Measurement of salivary adiponectin concentrations in dogs

Insulin, but not adiponectin, is detectable in equine saliva using an automated, commercial assay

BACKGROUND

The hormones insulin and adiponectin are commonly measured in equids because of their involvement in endocrinopathic laminitis. These are currently measured in serum/plasma, although jugular venipuncture can cause stress in some animals and may be impossible in needle-shy individuals. However, both hormones can be measured in saliva in other species.

OBJECTIVES

To determine whether [insulin] and [total adiponectin] are detectable in equine saliva using automated assays and whether saliva collection is associated with changes in stress indicators. Additionally, the correlation between serum and salivary [insulin] was investigated.

STUDY DESIGN

In vivo experiment.

METHODS

Paired blood and saliva samples were collected from eight adult ponies at multiple time-points (n = 45 paired samples). [Insulin] and [total adiponectin] were measured using automated assays validated for equine serum/plasma. Blink rates and heart rates were determined, using video recordings and a wearable heart rate monitor respectively, to assess the effects of sample collection on stress indicators compared with a control situation without a stressful stimulus.

RESULTS

[Total adiponectin] was undetectable in saliva. However, salivary [insulin] was measurable with acceptable inter-assay (1.3 ± 0.9%) and intra-assay (1.1 ± 0.6%) variability. Blink and heart rates during saliva collection did not differ significantly from those in the control setting. Serum and salivary [insulin] were not significantly correlated.

MAIN LIMITATIONS

Small sample size comprising native UK ponies; potential sampling bias as animals were recruited to the study partly based on their behaviour during blood sampling; saliva collected from unfasted animals.

CONCLUSIONS

Insulin is measurable in equine saliva using an automated assay currently available in the UK, but further validation and the determination of specific diagnostic thresholds are required. Saliva collection was not associated with changes in stress indicators. Further research is therefore needed to determine the potential of equine saliva as a non-invasive alternative to blood for insulin determination.

Changes in the salivary proteome of beagle dogs after weight loss

Being overweight or obese represents an important health issue in humans and pets. The aim of this study was to investigate changes in the salivary proteome of overweight beagles after induced weight loss to better understand the physiological changes involved in this process. Five overweight/obese neutered males of pure breed beagles were evaluated. During the 3-mo period of weight loss, each animal received a strictly controlled amount of a low fat commercial diet per day. Body condition scores (BCS), body weight (BW), and serum biochemical parameters (total cholesterol, triglycerides, and C-reactive protein) were assessed weekly. Quantitative proteomics analysis by SWATH was used to evaluate the salivary proteome changes induced by weight loss treatment. BCS, BW, serum total cholesterol concentration, and abundances of 23 salivary proteins differed significantly between before and after treatment. Some of the altered protein amounts, namely of peptidyl-prolyl cis-trans isomerase, fructose-bisphosphate aldolase C, and 78-kDa glucose-regulated protein, increased after weight loss. These proteins are related with the immune system, inflammatory status, oxidative stress, and glucose metabolism. The results obtained suggest a potential use of salivary proteins in monitoring physiological changes in dogs subjected to weight loss. Moreover, the type of changes identified reinforces the postulated physiological improvements, which weight loss induces. Further research is needed to determine whether the changes observed in this study are due to weight loss, dietary changes, or a combination of both.

Biomarkers of health and welfare: A One Health perspective from the laboratory side

A biomarker is any measurement reflecting an interaction between a biological system and a potential hazard, which may be chemical, physical, or biological. The One World, One Health concept established that human and animal health and the environmental state are highly interconnected, sharing common aspects that can be applied globally in these three components. In this paper, we review how the concept of One Health can be applied to biomarkers of health and welfare, with a special focus on five points that can be applied to any biomarker when it is expected to be used to evaluate the human, animal or environmental health. Three of these points are: (1) the different biomarkers that can be used, (2) the different sample types where the biomarkers can be analysed, and (3) the main methods that can be used for their measurement. In addition, we will evaluate two key points needed for adequate use of a biomarker in any situation: (4) a proper analytical validation in the sample that it is going to be used, and (5) a correct selection of the biomarker. It is expected that this knowledge will help to have a broader idea about the use of biomarkers of health and welfare and also will contribute to a better and more accurate use of these biomarkers having in mind their One Health perspective.

