Evaluation of the response to an accelerated immunisation schedule using a canarypox-vectored equine influenza vaccine, shortened interdose intervals and vaccination of young foals

The results of an accelerated immunisation schedule for horses used as part of the emergency response plan to contain and eradicate equine influenza in Australia in 2007 is described. The horses studied were vaccinated with a recombinant canarypox-vectored vaccine (ProteqFlu?, Merial) with a shorter interdose interval. Vaccinated horses included foals aged less than 4 months.     

MEASUREMENT OF BODY COMPOSITION IN CATS USING COMPUTED TOMOGRAPHY AND DUAL ENERGY X‐RAY ABSORPTIOMETRY

Dual energy X‐ray absorptiometry (DEXA) is a reference method for assessing body composition but is seldom `accessible in veterinary settings. Computed tomography (CT) can provide similar body composition estimates and we propose that it can be used in body composition studies in animals. We compared CT and DEXA data from 73 healthy adult neutered domestic cats. Three approaches for measuring adipose tissue percentage from full‐body CT scans were explored. By examining the frequency distribution of voxels by Hounsfield unit (HU) value, it is possible to calculate a fat index (Fat%) that is in close agreement with the fat percentages obtained from DEXA scans. Fat% values obtained by the best of the methods had a mean difference of 0.96% (95% confidence interval 0.33–1.59%) from the DEXA results. Fat% obtained by the other two methods were characterized by good correlation but poor agreement and in one of the methods, the difference between the values from the two modalities was proportional to their mean. By using CT, it is possible to obtain body composition estimates that are in close agreement with those available using DEXA. While the significance of individual Fat% measurements obtained from CT can be difficult to interpret and to compare between centers, CT can contribute to research studies concerned either with nutrition or with obesity‐related disorders.     

STARRY SKY HEPATIC ULTRASONOGRAPHIC PATTERN IN HORSES

The starry sky hepatic pattern is an unusual ultrasonographic appearance of equine liver characterized by numerous small, hyperechoic foci, some of which cast an acoustic shadow, distributed randomly throughout the hepatic parenchyma. Our objectives were to describe the signalment, clinical signs, clinicopathological findings, primary disease process, and ultrasonographic findings of horses with this ultrasonographic pattern, as well as determine the associated gross and histologic changes. The starry sky pattern was identified in 18 adult horses of mixed gender and breed. The horses had various clinical signs, with weight loss and anorexia reported most commonly. Liver size and parenchymal echogenicity were normal in most horses. The hyperechoic foci frequently caused acoustic shadowing. Biliary dilation was noted rarely. The ultrasonographic pattern was the result of numerous fibrosing hepatic granulomas in all horses evaluated histologically. γ‐Glutamyltransferase was the most commonly elevated hepatic enzyme, though it was increased in fewer than half the horses. Fifteen horses had an additional disease that was identified as the apparent cause of clinical signs. Three horses had primary hepatic disease while 12 had diseases of other body systems. Therefore, the starry sky ultrasonographic pattern is likely incidental in most horses and not clinically significant. Improved recognition of this pattern and further investigation of affected horses may help refine the etiology and clinical significance of the granulomas.     

Grazing Management in Tropical Savannas: Utilization and Rest Strategies to Manipulate Rangeland Condition

Grazing management is important for sustaining the productivity and health of rangelands. However, the effects of grazing management on herbage growth and species composition in the tropical savannas of northern Australia are not well known. In this eight-year study the influences of utilization rate and resting pastures from grazing on vegetation dynamics were measured at three sites in northeast Queensland, Australia. The sites had high, medium, and low soil fertility, and there were two land condition classes (States I and II) at each site. Severe drought occurred during the first four years, but above-average rainfall was received in the second half of the study. High utilization rates reduced biomass, perennial grass basal area, and ground cover. The reduction in biomass was due to both higher consumption and decreased primary production. State I condition plots at the high and medium soil fertility sites were initially dominated by decreaser perennial grasses, but these declined at all utilization levels, particularly the high rate. They were largely replaced by exotic perennial grasses. At the low fertility site there were no exotic grasses, and the decreaser grasses increased in all treatments, with the increases greatest in plots with low utilization or medium utilization plus resting. In the State II condition plots at the high and medium fertility sites, low or moderate utilization, led to an increase in both decreaser and exotic perennial grasses; with high utilization the decreaser perennial grasses declined and were replaced largely by exotic perennial grasses. This study clearly demonstrated that either conservative stocking with year-round grazing or a grazing system that includes some wet-season resting will help maintain land in a desirable state or help facilitate the transition from a less desirable ecological state to one more desirable for pastoral production and rangeland condition.     

Effects of sex and age on genotype x environment interaction for beef cattle body weight studied using reaction norm models

The interest in the effect of genotype × environment interaction is increasing because animal breeding programs have become geographically broader. Climate changes in the next decades are also expected to challenge the present breeding goals, increasing the importance of environmental sensitivity. The aim of this work was to analyze genotype × environment interaction effect on cattle BW using the environmental sensitivity predicted by random regression reaction norm models, including sex and age effects as additional dimensions in the study. Genetic parameters were estimated for adjusted BW of Brazilian Nelore cattle at different ages (120, 210, 365, and 450 d), using linear polynomials for random regression analysis. The analyses with sex as a fixed effect (total analyses) were compared with those with sex-separated progenies (male and female progeny analyses, respectively). (Co)variance components were estimated and breeding values calculated EPD. The results showed important differences in reaction norm model genetic parameter estimates according to different age and sex analyses. The results confirmed the presence of an important genotype × environment × sex × age interaction for Nelore cattle BW. The patterns in these results lead to a revision of the importance of sexual and developmental factors on plasticity and adaptation concepts.     

Evaluation of the agar-gel immunodiffusion test in the diagnosis of canine blastomycosis

The agar-gel immunodiffusion test was used to evaluated 35 dogs with histopathologically confirmed blastomycosis and 98 dogs without blastomycosis. The test had a sensitivity of 91% and a specificity of 96%. Thirteen of the dogs treated for blastomycosis were tested at 6 to 33 months after treatment with amphotericin B. Ten of 13 dogs became seronegative and 3, though clinically normal, remained seropositive at 19, 20, and 20 months, respectively, after amphotericin treatment.     

PORTAL VEIN ANOMALY AND HEPATIC ENCEPHALOPATHY IN THREE DOGS

SUMMARY Portal vein anomaly and associated hepatic encephalopathy was diagnosed in three dogs; a 2-year-old Old English Sheep Dog, a 14-week-old Old English Sheep Dog and a 20-week-old Corgi. The common clinical changes were anorexia, vomiting, depression, weakness and ataxia. The major laboratory findings were an elevated serum alanine amino transferase activity, hypoproteinaemia, hypoalbuminaemia, prolonged retention of sulphobromophthalein, fasting and postprandial hypeoammonaemia and ammonium biurate crystalluria. Angiographic studies demonstrated the presence of a patent ductus venosus in each case. The 2 Old English Sheep Dogs were destroyed at the owners' request and the necropsy findings in each case verified the presence of a portacaval shunt and hepatic encephalopathy. The Corgi is still alive, with conservative medical management, 28 months after the onset of signs. The dog is stunted and has mild, intermittent neurological disturbances. Clinical biochemistry indicates severe hepatic insufficiency and suggests a poor long term prognosis.