VM 575 EXAM 1 STUDY QUESTIONS AND
ACCURATE SOLUTIONS RATED A
Which part of the GI system is affected by campylobacter?
large intestine
Which enteric pathogen causes hyperplasia of the intestinal crypts?
campylobacter
What is the most important virulence factor of Clostridium?
exotoxins
How many types of Clostridium perfringens are there and what are the
types based upon?
- five types (A-E)
- based on the combination toxins produced
What type of Clostridium perfringens causes necrotic enteritis in chickens,
necrotizing enterocolotitis in pigs and hemorrhagic gastroentritis in dogs?
Type A
What type of Clostridium causes "struck" in sheep?
Type C
How does alpha toxin of C. perfringens damage the host?
breaks down host tissues by lysing host cells (phospholipase)
What type of toxin is beta toxin of C. perfringens?
pore-forming
Why are neonates more susceptible to beta toxin producing C. perfringens?
beta toxin is inactivated by trypsin, neonates have low trypsin production
,Why are younger animals less susceptible to epsilon toxin producing C.
perfringens?
epsilon toxin starts as a proto-toxin that must be activated by host proteases,
younger animals have lower intestinal proteolytic activity
Which types of C. perfringens break down tight junctions between
enterocytes?
Types A and C
Which pore-forming toxin of C. perfringens is associated with necrotic
entercolitis in horses and dogs?
NetF
What bacterium causes Johne's disease?
Mycobacterium avium subspecies paratuberculosis
T/F- Mycobacterium avium is gram positive
False, it is neither gram positive or gram negative it is acid-fast
What is the host range of M. avium paratuberculosis?
true ruminants (cattle, sheep, goats, deer)
pseudoruminants (llamas, alpacas, camels)
T/F - M. avium paratuberculosis infection is asymptomatic in many
animals
True
How is M. avium paratuberculosis transmitted?
- fecal-oral
- vertical transmission in utero
What are the stages of M. avium paratuberculosis infection?
Stage 1 - subclinical, non-detected
,Stage 2 - sub-clinical shedders
Stage 3 - clinical disease
Stage 4 - end-stage disease
Why is Johne's particularly hard to manage within a herd?
only a small percentage of infected animals will show clinical signs, others will
be asymptomatic but still shedding bacteria
The ability of what microbe to survive within marcophages and lead to
granuloma formation is a key virulence factor of what enteric pathogen?
M. avium
Which enteric pathogen is taken up by M cells in the ileum before being
engulfed by macrophages and persisting there?
M. avium
What bacterium causes potomac horse fever?
Neorickettsia risticii
How is Neorickettsia risticii transmitted?
consumpton of water containing cercariae or intermediate hosts containing
metacerariae
What disease does Lawsonia intercellularis cause in horses?
equine proliferative enteropathy
What age group of horses is typically infected with Lawsonia
intercellularis?
postweaning foals less than 1 year old
What is the only etiological agent that justifies the use of antibiotics in a
calf with scours?
E. coli
, When should antibiotics ABSOLUTELY NOT be used in a calf with scours?
if Salmonella is the etiological agent
What is the number one factor that predisposes calves to illness?
failure of passive transfer
Which parasites is piperazine active against?
- ascarids
- pinworms
How old must an animal be to safely recieve piperazine?
6 weeks
What is the mechanism of action of piperazine?
GABA agonist, causes hyperpolarization of nerve membrane and flaccid
paralysis of nematode
Why is piperazine not safe to give heartworm positive dogs?
the drug kills microfilaria
Which parasites are benzimidazoles affective against?
nematodes, trematodes, cestodes, protozoa
T/F - Benzimidazoles are ineffective against arrested larvae
True
What is the mechanism of action of Benzimidazoles?
tubulin binding causing failure of glucose uptake and starving of the parasite
Which class of antiparasitic drugs is known to be teratogenic?
Benzimidazoles
What are the two types of Macrocyclic lactones?
