Introduction
Pancreatitis is commonly encountered in people, dogs and cats, but the clinical presentation can vary from subclinical or mild nonspecific clinical signs to severe life-threatening disease (Mansfield 2012a). Acute and chronic forms are recognised, although these may occur concurrently. Understanding of the pathophysiology of acute pancreatitis is largely extrapolated from human clinical studies and experimental animal models (Bjørnkjær-Nielsen and Bjørnvad 2021). It is believed to result from the activation of trypsinogen and release of cathepsin-B and other pancreatic enzymes within acinar cells, leading to the activation of the apoptotic cascade inflammation, which is manifested by neutrophil migration to the pancreas as well as probable complement activation and a “cytokine storm” that further contributes to inflammation (Mansfield 2012b; Talukdar et al 2016).
Ante-mortem diagnosis of acute pancreatitis is difficult owing to the presence of nonspecific clinical signs and the lack of definitive diagnostic tests, including enzyme biomarkers (Johnson et al 2019). The biomarker ineffectiveness relates to low amylase activity of the equine pancreas (Harris and Gow 1892; Lorenzo-Figueras et al 2007), lack of tissue specificity of conventional lipase assays (Tietz and Shuey 1993) and instability of trypsin (Grulke et al 2003). In the absence of any one specific clinical sign or combination of signs that have been identified as pathognomonic for acute pancreatitis in dogs and cats (Xenoulis 2015), diagnosis is often based on a combination of clinical signs (such as anorexia, vomiting, weakness, and abdominal pain) and clinical pathology findings (Cridge et al 2021).
In most previously reported cases, the confirmation of pancreatitis in horses and donkeys has been established by post-mortem examination (Yamout et al 2012). The 1,2-o-dilauryl-rac-glycero-3-glutarate-(6′-methylresorufin) ester (DGGR) lipase assay has been shown to be specific for pancreatic lipase and has recently been validated for horses (Johnson et al 2019; Peters and Howard 2023). In the study by Johnson et al (2019) from Ireland, venous blood was collected and analysed for pancreatic (DGGR) lipase from 109 hospitalised horses (including 33 horses with various types of gastrointestinal disease, 22 of which had colic); 85% (28/33) of these horses had increased pancreatic lipase concentration. In another study from Switzerland (Lanz et al 2022), increased DGGR-lipase concentration above published reference limits was demonstrated in 30.2% of 192 horses with signs of colic, and was above 2x the upper reference limit (URL) in 15.6%. The median DGGR-lipase concentration in horses with large bowel displacement or torsion was significantly higher than the median concentration for horses with large bowel impaction, gastric impaction, dilation, or ulceration. DGGR-lipase concentration > 2x URL was significantly associated with surgical treatment, strangulating disease, and non-survival.
The aims of this study were to evaluate serum DGGR lipase concentrations in horses and donkeys presented to an equine hospital in the UK with gastrointestinal disease. The objectives were similar to a recently published study from Switzerland (Lanz et al 2022): to evaluate the prevalence of elevated DGGR lipase concentrations in horses presented for gastrointestinal disease, and to investigate any associations between DGGR lipase concentration at admission of cases to our hospital and the cause of colic, the outcome (survival or non-survival), and the treatment type (medical or surgical).