18 Williams, Fisher, and Udall: The Spavin Group. 
arthritis deformans the cartilage is the primary seat of the prin- 
cipal changes. In view of these facts Professor Fréhner defines 
spavin as follows: “Spavin is principally an ostitis of the os 
magnum-and medium as well as the metatarsus, from which there 
afterwards secondarily develops a deforming inflammation of the 
tarsal joint. It is more correct, therefore, to define spavin as an 
osteo-arthritis chronica deformans.”  (‘ Allgemeine Chirurgie,” 
1905.) The same term is applied by this author to the changes 
which, occur in ringbone, gonitis, omarthritis, etc. It is obvious 
that the lesions found in the preceding five cases are in accord- 
ance with Professor Frohner’s interpretation of the disease. It 
is further noted that, similar to arthritis chronica deformans in 
man: “it may have a spontaneous or traumatic origin.” Further 
investigations may reveal that the influence of traumata, as direct 
causes of the disease, has been somewhat over-rated. In cases. 
III and IV the existence of a spontaneous (pathological), in- 
direct etiological factor seems to be fairly well demonstrated, 
being present in both a young and an old animal; many careful 
and widely distributed examinations are necessary to determine 
the extent of this influence. 
The causes of “ osteo-arthritis chronica deformans,”’ when 
of “pathological” origin, lack complete and unobjectionable 
demonstration. Rachitis and rheumatism are doubtless operative 
in many cases of the disease when occurring: in young animals; 
the latter may be a more important factor than is generally al- 
leged (“‘ Monatshefte fiir praktische Thierheilkunde,” Vol. XV, 
page 211: “ Rachitische Schale und rachitischer Stelzfuss beim 
Pferde:” Frohner). 
This pathological condition is not confined to young animals. 
The visible lesions may be confined to one or two bones and 
articulations, or be well distributed through those of the extremi- 
ties. 
Clinical examination may lead to diagnosis of lameness in the 
anterior limbs when a post-mortem examination of the same 
animal shows that the disease is more pronounced in the posterior 
limbs (Case IIT). 
URINALYSIS. 
The composition of the urine during this affection has not 
been fully investigated, nor have definite observations been made 
