356 Annual Report for 1911 of Royal Veterinary College. 



As ever}^ new worm thus added to the stomachs of the sheep 

 increases the number of eggs passed out with the faeces, in the 

 circumstances considered the ground must soon become highly 

 polluted with eggs, and only the accident of unfavourable 

 weather conditions can then prevent a serious outbreak. 



Unfortunately information is still lacking regarding some 

 important details in the life cycle of these parasites. It is 

 known that under the most favourable conditions the eg^s may 

 hatch out in a few hours, but it is not known what, at different 

 seasons of the year, is the shortest period within which the 

 young worms may reach the stage which fits them for residence 

 in the sheep's stomach. If this were known one could fix the 

 time within which sheep must be moved from one field or plot 

 to another. In the circumstances one can only advise that the 

 flock should be given a change of ground as often as possible, 

 and that frequent changes are imperative when a large number 

 of sheep are kept on a small area. The benefit of frequent 

 changes is shown by the fact that outbreaks of parasitic 

 gastritis are uncommon among sheep fed on growing roots and 

 other crops on ploughed land. 



It has already been mentioned that the young worms after 

 they have reached a certain stage of development are very 

 tenacious of life, but it is probable that such worms perish in 

 less than a year if they do not obtain access to the sheep's 

 stomach. Ploughing and ci'opping are absolutely reliable for 

 destroying the worms, no matter how badly polluted the 

 pasture may be, but it is doubtful whether such dressings as 

 lime and salt are of any value in this direction. As a rule 

 pasture can be kept safe for sheep by alternately grazing it 

 with sheep and cattle, because the two species of worms which 

 are most frequently the cause of parasitic gastritis in sheep 

 seldom or never cause disease in cattle. 



When an outbreak has already begun it may generally be 

 assumed that every member of the flock is in danger because 

 of the large number of worms already in the stomach, and it is 

 therefore of the utmost importance to detect the earliest cases, 

 and to take steps to check the further infection of the flock. 

 Loss of condition and diarrhoea are the usual symptoms, and at 

 an advanced stage of the disease the head may appear swollen 

 owing to the presence of dropsical liquid beneath the lower jaw. 

 Animals presenting these symptoms should be removed from 

 the flock, and if possible kept indoors and fed liberally out of 

 troughs, as that diminishes the chance of infection with faeces. 

 The place should be frequently cleaned out, and the manure 

 burned or ploughed down. For the reasons already explained, 

 the remainder of the flock should be frequently moved, and 

 if they are at grass all overcrowding must be avoided. 



