Basic Postoperative Care of the Equine Colic Patient

The 3 time periods around colic surgery (preoperative, operative, and postoperative) are all critical to successful outcomes. Although much focus is often paid to the first 2 time periods, the importance of sound clinical judgment and rational decision-making in the postoperative period cannot be overstated. This article will outline the basic principles of monitoring, fluid therapy, antimicrobial therapy, analgesia, nutrition, and other therapeutics routinely used in patients following colic surgery. Discussions of the economics of colic surgery and expectations for normal return to function will also be included.

Salmonella in Horses

Managing Salmonella in equine populations can be challenging due to the epidemiology of this disease. In particular, due to the range of clinical outcomes, the occurrence of subclinical infections, and intermittent shedding. This greatly affects the ability to detect shedding and can lead to widespread environmental contamination and transmission. The veterinary profession can reduce the risk to stablemates and their caretakers, while meeting their ethical obligation, by appropriately managing these risks within animal populations and environments.

Prevalence of and risk factors associated with Salmonella shedding among equids presented to a veterinary teaching hospital for colic (2013-2018)

BACKGROUND

Gastrointestinal disease has been associated with shedding of Salmonella with previous studies demonstrating that horses with colic have a higher risk of acquiring and shedding Salmonella organisms.

OBJECTIVES

The purpose of this study was to determine the prevalence of and risk factors associated with Salmonella shedding in a colic population at a referral clinic.

STUDY DESIGN

Retrospective case-control study.

METHODS

For each colic case that was positive for Salmonella (n=56), two colic cases (n=112) that tested negative for Salmonella, were enrolled as controls. Associations between variables and Salmonella shedding were identified using logistic regression. Univariate and multivariable models were developed pertaining to 1) presenting clinicopathological data and 2) clinical variables that developed during hospitalisation.

RESULTS

Of the equids presenting with colic, 1585/1917 had a sample submitted for Salmonella testing. Of these, 56 were positive for Salmonella yielding a prevalence of 3.5%. Equids shedding Salmonella were more likely to present in July (OR=7.2, 95% CI=1.63-32.13, p=0.009) and present with a history of fever (OR=53.5; 95% CI=2.57-1113.03; p=0.01), increased lactate (OR=1.6; 95% CI=1.14-2.29; p=0.007) and/or neutropenia (OR=0.79; 95% CI=0.65-0.97; p=0.02). Hospitalised equids shedding Salmonella were more likely to be febrile (OR=4.8; 95% CI=1.47-15.8; p=0.01) and 10 times more likely to develop reflux (OR=10.1; 95% CI=1.67-61.43; p=0.01) compared to colic controls.

MAIN LIMITATIONS

Retrospective nature of the study and bias inherent to the retrieval of data from medicals records cannot be discounted. Classifying Salmonella status based on a single sample may have resulted in misclassification bias.

CONCLUSIONS

The prevalence of Salmonella shedding in this colic population was low compared to earlier reports. Certain predictors such as the development of a fever or reflux in hospitalised colic cases were associated with Salmonella shedding and may help the clinician to promptly identify horses likely to shed, thus helping institute effective use of barrier nursing precautions.

Potential infection of grazing cattle via contaminated water: a theoretical modelling approach

Wastewater discharge and agricultural activities may pose microbial risks to natural water sources. The impact of different sources can be assessed by water quality modelling. The aim of this study was to use hydrological and hydrodynamic models to illustrate the risk of exposing grazing animals to faecal pollutants in natural water sources, using three zoonotic faecal pathogens as model microbes and fictitious pastures in Sweden as examples. Microbial contamination by manure from fertilisation and grazing was modelled by use of a hydrological model (HYPE) and a hydrodynamic model (MIKE 3 FM), and microbial contamination from human wastewater was modelled by application of both models in a backwards process. The faecal pathogens Salmonella spp., verotoxin-producing Escherichia coli O157:H7 (VTEC) and Cryptosporidium parvum were chosen as model organisms. The pathogen loads on arable land and pastures were estimated based on pathogen concentration in cattle faeces, herd prevalence and within-herd prevalence. Contamination from human wastewater discharge was simulated by estimating the number of pathogens required from a fictitious wastewater discharge to reach a concentration high enough to cause infection in cattle using the points on the fictitious pastures as their primary source of drinking water. In the scenarios for pathogens from animal sources, none of the simulated concentrations of salmonella exceeded the concentrations needed to infect adult cattle. For VTEC, most of the simulated concentrations exceeded the concentration needed to infect calves. For C. parvum, all the simulated concentrations exceeded the concentration needed to infect calves. The pathogen loads needed at the release points for human wastewater to achieve infectious doses for cattle were mostly above the potential loads of salmonella and VTEC estimated to be present in a 24-h overflow from a medium-size Swedish wastewater treatment plant, while the required pathogen loads of C. parvum at the release points were below the potential loads of C. parvum in a 24-h wastewater overflow. Most estimates in this study assume a worst-case scenario. Controlling zoonotic infections at herd level prevents environmental contamination and subsequent human exposure. The potential for infection of grazing animals with faecal pathogens has implications for keeping animals on pastures with access to natural water sources. As the infectious dose for most pathogens is more easily reached for calves than for adult animals, and young calves are also the main shedders of C. parvum, keeping young calves on pastures adjacent to natural water sources is best avoided.

