BOT FLIES AND HORSES

New Zealand Mail, 21 February 1901, Page 51

BOT FLIES AND HORSES

The following letter lias been received by the Agricultural Department addressed to Mr J. A. Gilruth. Government Veterinarian, from Mr D. E. Salmon, Chief of the Bureau of Animal Industry, United States Department of Agriculture: —“Replying to your letter of the 19th November, I desire to say that veterinarians in this country make no attempt- to treat horses for hots, as it is not considered that the)' do the horses any injury. On the contrary, it is asserted by sc me that as a result of the little irritation produced by tlieir holding on to the mucous membrane of the stomach that organ is stimulated and digestion is promoted. In this country, about May and June, they are expelled with the excreta, and stablemen and others who notice them in the manure will sometimes exclaim that ll;e horse has bots. This, of course, is nothing but the evolution of this parasiteThe mature bots, as they are passed from the horse at this period, penetrate a- little beneath the soil, or under various objects until their wings appear, when they are apt to crawl up on a blade of grass or straw, dry off, and fly away to lay more eggs, either on the legs of horses, or they may deposit them in various places such as the margms of pools of water, so that when such water is drunk by horses or the eggs are licked from the forelegs, they hatch out in the stomach to form hots again, which normally remain in the stomach of the horse for about eight months of the year, and can be found in the stomach of any horse in this country that is turned out to pasture during the summer and early fall, when the gad-flies are flying. This being the general impression in this country with regard to hots in the horse, your papers must be in error in representing that a decoction of tansy is recommended by this department- for the purpose of expelhng them from the horse’s stomach. Ta i y has been used ; turpentine has been used, and various anthelmintics; but I am not aware that any of them have any effect upon the bots, and do not believe that the bots are a serious detriment to the horse. Unless in very great numbers, they do not attach themselves at all to the secreting half of the stomach, but show a preference for the oardia, which is lined by a mucous membrane like that of the oesophagus. There is an impression which prevails among farmers, and, to an extent, among horsemen, in this country, that the presence of bot-s in the stomach of the horse is frequently the cause of colic, and sometimes the cause of the rupture of that viscu-s. While they may at times, cause colicky pains through the irritation produced by their little hooks and spikes, especially after they hay© entered the intestines, they certainly do not eat through the gastric wall, or cause perforation of the stomach, and when rupture of the stomach is revea-1-

ed upon post-mortem examination of the animal that has had colic, it has undoubtedly been due to over-distention, most frequently as a result of the accumulation of gas, even though bots are found in considerable numbers in the stomach."