A study of leptospirosis in South African horses and associated risk factors.

Most leptospiral infections in horses are asymptomatic; however, acute disease manifestations as well as reproductive failure and recurrent uveitis have been reported. In South Africa, the epidemiology of the disease in horses is not well documented. A serosurvey to determine what serovars were present in horses from Gauteng, KwaZulu-Natal and Western Cape Provinces and to get an estimate of the seroprevalence of leptospirosis was carried out from January 2013 until April 2014 with the assistance of four large equine hospitals located in these provinces. Furthermore, associations between potential risk factors and both seropositive horses to the predominant serovar Bratislava and to Leptospira spp. were statistically evaluated using univariate analysis and multivariable logistic regression models. A total of 663 horse sera were collected and tested against a panel of 24 leptospiral serovars using the microscopic agglutination test. The most predominant serovars in Gauteng were Bratislava [32%, 95% CI: 29-35%]; Djasiman [10.4%, 95% CI: 8-12%] and Arborea [8.9%, 95% CI: 7-11%], in the Western Cape Province, Bratislava [27.35%, 95% CI: 23-32]; Djasiman [15.4%, 95% CI: 12-19%] and Arborea [14.5%, 95% CI: 11-18%] and in KwaZulu-Natal, Bratislava [39.4%, 95% CI: 34-44%]; Arborea [9.6%, 95% CI: 7-13%]; and Tarassovi [7.7%, 95% CI: 5-10%] respectively. Twenty one serovars representing 17 serogroups were detected with serovar Bratislava being the most serodominant. The apparent prevalence to one or more serovars of Leptospira spp. at a serum dilution of 1:100 in Gauteng, KwaZulu-Natal and Western Cape Provinces were 49%; 37% and 32% respectively. The true prevalence was calculated for each province taking into account the clustering effect during the sampling and was found to be between 24 and 74% in Gauteng; 26-39% in the Western Cape and 20-54% in KwaZulu-Natal. Nooitgedacht (South African horse breed) horses were found to be at greater risk of being seropositive to both serovar Bratislava (OR=5.08) and Leptospira spp. (OR=6.3). Similarly, horses residing on properties with forestry in the vicinity were found to be at greater risk of being seropositive to both serovar Bratislava (OR=9.3) and Leptospira spp. (OR=5.2). This study has shown that a high proportion of horses in South Africa are exposed to a wide range of serovars, inferring a complex epidemiology. It also describes for the first time new serovars of Leptospira in South African horses that have not previously been reported.

Exercise-induced pulmonary haemorrhage impairs racing performance in Thoroughbred racehorses.

REASONS FOR PERFORMING STUDY: Exercise-induced pulmonary haemorrhage (EIPH) occurs commonly in Thoroughbred racehorses worldwide. While EIPH is believed to be an important cause of impaired performance in these horses, there is limited evidence from sufficiently powered studies to evaluate this association. OBJECTIVES: To evaluate whether EIPH is associated with finishing position, distance finished behind race winners and differences in race earning among Thoroughbred horses racing in South Africa. STUDY DESIGN: Prospective cross-sectional study. METHODS: One thousand Thoroughbred horses racing in South Africa were enrolled prior to a single race and underwent tracheobronchoscopic examination within 2 h of racing. Three observers, blinded to the horses' identity and race performance, independently evaluated EIPH occurrence and severity using video recordings of the examination. Data were analysed using multivariable logistic and linear regression while controlling for important horse and race factors as potential confounding variables. RESULTS: Overall, 68% of horses had evidence of EIPH (grade ≥1). Horses without evidence of EIPH (severity grade 0), when compared with horses with any evidence of EIPH (grade ≥1), were >2 times more likely to win races (odds ratio = 2.3; 95% confidence interval 1.4-3.7; P = 0.001), finished an average of one length ahead of horses with EIPH (P = 0.03), and were 2.5 times more likely to be in the highest decile in race earnings (odds ratio = 2.5, 95% CI 1.5-4.1, P<0.001). However, no association was identified regarding finishing in the top 3 positions or earning money when analysed as a continuous variable or analysed as any winnings vs. none. CONCLUSIONS: Exercise-induced pulmonary haemorrhage was associated with impaired performance in Thoroughbred racehorses not medicated with furosemide and not using nasal dilator strips. These findings provide strong corroboration of previous research indicating that the occurrence of EIPH has a major impact on the ability of Thoroughbred racehorses to compete successfully as elite athletes.

Efficacy of a pectin-lecithin complex for treatment and prevention of gastric ulcers in horses.

