Difference between revisions of "Bones Developmental - Pathology"

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==Generalised==
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#REDIRECT[[:Category:Bones - Developmental Pathology]]
===Proportionate dwarfism===
 
*Miniature breeds
 
*Due to growth factor deficit
 
===Chondrodysplasia===
 
 
*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 [[Bones - normal#Bone development|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]]
 
 
 
===Osteopetrosis (Marble bone disease)===
 
 
 
*Occurs in sheep, dogs, cattle, horses
 
*Failure of resorption by osteoclasts -> failure of remodelling of [[Bones - normal#Bone organisation|cancellous bone]]
 
*Bones become thickened and dense but brittle
 
*Marrow cavites are full of unresorbed primary spongiosa
 
*Thickened intramembranous bones of skull -> altered shape of brain
 
*Associated with severe viral infections, e.g.  '''FeLV''', [[Bovine Viral Diarrhoea Virus|BVD]]
 
*Hereditary in Angus cattle
 
 
 
===Lysosomal storage disease===
 
 
 
*Excess accumulation of metabolites in lysosomes
 
*Affects mainly nervous system
 
*Also affects growth of cartilage
 
 
 
 
 
===Osteogenesis Imperfecta===
 
 
 
*Cause of fragile bones in humans, very rarely in animals
 
*Reported in Holstein and Charolais calves
 
*Poor mineralisation of bones and teeth
 
*Fractures are often present at birth
 
 
 
 
 
===Congenital hyperostosis of pigs===
 
[[Image:Hyperostosis.jpg|right|thumb|100px|<small><center>Hyperostosis (Image sourced from Bristol Biomed Image Archive with permission)</center></small>]]
 
 
 
*Rare, genetic
 
*Diaphysial dysplasia
 
*Excessive periosteal intramembranous bone, particularly in long bones
 
*Grossly:
 
**Greatly thickened long bones
 
**Tense, shiny skin, closely adherent to tissues below
 
*Born dead or die soon after birth
 
 
 
 
 
 
 
 
 
 
 
 
 
===Retention of elongated primary trabeculae===
 
 
 
*Happens due to impaired osteoclastic activity
 
*Primary trabeculae do not transform into secondary and tertiary
 
*Continue to elongate
 
*Form a dense band beneath growth plate - growth retardation lattice
 
*Dense spikules apparent on radiographs
 
*Can be caused by [[Paramyxoviridae#Canine Distemper Virus (CDV)|distemper virus]], [[Flaviviridae|bovine viral diarrhoea virus]]
 
 
 
==Localised==
 
 
 
*'''Hemimelia''' - abscence of one of limb bones
 
*'''Syndactylia''' - fusion of toes
 
*'''Polydactylia''' - increased number of digits
 
*'''Ectrodactylia''' - cleft in paw extending to metacarpus of dogs and cats
 
 
 
 
 
===Cervical Vertebral Stenotic Myelopathy (Wobblers)===
 
 
 
*Equine disease
 
*Narrowing of the vertebral canal due to malalignment or maldevelopment of the vertebrae
 
*Fast growing male TBs ranging from 8 months to 4 years
 
*Hind limb ataxia due to cord compression
 
 
 
 
 
===Angular limb deformity===
 
 
 
*Lateral deviation of distal portion of limb (valgus)
 
*Medial deviation of distal portion of limb (varus) - more rare
 
*Most common in foals
 
**Carpal joint
 
**Tarsal joint
 
**Fetlock joint
 
*Congenital or acquired
 
*Due to:
 
**Malpositioning in utero
 
**Excessive joint laxity
 
**[[Thyroid Gland - Pathology#Hypothyroidism|Hypothyroidism]]
 
**Trauma
 
**Overnutrition
 
**Defective endochondral ossification
 
**Poor conformation
 
**Disruption of blood supply to one side of bone
 
**Secondary to [[Bones Developmental - Pathology#Physitis|physitis in horses]]
 
*Usually resolves spontaneously in one to two weeks of life
 
*More severe cases exceding compensatory capabilities will persisist
 
*[[Bones - normal#Bone development|Cartilage development]] is affected
 
 
 
 
 
===Fibrous dysplasia===
 
 
 
*See [[Bones Hyperplastic and Neoplastic - Pathology#Fibrous dysplasia|Bones and Cartilage - hyperplastic and neoplastic]]
 
 
 
 
 
===Physitis===
 
 
 
*In horses
 
*Often associated with [[Bones Developmental - Pathology#Angular limb deformity|angular limb deformity]]
 
*Also called '''epiphysitis''' and '''physeal dysplasia'''
 
*Problem of [[Bones - normal#Bone development|endochondral ossification]]
 
*Two age groups
 
**Weanlings
 
**Yearlings in early training and two-year-olds
 
*May cause contracted tendons and flexural deformities
 
*Factors probably involved in its development:
 
**Genetically fast growth rate
 
**Large quantities of imbalanced, high energy feed
 
**Imbalanced weight-bearing on joints
 
**Excessive activity
 
**Growth spurts
 
*Histologically: (appearance similar to [[Bones Developmental - Pathology#Angular limb deformity|angular limb deformity]])
 
**Lateral aspect of radius
 
***Thickened metaphyseal part of physeal cartilage
 
***-> Delay or disturbance of endochondral ossification
 
***Compression
 
**Central part
 
***No obvious deformity
 
**Medial aspect
 
***Tension
 
***-> Transverse [[Bones Fractures - Pathology|fractures]] and repair
 
**Laxity of periarticular attachements in young foals allows [[Bones Developmental - Pathology#Angular limb deformity|angular limb deformity]]; not occuring in older foals and young horses
 
**(Sustained trauma produces similar lesions)
 
 
 
 
 
[http://www.omafra.gov.on.ca/english/livestock/horses/facts/info_congenital.htm#musculoskeletal Developmental abnormalities]
 
 
 
 
 
==Test yourself with the Bone and Cartilage Pathology Flashcards==
 
 
 
[[Bones_and_Cartilage_Flashcards_-_Pathology|Bones and Cartilage Flashcards]]
 
 
 
 
 
[[Category:Musculoskeletal System - Pathology]]
 

Latest revision as of 18:28, 27 February 2011