The serum activities of AST and GGT in three-year-old racehorses (n=12) previously accustomed to exercise sampled fortnightly to monthly showed a linear increase (P<0.05) with cumulative training days over the seven months of training, but showed minimal increase during the first four months of accustomed training. SAA was weakly correlated to cumulative training days. In conclusion, AST activity was increased by unaccustomed exercise and cumulative training stress in the racehorse. GGT appeared to be correlated to cumulative training load. Mild to moderate elevations in serum AST in racehorses may be associated with cumulative muscle damage from training or trauma associated with unaccustomed exercise.

Nephrogenic diabetes insipidus in a 14-year-old gelding

Abstract CASE HISTORY: A 14-year-old Cleveland Bay cross gelding was presented with severe urinary incontinence that had been present for 1 year, and chronic polydipsia and polyuria over 4 years. Water intake had been recorded as 240 L over a 24-hour period. CLINICAL FINDINGS: The horse had marked urinary incontinence and polyuria and polydipsia. The urine was markedly hyposthenuric, but no abnormalities on urinalysis were detected. There were no other abnormal clinical or neurological signs. Haematological and serum biochemical examinations showed no abnormalities and ultrasonographic and endoscopic examination of the urinary tract did not reveal any abnormalities. The horse underwent a modified water deprivation test and failed to concentrate its urine after 5 days. 1-desamino-8-d-arginine vasopressin (DDAVP) was administered I/V but the urine remained isosthenuric with a specific gravity of 1.010. DIAGNOSIS: Nephrogenic diabetes insipidus. A definitive cause of the urinary incontinence was not found but overflow incontinence was considered a possibility. CLINICAL RELEVENCE: Despite being a rare condition in the horse diabetes insipidus should be considered in cases of severe polydipsia and polyuria in mature horses.

The role of Leptospira spp. in horses affected with recurrent uveitis in the UK

Summary Background Equine recurrent uveitis (ERU) is a common cause of ocular pain and blindness in horses. Leptospira spp. have been commonly implicated in the pathophysiology of ERU in mainland Europe and the USA. No recent studies have been carried out in the UK, but Leptospira is reported not to be a major factor in the aetiology of ERU in the UK. Objectives To establish the prevalence of Leptospira‐associated ERU in the UK and to identify the serovars involved in these cases; to compare serum vs. aqueous humour antibody levels in cases and controls in order to confirm the diagnosis of Leptospira‐associated ERU, and to assess the usefulness of serology alone as a confirmatory test for Leptospira‐associated ERU in the UK. Study design Case–control study. Methods Eyes enucleated for clinical reasons in ERU‐affected horses were collected. Blood and aqueous humour were obtained to determine antibody levels against a variety of Leptospira serovars and C‐values (aqueous humour value/serum value) were calculated. In addition, eyes, blood and aqueous humour were obtained from control cases for comparison. Histopathology was performed in all eyes to confirm uveitis in each case. Differences in seroprevalences between ERU and control cases and between Leptospira‐ and non‐Leptospira‐associated ERU cases were calculated. Results A total of 30 ERU and 43 control eyes were analysed. Of the ERU eyes, only two had a C‐value of >4 (prevalence of Leptospira‐associated uveitis: 6.7%). Serovars hardjo and javanica were detected. There was no difference in seroprevalence between horses with uveitis and control cases (65.5% and 41.9%, respectively; P = 0.11) or between Leptospira‐ and non‐Leptospira‐associated uveitis cases (100% and 63.0%, respectively; P = 0.52). Main limitations The study was limited by low case numbers. Eyes were presented at different stages of disease. The only test used to detect Leptospira was the microscopic agglutination test. Conclusions Leptospira‐associated ERU is uncommon in the UK. Serology alone may not help to definitively diagnose Leptospira‐associated uveitis in this country.

Episcleral cyclosporine A implants for the management of unilateral keratoconjunctivitis sicca in an 8‐year‐old mare

An 8-year-old mare was presented for investigation of a 1-month history of blepharospasm, eyelid swelling, corneal edema, and ocular discharge of the right eye (OD). Ophthalmic examination confirmed mucopurulent ocular discharge, conjunctival hyperemia, and a dry, dull appearance to the cornea OD. Schirmer tear test results confirmed an absence of tear production OD (0 mm/min) consistent with keratoconjunctivitis sicca. Treatment with topical 0.2% cyclosporine A resulted in an improvement in clinical signs. An episcleral cyclosporine A implant was placed under standing sedation 5 days after initial presentation. Re-examination 9 days post-operatively confirmed that the mares tear production in the right eye had improved and no further clinical signs had been observed. Topical medications were gradually discontinued. Re-examinations performed up to 12 months postsurgery showed no recurrence of clinical signs and no adverse effects of the implant. To our knowledge, this is the first report of the use of a cyclosporine A implant in the management of KCS in a horse and highlights its potential as an effective, alternative therapy in the management of KCS in horses.

