Page 530 - Adams and Stashak's Lameness in Horses, 7th Edition

496 Chapter 4

commonly characterized by a rapidly progressing cata- the Obel grading system does not describe all cases of
strophic failure of the lamellae (with extensive separa- laminitis (it appears to be primarily based on cases of
VetBooks.ir rapid displacement of the distal phalanx. Earlier signs of both the clinics and when describing time points assessed
SRL), it is still used to describe the degree of lameness in
tion of the dermal and epidermal lamellae), resulting in
in laminitis research.
a milder lameness may not be apparent due to the lame-
ness already present on the opposite limb. Clinical signs of SRL are most commonly observed
24–72 hours following the onset of a septic disease pro-
CLINICAL SIGNS: THE ACUTE ONSET cess. The onset of disease in endocrinopathic laminitis is
extremely variable; whereas an insidious, “subclinical”
OF LAMINITIS displacement of the distal phalanx may take place over
The clinical signs assessed in laminitis mainly refer to months to years in the horse with EMS, pasture‐associ-
the degree of lameness noted and the digital exam. The ated laminitis may exhibit an acute and severe onset
lameness varies in severity from being barely detectable similar to SRL. In SLL, disease progression is extremely
to an animal that is recumbent the majority of the time inconsistent between animals, with clinical signs of SLL
secondary to digital pain. Due to this variability, Obel occurring within days, weeks, or months after the onset
introduced a grading system to describe the degree of of excessive weight‐bearing in the affected digit.
lameness (Table 4.2) more than 60 years ago. Although The clinical signs of acute laminitis are characterized by
lameness, an increase in the temperature of one or more
hooves, increased digital pulses, and elicitation of a pain-
Table 4.2. Obel grades of laminitis. ful withdrawal response to hoof testers. In EMS and sep-
sis, the forelimbs are most commonly affected (most likely
due to more weight being borne by the forelimbs); the
Grade Associated lameness and gait abnormalities hindlimbs may also be involved (usually in severe septic
cases). SLL occurs on the supporting forelimb or hindlimb
1 At rest the horse alternately and incessantly lifts the feet, opposite the non‐weight‐bearing limb. The characteristic
often at intervals of a few seconds. Lameness is not evident stance of a laminitic horse with both forefeet affected is
at the walk, but a short stilted gait is noted at the trot
placement of the forefeet well in front of the normal posi-
2 The horse moves willingly at a walk, but the gait is stilted. tion and anterior placement of the hindfeet in order to
A foot can be lifted off the ground without difficulty shift more weight to the hindlimbs (Figure 4.70). 37
The characteristic gait of a laminitic horse is stiff limb
3 The horse moves very reluctantly and vigorously resists movement while maintaining the same laminitic posture
attempts to have a foot lifted off the ground of both fore‐ and hindlimbs being placed anteriorly.
Horses in which all 4 feet are affected may have a
4 The horse refuses to move and will not do so unless forced
more normal stance or may appear “camped out” with

Figure 4.70. Classic stance of a horse with laminitis with the forelimbs placed abnormally far forward and weight shifted toward the
hindlimbs. Source: Courtesy of L. Brandstetter.