- Avermectins (ivermectin, doramectin)
- Milbemycins (milbemycin, moxidectin)
ACCURATE SOLUTIONS RATED A
Which part of the GI system is affected by campylobacter?
large intestine
Which enteric pathogen causes hyperplasia of the intestinal crypts?
campylobacter
What is the most important virulence factor of Clostridium?
exotoxins
How many types of Clostridium perfringens are there and what are the
types based upon?
- five types (A-E)
- based on the combination toxins produced
What type of Clostridium perfringens causes necrotic enteritis in chickens,
necrotizing enterocolotitis in pigs and hemorrhagic gastroentritis in dogs?
Type A
What type of Clostridium causes "struck" in sheep?
Type C
How does alpha toxin of C. perfringens damage the host?
breaks down host tissues by lysing host cells (phospholipase)
What type of toxin is beta toxin of C. perfringens?
pore-forming
Why are neonates more susceptible to beta toxin producing C. perfringens?
beta toxin is inactivated by trypsin, neonates have low trypsin production
,Why are younger animals less susceptible to epsilon toxin producing C.
perfringens?
epsilon toxin starts as a proto-toxin that must be activated by host proteases,
younger animals have lower intestinal proteolytic activity
Which types of C. perfringens break down tight junctions between
enterocytes?
Types A and C
Which pore-forming toxin of C. perfringens is associated with necrotic
entercolitis in horses and dogs?
NetF
What bacterium causes Johne's disease?
Mycobacterium avium subspecies paratuberculosis
T/F- Mycobacterium avium is gram positive
False, it is neither gram positive or gram negative it is acid-fast
What is the host range of M. avium paratuberculosis?
true ruminants (cattle, sheep, goats, deer)
pseudoruminants (llamas, alpacas, camels)
T/F - M. avium paratuberculosis infection is asymptomatic in many
animals
True
How is M. avium paratuberculosis transmitted?
- fecal-oral
- vertical transmission in utero
What are the stages of M. avium paratuberculosis infection?
Stage 1 - subclinical, non-detected
,Stage 2 - sub-clinical shedders
Stage 3 - clinical disease
Stage 4 - end-stage disease
Why is Johne's particularly hard to manage within a herd?
only a small percentage of infected animals will show clinical signs, others will
be asymptomatic but still shedding bacteria
The ability of what microbe to survive within marcophages and lead to
granuloma formation is a key virulence factor of what enteric pathogen?
M. avium
Which enteric pathogen is taken up by M cells in the ileum before being
engulfed by macrophages and persisting there?
M. avium
What bacterium causes potomac horse fever?
Neorickettsia risticii
How is Neorickettsia risticii transmitted?
consumpton of water containing cercariae or intermediate hosts containing
metacerariae
What disease does Lawsonia intercellularis cause in horses?
equine proliferative enteropathy
What age group of horses is typically infected with Lawsonia
intercellularis?
postweaning foals less than 1 year old
What is the only etiological agent that justifies the use of antibiotics in a
calf with scours?
E. coli
, When should antibiotics ABSOLUTELY NOT be used in a calf with scours?
if Salmonella is the etiological agent
What is the number one factor that predisposes calves to illness?
failure of passive transfer
Which parasites is piperazine active against?
- ascarids
- pinworms
How old must an animal be to safely recieve piperazine?
6 weeks
What is the mechanism of action of piperazine?
GABA agonist, causes hyperpolarization of nerve membrane and flaccid
paralysis of nematode
Why is piperazine not safe to give heartworm positive dogs?
the drug kills microfilaria
Which parasites are benzimidazoles affective against?
nematodes, trematodes, cestodes, protozoa
T/F - Benzimidazoles are ineffective against arrested larvae
True
What is the mechanism of action of Benzimidazoles?
tubulin binding causing failure of glucose uptake and starving of the parasite
Which class of antiparasitic drugs is known to be teratogenic?
Benzimidazoles
What are the two types of Macrocyclic lactones?
- Avermectins (ivermectin, doramectin)
- Milbemycins (milbemycin, moxidectin)
