Retrospective evaluation of the effect of intravenous fluid administration on development of postoperative reflux in horses with colic (2004-2012): 194 horses

Retrospective evaluation of the effects of a single intraoperative dose of dexamethasone in horses undergoing exploratory laparotomy for small intestinal lesions (2008-2019): 240 cases

OBJECTIVE

To determine the effect of a single intraoperative dose of dexamethasone on the risk of postoperative reflux (POR) in horses undergoing small intestinal surgery and to investigate its association with incisional complications and short-term survival.

DESIGN

Retrospective cohort study over an 11-year period (2008-2019).

SETTING

UK-based private referral center.

ANIMALS

Two hundred and forty client-owned horses >6 months of age undergoing exploratory laparotomy for treatment of a small intestinal lesion.

INTERVENTIONS

Ninety-seven horses received a single intraoperative dose of dexamethasone (0.1 mg/kg, IV).

MEASUREMENTS AND MAIN RESULTS

Of 97 horses that received dexamethasone, 52 (53.6%) required small intestinal resection. Of 143 horses that did not receive dexamethasone, small intestinal resection was performed in 78 (54.5%). A total of 70 horses (29%) developed POR. There was no difference in the risk of POR between horses that received dexamethasone (25/97; 26%) and those that did not (45/143; 31%, P = 0.34). Risk factors associated with the development of POR included small intestinal resection (odds ratio [OR]: 4.55, 95% confidence interval [CI]: 2.27-9.11, P < 0.001), a PCV >40% 24 hours postoperatively (OR: 4.11, 95% CI: 2-8.45, P < 0.001), and a WBC count >10 × 109/L on admission (OR: 3.29, 95% CI: 1.47-7.41, P = 0.004). Dexamethasone was not associated with the odds of POR. Horses undergoing repeat laparotomy had a higher risk of incisional infection (OR: 8.07, 95% CI: 1.98-32.81, P = 0.004). Dexamethasone administration was not associated with incisional infection. The development of POR was negatively associated with short-term survival (OR: 0.07, 95% CI: 0.03-0.17, P ≤ 0.001). Dexamethasone administration was not retained in the final multivariable model for survival.

CONCLUSIONS

Intraoperative dexamethasone was not associated with the development of POR in this study population, nor did it have an effect on postoperative survival or incisional infection in horses undergoing surgical management of small intestinal disease.

Factors associated with development of post-operative reflux in horses with large colon volvulus and association with complications and outcomes

BACKGROUND

Post-operative reflux (POR) is rare following large colon volvulus (LCV) but does occur despite the absence of a small intestinal lesion. The prevalence, risk factors and association with survival of POR after LCV are currently unknown.

OBJECTIVES

To determine the prevalence of POR in horses with an LCV and its association with survival. A further objective was to assess factors which may predict POR. The hypothesis was that horses with POR following LCV surgery have a worse outcome for survival compared to those without POR.

STUDY DESIGN

A retrospective cross-sectional study.

METHODS

Clinical data of client owned horses which underwent colic surgery at a single UK referral hospital between 2008 and 2021, where LCV was the primary finding, were retrieved from hospital records. Statistical analyses included chi-squared, t-tests and odds ratios (ORs). Horses with concurrent lesions, and those that did not survive past anaesthetic recovery, were excluded from analysis. POR was defined as ≥2 L of gastric reflux on at least one occasion.

RESULTS

A total of 128 horses were included in the study, 23 of which had POR (18%). Overall survival to hospital discharge was 86%, 95% in the non-POR and 44% in the POR group. Horses with POR were less likely to survive to discharge than those without (OR = 26, 95% confidence interval [CI] [7.68-88.0], p < 0.001), and less likely to be alive 3 years after surgery (OR = 13.4, 95% CI [2.78-64.8], p < 0.001).

MAIN LIMITATIONS

Due to the retrospective study design, full data sets were not available for every case because clinical records were incomplete or, at that time, certain tests were not performed or clinical variables were not measured.

CONCLUSIONS

POR in LCV cases is a negative prognostic indicator for survival.

