Biomarkers of Inflammation in Exotic Pets

Coagulation Disorders, Testing, and Treatment in Exotic Animal Critical Care

Despite poor recognition in the literature, exotic companion animals are affected by many diseases that can result in disordered coagulation and fibrinolysis. This article outlines current knowledge of hemostasis, common diagnostic tests and reviews reported diseases associated with coagulopathy in small mammals, bird and reptiles. A range of conditions affect platelets and thrombocytes, endothelium and blood vessels, and plasma clotting factors. Improved recognition and monitoring of hemostatic disorders will enable targeted therapy and improved case outcomes.

Reference Intervals and Clinical Utility of Acute Phase Proteins and Serum Proteins Electrophoresis in the Hamadryas Baboon (Papio hamadryas)

Measurements of specific acute phase proteins (APP) and protein electrophoresis (EPH) fractions have been widely used to better assess the health of species under managed care across numerous taxa. To date, APP assays have not been validated in the hamadryas baboon (Papio hamadryas), and reference intervals have not yet been established. This information is critical for the interpretation of APP and EPH measurements used in the diagnosis of inflammatory diseases during routine veterinary care of this species. To obtain this information, banked serum samples from hamadryas baboons of various age, sex, and health status, under managed care at the North Carolina Zoo, were analyzed. A small pilot study found significantly higher serum amyloid A (SAA) and C-reactive protein (CRP) but not haptoglobin in baboons with acute inflammation compared to healthy counterparts, so these two APPs were investigated further. Reagents for serum amyloid A (SAA) and C-reactive protein (CRP) were validated, although differences in CRP reagents were observed. Based on the results of this study, SAA and CRP were defined as major APPs that were significantly increased in baboons with active inflammation or infection compared to healthy conspecifics. Baboons with acute inflammation additionally had significantly higher gamma globulins compared to healthy baboons. Although mean albumin concentrations were lower in baboons with acute inflammation, the difference from healthy baboons was not statistically significant. This study identifies SAA, CRP, and EPH as useful tools in the diagnosis of inflammatory disease in the hamadryas baboon and establishes reference intervals to aid in the future veterinary care of this species.

Acute phase reactants in nondomesticated mammals-A veterinary clinical pathology perspective

Applications for acute phase reactants (APRs) in nondomesticated mammals include identifying inflammatory disease, monitoring the course of specific disease processes and recovery during rehabilitation, detecting preclinical or subclinical disease, being used as bioindicators for monitoring population and ecosystem health, and as markers of stress and animal welfare. Serum amyloid A, haptoglobin, C-reactive protein, fibrinogen, albumin, and iron are most commonly measured. The procedure for evaluating an APR in a nondomesticated mammalian species should follow a stepwise approach beginning with an assessment of analytical performance, followed by an evaluation of overlap performance, clinical performance, and impact on patient outcomes and management. The lack of species-specific standards and antibodies for nondomesticated mammals presents a challenge, and more attention needs to be focused on assessing cross-reactivity and ensuring adequate analytical performance of APR assays. Sample selection for the initial evaluation of APRs should consider preanalytical influences and should originate from animals with confirmed inflammatory disease and healthy animals. Reference intervals should be generated according to published guidelines. Further evaluation should focus on assessing the diagnostic utility of APRs in specific disease scenarios relevant to a species. Greater attention should be paid to assay performance and uniformity of methods when using APRs for population and ecosystem surveillance. Veterinary clinical pathologists should work closely with zoo veterinarians and wildlife researchers to optimize the accuracy and utility of APR measurements in these various conservation medicine scenarios.

