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Trigeminal nerve-mediated head-shaking (TNMH) in horses is a diagnosis made by exclusion. Computed tomography (CT) is frequently used to identify any disease process that could cause the clinical signs of head-shaking. Although abnormalities are frequently identified, it is unknown whether treatment of these conditions improves clinical signs.To ascertain the clinical significance of CT findings in horses presented with a complaint of head-shaking.Retrospective case series.CT and patient records were reviewed and all abnormal findings and any treatments subsequently carried out was recorded. A questionnaire was sent to referring veterinarians and owners were contacted by telephone to establish whether treatment of the identified condition improved clinical signs.This study included 103 horses presented for head CT with the complaint of head-shaking with follow-up information obtained for 84 horses (81.6%). The diagnosis of TNMH was based on a combination of positive maxillary nerve block and/or response to treatment for TNMH. Although TNMH was the most common diagnosis with 62 horses (60.2%) affected, in 22 horses (21.4%), a primary disease process was identified and treatment of the condition eliminated signs of head-shaking. Clinically relevant primary diseases included dental fracture, primary sinusitis, temporo-mandibular joint arthritis, nuchal bursitis, musculoskeletal pathologies, basisphenoid fracture, otitis externa and a mass affecting the infra-orbital nerve.Some clinical information was missing and follow-up information was not obtained in all cases.CT was perceived as a useful diagnostic tool by most veterinarians, ruling out significant abnormalities. In over 20% of the cases, a treatable primary condition was identified leading to complete resolution of clinical signs.Las sacudidas de cabeza mediadas por el nervio Trigémino (TNMH) en caballos es un diagnostico por exclusión. La tomografía computarizada (CT) es frecuentemente utilizada para identificar cualquier proceso patológico que pudiese ser la causa de los síntomas de sacudida de cabeza. Aunque se identifican frecuentemente anomalías, no se sabe si es que el tratamiento de estas condiciones mejora los signos clínicos.Demostrar la significancia clínica de los hallazgos por CT en caballos presentados con queja de sacudida de cabeza. DISEÑO DEL ESTUDIO: Series de casos retrospectivos. MÉTODOS: Los archivos de tomografía computarizada y de pacientes fueron revisados y todos los hallazgos anormales y los tratamientos llevados a cabo subsecuentemente fueron anotados. Un cuestionario fue mandado a los veterinarios que difirieron los casos y los dueños fueron contactados por teléfono para saber si el tratamiento de la condición identificada mejoro los síntomas.Este estudio incluyo a 103 caballos presentados para CT de cabeza con queja de sacudida de cabeza con información subsecuente obtenida en 84 caballos (81.6%). TNMH fue el diagnostico basados en un combinación de bloque positivo del nervio maxilar y/o respuesta positiva a tratamiento de TNMH. Aunque TNMH fue el diagnostico mas común con 62 caballos (60.2%) afectados, en 22 caballos (21.4%), un proceso patológico primario fue identificado y el tratamiento de la condición elimino los síntomas de sacudida de cabeza. Las enfermedades clínicas primarias relevantes incluyeron fracturas dentales, sinusitis primaria, artritis de la articulación temporo-mandibular, bursitis nucal, patologías musculo esqueléticas, fracturas basifenoideas, otitis externa y masas tumorales afectando al nervio infra-orbital.No se pudo obtener toda la información clínica e no se obtuvo información de seguimiento en todos los casos.La tomografía computarizada era considerada como un herramienta diagnostica por la mayoría de los veterinarios, descartando anomalías significativas. En mas de un 20% de los casos, una condición primaria con tratamiento fue identificada y esta llevo a la resolución de los síntomas clínicos.

