Validation of two ELISA assays for total ghrelin measurement in dogs

The aim of this study was to validate two commercially available ELISA assays for total ghrelin measurement in dogs: one canine-specific and one originally designed for measuring human ghrelin. The two assays showed intra-assay coefficient of variations (CVs) lower than 10%, while the inter-assay CVs exceeded the 15% limit. Sample dilutions resulted in linear regression equations with correlation coefficients close to 1. In order to compare methods and verify ability of the ghrelin assays to differentiate between low and high levels, ghrelin concentrations were measured in plasma samples obtained before and at different times after glucose administration in five Beagle dogs. A statistically significant changes in ghrelin after glucose administration was recorded only with assay B. In conclusion, the human ELISA validated in this study showed a good intra-assay precision, accuracy, and when applied to the glucose injection study, was better in distinguishing high and low canine ghrelin levels than the canine ELISA assay.     

Dominance in domestic dogs revisited: Useful habit and useful construct?

In the last decade, the validity and relevance of the dominance model was regularly put into question regarding relationships between canids like dogs and wolves, and consequently, human–dog relationships as well. The concept underlying this model, scientifically defined as an intervening variable reflecting status difference between individuals, is applicable when formal status signals symbolize the long-term relationship between individuals, resulting in a formalized dominance hierarchy. This article reviews the basics underlying the concept of dominance and reflects on the value and importance of some new quantitative studies on the applicability of the concept of dominance in domestic dogs. The conclusions are, first, that formal dominance is present in the domestic dog, expressed by context-independent unidirectional formal status signals. Consequently, formal dominance (e.g., submission) plays an important role in assessing status in dog–dog relationships. Second, that nonverbal status–related communication in humans resembles that in dogs to a considerable degree, and hence dogs may be well able to interpret this human status–related nonverbal communication from their perspective. Dominance is therefore also likely to play a role in human–dog relationships. Hence, the dominance concept might be useful to explain the development of certain problems in dog–dog and dog–human relationships. However, enforcing a dominant status by a human may entail considerable risks and should therefore be avoided.     

Behavioral and cardiac responses by dogs to physical human–dog contact

Measures of behavioral responses and cardiovascular parameters to evaluate and assess animal well-being are well established. A major aspect of companion animal well-being seems to originate from direct human–animal interaction. For pet dogs, the manner in which they obtain and respond to petting and hugs could interfere with the development of a pleasant human–dog companionship. Therefore, the purpose of this study was to evaluate cardiovascular responses by dogs to physical human–dog contact and to assess these physiological responses in relation to the dogs' behavioral responses. Noninvasive measurements of privately owned dogs' (N = 28) cardiovascular parameters and behavioral responses were carried out during 9 physical human–dog interactions (e.g., petting the dog on its back, holding a forepaw of the dog). The behavioral responses were grouped in categories, for example, redirected behavior, displacement activity, and appeasement gesture. The mean heart rate (HR) and 2 cardiac activity parameters, standard deviation of normal-to-normal R–R intervals (SDNN) and root mean square of successive heartbeat interval differences/SDNN (RMSSD/SDNN) ratio, differed significantly among the human–dog interactions. Petting and holding the dog around the head was associated with an increased SDNN. An increased vagal tone was the dogs' responses to being petted at the chest. Displacement activities correlated negatively with all cardiovascular parameters (HR, SDNN, RMSSD, and RMSSD/SDNN ratio). Appeasement gestures were positively correlated with HR and occurred less under an increased vagal tone. The behavioral strategies, that is, freezing (standing motionless with all legs on the floor) and withdrawal (moving backward without any agonistic display) were negatively associated with the cardiac activity parameters, RMSSD and RMSSD/SDNN ratio. The dogs' behavioral and physiological responses suggest that some common physical human–dog interactions perceived as unpleasant by dogs. Emphasis on human signaling in human–dog interactions encourages development of recommendations for pleasant and safe human–dog contact to enhance dogs' well-being and the human–dog relationship.     

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.     

Concentrations of haptoglobin in bovine plasma determined by ELISA or a colorimetric method based on peroxidase activity

The objective was to compare different procedures for determination of haptoglobin in bovine plasma. Nine Angus steers were vaccinated against Mannheimia haemolytica to stimulate an acute‐phase response. Blood samples were collected immediately prior to vaccination (day 0), and on days 1, 3, 5, 7 and 10. Plasma samples were frozen in duplicates at ?80 °C. One set of the duplicates was analysed for haptoglobin concentrations using a commercial ELISA kit. A day effect was detected (p < 0.01) because haptoglobin peaked on day 3 and returned to baseline on day 7 relative to vaccination. The second duplicate was analysed using a procedure that measures haptoglobin–haemoglobin complexing by estimating differences in peroxidase activity (CPPA) with results expressed as optical density. Further, based on the ELISA results, the plasma sample with the greatest haptoglobin concentration was also serially diluted into a plasma sample with negligible haptoglobin concentration from the same steer (1:1 through 1:1024 dilution). These dilutions were used within the CPPA method to generate a standard curve and estimate plasma haptoglobin concentrations (CPPA + STD). A linear standard curve was generated (r² = 0.99). A day effect similar to the ELISA method was detected for the CPPA and CPPA + STD methods (p < 0.01). Results obtained from CPPA and ELISA methods were positively correlated (r = 0.97; p < 0.01). The values generated by the CPPA + STD procedure were similar (p = 0.38) compared to the values generated by the ELISA method. In conclusion, assessing concentrations of haptoglobin in bovine plasma using the CPPA and CPPA + STD methods generate highly correlated or similar results, respectively, compared to ELISA. Therefore, the CPPA + STD and CPPA methods can be used as a less expensive alternative to ELISA to determine concentrations or monitor changes in plasma haptoglobin in bovine samples.     

Campylobacter species in cats and dogs in South Australia

BACKGROUND: Campylobacter enteritis was the most frequently notified infectious disease in Australia in 1996 and Campylobacter species have been associated with extra-intestinal infections such as purulent arthritis and Guillian-Barré syndrome. Dogs and cats are known to carry campylobacteria and contact with household pets have been implicated as possible sources of human infection. OBJECTIVE: To provide information on the species of campylobacter carried by cats and dogs in South Australia. METHODS: Faecal samples were collected from stray and owned cats and dogs and feral cats. Campylobacter-like organisms were isolated using selective media and filtration methods. They were then characterised by biochemical tests, antibiotic resistance and growth patterns under various conditions. Husbandry factors that could have influenced the carriage rates were examined both as single variables and in a multivariate logistic regression. RESULTS: Campylobacter upsaliensis and C jejuni were found in 11% and 4% of cats, respectively, whereas 34% dogs carried C upsaliensis, 7% C jejuni and 2% C coli. Intensive housing and open drains were found to be significant risk factors and increased the carriage rate by 2 and 2.6 times, respectively. CONCLUSION: Dogs and cats are a potential reservoir for human enteric infections with campylobacters.     

Semiautomatic and robotic methods for determining serum haptoglobin levels

The assay of Makimura and Suzuki for serum haptoglobin has been adapted to use one tube with both semiautomated and robotic methods. The adaptation permits the determination of haptoglobin in several hundred serum samples per day. Both methods were strongly correlated with the original two-tube method and had within-assay variability of 4.4% for the semiautomated and 4.8% for the robotic method. Day-to-day variability averaged 6.0% for the semiautomated and 5.5% for the robotic method. The y-intercepts for both assays were higher than that of the original two-tube method, and thus, reference values are higher than those reported previously.