No. 7. DEPARTMENT OF AGRICULTURE. 647 



thorough-bred stallion once and four times to a hackney. Most of the 

 colts were unusually good. Two, at least, were show horses. All of 

 them developed into sound saddle and harness horses, worked hard 

 and none of them ever showed a symptom of navicular disease. On the 

 other hand, equally convincing cases that showed a hereditary tend- 

 ency were cited by other veterinarians. It may require months to 

 make a positive diagnosis of navicular disease and it is then best com- 

 pleted by an autopsy. The condition is practically incurable, and in 

 advanced cases, neurectomy is the only means by which the animal's 

 usefulness maj' be prolonged. 



Cadiot reports that out of 4()o horses brought to the Alfort clinic 

 from 1896 to 1897, 108 were suffering with different affections of the 

 feet and navicular disease was diagnosed in six. Probably about one 

 per cent, of a veterinarian's practice will be navicular disease. Con- 

 tracted sole may show practically the same symptoms and is often 

 associated with it. Contracted solo is curable in uncomplicated cases 

 and the animal can be restored to soundness. The Australian law 

 does not list navicular disease as transmissible. 



It is most often seen in well-bred horses ; in draft horses, seldom, 

 and it appears usually in the front feet, and most often in horses with 

 deep, steep contracted heels, yet it is often seen in feet of the best 

 conformation and has been found in the hind feet. 



The causes mentioned by Moller are heredity, traumatisms and 

 metastases. As metastic causes, diarrhoea, various general infections 

 as strangles have been suspected. Direct violent traumatisms may 

 play a small part in the production of the disease but the usual cause 

 is the traumatism of wear; the pounding and strain of hard work. 



The pathology of the disease is fairly well understood, but as to 

 cause, prevention and treatment, there is still much to be learned. 



It would appear just to condemn, for breeding purposes, horses 

 afflicted with this disease where it has developed from small cause, 

 where it is of long standing and both feet are affected. 



Osteoporosis is one of the listed hereditary unsoundnesses in the 

 Australian law. From observations made in this country, it could 

 not be so considered. Many cases sent to the country recover, and 

 so far as could be learned, no outbreaks have occurred in sections 

 to which such cases have been sent. 



Several bad cases of big head in fillies were sent to Mr. Henry 

 Fairfax, in Virginia, from near Philadelphia. All made a com])lete 

 recovery by the time they were five years old. They Avere regularly 

 bred, and the disease never appeared in their colts on the farm. 



If Osterporosis is due to infection or malnutrition, ns many inves- 

 tigators believe at" present, there is no reason for considering it hei'edi- 

 tary. The evidence is, however, strong in favor of the theory of in- 

 fection, and warrants breeders in isolating or destroying well marked 

 cases. 



The following quotation from an article written by M. J. Passet of 

 the Alfort School and printed last year in the R<^ceeil de Jfedecine 

 Veterinaire, on the subject of "Osteomalacia," will show the opinions 

 held in reference to big head in Europe. It is as follows: '^Osleo- 

 malacia is common in man, horse, ox, goat, sheep, swine, dog, rabbit 

 and rat. 



The disease is known bv various names which change with invest!- 

 gators according to the way that the symptoms and alterations strike 



