J. M. Senior

Retrospective study of the risk factors and prevalence of colic in horses after orthopaedic surgery

The records of 496 orthopaedic operations on 428 horses were reviewed to estimate the prevalence of, and identify the risk factors for, the development of colic in horses after surgery. Colic was defined as any recognised sign of abdominal pain that could not be attributed to a concurrent disease. Fourteen of the horses developed colic; eight of them were undiagnosed, three were classified as impactions, one as tympanic colic of the colon, one as incarceration of the small intestine in the epiploic foramen, and one as left dorsal displacement of the colon in the nephrosplenic space. Morphine was associated with a four-fold increased risk of colic compared with the use of no opioid or butorphanol, and out-of-hours surgery was also associated with an increased risk.

Plasma endotoxin in horses presented to an equine referral hospital: Correlation to selected clinical parameters and outcomes

REASONS FOR PERFORMING STUDY Endotoxaemia is frequently presumed on the basis of clinical signs in horses with colic. OBJECTIVE Measurements of plasma endotoxin (LPS) are rarely made in clinical cases and there is little information on the correlations between this variable, clinical variables and outcomes. OBJECTIVES To measure LPS levels in plasma of horses presented to the Philip Leverhulme Equine Hospital on admission and daily for up to 4 days and to relate LPS levels to selected clinical parameters, such as heart rate and packed cell volume, and outcomes. METHODS Blood samples were collected and stored at -20°C prior to assay of the plasma using a validated kinetic chromogenic Limulus amoebocyte lysate (LAL) assay. Clinical parameters and outcome variables were collected from hospital records. Associations were determined by Chi-squared test and logistic regression analysis. RESULTS Daily blood samples were collected from 234 horses. LPS was detected in 26.5% of the study population and in 29% of those horses presented for colic. Horses providing samples with detectable LPS were more likely to die whilst in the hospital than those that did not (P = 0.045). Horses presenting with colic were more likely to have detectable LPS in their plasma than noncolic cases (P = 0.037), although LPS was detected in the plasma of 8 out of 42 noncolic horses. A horse that did not meet the study definition of clinical endotoxaemia was 10 times less likely to provide a positive LPS sample (OR 0.10, 95% CI: 0.05-0.22). CONCLUSIONS The proportion of horses providing samples with detectable LPS was similar to other studies. POTENTIAL RELEVANCE LPS was detected in the minority of horses presented with colic. Increased levels of LPS positively correlated with packed cell volume and with risk of mortality in colic cases.

Post anaesthetic colic in horses: a preventable complication?

REASONS FOR PERFORMING STUDY There is little information on the prevalence of, and risk factors associated with, post anaesthetic colic (PAC) in horses undergoing nonabdominal operations. OBJECTIVES To undertake the first prospective study of prevalence of PAC and identify risk factors in its development in nonabdominal procedures. METHODS A multicentre prospective case-control study was conducted, on every horse undergoing anaesthesia for a nonabdominal procedure between April 2004 and June 2005. Colic cases were defined as any horse with recognised signs of abdominal pain within 72 h of general anaesthesia that could not be attributed to any concurrent disease. Five control horses per case were selected randomly from the study population at all hospitals. Multivariable logistic regression analysis was used to examine the relationship between predictor variables and the risk of developing PAC. RESULTS The estimated mean prevalence of PAC in the study population was 5.2% (95% CI, 2.8, 8.0). However, the prevalence of colic varied between each centre. The most commonly diagnosed cause of colic was impaction. Multivariable analyses showed that the centre involved and the type of surgery performed were associated with an increased risk of PAC. Preoperative food deprivation and the use of opioid drugs were confounding factors. CONCLUSIONS Prevalence of PAC varied significantly between the 4 hospitals studied; there may be hospital-related covariates that account for this. The type of surgery performed influenced the risk of PAC. POTENTIAL RELEVANCE Identifying the risk factors for PAC is a prerequisite for its prevention. This study indicates horses at increased risk of PAC that might benefit from a more critical evaluation of post anaesthetic gastrointestinal function and/or the provision of preventative measures. Further investigation is required to explain the variation in prevalence of PAC between centres.

Factors associated with survival to hospital discharge following endoscopic treatment for synovial sepsis in 214 horses

REASONS FOR PERFORMING STUDY To determine risk factors involved in survival to hospital discharge of cases of synovial sepsis. OBJECTIVES Investigate pre-, intra- and post operative factors involved in short-term survival of horses undergoing endoscopic treatment for synovial sepsis. STUDY DESIGN Retrospective case series. METHODS Clinical data were obtained for horses (>6 months old) undergoing endoscopic surgery as part of management for synovial sepsis over a 7-year period in a single hospital population. Descriptive data were generated for pre-, intra- and post operative variables. Multivariable logistic regression analysis was used to develop 3 models related to presurgical, surgical and post surgical stages of management with outcome defined as survival to hospital discharge. RESULTS Two hundred and fourteen horses were included. In Model 1 (preoperative variables), increased preoperative synovial fluid total protein (TP) was associated with nonsurvival (OR 0.88, 95% CI 0.83-0.94, P<0.001) whereas the presence of a wound on admission was associated with survival (OR 4.75, 95% CI 1.21-18.65, P = 0.02). Model 2 (intraoperative variables) revealed that factors associated with decreased survival were anaesthetic induction outside of normal working hours (OR 0.36, 95% CI 0.15-0.88 P = 0.02) and presence of moderate/severe synovial inflammation at surgery (OR 0.28, 95% CI 0.12-0.67, P = 0.004). Model 3 (post operative variables) showed that increased post operative synovial fluid TP (OR 0.94, 95% CI 0.90-0.98, P = 0.013) and undertaking more than one endoscopic surgery for treatment (OR 0.19, 95% CI 0.05-0.70, P = 0.005) were associated with nonsurvival. Cut-off values for predicting survival were 55-60 g/l for preoperative and 50-55 g/l for post operative TP measurements. CONCLUSIONS This study has identified factors associated with altered likelihood of survival to hospital discharge following endoscopic surgery for synovial sepsis. Prognosis for survival to hospital discharge can be based on evidence from this study at the key stages of management of horses with synovial sepsis.

