Selected serum oxidative stress biomarkers in dogs with non-food-induced and food-induced atopic dermatitis

Oxidative Stress in Canine Diseases: A Comprehensive Review

Oxidative stress (OS), defined as a disruption in redox balance favoring oxidants, has emerged as a major contributor to numerous diseases in human and veterinary medicine. While several reviews have explored the implication of OS in human pathology, an exhaustive review of the canine species is lacking. This comprehensive review aims to summarize the existing literature on the role of OS in canine diseases, highlighting its potentially detrimental effect on various organs and systems. Some inconsistencies among studies exist, likely due to varying biomarkers and sample types. However, there is substantial evidence supporting the involvement of OS in the development or progression of numerous canine disorders, such as cardiovascular, oncologic, endocrine, gastrointestinal, hematologic, renal, neurologic, infectious, and parasitic diseases, among others. Additionally, this review discusses the efficacy of antioxidant and pro-oxidant therapeutic agents for these conditions. Dietary interventions to counteract OS in dogs have gained significant attention in recent years, although further research on the topic is needed. This review aims to serve as a foundational resource for future investigations in this promising field.

Effect of the Probiotic Bacillus subtilis DE-CA9TM on Fecal Scores, Serum Oxidative Stress Markers and Fecal and Serum Metabolome in Healthy Dogs

BACKGROUND

There is increasing interest in the use of Bacillus species as probiotics since their spore-forming ability favors their survival in the acidic gastric environment over other probiotic species. The subsequent germination of B. subtilis to their vegetative form allows for their growth in the small intestine and may increase their beneficial effect on the host. B. subtilis strains have also previously been shown to have beneficial effects in humans and production animals, however, no reports are available so far on their use in companion animals.

STUDY DESIGN

The goal of this study was therefore to investigate the daily administration of 1 × 109 cfu DE-CA9TM orally per day versus placebo on health parameters, fecal scores, fecal microbiome, fecal metabolomics, as well as serum metabolomics and oxidative stress markers in ten healthy Beagle dogs in a parallel, randomized, prospective, placebo-controlled design over a period of 45 days.

RESULTS

DE-CA9TM decreased the oxidative status compared to controls for advanced oxidation protein products (AOPP), thiobarbituric acid reactive substances (TBARS) and reactive oxygen metabolites (d-ROMS), suggesting an antioxidant effect of the treatment. Fecal metabolomics revealed a significant reduction in metabolites associated with tryptophan metabolism in the DE-CA9TM-treated group. DE-CA9TM also significantly decreased phenylalanine and homocysteine and increased homoserine and threonine levels. Amino acid metabolism was also affected in the serum metabolome, with increased levels of urea and cadaverine, and reductions in N-acetylornithine in DE-CA9TM compared to controls. Similarly, changes in essential amino acids were observed, with a significant increase in tryptophan and lysine levels and a decrease in homocysteine. An increase in serum guanine and deoxyuridine was also detected, with a decrease in beta-alanine in the animals that ingested DE-CA9TM.

CONCLUSIONS

Data generated throughout this study suggest that the daily administration of 1 × 109 cfu of DE-CA9TM in healthy Beagle dogs is safe and does not affect markers of general health and fecal scores. Furthermore, DE-CA9TM administration had a potential positive effect on some serum markers of oxidative stress, and protein and lipid metabolism in serum and feces.

Selected biomarkers of oxidative stress in healthy Beagle dogs: A preliminary study

Introduction

While oxidative stress has been studied in pathologic conditions in dogs, data in presumably healthy dogs and standardized protocols are lacking. This work purposed to bridge the gap by presenting provisional physiological ranges for oxidative stress biomarkers in a group of Beagle dogs.

Methods

Based on our long-standing clinical expertise in the field of oxidative stress, nine plasma biomarkers of oxidative stress were evaluated for their concentrations (mean ± SD) in 14 healthy adult Beagle dogs.

