Exam 1 - Infectious GI Disease Flashcards
what is definitive care?
treatment aimed to eliminate illness
example - fenbendazole for treating giardia
what are the 2 agents mainly involved in canine viral enteritis?
parvo & coronavirus
what 2 agents are mainly involved in bacterial enteritis of cats & dogs?
salmonella & campylobacter
what is the main agent involved in causing protozoal diarrhea in small animals?
giardia
T/F: no clinical presentation of enteritis is pathognomonic
true - there is a lot of overlap with clinical signs & diagnosis may matter for prognosis more than therapy
what is enteritis?
inflammation of the gut - can be infectious or not
diarrhea is the most typical sign but vomiting can also be seen
what viral agent causes the classic canine parvo?
CPV-2
what does CPV-1 cause in dogs?
fading puppy syndrome - limited pathogenicity
what is the morphology of canine parvovirus? when did we start seeing it in dogs?
small, non-enveloped, hardy DNA virus - CPV-2 is host range limited to canidae
jumped from cats & emerged in the 70’s - substrains 2a/2b/2c evolving since
what is the pathogenesis of canine parvovirus?
highly contagious virus through oronasal exposure - causes a systemic viremia with a tropism for rapidly dividing cells such as the gi epithelium, lymph nodes, thymus, & bone marrow
see mucosal collapse with increased permeability, decreased absorption, decreased secretion, & crypt cell damage in the gut
what is the typical incubation period for parvo prior to clinical signs appearing? when is the virus shed?
4-6 days but up to 14 before clinical signs
fecal shedding occurs during the incubation period & continues during the symptomatic period
T/F: an animal without clinical signs can be shedding parvovirus
true - shedding occurs during incubation
what are the main clinical signs of parvo?
acute severe vomiting & diarrhea that is often bloody leading to panhypoproteinemia & often worsened by concurrent infections
lethargy, anorexia, abdominal pain (due to enteritis, sloughing, cytokines), dehydration, & malnourishment
T/F: a dog with parvo is at risk for developing an intussusception
true
T/F: widespread vaccination has decreased the occurrence of parvovirus myocarditis because most vaccinated dams pass antibodies to their puppies
true - only seen on occasions
if you have a parvo patient that has signs of myocarditis and is <6 weeks of age, what does this imply?
late in utero infection - dam was not immune
when was myocarditis seen with parvo?
in early existence of the virus - heart failure occurred alone with gi signs or when gi signs were regressing
structural cardiac damage was irreversible & uniformly fatal
how is parvo diagnosed?
history/physical exam - highly sensitive but less specific
cbc - leukopenia, specifically neutropenia, & lymphopenia
chem - hypoproteinemia, possibly hypoglycemic/electrolyte disturbances
fecal parvo Ag SNAP test - patient side, highly specific but less sensitive
fecal PCR - send out, highly sensitive & specific
if a puppy presents to you with signs of parvo, what patient side diagnostic test do you want to run that is highly specific but less sensitive? why? what test could you send out in case it comes back negative?
fecal parvo antigen snap test
virus is only shed for about 72 hours during clinical illness
fecal PCR
why is the main treatment for parvo symptomatic & supportive? what does this mean?
symptomatic - preventing or treating, as early as possible, the symptoms of the disease and the side effects caused by treatment of the disease (example - anti-emetics)
supportive - pain management, nutritional support
it is a virus - want to help the body get through it, antibiotics for secondary infections/help immune system, support nutrition
T/F: early enteral nutrition through an NG tube reduced hospitalization time in parvo patients
true - also allows for suction of residual gastric contents prior to feeding
how should you feed a parvo patient with an NG tube?
start at 25% RER & trickle feed using a CRI pump if 24 hour care
if not - intermittent syringe feeding & always position them in sternal
T/F: parenteral nutrition for parvo patients is expensive, complicated, & risks sepsis in neutropenic patients
true
‘if the gut works, use it’ - what does this mean for treating parvo patients? what should you do if the animal is vomiting?
the gi contents are nourished from the luminal contents
rest the gi tract - 12 hours after last vomiting episode
_______ is often a cause of mortality in parvo patients due to expensive treatment
euthanasia
what are some potential complications associated with parvo virus infections?
aspiration pneumonia, intussusception, sepsis, & esophageal strictures
T/F: timing is critical in parvo patients with puppies surviving the first 3 days having a better chance at recovery
true
how is parvo prevented in dogs?
core vaccine starting at 6 weeks & boostered every 3-4 weeks until 16 weeks old - boostered again at 1 year, & every 3 years after (dogs are likely boosted through natural environmental exposure
MLV for sterilizing immunity - don’t give to pregnant bitches
disinfect areas with bleach, accelerated H2O2, steam/autoclave, direct sunlight/drying
coronavirus has a tropism for what cells?
gi epithelium at villus tips
what is the incubation period & shedding period of coronavirus?
short incubation & long shedding period whether or not the animal shows clinical signs
T/F: despite widespread seropositivity, many animals are never symptomatic for coronavirus
true
how is coronavirus spread in small animals?
