von Willebrand's disease in Scottish Terriers in Australia

SUMMARY Over a 5-year period (1988–92), von Willebrand factor antigen (vWf:Ag) assays were performed on plasma samples from 207 Scottish Terriers. Based on these tests, 47 dogs (23%) had vWf:Ag concentrations < 50 canine units (CU)/dL and were classified as heterozygous carriers of the von Willebrand's disease (vWD) gene, while 9 (4%) had concentrations below the sensitivity of the assays and were classified as homozygous. There was thus an overall prevalence of 27% for the vWD gene in the Scottish Terriers tested. The homozygous dogs (median age 0.6 years at diagnosis) consisted of 7 males and 2 females. Eight of these had haemorrhage attributable to the disease, mostly spontaneous and from the oral mucosa. Other signs included haemorrhage induced by trauma or surgery, easy bruising and epistaxis. Many haemorrhagic episodes were severe enough to warrant therapeutic intervention and there was a single fatality. Pedigree analysis, possible in 7 of the dogs, revealed that each was the progeny of a mating between dogs with vWf:Ag concentrations < 50 CU/dL, which supported an autosomal recessive mode of inheritance. A single heterozygous carrier suffered haemorrhage after surgery that, in contrast to the homozygotes, was mild and did not require therapy. The data indicate that vWD is a significant problem in Scottish Terriers in Australia. Accordingly, we recommend that steps be taken to reduce the prevalence of the disease and thereby the number of clinically affected dogs, such as the establishment of a national testing scheme to determine the vWD status of all breeding dogs.     

Effect of desmopressin on plasma factor VIII and von Willebrand factor concentrations in Greyhounds

Objective To determine the effect of 1-Deamino-8-D-argi-nine vasopressin on plasma concentrations of von Willebrand factor and factor VIII in Greyhound blood donors, and to compare the response of 1-Deamino-8-D-arginine vaso-pressin injection on plasma concentrations of von Willebrand factor between groups with different resting plasma concentrations of von Willebrand factor.
Animals Fifteen Greyhound blood donors were used. Dogs were grouped into three categories depending on their von Willebrand factor concentrations.
Procedure Desmopressin was administered subcuta-neously at 1 mg/kg to all dogs. Plasma von Willebrand factor and factor VIII concentrations were measured before and 10, 20, 30, 45, 60, 90 and 120 min after desmopressin injection.
Results The von Willebrand factor and factor VIII concentrations in all dogs increased significantly and remained higher than base-line throughout the 2 h period.
Conclusion Desmopressin is useful in increasing von Willebrand factor concentrations in Greyhound blood donors, including those with low resting concentrations.     

Effect of acepromazine, xylazine and thiopentone on factor VIII activity and von Willebrand factor antigen concentration in dogs

The effect of acepromazine maleate, xylazine and thiopentone on the packed cell volume, plasma protein content, factor VIII activity and von Willebrand factor antigen concentration of blood was studied in normal dogs. The same variables were measured in dogs with haemophilia A given acepromazine maleate and thiopentone. Both the packed cell volume and plasma protein content decreased after the administration of either acepromazine maleate or xylazine. Values were not changed further after administration of thiopentone. Changes in the haemostatic variables measured were generally small. Consequently, blood samples collected from dogs under the influence of premedicant doses of acepromazine maleate or xylazine, and when subsequently anaesthetised with thiopentone, are adequate for the assay of factor VIII activity and von Willebrand factor antigen concentration for establishing an animal's haemophilia A and von Willebrand's disease status.     

