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This article was published in 1956
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INSTITUTE OF INSPECTORS OF STOCK OF N.S.W. YEAR BOOK.
CONTAGIOUS PUSTULAR DERMATITIS
Two Unusual Outbreaks
J. H. IRVINE, B.V.Sc., Inspector of Stock, Bathurst.
In December, 1955, two unusual outbreaks of Contagious Pustular Dermatitis in sheep were investigated. Both outbreaks were associated with severe lameness, marked loss of condition and, in some cases, some mortality.
CASE 1
This outbreak occurred on a fairly well improved property of 2,000 acres, carrying some 3,000 sheep.
On 14/12/55, this entire flock was put through a plunge dip containing an Aldrin dipping preparation. At the time of dipping, all sheep were in excellent condition and no abnormality or lameness was noticed by the owners.
A few days later it was observed that in a mob of 700 Merino wethers a large proportion was lame. By the 21/12/55, eighty-five (85) per cent. were affected to some degree and many presented a pitiable appearance. A number were down and unable to stand and it seemed that some twelve of these might not survive. Another 300 were barely able to walk and could not be driven. The majority appeared to be in great pain; refusing to eat and spending most of their time in a position of recumbency.
Close examination revealed in some cases the presence of thick scabs completely covering the coronet. These were typical of the lesions sometimes seen in Contagious Pustular Dermatitis. Many others showed some scab formation together with deep fissures in the region of the heels. Others showed a condition resembling Foot Abscess; with swelling above the hoof, sometimes breaking out at the coronet, or extending up the leg. Usually there was little pus present in such swellings. Ulceration in the coronet and heel region was a common feature, lameness was extreme and pain great. Few sheep showed the presence of scabs on their lips and even then these were limited in size and extent. All affected animals showed an appreciable loss of condition.
Scabs were collected and forwarded to the D.V.R., who later was able to advise that a transmission test had confirmed the presence of Contagious Pustular Dermatitis virus in these scabs.
Various treatments, including local applications of solutions of Lysol and Copper Sulphate, Penicillin given intra-muscularly and Sulphamezathine sodium solution subcutaneously, were tried, but these appeared to have little effect in allaying the condition or hastening recovery. However, it is felt that the use of Penicillin and Sulphamezathine may have saved the lives of a number of more serious cases, some of which were in a wretched state; unable or unwilling to rise, in great pain and showing complete inappetence. All told, four (4) deaths were sustained and recovery for the remainder, although uneventful, was prolonged. It took up to eight (8) weeks for lameness to disappear, and at least another four (4) weeks for sheep to regain their lost condition.
Although the entire flock of 3,000 went through the same dip, only one other mob showed any evidence of lameness or any foot lesions, and here symptoms were mild and a few sheep affected.
CASE II.
On the 19/12/55, a flock of 600 sheep was passed through a plunge dip containing B.H.C. The condition of these sheep then was good. On 22/12/55, they were vaccinated against Black Disease and drenched with carbon tetrachloride. Then they were not seen until the 28/12/55, when a large number (approximately forty-five (45) per cent.) in a mob of one hundred and eighty-five merino ewes were found seriously lame and exhibiting symptoms similar to those mentioned in Case 1.
Scabs from the lesions were submitted to Glenfield and once more the D.V.R. was able to advise that a transmission test had confirmed the presence of the virus of Contagious Pustular Dermatitis in the scabs.
Unfortunately, it was not possible to follow this case further due to an apparent lack of interest on the owner's part.
DISCUSSION:
It is obvious that in both cases infection with the virus of Contagious Pustular Dermatitis was the primary cause of the foot lesions and that a secondary infection, which in all probability was mainly responsible for the severity of the lesions and involvement of the deeper tissues of the foot, followed. Whether or not this secondary infection was picked up from the dip is a matter of some conjecture; but it is considered that there is strong evidence in support of this theory. Principally-the high percentage of sheep showing evidence of secondary infection, the correlation between first signs of lameness and proximity to dipping and the almost simultaneous infection by secondary invader organisms of so many sheep.
There appears to be no clear explanation for the low incidence and extreme benignity of the lip lesions in both these cases.
On neither property were thistles thick in the paddocks grazed by the sheep.