Parasites and Parasitic Diseases of Dogs 23 



swallowed by a suitable host the egirs hatch and the young worms 

 develop for a short time in the small intestine and subsequently in 

 the cecum (the blind gut at the union of the small and large intes- 

 tines). Here they apparently enter the mucosa by means of a 

 piercing lancet in the mouth of the young worm. As the worm 

 develops, the anterior portion of the body remains sewed into the 

 mucosa, while the posterior portion hangs free in the lumen of the 

 cecum. The worms apparently become mature in about three months. 

 In heavy infestations these worms may occur in the colon as well 

 as in the cecum. 



Symptoms. — These worms not infrequently give rise to a low- 

 grade inflammation at the point where they attach, and as they are 

 most commonly present at the tip of the cecum this is the place 

 where a reddened area is most often seen. The worm's habit of 

 sewing into the mucosa opens small w^ounds which probably afford 

 entrance for injurious bacteria. A closely related species of worm 

 in man appears to be responsible for symptoms of distress resembling 

 a low-grade appendicitis. The exact symptoms produced by these 

 worms in dogs are as yet matters which require more careful inves- 

 tigation than they have received. In many cases the worms appear 

 to do little harm and to cause no visible symp- 

 toms. 



Treatment. — ^AYhipworms are not very re- 

 sistant to the drugs which are injurious to para- 

 sitic worms in general, but at the same time the ^^^ .-^.^ _^ a- of d 

 removal of these worms is somewhat difficult. Whipworm: "Enlarged. 

 Apparently the reason is that it is difficult to get Hi? ^'^'^ ^°^ ^^^'^' 

 the drugs in contact with the worms. In their 

 passage through the stomach and small intestines drugs are greatly 

 diluted with the contents of the digestive tract and are also ab- 

 sorbed to a greater or less extent. Of the amount of drug which 

 reaches the ileocolic valve, at the union of the small and large in- 

 testines, only a little and perhaps none will enter the cecum or get 

 to its tip where the worms are usually situated. Consequently a 

 single dose of a drug is less likely to reach and kill the worms than 

 it is to miss them, "^^^len a number of repeated doses are given, 

 the likelihood of the drug's reaching the worm is greatly increased. 

 At present the most satisfactory and feasible treatment consists in 

 the daily administration of equal amounts of santonin and calomel in 

 the morning, in doses of one-fourth to 1 grain each, according to 

 the size of the dog, the treatment being kept up for a week, sus- 

 pended for a week, and then repeated for a week. In place of using 

 this routine treatment over a period involving three weeks, the treat- 

 ment may be kept up as long as the whipworm eggs appear in the 

 feces on microscopic examination, suspended whenever they disap- 

 pear, and stopped if repeated examinations of the feces show that 

 eggs are no longer present. 



TAPEWORM INFESTATION 



Cause. — Tapeworms are elongated, flat worms made up of few 

 to numerous segments and with a head, which is usually provided 

 with four suckers and two or more hook circlets. The head is 

 located at the small end of the worm. Dogs are infested with a 