Retrospective evaluation of 155 adult equids and 21 foals with tetanus from Western, Northern, and Central Europe (2000–2014). Part 2: Prognostic assessment

OBJECTIVEnTo identify prognostic variables for adult equids and foals with tetanus.nnnDESIGNnMulticenter retrospective study (2000-2014).nnnSETTINGnTwenty Western, Northern, and Central European university teaching hospitals and private referral centers.nnnANIMALSnOne hundred fifty-five adult equids and 21 foals with tetanus.nnnINTERVENTIONSnNone.nnnMEASUREMENTS AND MAIN RESULTSnVariables from history and clinical examination were statistically compared between survivors and nonsurvivors (adults: 49 survivors, 85 nonsurvivors; foals: 7 survivors, 10 nonsurvivors). Cases euthanized for financial reasons were excluded. Mortality rates in adults and foals were 68.4% and 66.7%, respectively. Variables associated with survival in adults included: standing, normal intestinal sounds and defecation, voluntarily drinking, eating soft or normal food, lower heart and respiratory rates, high base excess on admission, longer diagnosis time, treatment and hospitalization delay, and mild severity grade. Variables associated with death included: anorexia, dysphagia, dyspnea, low blood potassium concentration on admission, moderate and severe disease grading, development of dysphagia, dyspnea, recumbency and seizures during hospitalization, treatment with glycerol guaiacolate, intravenous fluids, and intravenous glucose solutions. Variables associated with survival in foals included standing on admission, voluntarily eating soft food and drinking, older age, and longer hospitalization delay. Outcome was not different between different tetanus antitoxin (TAT) dosages, although there was a trend of increasing survival rate with increasing TAT dosages. Cases with appropriate vaccination prior to development of tetanus were rare, but had improved outcome and shorter hospitalization.nnnCONCLUSIONSnPrognosis for equine tetanus is poor with similar outcome and prognostic factors in foals and adults. The prognostic assessment of cases with tetanus provides clinicians with new evidence-based information related to patient management. Several prognostic indicators relate to the ability to eat or drink, and more severe clinical signs relate to poor outcome. Increasing intravenous dosages of TAT has no significant effect on outcome, but the positive trend identified may support a recommendation for high intravenous TAT dosages. Further evaluation is warranted.

Retrospective evaluation of 155 adult equids and 21 foals with tetanus in Western, Northern, and Central Europe (2000–2014). Part 1: Description of history and clinical evolution

OBJECTIVEnTo describe clinical data of hospitalized adult equids and foals with tetanus.nnnDESIGNnMulticenter retrospective study (2000-2014).nnnSETTINGnTwenty Western, Northern, and Central European university teaching hospitals and private referral centers.nnnANIMALSnOne hundred fifty-five adult equids (>6 months) and 21 foals (<6 months) with tetanus.nnnINTERVENTIONSnNone.nnnMEASUREMENTS AND MAIN RESULTSnInformation on geographic, annual and seasonal data, demographic- and management-related data, clinical history, clinical examination and blood analysis on admission, complications, treatments, and outcomes were described and statistically compared between adults and foals. The described cases were often young horses. In 4 adult horses, tetanus developed despite appropriate vaccination and in 2 foals despite preventive tetanus antitoxin administration at birth. Castration, hoof abscesses, and wounds were the most common entry sites for adults; umbilical cord infections and wounds for foals. Stiffness was the commonest observed initial clinical sign. Blood analyses frequently revealed an inflammatory response, hemoconcentration, muscle damage, azotemia, negative energy balance, liver damage, and electrolyte and acid base disturbances. Common complications or clinical signs developing during hospitalization included dysphagia, dyspnea, recumbency, hyperthermia, seizures, hyperlipemia, gastrointestinal impactions, dysuria, and laryngeal spasms. Cases were supported with wound debridement, antimicrobial treatment, tetanus antitoxin, muscle spasm and seizure control, analgesia, anti-inflammatory drugs, fluid therapy, and nutritional support. Mortality rates were 68.4% in adult horses and 66.7% in foals. Foals differed from adult horses with respect to months of occurrence, signalment, management-related data, potential causative events, clinical signs on admission, blood analysis, complications, and severity grades.nnnCONCLUSIONSnThis is the first study that rigorously describes a large population of equids affected by tetanus. The information provided is potentially useful to clinicians for early recognition and case management of tetanus in adult horses and foals. Tetanus affects multiple organ systems, requiring broad supportive and intensive care. Neonatal and adult tetanus in the horse should be considered as distinct syndromes, as in human medicine.

Corneal abrasion and microbial contamination in horses following general anaesthesia for non-ocular surgery

OBJECTIVEnTo evaluate the incidence of corneal abrasions/ulceration and microbial contamination in horses undergoing general anaesthesia.nnnSTUDY DESIGNnProspective, observational, clinical study.nnnANIMALSnA total of 40 client-owned healthy horses scheduled for elective non-ophthalmic procedures.nnnMETHODSnConjunctival sac swabs were taken, fluorescein dye applied and digital images recorded from both eyes of the horses after preanaesthetic medication and 24 hours after recovery from general anaesthesia. A paraffin-based bland ophthalmic ointment was applied on the ocular surface intraoperatively following collection of a sample into a sterile container. All samples underwent aerobic, anaerobic and fungal culture. Subject demographics, chronology of ophthalmic ointment use, anaesthesia duration, recumbency after induction, during surgery and recovery, fluorescein uptake and culture results were recorded. Descriptive statistics were performed.nnnRESULTSnComplete data were collected from 34 horses; six (17.6%) developed mild unilateral generalized fluorescein uptake consistent with corneal abrasions. Recumbency on the operating table was the only risk factor significantly associated with corneal abrasions. A total of 11 bacterial species were identified; Staphylococcus spp. (15 eyes) and Micrococcus spp. (eight eyes) were the most frequently isolated bacteria. Two fungal species were isolated postoperatively (Aspergillus spp., Saccharomyces spp.) in two eyes. Ointment contamination was recorded in two cases (5%) but cross-contamination was not recognized.nnnCONCLUSIONSAND CLINICAL RELEVANCEnIncidence of corneal abrasion/ulceration in horses undergoing general anaesthesia and contamination rate of ophthalmic solutions are similar to those previously reported in dogs.