Diagnosing limb paresis and paralysis in sheep

Abstract

Paresis and paralysis are uncommon problems in sheep but are likely to prompt farmers to seek veterinary advice. A thorough and logical approach can aid in determining the cause of the problem and highlighting the benefit of veterinary involvement. While this may not necessarily alter the prognosis for an individual animal, it can help in formulating preventive measures and avoid the costs – both in economic and in welfare terms – of misdirected treatment. Distinguishing between central and peripheral lesions is most important, as the relative prognoses are markedly different, and this can often be achieved with minimal equipment. This article describes an approach to performing a neurological examination of the ovine trunk and limbs, the ancillary tests available and the common and important causes of paresis and paralysis in sheep.

CRISPR/Cas9 mediated generation of an ovine model for infantile neuronal ceroid lipofuscinosis (CLN1 disease)

“…Visual function was assessed via remote observation of navigation and visual tracking alongside menace response testing, whilst pupillary light and dazzle reflex testing was used to assess subcortical responses to light and glare, respectively 16,19,20 . By 12 ± 1 months of age, homozygote sheep were observed bumping into obstacles followed by a significant deficit in the menace response by 17 ± 1 months at the humanely defined endpoint (Supplementary Fig.…”

“…2). Motor performance and vestibular system integrity were assessed remotely by observation of gait and balance, followed by direct testing of conscious proprioception using hoof placement, knuckling and hopping tests, and balance via a ‘push test’ 20 . There was a significant increase in proprioceptive deficit in the homozygote sheep (Supplementary Fig.…”

“…Assessments included hands-off observation of mentation, behaviour, gait, balance, and navigation, followed by a general physical examination and full neurological examination as described by Crilly et al . 20 (See Supplementary Fig. 2).…”

Establishment of a Sheep Model for Hind limb Peripheral Nerve Injury: Common Peroneal Nerve

“…The test can be difficult to perform on nervous, aggressive and uncooperative animals, and since sheep do not easily tolerate their limbs being manipulated, results are not always easy to interpret. A good alternative is a dynamic positioning test, in which the animal's limb is placed on a mobile platform (plastic, piece of wood), the platform being moved slowly away from the animal, determining the time it takes to reset the member in its original position (58). Other postural reactions such as hopping tests, hemiwalking tests and visual and tactile placement tests are only easy to perform on young or small adult animals (57,58).…”

“…In a normal withdrawal reflex, the animal should move the limb away from the painful stimulus by showing awareness through vocalization or by looking at the tested limb. If the animal does not respond initially, an increase in stimulus intensity should be tested before considering the reflex to be absent (50,57,58) Pain may be difficult to assess in sheep as they are tendentially stoic animals. Once there is no specific method for determining the presence of pain, signs should be observed during the remaining neurological examination, indicating the presence of pain perception.…”