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This article was published in 1975
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Congenital Polioencephalomyelitis and Hydranencephaly in Cattle.
C.D. Gee, B.V.Sc., Veterinary Inspector, Goulburn.
INTRODUCTION
Periodic epizootics of the congenital arthrogryposis-hydranencephaly complex occur in New South Wales (Blood 1956, Hartley and Wanner 1974). The intervening period between epizootics has been variable with recorded epizootics in 1955, 1960, 1964, 1968 and 1974. Bonner et al. (1961) noted that the epizootic of 1960 was preceded by very heavy rainfall and flooding. Young (1969) observed that the 1968 epizootic was concurrent with an ephemeral fever epizootic but dismissed ephemeral fever as the cause on serological grounds.
FIELD OBSERVATIONS
The observations were made in the south eastern agricultural region of New South Wales. The writer's direct observations were restricted to the Goulburn Pastures Protection District. Information about the rest of the region was obtained from my colleagues (Bonner, R.B., Shepherd, N.C., Timins, G., Jessep, T.M. and Carroll, S.N. - unpublished data).
The south eastern agricultural region comprises the southern coast and the southern highlands together with portion of their western slopes. The coast is mainly a dairying area while the tablelands and slopes are devoted to beef, wool and sheep meat production.
In the 1974 epizootic the first case seen by the writer was on 18 April, 1974 (property A). Two abnormal Hereford calves were presented with a history of three similar calves having already been killed by the owner. One calf (calf 1) had been affected since birth. The general appearance and demeanour of this calf were normal. It could stand or remain standing without assistance. When held to the udder it was able to suck normally.
The other calf (calf 2) had been noted by the owner to be apparently normal for the first three days of life. It was then found on its side with the head twisted underneath. The front legs were completely flaccid and the calf made no attempt to stand when lifted.
Two weeks later a similar picture was seen on another property (property B). Two abnormal Hereford calves were presented. Both calves were perfectly normal in appearance and demeanour. They were bright and alert. Neither could rise to its feet without assistance. When lifted, one calf (calf 1) could not remain standing. If the hindquarters were supported, the calf would move off strongly and purposefully on the front legs.
The other calf (calf 2) could not rise without assistance. When lifted it was able to remain standing but could not walk. The main impediment appeared to be an inability to bring the right hind leg forward.
The features common to properties A and B were that the calves were bright and normal in appearance but with some degree of paralysis.
Both the calves from property A and calf from property B were autopsied. In all cases the brain and spinal cord were macroscopically normal. Brain and cord were preserved in formal saline and forwarded to the Veterinary Research Station at Glenfield for histopathological examination. A consistent picture of polioencephalomyelitis (PE) was seen in all three calves.
The clinico-pathological entity thus established then became common throughout the south eastern region. By 30 June 1974 over 20 confirmed cases of PE had been seen. In some cases there was a degree of flexion and twisting of one or more fetlocks. In July and August at least another twelve confirmed cases of PE were seen. Concurrently cases of hydranencephaly began to be seen in fairly similar numbers. Often both conditions were seen on the one property.
From the end of August onward the PE cases were no longer seen. Many hydranencephaly calves were presented and the occurrence of abnormal calves became almost general. Most larger cattle properties had at least one PE or hydranencephaly calf during the calving season. Finally the occurrence of abnormal calves became so common that owners tended not to report them.
DISCUSSION
In the early stages of the epizootic it was not apparent the PE and hydranencephaly were related. Clinically and pathologically the two conditions appeared to be vastly different. On the one hand we had bright, normal looking calves with variable paralysis and macroscopically normal brain at autopsy. On the other hand we had apparently blind, imbecile calves free of paralysis with gross cerebral abnormality at autopsy.
As the epizootic progressed, the heavy concurrent incidence of the two conditions lead to the hypothesis that they were due to a common cause. The suggestion was that a viraemia in late pregnancy, of low degree or of short duration, could produce a PE calf while the converse could result in hydranencephaly.
In Japan Kurogi et al. (1974) described some inflammatory changes including perivascular cuffing, neuronophagia and gliosis in an arthrogryposis-hydranencephaly epizootic. They observed that these lesions were seen particularly in cases occurring in the early stages of the epizootic. They felt that the nature of the lesions together with the seasonal occurrence and geographical distribution of the cases suggested an infectious agent.
The timing of the postulated wave of viraemia that resulted in the 1974 New South Wales epizootic is of interest. Since calves with hydranencephaly were born up to the end of October, the viraemic episode must have been in progress later than the end of January. Since the first PE case was seen on 18 April 1974, viraemic spread must have been occurring between the beginning of February and the middle of April, 1974. This was a period of high rainfall with the district covered by lush green feed. Surface water was abundant and there were flood rains in April.
SUMMARY
An epizootic of a congenital polioencephalomyelitis-hydranencephaly complex of calves in the south eastern agricultural region of New South Wales in 1974 is described. The polioencephalomyelitis cases prevailed early in the epizootic but were displaced by hydranencephaly cases as the epizootic progressed.
REFERENCES
Blood, D.C. (1956) Aust. Vet. J. 32: 125
Bonner, R.B., Mylrea.,P.J. & Doyle, B.J. (1961) Aust. Vet. J. 37: 160
Hartley, W.J. & Wanner, R.A. (1974) Aust. Vet. J. 50: 185 Kurogi, H., Inaba, Y., Goto, Y., Miura, Y., Takahashi, H., Sato, K., Omori,T., and Matuoto,M. (1974) Arch. ges. Virusforsch (in press)
Young, J.S. (1969) Aust. Vet. J. 45: 574
Figure 1. Polio encephalomyelitis and Hydranencephaly Cases from 1 April 1974 to 30 June 1974.
Figure 2. Polio encephalomyelitis and Hydranencephaly Cases from 1 July 1974 to 31 August 1974 .