Results

Selected biomarkers were: vitamins C (7.90 ± 1.36 μg/mL) and E (34.1 ± 6.63 μg/mL), zinc (0.80 ± 0.17 mg/L), copper (0.54 ± 0.048 mg/L), selenium (256 ± 25.7 μg/L), total and oxidized glutathione (822 ± 108 μM and 3.56 ± 1.76 μM), myeloperoxidase (67.4 ± 56.2 ng/mL), and isoprostanes (340 ± 95.3 ng/mL). Glutathione peroxidase activity and superoxide anion production in whole blood were also measured. Glutathione peroxidase activity was 473 ± 34.0 IU/g of hemoglobin and superoxide anion production in whole blood was 18,930 ± 12,742 counts per 30 min. Reduced glutathione/oxidized glutathione and copper/zinc ratios were, respectively, 280 ± 139 and 0.70 ± 0.15. Sex-related differences were recorded for zinc (p = 0.0081), copper/zinc ratio (p = 0.0036) and plasma isoprostanes (p = 0.0045).

Conclusion

Provisional physiological norms covering 95% of our group were proposed for each biomarker and should be of interest for future studies of canine oxidative stress.

Oxidative Stress and Phototherapy in Atopic Dermatitis: Mechanisms, Role, and Future Perspectives

Atopic dermatitis is a chronic inflammatory skin disease in which the overproduction of reactive oxygen species plays a pivotal role in the pathogenesis and persistence of inflammatory lesions. Phototherapy represents one of the most used therapeutic options, with benefits in the clinical picture. Studies have demonstrated the immunomodulatory effect of phototherapy and its role in reducing molecule hallmarks of oxidative stress. In this review, we report the data present in literature dealing with the main signaling molecular pathways involved in oxidative stress after phototherapy to target atopic dermatitis-affected cells. Since oxidative stress plays a pivotal role in the pathogenesis of atopic dermatitis and its flare-up, new research lines could be opened to study new drugs that act on this mechanism, perhaps in concert with phototherapy.

Spectrophotometric assays for evaluation of Reactive Oxygen Species (ROS) in serum: general concepts and applications in dogs and humans

Reactive oxygen species (ROS) are reactive compounds derived from oxygen. In biological systems, an excessive amount of ROS can cause oxidative damage to biological macromolecules being involved in different diseases. Several assays have been developed in the last 30 years for ROS evaluation. The objective of this article will be to provide an update about the spectrophotometric methods currently used in the assessment of ROS in serum. The chemical basis of four different techniques will be reviewed, and examples of their possible applications will be provided. A particular emphasis about the practical applications of these assays in the dog will be made, but selected information about their use in humans will also be presented for comparative purposes, following a One-Health approach. The information about the spectrophotometric assays presented in this paper should be interpreted with caution once limited information about them is available yet, and further studies should be performed to clarify what they measure and their clinical application. Ideally, when applied to evaluate a sample's oxidative status, they should be incorporated in a panel of analytes where other oxidants, antioxidants, and biomarkers of inflammation were also included.

Targeted Metabolomics With Ultraperformance Liquid Chromatography-Mass Spectrometry (UPLC-MS) Highlights Metabolic Differences in Healthy and Atopic Staffordshire Bull Terriers Fed Two Different Diets, A Pilot Study

Background: While anecdotal evidence has long claimed that a raw meat-based diet (RMBD) improves the metabolic health of canines, no rigorous scientific study has clarified this issue. Canine atopic dermatitis (CAD) has also been linked to metabolic health, but its relation to diet remains poorly understood. This study investigates whether dietary choice is linked to metabolic health in healthy and CAD-diagnosed canines via targeted serum and urine metabolomic analysis of polar, non-ionic metabolites, as well as whether the underlying CAD condition modulates the response to nutritional intake. Materials and Methods: Serum metabolites of client-owned Staffordshire bull terriers, divided into CAD-diagnosed (n = 14) and healthy (n = 6) cohorts, were studied. Urine metabolites of a subset of the CAD-diagnosed canines (n = 8) were also studied. The canines were split into two cohorts based on diet. The first cohort were fed a commercially available high-fat, moderate-protein, low-carbohydrate RMBD (n = 11, CAD diagnosed n = 8, healthy n = 3). Those in the second cohort were fed a commercially available moderate-fat, moderate-protein, high-carbohydrate kibble diet (KD) (n = 9: CAD diagnosed n = 6, healthy n = 3). The diet intervention period lasted approximately 4.5 months (median 135 days). Statistical analyses of the serum profiles across all dogs (n = 20) and the urine profiles of the CAD-diagnosed subset (n = 8) were performed. Results and Discussion: The KD cohort was found to have higher concentrations of methionine than the RMBD cohort, both in serum (all dogs, p < 0.0001) and in urine (CAD-only cohort, p < 0.0002), as well as cystathionine and 4-pyridoxic acid. Methionine plays important roles in homocysteine metabolism, and elevated levels have been implicated in various pathologies. The CAD (n = 14) cohort dogs showed starker metabolic changes in response to diet regarding these pathways compared to the healthy (n = 6) cohort. However, there was no significant change in CAD severity as a result of either diet. Likely due to the higher meat content of the RMBD, higher concentrations of several carnitines and creatine were found in the RMBD cohort. Citrulline was found in higher concentrations in the KD cohort. Our findings provide insight into the relationship between diet and the serum and urine metabolite profiles of canines. They also suggest that neither diet significantly affected CAD severity.