The objective of this study was to evaluate the effect of a commercial feed supplement containing pectin-lecithin on squamous mucosa ulceration in horses exposed to an experimental ulceration model. Five mares were treated while five mares were controls for this crossover, blinded study. The mares were fed concentrates and hay and were stabled with a two-hour turn out per day for a period of four weeks. The pectin-lecithin complex was fed for the duration of the study on the treated group. At the end of a four-week period, all mares underwent a seven-day alternating feed deprivation (week 5). The study was repeated again after a four-week washout period. Gastroscopy was performed on days 1, 28 and 35 of the study and was digitally recorded. Independent evaluation of the recordings and scoring of the lesions using the Equine Gastric Ulcer Syndrome (EGUS), severity and number scores were performed by three experienced gastroscopists. The prevalence and severity of squamous ulcers significantly increased after intermittent feed deprivation (P<0.001). No significant effect of the treatment was observed (P>0.05). In this study, the addition of a commercially available pectin-lecithin complex to the feed of horses for five weeks did not prevent or minimise the risk for gastric ulceration of the squamous mucosa.

Coagulation, oncotic and haemodilutional effects of a third-generation hydroxyethyl starch (130/0.4) solution in horses.

REASONS FOR PERFORMING STUDY: Clinical indications for hydroxyethyl starches (HES) in horses include rapid plasma volume expansion and oncotic support during periods of hypoproteinaemia. Side effects such as coagulopathies associated with HES administration pose limitations to their use in veterinary medicine. In man, tetrastarch (130/0.4) has demonstrated less profound effects on coagulation compared with first- and second-generation HES. OBJECTIVES: To evaluate the haemostatic and oncotic effects of tetrastarch (130/0.4) administered at 10, 20 and 40 ml/kg bwt in healthy horses. STUDY DESIGN: Randomised crossover experiment. METHODS: Tetrastarch (130/0.4) was administered to 6 healthy pony mares at 10, 20 and 40 ml/kg bwt with a 2-week washout period. Packed cell volume, plasma total solids, colloid osmotic pressure (COP), platelet count and thromboelastography (TEG) were measured at baseline, immediately after infusion (0 h), and 1, 6, 12, 24, 48 and 96 h after tetrastarch infusion. RESULTS: All TEG variables remained within normal reference ranges in all 3 treatment groups. Administration of tetrastarch at 40 ml/kg bwt resulted in a prolonged K-time (P = 0.049) at 6 h post infusion, and decreased maximum amplitude at 0 (P<0.001), 1 (P = 0.022), 6 (P = 0.006), 24 (P<0.001) and 48 h (P = 0.013) post infusion compared with baseline. Administration of tetrastarch increased mean COP values above baseline in all 3 treatment groups, persisting to 24, 6 and 48 h for the 10, 20 and 40 ml/kg bwt doses, respectively. CONCLUSIONS: Although still within established reference ranges, compared with lower dosages, the administration of 40 ml/kg bwt tetrastarch (130/0.4) is more likely to induce changes in coagulation as measured by TEG. Tetrastarch increased COP at all dosages evaluated in healthy horses. Tetrastarch (130/0.4) at 10 and 20 ml/kg bwt has potential as a synthetic colloid for resuscitation and provision of oncotic support in horses.

Sequential L-lactate concentration in hospitalised equine neonates: A prospective multicentre study.

REASONS FOR PERFORMING STUDY: Evaluation of serial blood lactate concentrations [LAC] are of prognostic value for morbidity and mortality in critically ill human patients and neonatal foals, but have not been prospectively evaluated in a large multicentre study of critically ill neonatal foals. OBJECTIVES: To prospectively evaluate the prognostic value of sequential [LAC] analysis in critically ill neonatal foals with risk of mortality. STUDY DESIGN: Prospective, observational study. METHODS: Thirteen university and private equine referral hospitals enrolled 643 foals over the 2008 foaling season and [LAC] was measured at admission ([LAC]ADMIT ) and 24 ([LAC]24 ), 48 ([LAC]48 ), 72 ([LAC]72 ), 96 ([LAC]96 ) and 120 h ([LAC]120 ) after admission. [LAC] changes over time ([LAC]Δ) were calculated between sampling points. RESULTS: Nonsurvivors had significantly greater [LAC]ADMIT , [LAC]24 and [LAC]48 compared with surviving foals (P<0.001). In nonsurviving foals [LAC]Δ did not decrease over time while survivors showed significant positive [LAC]Δ between [LAC]ADM -24 and all other time periods (P<0.001). Logistic regression analysis showed that the odds of survival decreased for each 1 mmol/l [LAC] increase at all time points for all critically ill foals, independent of major final diagnoses as potential confounders. Septic foals had significantly greater [LAC] at all time points compared with nonseptic foals (P<0.001) and [LAC]Δ in septic foals was significantly more positive (suggesting better clearance of lactate from the blood) only at [LAC]ADM -24 and [LAC]72-96 (P<0.01), while in nonseptic foals [LAC]Δ was significantly positive between [LAC]ADM -24 compared with all other time periods (P<0.001). CONCLUSIONS: Blood lactate concentration is a strong, independent biomarker used to predict mortality in critically ill foals. Lactate metabolism is impaired in nonsurviving and septic foals and [LAC]Δ can be utilised to identify patients at high risk for mortality.

