Prophylaxis of lamb dysentery / by T. Dalling, J.H. Mason, and W.S. Gordon.

  • Dalling, Thomas.
Date:
[1927?]
Catalogue details

Licence: In copyright

Credit: Prophylaxis of lamb dysentery / by T. Dalling, J.H. Mason, and W.S. Gordon. Source: Wellcome Collection.

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    Reprinted from “ The Journal, of Comparative Pathology and Therapeutics. po/. XL.—Part 3. September, 1927. PROPHYLAXIS OF LAMB DYSENTERY. By T. Dalling, J. H. Mason, and W. S. Gordon, Wellcome Physiological Research Laboratories, Beckenham, Kent. The Use of Vaccine on Ewes. The results of the vaccination of ewes with the object of protecting their offspring against Lamb Dysentery were recorded in 1926 (1). During the past lambing season we carried out further observations in Scotland, Northumberland, and Wales. In the 1926 experiments inoculating ewes in autumn and again in spring gave the best results, and this method of inoculation was used in all the 1927 experiments. The vaccine used in most cases was, as already recorded, a neutralised toxin-antitoxin made from the special type of a B. welchiiAJke organism isolated from tissues of affected lambs, and a killed suspension of many strains of B. coli also isolated from lambs sick of the disease. Inoculations were carried out in September or October and again in March or April. In the 1926 season injections were made subcutaneously in the thigh. Because of the degree of lameness produced in pregnant ewes by this method, we adopted a new method of inoculation for the past season’s work. The under surface of the tail was chosen as a suitable site, and, with careful manipulation, vaccine can be injected there in the desired amount without causing any inconvenience to the sheep. At first it was thought advisable to “ turn up ” the sheep, but latterly we have been able to carry out inoculations into the tail with the ewes held in the normal standing position. No general systemic disturbance was noted after the autumn inoculations ; and in the spring, on the majority of farms, the same held good. In Northumber¬ land, however, of 14,420 ewes inoculated, 23 died within 48 hours after the operation. We are still at a loss to account for these deaths among ewes. There is apparently no local infection ; the site of inoculation shows no lesions, and the administration of a homologous serum to ewes showing the first signs of illness after inoculation is without effect. (Vaccine from bottles actually used for inoculation has proved sterile on laboratory tests). We are of opinion that the handling of pregnant ewes must be carried out with the utmost care, as several farmers have volunteered the information that the mere “ gathering ” of flocks of pregnant ewes and their herding in sheep pens is often attended by several deaths. Results in Scotland. In the South of Scotland, over an area of about 1,200 sq. miles, 4,015 ewes were inoculated, while 2,137 were left untreated as controls. The inoculated and control ewes were from the same “ cuts ” of sheep on the same “ hirsels ” of the same farms, and no selection was made in any way. During the whole of the lambing period one of us (W.S.G.), visited the various farms at regular intervals, and carried out post¬ mortem work on almost every lamb dead from any cause whatever, including those “ still born.”
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