von Willebrand's disease in Dobermann dogs in Australia

SUMMARY Over a 5-year period (1988–92), von Willebrand factor antigen (vWf:Ag) concentrations were determined on plasma samples from 614 Dobermanns. The vWf:Ag concentration was < 50 canine units (CU)/dL in 373 dogs (61%); these dogs were classified as carriers of the von Willebrand's disease (vWD) gene. In order to identify which dogs were at risk of haemorrhage due to vWD, we determined a cut-off vWf:Ag concentration below which dogs could be considered at risk. This cut-off was chosen in order to minimise the number of dogs genuinely at risk of haemorrhage, being wrongly classified as not at risk. This was done without sacrificing the specificity of the cut-off to any great extent. A vWf:Ag concentration of < 36 CU/dL was empirically chosen as the optimum cut-off concentration. In 282 dogs (76% of the carriers), the vWf:Ag concentration was below this cut-off and these dogs were, thus, classified as being at risk of haemorrhage due to vWD. Haemorrhage attributable to vWD was seen in 107 dogs (29% of the carriers, or 17% of all the dogs). Haemorrhage mostly followed trauma or surgery, but spontaneous genitourinary and gastrointestinal haemorrhages were also frequent. Of these dogs, 92 were of known age, with a median of 3 years, and 102 were of known sex, with 61% being female. In 89 dogs in which the severity of haemorrhage was subjectively assessed, mild and moderate bleeding occurred with similar frequency (48% and 43%, respectively). There were 8 cases of severe haemorrhage, with two deaths. The likelihood of haemorrhage was related to the vWf:Ag concentration: only 8% of 91 dogs with concentrations between 36 and 49 CU/dL had haemorrhage attributable to vWD, but 36% with concentrations < 36 CU/dL did so. Furthermore, dogs with haemorrhage attributable to vWD had significantly (P < 0.001) lower vWf:Ag concentrations (median 12 CU/dL, n = 107) than dogs with no such history (median 30 CU/dL, n = 132). The data indicate that vWD is a significant problem in the Dobermann breed in Australia and we accordingly recommend that steps be taken to reduce its prevalence, such as the establishment of a national testing scheme to determine the vWD status of all dogs used for breeding.     

Respiratory distress syndrome in newborn puppies

A condition causing neonatal mortality in litters of puppies presents all the definitive features of the respiratory distress syndrome as seen in other species such as the horse and man. Histopathology of lung reveals alveolar collapse, distended respiratory bronchioles and in some instances the presence of eosinophilic hyaline membranes. Evidence is presented which indicates that massive phospholipid release from lung tissue is involved in the pathogenesis of the condition. This may be related to extensive damage to great alveolar cells. The exact aetiology of the condition is not known. Résumé. Les auteurs décrivent un syndrome occasionnant une mortalité néonatale des portées de chiots et qui présente toutes les caractéristiques du syndrome de détresse respiratoire observé dans d'autres espèces animales et chez l'homme. L'examen histopathologique des poumons montra un collapsus alvéolaire, une distension des bronchioles et parfois la présence de membranes hyalines éosinophiles. Certains faits montrent qu'une libération massive de phospholipides à partir du tissu pulmonaire est impliquée dans la pathogénie de cette affection, ce qui serait en rapport avec les lésions des grandes cellules alvéolaires; cependant, on ne sait rien de la pathogénie exacte de l'affection. Zusammenfassung. Ein Zustand, der neonatale Mortalität in Würfen von Hunden verursacht, zeigt alle die definitiven Eigenschaften des Atemnotsyndroms bei anderen Spezies wie dem Pferd und dem Menschen. Die Histopathologie der Lunge ergibt kollabierte Alveolen, erweiterte respiratorische Bronchiolen und in manchen Fällen die Anwesenheit eosinophiler hyaliner Membranen. Es werden Tatsachen genannt, die darauf schliessen lassen, dass massive Phospholipid-freisetzungen aus dem Lungengewebe mit der Pathogenese des Zustands zu tun haben. Dies kann zu extensiven Schädigungen grosser Alveolarzellen in Beziehung stehen. Die genaue Ätiologie des Zustands ist nicht bekannt.     

