Congenital bilateral aplasia of the metacarpophalangeal joints in a foal

Abstract

A 2-day-old Warmblood filly was presented for examination of an angular limb deformity of the left front limb and an upright conformation of both metacarpophalangeal joints. Radiological examination revealed bilateral absence of the metacarpophalangeal joint space with fusion of the third metacarpal bone and first phalanx (synostosis). No treatment was undertaken. The filly was readmitted to the clinic 10 weeks later for bilateral front limb lameness. On radiological examination, the synostosis of the front metacarpophalangeal joints was still present. Physitis of the distal growth plate of the right third metacarpal bone and proximal growth plate of the right proximal phalanx, and an avulsion fracture of the palmaromedial and proximal aspect of the left middle phalanx, with a cystic like lesion on the medial aspect of distal first phalanx and proximal middle phalanx were diagnosed. Given the poor prognosis, the foal was subjected to euthanasia. Post mortem examination confirmed the absence of the metacarpophalangeal joint space with a trabecular bony union between the third metacarpal bone and the first phalanx. A rudimentary joint capsule was present at the level of the absent joints as well as a small zone of articular cartilage, which invaginated over a short distance into the dorsal trabecular bone on the right front limb. On the medial aspect of the left proximal interphalangeal joint, a focal defect of articular cartilage with exposure of subchondral bone was observed. This is the first case report of a foal born with congenital aplasia of both metacarpophalangeal joints. Congenital malformations should be considered as differential diagnosis in lame foals or foals born with angular or flexural limb deformities

Bilateral patellar aplasia in a foal

“…These abnormalities are thought to be hereditary in nature, however the exact aetiology of the defects is unknown (Engelbert et al, 1993;Hermans et al, 1987;Talbot & Singer, 2009). Environmental or genetic pathologies that occur during embryonic development can affect chondrogenesis or skeletogenesis, resulting in congenital skeletal deformities (Bertone & Aanes, 1984;DeBowes & Leipold, 1984;Huston et al, 1977;Jordana et al, 2016;Smith et al, 1986;Trumble 2005). Previous reports have hypothesised that abnormal patellar ossification in horses could be due to disruption of vascular perfusion, repetitive vascular microtrauma, dysregulation of various developmental or cellular processes, or anomalous chondrogenesis and bone formation (Jordana et al, 2016;Smith et al, 1986;Van der Zaag et al, 2016;Vanlerberghe et al, 2018).…”

“…Environmental or genetic pathologies that occur during embryonic development can affect chondrogenesis or skeletogenesis, resulting in congenital skeletal deformities (Bertone & Aanes, 1984;DeBowes & Leipold, 1984;Huston et al, 1977;Jordana et al, 2016;Smith et al, 1986;Trumble 2005). Previous reports have hypothesised that abnormal patellar ossification in horses could be due to disruption of vascular perfusion, repetitive vascular microtrauma, dysregulation of various developmental or cellular processes, or anomalous chondrogenesis and bone formation (Jordana et al, 2016;Smith et al, 1986;Van der Zaag et al, 2016;Vanlerberghe et al, 2018). The rarity of equine patellar aplasia makes it difficult to determine if this is an inherited or acquired congenital abnormality in the singular case reported here.…”

“…Equine congenital malformations that affect the limbs are very rare, representing only 1.6% of congenital abnormalities (Bertone & Aanes, 1984; Jordana et al., 2016 ; Schenzel et al., 2020 ; Smith et al., 1986 ). Hypoplasia or aplasia have been previously described to affect the navicular bone, phalangeal joint and metacarpophalangeal joint (Bertone & Aanes, 1984; Jordana et al., 2016 ; Schenzel et al., 2020 ; Smith et al., 1986 ). Congenital patellar abnormalities primarily affect miniature horses and are rarely reported in foals.…”

“…Polydactyly occurs most frequently and typically affects the forelimbs (Smith et al., 1986 ). Absent, aplastic, or dysplastic bones are rare, and only cases affecting the phalanges and/or distal sesamoids have been reported (Bertone & Aanes, 1984; Jordana et al., 2016 ; Schenzel et al., 2020 ; Smith et al., 1986 ). Congenital patellar aplasia or hypoplasia is a rare disorder in humans that usually does not cause significant knee dysfunction and is often accompanied by other congenital abnormalities (Jerome et al., 2008 ; Jerome et al., 2009 ; Sferopoulos, 2018 ).…”

A case of polydactyly in a foal

“…Inny przykład cech atawistycznych stanowią w pełni wykształcone kości łokciowa i strzałkowa rozpoznane u kuca (9) oraz dwudzielna kość kopytowa i trzeszczka kopytowa, wykryte u dorosłego konia w trakcie badania w związku z nagłym wystąpieniem kulawizny po wizycie podkuwacza (5). Opisana została również wrodzona aplazja dotycząca stawu pęcinowego (6).…”