Farm animal diarrhoea

Question 1

3 factors that combine to cause calf diarrhoea

Answer 1

pathogens, environment and management, calf factors (immune status, stress)

Question 2

Pathogens causing calf diarrhoea - 7

Answer 2

• E.coli
• Rotavirus
• Coronavirus
• Cryptosporidium
• Salmonella
• Mixed infections
• Coccidiosis

Question 3

Significance of E.coli grown from faecal culture

Answer 3

Insignificant - all faecal cultures grow this. It is important to determine whether it is an enterotoxigenic type or not.- requires 2 factors

Question 4

2 factors for ETEC

Answer 4

Adhesive fimbriae and enterotoxin (carried on plasmids)

Question 5

3 types of E.coli infection

Answer 5

• Extraintestinal (colisepticaemia)
• Enteric (special strains, ETEC)
• Public health (rare, special strains, STEC)

Question 6

Signs of ETEC - calves/piglets/lambs

Answer 6

Neonatal enteritis (1-3 weeks old) - seen when <5days
More common in young animals with poor colostrum intake
Diarrhoea (stunting of villi)
Often in conjunction with rotavirus

Question 7

What are K88 and K99?

Answer 7

Types of fimbriae (cattle and pig respectively) that are enterotoxigenic. Also known as colonisation factors. Now called F4 and F5.

Question 8

Structure of labile toxin (LT)

Answer 8

5 B subunits, 1 A subunit (A1 or A2)
Similar to cholera toxin
Attaches to brush border of SI cells.
LT causes a Gs subunit to malfunction causing increases in cAMP level, activation of Cl- channel, Na+ and H2O loss from tissue into lumen –>secretory diarrhoea. Metabolic acidosis, dehydration and electrolyte loss are sometimes fatal.

Question 9

Effect of ST

Answer 9

Mechanism less well understood - types types STa and STb. STa raises intracellular GC (short-lived toxin, not immunogenic). STb - unknown action, non-immunogenic, difference aa sequence, porcine ETEC only.

Question 10

How do you diagnose ETEC?

Answer 10

Show both toxin (or gene) and fimbriae (or gene)

Question 11

Define STEC

Answer 11

Shiga-like toxin producing E.coli. Toxins are ST-1 and ST-2. Some diarrhoea and haemorrhagic colitis in calves. Previously called EHEC (enterohaemorrhagic)

Question 12

Public health significance of STEC

Answer 12

Carriage by calves - beef animals
Contamination of beef - cooked foods
Very low does (10CFU) infects humans (heamorrhagic colitis and haemolytic uraemic syndrome causes renal failure)

Question 13

How does STEC cause human disease?

Answer 13

Attaching and effacing lesion in gut (by the adhesion factor intimin), Shiga-like toxin is absorbed (causes vascular damage, oedema, thrombi). Causes thrombocytic thrombocytopaenic purpurea.

Question 14

Diagnosis of STEC? 2

Answer 14

Culture and latex agglutination tests. n.b. cooking destroys the pathogen.

Question 15

Clinical signs -rotavirus -5

Answer 15

• Calves aged 1-3 weeks
• high morbidity low mortality
• duodenum and jejunum affected - Causes malabsorption
• shed by cows and older calves - persists
• Often coupled with coronavirus infection

Question 16

Clinical signs - coronavirus -5

Answer 16

• Slightly older calves (7-22, up to 28d)
• slightly higher mortality
• ileum, caecum and colon affected
• shed by cows and older cow
• persists in environment

Question 17

Significance of the culture of salmonella = ?

Answer 17

Always significant. Reportable to the AHVLA because it is zoonotic. AB always indicated

Question 18

Which animals are affected by salmonella? How?

Answer 18

Any age of animal

Systemic illness and pyrexia

Question 19

What age do you see clinical signs in calves infected with cryptosporidium? What must you bear in mind?

Answer 19

5-14 days (n.b. PPP=2-7 days)

Question 20

Signs - cryptosporidium

Answer 20

Lower SI/colon –> villous atrophy –> malabsorption
Often concurrent disease
Resistance develops

Question 21

Signs - coccidiosis

Answer 21

Slightly older weaned calves (>3 weeks)
May –> blood stained faeces, tenesmus
May –> subclinical (poor growth rate and secondary infections as immunocompromised)

Question 22

How do you diagnose infection?

Answer 22

Faecal sample NOT swab from healthy AND affected animals. Send to competent lab. Bacteriology, virus isolation AND typing are all needed. Don’t just look at faecal appearance!

Question 23

List the ages of calves that are used as a guide to diagnose infection. 6

Answer 23

E,coli 3 weeks

Question 24

List calf factors - 4

Answer 24

• Colostrum accesibility
• Dystocia
• Competition
• Dam - cow factors, uality of colostrum, down? allowed to suck?

Question 25

List environmental features that need consideration

Answer 25

Water/feed bucket location - inside/outside pens
Contact with other calves
Deep litter
Calf Milk Replacer (CMR) vs solid feed vs. water

Question 26

How much Calf Milk Replacer (CMR) should you feed?

Answer 26

15-20% body weight per day in volume but follow packet instructions and check fat and protein levels.

Question 27

3 classes of causes of growing animal/adolescent cattle diarrhoea, give examples

Answer 27

ENDOPARASITES - ostertagia (1/2), coccidia, fluke
NUTRITIONAL - rumen acidosis, copper deficiency
INFECTIOUS - salmonella, mucosal disease (BVD PI)

Question 28

3 classes of causes of adult cattle diarrhoea, give examples

Answer 28

INFECTIOUS - MAP, salmonella, coronavirus (winter dystentery)
NUTRITIONAL - SARA
PARASITIC - fluke, ostertagia

Question 29

What must be a routine part of dairy herd management?

Answer 29

Walk around farm and observe faecal consistency of different groups of cattle.

Question 30

Clinical signs - MAP. Treatment? Zoonotic?

Answer 30

Clinical cases - severe diarrhoea and weight loss in adult cows. Infectious faeces.
No treatment or cure.
Potentially zoonotic - MAP may be involved in Crohn’s disease in humans

Question 31

How is MAP/Johne’s contracted?

Answer 31

Usually acquired by youngstock (F/O route)
Takes at least 2 years to become clinical.
Subclinical disease hard to detect or identify with lab tests

Question 32

3 main ways of preventing young animal infection. 3 other ways?

Answer 32

Preventing access to faeces of older animals/adults, infected colostrum (avoid pooled colostrum) or in utero.

• Test before buying in.
• Don’t spread slurry
• Cull out or breed to beef

Question 33

Diagnosis of MAP - how? Sensitivity vs specificty?

Answer 33

Blood test - ELISA
Low sensitivity but high specificity (positive is always a positive, negative is not always a negative). Many infected cows are not detected this way. A milk test is also available.
OTHER METHODS = ZN smear, PCR faecal, faecal culture, necropsy

Question 34

How does MAP diagnosis differ between when you are screening for infected cows versus testing clinically infected cows?

Answer 34

Diagnosis is difficult when screening for infected cows. In clinically infected cows, tests have a much higher sensitivity.