Background Blood l-lactate concentrations are higher in people with developing or established diabetes mellitus and insulin resistance. Objectives To investigate whether blood l-lactate concentrations are positively correlated with measures of insulin dysregulation (ID) or increased autumnal ACTH concentrations in ponies. Animals Systemically healthy client-owned ponies (n = 101). Methods Prospective case-control study. Blood samples were obtained from 101 clinically healthy ponies. Breed, weight, height, and subjective and objective measures of body condition were recorded. Blood l-lactate, glucose, triglyceride, total adiponectin, and ACTH concentrations were measured and an oral sugar test (OST) was carried out. Correlations between blood l-lactate and variables of endocrine health were determined. Results Using a seasonal cutoff point of ACTH concentrations ≥47 pg/mL, 55 ponies had increased autumnal ACTH concentrations and 45 did not. Using a basal insulin concentration of >50 μiU/mL, 42 ponies were diagnosed with ID and 58 were not. Using a 60 minutes after OST cutoff point of >45 μiU/mL, 57 ponies had ID and 37 did not. Blood l-lactate concentrations were significantly lower in obese (average body condition score ≥ 7/9) compared to nonobese ponies (0.6 mmol/L; range, 0.0-1.9 mmol/L vs 0.8 mmol/L; range, 0.3-2.7 mmol/L; P = .01). No other significant correlations were detected. No differences were detected between ponies with and without increased autumnal ACTH concentrations (0.7 mmol/L; range, 0.0-2.7 mmol/L vs 0.7 mmol/L; range, 0.3-1.8 mmol/L; P = .84) and with and without ID (0.7 mmol/L; range, 0.3-2.7 mmol/L vs 0.8 mmol/L; range, 0.0-1.6 mmol/L; P = .63). Conclusions and clinical importance Results do not support an effect of endocrine status on l-lactate concentrations in blood of ponies.

OBJECTIVE: Hyponatremia and rapid correction of hyponatremia can lead to neurological abnormalities. The objective of the study was to determine whether plasma sodium concentrations (Na⁺) and speed of correction of hyponatremia are significantly associated with neurological abnormalities in foals. DESIGN: Retrospective cohort study 2012 to 2016. SETTING: Equine hospital. ANIMALS: One hundred and nine foals

OBJECTIVES: A recent study described increased l‐lactate concentrations in ponies with gastrointestinal disease compared to horses, but blood glucose (BG) concentrations were not considered. The study tested the hypothesis that BG and l‐lactate concentrations are correlated in horses and ponies with gastrointestinal disease and that BG concentrations, not equid type (pony vs horse), are an independent predictor of L‐lactate concentrations. It was further hypothesized that equid type was an independent predictor of BG concentrations. DESIGN: Retrospective study 2008–2016. SETTING: University teaching hospital. ANIMALS: Admission data from 545 animals (384 horses and 161 ponies) with gastrointestinal disease. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Data collected included signalment, clinicopathological findings on admission, and nature and location of the gastrointestinal lesion (strangulating vs non‐strangulating and large vs small intestinal lesion). The association between admission blood l‐lactate concentrations, equid type (pony or horse) and BG concentrations was investigated in a multivariable model. Admission l‐lactate and BG concentrations were strongly correlated (n = 522; r = 0.63; P

A 9‐year‐old show pony mare became acutely lame following removal of a bone sequestrum of the distal phalanx of the right thoracic limb. The mare also suffered from ongoing right dorsal colitis secondary to previous long‐term nonsteroidal anti‐inflammatory drug (NSAID) use. To avoid further NSAID use, a protocol for caudal epidural administration of morphine and detomidine in an increased volume was used to provide analgesia to the thoracic limbs. A total volume of 50 mL (0.2 mL/kg bwt) was administered over approximately 90 s. Immediately following the injection, the pony collapsed into lateral recumbency and experienced an apparent generalised seizure characterised by loss of consciousness and frantic paddling of all four limbs. The pony recovered rapidly without intervention, and no residual neurological deficits were noted. The epidural analgesia resulted in a marked improvement in comfort levels. The speed of injection is thought to have caused a change in epidural and intracranial pressures resulting in a generalised seizure and highlights the importance of administering large volumes slowly.

Due to increasing antimicrobial resistance, pressure on veterinarians is mounting to adhere to responsible use of antimicrobial drugs. Antimicrobials are frequently included in the treatment of systemically ill horses due to the strong likelihood of an infection and the innate difficulties in differentiating systemic inflammation secondary to noninfectious from infectious causes. In light of increasing antimicrobial drug resistance and the potential negative impact of antimicrobials on equine patients, every attempt should be made to identify noninfectious disease, choose first‐line antimicrobials and discontinue treatment as soon as possible. In most cases, a short duration of antimicrobial therapy ranging from a single dose (e.g. preoperatively) to 24–72 h might be sufficient with long‐term treatment being rarely required. This article aims to provide practical guidelines for antimicrobial drug usage in critically ill adult horses by describing ancillary diagnostic aids that can help establishing whether or not an infection is present, discussing commonly encountered pathogens and their typical antimicrobial drug sensitivity patterns, and providing some guidance how to safely shorten the duration of antimicrobial therapy.

