992 DISEASES OF THE HOCK. 



hopeful. The inflammatory symptoms may gradually subside and 

 the disease assume a chronic course ; or the joint may burst, or 

 suppurate. So long as only synovia escapes from the opening, 

 recovery may follow treatment by continuous irrigation ; but when 

 suppuration occurs, the horse surfers intensely, rests little even when 

 in slings, rapidly loses flesh, and owing mainly to exhaustion, arising 

 from fever, failure to feed, and loss from wound discharge, slaughter 

 becomes imperative. 



V.— CHRONIC INFLAMMATION OF THE HOCK. SPAVIN. 

 ARTHRITIS CHRONICA DEFORMANS TARSI. 



For a long time the nature of this disease remained obscure, and 

 it was sometimes thought to be a bone affection, sometimes an affection 

 of the ligaments. Havemann first directed attention to the disease 

 of the articular surfaces, and Schrader and Schiitz afterwards described 

 the condition thoroughly. At the present day no doubt exists that 

 spavin is due to chronic inflammation of the hock, and the only question 

 is, in what structure does the disease originate ? 



The view that the bone tissue forms the primary seat of spavin 

 disease is old, but has again been advanced by Gotti and others, who 

 suggest that spavin should be regarded as a chronic deforming osteo- 

 arthritis. According to the very careful investigations of Gotti, 

 whose accuracy has been confirmed by Bayer, Frohner, and Eberlein, 

 spavin begins as a slowly developing rarefying ostitis of the cuneiform, 

 scaphoid, and metatarsal bones, and gradually extends to the articular 

 surfaces, or towards the periphery, or in both directions at the same 

 time. In the rarefying process the bones undergo partial decalcifi- 

 cation, with the formation of spaces containing granulation tissue. 

 Condensing ostitis or osteo-sclerosis follows the rarefying ostitis. 

 but for a time the articulations and periosteum may remain intact ; 

 eventually, however, by extension of the disease, lesions appear in 

 the articular cartilages (deforming arthritis, central anchylosis). 

 or at the free borders of the bones (spavin enlargement, peripheral 

 anchylosis), and finally the affected bones become fused into a single 

 mass. Hertwig, and the Gunthers are among the supporters of 

 this theory." Dieckerhoff, Lafosse, and Hoffmann believe the 

 disease originates in the bursa of the cunean branch of the flexor 

 metatarsi. 



Anacker, Joly, Moller, Schiitz, and Smith believe spavin to be an 

 arthritis chronica deformans. The view that the articular surfaces 

 are first invaded was held by Bouley, Dieterichs, Gurlt, Havemann, 



