Lecture 3 - Fever of unknown origin (FUO) (Cooke)

Question 1

where does thermoregulation occur in the brain

Answer 1

anterior hypothalamus

Question 2

increase production of heat by

Answer 2

catecholamines
thyroxine
shivering

Question 3

decrease heat loss by

Answer 3

vasoconstriction
piloerection
postural changes
seeking warmth

Question 4

lose heat by

Answer 4

panting 
vasodilation
postural change 
seek cool enviro
grooming (cat)

Question 5

__ hyperthermia is a true fever

Answer 5

pyrogenic

Question 6

__ causes of hyperthermia include exercise, heat stroke pathologic, pharmacologic, inadequate heat loss

Answer 6

non-pyrogenic

Question 7

thermoregulation is mediated by

Answer 7

pyrogens (exogenous and endogenous)

Question 8

exogenous pyrogens

Answer 8

infectious (bacteria/LPS, viral, fungal)
immune complexes
inflammation
drugs (tetracycline)

these are indirect causes of increased body temperature, these stimulate the endogenous pyrogens

Question 9

endogenous pyrogens

Answer 9

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

Question 10

__ bind to vascular endothelial cells which then release ___ causing BT to rise

Answer 10

IL1, IL6, TNF, IFN

PGE

Question 11

cat with decreased appetite and repeatable temperature above 104F; pyogenic or non-pyogenic (stress)

Answer 11

pyogenic

Question 12

benefits of increasing BT

Answer 12

Protective;
i virus replication
kill microorgs

Question 13

cons of increasing BT

Answer 13

increased metabolic state and O2 consumption

suppressed appetite

Question 14

most common categories for FUO

Answer 14

Infectious
IM
neoplatic
inflamm
drugs/toxin 

*most due to top 3

Question 15

cardiac murmur could indicate

Answer 15

endocarditis

Question 16

spinal lesion or pain could indicate

Answer 16

discospondylitis, meningitis

Question 17

pain on long bones

Answer 17

panosteitis or osteomyelitis

Question 18

painful muscles

Answer 18

polymyositis

Question 19

if there is no localization for FUO then must take a __ approach to diagnostics

Answer 19

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)

Question 20

a 14yo GSD decreased appetite with 104F and unremarkable PE; use a staged or problem based approach for diagnostics? what would you start with?

Answer 20

staged; nothing to localize for a POMA

MDB including a blood smear eval!

Question 21

when doing a MDB for a FUO what should you always look at

Answer 21

blood smear

Question 22

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

Answer 22

joint taps (polyarthropathy doesn’t always appear as lameness, joint swelling and pain)

Question 23

if do tests and nothing is diagnostic what can you try next

Answer 23

therapeutic trial to get a tentative dx

must use appropriate dose and duration and consider that any resolution could be coincidental

Question 24

suspected IMHA and started therapeutic trail with steroids but patient got worse, why?

Answer 24

exacerbated underlying dz (babesia)

Question 25

how should you treat a fever

Answer 25

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.

Question 26

how do antipyretic agents work (MOA)?

Answer 26

COX inhibitors (NSAIDs) block production of prostaglandins (PGE) which cause body to increase temperature

Question 27

joint tap revealed non-degenerative neuts

Answer 27

polyarthritis; IM polyarhropathy responds to IS steroids