8 
BULLETIN 3 8, PUERTO RICO EXPERIMENT STATION 
livers and other parts must be discarded. Usually pigs confined in 
dark, damp, and dirty pens harbor heavy infestations with this 
worm. As massive infestations are often found in hogs of the im- 
proved breeds, it is believed by some that they are more susceptible 
than the native pig. It is probable that as these hogs are more apt 
to be closely confined, they are more likely to be exposed to a con- 
centration of infection than the native pig, which may have a free 
range all or part of the time. However, pigs on a free range do not 
escape infestation. 
Symptoms and lesions. — Loss of appetite, swollen abdomen, and 
emaciation are the usual symptoms. Severe infestations may cause 
weakness and paralysis of the hindquarters. The liver is injured by 
the young worms actively migrating through this organ. Most of 
the livers of slaughtered pigs show varying degrees of fresh injuries 
or scar tissue formation resulting from infestations with these worms. 
The mechanical injuries are complicated by bacterial infections and 
pus production. 
Treat me nf . — Un known. 
Prevention. — The eggs and larvae of this worm are readily de- 
stroyed by sunlight, heat, and drying and they cannot survive in 
the open unless they fall in grass, leaves of trees, corn husks, and 
other vegetation. 
The kidney-worm-control plan 2 as developed by the Bureau of 
Animal Industry, United States Department of Agriculture, is ef- 
fective in controlling this parasite, where pastures are used. Most 
of the infective material is passed in the area around the sleeping 
quarters and close to the fences. This plan requires cutting and 
cleaning away the grass and weeds in a strip 3 to 5 feet wide along 
the fences on the sides of the pasture lot and a strip about 30 feet 
wide at the end where the shelters and all other equipment are 
placed. These strips must be kept free of trash and litter while the 
pasture is in use. Providing separate feeding pens for the sows 
and, some distance away, creeps with self-feeders for the pigs also 
helps to control other parasites as well as kidney worms. The pigs 
are kept in this pen with the sows until weaning and then are 
placed on temporary pastures, with only pigs of a similar age raised 
under the same system. 
If the above plan is not followed, pigs should be farrowed in a 
dry, bare yard and then placed on fresh ground after weaning. 
In a general way, the more dense the shade, the more growing vege- 
tation, the poorer the drainage, and the more animals on the same 
area the greater is the need for cleaning up manure accumulations, 
the rotation of yards, and the adoption of a sanitation system. 
HOOKWORM 
The common hookworm, Glohocephatus urosublatvs (fig. 2, E), is 
a slender white worm about 4.5 to 7.5 mm (approximately three- 
sixteenths to five-sixteenths inch) long. These worms are found in 
the small intestine. 
Life history. — Similar to other hookworms; infection probably 
takes place by way of the mouth and of the skin. 
s SCHWARTZ B CONTROLLING KID N E V WORMS IN NWINIO IX SOUTHERN STATES. 
U. S. Dept. Ayr. Leaflet 1 OS, (» pp., illus. I<).",4. 