Biomarkers of Intestinal Injury in Colic

Biomarkers are typically proteins, enzymes, or other molecular changes that are elevated or decreased in body fluids during the course of inflammation or disease. Biomarkers pose an extremely attractive tool for establishing diagnoses and prognoses of equine gastrointestinal colic, one of the most prevalent causes of morbidity and mortality in horses. This topic has received increasing attention because early diagnosis of some forms of severe colic, such as intestinal ischemia, would create opportunities for rapid interventions that would likely improve case outcomes. This review explores biomarkers currently used in equine medicine for colic, including acute phase proteins, proinflammatory cytokines, markers of endotoxemia, and tissue injury metabolites. To date, no single biomarker has been identified that is perfectly sensitive and specific for intestinal ischemia; however, L-lactate has been proven to be a very functional and highly utilized diagnostic tool. However, further exploration of other biomarkers discussed in this review may provide the key to accelerated identification, intervention, and better outcomes for horses suffering from severe colic.

Avian Inflammatory Markers

Inflammation represents a fundamental response to diverse diseases ranging from trauma and infection to immune-mediated disease and neoplasia. As such, inflammation can be a nonspecific finding but is valuable as an indicator of pathology that can itself lead to disease if left unchecked. This article focuses on inflammatory biomarkers that are available and clinically useful in avian species. Inflammatory biomarkers are identified via evaluation of whole blood and plasma and can be divided into acute and chronic, with varying degrees of specificity and sensitivity. Evaluation of multiple biomarkers may be necessary to identify subclinical disease.

Advances in Exotic Animal Clinical Pathology

Over the last 10 years, exotic animal clinical pathology has been evolving, improving health assessment in avian, mammal, fish, reptile, and amphibian patients. These advances are reviewed in this article. Species-specific reference intervals for blood parameters are becoming more available (eg, for ionized calcium, endocrine panels, and vitamin D plasmatic concentrations). In addition, new technologies are being developed to facilitate targeted metabolite detection and result acquisition by veterinarians. Novel techniques, biomarkers, and clinical changes related to disease have been described in avian, mammal, fish, reptile and amphibian species. The use of mobile applications may also be helpful.

Evaluation of cardiac troponin I in serum and myocardium of rabbits with experimentally induced polymicrobial sepsis

Sepsis is a potentially life-threatening condition, and it is frequently complicated by myocardial damage. Data on myocardial damage in rabbit caecal ligation and puncture (CLP) models are limited, although numerous animal models have been used to study sepsis-associated myocardial damage. This study aimed to investigate the effect of CLP on cardiac muscle by measuring serum cardiac troponin I (cTnI) concentrations and by detecting both histopathological changes and cTnI immunoreactivity in cardiomyocytes in rabbits. After CLP was performed in rabbits, blood samples were taken from the jugular vein at 0, 4, 8, and 12 h for haematological and biochemical analyses. At the end of the experiment, all of the rabbits were euthanised to examine the histopathological changes and the cTnI immunoreactivity in cardiac muscle tissue. No changes in serum cTnI concentration were observed in the experimental group (EG) or control group (CG) at 0 and 4 h. In EG, the mean serum cTnI concentrations were 0.230 ± 0.209 and 1.177 ± 0.971 ng/ml at 8 and 12 h, respectively. In CG, the mean serum cTnI concentrations were 0.032 ± 0.014 and 0.031 ± 0.021 ng/ml at 8 and 12 h, respectively. Moreover, cytoplasmic cTnI immunoreactivity decreased in EG compared with that in CG (P<0.01). The results demonstrated that CLP induced a systemic inflammatory response and caused myocardial damage in rabbits.

REFERENCE INTERVALS FOR ERYTHROCYTE SEDIMENTATION RATE, LACTATE, FIBRINOGEN, HEMATOLOGY, AND PLASMA PROTEIN ELECTROPHORESIS IN CLINICALLY HEALTHY CAPTIVE GOPHER TORTOISES ( GOPHERUS POLYPHEMUS)

