Naphthalophos combinations with benzimidazoles or levamisole as effective anthelmintics for sheep.

OBJECTIVE: To investigate the relative efficacy and safety of the anthelmintic naphthalophos in sheep, either given alone or in combination with benzimidazole (fenbendazole and albendazole) or levamisole anthelmintics. DESIGN: A parasitological study using faecal egg count reduction tests, a validating slaughter trial and field safety trials. PROCEDURE: Faecal egg count reduction tests were carried out on 13 farms. Naphthalophos and combinations of naphthalophos with levamisole and fenbendazole were included in the drench tests. On one property a controlled efficacy study was carried out to validate faecal egg count reduction test findings. In this trial, sheep were slaughtered 10 days after treatment and the remaining parasites recovered from the gastro-intestinal tract. Safety trials were carried out on eight farms where approximately 50,000 sheep were treated with naphthalophos and albendazole that were tank mixed in the backpack. RESULTS: The efficacy of naphthalophos alone in faecal egg count reduction tests ranged from 59 to 98% with one test showing > or = 95% reduction. The efficacy of naphthalophos and levamisole ranged from 74 to 100%, with 5 farms showing > or = 95% reduction. The efficacy of naphthalophos and fenbendazole ranged between 88 and 100% with > or = 95% reduction achieved on 10 farms. The controlled efficacy study showed a good correlation between the faecal egg count reduction tests and numbers of parasites recovered, except for Nematodirus where the faecal egg count reduction test overestimated efficacy. The mortality rate in the safety trials was 0.05%, with most fatalities occurring on one farm. CONCLUSION: The combination of naphthalophos and fenbendazole was more effective than a combination of naphthalophos and levamisole, and will provide a sufficiently safe drench rotation option.

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.

A viral infection causing cytomegalic inclusion disease in the renal epithelium of the platypus (Ornithorhynchus anatinus).

Cytomegaly and intranuclear inclusion bodies were observed in the renal collecting duct epithelium in three of four wild caught platypuses (Ornithorhynchus anatinus) from New South Wales using light and electron microscopy during routine pathological studies. Non-enveloped, spherical virions measuring about 80 nm in diameter were present in the nucleus and cytoplasm of affected cells as well as in the lumen of the renal tubule. A single enveloped virion measuring about 150 nm in diameter was found. There was no serological evidence of infection with cytomegalovirus (AD169 antigen) or adenovirus (mammalian and avian group antigens) in any of the platypuses. Although the identity of the virus was not confirmed, it was probably an adenovirus based on morphological grounds. The infection appeared to have little effect on the host.

Evaluation of three LPS-specific monoclonal antibodies for the immunodiagnosis of bovine brucellosis.

Bovine sera collected during the Australian brucellosis eradication campaign were used to assess the value of three monoclonal antibodies (MAb Bruce 1, 4 and 7) for the immunodiagnosis of bovine brucellosis in a competitive enzyme immunoassay (CEIA). Each MAb reacted to a different epitope of lipopolysaccharide molecules on the cell surface of Brucella abortus. When the sensitivity of the CEIA was set at 100 per cent so that all infected animals were identified, the specificity of the test using MAb Bruce 1 and Bruce 7 was 69 per cent and 52 per cent, respectively. On the other hand, a quarter of the sera from infected cattle did not inhibit the binding of MAb Bruce 4 to the antigen. With a maximum sensitivity of 75 per cent, the specificity of the CEIA using MAb Bruce 4 was 94 per cent. However, all three MAb cross reacted with sera from sheep infected with Bovis, Histophilus ovis and Actinobacillus seminis.

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.

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.

Sensitivity and specificity of two microtitre complement fixation tests for the diagnosis of Brucella ovis infection in rams.

An investigation was made into microtitre complement fixation test (CFT) procedures suitable for the serological diagnosis of naturally occurring Brucella ovis infection in rams. A procedure similar to the Australian standard procedure for bovine brucellosis was unsatisfactory when applied to sheep. Modification of the procedure by use of an initial serum and anticomplementary control dilution of 1:8 and increasing complement fixation time to 60 minutes at 37 degrees C, greatly improved the efficiency of the test. A sensitivity of 100% was recorded for 59 serums from known infected rams and a specificity of 99.9% for 1593 serums from rams known or believed to be free of infection. Some aspects of applying CF tests to sheep serums are discussed.