Prevalence of caseous lymphadenitis and usage of caseous lymphadenitis vaccines in sheep flocks

OBJECTIVE: To estimate the prevalence of caseous lymphadenitis (CLA), determine the current usage of vaccines against CLA and to measure the effectiveness of these vaccines on sheep farms. DESIGN AND POPULATION: A survey was undertaken on 223 sheep flocks in New South Wales, Victoria and Western Australia. METHOD: The prevalence of CLA was measured by conventional inspection techniques at abattoirs in lines of sheep that could be traced back to a farm. Managers of the flocks were sent a questionnaire about their vaccine practices, management practices and knowledge of CLA. RESULTS: The average prevalence of CLA in adult sheep in these flocks was 26% and varied from 20% in Western Australia to 29% in New South Wales. About 43% of sheep producers used CLA vaccines; only 12% used them as recommended. Awareness of CLA was highest in Western Australia. More producers would use CLA vaccine if they knew the prevalence of CLA in their flock and producers obtained most information about CLA from vaccine resellers. CONCLUSIONS: Only 10 to 15% of producers are currently achieving effective CLA control through the use of recommended CLA vaccination programs. In Western Australian flocks more than 25% of effectively vaccinated ewes will be sent to abattoirs in the 2 to 3 years after this study. However, large decreases in the prevalence of CLA can be achieved by about 70% of producers by either making adjustments to their vaccination programs or buying a vaccine with a CLA component. Two or three key facts on effective CLA vaccination could be made available at the point of sale of vaccines and from abattoirs that reported the prevalence of CLA to farmers.     

Beta2-agonists and cAMP inhibit protein degradation in isolated chick (Gallus domesticus) skeletal muscle

1. The role of beta2-agonist and of cAMP in chick skeletal muscle proteolytic pathways and protein synthesis was investigated using an in vitro preparation that maintains tissue glycogen stores and metabolic activity for several hours. 2. In extensor digitorum longus (EDL) muscle total proteolysis decreased by 15 to 20% in the presence of equimolar concentrations of epinephrine, clenbuterol, a selective hbetaagonist, or dibutyryl-cAMP. Rates of protein synthesis were not altered by clenbuterol or dibutyryl-cAMP. 3. The decrease in the rate of total protein degradation induced by 10(-5)M clenbuterol was paralleled by a 44% reduction in Ca2+-dependent proteolysis, which was prevented by 10(-5)M ICI 118.551, a selective fbeta2antagonist. 4. No change was observed in the activity of the lysosomal, ATP-dependent, and ATP-independent proteolytic systems. Ca2+-dependent proteolytic activity was also reduced by 58% in the presence of 10(-4)M dibutyryl-cAMP or isobutylmethylxanthine. 5. The data suggest that catecholamines exert an inhibitory control of Ca2+-dependent proteolysis in chick skeletal muscle, probably mediated by fbeta2adrenoceptors, with the participation of a cAMP-dependent pathway.     

Slow fiber cluster pattern in pig longissimus thoracis muscle: implications for myogenesis

Recent evidence implicates fiber type proportions as playing a role in meat eating quality, and in pigs it has been suggested that the slow oxidative fibers contribute to both juiciness and tenderness. The fiber distribution in pigs is different from that found in most other species, in which the various types of skeletal muscle fiber are distributed in a "checkerboard" pattern, because in pigs the slow oxidative fibers have a clustered distribution. The initial processes leading to fiber clustering are likely to occur during myogenesis, but the precise mechanistic aetiology of this patterning and whether the slow oxidative fiber clusters occur in a random or ordered fashion is unknown. In the present study longissimus thoracis muscle from Large White crossbred pigs was sampled at the 10th rib, 48 h postmortem. Transverse cryo-sections were cut and histochemically stained to allow the identification of the main muscle fiber types: slow oxidative, fast glycolytic, and fast oxidative glycolytic. Images of the sections were captured and analyzed using point processes and Voronoi Tesselations to examine the randomness and spatial distribution of the clusters of slow oxidative fibers found in pig longissimus thoracis muscle. The results showed that an assumption of complete spatial randomness can be rejected and that a mathematical model incorporating a minimum distance of 1.7 to 2.0 microm between cluster centers produced fiber patterns similar to those observed in the original transverse sections of the muscle. In addition, if it assumed that the central fiber in each cluster is derived from primary myoblast progenitors, these results suggest that there may be some degree of repulsion between the primary fibers during the initial stages of cluster formation. The mechanistic basis of such repulsion is not clear, but it is speculated that secreted factors, such as sonic hedgehog or myostatin may play a role.     

Fleas of elephant shrews (Mammalia, Macroscelididae) and a new host and locality record for Macroscelidopsylla albertyni De Meillon & Marcus, 1958 (Siphonaptera, Chimaeropsyllidae)

Fleas collected from the elephant shrews Elephantulus edwardii (A. Smith, 1839) in the Western Cape Province, Elephantulus myurus Thomas & Schwann, 1906 in Free State Province, and an Elephantulus of undetermined species in the Eastern Cape Province, South Africa are recorded in this paper. Five flea species were recovered of which Demeillonia granti (Rothschild, 1904) was the most numerous and prevalent. It was followed by Macroscelidopsylla albertyni De Meillon & Marcus, 1958, collected only from E. edwardii. Both this elephant shrew and the locality are new records for M. albertyni. Chiastopsylla octavii (Rothschild, 1904), Listropsylla agrippinae (Rothschild, 1904), and a female flea of the Ctenocephalides felis group were accidental infestations. The sex ratio of D. granti was 0.86 on both male and female elephant shrews, while that of M. albertyni on E. edwardii was 0.83.     

Cerebellar cortical abiotrophy in American Staffordshire terriers: clinical and pathological description of 3 cases

Three American Staffordshire Terriers were presented with gait abnormalities and loss of balance at the age of 4.5 (female) and 6 years (2 males). The onset varied between 3 and 5 years of age and the clinical signs were slowly progressive. The neurological examination revealed symmetrical generalized cerebellar ataxia with hypermetria, stiffness, and loss of balance with no evidence of paresis. The menace reflex was decreased in one dog and absent in another. A positional nystagmus was found in two dogs. The dogs were euthanized and a histopathological examination of each brain was performed. Pathological changes were confined to the cerebellum. The main finding was loss of Purkinje cells, as well as depletion of granular cell bodies and shrinkage of the granular and molecular cell layer. These findings are consistent with cerebellar cortical abiotrophy. A genetic basis is supposed, but the mode of inheritance is not determined yet. In contrast to some spinocerebellar ataxias in humans, the cause of Purkinje cell degeneration in cerebellar cortical abiotrophy of dogs is not known.