fecal-oral - most commonly in high density environments
what is the morphology of coronavirus?
collection of closely related viruses that can infect most domestic species - enveloped ssRNA virus that isn’t very durable in the environment
what are some clinical signs associated with enteric coronavirus in small animals?
none
acute, mild diarrhea occasionally with vomiting - fever is unlikely & no leukopenia
chronic watery diarrhea that isn’t hemorrhagic (severe clinical signs more commonly seen in animals with comorbidities)
T/F: a positive serology result for coronavirus in a dog indicates current infection
false - indicates exposure (widespread disease)
a positive PCR or EM of feces indicates shedding that is prolonged after infection
T/F: there are no helpful labwork changes to help guide you in diagnosing coronavirus infection in small animals
true
how is coronavirus treated?
diagnose & treat whatever else is wrong (parasites, parvo, enteric bacterial infection)
supportive care - most needed in juveniles or severe cases of dehydration
consider husbandry changes
T/F: coronavirus is vaccinated against in both canine & feline core vaccine protocols
false - not at all
MLV & inactivated products are available but are likely ineffective
what is the treatment for parvo patients?
symptomatic & supportive care
fluid therapy +/- colloids
antibiotics to block gi flora translocation, anti-emetics, pain management, nutrition, & impeccable nursing care in isolation
what are clinical signs of bacterial enteritis?
presence of a particular pathogenic bacterial population (strong pathogen)
imbalance in proportions of types - dysbiosis
gut is full of bacteria - mixed population is normal, not just tolerated, but necessary
what clinical signs can e. coli cause in small animals? is it a part of the resident flora of the gi tract?
resident flora
UTI, pneumonia, or direct invasion of gut wall causing diarrhea
T/F: some species of helicobacter can cause gastric ulcers & others hepatitis in people
true
T/F: clostridial species can produce toxins - including tetanus toxins, under the right conditions, even though it is a part of the resident flora of the gi tract
true
what campylobacter species is most commonly associated with diarrheal disease in small animals?
campylobacter jejuni
what is the morphology of campylobacter?
genus of g- motile, spiral rods - diverse species with some host preferences but lots of overlap
generally adherent/non-invasive, may produce toxins - more invasive in people causing systemic sugns
how is campylobacter transmitted?
fecal oral exposure - includes fomite contamination of food
animals affected by campylobacter are more likely: _______?
young - under 6 months
stressed - household changes, surgery, pregnancy
experiencing co-infections
what clinical signs are associated with campylobacter bacterial enteritis?
mucoid to watery to bloody diarrhea - large intestinal or mixed type
fever, lethargy, anorexia, vomiting, leukocytosis, or leukopenia if they become septic
why does it matter that many dogs & cats are asymptomatic with campylobacter enteritis?
there is a zoonotic risk!!
people are more susceptible to infection & get more systemically ill than pets
T/F: a fecal smear cytology with ‘seagulls’ should be plentiful for diagnosing campylobacter, but it is not a definitive diagnosis
true
how is campylobacter bacterial enteritis diagnosed in small animals?
history/physical exam - husbandry, age, & clinical signs
fecal smear cytology - leukocytes may be seen
PCR or species-specific culture to confirm
need to consider alternate or concurrent diseases
how is campylobacter enteritis prevented?
better husbandry - cook pets’ food, minimize crowding, maintain sanitary environment at appropriate temperature, & deworm appropriately
concern for zoonotic risk - client education about hygiene!!! people are more susceptible to infection & get more systemically ill than pets
what is the goal of treatment for campylobacter enteritis?
resolution of clinical signs - symptomatic & supportive care tailored to severity of signs
why should you be careful with definitive therapy for treating campylobacter enteritis?
BE CAREFUL - may use erythromycin, chloramphenicol, & quinolones - pay attention to puppy’s source, may need to do culture & susceptibility
antibiotics will further disrupt the gi flora & complete eradication of campy is not likely or necessary in most cases
what is the morphology of salmonella enterica?
genus of g- motile facultatively anaerobic rods - considered a single pathogenic species with many serotypes with most serotypes NOT BEING HOST SPECIFIC (affects mammals, birds, reptiles)
what is the damage caused by salmonella enterica?
invasive species that may produce toxins - will cause enterocyte sloughing leading to severe diarrhea
allows for systemic spread leading to endotoxemia & bacteremia
what is the pathogenesis of salmonella enterica?
fecal oral exposure (food or fomites) that is very durable in water sources - can also be isolated from cooked food in dirty environments
T/F: clinical signs of salmonella enterica depends on host factors, strain factors, of dose
true
what animals commonly show clinical signs with salmonella enterica?
old, young, immune-compromised, & those stressed by the environment or co-morbidity
T/F: an animal can be an asymptomatic carrier of salmonella & may never show signs of illness
true - may shed 6 weeks or more after clinical recovery if showing signs
what clinical signs are seen with salmonella bacterial enteritis?
