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Foot: flexural deformity – hyperextension
Synonym(s): Flexural deformity, Flaccidity of the flexor tendons
Introduction
- Cause: congenital or acquired laxity in flexor tendons.
- Signs: bilateral hindlegs, or all limbs affected.
- Diagnosis: physical examination, radiography.
- Treatment: farriery, exercise, protective bandages.
- Prognosis: good.
Print off the factsheet on Flexural limb deformities to give to your clients.
Presenting signs
- Congenital condition present at birth usually affecting both hindlimbs or less commonly all four limbs.
- Acquired condition seen in foals and adults that have a limb(s) in a cast, splint or heavy bandage.
Acute presentation
- Present at birth.
Age predisposition
- Neonatal or young foals.
Breed/species predisposition
- Friesian Friesian.
- Heavy horse or draft breeds Irish Draught.
- Thoroughbred Thoroughbred.
Cost considerations
- Cost of treatment, including corrective farriery.
Pathogenesis
Etiology
- The exact etiology in unknown in the congenital form but may involve a physiological variation or a temporary failure of agonist/antagonist muscle balance. Spontaneous correction with normal exercise in most cases further suggests this as the underlying problem.
- The condition is often more common and severe in foals that are premature, dysmature and/or systematically ill Reproduction: prematurity / dysmaturity.
- Lack of exercise in young foals may exacerbate existing weakness or cause failure to resolve.
- Acquired condition is a rare complication of prolonged casting, splinting or bandaging, especially in foals and young animals, particularly if the foot has been included Musculoskeletal: external fixation – casts.
- Flaccidity or weakness of the flexor tendons is a common condition in newborn foals but the more severe form of the problem, sometimes called digital hyperextension, is rare.
Predisposing factors
General
- Systemic illness in young foals.
Specific
- Prolonged casting or splinting of distal limb Musculoskeletal: external fixation – casts.
Pathophysiology
- Increased extensibility in flexor tendons → overextension of interphalangeal joints, fetlocks, hocks +/- other joints → failure to correctly weightbear on foot → abnormal foot wear (rocker heel) further exacerbating the deformity; possible soft tissue damage due to weightbearing on palmar/plantar aspect of fetlock.
- Congenital: unknown.
- Acquired: prolonged absence of weight bearing due to cast or illness → weak tendons.
Diagnosis
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Treatment
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Outcomes
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Further Reading
Publications
Refereed papers
- Recent references from PubMed and VetMedResource.
- O’Grady S E (2017) Routine trimming and therapeutic farriery in foals. Vet Clin North Am Equine Pract 33 (2), 267-288 PubMed.
- Boerma S, Back W & Sloet van Oldruitenborgh-Oosterbaan M M (2012) The Friesian horse breed: A clinical challenge to the equine veterinarian? Equine Vet Educ 24 (2), 66-71 VetMedResource.
- Kelmer G & Kramer J (2006) Deep digital flexor tendon shortening as a treatment for distal interphalangeal joint hyperextension in a 2-year-old mare. Vet Comp Orthop Traumatol 19 (4), 250-254 PubMed.
- Curtis S J & Stoneham S (1999) Effective farriery treatment of hypoflexion tendons (severe digital hyperextension) in a foal. Equine Vet Educ 11 (5) 256-259 VetMedResource.
- Kaneps A J & Smith B L (1998) Management of distal limb lameness in foals. Comp Cont Educ 20, 1060-1066 VetMedResource.
- Munroe G A & Chan C H (1996) Congenital flexural deformities of the foal. Equine Vet Educ 8 (2), 92-96 VetMedResource.
- Fackelman G E & Clodiu L (1972) Surgical correction of the digital hyperextension deformity in foals. Vet Med Small Anim Clin 67, 1116 PubMed.