In dogs, radial agenesis usually begins to manifest at around day 23 - 35 of gestation. Both the radius and ulna can be affected and affected limb(s) are usually shortened with a varus deformity and are not functional or gaiting.
If all or part of the middle bones of a limb are absent, with the proximal and distal portions being present, the hemimelia is called intercalary. Preaxial longitudinal intercalary radial hemimelia is the most common type of hemimelia in dogs and may occur unilateral or bilaterally.
There may be complete or partial agenesis of either one or both radii with a compensatory increase in the diameter of the ulna. Congenital, bilateral, terminal anterior hemimelia in two families of Chihuahua dogs has been reported.
Affected dogs usually present at birth with unilateral or bilateral forelimb lameness and deformity.
Radiography and CT imaging are usually diagnostic, showing loss or absence of normal distal radial development and deformity of ulna and ulnocarpal joint.
Depending on the severity of the defect and client compliance, surgical correction can be attempted to improve limb function and mitigate the inevitable progression of osteoarthritis in the elbow and carpus.
Numerous osteotomy and stabilization techniques have been employed, including ulnocarpal arthrodesis, the use of external coaptation, linear external fixators, bone plates and screws and circular external fixators.
- Veterinary Research Institute
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