The glycocalyx, a gel-like layer covering the luminal surface of vascular endothelial cells has several key functions in maintaining homeostasis in the vasculature. Interest in the glycocalyx has significantly increased in the last decades and damage to this vital layer appears to influence progression and recovery in many disease processes. Pathological injury to the glycocalyx occurs in ischaemia–reperfusion, inflammation, sepsis, shock, burns and excessive shear stress. There is increasing evidence that iatrogenic interventions such as fluid therapy influence the integrity of the glycocalyx and can even worsen the initial injury from pathological events. Rapid infusion of crystalloids and colloids, hypervolaemia, hypernatraemia and hyperglycaemia have all been associated with increased glycocalyx shedding. Current treatment recommendations aim to minimise iatrogenic damage. In the future, interventions aimed at restoring glycocalyx integrity and function might become valuable tools in critical care.

Key Clinical Message A rhomboid blepharoplasty can be used to achieve functional and cosmetic eyelid reconstruction at the medial canthus in the horse. Combination of a rhomboid blepharoplasty with cryotherapy is a treatment option for eyelid ocular squamous cell carcinomas.

Treatment of severely ill horses often requires administration of antimicrobial drugs. Due to increasing antimicrobial drug resistance, their use should be considered on a case-by-case basis, choosing first-line antimicrobial drugs whenever feasible and discontinuing treatment as soon as the possible. In most cases, a short duration of antimicrobial therapy, ranging from a single dose (for example pre-operatively) to 24–72 hours, might be sufficient. Only rare exceptions require long-term treatment. The article aims to provide practical information about antimicrobial drug usage in sick horses, by describing ancillary diagnostic aids that can help establishing whether or not an infection is present; listing commonly encountered pathogens and their typical antimicrobial drug sensitivity patterns; and highlighting clinically important characteristics of antimicrobial drugs, such as volume of distribution, tissue penetration and side effects.

BackgroundVenous air embolism is a potentially life-threatening complication of IV catheter use in horses. Despite widespread anecdotal reports of their occurrence, few cases have been reported in the literature and the prognosis is currently unknown.Hypothesis / ObjectivesOur objective was to describe the surrounding circumstances, clinical signs, treatment, progression and outcome of venous air embolism in hospitalized horses.AnimalsThirty-two horses with acute onset of compatible clinical signs associated with IV catheter disconnection or damage.MethodsMulticenter retrospective study. Data extracted from clinical records included signalment, presenting complaint, catheter details, clinical signs, treatments and outcome. ResultsMost cases resulted from extension set disconnection occurring within approximately 24 hours after catheter placement. In fewer horses, extension set damage was cited as a cause. Common clinical signs included tachycardia, tachypnea, recumbency, muscle fasciculations and agitation, with abnormal behavior including kicking and flank biting. Less commonly, pathological arrhythmias or more severe neurologic signs, including blindness and seizures, were noted. Progression was unpredictable, with some affected horses developing delayed-onset neurologic signs. Mortality was 6/32 (19%), including 2 cases of sudden death and other horses euthanized because of persistent neurologic deficits. Negative outcomes were more common in horses with recorded blindness, sweating or recumbency, but blindness resolved in 5/8 affected horses. Conclusions and clinical importanceThe prognosis for resolution of clinical signs after air embolism is fair, but permanent neurologic deficits or pathologic cardiac arrhythmias can arise. Unpredictable progression warrants close monitoring. Systematic clinic-based surveillance could provide additional useful information to aid prevention.

A neurofibroma of granular cell subtype is described in a 7-year-old horse. The horse had a 3-month history of ataxia affecting the forelimbs and hindlimbs, suggesting a C1-C6 neuroanatomical localization. Post-mortem examination revealed an intradural mass arising from the right sixth cervical spinal nerve and compressing the spinal cord. Histologically, the mass was composed largely of wavy spindle cells (a mixture of Schwann cells, perineurial cells and fibroblasts) intimately associated with ropy collagen fibres. Approximately 25% of the spindle cells were swollen and contained densely-packed, eosinophilic and periodic acid-Schiff-positive cytoplasmic granules. Immunohistochemistry for S100 and glial fibrillary acidic protein antigens labelled a proportion of neoplastic cells, while the cytoplasmic granules were positive for S100 and neuron specific enolase. This is the first report of a neurofibroma with granular cell differentiation in an animal. Granular cell differentiation in other peripheral nerve sheath tumours of animals is briefly discussed.

