When an animal is made to travel in a circle, when a member affected with supporting-leg-lameness is on the inner side of the circle, lameness is accentuated because weight is borne by the lame leg for a greater length of time, the result of such circuitous manner of locomotion. In swinging-leg-lameness, on the other hand, because pain is increased at the time an affected member is being advanced, lameness is increased when the subject is made to travel in a circle, with the lame leg on the outside of a circle thus described.
In supporting-leg-lameness, the transientness of the weight-bearing period upon the affected member is the determining factor in the production of lameness. This unequal period of weight-bearing upon the front legs, for instance, causes an acceleration in the advancement of the sound member, in order to relieve the diseased one which is bearing weight. In other words, when an animal that is affected with supporting-leg-lameness travels in a straight line, since weight is borne by the diseased leg for an abnormally short period of time, the sound member needs be in the act of advancement a correspondingly short period. The result is then, an unequal division of stride; a nodding of the head with the catching up of weight by the sound leg,—in front leg affections—and this is termed limping.
With continuous exertion as in travel for a considerable distance, in some cases, lameness becomes less evident—as in spavin. This “warming out” process is due in a measure to the parts becoming less sensitive upon exertion, and is to be seen, to a limited extent, in all inflammatory affections that are not too severe; consequently, in some cases, examination of a lame animal should begin in the stall, for in instances where the impediment is not marked, there may be no evidence of lameness after the subject has walked a few steps. In other cases, lameness increases as the subject continues to travel, and often to the extent that the impediment becomes too severe to allow the animal being serviceable. Therefore, one can not, in every case of lameness observed, positively determine the gravity of the situation, without having seen the affected animal in action for a sufficient length of time to understand the nature of the condition existing. This necessitates driving the animal for several miles in certain cases.
Sometimes it is impossible to arrive at any definite conclusion, as the result of a single examination, and it then becomes necessary to see the subject again at a later date, or under more favorable circumstances. This is to be expected in some conditions where there exists rheumatic affections, and also in some foot diseases.