VN June 2023

Vetnews | Junie 2023 7 cardiovascular shock (Southwood et al., 2012), which might be worth noting as horses that fell into this category appeared to be quite affected by it in this study. Horses presenting with a “shock” heart rate on initial assessment were 10-13% less likely to survive medical treatment, 6-10% less likely to survive surgical treatment and >5 times more likely to be euthanised on initial assessment compared to the other heart rate categories of “plain tachycardia” (HR 49-69 bpm), normal and bradycardic (p = 0.006) Tachycardia in colic can be multi-factorial with dehydration, sepsis, or severe pain being important factors. Prevention of horses reaching the “shock” state is important in helping them survive a severe colic episode, highlighting the importance of early referral and aggressive fluid treatment. Other international studies are consistent with the findings (Ihler et al., 2004, Kos et al., 2022) Packed Cell Volume (PCV) may also be a potential prognostic indicator. Horses with increased PCVs (>50) have a surgical survival rate 2-3 times lower than those with a normal (30-50%) or low (<30%) PCV. Interestingly, a lower PCV was associated with a higher surgical survival rate in this study. This result suggests that the correction of dehydration may be more crucial than previously thought in horses undergoing colic surgery. However, this is still an ongoing investigation, and findings should be interpreted cautiously. In the medical cases, an increased PCV led to a 20% drop in the survival rate compared to those with normal and low PCVs (72% vs 91 & 92%) (p = 0.023). Other papers have also found similar associations with PCV in medical and surgical cases (Ihler et al., 2004, Kos et al., 2022, Hoaglund et al., 2018) The most common pathologies that received surgical treatment were impactions (n=52), displacements (n=31), torsion (n=13), strangulations (n=4), epiploic foramen entrapment (n=4), herniation (n=4), tympany (n=4) and volvulus (n=4). Several horses were diagnosed with multiple abnormalities. Medical pathologies were not analysed in the INCISE database and thus were not covered in this research paper. The number of impactions may have been skewed due to an increased number of Small colon impactions in June/July 2021, when the average monthly colic cases doubled to 60 horses in one month. The cause behind this is still under investigation. It is also worth remembering that Impactions are often not a primary issue and can be secondary to other lesions, occurring as a co-morbidity. When reviewing the complications recorded, the incidence of postoperative thrombophlebitis was higher than international findings (20% vs 1,3-18%) (Salem et al., 2016, Lankveld et al., 2001). One must be aware that colic and diarrhoea lead to chemical changes within the vasculature that make the jugular prone to inflammation and place the horse in a hypercoagulable state. Although students place most venous catheters at OVAH, this is done under close supervision by a clinician or an experienced veterinary nurse with thorough adherence to sterility and best practice guidelines. The catheter material used during the study period (EquiVet HiFlow LongTerm IV Catheter 12G/5,25 inch; made from polyurethane with suture wings) is considered to be the least likely type to induce thrombophlebitis (Lankveld et al., 2001). Catheters are also regularly flushed with a heparin-saline admixture 4-6 hourly. Therefore, it is likely that the increased incidence of thrombophlebitis was related to horses’ endotoxaemic/proinflammatory state rather than any issues related to catheter placement. The incidence of postoperative ileus was also slightly higher than previous findings (50,7% vs 10-47%) (Blikslager et al., 1994, Freeman et al., 2010, French et al., 2002, Morton and Blikslager, 2002, Mair and Smith, 2005a) but not substantially so. The information required to investigate factors contributing to ileus ( surgical time, surgical technique, grading of inflammation etc.) was not available for analysis in this study. In the period analysed, there was a wound infection of 25,3 %, which is lower than the international reports of a rate between 32-36%. The rate of surgical site dehiscence was 5.3, which compares similarly against international findings of 3-5%. (Mair and Smith, 2005b) A couple uncommonly associated postoperative conditions piqued the researcher’s interest: pneumonia and laminitis. Only one other study looked at pneumonia in the postoperative period of colic, and the underlying cause for pneumonia was not investigated; aspiration, nosocomial infections or opportunistic infections are possible causes. (Freeman et al., 2012) Further research is required to investigate this in the future. No results from studies investigating the incidence of laminitis and its relation to colic surgery or just colic itself are available. However, the endotoxaemic state a horse enters after surgery is generally regarded as a major risk factor for the development of laminitis. Previous studies investigated the use of LowMolecular Weight Heparin as laminitis prophylaxis after colic surgery, but the results are contradictory. (De La Rebière de Pouyade et al., 2009, Feige et al., 2003) Some of the limitations of this study are inherent to its retrospective nature.: Some of the data that the INCISE project aimed to collect, such as anaesthetic and surgical durations, can not be evaluated as the information was not always available on the hospital records and not all data was available for all horses. The study also did not aim to evaluate the duration of hospitalisation or the skill/experience of the surgeon that influenced the outcome of horses treated for colic. Additionally, the data was number of horses was small and collected over 33 months, with a majority of the cases coinciding with the height of the COVID-19 pandemic. Due to the pandemic, owners might have been under more financial duress than usual, which could have led to delayed referrals and increased motivation for euthanasia based on economic reasons. Leading Article >>> 8