The influence of experimentally-induced endotoxaemia on clinical variables and markers of systemic inflammation in donkeys (Equus asinus)

Abstract

ABSTRACT:In view of the frequent involvement of endotoxins in the pathogenesis of equine diseases, the present study set out to gain preliminary insight into the challenge caused by lipopolysaccharide (LPS) exposure in donkeys and into the responses of animals to LPS challenge. To the best of our knowledge, this is the first study to determine the susceptibility and response of donkeys to LPS administration and the first to describe the extent to which donkeys can tolerate a state of endotoxaemia. For this purpose, 18 clinically healthy, native breed donkeys were randomly allocated into three groups of equal size. The first and second groups received E. coli O55:B5 endotoxin at a dose rate of 20 ng/kg (Low dose group), and 5.0 µg/kg (High dose group), respectively, after dilution in 500 ml of 0.9% normal saline, while the third group (Control) received 500 ml of 0.9% isotonic saline solution. Blood samples were drawn from each animal before exposure to LPS and hourly for 6 h subsequently to measure the circulating levels of inflammatory cytokines as well as the cellular response. All animals were clinically monitored throughout the study period. Following LPS exposure, donkeys in both treated groups had quite different temporal patterns of clinical manifestations. The high dose of LPS yielded a statistically significant (P < 0.001 and P < 0.001, respectively) increase in heart rate, and respiratory rate, as well as hypothermia and poor outcome compared with animals receiving the low dose. The severity of colic was, in general, mild in donkeys receiving the low dose of LPS, while the signs were overt in those receiving the high dose. Donkeys of both treated groups exhibited marked cellular alterations and up-regulation of tumour necrosis factor alpha, interleukin (IL)-12 and IL-10 with a marginal increase in the values of serum amyloid A compared with controls (P < 0.05). The results described herein demonstrate that donkeys can respond to even a physiological dose of E. coli O55:B5 endotoxin, while a high dose can elicit overt clinical alterations and marked inflammatory responses. Further studies with an extended follow-up time are needed to verify and generalise the obtained findings and to evaluate novel medications to minimise the deleterious consequences of endotoxaemia in equine patients.

Reference intervals of acute phase proteins in healthy Andalusian donkeys and response to experimentally induced endotoxemia

“…Although RIs for some APPs in donkeys showed wide ranges (Hp, Cp, AGP, and PCT), wide ranges also are observed in horses and other mammals 7,8,13 . When compared with previously reported studies in donkeys using the same technique, our SAA concentrations were lower, 17,18 although interbreed differences partially could be responsible for these differences 28 . Previously reported Hp and CRP concentrations in healthy donkeys using immunoassays would be contained within our proposed RIs 16,17 .…”

“…A similar early response has been reported previously in donkeys. 18,34 In LPS-challenged horses, using even higher doses, the increase in SAA concentrations was slower. 35,36 Although more rapid, the SAA response in donkeys was milder than reported in horses.…”

Comparative anti‐inflammatory effects of insulin and dexamethasone on cardiovascular biomarkers and antioxidants in miniature donkeys subjected to induced carbohydrate overload

“…Similar findings have been reported after induced endotoxaemia in other species including donkeys (El‐Ashker et al . 2017) and horses (Oikawa and Yamaoka 2003). Increased HR and RR can result from numerous causes such as pain, stress, fever and decreased arterial blood pressure.…”

“…CRF acts in the central nervous system to stimulate sympathetic noradrenergic outflow and inhibit parasympathetic nervous activity, resulting in increased HR and RR (Oikawa and Yamaoka 2003; El‐Ashker et al . 2017). In this study, HR was statistically lower in treatment groups, compared to control after 12 h (p < 0.05).…”

Blood Storage Conditions Affect Hematological Analysis in Samples From Healthy Donkeys and Donkeys With Experimentally-Induced Endotoxemia

“…In addition, some of the artifactual changes caused by deficient storage in humans and dogs, such as pseudoleukocytopenia or pseudotoxic changes, can mimic typical features of the systemic inflammatory response syndrome (SIRS) or endotoxemia, leading to erroneous diagnosis (19,20). Endotoxemia is assumed to be as common in donkeys as in horses (21), but little is known about the hematological response to this disturbance in this species (21,22).…”