Foal.NeonatalGI Flashcards
Why should alpha 2 adrenergic agonists used with caution in neonates?
Due to their depressive effect on the cardiopulmonary system
Causes of diarrhea in young foals
bacteria
bacterial toxins
viruses
nutrition
parasites
antibiotic usage
At what age does the natural GI flora develop to an adult in foals?
60 days of age
What is the most important bacteria mediator of systemic sepsis in newborn foals?
Escherichia coli
Is E. coli a pathogen implicated in foal diarrhea?
No, E. coli is not likely to cause diarrhea in foals
Which clostridial toxins occur most commonly in foals?
Clostridium perfringens- biotypes A & C
Clostridium difficile
At what age range does clostridium cause diarrhea in foals?
Usually less than 36 hours of age
– with high mortality and outcomes rarely influenced by treatment
Clostridium perfringens, Biotype C produces which toxins?
alpha
beta
enterotoxin
What two principle toxins are produced by C. difficile?
enterotoxin (toxin A)
Cytotoxin (toxin B)
Besides the primary “big pathogens” of diarrhea in foals, what other bacteria are implicated in causing diarrhea in foals?
Bacteroidis fragilis (gram neg anaerobic rod)
Enterococcus (Group D Streptococcus) durans
Aeromonas hydrophila
Rhodococcus equi
What is the most common source of Salmonella to foals?
Mares shedding salmonella
**rare that both develop disease
In contrast to adult infections, detectable bacteremia occurs commonly in affected foals, with what bacterial pathogen?
Salmonella
What is the most common viral cause of diarrhea in foals?
Rotavirus
How many groups of rotavirus are there? and which is the most common cause of diarrhea in foals?
7 known groups (A-G)
- Gorup A, serotype G3 most common serotype
Why are there many variations of rotavirus?
Rotaviruses have the ability to change their surface proteins over time
– rearrangement gene segments takes place during coinfections with other strains
Rotavirus pathogenesis:
Where does rotavirus replicate?
invades lining of the proximal small intestine
–> villous cell death and resultatnt loss of absorptive area
Rotavirus pathogenesis:
Mechanisms involved in diarrhea
- loss of absorptive capacity coupled with a decrease in lactase production can lea to an osmotic load of undigested lactose delivered to an immature hind gut
- compensatory crypt cell proliferation may cause an increase in intestinalis secretion
- virus produces an enterotoxin that causes or contributes to the development of diarrhea
Which rotavirus enterotoxin and cytotoxin is primarily responsible for diarrhea?
NSP4
-nonstructural glycoprotein of rotavirus released from virus infected enterocytes
-noncompetitive inhibitor of Na-glucose symporter and enhances intestinal chloride secretion
What age range is rotavirus diarrhea seen in foals?
between 2 and 160 days, most common younger than 60 days old
What is a common parasite of foals?
streongyloides westeri
When are foals exposed to Strongyloides westeri?
early infection occurring through mare’s milk
Cryptosporidium differs from coccidia by which factors?
- differs in size: 4-6 microm compared with 23 to 34 microm for other coccidia
- host specificity (not host specific)
- pathogenesis (only invades epithelium)
- drug sensitivity (resistant to many drugs)
Is cryptosporidium has bene difficult to pharmacologic control, what drugs may be efficacious?
paromomycin
nitazoxanide
azithromycin
Shedding of Cryptosporidium in foals occurs bettween what age range?
4 to 19 weeks of age, and persisted no more than 4 weeks.