SURGERY AND OBSTETRICS 



351 



ParasHes 



Infestation of the castration Avounds with screw-worms (larvae 

 of the Campsomyia macellaria) are very common in the southern 

 part of the United States. These larvas burrow into the tissues, 

 thus mechanically injuring them and providing an avenue of en 

 trance for various bacteria. 



Lesions. — The principal lesion consists of an active, acute in- 

 flammation with or without the production of pus. The surrounding 

 tissues are tumefied, hyperemic, hemorrhagic, and contain the larvte. 

 The extensive tumefaction developing within one or two days after 

 castration is the most evident symptom. On a close inspection, larvte 



Fig. 106. ACTINOMYCOSIS. 



may be observed near or upon the surface, and by manipulation 

 of the lesion larviB may be forced out upon the surface. In cases 

 of screw-worm infestation there is a constant sero-sanguineous dis- 

 charge that by attracting the female fly favors repeated reinfestation. 

 Treatment.— All that can be done in cases of screw-worm in- 

 festation is to support the strength and minister to the comfort 

 of the animal and prevent a further infestation from the deposition 

 of more eggs or larvEe upon the wound and patiently wait for the 

 investing larvffi to reach the stage of development when they volun- 