Reported morbidities following 861 anaesthetics given at four equine hospitals

POSTANAESTHETIC morbidity prolongs convalescence, thus increasing costs to the client, and can lead to death. Most information available on postanaesthetic morbidity in horses relates to musculoskeletal disorders, such as postanaesthetic myopathy or fractures (Richey and others 1990, Young and Taylor 1993). More recently, the prevalence of postanaesthetic colic after non-abdominal procedures has been estimated retro spectively (Senior and others 2004, 2006, Andersen and others 2006). Information relating to other types of post-anaesthetic morbidity is scarce. This short communication describes a multi-centre prospective study conducted to esti-mate the prevalence of and identify risk factors for reported morbidities in horses undergoin g non-abdominal procedures at four equine hospitals in the

Suspected venous air embolism in a horse

A horse which had had a caecal impaction for 10 days was treated by means of an ileocaecostomy but failed to respond satisfactorily. Before a second laparotomy was performed it was observed to have dislodged the extension set from a jugular catheter and air was heard being sucked into the vein. It became very agitated but was anaesthetised again and the impaction was removed through an incision in the apex of the caecum. After recovering from the anaesthesia it developed severe signs of pruritus which subsided only after 12 hours. These signs were considered most likely to have resulted from a venous air embolism.

Comparison of the EPOC and i-STAT analysers for canine blood gas and electrolyte analysis

OBJECTIVES A prospective study to evaluate agreement and precision of a new point-of-care portable analyser, the EPOC analyser, compared with the i-STAT analyser in canine blood. METHODS Blood samples (68 venous and 32 arterial) were obtained from 63 client-owned dogs for clinical reasons and surplus blood was used to analyse agreement between the EPOC and i-STAT analysers. Precision of the EPOC analyser was also assessed by repeat analysis of 20 samples. Measured analytes included pH, partial pressures of carbon dioxide and oxygen and concentrations of sodium, potassium, ionised calcium, glucose and haematocrit. Haemoglobin, base excess, bicarbonate and saturation of haemoglobin with oxygen were calculated. RESULTS EPOC precision was acceptable, but agreement was poor for sodium, haematocrit, haemoglobin and base excess. Overall, method comparison was poor for pH, partial pressure of oxygen, sodium, haematocrit, haemoglobin and base excess. CLINICAL SIGNIFICANCE The EPOC analyser is useful for dogs, although clinically significant differences between the EPOC and i-STAT analysers exist for some analytes, and as such these analysers should not be used interchangeably.

Distribution of purinergic P2X receptors in the equine digit, cervical spinal cord and dorsal root ganglia

Purinergic pathways are considered important in pain transmission, and P2X receptors are a key part of this system which has received little attention in the horse. The aim of this study was to identify and characterise the distribution of P2X receptor subtypes in the equine digit and associated vasculature and nervous tissue, including peripheral nerves, dorsal root ganglia and cervical spinal cord, using PCR, Western blot analysis and immunohistochemistry. mRNA signal for most of the tested P2X receptor subunits (P2X1–5, 7) was detected in all sampled equine tissues, whereas P2X6 receptor subunit was predominantly expressed in the dorsal root ganglia and spinal cord. Western blot analysis validated the specificity of P2X1–3, 7 antibodies, and these were used in immunohistochemistry studies. P2X1–3, 7 receptor subunits were found in smooth muscle cells in the palmar digital artery and vein with the exception of the P2X3 subunit that was present only in the vein. However, endothelial cells in the palmar digital artery and vein were positive only for P2X2 and P2X3 receptor subunits. Neurons and nerve fibres in the peripheral and central nervous system were positive for P2X1–3 receptor subunits, whereas glial cells were positive for P2X7 and P2X1 and 2 receptor subunits. This previously unreported distribution of P2X subtypes may suggest important tissue specific roles in physiological and pathological processes.

Not small horses: improving treatments for donkeys

THERE are around 40 million donkeys in the world (FAO 2007) and more than 95 per cent of those are used for work, mainly as a means of transporting people or goods (Starkey and Starkey 1996). Apart from human labour, donkeys are the cheapest form of power (Pearson and others 1999) and have an important influence on the socioeconomic wellbeing of people in many developing countries. However, within such countries, donkeys often have a low status and can suffer from poor husbandry and treatment (Pearson and others 1999, Stringer and others 2011, Thiemann 2013). For example, one study in Ethiopia showed that back sores and wounds, often from poorly fitting tacks or excessive work, were the most common health problem in donkeys (Tesfaye and Curran 2005). There are multiple and complex reasons why donkeys may not receive optimal husbandry and veterinary care in developing countries, including cultural beliefs, lack of opportunity and poor education. From the veterinary treatment perspective, it would be desirable to have drugs, such as analgesics, available that we know to be effective in treating common health problems in donkeys. Before administering a therapeutic drug to an animal, we need to know that it will achieve …