Ultrasonographically visible hepatic location in clinically normal horses.

OBJECTIVE: Ultrasound is widely used for evaluating horses with suspected liver dysfunction. Although a change in size is considered suggestive of pathology, no clear guidelines exist to define the hepatic ultrasonographically visible locations (HUVL) in horses. The aim of the study was to describe the HUVL in normal horses and determine whether this is altered by signalment, height, weight and body condition score (BCS). DESIGN: Prospective observational study. PROCEDURE: Bilateral ultrasonographic evaluation was performed in 58 clinically normal horses with no history of hepatic disease. The most cranial/caudal intercostal spaces (ICS), total number of ICS in which the liver was visualised and the ventral extent of the liver were recorded. RESULTS: Liver was visualised on the right in 56/58 horses (97%), the left in 41/58 (71%) and on both sides in 39/58 (67%). The most cranial ICS was 5 (right) or 4 (left) and the most caudal was 16 (right) or 11 (left). Liver was visualised in ICS 0-11 (right) and ICS 0-5 (left). Liver was not visualised ventral to the costochondral junction. There was no significant effect of sex, breed, height, weight or BCS on HUVL. Liver was visible in significantly fewer ICS on the right in horses aged 24 years and older (median ICS 3.5) compared with younger horses (median ICS 7; P = 0.016). CONCLUSION: These findings suggest that the liver should be consistently visualised on the right side, but absence of ultrasonographically visible liver on the left is unlikely to be clinically relevant. Liver dimensions may be decreased in older horses.

Trends in antimicrobial resistance in equine bacterial isolates: 1999-2012.

This study aimed to identify changing antimicrobial resistance patterns in isolates commonly obtained from equine clinical submissions. Laboratory records from 1999 to 2012 were searched for equine samples from which Escherichia coli or Streptococcus species was isolated. Susceptibility to enrofloxacin, ceftiofur, gentamicin, penicillin G, trimethoprim sulfamethoxazole (TMPS) and tetracyclines was noted. Isolates were divided into those identified between 1999 and 2004 (Early) and between 2007 and 2012 (Late). The proportion of isolates resistant to each antimicrobial and multiple drug-resistant (MDR) isolates (≥3 antimicrobial classes) was compared between time periods. There were 464 isolates identified (242 Early; 222 Late). A significant increase in the percentage of E coli isolates resistant to ceftiofur (7.3-22.7 per cent, P=0.002), gentamicin (28.5-53.9 per cent, P<0.001), tetracyclines (48.4-74.2 per cent, P=0.002) and MDR (26.6-49.4 per cent, P=0.007) was identified. There was a significant increase over time in the percentage of all streptococcal species resistant to enrofloxacin, ranging from 0 per cent (Early) up to 63 per cent (Late) depending on species. For Streptococcus zooepidemicus, resistance over time to tetracyclines and MDR increased. There was also a decrease in the proportion of S zooepidemicus resistant to TMPS over time. An increase in resistance over time of common equine pathogens to a number of commonly used antimicrobials supports the responsible use of antimicrobials.

Comparison of flunixin meglumine and meloxicam for post operative management of horses with strangulating small intestinal lesions.

REASONS FOR PERFORMING STUDY: Ex vivo evidence suggests that cyclo-oxygenase (COX) 2-preferential inhibitor nonsteroidal anti-inflammatory drugs (NSAIDs), such as meloxicam, have a less detrimental effect on intestinal healing than flunixin meglumine (FM). Whether this translates to a beneficial effect in horses with naturally occurring strangulating small intestinal (SSI) lesions is unknown. OBJECTIVES: To compare the clinical outcome of horses with naturally occurring SSI lesions treated with meloxicam or FM. STUDY DESIGN: Randomised prospective study. METHODS: Cases presenting to the Royal Veterinary College Equine Referral Hospital and Bell Equine Veterinary Clinic during 2010 and 2011 in which an SSI lesion was identified at exploratory laparotomy were eligible for inclusion. Horses received either 1.1 mg/kg bwt FM or 0.6 mg/kg bwt meloxicam i.v. q. 12 h. Clinical outcomes and clinical and laboratory parameters associated with endotoxaemia were compared between groups. RESULTS: Sixty cases were enrolled, 32 horses received FM and 28 received meloxicam. There was no difference in signalment, physical examination or surgical factors between groups. The overall survival to discharge was 81%; there was no difference in survival (P = 0.14) or incidence of post operative ileus (P = 0.25) between groups. There was no significant difference between the plasma lipopolysaccharide (LPS) concentrations at 0 h (P = 0.18) or 48 h (P = 0.60); however, there was a significant difference between neutrophil count at 48 h (P<0.05) and at 96 h (P<0.01) with significantly greater cell numbers in horses receiving meloxicam compared with FM. Blinded pain score evaluation showed that more horses receiving meloxicam showed gross signs of pain than those treated with FM (P = 0.04). CONCLUSIONS: Nonsteroidal anti-inflammatory drug choice did not affect major clinical outcomes in horses with SSI lesions but had some effects on signs of pain. This study provides no evidence to recommend one NSAID treatment above another based on survival or the incidence of ileus; however, evaluation of a larger number of cases is required.