The diagnostic and prognostic value of paraoxonase-1 and butyrylcholinesterase activities compared with acute-phase proteins in septic dogs and stratified by the acute patient physiologic and laboratory evaluation score

BACKGROUND

Sepsis is a complex syndrome that involves an increased oxidative stress status and dysregulation of cholinergic neurotransmission. Paraoxonase-1 (PON-1) and butyrylcholinesterase (BChE) activities have been identified as significant biomarkers to monitor such disorders in human septic patients.

OBJECTIVE

We aimed to determine the diagnostic and prognostic value of PON-1 and BChE vs other traditional acute-phase proteins such as albumin (ALB) and C-reactive protein (CRP) in septic dogs.

METHODS

This prospective observational study included 20 dogs with a diagnosis of sepsis, 27 with low-grade systemic inflammation (LGSI), and 10 healthy dogs that served as controls. Plasma samples were obtained from all dogs for analysis on admission, and then every 24-48 hours until discharge or death in the septic group.

RESULTS

Dogs with sepsis had lower PON-1 activity compared with dogs in the LGSI group (1.1 ± 0.10 vs 1.6 ± 0.08 U/mL, P = .002), but no differences in BChE activity were detected between the groups. PON-1, ALB, and CRP could successfully discriminate healthy animals from those with sepsis looking at the area under the curve (AUC) of the receiver operator characteristics curves (ROCs), which were 0.828, 0.903 and 1.000, respectively. Finally, although no differences were found among the groups for PON-1 or BChE activity, the nonsurvivor septic dogs had higher CRP (P = .002), lower ALB (P = .025) levels, and tended to have lower PON-1 (P = .082) activities than the survivors at patient death or discharge.

CONCLUSION

Septic dogs showed lower plasma PON-1 and higher BChE activities, but only PON-1 activity correlated with disease severity. Further studies are warranted to describe the usefulness of these new biomarkers of sepsis progression and recovery in dogs.

Reliability of different sets of criteria in diagnosing canine atopic dermatitis applied to a population of 250 dogs seen in a veterinary teaching hospital

BACKGROUND

Different sets of criteria are available in veterinary dermatology for the diagnosis of canine atopic dermatitis (cAD); there are limited data to assess their reliability.

HYPOTHESIS/OBJECTIVES

The aim of this study was to assess the discriminative and predictive ability of four sets in diagnosing cAD in a population of dogs with different skin diseases.

ANIMALS

Two hundred and fifty dogs examined in the dermatology unit of a veterinary teaching hospital.

METHODS AND MATERIALS

Dogs were diagnosed with cAD, flea infestation (FI), flea bite hypersensitivity (FBH), sarcoptic mange (SM) and other skin diseases (OD). FI, FBH and SM were pooled in one group of dermatoses mimicking cAD (MD). All nonatopic dogs were grouped as a "global population" (GP). Four criteria sets were applied to all dogs. For each set of criteria, sensitivity, specificity, positive and negative predictive values (PPV, NPV), likelihood ratios (LR) and diagnostic odds ratio (DOR) were calculated.

RESULTS

When applied to the GP, sensitivities ranged from 54 to 83%, specificities from 68 to 75% and PPVs from 35 to 43%. NPVs ranged from 87 to 94%. LRs and DORs were poor. When applied to MD, sensitivities remained unchanged, specificities and PPV were mildly higher, whereas NPVs were mildly lower and LRs and DORs were comparable.

CONCLUSIONS AND CLINICAL IMPORTANCE

This study showed that each set of criteria had a low diagnostic reliability when used alone. The use of more discriminant criteria integrated into a thorough clinical approach excluding MDs should be considered.