Syndactyly is a congenital anomaly that may compromise the hoof, skin, fibrous tissue, or bone, depending on the affected species.1–6 The defect has been described in humans3 and cattle4,6 and, less frequently, in sheep,1 dogs,2 cats,2,5 and pigs.7 In cloven-hoofed animals, the condition is also known as mulefoot because affected animals have fused or uncloven hooves that resemble the feet of a mule.4,7 The condition may occur as a sporadic malformation with no previous family history of the disorder, or it may occur as a genetic disorder.1,2,4
In swine, the Mulefoot breed is characterized by an uncloven hoof, although this breed is in a critical state according to the World Watch List for Domestic Animal Diversity.8,9 Few reports of the condition in other swine breeds exist,10,11 although the condition may persist in an entire population or breeding group.7 A single dominant gene has been linked to this condition in pigs,12 and researchers have induced congenital malformations of nutritional origin, including syndactylia, paralysis agitans, and talipes,13 which suggests that the condition may have diverse manifestations.7
Partial or complete fusion of the digits may occur in 1 or more limbs.6 However, dissection records, which indicate that the forelimbs are the most affected region, as well as results of radiography suggest that such fusion in pigs may have great diversity.7,10,14 Furthermore, there is controversy about the influence of syndactyly on locomotion. Some investigators have reported that affected animals tend to have fewer locomotion-associated problems, whereas other investigators have reported a restricted gait.7
Use of a pressure-sensing walkway as an objective method for gait analysis has facilitated studies15–18 of animal locomotion. The advantages of this method include evaluation of consecutive and simultaneous footfalls to reduce the labor and time required to complete data collection.17,19 These advantages are especially important for animals that may be problematic to handle, such as pigs.17,18,20
Syndactyly apparently is an uncommon problem in pigs that may induce health problems, presumably as a result of impaired gait; it may also pose a welfare issue. Therefore, the purpose of the study reported here was to characterize a population of pigs with naturally occurring syndactyly by use of plain radiographs and CT images and to evaluate kinetic and temporospatial variables by use of a pressure-sensing walkway. The main hypothesis was that syndactyly would not cause kinetic alterations or affect temporospatial variables.
This manuscript represents a portion of a dissertation submitted by Dr. Justolin to the Universidade Estadual Paulista (UNESP) School of Veterinary Medicine and Animal Science as partial fulfillment of the requirements for a Master of Science degree.
Supported in part by FAPESP (The State of São Paulo Research Foundation, No. 2009/18299-7) and CNPq (National Council for Scientific and Technological Development [No. 300710/2013-5]).
Peak vertical force
Digital X-ray system, GE Health DR-F, Rio de Janeiro, Brazil.
Spiral scanner, Shimadzu SCT-7800CT, Kyoto, Japan.
Voxer 3D 6.3, Barco, Kortrijk, Belgium.
Walkway high resolution HRV4, Tekscan Inc, South Boston, Mass.
Walkway software, version 7.0, Tekscan Inc, South Boston, Mass.
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