Three horses presenting with colic signs to the Equine Referral Hospital at The Royal Veterinary College underwent general anaesthesia between September 2013 and November 2017 for emergency exploratory laparotomy. No obvious cause for the colic signs was identified in two horses, while a haemoperitoneum was identified in the third. All horses were euthanased within 12 hours of surgery due to deteriorating haemodynamic instability and/or intractable pain. Postmortem examination revealed an adrenal mass in each case, confirmed to be a pheochromocytoma on histopathology. In retrospect, each horse had some hallmark characteristics consistent with a functional pheochromocytoma, including hyperglycaemia and hyperlactataemia. Extremely high packed cell volume (PCV) (>65 per cent) was also identified in two horses, with a high-normal PCV found in the haemoperitoneum case. Perioperative haemodynamic instability was predominantly characterised by episodes of intermittent hypertension and tachycardia.

Background Serum bile acid concentrations (SBA) and a histopathological biopsy score [Equine Vet J 35 (2003) 534] are used prognostically in equine hepatic disease. Hypothesis Histopathologic features and scores, but not SBA, differ between survivors and nonsurvivors and correlate with histopathologic evidence of hepatic inflammation and fibrosis. Animals Retrospective study. Records (1999–2011) of horses with hepatic disease diagnosed by biopsy and with concurrent measurements of SBA. Methods Retrospective cohort study. Biopsies were examined for inflammatory cell infiltration including type and distribution, fibrosis, irreversible cytopathology affecting hepatocytes, hemosiderin, or other pigment deposition and bile duct proliferation. SBA, histopathological findings and a histological score [Equine Vet J 35 (2003) 534] were compared between short- (survival to discharge) and long-term (>6 months) survivors and correlations between SBA and histopathological findings investigated. Results Of 81 cases 90% survived short-term and 83% long-term. Short-term and long-term nonsurvival were associated with SBA (P = .009; P = .006), overall (P = .001; P = .002) and parenchymal (short-term only; P = .01) inflammation, portal and bridging fibrosis (all P 2 and, less so, SBA >20 μmol/L are specific but not sensitive indicators of nonsurvival.

Objective—To examine factors associated with short- and long-term prognosis for horses undergoing repeated celiotomy within 14 days after the first colic surgery. Design—Retrospective case series. Animals—95 horses that had undergone 2 celiotomies within a 14-day period between 2005 and 2013 at 3 equine referral hospitals. Procedures—Historical, clinical, and laboratory data were compared between horses that did not survive and horses that did survive to hospital discharge (short-term survival rate) and to > 3 and > 6 months after hospital discharge (long-term survival rates). Results—Strangulating small intestinal lesions were the most common finding during the first celiotomy (60/95 [63.2%]), and persistent gastric reflux was the most common reason for the second celiotomy (56/95 [58.9%]). Reasons for a second celiotomy were not associated with survival rate. For horses that had long-term follow-up, 22 of 92 (23.9%) survived > 6 months after hospital discharge. Two of 13 horses with intestinal resections during both surgeries survived to > 6 months after hospital discharge. Compared with horses not undergoing intestinal resection, significantly fewer horses requiring resection during 1 or both surgeries survived to hospital discharge and to > 3 and > 6 months after hospital discharge. Incisional infections occurred in 68.4% (26/38) of horses that survived to hospital discharge, and 31.6% (12/38) developed incisional hernias or dehiscence. Conclusions and Clinical Relevance—Results indicated that the prognosis for horses undergoing repeated celiotomy is guarded, and intestinal resection negatively affects the long-term survival rate.

