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Created page with "*Literally means “abnormal cartilage development” *Defective cartilage growth at the physis *Usually genetic cause *Occurs in cattle, dogs, sheep, pigs and cats *Leads to '''..."
*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)
<u>In Dogs:</u>
*'''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
<u>In Cattle:</u>
*'''Dexter cattle'''
**Are heterozygous for incompletely dominant gene
**When homozygous - lethal, producing 'buldog calf'
**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 - Anatomy & Physiology|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 - Anatomy & Physiology|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
<u>In Sheep:</u>
*'''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:
***Abnormal centres of [[Bone & Cartilage Development - Anatomy & Physiology|endochondral ossification]]
***Nodular cartilage hypertrophy
<u>In Pigs:</u>
*Occurs in Danish Landrace
*Autosomal recesive inheritance
*Dwarfs with short legs, forelegs shorter than hind legs
*Abnormal movement is noticable at weaning
*Sequel is [[Joints Degenerative - Pathology#Degenerative joint disease (DJD)|arthrosis]]
[[Category:Bones - Developmental Pathology]]
*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)
<u>In Dogs:</u>
*'''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
<u>In Cattle:</u>
*'''Dexter cattle'''
**Are heterozygous for incompletely dominant gene
**When homozygous - lethal, producing 'buldog calf'
**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 - Anatomy & Physiology|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 - Anatomy & Physiology|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
<u>In Sheep:</u>
*'''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:
***Abnormal centres of [[Bone & Cartilage Development - Anatomy & Physiology|endochondral ossification]]
***Nodular cartilage hypertrophy
<u>In Pigs:</u>
*Occurs in Danish Landrace
*Autosomal recesive inheritance
*Dwarfs with short legs, forelegs shorter than hind legs
*Abnormal movement is noticable at weaning
*Sequel is [[Joints Degenerative - Pathology#Degenerative joint disease (DJD)|arthrosis]]
[[Category:Bones - Developmental Pathology]]