The preanalytic phase in veterinary clinical pathology.

This article presents the general causes of preanalytic variability with a few examples showing specialists and practitioners that special and improved care should be given to this too often neglected phase. The preanalytic phase of clinical pathology includes all the steps from specimen collection to analysis. It is the phase where most laboratory errors occur in human, and probably also in veterinary clinical pathology. Numerous causes may affect the validity of the results, including technical factors, such as the choice of anticoagulant, the blood vessel sampled, and the duration and conditions of specimen handling. While the latter factors can be defined, influence of biologic and physiologic factors such as feeding and fasting, stress, and biologic and endocrine rhythms can often not be controlled. Nevertheless, as many factors as possible should at least be documented. The importance of the preanalytic phase is often not given the necessary attention, although the validity of the results and consequent clinical decision making and medical management of animal patients would likely be improved if the quality of specimens submitted to the laboratory was optimized.

Functional investigation of a QTL affecting resistance to Haemonchus contortus in sheep.

This study reports a functional characterization of a limited segment (QTL) of sheep chromosome 12 associated with resistance to the abomasal nematode Haemonchus contortus. The first objective was to validate the identified QTL through the comparison of genetically susceptible (N) and resistant (R) sheep produced from Martinik × Romane back-cross sheep. The R and N genotype groups were then experimentally infected with 10 000 H. contortus larvae and measured for FEC (every three days from 18 to 30 days post-challenge), haematocrit, worm burden and fertility. Significant differences in FEC and haematocrit drop were found between R and N sheep. In addition, the female worms recovered from R sheep were less fecund. The second step of the characterization was to investigate functional mechanisms associated with the QTL, thanks to a gene expression analysis performed on the abomasal mucosa and the abomasal lymph node. The gene expression level of a candidate gene lying within the QTL region (PAPP-A2) was measured. In addition, putative interactions between the chromosome segment under study and the top ten differentially expressed genes between resistant MBB and susceptible RMN sheep highlighted in a previous microarray experiment were investigated. We found an induction of Th-2 related cytokine genes expression in the abomasal mucosa of R sheep. Down-regulation of the PAPP-A2 gene expression was observed between naïve and challenged sheep although no differential expression was recorded between challenged R and N sheep. The genotyping of this limited region should contribute to the ability to predict the intrinsic resistance level of sheep.

Plasma N-terminal pro-B-type natriuretic peptide concentration helps to predict survival in dogs with symptomatic degenerative mitral valve disease regardless of and in combination with the initial clinical status at admission.

OBJECTIVES: Although mitral valve disease (MVD) is the most common canine heart disease, readily available prognostic markers of the disease are still lacking. The aim of this study was to evaluate the comparative ability of N-terminal pro-B-type natriuretic peptide plasma concentration (NT-proBNP) and various echocardiographic variables to predict outcome in dogs with MVD. ANIMALS, MATERIALS AND METHODS: Seventy-four dogs with ISACHC classes 2 and 3 MVD (Groups A and B, respectively) were prospectively recruited. NT-proBNP and several echo-Doppler variables at inclusion were compared as predictors of outcome at 6 months in 54/74 dogs. RESULTS: NT-proBNP was significantly higher in Group B than in Group A (P<0.0001), and was the only tested variable significantly different between survivor and non-survivor dogs in both groups (P<0.05). In the whole canine population, a threshold of 1500 pmol/L could discriminate survivor from non-survivor dogs with a sensitivity and specificity of 80% and 73%, respectively. When combining ISACHC class with NT-proBNP levels, a cut-off of 1265 pmol/L was predictive of survival in Group A, whereas the cut-off was 2700 pmol/L for Group B. CONCLUSIONS: NT-proBNP is correlated with MVD severity and could be used in combination with clinical status to predict cardiac outcome.

Effect of repeated freeze-thaw cycles on routine plasma biochemical constituents in canine plasma.

BACKGROUND: The effect of repeated freeze-thaw cycles on plasma constituents has not been assessed in dogs, although such a procedure is not uncommon to use in routine laboratory practice. OBJECTIVE: To assess the effect of freeze-thaw cycles on routine plasma constituents in healthy dogs. METHODS: Six healthy adult dogs were used. Blood was sampled and placed in heparinized tubes. After centrifugation, plasma was separated into 5 aliquots. One aliquot was considered as the reference aliquot and used immediately for the assay of all of the biochemical constituents. All of the other aliquots were stored at 20 degrees C. Three aliquots underwent 1, 2, or 3 freeze-thaw cycles during a 1- to 3-day period. The last aliquot remained at 20 degrees C throughout the study and was thawed on the third day. The following biochemical constituents were assayed: glucose, urea, creatinine, total proteins, sodium, potassium, chloride, calcium, phosphates, aspartate aminotransferase (AST), alanine aminotransferase (ALT), creatine kinase (CK), and alkaline phosphatase (ALP). RESULTS: No clinically relevant change was observed between the different aliquots for all of the constituents. CONCLUSION: Repeated freeze-thaw cycles do not cause changes in the biochemical constituents studied in canine plasma.

High resolution protein electrophoresis of 100 paired canine cerebrospinal fluid and serum.

This study was performed to investigate the diagnostic relevance of cerebrospinal fluid (CSF) high resolution electrophoresis. The laboratory technique was applied to 100 paired samples of canine CSF and serum, with paired samples tested during the same analytical run, as recommended in human medicine. Ninety four of the dogs had a neurological disease and 6 healthy dogs served as a control group. A strong linear correlation between CSF total protein concentration and the albumin quota (AQ) was found in the control group and in the inflammatory (infectious or noninfectious), neoplastic, and miscellaneous groups: AQ = 0.015 CSF total protein--0.102, r = 0.990. This correlation suggests that an increased CSF total protein concentration can be an indicator of blood brain barrier dysfunction. The highest median AQ value was found in the aseptic suppurative meningitis group, but no statistical differences were found between this and the other groups. The AQ, calculated with this technique, did not provide any additional information. Moreover, although unexpected, the electrophoretic profiles were not characteristic of any particular disease. In conclusion, this study did not confirm high resolution electrophoresis of paired CSF and serum samples to be a valuable ancillary diagnostic tool for canine neurological diseases.