Phenotypic characteristics of hydrocephalus in stillborn Friesian foals.

Hydrocephalus is uncommon in horses. However, in recent years, it has become clear that the prevalence of hydrocephalus is greater in Friesian horses than in other breeds probably due to their limited gene pool. Before identification of candidate genes that predispose to the development of hydrocephalus in Friesian horses can be pursued, an in-depth, phenotypic, pathological description of the condition in Friesians would be of great benefit. Our study aimed to characterize the morphology of hydrocephalus in Friesian horses, to support further investigation of the genetic background of this condition. Four stillborn Friesian foals with hydrocephalus were examined macroscopically and microscopically and compared with 2 normal stillborn Friesian foals without hydrocephalus. In all clinical cases, tetraventricular and venous dilatations were observed, together with malformation of the petrosal bone and, as a result, narrowing of the jugular foramen. These observations suggest a communicative hydrocephalus with a diminished absorption of cerebrospinal fluid into the systemic circulation at the venous sinuses due to a distorted, nonfunctional jugular foramen. This type of hydrocephalus is also recognized in humans and dogs and has been linked genetically to chondrodysplasia; this has already been recognized in dwarfism, which is another monogenetic defect in Friesian horses.

Use of near-infrared spectroscopy to identify trends in regional cerebral oxygen saturation in horses.

REASONS FOR PERFORMING STUDY: Alterations in cerebral haemodynamics may contribute to perianaesthetic complications in horses. Near-infrared spectroscopy (NIRS) is frequently used intraoperatively in man to provide information regarding cerebral perfusion. OBJECTIVES: To determine whether NIRS can identify trends in regional cerebral oxygen saturation (rSO2) in horses and whether there is a correlation between rSO2 and venous oxygen tensions. METHODS: A cerebral oximeter sensor recorded rSO2 from the dorsal sagittal sinus of 6 healthy horses. Values for rSO2, arterial and venous oxygen and carbon dioxide tensions (PaO2, PvO2, PaCO2 and PvCO2 respectively), along with arteriovenous oxygen saturations (SavO2) were recorded in unsedated (recording period [RP] 1), sedated (RP2) and anaesthetised horses (RP3-5) and during recovery (RP6-8). During anaesthesia, horses were ventilated to achieve states of normo- (RP3), hyper- (RP4) and hypocapnoea (RP5). Data were evaluated descriptively and analysed using linear mixed-effects models and Pearson's correlation coefficient. RESULTS: Overall mean ± s.d. values for rSO2, PaO2, PvO2, PaCO2, SavO2 and mean arterial pressure varied significantly by RP (P<0.001). Significant decreases in rSO2 were identified between RP1 and the post anaesthetic periods (P<0.001). No significant differences in rSO2 values were identified between RP1 and the intra-anaesthesia periods or between RP3, RP4 and RP5. Significant correlations were identified between rSO2 and PaO2 (r = 0.448, P<0.001), rSO2 and PvO2 (r = 0.512, P<0.001) and rSO2 and SavO2 (r = 0.469, P<0.001). CONCLUSIONS: This is the first study to identify trends in rSO2 in horses using NIRS. A positive correlation was identified between rSO2 and PvO2, suggesting that alterations in cerebral oxygenation may be reflected in PvO2 . POTENTIAL RELEVANCE: Near-infrared spectroscopy may be used to monitor trends in rSO2 during equine anaesthesia. Decreasing rSO2 values may act as an early warning signal, alerting clinicians to potential cerebral desaturation events and indicating a need for intervention.

Association of admission L-lactate concentration in hospitalised equine neonates with presenting complaint, periparturient events, clinical diagnosis and outcome: a prospective multicentre study.

