Serum amyloid A concentration in postoperative colic horses and its association with postoperative complications

Abstract

Objective: To determine serum amyloid A (SAA) concentrations in the postoperative (PO) colic horse and its association with PO complications and infection. Study design: Prospective case series. Animals: Fifty-one horses after colic surgery. Methods: Blood samples from horses undergoing exploratory celiotomy were analyzed for quantitative SAA and fibrinogen concentrations and for neutrophil count at days 0, 1, 2, and 4-6 and at hospital discharge. Results: Complications developed in 35 (69%) horses and included PO colic (n = 13, 25%), PO reflux (n = 11, 22%), intravenous catheter (IVC) complications (n = 11, 22%), low-grade fever (n = 11, 22%); surgical site infection (SSI; n = 9, 18%), high-grade fever (n = 7, 14%), and diarrhea (n = 4, 8%). There was an association between day 2 SAA and PO colic (P = .004), diarrhea (P = .042), IVC complications (P = .008), and PO reflux (P = .008) as well as day 4-6 SAA and PO colic (P = .004) and diarrhea (P = .018). Discharge SAA concentration was associated with SSI (P = .001). Fibrinogen concentrations at days 4-6 and at discharge were associated with PO colic (P = .003), diarrhea (P = .004), IVC complications (P = .002), and PO reflux (P = .023). No differences were seen in SAA, fibrinogen, or neutrophils between horses with PO infection vs those with non-infection-associated complications. Conclusion: Serum amyloid A was markedly increased in the PO period in all horses but did not differ between PO infection and noninfection complications. The amount of inflammation associated with PO colic and colic surgery was high and may have affected the predictive value of SAA for early PO infection. Clinical significance: Although increases occurred earlier, measurement of SAA with a point-of-care analyzer may not be a more sensitive indicator of infection in the early PO colic horse than fibrinogen concentration. Serum amyloid A may help detect SSI in the late PO period.

Equine Inflammatory Markers in the Twenty-First Century

“…47 It is known that surgery itself, such as exploratory celiotomy for colic, causes an increase in APPs, including SAA. 43,[48][49][50] Compared with more minor surgical procedures, exploratory celiotomy causes a prolonged APR, with serum SAA concentrations increased from 48 to 96 hours after surgery (compared with 12-24 hours with minor procedures). 48,50,51 Horses with postoperative complications had a more pronounced increase in SAA (61.4-fold over baseline) and took longer to achieve peak values (96 hours) compared with horses without complications (29fold increase; peak at 48 hours).…”

“…50 Another prospective study assessing SAA and complications in postoperative colic patients found that the magnitude of SAA increase was greater at 48 hours and 4 to 6 days postsurgery in horses with versus those without complications. 49 The data are conflicting regarding the accuracy and utility of SAA for determining outcome and prognosis in horses with colic. One study 44 found no significant differences in SAA concentration between survivors and nonsurvivors, whereas another larger study 50 of horses undergoing exploratory celiotomy found that patients with increased SAA concentrations 5 days postoperatively were slightly less likely to survive to discharge (odds ratio, 0.97).…”

Serum amyloid A and plasma fibrinogen concentrations in horses following emergency exploratory celiotomy

“…Preoperative measurement of [SAA] and [fibrinogen] has proved useful in evaluating potential gastro‐intestinal lesions, requirements for surgery and prognosis . However, the value of following trends in [SAA] and [fibrinogen] after exploratory celiotomy has only been reported in small numbers of horses (18 horses , 51 horses ). In man, [SAA] can be used to compare post‐operative outcomes between different surgical procedures .…”

Highlights of recent clinically relevant papers

“…In this prospective case study, Maia Aitken and colleagues in the USA aimed to determine serum amyloid A (SAA) concentrations in the post‐operative (PO) colic horse and its association with PO complications and infection .…”