Validation of a Polar® human heart rate monitor for measuring heart rate and heart rate variability in adult dogs under stationary conditions

Heart rate variability (HRV) is considered to be a measure of autonomic regulation of cardiac activity for assessing stress and welfare in animals. Polar^® human heart rate monitors are frequently used in animal studies to measure HRV and have been validated for this use in cows, pigs, and horses. Although Polar^® monitors have been used in canine research to measure cardiac activity, we know of no studies that have tested its validity in dogs. Our objectives were as follows: (1) to collect interbeat interval (IBI) data while simultaneously using a Polar^® heart rate monitor and an electrocardiogram (ECG) monitor in awake healthy dogs under stationary conditions; (2) to compare Polar^® data with ECG data and examine whether any errors occurred in the Polar^® data; and (3) to assess the validity of these Polar^® data for recording time- and frequency-domain HRV data in dogs. IBI data from the Polar^® RS800CX monitor and a telemetric ECG monitor, the Televet 100, were recorded simultaneously for 5 continuous minutes in 10 adult beagles. The Polar^® data were compared with the ECG data to identify possible interbeat anomalies, such as those previously identified in pigs and horses. Statistical comparisons for a variety of time and frequency domain parameters (i.e., mean heart rate [ms], mean IBI [ms], R-R max [ms], R-R min [ms], standard deviation, total variance [ms²], and root mean square of successive differences) were performed. Time and frequency domain parameters from the Polar^® data were not significantly different from ECG data. The mean heart rate from the Polar^® data was 123.98 bpm (range: 101.57-138.35 bpm) and from ECG data was 123.33 bpm (range: 101.57-135.08 bpm). Bland–Altman analysis was used to measure the level of agreement between the 2 data sets. The mean difference between ECG and Polar^® data was 0.42 ms (limits of agreement: ?126.76 to 127.60 ms); more than 95% of the differences fell between these limits. We conclude that the Polar^® RS800CX digital R-R heart rate monitor is a promising instrument to reliably measure HRV in dogs under stationary conditions.     

Analytical validation of the Sysmex XT‐2000iV for cell counts in canine and feline effusions and concordance with cytologic diagnosis

Background: The Sysmex XT‐2000iV is a hematology analyzer that combines laser and impedance technology. Its usefulness for determining cell counts in canine and feline intracavitary effusions has not yet been studied. Objectives: The objectives of this study were to evaluate the analytical performance of the Sysmex XT‐2000iV for cell counts in effusions from dogs and cats, and to assess correlation with an impedance counter and concordance with diagnoses based on cytologic findings. Methods: Effusions (43 pleural, 23 peritoneal, 6 pericardial) were analyzed from 32 dogs and 34 cats. Total nucleated cell count (TNCC), HCT, and RBC count were determined on the Sysmex and compared with those obtained on an impedance counter (Hemat 8, SEAC). Imprecision, linearity, and limit of detection were determined for the Sysmex. An algorithm was designed using quantitative and qualitative data from the Sysmex to classify the effusions and the results were compared with diagnoses based on cytologic findings. Results: Intra‐assay and interassay coefficients of variation on the Sysmex were variable. Linearity of TNCC was ≥0.993 for dogs and cats, with the exception of effusions from cats with feline infectious peritonitis, which had delta (Δ) TNC values >3.0. In comparison with the Hemat 8, a proportional error was found for TNCC on the Sysmex. Effusion classification based on the algorithm was concordant with that obtained by cytologic examination in 43/72 (60%) samples. Discordant results usually were due to the misclassification of cells with similar morphology (such as mesothelial and carcinoma cells) in Sysmex scattergrams. Conclusion: The Sysmex XT‐2000iV provides a precise and accurate TNCC and has moderate concordance with cytologic findings for classifying canine and feline effusions. Although microscopic examination of effusions is necessary to achieve an accurate diagnosis, the Sysmex can provide preliminary information that may be helpful to cytopathologists.     

