The term splay leg indicates a deformation of the limbs (front and rear) that are maintained in permanent adduction. It is a purely descriptive clinical term that does not indicate the aetiology of the condition. The condition can affect any one of the four limbs, more limbs, or all four of them, with variable severity (Figs. 1 and 2). In more severe cases the front legs are kept extended in caudal direction, against the body (Fig. 3). The ability of the affected animals to move is seriously impeded; the animals are generally unable to stand and move by crawling for short stretches, crawling on the sternum. Notwithstanding the deformation, affected subjects grow normally. Common complications are perineal dermatitis, resulting from contamination with faeces and urine, and limb skin ulcerations at the contact points with the floor.
Hind limb lesions associated with splay leg consist of dislocation or subluxation of the hip joint, shallow acetabulum, thickening of the joint capsule of the hip and knee, lateral patellar dislocation, valgus deformity and mild bowing of the tibia. Muscle injuries are minor and no neurological injuries are present.
AETIOLOGY
Genetic factors are believed to play an important role in the development of the disease. A study has provided strong evidence that in the Dwarf Lop rabbit the condition is linked to an autosomal recessive gene. However, environmental factors cannot be excluded in the development of the condition. It has been experimentally demonstrated that the presence of a slippery floor substrate during the early stages of development is related to the appearance of splay leg in young rabbits. The presence of a non-slippery substrate, which provides traction to the limbs, reduces instead significantly the incidence of splay leg. Further studies are needed to definitively clarify the aetiology of this condition.
In adult rabbits the onset of a permanent limb adduction may have different causes: neurological diseases (spinal fractures, spondylosis), systemic conditions that cause generalized weakness, orthopaedic injuries, osteoarthritis, muscle atrophy in elderly and sedentary subjects.
DIAGNOSIS
In young subjects the diagnosis of splay leg is mainly clinical. X-rays (Fig. 4) may be useful to rule out the presence of any bone injuries.
TREATMENT
If the intervention is within two months of age the limb malformation may be successfully corrected with the use of a brace that must be maintained until consolidation of the limbs in their normal position. A marked improvement can be achieved also in three-month old rabbits, but in this case the recovery times are much longer. Treated rabbits should be kept on non-abrasive substrates. To prevent secondary dermatitis, attention must be paid to environmental hygiene and the perineal area must be kept dry. Subjects are able to eat spontaneously.
Braces or strappings must be customised according to the degree of malformation and the number of affected limbs. Importantly, braces should be comfortable and not block the circulation. They should be checked more times a day and replaced to accompany the growth of the animal or when dirty. They should normally be replaced every 4-5 days. Suitable materials for braces are adhesive bandages, paper tape, zinc oxide tape (the latter is not to be applied directly to the bare skin). Braces are applied so as to bring the limbs together in a physiological position. For the hind limbs, the legs are joined together first, and then the feet (Figs. 5-8). In the forelimbs, the arms are brought together just above the region of the carpus. In subjects over two months of age, in which the adduction of the limbs is more difficult, it is possible to make the correction progressively. In some cases it may be useful to keep the feet in flection before strapping, in order to avoid maintaining the limbs extended backwards (Fig 9). In more severely compromised subjects brace application requires a few days of adaptation, but the animals should then be able to maintain a normal posture (Fig. 10) and to move in leaps.
Suggested reading
- Owiny, James R.; Vandewoude, Sue; Painter, J. Todd; Norrdin, Robert W.; Veeramachaneni, D. N. Rao. Hip Dysplasia in Rabbits: Association with Nest Box Flooring. Comp Med. 2001 February; 51(1):85-8.
- G M Arendar, R A MILCH. Splay-leg--a recessively inherited form of femoral neck anteversion, femoral shaft torsion and subluxation of the hip in the laboratory lop rabbit: its possible relationship to factors involved in so-called "congenital dislocation" of the hip. Journals: Clin Orthop Relat Res. 1966 Jan-Feb; 44(0):221-9.