Objective To discuss controversies surrounding antimicrobial use in critically ill horses. Data Sources PubMed searches from 1970-present for terms including, but not limited to: “horse,” “foal,” “antimicrobial,” “prophylaxis,” “infection,” “surgery,” “sepsis,” and “antimicrobial resistance.” Human Data Synthesis Increasing bacterial antimicrobial resistance has changed first-line antimicrobial choices and prompted shortening of the duration of prophylactic and therapeutic treatment. The need to decrease bacterial resistance development to critically important antimicrobials has been highlighted. Veterinary Data Synthesis Veterinary medicine has followed a similar trend but often without a high-level evidence. Common dilemmas include diseases in which the theoretically most effective drug is a reserved antimicrobial, the inability to differentiate infectious from noninfectious disease, the duration and necessity of prophylactic antimicrobials and use of antimicrobials in primary gastrointestinal disease. These problems are illustrated using examples of purulent infections, neonatal sepsis, colic surgery, and treatment of colitis. Although enrofloxacin, cephalosporins, and doxycycline, in contrast to gentamicin, reach therapeutic concentrations within the lungs of healthy horses, the first two should not be used as first line treatment due to their reserved status. Due to the high risk of bacterial sepsis, antimicrobial treatment remains indispensable in compromised neonatal foals but shortening the length of antimicrobial treatment might be prudent. One prospective randomized study demonstrated no difference between 3 and 5 days of perioperative antimicrobial treatment in colic surgery but shorter durations were not evaluated. High-level evidence to recommend antimicrobial treatment of adult horses with undifferentiated diarrhea does not exist. Conclusions Few evidence-based recommendations can be made. Commonly used antimicrobial combinations remain the mainstay for treating purulent infections. Antimicrobial treatment for compromised foals should not extend beyond recovery. Continuation of prophylactic antimicrobials >3 days is likely unnecessary after colic surgery; shorter durations might be equally effective. Antimicrobial prophylaxis in adult horses with diarrhea is unlikely to be beneficial.

Objectives To investigate whether acupuncture can alter gait in horses as assessed by objective and subjective parameters. Study design Prospective, randomized, singleblinded, crossover study. Animals Eight adult horses. Methods Horses were randomly assigned to a treatment (three acupuncture treatments in 8 days) or control group. Subjective and objective gait analyses were performed before and after each treatment and at 1, 3 and 7 days after the last treatment (time-points 1–9, respectively). Horses were assessed at the trot in a straight line on a hard surface and on the lunge on the left and right reins on a soft surface (conditions 1–3, respectively). After 12 weeks, groups were reversed. Objective gait analysis was performed using inertial sensors and subjective analysis by two board- certified surgeons who reviewed video-recordings. Each limb was assessed for lameness before and after treatment. Lameness and global scores were assigned using 4-point scales. Assessors were blinded to treatment status. The effects of treatment (yes/no), time (1–9) and horse under conditions 1 –3 were compared using a linear mixed-effects model and a generalized estimating equation. Results Treatment decreased hip hike difference under all conditions [condition 1: control, 6.3 ± 6.4 mm versus treatment, –0.2 ± 6.4 mm (p = 0.007); condition 2: control, 9.7 ± 7.8 mm versus treatment, 2.8 ± 7.8 mm ( p = 0.032); condition 3: control, 7.3 ± 6.3 mm versus treatment, –2.7 ± 6.4 mm ( p = 0.003)]. Other parameters also improved significantly under conditions 1 and 3. Based on subjective gait analysis, treatment decreased lameness [odds ratio (OR) 0.51, 95% confidence interval (CI) 0.34–0.78; p = 0.002] but not global (OR 0.53, 95% CI 0.24–1.10; p = 0.12) scores. Conclusions and clinical relevance Acupuncture can change horses' gaits to a degree appreciable by objective and subjective analyses.

SummaryReasons for performing study Acorn toxicity has been anecdotally reported to cause fatal colitis and colic in horses but reports in the scientific literature are sparse. Objectives This study reports the diagnosis, treatment, prognosis and outcome of 9 cases with suspected acorn toxicity admitted to 2 referral hospitals. Study design Retrospective case series. Methods Case records from 2004 to 2013 were reviewed. Horses were included in the study if they met 3 of 4 criteria: exposure to acorns; clinical and laboratory data suggesting alimentary or renal dysfunction; acorn husks in the faeces or gastrointestinal tract; and necropsy and histopathological findings consistent with acorn toxicity. Data collected included case history, clinical presentation, clinicopathological data, ultrasonographic findings, case progression, and necropsy and histopathological findings. Results Nine horses met the inclusion criteria. Five cases presenting with haemorrhagic diarrhoea deteriorated rapidly and were subjected to euthanasia or died. Four cases showed signs of colic with gas distension, displacement of the large colon and diarrhoea. Three of these (33%) survived with medical management, the fourth was subjected to euthanasia. Post mortem examination of 6 cases demonstrated submucosal oedema of the large intestine and caecum (n = 6), acute tubular nephrosis (n = 6), diffuse necrohaemorrhagic and ulcerative typhlocolitis and enteritis (n = 4), and small intestinal oedema (n = 3). Conclusions Acorn ingestion may be associated with typhylocolitis leading to diarrhoea, colic and acute renal tubular nephrosis. Recovery is possible in mildly affected cases; more severe cases show hypovolaemia, intractable pain, renal dysfunction and cardiovascular failure, and often succumb to the disease process. Disease is only seen in a small proportion of the population exposed to acorns and there seems to be an increased occurrence in certain years. Further investigation into factors predisposing to disease is required, but limiting exposure to acorns in the autumn seems prudent.

