426 



Journal of Agriculture. 



[8 July, 1907. 



8 in. by 6 in., .sloping backwards at an angle of about 18 deg. so that 

 the toe is elevated. The tendon is by this means put upon the stretch 

 and causes pressure on the navicular bone, which pressure will be increased 

 if the opposite foot is lifted. On this being done if the horse is affected 

 with navicular disease he shows acute pain and endeavours to get away. 

 Some horses may show discomfort from the position in which the foot is 

 placed, apart from the presence of pain and it is therefore prudent to- 

 make a comparison with the same method on the opposite foot. 



The disease seldom occurs in horses under five years old. It is slow 

 in developing and many of the characters above described are so gradually 

 manifested as to render the diagnosis a matter of very great difficulty. 

 The negative evidence afforded by the absence of other causes of lameness 

 is of value in coming to a conclusion but oftentimes it will be found more 

 satisfactory to apply the cocaine test as described on page 58. 



A horse affected with navicular disease is always a dangerous animal 

 to ride, on account of his great liabilitv to stumble. He is apparently 

 afraid to lift his feet to a suflficient height to avoid stumbling, because 

 of the fact that the higher the foot is raised the greater is the shock on 

 the heels, and the greater therefore is the pain experienced, when the heels- 

 are brought to the ground. 



Fig. 71. Attitude when " pointing." 



Treatment. — When navicular disease is su.spected, some good may- 

 be done towards arresting its progress by removing the shoes and rasping 

 the ground surface of the wall so as to give frog pressure before turning 

 the horse out for a spell on. soft lowland pasture. But once the disease is 

 established no treatment has yet been suggested that has any curative 

 effect. The palliative effect of blistering round the coronet is evanescent. 



The lameness may be modified somewhat by shoeing with a broad- and 

 thick-heeled shoe, but for its complete removal the onlv method of any 

 value is the operation of neurectomy (see page 68). This operation (the 

 cutting out of portion of the sensory nerve of the foot) will enable a horse 

 with navicular disease to be used for a considerable time but it does not 

 stay the progress of the disease. It merely removes the lameness and by 

 obliterating the pain renders the horse less liable to stumble and therefore 

 safer to ride. A horse operated on by the author some vears back was 

 regularly hunted for three .seasons afterwards and seemed good for another 

 three until one day he unexpectedly flung off one of his hoofs and had ta 

 be destroyed. 



For other diseases of the foot — those in which the cause of lameness- 

 (if any) is obvious- — see chapter on Diseases of the Foot. 



(To he coui'niucd.) 



