Advances in echocardiography.

Echocardiography is an exceptionally useful technique for diagnosing cardiovascular disease in small animals. It is noninvasive and provides a wealth of data concerning cardiac morphology and function. For many patients, echocardiography is the definitive diagnostic tool. A well-performed study coalesces the findings of the physical examination, electrocardiogram, and radiographs into a clearly defined diagnosis on which treatment decisions can be based. More so than other diagnostic techniques, echocardiography is highly operator dependent and relies on the proper acquisition and interpretation of results by an examiner who is familiar with the principles, capabilities, and limitations of ultrasound imaging.This article reviews the basics of echocardiography, measurement of cardiac dimensions, and assessment of cardiac function. Within these sections, emerging technologies that expand the capabilities of the echocardiographic examination are introduced.     

Molecular epidemiology of two fowl cholera outbreaks on a free-range chicken layer farm.

Two outbreaks of fowl cholera on a multiage free-range egg farm were investigated. The outbreaks occurred in 1994 and 2002. A total of 22 strains of Pasteurella multocida were available for study, 11 from the 1994 outbreak and 11 from the 2002 outbreak. Lesions typical of acute fowl cholera were seen in the 1994 outbreak, whereas both acute and chronic fowl cholera occurred in the 2002 outbreak. The isolates were examined in an extended phenotypic typing methodology, by a P. multocida-specific polymerase chain reaction (PCR), by the Heddleston somatic serotyping scheme, and by restriction endonuclease analysis (REA) typing using the enzyme HpaII. All 22 strains had the same phenotypic properties, all were confirmed as P. multocida by PCR, all were Heddleston serovar 4, and all had the same REA pattern. The results indicate that these 2 outbreaks were caused by the same clone of P. multocida--despite the 8-year time period between the outbreaks.     

The Welfare of Laboratory Animals

Veterinary Research Communications -     

Bayesian comparison of test-day models under different assumptions of heterogeneity for the residual variance: the change point technique versus arbitrary intervals

Test‐day milk yields from Spanish Holstein cows were analysed with two random regression models based on Legendre polynomials under two different assumptions of heterogeneity of residual variance which aim to describe the variability of temporary measurement errors along days in milk with a reduced number of parameters, such as (i) the change point identification technique with two unknown change points and (ii) using 10 arbitrary intervals of residual variance. Both implementations were based on a previous study where the trajectory of the residual variance was estimated using 30 intervals. The change point technique has been previously implemented in the analysis of the heterogeneity of the residual variance in the Spanish population, yet no comparisons with other methods have been reported so far. This study aims to compare the change point technique identification versus the use of arbitrary intervals as two possible techniques to deal with the characterization of the residual variance in random regression test‐day models. The Bayes factor and the cross‐validation predictive densities were employed for the model assessment. The two model‐selecting tools revealed a strong consistency between them. Both specifications for the residual variance were close to each other. The 10 intervals modelling showed a slightly better performance probably because the change point function overestimates the residual variance values at the very early lactation.     

No major effect of the leptin gene polymorphism on porcine production traits

Porcine leptin gene (LEP) and its association with production traits was analysed in the Polish Large White (PLW, n = 135), Polish Landrace (PL, n = 120) and synthetic line 990 (L990, n = 184). Two fragments of exon 3 of LEP were studied with the use of RFLP and SSCP techniques. The frequencies of C allele for the T3469C polymorphic site were 0.11, 0.10 and 0.11 in PLW, PL and L990, respectively. Phenotypic data were collected for the average daily weight gain, the feed conversion ratio, the weight of abdominal fat, backfat thickness (five measurements), intramuscular fat, meat content, loin weight, loin muscle area, ham weight and ham cut weight. The contrasts between TT and TC genotypes at the T3469C polymorphic site were estimated in the unitrait Animal Model with genotype at the RYR1 locus included. The lowest p values occurred for association test between T3469C polymorphism and intramuscular fat content in PLW (0.26 ± 0.14%, p = 0.05) and loin weight in L990 (?0.32 ± 0.13 kg, p = 0.01). We conclude that the detected associations are population‐specific and the analysed polymorphism of the LEP gene does not contribute directly to genetic variability of growth and carcass traits in pigs.     