Summary Sepsis is a major cause of death in neonatal foals and, in recent years, significant progress in the understanding of the underlying pathophysiology has been made. To achieve a successful outcome, early diagnosis and treatment focusing on supporting vital functions and neutralising the effects of the causative organisms are essential. The pharmacokinetics of many drugs differ in neonatal foals and more information for appropriate dosing of antimicrobial and anti-inflammatory drugs for neonatal foals is now available to guide clinicians in choosing the best dosages. Prevention remains difficult and focuses on early recognition while prophylactic use of antimicrobials is discouraged.

Equine thoracic radiography is an important diagnostic tool for the evaluation of intrathoracic disease processes. Traditionally, the description of equine pulmonary radiographs has been based on the presence or absence of certain pulmonary patterns, namely bronchial, interstitial, alveolar and vascular patterns that are commonly used in other species. However, the use of these patterns is not always intuitive or suitable in horses and rarely helps in establishing a differential diagnosis for an individual case. This article sets out a simple, step-by-step approach for the evaluation of equine thoracic radiographs, which can be used to establish likely differential diagnoses. The assessment is based on the presence or absence and localisation of radiographic opacities that are easily recognised even by minimally trained observers. The article also describes radiographic technique in adult horses and foals, as well as discussing advantages and shortcomings of thoracic radiography.

Summary Platelet transfusions might be indicated in horses with thrombocytopenia. The need for a transfusion cannot be determined by platelet numbers alone, as primary or co-existing disease processes, platelet function and age of the recipient also need to be considered. In patients with no co-morbidities, relevant bleeding is uncommonly observed with platelet counts >10 x 109/l and a therapeutic approach with initiation of treatment when signs of bleeding are observed might be justified.

SummaryReasons for performing study Clinical impression suggested that pony and miniature breeds (collectively referred to as ponies) presenting to a referral hospital for investigation of gastrointestinal disease had higher blood lactate concentrations on admission than large breed horses. Objectives The study tested the hypothesis that ponies with gastrointestinal disease had higher blood lactate concentrations on admission than large breed horses with similar disease severity. Study design Retrospective case–control study. Methods Medical records from September 2006 to July 2011 were reviewed for ponies with a primary presenting complaint of gastrointestinal disease. Two larger breed horses with gastrointestinal disease were selected as controls for each case. Data collected included case details, historical and clinicopathological findings, diagnosis and outcome. Results Information was collected on 50 ponies and 100 horses. Ponies had higher mean ± s.d. respiratory rates (27 ± 13 vs. 21 ± 13 beats/min; P = 0.01) and rectal temperatures (37.9 ± 0.6 vs. 37.4 ± 0.6°C; P = 0.006) and a longer median duration of clinical signs prior to presentation (10 h [1–72 h] vs. 6 h [1–120]; P

Pneumocephalus is occasionally encountered in horses but poorly described in the literature. The study aimed to describe historical, clinical and diagnostic imaging findings and outcome in horses to increase the awareness and recognition of the condition amongst equine practitioners, allowing appropriate management of these cases. Cases of pneumocephalus from 4 participating institutions were identified and case details extracted from the medical records. Five cases of pneumocephalus were identified. Head trauma with suspected or confirmed fractures of the sinuses was the underlying cause in 4 cases, while the remaining horse was thought to have developed pneumocephalus secondary to sinusitis or trauma. Diagnosis was established radiographically in 4 cases and by computed tomography in a fifth. Gas was noted between the cranial vault and the brain, in the lateral ventricles, in the brain parenchyma and within the cranial cervical canal. The gas accumulation resolved gradually in all horses and did not appear independently to result in neurological compromise. Long-term outcome was available for 3 cases, 2 of which were ultimately subjected to euthanasia due to neurological deficits. Pneumocephalus is a possible consequence of head trauma or sinusitis in horses; although the finding is frequently incidental, it has the potential to develop into a life-threatening complication. Imaging the complete skull and cranial cervical spine is important to allow identification and appropriate management of these cases. The use of computed tomography enables easier identification and localisation of the gas accumulation within the central nervous system.

