Chondrodysplasia

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  • Literally means “abnormal cartilage development”
  • Defective cartilage growth at the physis
  • Usually genetic cause
  • Occurs in cattle, dogs, sheep, pigs and cats
  • Leads to disproportionate dwarfism (contrast with miniature breeds)
    • Generally, growth is disproportionate because only the growth of bones which form from cartilage models is retarded – growth of other bones is normal (i.e. long bones shorter than normal)

In Dogs:

  • Localised forms occur in dogs (e.g. affecting skulls of Pekingese and Bulldogs or the limbs of Dachshunds and Bassett hounds)
  • Occasionally seen in immature Beagles, Poodles, Alaskan Malamutes, Scottish Deerounds and Norwegian Elkhounds

In Cattle:

  • Dexter cattle
    • Are heterozygous for incompletely dominant gene
    • When homozygous - lethal, producing 'bulldog calf'
      • A well recognised deformation in Dexter calves.
      • Related to defective cartilage matrix and abnormal ossification.
      • The calf is born with short and crooked limbs and the facial bones are short.
    • Usually aborted prior to seven month of pregnancy
    • Also occurs in Holstein, Jerseys and Charolais
    • Grossly:
      • Limbs and vertebral column are short
      • Domed cranium
      • Protruding tongue
      • Absent hard palate
      • Large umbilical hernia with eventrated abdominal organs
    • Histologically:
      • Proliferative and hypertrophic zones in the physes are irregularly separated by fibrovascular tissue
      • Chondrocytes are not properly arranged
      • Irregular ossification and mineralisation
  • Telemark type
    • Cattle of Norwegian origin
    • Also seen in Jersey cows
    • Calves born alive, unable to stand and die soon after birth
    • Grossly:
      • Domed cranium
      • Brachygnatic face
      • Protruding tongue
      • Cleft palate
      • Short neck and limbs
  • Brachycephalic 'Snorter' type
    • Hereford and Aberdeen Angus
    • Show nasal dyspnoea and chronic rumenal tympany
    • Grossly:
      • Short, broad head
      • Prominent, laterally displaced eyes
      • Short and compressed vertebral column
      • Distal long bones shorter than proximal
    • Histologically:
    • Physes appear normal
    • Pallisading chondrocytes fewer in number
    • Less hypertrophy

In Sheep:

  • Ancon type
    • Short limbs due to premature closure of growth plates
    • Now rare
  • Spider lamb
    • Hereditary (autosomal recessive) in Suffolk and Hampshire breeds in North America
    • Long, thin, angular limbs
    • May be born alive or dead, aborted or develop symptoms within a month of birth
    • Grossly:
      • Fine bones, poor musculature, small heads, scoliosis
    • Histologically:

In Pigs:

  • Occurs in Danish Landrace
  • Autosomal recesive inheritance
  • Dwarfs with short legs, forelegs shorter than hind legs
  • Abnormal movement is noticable at weaning
  • Sequel is arthrosis