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granuloma that is commonly found affecting horses in the 

 Solomon Islands. 



The following information has also been kindly sup- 

 plied . — About 75 per cent, of horses in the Solomon Islands 

 suffer from a form of "swamp cancer," which attacks the 

 pasterns only. The tumours vary in shape and size from those 

 showing a flat, raised surface with a diameter of about 1 inch 

 to those showing a rounded surface and a size somewhat larger 

 than a cricket ball. The lesions do not appear to cause the 

 animals any pain. They are very chronic and may last for 

 years. They do not appear to occur at one time of the year 

 more than another. The animals, for the most part, are grass 

 fed, worked through the day and turned out in the horse- 

 paddock at night. Horses running at pasture appear to be 

 affected in about the same proportion as those at work. The 

 horses are mostly used for saddle work. The district is com- 

 paratively dry, but is subject to very heavy dews. The area 

 is threaded with tidal lagoons, usually closed at the mouth. 

 Horses having no access to swamps or waterholes are commonly 

 affected. The animals are never more distant than a mile 

 from habitations. 



The macroscopic appearance of the tumours is very similar 

 to that of habronemic granulomata. The surface is usually 

 ulcerated. The tumour is very dense and tough, and on section 

 is seen to contain numerous yellowish, caseo-calcareous nodules, 

 not usually larger than a millet seed. These necrotic areas 

 are more numerous than seen in tumours occurring in Aus- 

 tralia. A vertical section of one tumour, with an area of 

 approximately 10 sq. cm., contained approximately 140 

 necrotic areas, some more or less sclerosed. 



The microscopic picture is very similar to that described 

 as found in habronemic granulomata in Australia. The differ- 

 ences are due to the more chronic nature of these tumours. 

 The fibrous tissue is dense and sclerosed. The tissues are 

 infiltrated with eosinophile leucocytes. Many o.' -,*he necrotic 

 areas have been absorbed and their place taken by fibrous 

 tissue. This process is seen in various stages. .There is a 

 marked tendency for the occurrence of a deposit of calcareous 

 material in the necrotic areas. Larvae showing a cuticle with 

 fine longitudinal ridges are seen in various stages of 

 degeneration. 



It is apparent that the larvae present are not all of the 

 same age. Many appear to be well preserved and of recent 

 advent, while others, have completely disappeared, leaving only 

 the worm canals in the necrotic areas. The necrotic areas are 

 also in various stages of absorption. It appears, therefore, that 

 f2 



