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.
1. Leipold HW, Morris LN. Syndactyly. In: Andrews EJ, Ward BC, Altman NH, eds. Spontaneous animal models of human disease. New York: Academic Press, 1979; 213–214.
2. Jezyk PF. Constitutional disorders of the skeleton in dogs and cats. In: Newton CD, Nunamaker DM, eds. Textbook of small animal orthopaedics. Philadelphia: Lippincott, 1985; 637–654.
3. Kozin SH. Current concepts review: upper-extremity congenital anomalies. J Bone Joint Surg Am 2003; 85: 1564–1576.
5. Towle HA, Blevins WE, Tuer LR, et al. Syndactyly in a litter of cats. J Small Anim Pract 2007; 48: 292–296.
6. Hanson RR. Congenital and inherited anomalies of the musculoskeletal system in multiple species. In: Aiello SE, Moses MA, eds. The Merck veterinary manual. 2013. Available at: www.merckmanuals.com. Accessed Jun 22, 2015.
7. Madgwick R, Forest V, Beglane F. Syndactyly in pigs: a review of previous research and the presentation of eight archaeological specimens. Int J Osteoarchaeol 2011; 23: 395–409.
8. Kapke P, Jorgensen HP, Rothschild MF. Swine research report—paper 14. A study of genetic diversity in a rare US pig breed—the Mulefoot pig. Available at: lib.dr.iastate.edu/swinereports_1996/14. Accessed May 15, 2014.
9. Scherf BD. Farm animal genetic resources. In: World Watch List for domestic animal diversity. 3rd ed. Rome: Food and Agriculture Organization of the United Nations, 2000;37–646.
13. Ross OB, Phillips PH, Bohstedt G, et al. Congenital malformations, syndactylism, talipes, and paralysis agitans of nutritional origin in swine. J Anim Sci 1945; 3: 406–414.
15. Agostinho FS, Rahal SC, Araujo FAP, et al. Gait analysis in clinically healthy sheep from three different age groups using a pressure-sensitive walkway. BMC Vet Res 2012; 8: 87.
16. Verdugo MR, Rahal SC, Agostinho FS, et al. Kinetic and temporospatial parameters in male and female cats walking over a pressure sensing walkway. BMC Vet Res 2013; 9: 129.
17. Meijer E, Bertholle CP, Oosterlinck M, et al. Pressure mat analysis of the longitudinal development of pig locomotion in growing pigs after weaning. BMC Vet Res 2014; 10: 37.
18. Meijer E, Oosterlinck M, Nes A, et al. Pressure mat analysis of naturally occurring lameness in young pigs after weaning. BMC Vet Res 2014; 10: 193.
19. Lascelles BD, Roe SC, Smith E, et al. Evaluation of a pressure walkway system for measurement of vertical limb forces in clinically normal dogs. Am J Vet Res 2006; 67: 277–282.
20. Karriker LA, Abell CE, Pairis-Garcia MD, et al. Validation of a lameness model in sows using physiological and mechanical measurements. J Anim Sci 2013; 91: 130–136.
21. Main DCJ, Clegg J, Spatz A, et al. Repeatability of a lameness scoring system for finishing pigs. Vet Rec 2000; 147: 574–576.
23. Light TR. Congenital anomalies: syndactyly, polydactyly, cleft hand. In: Peimer C, ed. Surgery of the hand and upper extremity. New York: McGraw-Hill, 1996;2111–2144.
24. Dao KD, Shin AY, Billings A, et al. Surgical treatment of congenital syndactyly of the hand. J Am Acad Orthop Surg 2004; 12: 39–48.
25. Bae DS. Release of simple syndactyly. In: Flynn JM, Wiesel SW, eds. Operative techniques in pediatric orthopaedics. Philadelphia: Lippincott Williams & Wilkins, 2011; 326–332.
27. Hart-Elcochk L, Leipold W, Baker R. Hereditary bovine syndactyly: diagnosis in bovine fetuses. Vet Pathol 1987; 24: 140–147.
28. Leipold HW, Schmidt GL, Steffen DJ, et al. Hereditary syndactyly in Angus cattle. J Vet Diagn Invest 1998; 10: 247–254.
30. Towle H, Friedlander K, Ko R, et al. Surgical treatment of simple syndactylism with secondary deep digital flexor tendon contracture in a Basset. Vet Comp Orthop Traumatol 2007; 20: 219–223.
32. Rodríguez-Alarcón CA, Beristain-Ruiz DM, Itzá MF, et al. Syndactyly and concurrent multiple pad agenesis in all four limbs with secondary deep digital flexor contracture in a puppy - a case report. Vet Arhiv 2014; 84: 319–329.
33. Carvalho VC, Nääs IA, Mollo Neto M, et al. Measurement of pig claw pressure distribution. Biosystems Eng 2009; 103: 357–363.