Lecture 3 - Fever of unknown origin (FUO) (Cooke) Flashcards
where does thermoregulation occur in the brain
anterior hypothalamus
increase production of heat by
catecholamines
thyroxine
shivering
decrease heat loss by
vasoconstriction
piloerection
postural changes
seeking warmth
lose heat by
panting vasodilation postural change seek cool enviro grooming (cat)
__ hyperthermia is a true fever
pyrogenic
__ causes of hyperthermia include exercise, heat stroke pathologic, pharmacologic, inadequate heat loss
non-pyrogenic
thermoregulation is mediated by
pyrogens (exogenous and endogenous)
exogenous pyrogens
infectious (bacteria/LPS, viral, fungal)
immune complexes
inflammation
drugs (tetracycline)
these are indirect causes of increased body temperature, these stimulate the endogenous pyrogens
endogenous pyrogens
IL1 and 6
TNF
IFN
these bind to endothelial cells in anterior hypothalamus to stimulate production of PGE1&2 (prostaglandins) which increases the core BT
__ bind to vascular endothelial cells which then release ___ causing BT to rise
IL1, IL6, TNF, IFN
PGE
cat with decreased appetite and repeatable temperature above 104F; pyogenic or non-pyogenic (stress)
pyogenic
benefits of increasing BT
Protective;
i virus replication
kill microorgs
cons of increasing BT
increased metabolic state and O2 consumption
suppressed appetite
most common categories for FUO
Infectious IM neoplatic inflamm drugs/toxin
*most due to top 3
cardiac murmur could indicate
endocarditis
spinal lesion or pain could indicate
discospondylitis, meningitis
pain on long bones
panosteitis or osteomyelitis
painful muscles
polymyositis
if there is no localization for FUO then must take a __ approach to diagnostics
staged;
stage 1 less invasive basic tests (MDB, HW, FeLV/FIV, rads, urine culture)
stage 2 more expensive (ultrasound, blood culture, FNAs, echo, dz titers)
stage 3 more invasive and expensive (bronchoscopy, CSF tap, dental rads, BM asp, CT, etc)
a 14yo GSD decreased appetite with 104F and unremarkable PE; use a staged or problem based approach for diagnostics? what would you start with?
staged; nothing to localize for a POMA
MDB including a blood smear eval!
when doing a MDB for a FUO what should you always look at
blood smear
IM dz is a common cause of FUO; even if joints are unremarkable and there is no pain or lameness a __ may still be helpful
joint taps (polyarthropathy doesn’t always appear as lameness, joint swelling and pain)
if do tests and nothing is diagnostic what can you try next
therapeutic trial to get a tentative dx
must use appropriate dose and duration and consider that any resolution could be coincidental
suspected IMHA and started therapeutic trail with steroids but patient got worse, why?
exacerbated underlying dz (babesia)
how should you treat a fever
fluid therapy
+/- antipyretic agents if dangeroulsy high (106F)
should not treat a fever with cooling techniques like a non-pyrogenic hyperthermia! Body will generate more heat to warm self back up.
how do antipyretic agents work (MOA)?
COX inhibitors (NSAIDs) block production of prostaglandins (PGE) which cause body to increase temperature
joint tap revealed non-degenerative neuts
polyarthritis; IM polyarhropathy responds to IS steroids
