Caprine enterotoxaemia associated with cerebral microangiopathy.

Cerebral microangiopathy is described in naturally occurring clostridial enterotoxaemia in two goats. The two cases were selected from the files of two diagnostic laboratories in Australia, on the basis that the clinical syndrome and history were consistent with a diagnosis of enterotoxaemia, and that the diagnosis was confirmed by the identification of epsilon toxin in the intestinal contents. The lesions consisted of acute perivascular proteinaceous exudate in the brain and bilaterally symmetrical foci of encephalomalacia were observed in one of the goats. These brain lesions confirm that Clostridium perfringens type D enterotoxaemia may produce histologically detectable brain changes in goats.

Streptobacillus moniliformis infection in Swiss white mice.

An epizootic of disease attributed to infection with Streptobacillus moniliformis occurred in a colony of Swiss white mice. The mortality rate among the 180 breeding females in the 6 affected pens was 100%, and most of the sucking young died from starvation. Acute septicemia, subacute septicemia, and polyarthritis were the 3 forms of disease observed. Clinically, septicemic mice either were found dead or were depressed and hunched for 1-2 days prior to death. About a half of these mice had brown skin crusts overlying the mammae. Pathologic findings in cases of acute septicemia were few; in mice with subacute septicemia, there was acute, multifocal, suppurative, embolic interstitial nephritis, and the arthritic form was characterized by many subcutaneous and periarticular abscesses. Severe, acute, diffuse neutrophilic dermatitis was responsible for the brown skin crusts. The S. moniliformis isolate conformed morphologically and physiologically to classical descriptions of the organism. The infection may have gained entry to the colony via wild rats.

Meningoencephalitis and other conditions associated with Histophilus ovis infection in sheep.

Histophilus ovis was isolated from 29 sheep in 20 flocks and 2 artificial insemination (AI) centres in southern New South Wales from 1984 to 1990. The clinical and pathological findings were consistent with previous reports and included polyarthritis (7 flocks), epididymo-orchitis (5), meningoencephalitis (3), pneumonia (3), septicaemia (2), mastitis (1) and metritis (1). Six sheep had meningoencephalitis, a syndrome not previously associated with H ovis infection in sheep, which was similar pathologically to thromboembolic meningoencephalitis in cattle, caused by the related organism, Haemophilus somnus. H ovis was isolated from the semen of 12-month-old rams in a flock that had polyarthritis due to H ovis, in 4-month-old ram lambs and from the uterus of a ewe in a flock that had sporadic cases of H ovis septicaemia.

Anasarca and myopathy in ostrich chicks.

Twenty ostrich chicks that died at, or within, 1 week after hatching were examined from 7 farms with poor (43 to 75%) hatchability. All chicks had anasarca and 15 had mild, generalised, acute degenerative changes in the complexus and pelvic limb muscles. One had fibrinoid degeneration of arterioles. Biochemical examinations produced no evidence of deficiencies of selenium, vitamin A or vitamin E. The syndrome was related to high relative humidity during incubation. Malpositioning also was a cause of embryo mortality.

Yersinia species isolated from sheep with enterocolitis.

In 40 submissions to the Regional Veterinary Laboratory (RVL) Wagga Wagga from sheep in southern New South Wales from 1981 to 1989, 53 isolates of Yersinia sp were recovered from 45 sheep in 37 flocks. Of 53 isolates, 26 were identified as Y. pseudotuberculosis, 20 as Y. enterocolitica, 5 as Y. intermedia and 2 as Y. frederiksenii. Twelve isolates of Y. pseudotuberculosis tested in the slide agglutination test all belonged to serotype III. The 20 Y. enterocolitica isolates were categorised biochemically as biotype 5 strains and, of 6 isolates serotyped, all belonged to serogroup 2,3. Outbreaks of yersiniosis were most common in late winter and early spring and affected flocks often had experienced a change in husbandry. Infection with Yersinia sp was associated with diarrhoea, illthrift and mortality. At necropsy, congestion and occasionally thickening of the intestinal mucosa were observed in affected sheep. Gastrointestinal nematodiasis and coccidiosis often were concurrent findings. The characteristic histological lesion in sheep infected with Y. pseudotuberculosis was acute segmental suppurative erosive enterocolitis. There were no lesions consistently associated with Y. enterocolitica, Y. intermedia or Y. frederiksenii.

Clostridial myocarditis in lambs.

Five outbreaks of myocarditis were investigated in young sheep. They occurred during late winter and spring when there was lush growth of pasture following a prolonged period of drought. Clinically the disease was characterised by sudden death and pathological findings were dominated by acute multifocal locally extensive necrotising and haemorrhagic myocarditis. A fluorescent antibody technique was used to demonstrate the presence of Clostridium chauvoei in paraffin embedded sections of myocardium from 4 of the outbreaks.

Blindness in goats following ingestion of Stypandra glauca.

