VACCINATION OF EWES AGAINST “PULPY KIDNEY” (INFECTIOUS ENTEROTOXAEMIA) IN LAMBS.

New Zealand Journal of Agriculture, Volume 54, Issue 2, 20 February 1937, Page 65

VACCINATION OF EWES AGAINST “PULPY KIDNEY” (INFECTIOUS ENTEROTOXAEMIA) IN LAMBS.

FURTHER TRIALS IN OTAGO AND SOUTHLAND, SEASON 1936.

C. V. Dayus,

District Superintendent, Department of Agriculture, Dunedin.

In the May, 1936, issue of the N.Z. Journal of Agriculture, a summary of the results of the experimental work carried out in Central Otago in the 1935 season was given. ’ This consisted in the vaccination of ewes with a formalized enterotoxaemia (clostridium Welchii, Type D) vaccine, with the object of transferring antitoxic immunity from the ewe to the lamb. Reference to this article will show that the results obtained justified the trials, and there appeared to be encouraging support to the possibility of the successful vaccination of ewes under practical conditions in the field as a means of minimizing the losses from pulpy kidney in lambs. • ■ # These field results were further supported by work which had been undertaken in Australia, the results of which were published by D. T. Oxer in the April, 1936, issue of the Australian Veterinary Journal. It was clearly demonstrated, by careful laboratory technique, that the usual prophylactic vaccination of ewes against enterotoxaemia is followed in most-cases by a marked response, as judged by the antitoxic titre of the blood serum, but it was 'found that there is considerable variation in . the response of different individuals. Also, that the antitoxic immunity developed by the ewe is transmitted to the lamb . via the colostrum (first milk). ■ Oxer concludes, “ We are unable to say what degree of immunity would have to be acquired by the lamb before it was protected from the natural infection. It appears probable, however, that a large percentage of lambs would be protected during the first three weeks of life, although it is realized that' this can only be determined satisfactorily by extensive trials in the field.” , Herein are recorded the results of further vaccination trials which have been carried out in the field in various parts of Otago and Southland during the 1936 season. .. In all, 2,608 ewes were vaccinated with a vaccine prepared at the Department’s Veterinary Laboratory, Wallaceville. In addition,

observations were maintained on a group of 1,141 ewes which were vaccinated by farmers, in some cases with our help, with a commercial enterotoxeemia vaccine purchased from the Commonwealth Serum Laboratories, Royal Park, Victoria. In the former case the first dose of vaccine (5 c.c.) was given approximately six weeks before lambing and the second dose (10 c.c.) approximately ten days before lambing. In the latter case the dose recommended for the first vaccination was 3 c.c., followed by a second dose of 7 c.c. four weeks later. Owing to the fact that the vaccine was not procured in time the four-week interval was not strictly followed, and probably insufficient time elapsed between the second dose and the commencement of lambing. In all cases a suitable number of control ewes were reserved, which, with the vaccinated ewes, were depastured together. The particulars are given in the following tables :

In the vaccinated group of ewes the pulpy kidney losses among lambs were 8 = 0-306 per cent. In the control group of ewes the pulpy kidney losses among lambs were 84 = 3-36 per cent.

In the vaccinated group of ewes the pulpy kidney losses among lambs were 22 1-92 per cent. ' . ■ . In the control group of ewes the pulpy, kidney losses among lamb were 84 = 3-68 per cent. ' Technique of Vaccination. The most suitable place to handle the ewes for vaccination is in a drafting-race, into which the ewes are run, filling the race without unnecessarily crushing the sheep. Vaccination is then commenced,, and the operator and his assistant work along the whole race, leaning over from outside the race. The site of injection found suitable is behind the shoulder ; this allows the minimum of handling, the ewes standing on all four limbs practically unrestrained. The wool behind the shoulder and the site of injection is thus exposed for the operator ; this is quickly cleansed with a swab of cotton-wool soaked in methylated spirit. A 20 c.c. Record hypodermic syringe is used, for the injection, and the needle is inserted obliquely, keeping the barrel of the syringe more or less parallel to the body, of the ewe, through the skin and the subcutaneous fascia, then the required dose is introduced subcutaneously by pressure on the plunger , of the syringe. . At the commencement of the work the syringe is sterilized by boiling. It is important to remove the plunger from the barrel of the syringe. The portions are then placed in the cold water, which is brought to the boil and retained so for ten minutes.. The needles are kept handy in a suitable vessel containing methylated spirit. The vaccine is kept in its original container, the cork being removed and a piece of sterlized rubber tied over the opening through this the needle of the syringe is inserted to draw off the vaccine. The surface of this rubber top can be kept clean by wiping with a cotton-wool swab soaked in methylated spirit prior to each refill. By this procedure the vaccine is maintained free of extraneous contamination . during the course of the operation.

