Calf Scour Flashcards
Name the infectious agents which cause scour in calves
Salmonella (dublin & typhimurium), E. coli (ETEC), Cryptosporidium, Coccidiosis, Rotavirus, Coronavirus
Describe the pathogenesis of ETEC
Calves - age
Why is E. coli scour not seen in calves >5d old?
Abomasum becomes sufficently acidic to kill E. coli before they reach the SI and cause disease
What are the clinical signs of ETEC scour?
Profuse, foul smelling d+ Yellow \+/- blood in scour \+/- pyrexia Wet mouth Distended, watery abdomen
Describe the pathogenesis of Salmonella
Age
What are the clinical signs of Salmonella scour?
\+/- blood in scour Pyrexia Septicaemia Vascular necrosis Herd level - adult scour, abortion
Describe the pathogenesis of rotavirus/coronavirus
Age 5-21d - peaks at 10d then immune after 21d
- Invades enterocytes
- Replicates within then ruptures cells causing release of enterotoxin
- Villi shrink = decreased absorptive SA
- Hyperplasia of crypts in response to loss of villi
- Excess nutrients in lumen = osmotic d+
What are the clinical signs of rotavirus/coronavirus scour?
Profuse d+ White scour Quickly become dehydrated *can be confused with nutiritonal scour Coronavirus - winter dysentery and respiratory disease in adults
Describe the pathogenesis of Crypto
Calves - age 1-3 wks, lambs - age 2-20d
Causes villous atrophy and crypt hyperplasia
What are the clinical signs of crypto?
Profuse watery d+
Quickly become dehydrated
Less severe systemic signs
Describe the pathogenesis of cocci
Age 3 wks - 3 months
Causes rupture of enterocytes
Malabsorption and osmotic d+
What are the clinical signs of cocci scour?
Black/bloody scour
Abdominal pain
Tenesmus
Walk with tail up
How is the cause of scour diagnosed?
CS
Calf-side ELISA - viruses, E. coli, crypto
PM
How is scour treated?
Ab - systemically unwell or mucous/blood in d+
NSAID - for analgesia and to reduce inflammation
Halocur (Halofuginone) - reduce shedding of crypto
Cocci tx - Decoquinate (coccidiostat), Diclazuril (tx and px in lambs, control in calves), Toltrazunil (px CS and reduces shedding)
Describe the lifecycle of crypto/cocci
- Host ingests oocyst
- Sporozoites hatch in SI and burrow into mucosa
- Form a trophozoite in extracytoplasmic vacuole
- Reproduce asexually to form 8 merozoites
- Merozoites hatch, enter other cells and reproduce asexually to form gametes
- Gametes fuse and lay down a cyst wall to become an oocyst
- Thin walled oocysts lyse and cause autoimmunity
- Thick walled oocysts excreted in faeces and are infective