PARASITES AND PARASITIC DISEASES OF HORSES ai 
combs and brushes should be treated each time a horse is groomed. 
Harness, saddles, blankets, and other equipment used on lousy ani- 
mals should not be put on horses that are free from lice unless the 
equipment has been thoroughly cleansed. 
When cleaning stables and yards remove all litter’and manure 
down to a smooth surface, then spray well with a good insecticide. 
The coal-tar cresote dips, diluted in accordance with the instruc- 
tions printed on the label of the container, are suitable for ridding 
premises of the lice. 
Treatment.—None of the dips recommended for use in treating 
horses can be depended on to eradicate lice at one dipping. The first 
dipping, 1f properly done, will probably kill all the lice, but it may 
not destroy all the eggs. The nits or eggs which survive dipping 
often hatch, forming a new generation of lice. This new generation 
should be destroyed by a second dipping after hatching is completed 
and before the young lice become mature and begin depositing eggs. 
Since these two periods overlap somewhat and vary greatly, and be- 
cause the periods from hatching to egg laying are different for the 
sucking and biting lice, it is impossible on this basis to calculate the 
exact period that should elapse between dippings. Young lice ap- 
pear on dipped animals as early as the third day after the first dip- 
ping, and since the average period of maturation is about 12 days it 
seems evident that the second dipping should be given in about two 
weeks. Experience has shown that two dippings with an interval 
of from 14 to 16 days usually can be depended on to control both 
sucking and biting lice. 
The dips commonly used for destroying lice on horses, mules, and 
asses, named in the order of their effectiveness, are arsenical solution, 
coal-tar creosote, and nicotine. The arsenical solution is poisonous, 
and unless handled with due precaution injury to man and animal 
may result. When properly used, however, it is the most depend- 
able known dip for destroying lice. The coal-tar creosote dip is ef- 
fective when used in reasonably good water. Two dippings, from 14 
to 16 days apart, in either of these dips can usually be depended on to 
eliminate horse lice. Two dippings in nicotine solution will ordi- 
narily free horses from lice. On account of the difficulties in dipping 
in cold weather, and the unsatisfactory nature of hand treatments, 
most of them only palliative, it is advisable to dip for lice, when they 
are present, in the fall of the year before the onset of cold weather. 
Hand applications of dusting powders and oils and greases are 
often resorted to in treating horses for lice. Some of the dusting 
powders are of value in holding the parasites in check, but, as a rule, 
they are not effective in controlling sucking lice. Biting lice can be 
destroyed with sodium fluoride applied in the form of a powder or 
mixed with water in the proportion of about 1 ounce to 1 gallon; but 
sodium fluoride is not effective against sucking lice. Care should be 
taken not to apply sodium fluoride too freely around the natural 
body openings or where the skin is very thin and hairless, and not to 
rub it into the skin. It may be applied with a dust gun, or a shaker, 
or by hand. 
Oils and greases, such as crude petroleum, crank-case oils, or equal 
parts of cottonseed oil and kerosene, are effective remedies for lice; 
but ordinarily they are not suitable for use on horses, as they cause 
the hair to come out, and they often blister the skin. 