Pneumonia in lambs inoculated with Bordetella parapertussis: clinical and pathological studies

Eight one-week-old, colostrum-deprived lambs were inoculated intratracheally with ovine isolates of Bordetella parapertussis. After inoculation, the lambs showed slight depression and anorexia. The total circulating leucocyte counts in these animals rose gradually to a peak five days post-inoculation. Neutrophil counts also increased and were highest at Day 3. Lesions grossly and histologically similar to those of naturally-occurring ovine chronic non-progressive pneumonia were seen in the majority of infected animals. Grossly, they consisted of many small areas of collapse and dull-red consolidation. Histologically, B. parapertussis caused mild acute tracheobronchitis, severe alveolar collapse and acute bronchopneumonia, which was most severe from Days 1 to 3. Pure cultures of B. parapertussis were consistently recovered from nasal swabs of infected lambs throughout the study. Viable bacterial counts of bronchoalveolar lavage fluid showed a rapid elimination of this organism from the lower respiratory tract between Days 1 to 5. Bordetella parapertussis infection in the respiratory tract of lambs has the potential to compromise pulmonary defence mechanisms and allow other pathogenic organisms to become established in the lower respiratory tract.     

Mast cells in the bovine lower respiratory tract: morphology, density and distribution

The lower respiratory tract of six 8-day-old calves and six adult cows was fixed in either isotonic formal-acetic-acid or neutral buffered formalin in order to study the morphology, density and distribution of mast cells. They were found at all levels of the tract with the highest density in the major bronchi. Tissues from cows had significantly more mast cells than those from calves. There were significantly more mast cells detected in calf airways fixed with isotonic formal-acetic-acid compared with those seen in the same tissues fixed with neutral buffered formalin. Regardless of the age and fixation, mast cells were located predominantly in the alveolar septa and in the lamina propria of airways. They were also commonly encountered within the mucosal epithelium of the trachea. Ultrastructurally, mast cells in bovine airways and lung contained two types of intracytoplasmic granules as described in other species.     

Bordetella parapertussis from lambs

Extract

Madam:—An organism identified as Bordetella parapertussis has been isolated in significant numbers from nasal swabs, bronchial washings and the lungs of 6–10 month old lambs showing signs of pneumonia. It has also been isolated from normal lambs but attempts to recover it from adult sheep have so far been unsuccessful (Table I).     

Prevalence and risk factors for medical events following exercise at Australian Greyhound race meetings

Aim

A prospective, observational study to determine the prevalence of post‐exercise conditions at Australian Greyhound race meetings and to assess association with race performance and other environmental, race‐ and dog‐related factors was undertaken.

Methods

A total of 4020 starters were observed (2813 Greyhounds, 1009 trainers, 536 races, 52 race meets, 48 race dates and 11 race tracks) following a race. The presence of diaphragmatic flutter (DF), ataxia, seizure, collapse or sudden death was recorded. Risk factors were screened by univariable logistic regression prior to multivariable backward stepwise model building.

Results

In this study, 962 starters (n = 768 dogs) had DF (23.9%), 16 starters were ataxic (0.4%) and there were no observed cases of collapse, seizure or sudden death. Race track location, increasing race distance, race grade based on increasing 1st place prize value, lower (earlier) race number at the meeting, age, a previous observation of DF at the last start, females, colour (white) and better finishing position were all associated with an increased risk of a Greyhound being observed with DF. However, when logistic regression assessing the random effect of dog was performed, the presence of previous DF was not significant. In this cohort, DF was common following strenuous exercise in Greyhounds and on its own does not appear to result in reduced performance or distress to the animal.

Conclusion

The incidence of ataxia was low and collapse, seizure and sudden death were not observed. However, even though uncommon, ataxia has welfare concerns for racing Greyhounds that warrants further investigation.     

Spontaneous emission spectrum in double quantum dot devices

A double quantum dot device is a tunable two-level system for electronic energy states. A dc electron current was used to directly measure the rates for elastic and inelastic transitions between the two levels. For inelastic transitions, energy is exchanged with bosonic degrees of freedom in the environment. The inelastic transition rates are well described by the Einstein coefficients, relating absorption with stimulated and spontaneous emission. The most effectively coupled bosons in the specific environment of the semiconductor device used here were acoustic phonons. The experiments demonstrate the importance of vacuum fluctuations in the environment for quantum dot devices and potential design constraints for their use for preparing long-lived quantum states.