32 



CIRCULAR 338, U. S. DEPT. OF AGRICULTURE 



Treatment. — There is no satisfactory treatment for salmon poison- 

 ing ; all drugs tried for the removal of the flukes have proved to be 

 ineffective. It is reported that the disease may be prevented by the 

 use of apomorphine within a few hours after dogs have eaten para- 

 sitized fish. The best prevention, of course, is to keep dogs from eating 

 raw salmon taken in the area in which salmon poisoning occurs. 



Figure 31.— The tongueworm, Linguatula serrata. Upper figure, entire 

 animal. Lower left-hand figure, head. Lower right-hand figure, 

 female tail, showing uterovagina (dotted) and intestine. Enlarged. 

 From Sambon, 1922. 



TONGUEWORM INFESTATION 



Cause. — The tongueworm, Linguatula serrata (synonym, L> 

 rhinaria), is not a true worm, but is a degenerate relative of the 

 spiders, ticks, etc. It lives as an adult in the nostrils of the dog and 



some other animals, 

 and in this stage it 

 is a worm like 

 animal with exter- 

 nal ringlike segmen- 

 tation (fig. 31). 

 This parasite does 

 not infest cats. The 

 male is about four- 

 fifths inch (18 to 20 

 millimeters) long, 

 and the female is 

 about 3 to 4 inches 

 (8 to 10 centimeters) 

 long. The eggs (fig. 32) from the female worms in the nostrils of the 

 dog pass out in mucus when the dog sneezes or are swallowed and pass 

 out in the feces. When these eggs are swallowed by suitable host 

 animals in eating contaminated vegetation, as by herbivores in grazing, 

 the eggs hatch and the larvae make their way, as a rule, to the liver, 

 lungs, and lymph glands and there develop to the infective stage. In 

 the United States these larval tongueworms are fairly common in 

 cattle in the South; in Europe sheep are the most common intermediate 

 hosts. In view of the fact that the larvae may also 

 occur in man, and that the adult is reported from 

 man in one case, this parasite must be looked on as 

 dangerous. Up to the present time it has been found 

 in the dog only in Georgia, but it undoubtedly has a 

 much wider distribution in this country, as the pres- 

 ence of the larvae in cattle shows, and failure to find 

 it is largely due to failure to look for it. 



Symptoms. — Dogs infested with tongueworms may 

 show no symptoms or may have sudden attacks of 

 sneezing, coming on when the dogs are active for any 

 reason. There is often loud snoring, sometimes with almost complete 

 stoppage of breathing. The animal may rub its nose with its paws as 

 if to remove some obstacle. It is interesting to note that tongue- 

 worms have been found in dogs affected with what have been called 

 "running fits" or "fright disease," a condition not yet very well 

 understood. The same condition has been noted in dogs heavily 

 infested with hookworms, and relief reported after successful treat- 

 ment for hookworms. What relation these parasites or others might 

 have to "running fits" is not known. 



Figure 32.— Egg of 

 tongueworm. En- 

 1 a r g e d . From 

 Koch, 1900. 



