BODY CONFORMATION OF THE HORSE IN RELATION TO LAMENESS

BODY CONFORMATION OF THE HORSE IN RELATION TO LAMENESS

 

This module deals with

·Conformation

·Lameness and its classification

·Grading the lameness

CONFORMATION

·The conformation of the horse is the key to its method of progression. Poor conformation of limbs contributes to certain lamenesses.

Conformation of the forelimb

·The forelimb bears 60 to 65 % of the weight of the horse.

·The forelimbs are subjected to more injuries from concussion and trauma than the hindlimbs because the forelimbs not only bears weight if the body in the movement, but also aid the hindlimbs in propelling the body.

FAULTS IN THE CONFORMATION

Faults in the conformation of the forelimbs

• Base narrow
• Base wide
• Toe in or pigeon toed
• Toe out or splay footed
• Base narrow and toe in
• Base narrow and toe out
• Base wide and toe in
• Base wide and toe out
• Plaiting
• Calf knees
• Camped in front
• Short upright pastern
• Long sloping pastern
• Long upright
• Bucked knees or knee sprung
• Carpus valgus (medial deviation of carpus)
• Carpus varus
• Open knees
• Ofset or bench knees
• Tied in knees
• Cut out under the knees
• Standing under in front

Faults in conformation of hind limbs

• Base wide
• Tarsus valgus/ cow hock
• Sickle hock
• Straight behind
• Straight under behind
• Camped behind

GRADING THE LAMENESS

Grade I

·Lameness is not observed in walk but recognizable in trot. Forelimb- head and neck movements will be evident, but not in the hind limb.

·Hind limb- mild asymmetry in the gluteal rise will be noticed.

·Observed in chronic, non progressive disease causing lameness.

Grade II

·An alteration in gait is noticed at a walk but no evident head movements associated with it.

·At trot the lameness becomes obvious with head and neck movements are evident.

·Hind limb- A greater degree of asymmetry of gluteal rise and shortened duration.

Grade III

·Lameness is evident at walk and trot. Head lifting during weight bearing is the prominent feature of the forelimb.

·In hind limb head nodding when the opposite forelimb hits the ground while trotting is obvious

Grade IV

• A non weight bearing lameness is present.

RELATIONSHIP BETWEEN CONFORMATION AND LAMENESS

·Poor conformation of limbs contributes to certain lamenesses, for example base narrow forelimbs lead to interference and may predispose to side bone.

DEFINITION AND DISEASES OF LAMENESS

Definition

·Any structural or functional disorder of locomotor system is called lameness. These may be congenital or acquired in nature and may be caused by a variety of etiological agents such as trauma, poor conformation, defeciency of calcium, phosphorus, vitamin A, D or E, infection, metabolic disorders, circulatory or nervous disorders, etc.

Diseases

• Gonitis
• Rupture
• Fibrotic myopathy
• Stringhalt/ Springhalt
• Chondromalacia of the patella
• Thorough pin 
• Spavin
• Curb and Capped hock
• Ulceration of sole,Interdigital fibroma and sore shin
• Ring, side and navicular bone
• Pyramidal and Sand crack
• Fractures
• Canker and Corn
• Paralysis
• Bicipital bursitis and Omarthiritis
• Knee
• Wind puff/ Wind gull, Osselets and Septic arthritis 
• Ostochondritis dissecans and degenerative joint disease 
• Laminitis and Hoof avulsion 

Classification

·Supporting limb lameness

o    This is evidenced when the horse supports the weight on the foot.

o    e.g., injury to bones, joints, collateral ligaments

·Swinging limb lameness

o    This is evident when the limb is in motion.

o    e.g., pathologic changes involving joint capsules, muscles, tendons, and tendon sheaths.

·Mixed lameness

o    This is evident both when the limb is in motion and when it is supporting the weight.

·Complementary lameness

o    Pain in one limb cause uneven distribution if weight on the another limb or limbs which can produce lameness in lameness in previously sound limb.

Diagnosis of lameness

• Anamnesis
• The questions to be answered in the anamnesis:
• How long the horse been lame?
• Has the horse been rested or exercised during the lameness period?
• What caused the lameness?
• Does the horse warm out of the lameness?
• Does he stumble?
• What treatment has been done and was it helpful?
• When was the horse shoed?
• Procedure for examination
• Visual Examination
• At rest
• Careful visual examination from a distance and then close up
• Conformation, body condition, alteration in posture, weight shifting and pointing is noted.
• At exercise
• Gait of all limbs should be observed from a distance. This is done to identify the limb(s) involved, the degree of lameness and in-coordination of in movement.
• Handle the horse during the exercise
• Should not be held loose to avoid head and neck swaying from one to another which will create asymmetric gait.
• If the head is held tight the nodding during the gait will be difficult to observe.
• Selection of the surface
• Hard surface is preferred for the lameness evaluation
• The unsound foot makes less noise because less weight is taken on that foot.
• Gravel surface is preferred for evaluation of sole and frog.
• Forelimb
• As the result of lameness of forelimb, the head will drop when the sound foot lands and rises when weight is placed on the unsound foot or limb.
• Hind limb
• The head and neck movements can be best appreciated from the side in the trotting gait.
• In moderate and severe lameness, the head and neck will rise as the unaffected limb contacts the ground and lowers when the unsound limb contacts the ground.
• Examination by palpation and manipulation
• Palpation is started from the bottom and complete examination of the limb should be done.
• Size and shape of the lame foot should be compared with the normal opposite member.
• Each part of the limb is manipulated and palpated for any abnormality and pain perception.
• Local Anaesthesia

o    Local anaesthetic solutions are infiltrated in suspected limb for the diagnosis of lameness

• Types of local anaesthesia
• Perineural infiltration
• Field block
• Direct infiltration of a sensitive region
• Intra-synovial anaesthesia

Other diagnostic procedures for lameness

• Radiography
• Arthroscopy
• Scintigraphy
• Thermography

SYMMETRY OF HOOF PAIRS

·Generally, the toe length of a hoof should be equal to that of its counterpart.

·Variation in hoof angle, however, often occurs in paired limbs because of individual limb conformation.

·In some horses, the difference should be minimized through trimming and shoeing; but in many animals, the mismatched hooves should be allowed to be different.

·Dynamic balance may indicate which path the farrier should choose.

·The hoove will be trimmed and shod differently so that they move the same.

·There is a normal difference in shape and hoof angle between forefeet and hindfeet.

·The forefeet are usually larger, rounder, and wider at the heels and have flatter soles than the hindfeet. Hindfeet are commonly one shoe size smaller, are more pointed at the toe, and have a more convcave sole and higher hoof angle.