Comparison of liberal and goal-directed fluid therapy after small intestinal surgery for strangulating lesions in horses

BACKGROUND

There are few guidelines for the appropriate mode of fluid administration during and after colic surgery, and is challenging to reach the right balance while avoiding overhydration. This study aimed to compare goal-directed fluid therapy (GDFT) and 'liberal' fluid regimens (LFRs) in horses undergoing small intestinal surgery.

METHODS

Eighteen horses subjected to small intestinal surgery were matched according to the surgical lesion, type of anastomosis, length of resection, and duration of clinical signs. Horses in the LFR group were administered intravenous (IV) fluids for at least 24 h. In the GDFT group, IV fluids were administered only when considered necessary based on clinical parameters. Postoperative reflux (POR), packed cell volume, total protein, heart rate, venous lactate level, complications, and long-term survival rates were compared.

RESULTS

Three horses in the LFR and one in the GDFT group developed POR. Horses in the GDFT group had a shorter time interval to first oral water intake and shorter hospitalisation time. Postoperative complication rates and survival were not different between groups.

CONCLUSION

Further studies are necessary to set guidelines for the evaluation of hydration status and to plan postoperative fluid administration; however, GDFT may be a valid alternative to liberal fluid therapy after colic surgery.

Current Concepts in Fluid Therapy in Horses

Despite the frequent inclusion of fluid therapy in the treatment of many conditions in horses, there are limited studies available to provide evidenced-based, species-specific recommendations. Thus, equine fluid therapy is based on the application of physiology and extrapolation from evidence in other veterinary species and human medicine. The physiologic principles that underly the use of fluids in medicine are, at first glance, straightforward and simple to understand. However, in the past 20 years, multiple studies in human medicine have shown that creating recommendations based on theory in combination with experimental and/or small clinical studies does not consistently result in best practice. As a result, there are ongoing controversies in human medicine over fluid types, volumes, and routes of administration. For example, the use of 0.9% NaCl as the replacement fluid of choice is being questioned, and the theoretical benefits of colloids have not translated to clinical cases and negative effects are greater than predicted. In this review, the current body of equine research in fluid therapy will be reviewed, connections to the controversies in human medicine and other veterinary species will be explored and, where appropriate, recommendations for fluid therapy in the adult horse will be made based on the available evidence. This review is focused on the decisions surrounding developing a fluid plan involving crystalloids, synthetic colloids, and plasma.

Intraincisional medical grade honey decreases the prevalence of incisional infection in horses undergoing colic surgery: A prospective randomised controlled study

BACKGROUND

Medical grade honey has previously been described as a prophylactic treatment for wounds. Local prophylactic treatment may be valuable in preventing post-operative incisional infections in horses undergoing colic surgery but has not been evaluated.

OBJECTIVES

To establish whether medical grade honey gel, applied on the linea alba intraoperatively, decreases the prevalence of incisional infections in horses undergoing colic surgery with no associated adverse effects.

STUDY DESIGN

Prospective blinded randomised controlled clinical study.

METHODS

Horses older than 4 months that underwent colic surgery between May 2017 and December 2018 and survived for >2 weeks were included in the study. Horses were allocated 1:1 to treatment or control by block randomisation. In the treatment group, following closure of the linea alba, medical grade honey gel (L-Mesitran Soft^® ) was placed in the incision followed by apposition of subcutaneous tissue and skin. Information regarding the incision and post-operative complications was obtained at five time points (24 hours, 48 hours, 5 days, 14 days and 3 months).

RESULTS

Eighty-nine horses were included in the study. No adverse effects associated with treatment were observed. Horses in the treatment group had a lower rate of incisional infection compared with the control group (8.2% vs. 32.5%, P = .02). The protective effect of MGH had a calculated adjusted odds ratio (OR) of 0.2 (95% CI:0.07-0.8, P = .03). The number of patients required to receive treatment to prevent one case of incisional infection (NNEB) was 4.7. Risk factors associated with infection included: younger age (OR = 27, 95% CI: 2.3 to 306, P = .008) and diarrhoea 48 hours post-operatively (OR = 20, 95% CI: 1.5 to 277, P = .02).

MAIN LIMITATIONS

Follow-up was performed by different veterinary surgeons, hence not completely uniform.

CONCLUSION

Local prophylactic treatment with medical grade honey gel in the abdominal incision during surgery is safe and may significantly decrease the prevalence of incisional infections in horses undergoing colic surgery.