Twenty-seven of 427 Angora goats of mixed age became blind within a week of consuming large amounts of Stypandra glauca ("nodding blue lily"). A further 200 goats were depressed for several weeks, but most subsequently recovered. Blindness was associated with optic nerve neuropathy which is postulated to have followed compression of the optic nerves within the bony optic canals as a result of severe myelin oedema. Histologically, the intracanalicular portion of the optic nerve was sclerotic, while the intracranial portion of the optic nerve and the optic tracts were degenerating. The retrobulbar portion of the optic nerve was relatively unaffected. In addition, multifocal retinal photoreceptor degeneration was found ophthalmoscopically and histologically. The syndrome was not reproduced during a trial in which 2 goats were fed 4 and 20 kg of S. glauca harvested after it had finished flowering, more than 3 weeks after the first natural cases of blindness. Based on epidemiological and pathological data we propose that S. glauca is toxic to stock, but only for a short period while flowering in spring.

Congenital hydranencephaly and arthrogryposis of Corriedale sheep.

A syndrome of congenital malformations in Corriedale sheep characterised by brachygnathia inferior, campylognathia, tetraemlic arthrogryposis, kyphoscoliosis, hydranencephaly and hypoplasia of the brain stem, cerebellum and spinal cord occurring in various combinations is described. Histologically there was generalised hypomyelinogenesis and hypoplasia of the central nervous system with neurogenic atrophy of skeletal muscle. The syndrome resembled that caused by congenital infection with Akabane virus, however, serological, pathological and epidemiological data indicated that Akabane virus was not involved. The results of a breeding trial suggested that the disorder may be transmitted with an autosomal recessive mode of inheritance.

Dieldrin toxicity in housed merino sheep.

An outbreak of nervous disease with deaths and reproductive failure was investigated in a fully housed flock of 640 super fine wool (Sharlea) Merino sheep. During the 4 months after the flock was dipped in dieldrin, 70 adult sheep died and no live lambs were produced by the ewes. The diagnosis of poisoning with dieldrin was based upon the presence of characteristic clinical signs, pathological findings and the detection of residues of dieldrin in tissues. Deficiency of vitamin A was confirmed in 2 sheep and may have contributed to the reproductive failure.

Examination of rams culled during an ovine brucellosis accredited free flock scheme.

During the early stages of an Ovine Brucellosis Accredited Free Flock Scheme in New South Wales 62 rams were examined to determine the status of their flocks of origin with regard to infection with Brucella ovis. Forty rams were selected because they were either single reactors to low titre or one of a small number of reactors in a B. ovis complement fixation test of the whole ram flock. Twenty two rams were selected because they had palpable abnormalities within the scrotum but were negative serologically. After serological, pathological, bacteriological and histological examinations they were classified in the ensuing categories: 7 positive, 7 inconclusive, 26 false positive and 22 with other lesions. The usefulness of this classification, particularly within the accreditation scheme is discussed.

A syndrome of hepatogenous photosensitisation, resembling geeldikkop, in sheep grazing Tribulus terrestris.

Two outbreaks of photosensitivity disease occurred in weaner sheep in south western New South Wales during early autumn 1982. In each instance there was a history of access to the annual herb, Tribulus terrestris and both the clinical and pathological findings were consistent with geeldikkop, a major disease in the Republic of South Africa. The prevalence rates of clinical cases were 21 and 37%, while the case fatality rates approached 70%. Clinical signs were dominated by jaundice and photosensitisation. Ochre and khaki discolouration were present in the liver and kidneys, respectively. Histopathologically, the most characteristic lesion was the presence of acicular, cholesterol-like clefts in the lumens of bile ducts and in the cytoplasm of hepatocytes and Kupffer cells. Similar structures were also evident in the lumens of nephrons in association with segmental hyperplasia of the neighbouring tubular epithelium. The possible pathogenesis of the hepatogenous photosensitisation and its resemblance to geeldikkop are discussed.

Preweaning mortality in the pig. The prevalence of various causes of preweaning mortality and the importance of some contributory factors.

The relative importance of the various causes of preweaning mortality in the pig was determined from the results of autopsy and laboratory examinations on 718 animals. Conditions associated with parturition accounted for 25.1% of the losses, while physical factors (33.0%), starvation (12.8%) and septicaemia (10.9%) were the most common causes of death in piglets which were born alive. In contrast enteric diseases, viral infections, genetic conditions and various miscellaneous diseases played a relatively minor part. Some biological factors affected the prevalence of the various causes of death. Most losses from physical factors, starvation and septicaemia occurred during the first 4 days of life, while other infectious conditions were more common in older piglets. Large litters at birth had significantly more deaths associated with parturition and due to physical factors and starvation. Increased losses from physical factors occurred in the litters of gilts and sows of parity 5. The size of the enterprise and the use of farrowing crates combined to influence the extent of losses due to physical factors. A significantly higher mortality occurred in the large piggery in which crates were not used. The large units also had fewer deaths resulting from starvation.