Untargeted metabolomics reveals the effects of pre-analytic storage on serum metabolite profiles from healthy cats.

Untargeted metabolomics investigations have characterized metabolic disturbances associated with various diseases in domestic cats. However, the pre-analytic stability of serum metabolites in the species is unknown. Our objective was to compare serum metabolomes from healthy cats stored at -20°C for up to 12 months to samples stored at -80°C. Serum samples from 8 adult, healthy cats were stored at -20°C for 6 months, -20°C for 12 months, or -80°C for 12 months. Untargeted liquid chromatography-mass spectrometry was used to generate serum metabolite profiles containing relative abundances of 733 serum metabolites that were compared among storage conditions. Unsupervised analysis with principal component analysis and hierarchical clustering of Euclidian distances revealed separation of samples from individual cats regardless of storage condition. Linear mixed-effects models identified 75 metabolites that differed significantly among storage conditions. Intraclass correlation analysis (ICC) classified most serum metabolites as having excellent (ICC ≥ 0.9; 33%) or moderate (ICC 0.75-0.89; 33%) stability, whereas 13% had poor stability (ICC < 0.5). Biochemicals that varied significantly among storage conditions and classified with poor stability included glutathione metabolites, amino acids, gamma-glutamyl amino acids, and polyunsaturated fatty acids. The benzoate; glycine, serine and threonine; tryptophan; chemical (xenobiotics); acetylated peptide, and primary bile acid sub pathways were enriched among highly stable metabolites, whereas the monohydroxy fatty acid, polyunsaturated fatty, and monoacylglycerol sub-pathways were enriched among unstable metabolites. Our findings suggest that serum metabolome profiles are representative of the cat of origin, regardless of storage condition. However, changes in specific serum metabolites, especially glutathione, gamma-glutamyl amino acid, and fatty acid metabolites were consistent with increased sample oxidation during storage at -20°C compared with -80°C. By investigating the pre-analytic stability of serum metabolites, this investigation provides valuable insights that could aid other investigators in planning and interpreting studies of serum metabolomes in cats.

A systematic review and meta-analyses of the association between 4 mycoplasma species and lower respiratory tract disease in dogs.

BACKGROUND: The pathogenic role of mycoplasmas in the lower respiratory tract (LRT) of dogs is debated, because mycoplasmas can be isolated from both healthy and sick dogs. OBJECTIVES: To critically assess available data from controlled observational studies on the role of 4 mycoplasma species in LRT disease of dogs. DESIGN: Systematic review and meta-analyses. METHODS: Seven electronic databases were searched for relevant publications. Risk of bias was assessed by the Newcastle-Ottawa Scale. Meta-analyses, stratified by mycoplasmal species, were performed using a random effects Bayesian model with noninformative priors to estimate pooled odds ratios (ORs) and 95% confidence intervals (CIs) for the association between Mycoplasma cynos, Mycoplasma canis, Mycoplasma spumans, and Mycoplasma edwardii and LRT disease in dogs. RESULTS: Five studies were included from 1201 references identified. All studies dealt with M. cynos, whereas 3 dealt with the other mycoplasma species. A significant association was found between M. cynos and LRT disease (Bayesian OR, 3.60; CI, 1.31-10.29). Conversely, M. canis, M. spumans, and M. edwardii were not significantly associated with LRT signs (Bayesian OR, 1.06; CI, 0.10-14.63; Bayesian OR, 3.40; CI, 0.16-54.27; and Bayesian OR, 1.04; CI, 0.05-23.54, respectively). CONCLUSIONS AND CLINICAL IMPORTANCE: Results support a pathogenic role of M. cynos and a commensal role of M. canis and M. edwardii in LRT in dogs. Although the association was not significant based on the CI, the point estimate of the Bayesian OR was relatively high for M. spumans, making its role less clear. Mycoplasma cynos-specific polymerase chain reaction should be considered on samples from dogs with LRT.

Gallbladder Sludge in Dogs: Ultrasonographic and Clinical Findings in 200 Patients.

Echogenic luminal contents are often noted during ultrasonographic examination of the gallbladder (GB) in canine patients, but the significance of biliary sludge is not well understood. GB contents were evaluated during 200 sequential ultrasonographic scans performed at a veterinary school, and sludge was quantified using a 1-5 scale. GB volume was retrospectively estimated from stored images. Medical records were used to determine patient demographics, clinicopathologic findings, and diagnoses/disorders. The majority of dogs (66.5%) had some hyperechoic material within the GB. Four dogs were diagnosed with a mucocele. For statistical purposes, dogs with uniformly nonechogenic bile or minimal sludge (80.5%) were compared to those with >25% sludge (17.5%). Dogs with >25% sludge were significantly older than those with minimal sludge (8 versus 11 yr). Serum cholesterol and bilirubin concentrations and activities of both alkaline phosphatase and gamma-glutamyl transferase were not correlated with the presence of GB sludge. Dogs with spontaneous hyperadrenocorticism or hypothyroidism were more likely to have >25% sludge (odds ratio: 5.04). In addition, >25% sludge was associated with increased GB volume, suggesting that changes in GB function or contractility may impact the formation of biliary sludge in dogs.