Equine GI disease Flashcards
What are infectious agent causes of GI diseases in horses?
Salmonella
Clostridium perfringens and difficile
Rotavirus
Ehrlichia risticii
What are symptoms of an equine GI disease?
Fever (+38.5)
Acute diarrhoea
Low WBC count
What should you do if a horse is suspected of an equine GI disease (shows 2 or more symptoms)?
Isolate - could be contagious
Barrier nurse
Investigate
MAINTAIN HYGIENE
Is salmonella host-specific or non-host specific? How many types of salmonella are there?
Can be either
Thousands of serovars
6 subspecies
Basically describe the salmonella bacteria
Gram -ve
Facultative anaerobe
Facultative intracellular
Wide range of ABR
Describe the virulence factors of the salmonella bacteria
Modified flagella and pilli for plasmid exchange
Adhesion molecules
Invasion genes
Virulence plasmids for extra growth, invasion and resistance
Exotoxins
What do invasion genes in salmonella do?
Encode proteins that cause ruffles in enterocyte membranes
Allows salmonella to become interiorised
What are the 3 exotoxins produced by salmonella that cause diarrhoea?
cAMP
Cytotoxin
Phospholipase A
Horses susceptible to GI diseases require a lower spore dose than healthy animals. What hosts are susceptible to GI diseases?
Undergoing antibiotics or anthelmintics treatment Naive immune system Geriatric Hospitalised Change in feed Stress
How is salmonella spread? is it contagious? Is it zoonotic?
Contagious and zoontoic
Survives in soil for 9 months - contaminated water, feed, fomites
Recovered animals can shed for months
Salmonella is an opportunistic infection. Without an invasion, there is no response. How does salmonella cause diarrhoea?
Immune system recognises endotoxins and causes inflammation and tissue necrosis
Leakage of protein and fluid
Diarrhoea
Exotoxins make inflammation, necrosis and D+ worse
How does a host respond to salmonella?
Endotoxaemia triggers neutrophil dominated inflammation
Inflammation maintained by intracellular pathogens in macrophages
Why is diarrhoea a good thing in terms of getting rid of salmonella? What is a disadvantage of this?
Dilutes and removes the salmonella bacteria and toxins
Can cause shock and circulatory collapse
What needs to happen within an animal with salmonella to be able to recover?
Maintain hydration
Eliminate infection
Heal mucosa
What are the main ways to control and prevent salmonella in horses?!
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
Basically describe clostridium perfringens and difficile
Saprophytic Part of intestinal flora Gram positive Obligate anaerobe Haemolytic in culture Spore forming
What is required for clostridium to cause a GI disease?
Change in intestinal flora (diet change, grain overload)
Host stress
Clostridium is spore forming. Why does this make it a difficult pathogen?
Extreme temperature resistant
Resitant to disinfectants
What can be used to diagnose clostridium and why?
NOT culture - part of flora
ELISA of toxins
Is C. perfringens motile or non-motile? What is the most common type in horses? What 3 toxins does it produce?
Non-motile
Type A
Enterotoxins, alpha toxins, B2 toxins
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?
Motile
Toxin A - proinflammatory - toxic to macrophages
Significant cause of human D+
Rotavirus has multiple strains, servers and a range of virulence. Is rotavirus host-species specific?
Predominantly host species specific
What is the coat protein on rota virus? What is the significance of this?
VP4
Dictates susceptibility
Target Ag of Abs
Describe the pathogenesis of rotavirus
Virus ingested and absorbed through intestinal villi
Causes damage and loss to cells
Vili atrophy
Poor nutrient and water absorption –> diarrhoea
