EXPERIMENTAL ENCEPHALOMYOCARDITIS VIRUS INFECTION IN CALVES

Nine calves, were inoculated intravenously with the Innisfail strain of encephalomyocarditis (EMC) virus. Apart from a mild fever, no obvious clinical signs were noted. A low titre viraemia was demonstrated in all 5 calves from which blood was collected, and EMC virus was recovered from the myocardium of 3 of 6 calves at 2, 3 and 6 days after inoculation. Virus was not recovered from the central nervous system. No excretion of EMC virus in urine or faeces was detected in 3 calves. Histopathological lesions were present in brain tissue from only 1 calf, destroyed 14 days after inoculation, and in the heart muscle from another calf, destroyed 7 days after inoculation. Macroscopic lesions were not seen in these organs. Both neutralising and haemagglutination-inhibiting antibodies were produced within one week of infection, reached a peak in 3–4 weeks and persisted undiminished until 9 weeks after inoculation. By nitration on Sephadex G 200, it was shown that the early response was due to IgM type antibodies, and these were replaced by IgG antibody. One calf was inoculated intracerebrally with EMC virus. It developed a flaccid posterior paralysis and was destroyed 6 days later. Virus was recovered from the brain and spinal cord, but no significant histopathological lesions were detected in brain or spinal cord from this calf.     

PRENATAL INFECTION WITH FASCIOLA HEPATICA IN CALVES

The livers from 16,776 calves 1 to 3 weeks of age slaughtered at Shepparton abattoirs were examined for gross evidence of infection with Fasciola hepatica. Those livers with thickened bile ducts were examined for the presence of liver fluke by slicing. One hundred and eight F. hepatica were collected from 84 of these livers, giving a minimum prevalence rate of prenatal infection of calves of 0.5%. These results are discussed in context with reports from other countries.     

EXPERIMENTAL SALMONELLA ANATUM INFECTION IN HORSES

SUMMARY Salmonella anatum was given orally to 8 horses on 11 occasions in doses ranging from 9.5 × 10⁶ to 8.8 × 10¹¹ organisms. Four distinct syndromes were induced based upon clinical, laboratory and pathological findings: (1) asymptomatic; (2) moderate clinical signs with or without changes in faecal consistency; (3) fever, depression, anorexia with unstructured or diarrhoeic faeces; and (4) septicaemia with or without diarrhoea, and peripheral circulatory failure. All animals excreted the organism. The peak temperature preceded the onset of diarrhoea by 1 or 2 days. Changes in faecal consistency were associated with direct isolation of the organism. The degree of neutropaenia increased with the dosage. Blood cultures were unsatisfactory, only 1 of 33 samples being positive. The serological responses were not significant although one animal displayed a significant seroconversion consistent with the clinical reaction. Indomethacin was not of value in moderating intestinal fluid secretion in one animal. The distribution and quantitation of positive cultures at autopsy closely reflected the type of syndrome induced. The invasiveness of the organism was confirmed by frequent direct recoveries from intestinal wall and draining lymph node samples. S. anatum appears to be of similar pathogenicity to S. typhimurium in the horse, at least under experimental conditions.     

水牛犊人工感染牛巴贝斯虫试验

利用从牛巴贝斯虫病症区采集的镰形扇头蜱叮咬和皮下接种液氨保存的含虫血两种方法，感染去脾和未去脾犊牛，证实了牛巴贝斯虫可以感染水牛犊并使去脾水牛犊发病，但不能使未去脾水牛犊发病。连续注射氢化泼尼松可收提高去脾水牛犊的红细胞染虫率。本试验还详细观察和探讨了水牛巴贝斯虫病的临床症状、虫体在病牛血液中的消长规律、血液学变化及病理解剖学变化。     

CAMBENDAZOLE TOXICITY IN CALVES

The death of 3 of 8 dairy calves was associated with the administration of 98.5 mg/kg cambendazole. Significant lesions consisted of marked pleural effusion, severe pulmonary oedema and necrotic lymphadenopathy.