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INSTITUTE OF INSPECTORS OF STOCK OF N.S.W. YEAR BOOK.
PROTEIN NUTRITION AND CARBON TETRACHLORIDE POISONING IN SHEEP
D.J. Walker, Stock Inspector, Cooma.
The following brief notes amplify our present, and admittedly very incomplete, knowledge of the causes of mortality which may follow the use of a very common drug; and illustrate to some extent the relationship of the plane of nutrition to cases of tetrachloride poisoning.
It has been suggested by Mr. J. F. Litchfield, Hazeldean, Cooma, that in his experience of carbon tetrachloride poisoning the following system of management is particularly likely to lead to losses.
Sheep are removed from a low plane of protein nutrition upon which they have been living for a considerable period to a high plane of protein nutrition for a period of a few days, and then drenched. This grazier is able to give a number of instances in which this type of management has preceded losses, and suggests that the sheep are sensitised to carbon tetrachloride during this "high plane" period, though after they have been on this plane for some time the sensitisation disappears.
The revelant details of three consecutive cases of mortality which have occurred in this district since the suggestion was made are as follows:—
Case 1.—A mob of 1,400 three-year-old wethers was shorn mid-November and dipped mid-December, during which period they were running on hard, granite grass country. On the 19th December the mob was placed on a lucerne paddock. The lucerne was past flowering and its growth fairly scanty, but there still was a good grass growth in the paddock at the time of drenching. The mob was drenched on the 29th December with 5 ml. double strength carbon tetrachloride. Total mortality was about 460 head.
Case 2.—On the 26th April, 1,230 three and four-year-old wethers in poor condition were moved a distance of 12 miles from poor granite country to red to chocolate basalt country, arriving on the 27th April. The movement involved the sheep being placed for 24-48 hours on an considerably improved plane of nutrition. They were drenched on the 28th and 29th April. Total losses were 100 head.
Case 3.—On the 6th February, 400 mixed sheep were drenched with 5 ml. single strength carbon tetrachloride. Deaths commenced a week later and by the 21st February 120 head were dead and 35 seemed unlikely to recover. Between the 10th and 17th of the preceding January 462 points of rain fell, so that the sheep were on an improved plane of nutrition after being on a low plane for a considerable period. At the date of drenching the sheep had picked up and were improving.
In each of the above cases weather conditions and all other known factors contra-indicating the use of this drug had appeared to be favourable.
DISCUSSION.
Reference to an outbreak by A. L. Rose (1932) does not support the suggestion. The history of one outbreak reported was that a mob of 900 and another of 1,500 were mixed. The same day 430 were drenched. The next day 350 and 720 were drenched. Losses occurred only in the 350 head; 131 being affected, 80 of these dying. It appears that this mortality at least could not be explained through the plane of nutrition before drenching.
When the precaution recommendations by Ross and Gordon (1936) are considered it is not at all unreasonable to examine the possibility of two or more physiological conditions predisposing to poisoning. Factors which at different times have been thought to have a bearing on susceptibility to poisoning are pregnancy, the feeding of concentrates, changes of paddocks and hypocalcaemia.
Whilst these observations may not be correct in all particulars they are of definite interest, and if a correlation of losses with any type of management can be shown in sufficiently high percentage of outbreaks, the way will be open to making further recommendations for avoiding losses. In addition, further detail will be available in case histories which in the past probably have not supplied sufficiently detailed information concerning nutritional variations during the month prior to drenching.
References:
Clunies Ross, I, and Gordon. H. McL. (1936).—"The Internal Parasites and Parasitic Diseases of Sheep." Angus and Robertson: Sydney.
Rose, A. L. (1932). — Aust. Vet. J., 13: pp. 122-137.