11.3.2: Scour in sheep

Question 1

Differentials for scour in neonates

Answer 1

Nutritional
* Incorrect mixing of milk replacer (if bottle fed)

Bacterial
* E. coli (watery mouth)
* Clostridium perfringens type B (lamb dysentery)
* Salmonella

Viral
* Rotavirus

Parasitic
* Cryptosporidium

Question 2

Differentials for scour in lambs

Answer 2

Nutritional
* Rumen acidosis (creep feeding)

Parasitic
* Coccidiosis
* Nematodirus
* Parasitic gastroenteritis (PGE)

Question 3

Differentials for scour in adults

Answer 3

Nutritional
* Rumen acidosis/lush pasture

Bacterial
* Salmonella
* (Johnes)

Question 4

Clinical signs of watery mouth and age of lambs affected

Answer 4

Lambs are infected at <4 days old
* Pyrexia
* Lethargy
* ± Scour
* High mortality rates
* “Watery mouth” - lambs hypersalivate
* “Rattle belly” - lambs get pot bely

Question 5

What factors affect the risk of watery mouth infection and how can this be prevented/controlled?

Answer 5

• Watery mouth is associated with poor hygiene and failure of passive transfer
• Good hygiene: clean dry bedding in pens, individual pens changed between ewes, hospital pens for sick animals
• Colostrum management: 50ml/kg colostrum ASAP (<6hrs) after birth, 200ml/kg in first 24hrs. For 5kg lamb = 250ml in 6hrs, 1L in 24hrs
• Check ewe nutrition and BCS (forage, metabolic profiling)

Question 6

Causative agent and clinical signs of lamb dysentery

Answer 6

Causative agent: Clostridium perfrigens Type B
* Sudden death in lambs
* May see blood-tinged diarrhoea
* Lambs appear dull/listless before death
* Affects young lambs (usually <3 weeks)

Question 7

True/false: Clostridia are gram +ve, anaerobic bacteria that are commensals of the GIT.

Answer 7

True
They are commensals in the GIT and ubiquitous in the environment

Question 8

How can you prevent lamb dysentery?

Answer 8

• Vaccination of ewes
• Vaccination of lambs from 2-3 weeks
• Check that the clostridial vaccine being used covers for the desired strain e.g. lamb dysentery = C. perfrigens Type B

Question 9

What time of year do we see coccidiosis?

Answer 9

Jan-May
* This is related to the seasonality of lambing rather than of the parasites

Question 10

Causative agent of coccidiosis in lambs

Answer 10

Coccidiosis = caused by Eimeria (protozoal parasite)
* Eimeria are host-specific (take care with oocyst counts)
* Only 2 are pathogenic in sheep: E. ovinoidalis, E. crandallis

Question 11

Which lambs are most at risk for coccidiosis?

Answer 11

• Lambs 3-12 weeks old, especially those born later in the lambing period
• Lambs born the the first half of lambing period are exposed to low level of challenge and develop immunity
• These early lambs multiply up the oocysts in the shed/field so the youngest lambs enter a high challenge environment and suffer clinical disease (scouring, dehydration) before they develop immunity

Question 12

Risk factors for coccidiosis

Answer 12

• Mixing age groups of lambs
• Moving young lambs to shed/pasture where older lambs were kept
• Intensively stocked systems
• Faecal contamination in/around feed/water troughs

Question 13

Pathogenesis and clinical signs of coccidiosis

Answer 13

• Damage to the gut lining
• Straining
• Abdominal pain
• Diarrhoea ± mucus and blood
• Dehydration
• Death (in young lambs exposed to high challenge)
• Affected animals show ill thrift and poor growth rates

Question 14

Control of coccidiosis

Answer 14

• Ensure adequate colostrum intake, maintain good hygiene, prevent faeco-oral transmission e.g. raise feed and water troughs or move frequently; have more feed and water troughs to reduce crowding
• Reducing stocking density

Question 15

What time of year do we see cryptosporidium in lambs?

Answer 15

Jan-May/June

Question 16

Which age of lambs are affected by cryptosporidium and what are the clinical signs?

Answer 16

Causative agent: Cryptosporidium parvum
* Disease in young lambs (usually <10 days old)

Clinical signs
* Diarrhoea
* Inappetence
* Abdominal pain
* Mild pyrexia
* Mild infections: reduced growth rates, general poor performance
* Mixed infections with E. coli/Nematodirus = severe clinical signs

Question 17

Diagnosis of Cryptosporidium parvum

Answer 17

• Faecal sample
• Post-mortem

Question 18

Transmission and control of Cryptosporidium parvum

Answer 18

• Faecal-oral transmission
• Oocysts persist in the environment and are resistant to many disinfectants -> this causes infection levels to build up over time
• ⚠️Zoonotic⚠️

Control
* Ensure adequate colostrum intake, maintain good hygiene, prevent faeco-oral transmission by raising feed and water troughs
* Avoid mixing age groups (older animals tend to transfer to younger ones
* Check that disinfectants used are effective against crypto