Coagulation abnormalities and complications after percutaneous liver biopsy in horses.

BACKGROUND: Liver biopsy is useful in the diagnosis of liver disease in horses. However, bleeding is the major complication. Liver dysfunction can result in abnormalities in coagulation, although there is no definitive association between risk of hemorrhage after biopsy and coagulopathy in humans. Frequency of coagulopathies in horses with liver disease and the nature and frequency of complications after liver biopsy are not reported. HYPOTHESIS/OBJECTIVES: To determine whether there is an association between coagulopathy and hemorrhage after liver biopsy in horses. ANIMALS: Horses with suspected liver disease from which a liver biopsy had been obtained. METHODS: Retrospective study. Variables indicative of coagulation were recorded. The frequency and nature of complications after biopsy were assessed using clinical and hematologic data. The association between abnormal coagulation variables and complications was assessed. RESULTS: Seventy biopsies were obtained from 66 horses. At least 1 coagulation profile abnormality was identified in 58% of the 43 horses with histopathologically confirmed liver disease. Complications were observed in 4/32 monitored horses (33 biopsies). Three horses had a decrease in the packed cell volume suggestive of subclinical bleeding, and 1 horse developed a diaphragmatic hematoma. There was no association between coagulation profile abnormality and complications. CONCLUSION AND CLINICAL IMPORTANCE: Abnormalities of coagulation are common in horses with liver disease. Liver biopsy appears to be a safe procedure in the horse. An abnormal coagulation profile is not clearly associated with an increased risk of complications after biopsy.

Hepatic encephalopathy in a pregnant mare: identification of histopathological changes in the brain of a mare and fetus.

An 11-year-old Thoroughbred broodmare was evaluated for suspected hepatic dysfunction. Clinical signs of hepatic encephalopathy were evident at admission. Hepatic ultrasonographic evaluation revealed an increase in hepatic size, rounded borders and normal echogenicity. There was no evidence of cholelithiasis or bile duct distention. Increased activity of hepatic enzymes, increased bile acid and bilirubin concentration and an increased ammonia concentration were supportive of a diagnosis of hepatic disease and hepatic encephalopathy. Histopathological evaluation of a liver biopsy specimen was consistent with chronic active hepatitis. The mare was treated with intravenous fluids and antimicrobials, pentoxyfilline, branched-chain amino acids and dietary manipulation. Clinical improvement was observed initially; however, 3 weeks later, deterioration in the mare's condition necessitated euthanasia. Pathological lesions at necropsy were restricted to the liver and brain. The liver was diffusely firm with a prominent reticular pattern on the cut surface. A large choledocholith was present in the main bile duct of the left liver lobe. Histopathological examination of the liver revealed severe fibrosis, with hyperplastic bile ducts and mononuclear and neutrophilic inflammation. Pathological changes consistent with hepatic encephalopathy, (Alzheimer type II cells), were evident in the cerebrum of both the mare and the fetus.

Hypokalaemia as a cause of recumbency in an adult dairy cow.

A 3-year-old Holstein cow was presented for evaluation of recumbency. Physical examination and laboratory evaluations resulted in a diagnosis of hypokalaemia causing extreme skeletal muscle weakness. Treatment involved intravenous and oral potassium supplementation, antimicrobial and anti-inflammatory therapy, and management of recumbency using a flotation tank (the Aquacow Rise System). The cow recovered and returned to the milking herd. Multifactorial elements were identified as the cause of hypokalaemia including inappetance, treatments for ketosis and administration of dexamethasone.