66 ON PSORIASIS IN HORSES, ETC., 



common in blackfellows' dogs, might be similarto that in horses^ 

 but I now know that these diseases are distinct. • 



Dog mange I found to be caused by the excessive increase 

 of a parasite in the skin, the Drunxh'.r fdJIindonoii. 



I believe the disease has always been present in horses in 

 the colony, but as attention had not been directed to it, it 

 was generally overlooked. This condition is a skin disease of 

 the scaly or psoriasis type, closely resembling psoriasis in man, 

 and like it difficult of cure, and prone to reappear after 

 apparent cure. It might be classed as a constitutional disease. 



It is neither contagious nor infectious in any sense. 

 Affected horses are apparently perfectly healthy in other respects, 

 but as they sutler a good deal from irritation, this may in very 

 severe cases cause emaciation. The cause appears to be climatic, 

 and the disease occurs almost exclusively in horses that are not 

 stabled or groomed. 



Mangy horses will generally get well when stabled and 

 otherwise cared for, but they get the disease again if turned out 

 at nights. Stabling at nights appears the essential point in the 

 treatment ; arsenic internally and chrysophanic acid ointment 

 by inunction should also be tried. Parasiticide remedies appear 

 to be valueless. 



The cause has been frequently stated to be the Trichoplniton 

 fungus, or one closely allied to it. Now I have never seen a 

 trace of fungus in any of my preparations, and I have made 

 some thousands. 



The experts in microscopy at the Brown Institution, 

 London, to whom specimens were submitted from here by the 

 Chief Inspector of Stock, were unable to detect any parasite. 

 There is frequently to be seen a peculiar arrangement of the 

 pigment in the skin which, with low powers of the microscope, 

 might be mistaken for a fungus, but by careful illumination 

 with the Abbe condenser and witli high powers, it resolves itself 

 into large branched pigmented cells ; it is not confined to mangy 

 skin, but can be seen m healthy skin also, which fact of itself 

 is sufficient to show it to be a normal condition and in no way 

 connected with mange. 



