Postmortem studies of over two hundred equines in Panama revealed active verminous arteritis or aneurysm in about 80 per cent of the cases. The disease was encountered in animals of all ages, in both native and imported stock, and in horses, mules, and burros. The typical lesion affected the anterior mesenteric artery and was characterized by tortuosity, sclerosis, thrombosis, and diminished caliber. Usually there were less than ten worms—larvae of Strongylus vulgaris (Looss, 1900)—in the lesions. Many of the animals covered in this survey were condemned because of unserviceableness, although a larger proportion was reasonably representative stock of this locality. The probable effect of verminous arteritis upon the efficiency of equines was emphasized and the prerequisites for the type of control needed in this region were outlined.
The authors wish to acknowledge their indebtedness to the following individuals whose coöperation made this study possible: Mr. J. H. K. Humphrey, Assistant Chief Quartermaster of the Supply Department of the Panama Canal; Lt. Col. C. W. Greenlee, V.C., U. S. A.; Lt. Col. H.S. Eakins, V.C., U. S. A.; and the interior ranch owners of the Republic of Panama.