Serum and salivary adiponectin dynamics in septic and non-septic systemic inflammation in a canine model

Adiponectin is a 30 kDa protein hormone that has anti-atherogenic properties, being an insulin-sensitizing and anti-inflammatory molecule. Salivary adiponectin concentrations correlate positively with serum, thus, saliva was indicated as appropriate biofluid for its measurement in different clinical situations. However, inflammation was indicated as main confounding factor when evaluating the usefulness and the reliability of determination of salivary adiponectin. The aim of the present report was to evaluate the dynamics of salivary and serum adiponectin in systemic non-septic and septic inflammation using a dogs as a model. Forty bitches were enrolled. Seventeen dogs were healthy (group I, non-septic) and 23 bitches were diagnosed with pyometra (group II, septic). Ovariohysterectomy was performed for all animals. Saliva and blood samples were collected before (D0) and 3 (D3) and 10 (D10) days after ovariohysterectomy. At D0, Group I showed higher serum and salivary adiponectin than group II, although statistical significance was only detected in salivary adiponectin between the two groups at D0 (P = 0.001). In serum, adiponectin was higher on D0 than on D3 and tended to reach pre-surgery values on D10 in both groups. Salivary adiponectin showed similar behaviour to serum in Group I, while in group II salivary adiponectin concentrations were lowest on D0 and tended to increase on D3 and D10. The data obtained in present study describe for the first time the comparative behavior of salivary adiponectin in non-septic and septic inflammation. Salivary, and not serum, adiponectin seemed to mimic better the inflammatory and general health status.

A new highly sensitive immunoassay for the detection of adiponectin in serum and saliva of dogs and its application in obesity and canine leishmaniosis

Adiponectin is an adipokine that exerts insulin-sensitizing and antiinflammatory properties. The aim of this study was to develop and validate a new heterologous ultrasensitive assay based on amplified luminescent technology for adiponectin determination in serum and saliva of dogs. A complete analytical validation of the assay was made in these fluids, and also this assay was applied to quantify adiponectin in serum and saliva of obese and lean dogs and dogs with leishmaniosis. These conditions were selected because in obesity there is a controversy about how adiponectin concentrations change in dogs, and in case of canine leishmaniosis, although it is described a decrease in serum adiponectin, there are not studies about how adiponectin changes after treatment. A total of 11 dogs were used in the validation and 26 dogs with different body condition and 8 with canine leishmaniosis were used for the clinical evaluation of the new assay for adiponectin quantification in serum and saliva of dogs. The analytical evaluation showed that the developed method could measure adiponectin in serum and saliva of dogs with high repeatability and sensitivity, adding a limit of quantification lower than commercially available ELISAs. In addition, significantly higher adiponectin concentrations were found in lean dogs and a correlation between serum and saliva was observed (P < .01). Moreover, dogs with leishmania presented reduced levels of adiponectin in serum. In conclusion, a new assay has been developed for adiponectin measurements which is more sensitive and faster than the traditional ELISA assays requiring less sample volume.

Comparative proteomic analysis of saliva from dogs with and without obesity-related metabolic dysfuntion

