Fibrinous pericarditis and cardiac tamponade in a 3‐week‐old pony foal

A 3‐week‐old Pony of the Americas foal presented with a history of respiratory distress presumed to result from Actinobacillus equuli pleuropneumonia and septic arthritis. Failure of transfer of passive colostral immunity was suspected, but not confirmed, based on a history of the foal being separated from its dam shortly after parturition. Transient improvement was noted following thoracocentesis and removal of approximately 600 ml of pleural fluid but progressive clinical signs of congestive heart failure developed. Fibrinous pericarditis with evidence of cardiac tamponade was subsequently diagnosed via thoracic ultrasonography. Early clinical signs of cardiogenic shock were identified and fibrinopurulent exudate removed through a catheter placed with ultrasound guidance into the pericardium. The foal experienced cardiorespiratory arrest during the procedure and died despite resuscitative efforts. Post mortem examination identified extensive hypertrophy of the pericardium, septic arthritis, mild pleural effusion and focal bronchopneumonia. This report details the clinical evaluation, haematology, treatment and post mortem pathology of a foal with Actinobacillus equuli associated fibrinous pericarditis, as well as a brief review of cardiac tamponade.     

Comparative effects of annual and permanent dairy pastures on soil physical properties in the Tsitsikamma region of South Africa

Abstract. The effects of grazed, annual ryegrass pasture (annually tilled with a rotary cultivator) and permanent kikuyu pasture were compared with that of undisturbed native vegetation at four sites in the Tsitsikamma region, South Africa. Soil organic carbon content, aggregate stability, saturated hydraulic conductivity, air permeability, root length density and rooting depth were all less under ryegrass than kikuyu pasture. There was, however, no consistent effect of pasture-type on pore size distribution or penetrometer resistance. Differences in penetrometer resistance were most obvious in the 10–30 cm layer with subsurface compaction being evident at some sites under both types of pasture. This was attributed to the treading effects of grazing cattle plus formation of a compacted layer at the depth of tillage under ryegrass pastures. Subsoil tillage of a ryegrass pasture resulted in a substantial reduction in penetrometer resistance in the compacted 10–20 cm layer and increases in hydraulic conductivity, air permeability, root length density and rooting depth. We conclude that conversion from conventional to zero tillage is a potential way of improving the sustainability of annual pasture production and that the extent of subsoil compaction under both pasture types needs further investigation.     

An economic evaluation of consumer characteristics affecting fresh potato consumption

The purpose of this report was to relate several economic and social characteristics of consumers to level of fresh potato consumption. National cross-sectional data were used to identify consumption patterns using the least squares regression procedure. Relationships were estimated for white and nonwhite households The relationships for white households indicated that price of fresh potatoes, family income, number of meals eaten-at-home, family size, and expenditures for sweet potatoes were important determinants of weekly fresh potato consumption. Regional, urbanization and seasonal differences were also apparent for white households. Age and expenditures for processed white potatoes were less critical in determining consumption patterns The relationship for the nonwhite households was similar structurally to the white household relationship in many respects. Actually, age, expenditures for sweet potatoes and processed white potatoes and a couple of shift variables were the only ones which did not exhibit statistically significant coefficients. Seasonal and regional differences were noted.     

The effect of fertility control on the transmission of bovine tuberculosis in wild brushtail possums

AIM: To determine the effect of fertility control on the rate of transmission of bovine tuberculosis (Tb), caused by Mycobacterium bovis, in brushtail possums (Trichosurus vulpecula).

METHODS: At two study sites with a history of Tb infection in the resident possum population, a sample of adult male and female possums (n=50), determined by palpation to be Tb-free, was surgically sterilised by gonadectomy. A sample of untreated Tb-free male and female possums (n=54) served as controls. Each study site was trapped every 2 months over a 3-year period, and the Tb status of the individuals in the trial assessed. At the conclusion of the trial, all remaining experimental individuals were killed, necropsied and examined for characteristic lesions typical of Tb. The rate of transmission of Tb infection was estimated using the incidence of tuberculous cases in the experimental animals and comparing it between sites, sex and sterilisation treatment.

