Congenital hydranencephaly and arthrogryposis of Corriedale sheep

SUMMARY: 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.     

Influence of environmental temperature on experimental infection of redfin perch (Perca fluviatilis) and rainbow trout (Oncorhynchus mykiss) with epizootic haematopoietic necrosis virus, an Australian iridovirus

SUMMARY Experimental transmission of epizootic haematopoietic necrosis virus (EHNV) to adult redfin perch Perca fluviatilis and juvenile rainbow trout Oncorhynchus mykiss was undertaken at different water temperatures using intraperitoneal (IP) and bath inoculation. Redfin perch were highly susceptible to EHNV by both routes of infection. Bath inoculation with as few as 0.08 TCID₅₀. _mL^-1 was lethal. The incubation period in redfin perch was about 11 days at a water temperature of 19–21°C but was longer at colder temperatures and disease did not occur at temperatures below 12°C. The longest incubation period recorded in redfin perch was 28 days. Rainbow trout were not susceptible to infection by bath inoculation but the disease was reproduced after IP inoculation with 10^5.6 TCID₅₀ at water temperatures ranging from 8–21°C. The incubation period was 3–10 days at 19–21°C, but was up to 32 days at 8–10°C. Persistent infection with EHNV was detected by virus isolation in a clinically unaffected rainbow trout after 63 days. The implications of these findings in the understanding of the epidemiology of EHNV infection are discussed.     

Salinomycin poisoning in point-of-lay turkeys

Salinomycin poisoning occurred in a flock of 700 point-of-lay turkeys; 400 birds died over 7 days as a result of consuming feed contaminated with 50 ppm salinomycin. No gross lesions were detected. Histologic evidence of a myopathy was most readily detected in leg muscles of turkeys 5 to 7 d after ingesting salinomycin. Feeding trials were undertaken and individual susceptibility to the drug was found to vary greatly. In affected birds the plasma concentrations of creatine kinase (CK) and aspartate aminotransferase (AST) were found to be in the range of 500,000 to 2,500,000 IU/l and 9000 to 25,000 IU/l, respectively. The marked increase in the plasma activities of these enzymes preceded histological evidence of segmental muscle necrosis.