Effect of season and geographic location in the United States on detection of potential enteric pathogens or toxin genes in horses ≥6-mo-old

Diagnostic approaches, aetiological agents and their associations with short-term survival and laminitis in horses with acute diarrhoea admitted to referral institutions

BACKGROUND

An international description of the diagnostic approaches used in different institutions to diagnose acute equine diarrhoea and the pathogens detected is lacking.

OBJECTIVES

To describe the diagnostic approach, aetiological agents, outcome, and development of laminitis for diarrhoeic horses worldwide.

STUDY DESIGN

Multicentre retrospective case series.

METHODS

Information from horses with acute diarrhoea presenting to participating institutions between 2016 and 2020, including diagnostic approaches, pathogens detected and their associations with outcomes, were compared between institutions or geographic regions.

RESULTS

One thousand four hundred and thirty-eight horses from 26 participating institutions from 4 continents were included. Overall, aetiological testing was limited (44% for Salmonella spp., 42% for Neorickettsia risticii [only North America], 40% for Clostridiodes difficile, and 29% for ECoV); however, 13% (81/633) of horses tested positive for Salmonella, 13% (35/262) for N. risticii, 9% (37/422) for ECoV, and 5% (27/578) for C. difficile. C. difficile positive cases had greater odds of non-survival than horses negative for C. difficile (OR: 2.69, 95%CI: 1.23-5.91). In addition, horses that were positive for N. risticii had greater odds of developing laminitis than negative horses (OR: 2.76, 95%CI: 1.12-6.81; p = 0.029).

MAIN LIMITATIONS

Due to the study's retrospective nature, there are missing data.

CONCLUSIONS

This study highlighted limited diagnostic investigations in cases of acute equine diarrhoea. Detection rates of pathogens are similar to previous reports. Non-survival and development of laminitis are related to certain detected pathogens.

Survival rates and factors associated with survival and laminitis of horses with acute diarrhoea admitted to referral institutions

BACKGROUND

Clinicopathological findings and their association with the outcome and development of laminitis in horses with acute diarrhoea has not been investigated in a multicentre study across different geographic regions.

OBJECTIVES

Describe and compare clinicopathologic findings of diarrhoeic horses between different geographic regions, survival rates and factors associated with non-survival and laminitis.

STUDY DESIGN

Multicentre retrospective case series.

METHODS

Information from horses with acute diarrhoea presenting to participating institutions between 2016 and 2020 was collected, and clinicopathological data were compared between surviving and non-surviving horses and horses that did and did not develop laminitis. Survival rates and seasonal and geographic differences were also investigated.

RESULTS

One thousand four hundred thirty-eight horses from 26 participating institutions from 4 continents were included; 76% survived to discharge with no differences identified between geographic regions. The survival proportion of horses with SIRS and creatinine concentrations > 159 μmol/L was 55% (154/279) compared with 81% (358/437) for those with SIRS and creatinine concentrations < 159 μmol/L (p < 0.001). The survival proportion of horses with SIRS that had an L-lactate concentration > 2.8 mmol/L was 59% (175/298) compared with 81% (240/296) in horses with SIRS and L-lactate concentration < 2.8 mmol/L (p < 0.001). The proportion of horses that developed laminitis was lower in Europe (4%, 19/479) compared with North America (8%, 52/619), Australia (8%, 12/138) and Latin America (11%, 16/146) (p < 0.05). More horses developed laminitis in the summer (46%, 39/85) compared with winter (18%, 15/85), spring (18%, 15/85) and fall (19%, 16/85) (p < 0.01). Horses with laminitis had greater odds of non-survival than those without laminitis (OR: 3.73, 95% CI: 2.47-5.65).

MAIN LIMITATIONS

Not all variables were available for all horses due to the retrospective nature.

CONCLUSIONS

Clinicopathological findings in horses with acute diarrhoea and their association with survival are similar across geographic regions. However, developing laminitis secondary to diarrhoea is less common in Europe. In addition, factors associated with non-survival were indicative of disease severity and subsequent cardiovascular compromise.

Relationship between the Cycle Threshold Value (Ct) of a Salmonella spp. qPCR Performed on Feces and Clinical Signs and Outcome in Horses

The objective of this retrospective study was to evaluate the clinical significance of fecal quantitative real-time polymerase chain reaction (qPCR) Salmonella results when taking the cycle threshold values (Ct) into account. The study included 120 Salmonella qPCR-positive fecal samples obtained from 88 hospitalized horses over a 2-year period. The mean Ct of the qPCR test was evaluated in regard to (1) clinical outcome and (2) systemic inflammatory response syndrome (SIRS) status (no SIRS, moderate SIRS, or severe SIRS) of the sampled horses. An ROC analysis was performed to establish the optimal cut-off Ct values associated with severe SIRS. The mean ± SD Ct value was significantly lower in samples (1) from horses with a fatal issue (27.87 ± 5.15 cycles) than in surviving horses (31.75 ± 3.60 cycles), and (2) from horses with severe SIRS (27.87 ± 2.78 cycles) than from horses with no (32.51 ± 3.59 cycles) or moderate (31.54 ± 3.02 cycles) SIRS. In the ROC analysis, the optimal cut-off value of Ct associated with a severe SIRS was 30.40 cycles, with an AUC value of 0.84 [95% confidence interval 0.76-0.91] and an OR of 0.64 [0.51-0.79]. Results suggest that including the Ct value in the interpretation of fecal qPCR results could improve the diagnostic value of this test for clinical salmonellosis in horses.

Acute diarrhea in horses: A multicenter Canadian retrospective study (2015 to 2019)

This study describes the clinicopathological findings, diagnostic approach, treatment, and factors associated with non-survival of diarrheic horses admitted to 4 Canadian university teaching hospitals between 2015 and 2019. A total of 300 horses, ≥1-year-old, with acute diarrhea were included and represented 1.6% (300/18 481; range: 0.7 to 3%) of admissions during that period, 70% of the horses survived to discharge. Testing for enteropathogens was limited to a single fecal culture for Salmonella spp. in most cases. An enteropathogen was identified in 14% (42/300) of the horses, but in the hospital with higher testing rates enteropathogens were detected in 29% (16/55) of cases. Neorickettsia risticii was the pathogen most frequently detected (31%, 32/102). Antimicrobial drugs and plasma were administered to 57 and 8% of the cases, respectively. Laminitis occurred in 24/298 (8%) of the horses. A multivariable regression model identified an association between non-survival of diarrheic horses and colic signs, increased heart rate, packed cell volume, creatinine concentration, and decreased total protein concentration. A standardized approach for pathogen detection in diarrheic horses is not consistent among Canadian veterinary teaching hospitals, and testing for known pathogens is limited. Signs of colic, severe dehydration, endotoxemia, and hypoproteinemia are associated with non-survival of diarrheic horses.