gastroenteritis - both small & large bowel, fever, lethargy, anorexia, vomiting, diarrhea (may be bloody), abdominal pain, & clinical signs may last weeks with shedding persisting after resolution of clinical signs
+/- septicemia - may lead to shock or death
+/- organ infections - abscesses anywhere following bacteremia
how is salmonella bacterial enteritis diagnosed?
history/physical exam
labwork varies based on clinical syndrome - leukocytosis including left shift in many cases, neutropenia in severe cases (juveniles), & chemistry reflects dehydration or particular organ involvement
fecal salmonella specific culture or PCR - isolation of salmonella from sterile site is definitive, fecal smear may show chaining rods but can’t identify it on microscope alone
what is the treatment for salmonella bacterial enteritis?
symptomatic & supportive care tailored to the severity of signs - may be self-limiting
hospitalize (isolation) if needed - attentive monitoring to guide therapeutic adjustments
be very careful with definitive therapy
why should you be very careful with definitive therapy for an animal with salmonella bacterial enteritis?
antibiotics will disrupt gi flora - may use empiric beta lactams & quinolones pending culture & susceptibility
rapidly growing bacteria may rapidly acquire & share resistance
how is salmonella bacterial enteritis prevented?
better husbandry - cook pets’ food, wash hands, maintain cleanliness in kennels/shelters/clinics, & isolate affected animals
why is there a major zoonotic concern for animals with salmonella bacterial enteritis?
need client education - particular risk from reptiles (large proportion carry as normal flora) & need to be concerned about young children, elderly people, & immunocompromised
increasing documentation of multi-drug resistant strains
what are the 2 morphologic forms of giardia?
trophozoite in the gut - motile, adherent, short lived
cyst - excreted into the environment, highly resistant in moist & cold conditions but can be desiccated by dry & hot conditions
T/F: giardia can complete its lifestyle within a single host
true
what is this?
giardia trophozoite - smiley face sting ray looking thing
what agent is this?
giardia cysts
T/F: giardia usually causes no clinical signs
true
what animals typically do have clinical signs of giardia?
very old, very young, immunocompromised, those with comorbidities, & those house in dense or unsanitary conditions
what clinical signs are associated with giardia?
chronic small bowel diarrhea & weight loss - may be mucoid or fatty
not hemorrhagic - no vomiting
afebrile & normal labwork
T/F: diagnosing giardia is very hard
true
what is the gold standard of diagnosing giardia?
fecal IFA
what are some different ways to diagnosis giardia?
fecal direct smear to look for trophozoites - fragile/dies quickly, must confirm identity
fecal concentration/floatation to look for cysts - cysts are shed intermittently, so 3 negative samples over a week must be proved to call it negative
snap elisa - unclear on how presence of detectable antigen correlates to symptomatic infection
pcr - unclear on how presence of detectable DNA correlates to symptomatic infection
T/F: there is a wide disagreement about treatment of asymptomatic giardia cases in small animals
true - the treatment goal is the resolution of clinical signs
what is the treatment of choice for giardia in symptomatic cases? why?
what husbandry changes should be made?
fenbendazole - extremely cheap, limited to no side effects (less disruption of gi flora), & might be indicated for other parasites anyway
probiotics & fiber, bathe & thoroughly dry patients, & environmental hygiene
how is giardia diarrhea prevented?
husbandry!!!! maintain dryness & cleanliness in kennels, shelters, & clinics
avoid exposure to contaminated yards & water sources
is there a zoonotic risk associated with giardia?
uncertain - humans do get giardia but unsure if it is transmitted directly from pets
theoretical risk for very old, very young, & immunocompromised people
how is an asymptomatic giardia fecal-positive case managed?
still treat - potential risk of zoonosis
what is the pathogenesis of giardia?
fecal oral route (fomites, water)
encyst in gut lumen & trophozoites adhere to microvilli
how does giardia cause clinical signs?
mechanisms by which trophozoites cause disease is poorly understood but potentially due to -
secretion due to inflammation, malabsorption due to microvilli loss
what is sensitivity?
ability of the test to accurately identify a positive result in an animal that has the disease
what is specificity?
probability that an animal that does not have the disease will test negative
likelihood that a healthy, disease free animal will get a negative test result
what is positive predictive value?
probability that a sick animal has a positive test result
the probability that an animal has the disease given that the test is positive
what is negative predictive value?
likelihood that a healthy, disease free animal will get an accurate negative test result
probability that an animal that tests negative does not have the disease
T/F: sensitivity & specificity are independent of prevalence
true
_______/_______ are features of the tests
sensitivity/specificity
_______/_______ _______ _______ are features of how you use a test
positive & negative predictive value
T/F: sensitivity & specificity evaluate your diagnostic test’s ability to determine if an animal has a disease or does not have a disease
true
if you are thinking your patient has a bacterial cause of enteritis, what 2 agents must you include on your differential list & why?
campylobacter & salmonella
both affect similar populations, have the same clinical signs, & require the same work up/therapy/client education/zoonotic risk
