56 GUIDE TO THE STUDY 



the maintainence of some of the most important parasites of man 

 and domestic animals. 



We have seen the extent and variety of parasitic infection of 

 the common frog. Of the mammals, the domestic cat serves as 

 a convenient subject for similar examination. Over a hundred 

 species of parasities have been listed for this animal, though 

 of course in a given locality an individual animal might harbor 

 very few representatives. The present practicum will illustrate 

 a simple routine for the examination of any small mammal. 



PRACTICAL WORK 



Preliminary Examination. — Search the fur carefully for 

 ectoparasites such as ticks, lice, and fleas. Place any of these 

 in the bottles of 70 per cent alcohol provided, and record their 

 presence. It should be recalled that lice and fleas serve as 

 intermediate hosts of the double-pored tapeworm of cats, and 

 hence if your animal harbors this worm a percentage of the insects 

 would probably be infected. 



Examine for evidence of mange, such as falling hair and 

 wrinkled, crusty skin particularly about the ears and upper 

 part of the neck. If these conditions are encountered, make 

 scrapings of the crusts and search with the microscope for the 

 causative mite, Notoedres cati. Examine scrapings from the 

 auditory canal for the ear mite, Otodectes cynotis. Mounting 

 the scrapings in 5 per cent caustic potash will render the parasites 

 more distinct. 



Preparation for Dissection. — Stretch the animal on its back 

 on a broad dissecting board or tray and tie its extended legs. 

 Wet the fur of the abdomen and part it along the midline. 

 Then insert a scalpel just under the skin in the midline of the 

 throat and slit the skin to the anus. Loosen the skin and pin 

 it down on either side. Being careful to avoid piercing the intes- 

 tines, make a longitudinal cut through the abdominal muscles 

 from the sternum to the pubis and a lateral cut along the last 

 ribs, and pin out these flaps with the skin. With bone cutters 

 {not with scissors) cut through the ribs of both sides and, com- 

 pleting the cuts with a scalpel, lift off the sternum and attached 

 stumps of ribs. 



Before proceeding further, examine the abdominal and 

 pleural cavities for larval tapeworms or other parasites. An 

 elongated plerocercoid 2 to 3 cm. long by 2 to 3 mm. broad has 