After completing the number of sheep in the race, the syringe and needle are rinsed out with two charges of methylated spirit; in the meantime the next lot of ewes are being driven into the race.

The vaccine in the container should be used up in one day so as to avoid any quantity being held over for use once the container has been opened. The vaccine in the unopened containers should be stored in a ■cool dark place until required for use.

Under the conditions outlined no untoward happening has followed vaccination, nor has any harmful result followed the handling of ewes in this manner comparatively close up. to lambing. Another method has been described in Australia, where vaccination has been done inside the thigh or alternatively inside the arm ; either seems unnecessarily laborious, as the sheep have to be handled individually and held up in a sitting position on the rumpan undesirable procedure in the case of ewes advanced in pregnancy. ■ Conclusion. \ The results of the trials carried out in the 1936 season lend further support to the possibility of reducing the mortality in lambs from pulpy kidney by vaccination of the pregnant ewe. The percentage loss in the vaccinated group in 1935 was 0’24 per cent., as against 0-306 per cent, in 1936. The percentage loss in the control group in 1935 was 7-02 per cent., as against 3-36 per cent, in 1936. There is a slight increase in the vaccinated group of only 0-066 per cent. ; the variation in the response of different individuals to vaccination may possibly account for this. The losses in the control group are considerably down ; this is in keeping with the general position in thedistrict. Losses from pulpy kidney were rather widespread during the susceptible period, but the aggregate losses were as a rule appreciably below the average. This seasonal variation in incidence is a well-recorded factor. In as many cases as possible , the diagnosis in regard to the death of the lamb has been verified, but admittedly in the field a fractional margin of error has to be allowed in this respect, as it is obviously impossible to verify the cause of death in every instance. It appears that the dose of the vaccine prepared by the Commonwealth Serum Laboratories could be increased with advantage at each vaccination. Colostrum and blood samples have been taken from vaccinated and. control ewes. Blood samples have been taken from lambs of each groupat varying intervals. These were forwarded to Wallaceville Laboratory for immunization tests. The results of this work will be published at a. later date. Acknowledgments. The vaccine used in the departmental experiments was prepared at the Veterinary Laboratory, Wallaceville, under Dr. Hopkirk. The vaccination work was largely done by A. L. Thompson, M.R.C.V.5.,. H. Doyle, M.R.C.V.S., and J. Danskin, M.R.C.V.S. Field arrangements were made and observations kept by Messrs.. J. Fleming, A. Douglas, and H. Rountree, Inspectors of Stock at Ranfurly, Lumsden, and Otautau. Thanks are again due to those farmers in Otago and Southland whowillingly co-operated with us. . References. Dayus, C. V. ; Vaccination of Ewes against Pulpy Kidney (InfectiousEnterotoxaemia) in Lambs.” N.Z. Jown. of A gric., Vol. 52, No. 5, p. 289. Oxer, D. T. : “ The Transmission of Antitoxic Immunity from the Ewe vaccinated against Enterotoxaemia to the Lamb.” Australian Veterinary Journal, April, 1936, page 54. ' . . - . : • ; . Wardle, R. N. : “Vaccination of Sheep.” Journal of Agriculture, Victoria,. October, 1936, page 537.

' District and Farm. - Ewes vaccinated. Ewes (Control). Date of First Vaccination. Date of Second Vaccination. Ranfurly - - -■ ’ A 326 325 27/8/36 19/9/36 b .. 175 175 27/8/36 ' 17/9/36 C 150 150 24/8/36 15/9/36 D .. .. IOI IOO 28/8/36 17/9/36 . E 274 226 25/8/36 16/9/36 F 620 650 26/8/36 18/9/36 18/9/36 G 217 217 25/8/36 16/9/36 Middlemarch H 158 105 3/8/36 21/8/36 I 156 .122 3/8/36 • • 21/8/36 Otautau — J 215 215 30/7/36 22/8/36 Mossburn — K 107 IO6 4/8/36 15/9/36 ' L 109 109 4/8/36 15/9/36 Totals 2,608 2,500

Table I. —Vaccine prepared at the Veterinary Laboratory, Wallaceville. (First dose, 5 cc. ; second dose, 10 c.c.)

