Continuation of paper on lamb dysentery, published in Handbook of Annual Congress, National Veterinary Medical Association of Great Britain and Ireland, 1928, pp. 55-72 / by T. Dalling.

  • Dalling, Thomas.
Date:
[1928?]
Catalogue details

Licence: In copyright

Credit: Continuation of paper on lamb dysentery, published in Handbook of Annual Congress, National Veterinary Medical Association of Great Britain and Ireland, 1928, pp. 55-72 / by T. Dalling. Source: Wellcome Collection.

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    Reprinted from the Veterinary Record, October 6th, 1928. DISCUSSIONS ON PAPERS PRESENTED TO CONGRESS. No. 2—“ Lamb Dysentery.”* The proceedings of the N.V.M.A. Congress at New¬ castle, on Tuesday, September 4th, 1928, commenced with the discussion of Major Dailing’s paper on “ Lamb Dysentery. ’ ’ The President (Mr. J. W. McIntosh) occupied the Chair and, at the outset, extended a hearty welcome to any new visitors present. The subject the members had before them was one of immense interest to stock-owners and others, especially to those in that district. Before the discussion commenced, however, he would call upon Major Dalling, who wished to supplement his paper. Major Dalling then read the following communication : Continuation of Paper on Lamb Dysentery, published in Handbook of Annual Congress, National Veterinary Medical Association of Great Britain and Ireland, 1928, pp. 55-72. By T. Dalling, M.R.C.V.S., Langley Court, Beckenham, Kent. In the paper referred to above, it was shown that ewes inoculated with antigens prepared from the L.D. bacillus transmitted immunity to their offspring. We have carried out some work recently which has led us to conclude that lambs born from immunised ewes possess no detectable antitoxin at birth and that they receive antitoxin from the mother ewe via the colostrum. In our former experiments we had tested antitoxin from ewes and lambs in the course of our ordinary field work : the ewes had been injected twice before lambing and we felt thaT if we were able to produce more easily detectable immunity in the ewes by hyper-immunising them, we might be able to show definitely how soon after birth lambs showed antitoxin, etc. For this experiment we hyper-immunised a number of ewes by injecting them at intervals during pregnancy with L.D. toxoid until antitoxin was easily detectable in their serum. The ewes were kept under careful observa¬ tion when near lambing, with the result that we were able to see the actual act of parturition and to bleed the lambs before they sucked their mothers. In all, lambs were born from six ewes so treated. With these animals we have carried out a number of experiments ; onR those relating to whether the lamb is born immune or whether it obtains its immunity via the colostrum will be described in this paper. Examination of the Colostrum of Immunised Ewes for the Presence of Antitoxin. Whenever the ewes showed the presence of colostrum in their udders—sometimes several days or even weeks before lambing—a sample was withdrawn and tested for * Paper presented to the National Veterinary Medical Association at Newcastle, September, 1928, by Major T. Dalling, M.R.C.V.S., Becken¬ ham. the presence of L.D. antitoxin. The testing was done by mixing varying amounts of the colostrum diluted in saline with a fixed dose of our test L.D. toxin and, after standing, the various mixtures were injected into mice intravenously. Table 1 is an example of the testing of a sample of colostrum. Table I. The testing of a sample of colostrum for the presence of L.D. antitoxin. (0.1 c.c. of a test L.D. toxin used throughout and mixed with the following amounts of diluted colostrum and injected into mice intravenously after standing at room temperature for about one hour.) Amounts of Colostrum. Results. 0.0035 c.c. + + 0.0040 c.c. + + 0.0050 c.c. + L 0.0060 c.c. L L 0.0070 c.c. L L + = mouse died. L = mouse lived. We have shown that the colostrum from immunised ewes, as soon as it can be withdrawn from the udder contains antitoxin. The amounts vary considerably with the individual sheep. Table II shows the results of testing colostrum from three hyper-immune ewes before lambing. Units of antitoxin in colostrum. 1,400 4,000 660 Table II. Date of Date of testing Ewe. lambing. colostrum. A. 29/6/28 20/6/28 B. 2/7/28 20/6/28 C. 20/7/28 16/7/28 A further sample of colostrum was taken from every ewe within one hour after lambing and before the lamb was allowed to suck. At the same time a sample of serum was taken from the ewe. Tests were carried out for the presence of L.D. antitoxin in both, and a comparison be¬ tween the amount of antitoxin in the colostrum and that in the serum at the time of lambing shows that there is considerably more antitoxin present in the same volume of colostrum than of serum. Table III shows this comparison in four ewes. Table III. Antitoxin content Antitoxin content Ewe. of colostrum. of ewe’s serum. A. 500 250 B. 2,660 660 C. 660 220 D. 2,800 800 After the lambs had sucked and at varying intervals, usually of one week, further samples of colostrum were obtained and tests were carried out as above. The results of these tests show that after the lamb had sucked there is an easily detectable drop in the amount of antitoxin con¬ tained in the colostrum followed by a gradual fall.