Dogs develop only some of the components of the human metabolic syndrome (MetS). Thus, in order to study possible MetS-related alterations in dogs, human MetS criteria were adapted to define canine MetS or so-called obesity-related metabolic dysfunction (ORMD). The main objective of this study was to identify changes in the salivary proteome of obese dogs with ORMD in comparison with obese dogs without ORMD which may constitute potential salivary biomarkers for assessing ORMD. In a first phase, 12 adult obese dogs with ORMD (N = 6) and without ORMD (N = 6) were included in the study. Subsequently, and with the aim of validating and strengthening the results, additional 12 obese dogs (6 with and 6 without ORMD) were tested in an independent experiment following the same protocol. Saliva samples were subjected to a quantitative proteomics analysis and the levels of nine salivary proteins were found to be significantly different between groups, among them those which had greatest fold-change were proteins involved in glycolysis and oxidative stress. In conclusion, despite metabolic syndrome to include different combinations of diseases, the observation of differences in salivary proteome suggests a potential of this fluid to understand the pathophysiology of the disease. SIGNIFICANCE: This is the first study evaluating proteomes of saliva in dogs, as a non invasive sample, in order to increase knowledge about the metabolic/physiopathological changes related to obesity-related metabolic dysfunction (ORMD) together with the identification of potential biomarkers for its diagnosis. As approximately 20% of dogs with naturally occurring obesity were described to suffer ORMD associated with insulin resistance and hypoadiponectinemia, the fact that indicate possible links between ORMD and associated diseases.

The Saliva Proteome of Dogs: Variations Within and Between Breeds and Between Species

Saliva is a complex multifunctional fluid that bathes the oral cavity to assist in soft and hard tissue maintenance, lubrication, buffering, defense against microbes, and initiating digestion of foods. It has been extensively characterized in humans but its protein composition in dogs remains poorly characterized, yet saliva composition could explain (patho) physiological differences between individuals, breeds and with humans. This pilot discovery study aimed to characterize canine saliva from two breeds, Labrador retrievers and Beagles, and to compare this with human saliva using quantitative mass spectrometry. The analysis demonstrated considerable inter-individual variation and difference between breeds; however these were small in comparison to the differences between species. Functional mapping suggested roles of detected proteins similar to those found in human saliva with the exception of the initiation of digestion as salivary amylase was lacking or at very low abundance in canine saliva samples. Many potential anti-microbial proteins were detected agreeing with the notion that the oral cavity is under continuous microbial challenge.

Salivary pH, calcium, phosphorus and selected enzymes in healthy dogs: a pilot study

BACKGROUND

Saliva in dogs, as in humans, is a complex fluid secreted by different salivary glands in the oral cavity to protect the oral mucosa and teeth. The use of saliva as a substitute for blood in diagnosing and prognosticating disease in humans is widely accepted. Salivary biochemistry has also been used as a marker for periodontal disease in humans. No studies have as yet investigated the relation between salivary biochemistry and periodontal disease in dogs, however; neither has the salivary composition of healthy dogs with no oral disease been assessed. The purpose of this study was to obtain an overview on pH distribution and a set of salivary biochemical analytes (calcium, phosphorus, lactate dehydrogenase, lysozyme and amylase) commonly related to oral health in humans in a subset population of healthy young dogs with no periodontal disease or previous oral disease. Data were analyzed to gather salivary reference ranges for pH and each parameter and to assess a possible correlation between salivary and serum analytes.

RESULTS

Twenty-nine adult client-owned dogs were recruited for the study. Lactate dehydrogenase and lysozyme showed higher concentrations in saliva than in serum, whereas amylase showed the contrary. Salivary biochemistry values did not differ between males and females or between non-neutered and neutered individuals. No significant correlations between salivary and serum calcium, phosphorus, lactate dehydrogenase, amylase and lysozyme were identified in this study. Data allowed intervals for the salivary pH and other analytes investigated to be obtained from healthy dogs with healthy oral conditions.

CONCLUSIONS

These preliminary data can contribute to enlarge our understanding of the functional role of saliva and its relation to oral health in dogs.