Summary Verminous myeloencephalitis is a rare, but predominately fatal, cause of neurological disease in horses. A 6-year-old mare was admitted to the Royal Veterinary College Equine Referral Hospital following acute onset of depression, central unilateral blindness and compromised vision in the opposite eye. Based on pronounced eosinophilic inflammation detected in the cerebrospinal fluid (CSF) and diagnostic imaging findings indicating a space-occupying lesion within the brain, a presumptive diagnosis of aberrant parasitic migration causing parasitic encephalitis was made. Treatment consisted of anti-inflammatories and high doses of an anthelmintic. The horse's condition improved, the neurological deficits and observed space-occupying lesion within the brain resolved completely and the mare returned to full work. To the authors’ knowledge, this is the first report describing complete recovery from suspected aberrant parasite migration in the CNS and will hopefully encourage treatment of suspected cases in the future.

Summary Pulmonary fibrosis is a devastating and often progressive condition leading to exercise intolerance and frequently the demise of the animal. Although uncommonly encountered in horses, the condition is intensely researched both in human medicine and animal models. Viral infections have long been suspected to play a part in the development of pulmonary fibrosis and neoplastic conditions in other species. In 2007, an association between equine herpesvirus 5 (EHV-5) infection and nodular pulmonary fibrosis in horses was suggested and the name equine multinodular pulmonary fibrosis (EMPF) was introduced. Recently, the presence of EHV-5 in equine lymphoma has also emerged. The case report by Schwarz et al. in this issue describes a horse suffering from concurrent T cell leukaemia and EMPF in association with EHV-5. This article summarises current knowledge about EMPF and EHV-5 infections in horses, recent developments in the understanding of pulmonary fibrosis in man and the proposed contribution of viral infections to pulmonary fibrosis and neoplastic conditions.

Summary Reasons for performing the study: Platelet-rich plasma (PRP) is increasingly used for treatment of orthopaedic injuries. However, the effects of different stimuli on the release pattern of regenerative and proinflammatory factors from equine platelets are largely unknown and an optimal treatment protocol remains to be established. Objectives: The aim of this study was to identify a stimulus that enhanced release of histopromotive factors (platelet-derived growth factor BB [PDGF] and transforming growth factor 1β[TGF]) without causing concurrent release of a proinflammatory mediator (CCL5). Methods: Washed platelets were prepared from 6 healthy ponies and release of growth factors and CCL5 measured using commercially available ELISAs for human proteins following incubation with or without thrombin, chitosan or equine recombinant tumour necrosis factor (erTNF) over 24 h and subsequently over 96 h. Additionally, noncoagulated samples were analysed. Results: Regardless of whether a stimulus was present or what stimulus was used, PDGF and TGF release was maximal by 0.5–1 h when clot formation took place and very little release was observed after 24 h. Growth factor release was minimal in noncoagulated samples. In contrast, CCL5 release was not associated with coagulation and appeared to persist for much longer. High concentrations of erTNF caused significantly greater release of CCL5 at 6 h than any other stimulus tested. Conclusions: Growth factor release from equine platelets is dependent on coagulation but independent of the initiating stimulus, and is accompanied by more sustained release of proinflammatory mediators. Potential relevance: Supernatants collected from coagulated platelets could be an alternative treatment to PRP.

Protein kinase C (PKC) is an important regulator of platelet activation and different isoenzymes can play positive and negative regulatory roles. The PKC isoenzymes expressed in equine platelets have not been documented but pharmacological inhibition has suggested a role for PKC delta (δ) in modulating responsiveness to platelet activating factor (PAF) ( Brooks et al., 2009 ). Here the PKC isoenzyme profile in equine platelets has been characterised and PKCδ activation by PAF investigated. Platelet lysates were probed by Western blotting using a panel of antibodies against individual PKC isoenzymes. PKCδ and eight other isoenzymes were identified, namely classical PKCs alpha (α), beta (β), (both βI and βII) and gamma (γ), the novel PKCs epsilon (ɛ), eta (η) and theta (θ) and atypical PKC zeta (ζ). Having shown PKCδ to be present, a method was developed to measure PAF-induced isoenzyme translocation by preparing cytosolic and membrane fractions from digitonin permeabilised platelets. Phorbol 12-myristate 13-acetate (PMA) was shown to cause translocation of PKCδ to the membrane within 5 s. PAF also caused PKCδ translocation although the response occurred more slowly; a significant, 7.6 ± 1.2 fold, increase in band density compared to unstimulated platelets was observed at 15 min; p = 0.036, n = 3. These data support a role for PKCδ in regulating PAF-induced functional responses in equine platelets.

