ARCHIVE FILE
This article was published in 1967
See the original document
INSTITUTE OF INSPECTORS OF STOCK OF N.S.W. YEAR BOOK.
Some Effects of Route of Administration and Dilution on the Toxicity of Carbon Tetrachloride Drenches for Sheep
C. D. GEE, B.V.Sc., Veterinary Inspector, Goulburn
Introduction
The common dosage of 5 ml. of 40 per cent carbon tetrachloride (CCl) in liquid paraffin will result in the dose being swallowed into the rumen of most sheep (Gordon, 1949).
The administration of carbon tetrachloride into the rumen suggests a potential danger of inhalation of injurious quantities of carbon tetrachloride vapour, as significant proportions of eructated gases may enter the trachea and lungs (Dougherty and Cook, 1962).
The toxic effects of inhalation of carbon tetrachloride vapour have been well known in the medical field for many years (Sherman and Binder, 1944; Harris, 1952).
One of the aims of this experiment was to compare the toxicity of 40 per cent carbon tetrachloride in liquid paraffin by intra-ruminal and intra-abomasal administration.
The second aim was to compare the toxicity by intra-ruminal injection of a 20 per cent solution of carbon tetrachloride in liquid paraffin with the toxicity of a 40 per cent solution.
Materials and Methods
The experiment was carried out in June, 1966, at Crookwell. New South Wales. Twenty-four mature Merino wethers in good store condition were randomised into three groups of eight sheep. The sheep were kept in yards and fed good quality lucerne chaff ad lib. for 12 days before treatment and until the termination of the observations after treatment. Water was available at all times.
Lactic acid casein was used as described by Kondos and McClymont (1965). All sheep were given three doses of 60 g. of casein by stomach tube at intervals of three hours, the first dose being given simultaneously with the carbon tetrachloride.
The carbon tetrachloride treatments were: Group 1: Treated with 12.5 ml. of a proprietary 40 per cent carbon
tetrachloride drench (Tetra Wyn Fluke Drench-Clifton's Rural Products, Goulburn Street, Crookwell) by injection into the abomasum. Group 2: Treated with 12.5 ml of the same 40 per cent carbon tetrachloride drench injected into the rumen. Group 3: Treated with 25 ml. of a proprietary 20 per cent carbon tetrachloride drench (Clifton's Blue Tetrawyn) by injection into the rumen. The mineral oil base of "Blue Tetrawyn" was a high-grade medicinal liquid paraffin meeting British Pharmacopoeia standards for viscosity and freedom from carbonisable impurities. The base oil of "Tetra Wyn" (Shell S.2979) was a grade of technical white oil with a specification well below British Pharmacopoeia (B.P.) standards for medicinal liquid paraffin. The specifications for the base oil of Tetra Wyn" call for an oil of kinematic viscosity 15.37 centistokes (es) at 100°F. (B.P: 64 cs.) and carbonisable impurities up to 5 per cent (B.P.: only traces allowable)
The sheep were kept under close observation for 48 hours after treatment. Autopsies were conducted on all sheep which died after treatment. At 24 hours the survivors at that time were blood sampled.
Portions of lung, liver and kidney were submitted from each dead sheep to Glenfield for histopathology. Lung sections were taken from the lung opposite the side on which the sheep was lying to avoid hypostatic congestion. Serum samples taken 24 hours after dosing were frozen as soon as possible and examined at Veterinary Research Station, Glenfield, for glutamic oxaloacetic transaminase (G.O.T.) and bilirubin levels. The method used was that of Reitman and Frankel (1957) for G.O.T. determination, and a modification of that of Rappaport and Eichorn (1943) for bilirubin.
The abomasal injection technique was that attributed to H. Whitlock (Departmental files). The sheep were suspended in such a way that the zyphoid process was the lowest hanging point. Long 16-gauge hypodermic needles were used and a small quantity of stomach content was removed. Examination of pH was carried out using Universal indicator. A value no greater than pH 5 was accepted as proof of entry into the abomasum. Observations at Goulburn abattoir had shown this to be a reliable criterion.
Weather conditions were cold, still and dry. There was a heavy frost during the night after treatment.
Results
Four sheep died in group 1. Two were dead at 24 hours and another two at 26 hours. One sick sheep from group 1 was examined at 24 hours. This sheep was in a state of hypertonus and opisthotonus in lateral recumbency. There was frothing from the mouth.
One sheep died in group 2 at about 24 hours. This animal was in extremis at 22 hours. It was in lateral recumbency and showing continuous leg movements.
One sheep died in group 3 at 28 hours. This animal became recumbent at the 22nd hour and died quickly with frothing at the mouth prior to death.
The death rate appeared to be significantly higher in group 1 than in group 2. However, one sheep died in each of groups 2 and 3.
All post-mortem examinations revealed changes usually observed in carbon tetrachloride poisoning. Frothing from the mouth was noted before death or at autopsy in both the dead sheep from groups 2 and 3 and in two of the four from group 1. Haemorrhagic congestion of the duodenum was noted in the autopsies of all four sheep from group 1 but not in the autopsies of the two animals from groups 2 and 3.
