*Because compensatory lameness is not due to pain, it is generally expected that the lameness will resolve when the primary lameness is blocked out. In this case, the primary lameness is just as likely to be forelimb or hindlimb. There is an additional exception to the law of sides when the hindlimb lameness is ipsilateral and exclusively impact type. Therefore, horses with primary forelimb lameness can appear to have contralateral hindlimb pushoff lameness (most common), and/or ipsilateral hindlimb impact lameness. This gives the appearance of an ipsilateral hindlimb lack of impact. When the horse lands on the ipsilateral hindlimb to the primarily lame forelimb, the pelvis falls a normal amount, which is comparatively less than on the opposite hindlimb. This gives the appearance of a contralateral hindlimb lack of pushoff.Ĭaveat: Sometimes the horse with a primary forelimb lameness will shift weight back onto the opposite side hindlimb, loading that limb more than it normally would. Contralateral PrincipleĪ horse with primary forelimb lameness may pushoff with less force in the opposite hindlimb in order to reduce the load on the painful forelimb. The Ipsilateral PrincipleĪ horse with primary hindlimb lameness will shift weight forward onto the opposite forelimb when trotting, causing the horse to load that limb more than if not lame in the hindlimb.īy loading the opposite forelimb more than it normally would, this gives the appearance, in the next half of the stride cycle of an apparent ipsilateral forelimb lameness because comparatively the head moves down normally, which is less than in the forelimb opposite the primarily lame hindlimb. The “Law of Sides” explains the patterns. We know less about secondary lameness, derived mostly from clinical observation. Not all horses show compensatory lameness, but most do, and some compensate greatly. It is easy to suddenly create lameness in a forelimb or hindlimb for a short time and we can see the disappearance of compensatory lameness when a primary lameness is blocked out. We know a lot about compensatory lameness in the trotting horse, because we can study and test it easily. Secondary Lameness – compensatory movement to offload a limb with pain causing overload of a second limb, ultimately leading to pain in that second limb.Compensatory Lameness – compensatory movement to offload a limb with pain creating asymmetric movement (but not due to pain) in the opposite end of the body.In order of most to least common the reasons are: We can use this principle to help sort out multiple limb lameness using what we know about compensatory movement (lameness due to offloading the primary limb) and what we suspect about secondary lameness due to chronic overload in a second limb.ĭisregarding causes of lameness that are frequently bilateral – like navicular disease and distal tarsal osteoarthritis – there are three reasons why a horse will show lameness in more than one limb. What does this have to do with equine lameness? It is also known as “the principle of parsimony”, which states a general scientific maxim offered by most great scientists before and after Ockham – including Ptolomy, Newton, and Einstein. (In this context, “razor” means principle not a sharp cutting tool). Ockham’s Razor, translated (roughly) as “more things should not be used than are necessary”, is attributed to a 14th century friar/philosopher, William of Ockham. įirst Published: “Entia non sunt multiplicanda praetor necessitatum.”
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