Summary Reasons for performing the study: Intestinal hyperammonaemia (HA) has been infrequently reported in individual horses; however, there have been no studies describing clinical and laboratory data as well as short- and long-term outcome in a larger number of cases. Objectives: To describe clinical and laboratory data and short- and long-term outcome in a large group of horses with intestinal HA. Methods: Multi-centred, retrospective study; case records of horses with HA were reviewed and any horse with a clinical or post mortem diagnosis of intestinal HA was included. Hyperammonaemia was defined as a blood ammonium (NH4+) concentration ≥60 µmol/l and horses with a diagnosis of primary hepatic disease were excluded. Relevant data were recorded and, if appropriate, data from survivors were compared to nonsurvivors to identify potential prognostic indicators. Results: Thirty-six cases, 26 mature horses and 10 foals with intestinal HA were identified. Case histories included diarrhoea, colic and neurological signs and the most common clinical diagnosis was colitis and/or enteritis. The most common clinical and laboratory abnormalities included tachycardia, increased packed cell volume, hyperlactataemia and hyperglycaemia. Fourteen horses (39%) survived to discharge; NH4+ concentration on admission was the only parameter significantly associated with survival. All surviving horses and foals for which follow-up information was available recovered completely and returned to their intended use without further complications. Conclusions and potential relevance: Intestinal HA occurs in mature horses and foals and can be associated with severe clinical and laboratory abnormalities; further studies are required to investigate predisposing factors and delineate possible differences in aetiologies.

Summary This report describes the use of an autologous transfusion to temporarily improve the oxygen carrying capacity in a case of haemoabdomen. The horse required multiple blood transfusions but use of allogenic transfusions was hindered by a severe adverse reaction. The blood previously lost into the abdomen was drained and returned to the circulation without observed adverse effects. Autologous blood transfusion is a technique which can be used alone, or in addition to, allogenic blood transfusions in selected cases of acute blood loss in horses.

Background: Coagulopathies are common in horses with ischemic or inflammatory gastrointestinal (GI) disturbances. There is indirect evidence suggesting that early stages of these diseases are characterized by hypercoagulability (HC). Hypothesis/Objectives: HC, assessed via thromboelastography (TEG), is common in horses with ischemic or inflammatory GI diseases. The degree of HC is correlated with nonsurvival and thrombotic complications. Animals: Thirty client-owned horses with ischemic or inflammatory GI disease, 30 client-owned horses with nonischemic or inflammatory GI disease, and 30 healthy horses (control group). Methods: Prospective, observational clinical study. TEG profiles of 30 horses with ischemic or inflammatory GI disease were obtained on admission and 48 hours after admission, and these were compared with profiles from 30 horses with nonischemic or inflammatory GI disease and 30 healthy controls. Prothrombin time (PT), activated partial thromboplastin time (aPTT), antithrombin activity (AT), and D-Dimer concentrations were also determined in horses with GI disease. Results: Horses with ischemic or inflammatory GI disease had shorter R times compared with healthy horses (14.8 ± 8.3 versus 22.8 ± 12 minute; P= .011). However, changes were subtle and TEG profiles did not resembled those obtained from animals or humans presumed to be hypercoagulable. Although conventional coagulation testing supported the presence of HC (decreased AT and increased D-Dimer concentrations), TEG and coagulation abnormalities were rarely found in the same horses and the methods were not statistically related. Conclusions and Clinical Importance: There is evidence of HC in horses with GI disease but techniques for diagnoses require refinement.

Summary This report describes the unusual diagnosis of a retrobulbar syncytial meningioma in a 16-year-old Thoroughbred gelding. The horse initially presented with unilateral left sided exophthalmos and apparent blindness characterised by unilaterally absent menace and pupillary light responses. Magnetic resonance imaging (MRI) identified a well-defined soft tissue mass intimately associated with the opticnerve.BasedonthecharacteristicMRIappearance,a meningioma was suspected. The eye was enucleated under general anaesthesia and partial excision of the mass was achieved. Histopathology confirmed the diagnosis and the horse underwent a course of adjuvant radiotherapy. Twelve months following surgery the horse is back in work, no neurological abnormalities have been detected and follow-up computed tomographic imaging of the skull has revealed mild bone sclerosis with no remnants of the mass identified. eve_112 503..510