There was centrilobular necrosis in all liver sections. Kidney histopathology was masked by autolysis in most cases. However, in the two animals in which there was no kidney autolysis, the kidney changes were not significant in one and there were a few calcareous casts in the medulla of the other. A feature of the histopathology was the observation in all cases of some lung oedema with associated congestion or acute pneumonia.
The effect of the carbon tetrachloride on appetite was not specifically studied. However, it was noticed that all treated sheep did feed freely on the lucerne chaff in the self-feeder during the first four-six hours after carbon tetrachloride treatment.
Results of determination of S.G.O.T. and bilirubin are set out in Table 1 One serum sample from group 1 was haemolysed and was excluded from the calculations.
TABLE 1
Mean serum bilirubin and G.O.T. in survivors at 24 hours
| Group | Sheep sampled | S.G.O.T. Units/ml. mean (range) | Bilirubin ug./ml. mean (range) |
|---|---|---|---|
| 1 | 3 | 1097 (52-1670) | 3.45 (3.1-5.4) |
| 2 | 7 | 1754 (1410-2650) | 2.8 (2.5-4.6) |
| 3 | 7 | 850 (620-1150) | 1.760-5.3) |
Discussion
The first observation to be considered is in relation to the first aim of the trial. Four sheep died in group 1 and only one in group 2. The bilirubin levels were also higher on the average in the group survivors than in the group 2 survivors. On the other hand, the G.O.T. levels were higher for the seven survivors of group 2 than for the three satisfactory serum samples from the four survivors in group 1. However, the group figure was the average of only three animals. Also the four animals, which probably had the greatest degree of liver damage in group 1 had been eliminated by death. Hence the significance of the difference in serum G.O.T. levels between groups 1 and 2 is open to question.
The only difference in the treatment of the sheep in groups 1 and 2 was the route of administration. The greater toxicity by the abomasal route appears to be best explained by postulating a higher rate of absorption in the case of this route.
The hypothesis that carbon tetrachloride toxicity in the ruminant could he complicated by eructation from the rumen and subsequent inhalation into the lungs was not supported by this observation.
In relation to the second aim of the trial the mortality was identical between groups 2 and 3. However, as only one sheep died in each group, the mortality figures were not high enough to allow a conclusion that the toxicity was the same in the two groups. On the other hand, the average G.O.T. and bilirubin levels apply to seven animals in each group. These figures indicate a higher toxicity in group 2 than in group 3.
There were two differences between the treatments of the sheep in groups 2 and 3. First, there was a difference in the concentration of carbon tetrachloride in the mineral oil. Secondly, the base oils differed in purity and viscosity. It is impossible to state whether the lower toxicity of the "Blue Tetrawyn" treatment in this trial was due to the lower concentration of the drug or to the higher grade oil base.
The observed difference in toxicity between groups 2 and 3 suggests the need for further more specific studies of different strengths of carbon tetrachloride in the same base oil and of the drug at a uniform strength in high- and low-grade oils.
The observation that all sheep fed freely in the period of four-six hours after treatment is of some interest. The effect of dietary intake after carbon tetrachloride treatment obviously cannot be ignored on the grounds that the drug depresses appetite.
The well-marked haemorrhagic congestion of the mucous membranes of the duodenum observed in the autopsies of the four animals from group 1 is also of interest. The correlation of this lesion with abomasal administration suggests that this was a local effect due to the carbon tetrachloride solution reaching the duodenum in greater concentration in the group 1 sheep.
Summary
The toxicity of 5 ml. of carbon tetrachloride for sheep by intra-abomasal and intra-ruminal injection was compared. In terms of mortality the intra-abomasal route resulted in the greater toxicity.
The toxicity of 5 ml. of carbon tetrachloride for sheep as a 20 per cent solution in a liquid paraffin of high purity and viscosity was compared with the same volume of the same drug as a 40 per cent solution in a liquid paraffin of lower purity and viscosity. There was no difference in mortality although the mean serum G.O.T. level in the group treated with the 40 per cent solution was more than twice that for the group treated with the 20 per cent solution. Serum bilirubin levels were also more than 50 per cent higher in the group receiving the 40 per cent solution.
Acknowledgement
The encouragement of the Director of Veterinary Research, and the examination of samples by members of the staff of the Veterinary Research Station, Glenfield, are gratefully acknowledged.
This work was supported by the provision of materials and assistance by Mr. J. E. Clifton, Clifton's Rural Products, Crookwell.
References
Dougherty, R. W. and Cook, H. M. (1962) — American Journal of Veterinary Research 23:997
Gordon H, McL (1949) — Inst. Insps. Stock N.S.W. Yr. Bk. 1949:58
Harris, F.H. (1952) — U.S. Armed Forces Med. J. 3:1023
Kondes A. C. and McClymont, G. L. (1965) — Aust. vet. J. 41:349
Reitman, S. and Frankel S. (1957) — Amer. J. Clin. Path. 28:56
Rappaport, F. and Eichorn, F. (1943) — Lancet 1:62
Sherman, S. R. and Binder, C. F. (1944) — U.S. Naval Med. Bull. 43:590