Fig. 5. Right forelimb with left hindlimb impact and pushoff CFHL.
lack of pushoff, and ipsilateral hindlimb lame- ness that is lack of impact. This pattern was not very common, comprising only about 7% of all cases. About two thirds of these cases had the primary cause of lameness in the forelimb and about one third in the hindlimb. The simplest ex- planation for the CFHL is primary forelimb lameness with compensatory contralateral hind- limb lack of pushoff and ipsilateral hindlimb lack of impact. An alternative explanation for this pattern is primary hindlimb lameness (lack of pushoff) and secondary contralateral forelimb and hindlimb lameness (Fig 8).
Most CFHL patterns seen during the initial
straight-line trotting evaluation are easily explained by compensatory movement principles, and this knowledge is useful for localization of primary limb lameness in many cases. However, CFHL patterns in which hindlimb lameness is only of the impact type
suggest that the diagnostic process will be more difficult.
3. Ipsi-Impact vs. Ipsi-Pushoff
In a second “big data” study, cases were either ipsi- pushoff (CFHL with forelimb lameness and ipsilat- eral hindlimb lameness that is only lack of pushoff) or ipsi-impact (CFHL with forelimb lameness and ip- silateral hindlimb lameness that is only lack of impact). These 2 patterns correspond to patterns 2 and 3 above. As was found earlier (see above), pattern 2 cases were more likely to have a primary hindlimb lameness, and thosewith pattern 3were just as likely to have primary forelimb as primary hindlimb cause of lameness. However, interestingly, if the cause of lameness was found in a forelimb, it was more likely to be navicular disease in ipsi-impact cases and more likely to be in the foot for ipsi-pushoff cases compared to ipsi-impact cases. Alternatively, if the cause of lameness was found in a hindlimb, it was more likely
Fig. 6. Right forelimb with only left hindlimb pushoff CFHL. 352 2022 / Vol. 68 / AAEP PROCEEDINGS