Managing Salmonella in equine populations

Infection control is achieved through all efforts used to prevent the introduction and limit the spread of contagious pathogens within a facility or population, with the goal of eliminating sources of potentially pathogenic microorganisms and to disrupt infectious disease transmission. Congregating animals from multiple sources, as occurs at veterinary hospitals, racetracks, equestrian events, and boarding and training facilities, increases the risk for transmission of infectious diseases such as salmonella. There is a recognizable standard of practice for infection control and due effort must be given to control and prevention of infectious disease transmission within animal populations and facilities.

Salmonella enterica serovar Oranienburg outbreak in a veterinary medical teaching hospital with evidence of nosocomial and on-farm transmission

Nosocomial salmonellosis continues to pose an important threat to veterinary medical teaching hospitals. The objectives of this study were to describe an outbreak of salmonellosis caused by Salmonella enterica serovar Oranienburg within our hospital and to highlight its unique features, which can be used to help mitigate or prevent nosocomial outbreaks in the future. We retrospectively analyzed data from patients that were fecal culture-positive for Salmonella Oranienburg between January 1, 2006, and June 1, 2011, including historical, clinical, and pulsed-field gel electrophoresis (PFGE) data. Salmonella Oranienburg was identified in 20 horses, five alpacas, and three cows during this time frame, with dates of admission spanning the period from August, 2006, through January, 2008. We consider most of these patients to have become infected through either nosocomial or on-farm transmission, as evidenced by molecular subtyping results and supportive epidemiologic data. Interpretation of PFGE results in this outbreak was challenging because of the identification of several closely related Salmonella Oranienburg subtypes. Furthermore, a high percentage of cases were fecal culture-positive for Salmonella Oranienburg within 24 h of admission. These patients initially appeared to represent new introductions of Salmonella into the hospital, but closer inspection of their medical records revealed epidemiologic links to the hospital following the index case. Cessation of this outbreak was observed following efforts to further heighten biosecurity efforts, with no known cases or positive environmental samples after January, 2008. This study demonstrates that a Salmonella-positive culture result within 24 h of admission does not exclude the hospital as the source of infection, and it underscores the important role played by veterinary medical teaching hospitals as nodes of Salmonella infection that can promote transmission outside of the hospital setting.

Identification of predictors of Salmonella shedding in adult horses presented for acute colic

BACKGROUND

Colic has been associated with shedding of Salmonella. Horses with salmonellosis typically develop diarrhea, fever, and leukopenia. Overlooking additional predictors may result in failure to detect shedding horses and increase environmental contamination.

OBJECTIVES

Evaluate associations between signalment and clinicopathologic data during early hospitalization and Salmonella shedding in horses treated for acute colic.

ANIMALS

Horses with acute colic admitted to a referral hospital. A total of 59 horses shedding Salmonella compared to 108 Salmonella-negative horses.

METHODS

Retrospective case-control study evaluating patient and Salmonella culture data. Associations between variables and Salmonella shedding were identified using logistic regression. Two multivariable models were developed pertaining to (1) information available within 24 hours of admission and (2) clinical findings that developed later during hospitalization.

RESULTS

Variables retained for multivariable model 1 indicated that Warmbloods and Arabians had increased odds for shedding Salmonella, as did horses requiring surgery (OR, 2.52; 95% CI, 1.10-5.75) or having more severe gastrointestinal disease (OR, 2.59; 95% CI, 1.08-6.20). Retained variables for model 2 demonstrated that horses that were treated surgically (OR, 1.60; 95% CI, 0.70-3.62), developed fever >103°F (OR, 2.70; 95% CI, 0.92-7.87), had abnormal leukocyte count (OR, 1.38; 95% CI, 0.61-3.09), or became inappetent and lethargic (OR, 16.69; 95% CI, 4.08-68.24) had increased odds for shedding Salmonella.

CONCLUSIONS AND CLINICAL IMPORTANCE

In horses with acute colic that present without signs of diarrhea, fever, or leukopenia, additional predictors associated with shedding Salmonella could be used to more promptly identify horses likely to shed organisms.