Equine GI disease

Question 1

What are infectious agent causes of GI diseases in horses?

Answer 1

Salmonella
Clostridium perfringens and difficile
Rotavirus
Ehrlichia risticii

Question 2

What are symptoms of an equine GI disease?

Answer 2

Fever (+38.5)
Acute diarrhoea
Low WBC count

Question 3

What should you do if a horse is suspected of an equine GI disease (shows 2 or more symptoms)?

Answer 3

Isolate - could be contagious
Barrier nurse
Investigate
MAINTAIN HYGIENE

Question 4

Is salmonella host-specific or non-host specific? How many types of salmonella are there?

Answer 4

Can be either
Thousands of serovars
6 subspecies

Question 5

Basically describe the salmonella bacteria

Answer 5

Gram -ve
Facultative anaerobe
Facultative intracellular
Wide range of ABR

Question 6

Describe the virulence factors of the salmonella bacteria

Answer 6

Modified flagella and pilli for plasmid exchange
Adhesion molecules
Invasion genes
Virulence plasmids for extra growth, invasion and resistance
Exotoxins

Question 7

What do invasion genes in salmonella do?

Answer 7

Encode proteins that cause ruffles in enterocyte membranes

Allows salmonella to become interiorised

Question 8

What are the 3 exotoxins produced by salmonella that cause diarrhoea?

Answer 8

cAMP
Cytotoxin
Phospholipase A

Question 9

Horses susceptible to GI diseases require a lower spore dose than healthy animals. What hosts are susceptible to GI diseases?

Answer 9

Undergoing antibiotics or anthelmintics treatment
Naive immune system
Geriatric
Hospitalised
Change in feed
Stress

Question 10

How is salmonella spread? is it contagious? Is it zoonotic?

Answer 10

Contagious and zoontoic
Survives in soil for 9 months - contaminated water, feed, fomites
Recovered animals can shed for months

Question 11

Salmonella is an opportunistic infection. Without an invasion, there is no response. How does salmonella cause diarrhoea?

Answer 11

Immune system recognises endotoxins and causes inflammation and tissue necrosis
Leakage of protein and fluid
Diarrhoea
Exotoxins make inflammation, necrosis and D+ worse

Question 12

How does a host respond to salmonella?

Answer 12

Endotoxaemia triggers neutrophil dominated inflammation

Inflammation maintained by intracellular pathogens in macrophages

Question 13

Why is diarrhoea a good thing in terms of getting rid of salmonella? What is a disadvantage of this?

Answer 13

Dilutes and removes the salmonella bacteria and toxins

Can cause shock and circulatory collapse

Question 14

What needs to happen within an animal with salmonella to be able to recover?

Answer 14

Maintain hydration
Eliminate infection
Heal mucosa

Question 15

What are the main ways to control and prevent salmonella in horses?!

Answer 15

Hygiene!
Muck out infected horses last to prevent spreading faeces
Dispose soiled bedding/feed via clinical waste
Scrub with detergent, steam and culture stables
Quarantine new horses
Avoid rapid diet changes etc

Question 16

Basically describe clostridium perfringens and difficile

Answer 16

Saprophytic
Part of intestinal flora 
Gram positive
Obligate anaerobe
Haemolytic in culture
Spore forming

Question 17

What is required for clostridium to cause a GI disease?

Answer 17

Change in intestinal flora (diet change, grain overload)

Host stress

Question 18

Clostridium is spore forming. Why does this make it a difficult pathogen?

Answer 18

Extreme temperature resistant

Resitant to disinfectants

Question 19

What can be used to diagnose clostridium and why?

Answer 19

NOT culture - part of flora

ELISA of toxins

Question 20

Is C. perfringens motile or non-motile? What is the most common type in horses? What 3 toxins does it produce?

Answer 20

Non-motile
Type A
Enterotoxins, alpha toxins, B2 toxins

Question 21

Is C. difficile motile or non-motile? What toxin does it produce? What does this toxin do? What is this bacteria a significant cause of?

Answer 21

Motile
Toxin A - proinflammatory - toxic to macrophages
Significant cause of human D+

Question 22

Rotavirus has multiple strains, servers and a range of virulence. Is rotavirus host-species specific?

Answer 22

Predominantly host species specific

Question 23

What is the coat protein on rota virus? What is the significance of this?

Answer 23

VP4
Dictates susceptibility
Target Ag of Abs

Question 24

Describe the pathogenesis of rotavirus

Answer 24

Virus ingested and absorbed through intestinal villi
Causes damage and loss to cells
Vili atrophy
Poor nutrient and water absorption –> diarrhoea

Question 25

What is the incubation period of rotavirus?

Answer 25

Up to 24 hrs

Question 26

What is the duration of a rotavirus infection?

Answer 26

5-7 days

Question 27

How long do recovered animals shed rotavirus for?

Answer 27

2 weeks

Question 28

Is rotavirus contagious? How is it spread?

Answer 28

Yes
Survives up to 9 months in soil
Spread by contaminated water, feed, fomites

Question 29

Which disinfectant is effective to rotavirus? Which disinfectant is not effective?

Answer 29

Ethanol = effective
Bleach = ineffective

Question 30

How can rotavirus be diagnosed? What is the gold= standard?

Answer 30

Gold standard = electromicroscopy

Clinical signs, virus in faeces

Question 31

When is the rotavirus vaccination given to horses? What does this rely on? How long does it last?

Answer 31

At 8,9,10 months of pregnancy
Requires good passive transfer
Lasts 60 days