REASONS FOR PERFORMING THE STUDY: Admission L-lactate concentration is a useful and commonly measured biomarker not previously prospectively evaluated in a large multicentre study of critically ill neonatal foals. OBJECTIVES: To evaluate overall outcome and the association of survival and L-lactate concentration at admission ([LAC]ADMIT) by periparturient history, presenting complaint and clinicians' major diagnosis for ill neonatal foals. METHODS: Thirteen university and private equine referral hospitals enrolled 643 foals over the 2008 foaling season. Case details, historical, clinical and clinicopathological data were entered into standardised spreadsheets then unified for analysis. RESULTS: Overall survival was 79% (505/643). Risk of nonsurvival increased with each 1 mmol/l increase in [LAC]ADMIT (odds ratio 1.14, P < 0.001). Mean arterial pressure had a small (r2 = 19.1) but significant (P < 0.001) association with [LAC]ADMIT. Foals experiencing known dystocia or premature placental separation had increased [LAC]ADMIT (P < 0.001). Single umbilical problems (excluding uroperitoneum), meconium impaction only and failure of passive transfer of immunity only had 100% survival. Six clinicians' major diagnoses had increased odds of nonsurvival for each 1 mmol/l increase in [LAC]ADMIT: 'sepsis'; 'unspecified enterocolitis'; 'unspecified colic'; 'unspecified trauma'; 'immune related (not failure of passive transfer of immunity)' and 'respiratory only'. CONCLUSIONS AND POTENTIAL RELEVANCE: Survival of critically ill foals is good but varies with peripartum history, presenting complaint and clinicians' major diagnosis. L-lactate concentration at admission proves its utility as a valuable prognostic biomarker in neonatal foals and its utility appears to vary with peripartum history and clinicians' major diagnosis.

The impact of ultrasound during emergency after-hour admissions of horses.

Clinical use of diagnostic ultrasound at point-of-care or emergency situations, although common, has not been well documented in veterinary medicine. Medical records of after-hour emergency equine admissions during a 10-year period were reviewed and horses that received ultrasound scans were identified. Data sheets for each ultrasound scan performed during emergency clinical evaluation were collected and reviewed. Data extracted included anatomical region imaged, body system affected, documented ultrasonographic diagnosis and final diagnosis. Six hundred and nine records were available of which 108 horses had an ultrasound diagnostic procedure performed. The most common reason for emergency ultrasonography was to investigate gastrointestinal abnormalities, the largest proportion of these being large intestinal disorders. A complete ultrasound report was documented in 57% of evaluations, of which 79% correlated with a final diagnosis. Incomplete reporting made accurate interpretation of records difficult. Results indicate that the use of ultrasound in the emergency setting may be of diagnostic benefit and impact on patient management. Ultrasound training should be provided to residents in order to gain proficiency, especially with regard to the gastrointestinal system.

Prevalence of pharyngeal, laryngeal and tracheal disorders in thoroughbred racehorses, and effect on performance.

Endoscopic examinations were performed on 1005 thoroughbred racehorses in South Africa a mean (sd) 24 (12.3) minutes after racing, to determine the prevalence of pharyngeal, laryngeal and tracheal disorders, and to determine the relationship of these disorders with performance (number of wins and placed finishes). Overall, there was a low prevalence of grade 2 and 3 laryngeal function (LF) (2.2 per cent), grade 4 LF (0.6 per cent), epiglottic entrapment (1.3 per cent), subepiglottic cyst (0.2 per cent) and epiglottic deformity (0.6 per cent), while a higher prevalence of grade 2 to 4 pharyngeal lymphoid hyperplasia (PLH) (63 per cent), laryngeal debris (43.5 per cent), tracheal debris (21.9 per cent), tracheal mucus (99.5 per cent) and tracheal cartilaginous nodules (TCNs) (6.8 per cent) was observed. Performance was not affected by the presence of epiglottic deformity, grade 2 and 3 LF, grade 4 LF, debris within the trachea or larynx, or epiglottic entrapment. Grade 3 PLH occurred in younger racehorses; performance was impaired in horses with grade 2 and 3 PLH. Furthermore, TCNs were more prevalent in male racehorses and were associated with better performance.

Nuchal crest avulsion fracture in 2 horses: a cause of headshaking.