Evaluation of serum enzyme activities as predictors of passive transfer status in lambs

OBJECTIVE: To determine the associations between serum IgG concentration and serum activities of gamma-glutamyltransferase (GGT), alkaline phosphatase, aspartate aminotransferase, alanine aminotransferase, lactate dehydrogenase, and pseudocholinesterase for the potential use of these serum enzymes as predictors of passive transfer status in neonatal lambs. DESIGN: Prospective observational study. ANIMALS: 47 Sardinian lambs from birth to 2 days old. PROCEDURE: Serum enzyme activities were measured by use of commercially available kits and a clinical biochemical analyzer. Serum IgG concentration was determined by single radial immunodiffusion. Associations between serum IgG concentration and the activity of each serum enzyme were established by use of regression analysis. RESULTS: A significant correlation was detected between serum IgG concentration and serum GGT activity in 1- and 2-day-old lambs. Minimal correlations were detected between serum IgG concentration and serum alkaline phosphatase activity in 1-day-old lambs and serum pseudocholinesterase activity in 1- and 2-day-old lambs. No significant associations were detected between serum IgG concentration and serum activities of aspartate aminotransferase, alanine aminotransferase, and lactate dehydrogenase. A multiple linear regression model was accurate for the estimation of the natural logarithm of serum IgG concentration as a function of the natural logarithm of serum GGT activity and of the age of lambs at the time of sampling (adjusted R2 = 0.89). This model was then used to calculate the serum GGT activity equivalent to various serum IgG concentrations for 1- and 2-day-old lambs. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggested that passive transfer status in neonatal lambs can be successfully predicted by measurement of serum GGT activity but not by measurement of the other enzymes tested.     

Shifts in circulating lymphocyte subsets in cats with feline infectious peritonitis (FIP): pathogenic role and diagnostic relevance

Cats with feline infectious peritonitis (FIP) are usually lymphopenic and have lymphoid depletion evident in spleen and lymph nodes. In particular, the number of CD4+ lymphocytes in tissues decreases during the evolution of FIP lesions. This decrease is most likely due to increased lymphocyte apoptotic rate. In contrast, cats infected with the Feline Coronavirus (FCoV) develop a follicular hyperplasia in the peripheral lymph nodes. The current study was devised to evaluate the possible pathogenic role of shifts in circulating lymphocyte subsets in FIP. Peripheral blood from cats with FIP was evaluated and compared with peripheral blood from clinically healthy cats living in both FCoV-free and FCoV-endemic catteries. Blood from cats with diseases other than FIP was also examined in order to define the diagnostic relevance of the changes. Lymphocyte subsets were analysed by flow cytometry, using a whole blood indirect immunofluorescence technique and mAbs specific for feline CD5, CD4, CD8, CD21. The results of the current study suggest that cats recently infected with FCoV that do not develop the disease have a transient increase in T cells; cats from groups with high prevalence of FIP have a moderate but persistent decrease in T cell subsets; cats with FIP have a very severe decrease in all the subsets of lymphocytes. Moreover, during FIP many lymphocytes do not express any membrane antigen, most likely due to early apoptosis. Cats with diseases other than FIP also had decreased number of lymphocytes: as a consequence, the diagnostic relevance of these findings is very low. Nevertheless, the lack of flow cytometric changes had a high negative predictive value (NPV), thus allowing to exclude FIP from the list of possible diagnoses in cats with normal cytograms.     

Decreased sialylation of the acute phase protein alpha1-acid glycoprotein in feline infectious peritonitis (FIP)

Feline infectious peritonitis (FIP) is an immune-mediated disease of domestic and exotic felides infected with feline coronavirus. FIP is characterized by the overexpression of an acute phase protein, the alpha1-acid glycoprotein (AGP). In humans, AGP is a heavily glycosylated protein that undergoes several modifications of its glycan moiety during acute and chronic inflammatory pathologies. We studied the changes in AGP glycosylation in the course of FIP. Specifically, we focussed our attention on the degree of sialylation, fucosylation and branching. This study presents a purification method for feline AGP (fAGP) from serum, using an ion exchange chromatography strategy. The glycosylation pattern was analyzed in detail by means of interaction of purified fAGP with specific lectins. In particular, Sambucus nigra agglutinin I and Maackia amurensis agglutinin lectins were used to detect sialic acid residues, Aleuria aurantia lectin was used to detect L-fucose residues and Concanavalin A was used to evaluate the branching degree. By this method we showed that fAGP did not present any L-fucose residues on its surface, and that its branching degree was very low, both in normal and in pathological conditions. In contrast, during FIP disease, fAGP underwent several modifications in the sialic acid content, including decreased expression of both alpha(2-6)-linked and alpha(2-3)-linked sialic acid (76 and 44%, respectively when compared to non-pathological feline AGP).