640 ,p j NAVICULAR DISEASE. , ' 
ABa ^ ^ Cn4l Jur J i~ tCU^° 
hollow of the heel. In doubtful cases Brauell recommends working: 
the horse after applying a bar-shoe, the bar of which covers the centre 
of the frog. This increases the lameness in real cases of navicular 
disease. 
In some cases forcible dorsal flexion gives pain. The foot is lifted 
as in shoeing, and the toe pressed slowly and powerfully downwards, 
or the horse is so placed that its toe rests on an elevation, thus causing 
the heels to be abnormally low when weight is placed on the foot. The 
same thing often occurs accidentally when the horse is moved on uneven 
ground, and produces very marked lameness. 
As a rule, there is no increased warmth or pulsation. Brauell and 
Haubner have drawn attention to the erroneous view advanced by 
English authors, viz., that increased pulsation was a symptom of this 
disease ; Hausmann, indeed, views absence of pulsation as pathognomonic 
of the disease in question. As already stated, other diseases associated 
with increased pulsation, such as contracted sole, 1 are often mistaken 
for navicular disease ; but as there is no acute inflammation, the absence 
of increased warmth and marked pulsation are not surprising. 
During the further course of the disease the hoof contracts, and the 
heels become longer and narrower. These changes in size and form 
suggested to Sticker the invention of a podometer—an instrument, 
however, which is of no particular value for diagnosis, and can be easily 
replaced by the meter used for measuring the angle of the hoof. 
As the patient no longer places weight on the foot, local nutrition and 
horn production suffer, the hoof contracts, and the coronary band 
appears more prominent, and seems swollen. The uprightness of the 
pastern causes the hoof to take a more perpendicular position as time 
goes on. The frog is also relieved of pressure, and this, with the defective 
development of the hoof, leads to shrinking in of the heels and atrophy 
of the frog—in short, to contraction of the foot, the horn sole then 
appearing abnormally concave. 
I hat all these changes are due to diminished pressure and movement 
of the hoof is shown by the fact already pointed out, that they gradually 
disappear after operations like neurectomy, which relieve the pain and 
remove the lameness. 
Although contraction of the hoof is important in diagnosis, it should 
never alone be relied on, because, as Haubner pointed out, the left foot 
is often smaller than the right. 
The quality of the horn also suffers during the disease. The wall 
frequently appears uneven, rough, or covered with rings, and its horn 
brittle. 
1 For fuller particulars of the changes in the foot incidental to navicular disease see 
“A Handbook of Horse-shoeing,” by Dollar and Wdieatley, pp. 840, 355 et seq. 