The medical records of 2 Thoroughbred horses that developed headshaking after blunt trauma to the occipital region are reviewed. The history, signalment, clinical signs, diagnostic methods, diagnosis and treatment were recorded in each case. Both horses displayed headshaking, while one horse repeatedly lifted its upper lip and pawed excessively at the ground. In both horses, diagnostic imaging of the occipital region revealed avulsion fragments of the nuchal crest and a nuchal desmitis in association with hyperfibrinogenaemia. The presence of an avulsion fragment of the nuchal crest with associated nuchal desmitis should be considered in horses presenting with headshaking and may respond favourably to conservative therapy.

Traumatic perforation of the trachea in two horses caused by orotracheal intubation.

Two of 348 horses that underwent gastrointestinal surgery under general anaesthesia developed perforations in their tracheas caused by the endotracheal tube. In one case the damage was probably caused when the horse was being moved from the induction room for surgery and excessive traction was exerted on the tube when the anaesthetic machine was moved too far ahead of the horse. The trachea of the other horse may have been damaged when it was intubated.

Perforation of the gastrointestinal tracts of four horses by metallic wires.

The medical records of four horses whose intestines had been perforated by metallic wires were reviewed. Three of the horses developed acute colic, and the other progressively lost weight and became inappetent and pyrexic. Metallic wires were detected either by exploratory laparotomy or postmortem examination. In three of the horses there were adhesions containing an encapsulated metallic wire in the small intestine, and in the other the wire was contained within an abscess with multiple adhesions involving the liver, spleen and mesentery.

After-hours equine emergency admissions at a university referral hospital (1998-2007): causes and interventions.

Medical records of equine after-hours admissions from 1998 to 2007 are reviewed. Data extracted from the medical records included signalment, reason for admission, pre-admission treatment, clinical presentation, procedures performed, final diagnoses, complications occurring in hospital, length of stay and outcome. Eight hundred and twenty after-hours admissions were available of which 75% were classified as emergencies. Most horses originated from Gauteng province (82%), with Thoroughbred, Arabian, and Warmbloods representing 46%, 10% and 7% of horses. Horses had a median age of 7 years and were predominantly male (60%). Gastrointestinal (64%) and musculoskeletal (19%) disorders were the primary reasons for admission. Anti-inflammatories, sedation and antibiotics were given in 51%, 20% and 15% of cases respectively prior to referral. On admission, 23% of horses had surgical intervention. Intravenous catheterisation (64%), rectal examination (61%), nasogastric intubation (56%), abdominocentesis (33%) and ultrasonography (19%) were the procedures performed most frequently. Surgical and medical colics constituted 28% and 27% respectively of the overall diagnoses, while piroplasmosis was diagnosed in 5% of horses. Post-admission complications occurred in <2% of horses. The median length of stay was 4 days (95% CI: 1 to 21 days). Overall survival to discharge was 74%. This study demonstrates that the majority of after-hours equine admissions to a university referral hospital required medical intervention and were mostly due to gastrointestinal disorders. Information obtained from this study can be used in emergency referral planning.

Causes of gastrointestinal colic at an equine referral hospital in South Africa (1998-2007).

The most common causes of gastrointestinal colic at an equine referral hospital in South Africa were determined following retrieval of the medical records of horses admitted during a 10-year study period. The study included 935 horses of which 28% were admitted after hours. Most horses were Thoroughbreds (54%), male (57%), with a mean age of 8.2 years and originated from the Gauteng Province (81%). Heart rate (98%), mucous membrane colour (95%) and auscultation of the abdomen (91%) were the clinical data commonly obtained at admission. Packed cell volume, total serum protein and white cell count were recorded in 78%, 75% and 44% of horses respectively. Transrectal palpation (93%), nasogastric intubation (84%), intravenous catheterisation (74%) and abdominocentesis (53%) were the most frequently performed procedures. Medical intervention was performed in 558 horses (60%). The common causes of medical colic were impactions (39%), tympany (7%) and displacement of the large colon (6%). An exploratory laparotomy was performed in 331 horses (36%). The common causes of surgical colic were displacement (29%), impaction (22%) and small intestinal strangulating lesions (18%). Death occurred in 3% of horses, while euthanasia before medical intervention was performed in 4%. Overall, medical intervention was successful in 93% of horses and 67% in horses managed surgically. In conclusion, 55% of all the equine admissions responded to medical intervention and the recovery rate for horses receiving both medical and surgical intervention was comparable to that reported in other studies.

Use of Ir192 interstitial brachytherapy for an equine malignant dermal schwannoma.

