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Environmental
Causes:
Four broad categories -
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Chemical agents
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Deficiencies
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Physical factor
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Infectious agents
1. Chemical agents:
a) Plant constituents:
Australian plants include:
hemlock or carrot fern (Cornium maeculata) – in calves, spinal
curvature, limb rotation, arthrogryposis, cleft palate and hair lips
Wild tobacco (Nicatiana spp) and pituri (Duboisia lapwoodi) –
in pigs, arthrogryposis
Horn apple (Datura spramonium) – in pigs causes arthrogryposis
b) Therapeutic substances:
Tetracycline, griseofulvin, parbendazole, corticosteriods
c) Trace elements:
Copper, manganese
d) Excess:
Oxygen, carbon dioxide, vitamins A and D
2. Deficiencies:
Usually nutritional
For example: Vitamins A, B, D
Iodine deficiency in pregnant animals can lead to congenital goitre
Lamb - congenital colloid goiter
3. Physical factors:
High environmental temperature – sufficient enough to raise core
body temperature even a few degrees above normal can lead to severe foetal
abnormalities especially if it occurs in early foetal development
irradiation
4. Infectious agents:
Akabane virus
Blue tongue
Bovine viral diarrhoea, mucosal disease and hairy shaker disease in
sheep (all the same virus)
Feline panleucopenia – can produce cerebellar hypoplasia
Infectious bovine rhinotracheitis
Akabane disease -
Occasionally occurs as an epidemic
Last epidemic – 1974. Many newborn calves and lambs affected
and animals died soon after birth.
4 types of abnormalities occur:
Polioencephalomyelitis
Mild non-suppurative encephalomyelitis
Arthrogryposis (image next slide)
Hydranencephaly – both cerebral hemispheres replaced by fluid
Sheep - Arthrogryposis due to Akabane infection
Further Reading:
Noden and de Lahunta (1984). Embryology of domestic animals. Williams
and Wilkins.
Lupold, HW, Dennis, SM and Huston, K (1972). Congenital defects of
cattle: nature, cause and effect. Adv. Vet. Sci. composed 16: 103-150.
Jubb, KV, Kennedy PC and Palmer, N (1993). Pathology of domestic animals.
Academic Press.
Seawright, AA (1982). Animal health in Australia, Vol 2, Chemical and
plant poisons, Aust. Gov. Pub. Serv., Canberra
Nicholas, FW and Harper, PAW (1996). The occurrence of schistosomus
reflexus in bovine dystokia. Aust. Vet. J. 73:22
McLennon, MW, Kelly, WR, Sutton, RH (1966). Eisenmenger complex in
two calves. Aust. Vet. J. 73:22
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