Text book of veterinary medicine, Volume 4 (of 5)

by James Law

Among the most important measures are a laxative food, like flax seed gruel, a careful picking of all ticks from the surface, the washing of the skin with a 5 per cent solution of creolin, and the removal of the animals to a tick-free pasture, lot, or building. This at once arrests the introduction into the blood of fresh and continuous accessions of the pyroplasma and, if begun early enough, will determine a mild and non-fatal case.

Prevention. The prevention of the protozoan cattle fever is based on the life history of the parasite, and may be directed (1st) to the destruction of the Boöphilus Bovis; or (2nd) to encreasing the resisting power of the exposed animal, to the Piroplasma Bigeminum. 1st. Destruction of the Ticks. (a) On the cattle. The picking of ticks from the skin is effective if the object is to make the animal safe for a few days only as the boöphilus habitually clings to the skin of the one ox from the stage of seed tick to that of ovigerous female, ready to drop off and lay its eggs. An animal going direct to slaughter may therefore be sent through an uninfested district, even in the hot season with a fair amount of safety, after the careful gleaning of the ticks. The greatest care, however, must be taken to manipulate thoroughly all parts of the skin and above all, the ventral aspect, the inner sides of the limbs, the scrotum, udder and perineum. The animals must be shipped at once after such gleaning of ticks with no further opportunity of taking on a new supply, the cars and other conveyances must be cleaned and treated with acaricides and the litter burned as soon as they are vacated, and the cattle must be passed over no loading banks, chutes nor yards that may by any possibility be used for other cattle unless these are going into slaughter house.

The picking will safely remove all the larger larvæ, and the mature ticks which are ready to lay their eggs, but it cannot be implicitly trusted to remove also the all but invisible embryos or seed ticks, and if the host is preserved these grow up and mature, while if they are accidentally dropped or brushed from the surface, they climb upon the first available ox and mature on that. By passing from ox to ox they may be kept alive for a time in the pens adjoining the slaughter house, but fortunately they do not travel over a few feet and if no cattle escape from such pens there is small risk of their preservation.

Dipping or smearing to destroy the seed ticks on the skin becomes an essential adjunct to, or substitute for, picking. The Bureau of Animal Industry has experimented largely on dips with most important and valuable results, even if they have proved only in a measure successful and desirable. Aqueous dips they early discarded. Poisonous agents like corrosive sublimate and arsenic are liable to poison through absorption and licking, with the added drawback that neither these nor calcium sulphide are at all effective in destroying the ticks. Proprietary sheep dips were abandoned on similar grounds. Baths of cotton seed oil were introduced by Francis, but proved not quite effective even when phenic acid, benzine, gasoline, or different mineral oils were added. Paraffin oil gave the best results, and later a staple sold as extra dynamo oil, which in combination with sulphur (1:100) proved most destructive to the ticks, was adopted. But in the hot season, when such dipping is required, any one of these baths produced heating, and illness in the cattle, and together with the exertion and excitement served to rouse into dangerous activity the germs already present in the blood. Ophthalmia, too, was a very frequent result. If the cattle could be kept on their native pastures the dipping might be permissible, but this was to lose the object aimed at—the wholesomeness of these cattle on uninfected ranges. When shipped north in the hot weather the losses were so great as to be prohibitory.

If, however, it could be reserved for use on the southern pastures, to prevent the maturing of the ticks and the laying of eggs for a future generation, it might be employed to rid the infested pastures of the boöphilus, and consequently of infection. The question, then, is reduced to the comparative advantage of the destruction of the ticks, on the one hand, and the cost of frequent dipping throughout the warm season, on the other. The following season there ought to be no ticks left.

Cooper Curtice advocates kerosene 1 gallon in combination with an equal amount of lard, 1 lb. sulphur, and 2 lbs. pine tar. Melt the lard, add the sulphur and tar, bring to the boiling point, cool, add the kerosene with stirring. Rub daily with a brush on the whole skin but especially inside the arms and thighs. On tick-infested pastures it must be continued through the season, and if thoroughly done will leave the fields tick-free the following year. Like oil dipping it would manifestly be incompatible with immediate shipment on a long railway journey, but Curtice vouches for its efficacy as a means of eliminating ticks from southern pastures. The main question is the expense. What would be perfectly adapted to small herds of very domesticated cattle in North Carolina would be a herculean and expensive task in the large herds of Texas. Curtice mentions cotton seed oil, fish oil and even a small proportion of linseed oil as good substitutes for the lard.

Destruction of Ticks on Pastures. Fields, farms and larger areas can be freed from the boöphilus by the thorough application to the cattle pastured on them of one of the above-described methods, provided that no strange cattle are admitted on the land. The ticks are sluggish and, unless carried on the bodies of animals, do not crawl many feet from where they drop. If cattle are kept in the next lot, they should not be allowed to come in contact with the treated or protected stock, but a double fence with an interval of five or six feet, will prove a sufficient barrier to the advances of the tick, apart from its bovine host.

Cultivation of a tick-infested soil for one year or more, with complete exclusion of cattle from November or December until March or April of the second year thereafter, will exterminate the ticks. During the intervening summer there may be plenty of young live ticks on this land, but, in the absence of the bovine host, and blood, these cannot reach maturity, lay their eggs and thus leave new generations. In the course of the second winter therefore they are exterminated. In restocking such land, it is all important to see that the cattle placed upon it do not introduce any ticks on their bodies. Equally essential is it, to see that cattle are excluded from the cultivated land in winter as well as in summer. During warm days ovigerous female ticks, dropped from the skins of such cattle, may produce eggs and larvæ to start a new crop in the coming summer. But as has happened to the wood ticks of the North, so in the South, cultivation of the soil and the exclusion of cattle for a length of time, will exterminate the race of ixodes.

Exclusion of cattle for two winters and the intervening summer will eradicate the ticks even in the absence of cultivated crops. To reach full maturity and propagate its kind, the tick must have bovine blood. If therefore the ticks of a whole season (spring, summer and autumn) are denied bovine victims, and thus cut short in their development, no crop is left for the succeeding spring. If then a cattle pasture is divided in two parts by a double fence with an intervening space of 5 or 6 feet, and if the cattle are confined to one of these parts for a whole year and are transferred to the second half in January after dipping or smearing with ixodicide oil they may be kept entirely free from ticks thereafter. That half of the pasture which is abandoned in the second year, will be tick-free and salubrious in the third year.

Another resort, advised by Curtice when a large tick-free pasture is available, is to place the infected cattle in a pen, and soil them for three weeks, no longer. Then transfer them to another clean pen and soil them there for three weeks more. Then examine closely, and if entirely free from ticks they can be put in the large clean pasture. Should they still carry a few ticks they should be placed in a third clean pen for two weeks more, when they will be tick-free and may be turned into the large pasture without the formality of examination. This is substantially based on the period of parasitism of the tick on the skin of the ox, and its development from the newly hatched larva (seed tick), to the ovigerous female. This period is from three to four weeks. The greater number of the ticks are therefore dropped off as mature ticks to lay their eggs in the first pen, while the remainder are similarly left in the second pen. As the stock leaves the two pens in succession long before the deposited eggs have had time to hatch out, they can take on no more ticks and emerge from the second pen clear and safe. The same pens cannot be used repeatedly, as the eggs develop into seed ticks in 15 days in hot weather, and at once attack cattle.