A 10-year-old Hanoverian mare was evaluated for a right buccal swelling that recurred 3 months following surgical resection. Ultrasonographic examination showed a broadly pedunculated subcutaneous mass at the level of 106-109 and 406-409 cheek teeth associated with an erosive mucosal lesion on the inside of the cheek. Histological examination of a biopsy specimen revealed a well-demarcated, malignant, dermal schwannoma. Following subcutaneous placement of platinum coated Ir192 wires under general anaesthesia, low-dose radiation of 5 gray per day was delivered for 14 days. Short-term complications included loss of patency of the right nasolacrimal duct, erythema, dermatitis, leukotrichia and left-sided deviation of the muzzle. Ten months later, there has been no tumour recurrence. Findings suggest that the use of interstitial brachytherapy should be considered for a malignant, dermal schwannoma that has recurred or is not amenable to surgery.

Acute lead intoxication in a pregnant mare.

Lead (Pb) intoxication in horses is usually a chronic phenomenon with clinical signs associated with central nervous dysfunction. This report gives details of a case of acute Pb intoxication in a 9-year-old American Saddlebred mare with severe, progressive and ultimately fatal neurological deterioration. During the 4 days of hospitalisation, clinical signs progressed from intermittent headshaking and depression to severe, continuous, uncontrollable manic behaviour. At autopsy, three grey-coloured, hard metal particles were present in the gastrointestinal tract and subsequently found to contain 2614 ppm Pb. Lead concentrations in the brain, liver, stomach and kidney were 29, 4, 6 and 2 ppm wet weight, respectively.

Admission clinicopathological data, length of stay, cost and mortality in an equine neonatal intensive care unit.

Veterinary internists need to prognosticate patients quickly and accurately in a neonatal intensive care unit (NICU). This may depend on laboratory data collected on admission, the cost of hospitalisation, length of stay (LOS) and mortality rate experienced in the NICU. Therefore, we conducted a retrospective study of 62 equine neonates admitted to a NICU of a private equine referral hospital to determine the prognostic value of venous clinicopathological data collected on admission before therapy, the cost of hospitalisation, LOS and mortality rate. The WBC count, total CO2 (TCO2) and alkaline phosphatase (ALP) were significantly higher (P < or = 0.05) and anion gap lower in survivors compared with nonsurvivors. A logistic regression model that included WBC count, hematocrit, albumin/globulin ratio, ALP, TCO2, potassium, sodium and lactate, was able to correctly predict mortality in 84% of cases. Only anion gap proved to be an independent predictor of neonatal mortality in this study. In the study population, the overall mortality rate was 34% with greatest mortality rates reported in the first 48 hours and again on day 6 of hospitalisation. Amongst the various clinical diagnoses, mortality was highest in foals after forced extraction during correction of dystocia. Median cost per day was higher for nonsurvivors while total cost was higher in survivors.

Tracheal perforation managed by temporary tracheostomy in a horse.

Tracheal trauma with resultant rupture is uncommonly reported in veterinary literature. We report the case of a 16-year-old Thoroughbred gelding that sustained a 1 cm longitudinal perforation of the dorsal tracheal membrane in the proximal cervical region. The horse subsequently developed dyspnoea due to acute upper respiratory obstruction secondary to severe emphysema of the guttural pouches. A temporary tracheostomy caudal to the site of tracheal perforation was performed under local anaesthesia. This procedure helped relieve the upper airway obstruction and aided resolution of the injury by diverting air away from the site of tracheal perforation. After conservative management, the gelding recovered completely.

Comparative biochemical analyses of venous blood and peritoneal fluid from horses with colic using a portable analyser and an in-house analyser.

Fifty-six horses with colic were examined over a period of three months. The concentrations of glucose, lactate, sodium, potassium and chloride, and the pH of samples of blood and peritoneal fluid, were determined with a portable clinical analyser and with an in-house analyser and the results were compared. Compared with the in-house analyser, the portable analyser gave higher pH values for blood and peritoneal fluid with greater variability in the alkaline range, and lower pH values in the acidic range, lower concentrations of glucose in the range below 8.3 mmol/l, and lower concentrations of lactate in venous blood in the range below 5 mmol/l and in peritoneal fluid in the range below 2 mmol/l, with less variability. On average, the portable analyser underestimated the concentrations of lactate and glucose in peritoneal fluid in comparison with the in-house analyser. Its measurements of the concentrations of sodium and chloride in peritoneal fluid had a higher bias and were more variable than the measurements in venous blood, and its measurements of potassium in venous blood and peritoneal fluid had a smaller bias and less variability than the measurements made with the in-house analyser.