Introduction

• Pain or mechanical dysfunction in the musculoskeletal system can → alterations of gait, manifest as lameness or poor performance.
• Evaluation of changes in the normal gait, although a subjective process, is an essential part of diagnostic work up for lameness following examination of the horse at rest Musculoskeletal: physical examination - adult.
• Neurologic dysfunction may also → abnormal gait.
• Subtle and/or bilateral lameness can be very difficult to identify.
• Changes in behaviour, and facial expression may also indicate the presence of pain.
• Soundness in a straight line does not preclude the presence of pain causing lameness or poor performance.
• It is important to bear in mind that clinical signs are frequently seen distant to the source of pain. For example hindlimb lameness often causes thoracolumbar stiffness in the absence of primary back pain, or a reluctance to bend in one direction in the absence of primary neck pain or pathology.
• Following examination at rest Musculoskeletal: physical examination - adult and evaluation of conformation Musculoskeletal: conformation.

Uses

• Lameness evaluation.
• Poor performance evaluation.
• Neurological examination.
• Prepurchase examination Pre-purchase examination.

Grading

• The severity of lameness can be graded to allow subjective characterization, which can be used for comparison of lameness over time, following diagnostic analgesia or after treatment/therapy.
• The severity of lameness can be highly variable under different circumstances, e.g. walk versus trot, straight lines versus circles.
• Some grading scales, eg the commonly used American Association of Equine Practitioners (AAEP) scale, do not permit the grading of lameness under different circumstances independently.
• When used correctly, the AAEP scale is likely to be misleading and insensitive.
• A numerical rating scale which can be combined with description/qualification of the gait, and applied under different circumstances (in hand, lunge, ridden, etc) has been proposed as a superior system:
  • Grade 0 - no lameness detected.
  • Grade 2 - mild lameness.
  • Grade 4 - moderate lameness.
  • Grade 6 - severe lameness.
  • Grade 8 - non-weightbearing.
• The characteristics of lameness under different circumstances should be described, eg the stride length, height of step, presence of toe drag, body lean angle on the lunge and fetlock excursion (dropping).
• Other potential indicators of pain should also be noted, such as tail swishing, evasive or conflict behavior, ears pinned back, etc.

Advantages

• Inexpensive.
• Non-invasive.
• Essential for identification of the lame(r) limb(s).
• Essential for identification of significant rider or tack factors.
• Influences prognosis.
• Can be repeated to assess the response to diagnostic analgesia or following therapy.

Disadvantages

• Subjective.
• Reliant on observer experience.
• The interobserver agreement is variable, particularly for hindlimb and subtle lameness.
• Bilateral, hindlimb and subtle lameness can be difficult to identify, especially for inexperienced veterinarians.
• Few causes of lameness have gait abnormalities which are pathognomonic.
• The vast majority of clinical signs are non-specific.

Requirements

Preparation

Procedure

Further Reading

Publications

Refereed papers

• Recent references from PubMed and VetMedResource.
• Hammarberg M, Egenvall A, Pfau T & Rhodin M (2016) Rater agreement of visual lameness in horses during lungeing. Equine Vet J 48 (1), 78-82 PubMed.
• Barstow A & Dyson S (2015) Clinical features and diagnosis of sacroiliac joint region pain in 296 horses: 2004-2014. Equine Vet Educ 27 (12), 637-647 VetMedResource.
• Pfau T, Fiske-Jackson A & Rhodin M (2015a) Quantitative assessment of gait parameters in horses: useful for aiding clinical decision making? Equine Vet Educ 28 (4), 209-215 VetMedResource. 
• Pfau T, Boultbee H, Davis H, Walker A & Rhodin M (2015b) Agreement between two inertial sensor gait analysis systems for lameness examinations. Equine Vet Educ 28 (4), 203-208 VetMedResource.
• Greve L & Dyson S J (2013) An investigation of the relationship between hindlimb lameness and saddle slip. Equine Vet J 45 (5), 570-577 PubMed.
• Dyson S (2011a) Can lameness be graded reliably? Equine Vet J 43 (4), 379-382 PubMed.
• Keegan K et al (2010) Repeatability of subjective evaluation of lameness in horses. Equine Vet J 42 (2), 92-97 PubMed.
• Hewetson M, Christley R, Hunt I & Voute L (2006) Investigation of the reliability of observational gait analysis for the assessment of lameness in horses. Vet Rec 158 (25), 852-858 PubMed.
• Dyson S, Murray R, Schramme M & Branch M (2004) Collateral desmitis of the distal interphalangeal joint in 18 horses (2001-2002). Equine Vet J 36 (2), 160-166 PubMed.
• Licka T, Kapaun M & Peham C (2004) Influence of rider on lameness in trotting horses. Equine Vet J 36 (8), 734-736 PubMed.
• Dyson S & Murray R (2003) Pain associated with the sacroiliac joint region: a clinical study of 74 horses. Equine Vet J 35 (3), 240-245 PubMed.
• Buchner H H F, Savelberg H H C M, Schamhardt H C & Barneveld Q (1996) Limb movement adaptations in horses with experimentally induced fore- or hindlimb lameness. Equine Vet Educ 28 (1), 63-70 PubMed.

Other sources of information

• Baxter G M (2011) Ed. Adams and Stashak’s Lameness in Horses. 6th edn. Wiley & Sons.
• Dyson S (2011b) The Elbow, Brachium and Shoulder. In: Diagnosis and Management of Lameness in the Horse. Eds: Ross M W & Dyson S J. Elsevier Saunders, USA. pp 427.
• Ross M W & Dyson S J (2011) Diagnosis and Management of Lameness in the Horse. 2nd edn. Elsevier Saunders, USA.
• Dyson S (2002) Lameness Associated with Stifle and Pelvic Regions. In: Proc AAEP Annual Convention. pp 387-411.