RESULTS: Sterilisation by gonadectomy resulted in a reduction in the rate of transmission of Tb in male possums by 53%, but a corresponding increase in sterilised females for reasons that are still unclear. However, this interaction was statistically weak (p=0.10). When the sexes were combined, there was no overall effect of sterilisation on the rate of transmission of Tb (p=0.43). Sterility treatment notwithstanding, there was a highly significant difference in the rate of transmission between the sexes (p=0.01), being almost one order of magnitude higher in untreated males compared with untreated females.

CONCLUSIONS: Although lacking strong statistical support, these results suggest that fertility control that targets endocrine control of fertility may provide some additional benefits for disease control over that achieved by reductions in population density, by reducing the rate of transmission of M. bovis in male possums. However, additional studies are needed to confirm the validity of these results. The large difference in the rate of transmission of M. bovis in untreated males compared with untreated females suggests that transmission of Tb among males may be an important driver of the dynamics of Tb infection in possums.     

Cryopreservation of Piau‐Breed Wild Boar Sperm: Assessment of Cooling Curves and Centrifugation Regimes

This study aimed to assess the effects of different cooling curves and centrifugation regimes used in cryopreservation protocols on the post‐thaw viability of Piau‐breed wild boar (Sus scrofa) sperm using in vitro assessment tests. Two centrifugations (800  g for 10 min and 2400  g for 3 min) and two cooling curves (conventional cooling using nitrogen vapour – freezing 1 and automated cooling using a programmed freezing machine – freezing 2) were tested. Therefore, the treatments were divided into M3 – centrifugation at 2400  g for 3 min and freezing 2; M10 – centrifugation at 800  g for 10 min and freezing 2; R3 – centrifugation at 2400  g for 3 min and freezing 1; and R10 – centrifugation at 800  g for 10 min and freezing 1. No significant differences (p > 0.05) between treatments occurred post‐thawing regarding the total sperm motility means recorded. The mean values of the different treatments were not different from each other regarding the supravital staining (SV), hypo‐osmotic test (HO), sperm–egg binding assay or sperm morphology. This study showed that both the cooling curve and the centrifugation regime affected the quality of post‐thaw sperm, and centrifugation for shorter times and cooling curves using automated cooling are the most suitable for minimizing sperm injury.     

Phenotypic stability of resistance to late blight in potato clones evaluated at eight sites in the United States

Changes in the fungal pathogenPhytophthora infestans in the United States pose a significant threat to potato production. Sources of resistance to these new genotypes of P.infestans need to be identified for potato breeders to have parental materials for crossing, and the phenotypic stability of late blight resistance in these potato clones needs to be determined. Sixteen potato clones which reportedly have some resistance to late blight were evaluated at eight locations: Florida (FL), Maine (ME), Michigan (MI), Minnesota (MN), North Dakota (ND), New York (NY), Pennsylvania (PA) and Wisconsin (WI) in 1996. Percent infected foliage was recorded at approximately weekly intervals following the onset of the disease at each location. Area under the disease progress curve (AUDPC) was calculated. Clones were ranked for mean AUDPC within location and the nonparametric stability statistics, mean absolute rank differences and variance of the ranks, were analyzed for phenotypic stability. Neither of these statistics was significant, indicating a lack of genotype x environment interaction on the rankings of these clones across locations in 1996. The four clones with lowest AUDPC scores were U.S. clones AWN86514-2, B0692-4, B0718-3 and B0767-2. These clones should be useful parental materials for breeders seeking to incorporate genes for late blight resistance into potatoes.     

Infectivity of Cryptosporidium sp isolated from wild mice for calves and mice

A study was conducted to determine the incidence of cryptosporidiosis in wild mice (Mus musculus) and the infectivity of oocysts from their feces for susceptible calves. The presence of oocysts and the duration of shedding of oocysts in the feces were evaluated in 115 wild mice. Approximately 30% of the mice shed Cryptosporidium sp oocysts, without evidence of clinical infection; recurrence of oocyst shedding was found in about 50% of the mice. Oocysts from the feces of naturally infected mice were infective for calves and mice. Calves began shedding oocysts at 7 days and shed oocysts for about 10 days. Nonfatal, clinical cryptosporidiosis developed in 7 infected calves. The mice began shedding oocysts at 6 days and shed oocysts for 12 days. Fatalities or clinical infection did not develop in 5 infected mice. The results indicated that Cryptosporidium-infected wild mice may be a source of cryptosporidiosis in susceptible calves.