Monitoring of genetic diversity in the Japanese Black cattle population by the use of pedigree information

The gene pool of the Japanese Black cattle has been completely closed to foreign breeds during the last 100 years. Genetic diversity of the Japanese Black cattle from 1960 to 2000 was monitored with three estimates of effective number of ancestors. Founder genome equivalent (N_ge) accounts for all the causes of reduction of diversity. Effective number of founders (N_ef) and non‐founders (N_enf) explain reduced diversity because of unequal genetic contributions of founders and random genetic drift in non‐founders, respectively. Further examination using gene dropping simulation was conducted to obtain information on survival of founder alleles. Unique founder alleles were dropped down along the actual pedigree with Monte Carlo procedure following Mendelian segregation rules, and generated genotypes of all the current live animals (612 959 heads). Pedigree records consisted of 2 075 188 animals was used for these analysis. The estimates of three effective numbers (N_ef, N_ge, and N_enf) decreased from 418.6 to 50.3, 86.6 to 7.3, and 109.2 to 8.5, respectively, during the period 1960–2000. The increasing differences between two kinds of genetic diversity indices derived from N_ge and N_ef showed that large part of the reduced diversity from 1980 was attributed to genetic drift caused by the intensive use of particular limited number of sires. In gene dropping analysis, probabilities of extinction of founder alleles were derived from their distributions of frequency in the current animals. Several founders showed low probabilities of allele extinction, irrespective of their relatively low genetic contributions. This suggests that these founders have lineages through which their alleles are surely transmitted to the current breed. The use of these founders as a strategy for recovering the genetic diversity was discussed.     

Variance component estimation on the frequency of pathologic changes in the navicular bones of Hanoverian Warmblood horses

The results of a standardized radiological examination of 3748 young Hanoverian Warmblood horses selected for sale at auction as riding horses were used to quantify the influence of systematic effects on and to estimate genetic parameters for the prevalence of pathologic changes in the navicular bones. Radiographic findings in the navicular bones of the front limbs were analyzed as all‐or‐none traits. The pathologic changes were mostly classified as slight [PCN(I); 14.9%], less often as moderate [PCN(II); 5.3%] or severe [PCN(III); 1.8%]. Date and year of auction had a significant influence on the prevalence of documented radiographic findings. The prevalence of PCN(I) was further significantly dependent on the examiner, the type and the quality of auction. PCN(II) was significantly more prevalent in male than in female horses. The age, the anticipated suitability and the region of origin of the horses did not have any significant influence on the prevalence of pathologic changes in navicular bones. A higher percentage of genes of the Hanoverian and the Holstein Warmblood horse increased the probability of PCN(I) classification. A significant influence of the sire was found for PCN(I) and PCN(II), and of the male founder for PCN(II) and PCN(III). The female founder was significant only for PCN(II). In general, radiographic findings of any severity in front left and right navicular bones were significantly correlated with each other. Restricted maximum likelihood (REML) was used for the estimation of genetic parameters. The analyses were performed multivariately in linear animal and sire models including height at withers as a separate trait. Heritability estimates for the prevalence of PCN(I), PCN(II) and PCN(III) of horses of both sexes ranged between h² = 0.09 and 0.21. When distinguishing between findings in males and females, somewhat implausible estimates were obtained for PCN(II) in females, which might have been caused by their low prevalence. The additive genetic correlations between the investigated traits indicated that radiographic findings consistent with navicular syndrome have a uniform genetic pattern in males and in females, and irrespective of their severity. However, their genetic correlation to height at withers was found to be inconsistent and, therefore, not to be utilizable for selection.