Vitamin A
VITAMIN A (RETINOL, DEHYDRORETINOL)–Anti-infection vitamin
Sources
- Green plants; fish liver oils
- Carotene & Xanthene is converted to vitamin A in intestine
Storage
- Liver (Kupffer cells) as RETINOL
- adipose tissues
- Blood as lipoprotein
Deficiency of vitamin A
- Insufficient supply in ration
- Chronic diseases of intestine
- Liver diseases
- Poisoning with chlorinated naphthalene interferes with conversion of carotenes
- Increased phosphorous intake causes decreased vitamin A storage
Functions
- Bone growth
- Maintenance of epithelial surfaces
- Night vision
Respiratory system
- Ciliated columnar epithelium is transformed to stratified squamous epithelium
Reproductive tract
- Sterility in bulls
- Abortions
- Retained placenta
- Separation of maternal & foetal membranes
Urinary system
- Transitional epithelium is converted to stratified squamous epithelium and may lead to formation of urinary calculi
Eyes – Xeropthalmia
- No mucus secreting cells
- Keratinisation of corneal and scleral membrane
PATHOLOGY
Night blindnes s (Nyctalopia)
REVERSAL
Lesions in epithelial tissues
In gastro intestinal tract, respiratory tract, eye, skin, urogenital tract the epithelium is converted to keratinised, stratified squamous epithelium
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Skin- Acanthosis; Rough, dry coat, bran like scales (Pityriasis) Horses- Cracks in hooves
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Glands – Squamous metaplasia leading to obstruction and reduced digestion
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Lips and tongue – Plaque formation
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Bile duct and gall bladder – Cystic dilatation and pappilomatosis
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Renal tubules –Hyperplasia leading to fibrosis
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Male and female genitalia - Squamous metaplasia
Hyperkeratosis
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Clinical signs
- Lacrymation, anorexia, emasciation
- Dry, rough , hairless, wrinkled skin
- Fissures on skin
- Stomatitis
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Histopathology
- Hyperkeratosis of stratified squamous epithelium
- Metaplasia of ciliated columnar epithelium
Effect on bone growth
- Retarded bone growth in young animals
- Interference in growth of epiphyseal bone
- Capillaries do not invade cartilage
- No osteoblastic activity
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Calves
- No growth of skull
- Brain grows causing herniation into foramen
- Paralysis of skeletal muscles
- Blindness ( pressure on optic nerve)
- Encephalopathy
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Birds
- Defective bone growth
- Hydrocephalous causes increased cerebrospinal fluid pressure
Nutritional roup in poultry
- 1200-1600 1.U/kg of vitamin A included in ration of laying & breeders
- 600 1.U in ration of chicks
Clinical signs
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Adults
- Emasciation, weakness, ruffled feathers
- Decreased egg production
- Decreased hatchability
- Increased embroyonic malformations & mortality
- Caseous material in eyes
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Chicks
- Chronic – 3 wks and more age
- Decreased growth; poor feather development
- Caseous material in eyes; nostrils
- Nasal discharge; soiled feathers; paleness
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- Upper alimentary tract- pharynx, oesophagus
- Plaque like or cheesy membrane
- Small white nodules
- Gout
- Keratinisation of epithelium of ducts of glands
- Metaplasia to stratified squamous epithelium
- Occlusion of glandular ducts
Congenital anomalies
- Dermoids in eyes of calves
- Anoptholmos / Micropthalmos
- Anasarca
- Cleft palate
- Malformed limbs
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Last modified: Thursday, 22 March 2012, 8:12 AM