HORSE— CARE AND MANAGEMENT. 



and coronal bones, that part will be greatly 

 thickened and inflamed, the tendon being 

 often adherent to it. In the healthy con- 

 dition there ought to be no adhesion of the 

 fibres of the tendon to any part of the 

 navicular bone but its postero-inferior 

 •edge, to which the tendon is fixed by some 

 few fibres, the bulk passing to be inserted in 

 the os pedis. The posterior face of the na- 

 vicular bone should be beautifully smooth, 

 and lined by synovial membrane, which 

 forms a lubricating sac for it to play upon, 

 and thus take off the friction between the 



Fig. 27. — Ulceration of the Posterior 

 Surface of the Navicular Bone. 



1. Lower or plantar surface of pedal bone. 



2. Small specks of exostosis. 



3. Carious patch. 



tendon and the bone. Such is nature's 

 provision against mischief in this delicate 

 part of the machinery of the foot, which 

 she keeps in order by the constant supply 

 of synovia or joint oil. But when the 

 sac is not stimulated to a healthy action 

 by the pressure of the frog below it in- 

 doors and out, synovia is no longer se- 

 creted in proper quantity, and as soon as 

 the horse is put to hard work, inflamma- 

 tion takes place for want of it. The re- 

 sult is some one of the consequences of 

 inflamed joints. Either ulceration takes 

 place in the postero-inferior surface, where 

 the tendon glides over it as shown in fig. 

 27 (at 3), sometimes ending in caries of 

 the bone itself; or adhesion takes place 

 without ulceration of the tendon with the 

 surface of the bone, or there are small 

 exostoses thrown out, see fig. 27 (2); or 

 lastly, there is simple inflammation with- 

 • -out either adhesion or ulceration, and in 



this stage the disease is amenable to treat- 

 ment without leaving any trace behind. 



The symptoms of navicular disease are 

 the same, whether the mischief has ex- 

 tended to ulceration or not ; but the his- 

 tory will guide us in ascertaining how far 

 it has gone. Of course they vary in de- 

 gree, for there may be only a slight extent 

 of ulceration, or a high degree of simple 

 inflammation ; but in the former case the 

 lameness will not be so marked as in the 

 latter, though the prospect of recovery 

 will be much less. There is always more 

 or less lameness ; but, in consequence of 

 its affecting both feet, it is not so marked 

 to the careless observer as in some much 

 more trivial cases where only one is dis- 

 eased. The distinguishing sign, though 

 not absolutely infallible, is the pointing of 

 the toe, and a peculiar rounding forward 

 of the fetlock joint, so as to relieve the 

 navicular bone of any weight. In 1am- 

 initis, the object of the sufferer is to re- 

 lieve all pressure as much as possible, by 

 bringing the hind legs under the body, 

 and by bearing the weight of the fore 

 quarter on the heels. Here, the reverse 

 of the latter attitude is observed — the 

 heels are not allowed to take any pressure, 

 and the toes alone are placed at all firmly 

 on the ground. This is marked in the 

 stable by the pointing of the toe (in each 

 foot alternately, if both are diseased, but 

 in the one only, if they are not both 

 affected). Out of doors, the toes dig into 

 the ground, the heel never being brought 

 firmly down; and frequent stumbles mark 

 the difference between this species of 

 lameness and laminitis. The subject of 

 navicular disease generally walks sound ; 

 but the moment he is trotted, he goes as 

 if his legs were tied together, his stride 

 being shortened in a remarkable manner, 

 but without exhibiting the peculiar fum- 

 bling gait of the foundered animal. As 

 in his case, soft ground suits him, and he 

 has no fear of plough, because his sole is 

 hard and unyielding. Many tolerably 

 confirmed cases of navicular disease may, 

 therefore, be driven, except when the 

 ground is hard, supposing, of course, that 

 they are kept off the road ; but no plan 

 of management will enable them to bear 

 the jars incidental to harness-work or 

 hacking. When one foot only is the sub- 

 ject of navicular disease, it often hap- 

 pens that it is smaller altogether than the 