Currently available tests for the diagnosis of inflammatory disease in reptiles are limited and poorly sensitive. However, a number of hematological and plasma biochemical analytes are validated in the diagnosis of inflammation in mammals. The objective of this study was to establish reference intervals for erythrocyte sedimentation rate, lactate, heat-precipitated fibrinogen, hematology, and plasma protein electrophoresis based on total protein by biuret method in 23 clinically healthy, captive gopher tortoises ( Gopherus polyphemus) after successful rehabilitation and to determine differences by age, sex, and season. In order to investigate biological differences, samples were collected in April, July, and November. There were no sex differences in any measured analyte; however, there were significant differences by age and season. Immature animals (<2 kg) had significantly higher total protein, albumin : globulin ratio, pre-albumin, albumin, and α-1 globulin than adults. Tortoises sampled in the spring season had significantly higher total solids (refractometer) and lower eosinophils compared with animals sampled in the summer. Further investigation is required to determine the clinical utility of these analytes in the diagnosis of inflammation in this species.

Serum amyloid A and plasma protein electrophoresis fractions in farmed white-tailed deer

Tools to measure the acute-phase response have been utilized widely in veterinary medicine. Evaluation by plasma protein electrophoresis (PPEP) has become an increasingly common assay in veterinary clinical pathology. Commercial reagents for serum amyloid A (SAA) have been validated for use in a variety of wildlife species. We analyzed samples from 29 healthy fawns and 60 healthy adult farmed white-tailed deer (WTD; Odocoileus virginianus) using an automated assay for SAA and a semi-automated method for PPEP. The robust statistical method for reference interval generation was used. SAA levels in fawns (0.1-26 mg/L) were found to be significantly higher than those in adults (0.1-5 mg/L, p < 0.01). The mean total protein was significantly lower in fawns (48 ± 10 g/L, p < 0.01) than in adults (73 ±5 g/L). The albumin-to-globulin ratio was also lower in fawns (0.56 ± 0.14) than in adults (1.25 ± 0.19, p < 0.01). Changes in SAA levels were observed in a variety of clinically abnormal animals. The combined use of the automated and semi-automated assays in our study may provide an additional valuable assessment tool in the care of captive WTD populations, for research studies, and for monitoring free-ranging animals.

Hypercholesterolemia and hypertriglyceridemia as biochemical markers of disease in companion rabbits

BACKGROUND

Inflammation has important effects on lipid metabolism, but the relationship between hyperlipidemia, inflammation, and disease remains unknown in rabbits. While rabbits are sensitive to dietary hypercholesterolemia, the etiology of hyperlipidemia when fed non-atherogenic diets is uncertain.

OBJECTIVES

This study aimed to determine the association between hypercholesterolemia and patient characteristics, diseases, and select CBC and biochemistry analytes in rabbits, and to measure plasma lipoprotein lipid fractions in rabbits with inflammatory and other diseases.

METHODS

Complete blood count and plasma biochemistry data, including total cholesterol concentrations, were evaluated in 531 companion rabbits. Lipoprotein cholesterol fractions (non-high-density lipoprotein cholesterol [non-HDLc] and high-density lipoprotein [HDLc]) and triglycerides were measured using a colorimetric enzymatic assay in archived plasma from a subset of 267 rabbits. Rabbits were categorized by age, sex, spay/neuter status, breed, diet status (fed atherogenic dietary components or not), the organ system affected by disease, and the pathologic process.

RESULTS

Cholesterol was associated with fibrinogen (P = 0.01), globulins (P < 0.01), and heterophil (P < 0.01) concentrations. Adjusting for diet, rabbits with severe infection or sepsis (odds ratio [OR] = 13.25, 95% CI = 5.83-30.12), renal failure (OR = 14.42, 95% CI = 5.69-36.54), and hepatopathy (OR = 8.55, 95% CI = 3.55-20.62) had increased risks of hypercholesterolemia. Increased non-HDLc and triglyceride concentrations were also associated with these three disease states (P < 0.05).

CONCLUSIONS

Hyperlipidemia is associated with biochemical and CBC markers of inflammation, and with severe infection or sepsis, renal failure, and hepatopathy. Independent of diet, increased cholesterol, non-HDLc, and triglycerides are indicators of disease in companion rabbits.