Calf diarrhoea Flashcards
Calf diarrhoea affects calves of what age?
In the first 21 days of life
What are the routes of transmission of pathogens causing calf diarrhoea?
Faecal-oral, environmental transmission (age mixing), carrier animals, fomites
What are the sources of infection of calf diarrhoea?
Affected animals, asymptomatic carriers (adults and sub-acute calves), environment
Describe the factors which can predispose calves to diarrhoea.
- Exposure to ++ infectious agents
- Failure of immunological defence mechanisms
- Poor colostrum intake
- Inadequate nutrition
- Poor management = stress
Name the pathogens associated with Calf Diarrhoea.
Rotavirus, Coronavirus, Cryptosporidium, Enterotoxogenic E. coli, Salmonella
Which viral pathogen is associated with scours in calves and winter dysentery in adults? They also cause respiratory disease in cattle and humans.
Coronavirus
Newbury agent is which type of virus?
Bovine Calicivirus
A Torovirus which is considered zoonotic…
Bredavirus
Which Cryptosporidium species is associated with neonatal diarrhoea?
Parvum
Which type of stain can be used to identify cryptosporidium species?
ZN - shows pink crypto organisms
Describe the life cycle of Cryptosporidium species.
Water containing oocysts is ingested by the host, oocysts encyst in the small intestine, asexual reproduction produces oocysts in the SI, oocysts are passed in the faeces where the sporulate (infective)
Which species of Salmonella are important causes of calf diarrhoea?
Dublin, typhimurium, newport..
Describe the morphology of E. coli ..
Gram -ve rod
ETEC causes disease in which aged calves?
Less than 5 days old
What clinical signs are associated with ETEC related disease in calves?
Acute, rapid dehydration, diarrhoea and death within 24-48 hours
What virulence factors are used by ETEC?
Adhesin pili attach bacteria to host, enterotoxins cause disease.
ETEC heat stable Enterotoxin - describe.
STa found in calves, causes a rise in c-GMP reduces fluid absorption.
ETEC heat-labile enterotoxin
LT - inhibits Na+(Cl- and H2O) absorption in villus cells and stimulates Na+ secretion in crypt cells - remember secretion is also regulated by calmodulin
Pathogenesis of ETEC?
Penetrates intestinal mucosa and enterotoxin causes secretion and reduced absorption of Na+, Cl- and H2O (increased osmotic gradient), profuse liquid faeces, rapid and severe dehydration, shock, high mortality.
Which other E. coli types are associated with calf diarrhoea?
Attaching and effacing, enteropathogenic, verocytotoxogenic
Which pathogens causing calf diarrhoea are associated with a) 0-6 days calves and b) 6+ days calves?
a) ETEC
b) Rotavirus, coronavirus, cryptosporidium
What is the pathophysiological mechanism of calf diarrhoea?
Hypersecretion - enterotoxins (diarrhoea)
Malabsorption - due to villous damage, decreased lactase activity, partial digestion – fermentation (acid production) - metabolic acidosis
Which pathogens cause hypersecretion diarrhoea?
ETEC, cholera
Which pathogens cause malabsorption diarrhoea?
Viruses, crypto