Chondrodystrophy in calves associated with manganese deficiency

A severe congenital chondrodystrophy in Charolais calves is described. Thirty-two calves were born on the same farm with shortened limbs and enlarged joints. Histologically, there was poor cartilage maturation with excessive amounts of rarefied cartilage matrix. There were degenerative changes in the chondrocytes and a severe reduction in the mucopolysaccharide content of all body hyaline cartilage. The cartilage matrix, when examined ultrastructurally, showed loose, disorganised fibres in a rarefied matrix, and extensive vacuolation of the chondrocytes. A low level of manganese was found in the liver of an affected calf. The pregnant cows were fed on apple pulp and corn silage, both of which are low in manganese.     

A presumed inherited spongiform leucoencephalomyelopathy of Romney lambs in New Zealand

This paper records a unique ovine encephalomyelopathy seen on several farms in the Otago Region of New Zealand. It occurred in 2-3 month-old Romney lambs as a rapidly progressive posterior paresis leading to flaccid paralysis. Pathologically, it was characterised by severe spongy vacuolation of white matter in both brain and spinal cord. It is suspected that the condition is inherited.     

Use of the polymerase chain reaction assay for the detection of Mycobacterium avium subspecies paratuberculosis in blood and liver biopsies from experimentally infected sheep

OBJECTIVE: To evaluate a polymerase chain reaction-based assay for the detection of Mycobacterium avium subsp paratuberculosis in blood and liver biopsies from subclinically infected sheep. STUDY DESIGN: A direct PCR assay for the detection of M a paratuberculosis was applied to liver biopsy specimens and to samples of blood that were sequentially collected over 53 weeks from 14 sheep infected experimentally with the organism. RESULTS: Of 117 blood samples from the 14 experimentally infected sheep, two tested positive in the PCR assay. Both positive results were obtained in two subclinically infected sheep that had paratuberculosis later confirmed by histological examination at necropsy. However, the assay failed to detect the target DNA in samples of blood from five other sheep with histologically confirmed paratuberculosis. Similarly, the PCR assay on liver biopsy specimens collected 32 weeks after administration of M a paratuberculosis gave only two positive results, both of which were obtained in sheep with histological evidence of paratuberculosis. CONCLUSIONS: The PCR assay on blood and liver biopsies does not provide a useful method for the diagnosis of M a paratuberculosis infection in subclinically infected sheep.     

Age-related functional changes in the follicle-associated epithelium of the bursa of Fabricius in Shaver Cockerels

A study of the age-related functions of immunologically important components of the bursa of Fabricius in Shaver cockerels showed that endocytosis of carbon particles by the specialised follicle-associated epithelium was at a high level from hatching until 5 weeks of age and thereafter declined until at 18 weeks it could no longer be detected. The follicle-associated epithelium had marked non-specific esterase activity during the first 15 weeks of life as determined by a standard acid alpha-naphthyl acetate esterase method. The absolute weight of the bursa was at a maximum at 9 to 10 weeks. Involution began before 14 weeks and was complete by 22 weeks. The results indicate that the critical period for the bursa in regard to acquiring immunity from either local vaccination or environmental challenge is likely to be within the first five weeks of life.     

Myopathy of dogs resembling white muscle disease of sheep

Automation of the complement fixation test for diagnosing Brucella abortus infection in cattle has allowed this difficult, time-consuming and labour-intensive hut most specific test to he used for large scale serodiagnosis in New Zealand's Brucellosis Eradication Scheme. The automated test has the advantages of eliminating much human error, of improving accuracy and of reducing the costs of labour and reagents.

The Auto-Analyzer performs a warm complement fixation test at a single serum dilution. Each batch of 39 serum samples is compared with a standard positive control serum with a complement fixing antibody activity equivalent to 1/30 of the second International Standard Ani-Brucella abortus Serum. All sera with an antibody level equal to, or greater than, the standard serum are regarded as positive to the test. A titre for serum tested by the automated method is not obtained, and positive sera that prozone strongly may be recorded as negative. Where necessary, the semi-automated microtitre complement fixation test is used to delineate titres and the status of doubtful automated CFT results. The automated and microtitre complement fixation tests use the same reagents; only relative concentrations differ.