METASTRONGYLIN^ 259 



dullness in circumscribed areas, but as a rule it shows nothing abnormal. 

 Usually sjonptoms are only observed upon the appearance of cachexia 

 and weakness following the development of purulent areas in the lung 

 tissue, this finally bringing about the death of the animal. 



Course and Prognosis. — The duration of broncho-pulmonary stron- 

 gylosis varies according to the number of parasites present and the 

 toleration of the affected animal. In the majority of unfavorable cases 

 the disease will run a course of two, three, or four months. In the very 

 young this period may be much shortened, the animal succumbing in a 

 few days from the first observation of symptoms. Strong adult animals, 

 on the other hand, are likely, unless there is reinfection, to gradually 

 recover during a course of six to eight months. In any case where the 

 symptoms are well marked a fatal termination is to be looked for. 



For Post-mortem Appearance, Development and Etiology, Control, 

 and Treatment, refer to pp. 262-265. 



Beonchial and Pulmonary Strongylosis of Cattle 



Dictyocaulus viviparous (Strongylus micrurus). Fig. 132. Meta- 

 strongylinse (p. 256). — The body is long, slender, and attenuated at both 

 extremities. The head is rounded and without wings; 

 mouth circular and nude. The bursa of the male is 

 small, without lobes, and is supported by five ribs. 

 There are two short and strong spicules. The tail of 

 the female terminates in a sharp point; vulva near the 

 posterior sixth of the body. 



Length of female, 6-8 cm. (2 3/8-3 1/8 inches); 

 male, 3.5^ cm. (1 3/8-1 5/8 inches). 



The eggs are oval, 85 microns in length by 35 mi- 

 crons in breadth. Embryos are developed within the 

 body of the female and are liberated at the time the 

 eggs are deposited. 



The liberated embryos are 256 microns long by 25 

 microns in thickness. They pass from the bronchi 

 to the trachea from which they are expelled to the 

 exterior. 



Symptoms. — In light infestations no symptoms 

 may be observed save an occasional cough. When _ 



the parasites are more numerous the cough becomes tyooauius Vivipar- 

 more frequent and sonorous, and, in the further course, ous; male at right, 

 paroxysmal, the animal extending the head, protruding „ ™fs? e^* ^^^*' °^*' 

 the tongue, and freely salivating during the attacks. 

 The paroxysms are accompanied by dyspnoea and suffocation, with 

 beating flanks, quickened pulse, and injected conjunctiva. In severe 



