Calf Scour Flashcards

1
Q

Name the infectious agents which cause scour in calves

A

Salmonella (dublin & typhimurium), E. coli (ETEC), Cryptosporidium, Coccidiosis, Rotavirus, Coronavirus

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2
Q

Describe the pathogenesis of ETEC

A

Calves - age

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3
Q

Why is E. coli scour not seen in calves >5d old?

A

Abomasum becomes sufficently acidic to kill E. coli before they reach the SI and cause disease

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4
Q

What are the clinical signs of ETEC scour?

A
Profuse, foul smelling d+
Yellow
\+/- blood in scour
\+/- pyrexia
Wet mouth
Distended, watery abdomen
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5
Q

Describe the pathogenesis of Salmonella

A

Age

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6
Q

What are the clinical signs of Salmonella scour?

A
\+/- blood in scour
Pyrexia
Septicaemia
Vascular necrosis
Herd level - adult scour, abortion
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7
Q

Describe the pathogenesis of rotavirus/coronavirus

A

Age 5-21d - peaks at 10d then immune after 21d

  1. Invades enterocytes
  2. Replicates within then ruptures cells causing release of enterotoxin
  3. Villi shrink = decreased absorptive SA
  4. Hyperplasia of crypts in response to loss of villi
  5. Excess nutrients in lumen = osmotic d+
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8
Q

What are the clinical signs of rotavirus/coronavirus scour?

A
Profuse d+
White scour
Quickly become dehydrated
*can be confused with nutiritonal scour
Coronavirus - winter dysentery and respiratory disease in adults
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9
Q

Describe the pathogenesis of Crypto

A

Calves - age 1-3 wks, lambs - age 2-20d

Causes villous atrophy and crypt hyperplasia

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10
Q

What are the clinical signs of crypto?

A

Profuse watery d+
Quickly become dehydrated
Less severe systemic signs

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11
Q

Describe the pathogenesis of cocci

A

Age 3 wks - 3 months
Causes rupture of enterocytes
Malabsorption and osmotic d+

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12
Q

What are the clinical signs of cocci scour?

A

Black/bloody scour
Abdominal pain
Tenesmus
Walk with tail up

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13
Q

How is the cause of scour diagnosed?

A

CS
Calf-side ELISA - viruses, E. coli, crypto
PM

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14
Q

How is scour treated?

A

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)

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15
Q

Describe the lifecycle of crypto/cocci

A
  1. Host ingests oocyst
  2. Sporozoites hatch in SI and burrow into mucosa
  3. Form a trophozoite in extracytoplasmic vacuole
  4. Reproduce asexually to form 8 merozoites
  5. Merozoites hatch, enter other cells and reproduce asexually to form gametes
  6. Gametes fuse and lay down a cyst wall to become an oocyst
  7. Thin walled oocysts lyse and cause autoimmunity
  8. Thick walled oocysts excreted in faeces and are infective
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16
Q

What are the consequences of scour?

A

Decreased organ perfusion and azotaemia
Electrolyte loss
Metabolic acidosis

17
Q

How does scour cause a metabolic acidosis?

A

Bicarb lost in lumen means acid in bood can’t be neutralised and lactic acid increases due to shock
CHO can’t be digested so D-lactate increases which casues CS
To counteract this, the body exchanges H+ for luminal K+ which causes hyperkalaemia, cardiac arrhythmia and death

18
Q

Describe the fluid therapy regimen for animals with metabolic acidosis

A

9% dehydrated + mod/severe acidosis - IVT + bicarb

Mild acidosis = lactated/acetate fluid
Moderate = lactated/acetate + 15g bicarb
Severe = lactated/acetate + 35g bicarb

Spike with glucose for E
if unsure whether acidotic DO NOT give bicarb