Myocardial Adiponectin Isoform Shift in Dogs with Congestive Heart Failure-A Comparison to Hibernating Brown Bears (Ursus arctos horribilis)

Adiponectin is the most abundant plasma adipokine, and is well known for its role in energy homeostasis and cardiac protection. In humans with dilated cardiomyopathy, myocardial adiponectin protein expression is reduced compared to normal hearts and has been implicated in the pathology of cardiomyopathy. Serum adiponectin levels are often conflicting, with higher levels associated with poor survival in humans with congestive heart failure (CHF). We evaluated adiponectin serum concentrations and myocardial protein expression in dogs with naturally occurring myxomatous mitral valve disease and CHF. We compared the findings to active and hibernating brown bears as bears are adapted to endure an extreme period of low cardiac output during their annual hibernation. Bears exhibited largely the active high-molecular weight (HMW) versus the low-molecular weight isoforms of myocardial adiponectin (HMW:LMW = 6.3) during both the active period and hibernation, while healthy dogs exhibited a more balanced mix of isoforms. Dogs with CHF expressed predominately HMW isoforms of adiponectin (HMW:LMW = 12.5), appearing more similar to bears. In contrast to humans, serum adiponectin was significantly lower in dogs with CHF and lowest levels in the severest CHF class. In both dogs and bears, myocardial adiponectin was expressed independent of circulating adiponectin concentrations, suggesting a local regulatory mechanism within the heart.

Cardiac and Metabolic Variables in Obese Dogs

Background

The etiology of obesity‐related cardiac dysfunction (ORCD) is linked to metabolic syndrome in people. Studies have indicated that obese dogs have components of metabolic syndrome, warranting evaluation for ORCD in obese dogs.

Objectives

To evaluate cardiac structure and function and metabolic variables in obese dogs compared to ideal weight dogs.

Animals

Forty‐six healthy, small‐breed (<25 pounds), obese dogs (n = 29) compared to ideal weight dogs (n = 17).

Methods

A cross‐sectional study of cardiac structure and function by standard and strain echocardiographic measurements and quantification of serum metabolic variables (insulin:glucose ratios, lipid analysis, adiponectin, inflammatory markers).

Results

Compared to the ideal weight controls, obese dogs had cardiac changes characterized by an increased interventricular septal width in diastole to left ventricular internal dimension in diastole ratio, decreased ratios of peak early to peak late left ventricular inflow velocities, and ratios of peak early to peak late mitral annular tissue velocities, and increased fractional shortening and ejection fraction percentages. The left ventricular posterior wall width in diastole to left ventricular internal dimension in diastole ratios were not significantly different between groups. Systolic blood pressure was not significantly different between groups. Obese dogs had metabolic derangements characterized by increased insulin:glucose ratios, dyslipidemias with increased cholesterol, triglyceride, and high‐density lipoprotein concentrations, decreased adiponectin concentrations, and increased concentrations of interleukin 8 and keratinocyte‐derived chemokine‐like inflammatory cytokines.

Conclusions and Clinical Importance

Compared to ideal weight controls, obese dogs have alterations in cardiac structure and function as well as insulin resistance, dyslipidemia, hypoadiponectinemia, and increased concentrations of inflammatory markers. These findings warrant additional studies to investigate inflammation, dyslipidemia, and possibly systemic hypertension as potential contributing factors for altered cardiac function.

Measurement of Creatine kinase and Aspartate aminotransferase in saliva of dogs: a pilot study

Background

Muscle enzymes in saliva have been reported to be possible markers of heart and muscle damage in humans. The aim of this study was to assess if Creatine kinase (CK) and Aspartate aminotransferase (AST) activities could be measured in canine saliva, and to evaluate their possible changes in situations of muscle damage.

Results

The spectrophotometric assays for CK and AST measurement in saliva of dogs showed intra- and inter-assay imprecision lower than 1 and 16% and coefficients of correlation close to 1 in linearity under dilution tests. Healthy dogs showed activities in saliva of CK between 27 and 121 U/L and AST between 46 and 144 U/L, whereas in saliva of dogs with muscle damage CK ranged between 132 and 3862 U/L and AST between 154 and 4340 U/L. Positive moderate correlations were found between saliva and serum activities of the two enzymes (CK, r = 0.579; P = 0.001; AST, r = 0.674; P = 0.001).

Conclusions

CK and AST activities can be measured in canine saliva with commercially available spectrophotometric assays. In addition these enzymes show higher values in saliva of dogs with muscle damage and their values are moderately correlated with those of serum.