410 Journal of Agriculture, Victoria. [10 July, 1918. 



DISEASES OF SHEEP.* 



By W. A. N. Robertson, B.V.Sc, Chief Veterinary Officer. 



The subject that I have been asked to address the farmers in con- 

 vention upon — Diseases of Sheep — is of very great importance, yet I 

 fear, vpith the limited time at my disposal, it is one which can be no 

 more than touched upon, and only a few of the complaints common 

 to sheep can be dealt with. Recognising this difficulty, and still further 

 recognising the confusion that would arise in the minds of most sheep- 

 owners if I were to attempt to describe too many diseases in a short 

 or scrappy manner, it is my intention to deal mainly with some of 

 the causes of disease in general; for, if these are known, more than 

 half the battle is won. It is an old axiom in medicine that if you 

 remove the cause the effect will cease, the effect being that series of 

 symptoms of ill-health which we term disease. This aspect requires to 

 be deeply engraven in the minds of all interested, not only in sheep, 

 but in all live stock. Therefore, we should endeavour, firstly, at pre- 

 venting a cause from operating; and, secondly, if some cause does 

 operate, we should try to remove it. 



In no class of live stock should preventive measures against disease 

 be taken more than in the case of sheep, for it is an animal which 

 does not show many very characteristic symptoms when ill, and which 

 does not respond readily to medicinal treatment. 



The animal body must always be considered as a very delicate 

 and complicated machine, and one which is easily thrown out of 

 efficient running. Most farmers take some care of their engines on 

 (he farm by providing proper fuel, lubricant, and shelter; yet it is 

 far easier to repair or replace a worn-out part of such a mechanical 

 contrivance than it is to effect recovery in the living tissue. The 

 animal frame is composed of a very large variety of substances, which 

 require to be present in certain definite proportions for the efficient 

 working of the whole. These substances can, under natural conditions, 

 be obtained only from the food. When present, all the tissues are 

 first — in the growing animal — built up in a healthy manner, and 

 then maintained in this condition; but it is not only necessary that 

 these substaces should be given to the animal; they must be present 

 in such a form as to be readily assimilated or taken into the system. 

 There are juices or fluids present in the system, which have the power 

 of digesting or making the component parts of a food suitable for 

 absorption. If these juices are not present in sufficient quantity or 

 quality, or if there is any derangement of their proportion, then the 

 full benefits cannot be derived. This is indicated by indigestion, 

 failing health, poverty, &c., and a general lowering of vitality, which 

 open the way for harmful products, whether they be derived from 

 external or internal sources, to exert an influence and produce serious 

 effects. 



Under normal conditions and as a result of digestion of food in the 

 animal body some very powerful poisons are formed. The body, how- 

 ever, is prepared for such happenings, and when they occur, the poisons 



♦ Paper read at the Annual Conference of the Chamber of Agriculture, Colac, July, 1918. 



