Unilateral phalangeal dysgenesis and navicular bone agenesis in a foal

Fusion of the distal sesamoid and distal phalanx in a yearling colt

“…In this 15‐month‐old colt, the failure of the distal sesamoid is not consistent with the hypothesis of growth retardation. For this reason the present case is different from others in the literature (Taylor and Morris 1983, Bertone and Anes 1984, Smith and others 1986, Modransky and others 1987, Fischer 1999).…”

“…ANATOMICAL defects of the digits are uncommon in horses; polydactyly is the most frequently reported anomaly (Theile 1958, Evans and others 1965, Huston and others 1977), and agenesia or hypoplasia of the distal sesamoid is rare (Taylor and Morris 1983, Bertone and Anes 1984, Smith and others 1986, Modransky and others 1987, Fischer 1999). However, congenital appendicular skeletal disorders should be considered as a differential diagnosis of cases of severe lameness in foals.…”

Bilateral patellar aplasia in a foal

“…Foals affected with patellar abnormalities present with the inability to extend the stifles, as the quadriceps muscle acts as a flexor instead of an extensor of the joint; therefore, the foal assumes a squatting or crouched position when forced to stand (Finocchio & Guffy, 1970;Talbot & Singer, 2009;Trumble 2005;Van Pelt et al, 1971). Diagnosis of skeletal congenital abnormalities can be challenging, as many defects present with similar clinical appearances and require diagnostic imaging to help determine a definitive diagnosis (Modransky et al, 1987;Riley et al, 1990). When patellar abnormalities are suspected, lateromedial, caudoproximalcraniodistal oblique and craniodistal-cranioproximal (skyline) oblique radiographic views are commonly used to assess the stifle joint and position of the patella (O'meara & Lischer, 2009).…”

Unilateral congenital phalangeal hypoplasia in a colt

“…There is an absence of the distal interphalangeal joint in the right hindfoot and fusion between a rudimentary navicular bone and the plantarodistal aspect of P2, with their medullary bone being continuous. (Taylor and Morris 1983;Bertone and Aanes 1984;Smith et al 1986;Modransky et al 1987), it would appear that common features of the condition include: unilateral limb involvement with a contracted hoof; varying degrees of lameness of the affected limb; the absence of other congenital abnormalities (unlike the condition described for cattle where bilateral absence of the patella, shortening of the tibia and other abnormalities may also be present), although one report cites the concurrent presentation of 'contracted tendons' (Mitchell and Parkes 1974). Phalangeal hypoplasia has been encountered in a variety of different breeds (mule, Arabian, Appaloosa, Thoroughbred and Morgan) and equal numbers of colts and fillies have been represented.…”

“…In one study, phalangeal abnormalities made up only 1.6% of equine congenital defects collated over a 13 year period (Crowe and Swerczek 1985). Polydactyly (more digits than normally present for a given species), appears to be the most common presentation (Stanek and Hantak 1986) but reports on adactyly (Leipold and Macdonald 1971) and phalangeal hypoplasia of various degrees (with regard to number and extent of phalangeal bones affected) also exist (Mitchell and Parkes 1974;Taylor and Morris 1983;Bertone and Aanes 1984;Smith 1986;Modransky et al 1987). This paper describes the case history, clinical, radiographic and post mortem (gross and microscopic) findings of a foal with unilateral congenital phalangeal hypoplasia in a hindlimb.…”