Farm. Vaccinated Group. Lamb Deaths from Pulpy Kidney. Control Group. Lamb Deaths from . Pulpy Kidney. Remarks. A . . 326 2 325 9 Total losses from pulpy kidney on farm 11 out of 1,150 ewes. B .. 175 ' I ’ .' 175 7 Total losses from pulpy kidney on farm 17 out of 650 ewes. C .. 150 O 150 1 Total losses from pulpy kidney on farm 22 out of 1,030 ewes. D .. IOI 2 .. IOO 2 Total losses from pulpy kidney on farm 18 out of 740 ewes. E .. 274 O 226 O Total losses from pulpy kidney on farm 13 out of 690 ewes.

Farm. Vaccinated Group. Lamb Deaths from Pulpy Kidney. . Lamb • Deaths Control from Group. Lamb Deaths from Pulpy Kidney. Control Remarks. Group. . Remarks. F .. 620 2 650 29 Total losses from pulpy kidney on farm 36 out of 1,500 ewes. One wether lamb in vaccinated , group included, dead day after marking, doubtful if pulpy kidney. G .. 217 O 217 4 ' included, dead day after marking, doubtful if pulpy kidney. Total losses from pulpy kidney on farm 20 out of 1,260 ewes. H . . 158 O 105 17 Losses in previous years stated to be in the vicinity of 10 per cent. Lambing percentage this year 127 per cent., and total loss on farm from pulpy kidney 45 to 50 lambs. I . . 156 I ? , 122 8 Total losses from pulpy kidney this year 18. Last year, lost 75 lambs, was worst season experienced. Owner says up to this season average 10-per-cent. loss. J •• 215 0 215 0 Position unusual, losses generally exceed 5 per cent. One lamb was - lost from control group, but doubtful if pulpy kidney. K . . 107 0 IO6 3 doubtful if pulpy kidney. Death-rate from pulpy kidney in past years, 4 per cent, to 10 per cent. L .. / 109 0 109 4 Seven lambs actually died here, but owing to the ewes leaving the dead lambs it was only possible to identify four lambs which were definitely from control ewes. Usual death-rate is from 2 per cent, to 3 per cent. Totals ,608 . 8 2,500 84

Table II. —The Losses from Pulpy Kidney up to 30th November, 1936, by which Date Mortality had ceased generally, are shown.

Farm. Ewes vaccinated.' Ewes (Control). Date of First Vaccination. Date of Second Vaccination. M 377 1,473 17/8/36 2/9/36 N 182 182 ■ 18/8/36 IO/9/36 O .. .. 186 . 186 18/8/36 . f Group 1 10/9/36 P 396 434 . J 15/8/36 . j Group 2 12/9/36 I28/8/36 12/9/36 23/9/36 Totals .. ' ,141 2,275

Table III. —Vaccine obtained by the Farmers from the Commonwealth Serum Laboratories, Melbourne. (First dose, 3 c.c. ; second dose, 7 c.c.)

Farm. Vaccinated Group. Lamb Deaths from Pulpy Kidney. Control Group. Lamb Deaths from Pulpy - Kidney. Remarks. M .... 377 .. .5 1,473 69 Owing to being unable to procurethe vaccine in time the ewes werevaccinated closer to lambing than desirable. N .. 182 .2. ; I I 182 . 182. " r 4 4 Previous losses on farm about 5 per Previous losses on farm about 5 per . cent. . O .... 186 .3. 186 4 ' Previous losses on farm about 5 per cent. P . . 396 13 434 7 The vaccinated ewes were four and five years old, whereas the majority of the controls were two-tooths. Totals I , 141 22 2,275 . . 84

Table IV. —The Losses from Pulpy Kidney up to 30th November, 1936, in Lambs from Ewes in Table III. ..