Fever/Immune Flashcards
what is the difference between a fever and hyperthermia?
fever is a raised thermoregulatory set point, set by the anterior hypothalamus and the presence of pyrogens
with hyperthermia there is no alteration of the thermoregulatory set point, can be caused by exercise, seizures, stress, etc
what are the things that cause fever?
the knights who say NIII
neoplasia, infection, immune mediated, inflammation
what is a FUO?
fever of unknown origin: when fever persists long enough to where the common self limiting causes are ruled out and initial diagnostics do not reveal a cause for a fever
a dog presents for fever. what history questions will you ask the owner?
- travel history?
- any recent medications?
- recent history of fighting or trauma?
- recent heat? (pyo)
- any animals or humans in close contact showing signs?
what sorts of things might you be looking for on PE with a pet with a fever?
heart murmur, joint effusion, back pain, bone pain, bite wounds, renal pain, organ enlargement, rectal exam, masses, URI, lung auscultation, enlarged LNs, abdominal or chest effusion, oral exam, ocular exam, derm lesions?
what are some first line diagnostic tools you can use for working up a fever?
CBC/blood smear, biochemistry, urinalysis, urine culture, FeLV, FIV in cats, imaging
others: ultrasound, echocardiogram, joint taps, FNAs, biopsies, etc
autoimmune diseases are most mediated by ___ cells and ______
Th2 cells and autoantibodies
what are 3 characteristics of immune mediated diseases and therefore 3 treatment targets?
-autoantibody production by lymphocytes
-opsonized cells cleared by marcophages or complement
- inflammatory cytokines
what is the difference between primary and secondary autoimmune disease
primary is idiopathic and is a diagnosis of exclusion
secondary has an underlying cause you can identify
immune mediated diseases require complete workups to:
look for an underlying cause and rule out infectious etiology BEFORE you suppress the immune system
what us SLE?
systemic lupus erythematosus
a multisystemic autoimmune disorder where there are antibodies against many tissues, including the nucleus of cells. opsonization happens as well as the formation of immune complexes.
common in dogs, GSDs and duck tollers, usually middle aged
a 6 yo duck toller presents for fever and joint swelling. upon further examination you notice skin lesions on the muzzle and in the oral cavity. The LNs are enlarged. differential? what diagnostics tests do you want?
systemic lupus erythematosus
hard to diagnose with 100% certainty
first, rule out underlying disorders. consider a urinalysis to check for proteinuria which could be indicative of glomerulonephritis
ideally do a ANA test (antinuclear antibody test) or a LE test
what is the ANA test?
autonuclear antibody test for SLE. tests for antibodies agaisnt DNA, RNA, and hostones. false positives and false negatives possible.
usually an ELISA test
what is an LE test?
for SLE diagnosois
looking for lupus erythematosus cells: neutrohpils containing phagovytized nucleus. not sensitive, but very specific.
the 6yo duck toller tests positive for the ANA test and the LE test. how will you treat and what is the prognosis?
immunosuppressive therapy
adjunct therapy for secondary issues like IMHA or PLN
supportive care
prognosis is variable and relapse is very possible
what causes non inflammatory joint disease?
developmental joint disease (like OCD)
degenerative (like arthritis)
trauma
tumors
what can cause inflammatory joint disease?
either septic or sterile, will see neutrophils in the joint
septic: bacterial infection
immune complexes: type III hypersensitivity reaction, complexes depositied in joints, activating complement and inflammation
sterile: inflammation within the joint itself
how do you differentiate between an infectious joint disease and an immune mediated joint disease?
septic: more likely a single swollen joint, history or surgery or trauma, or a previous infection
immune: multiple joints, often smaller more distal joints, history of antibiotic or vaccination
how do you differentiate between septic and sterile joints?
sample the synovial fluid
when should you consider doing a joint tap?
if you have solitary joint disease with signs of inflammation or systemic illness, evidence of polyarthritis, or if you have a FUO
ALWAYS CULTURE A JOINT TAP
what does normal joint fluid look like?
clear, colorless, viscous, with low cellularity, mononulcear cells and very few neutrophils
what does abnormal joint fluid look like?
turbid, cloudy, discolored (pink or yellow), very thin, high cellularity with many neutrophils and maybe some bacteria
describe synovial fluids results for a :
sterile inflammatory joint
a septic joint
degenerative or traumatic joint
sterile: thin, turbid, discolored, cellularity between 3000-150,000 cells/uL, non degenerative neutrophils
septic joint: thin, turbid, discolored, cellularity more than 150,000/uL, degenerative neutrophils, maybe bacteria
degenerative: clear,colorless, could be blood with trauma, low or slightly elevated cellularity, mononuclear cells
what is erosive polyarthritis ?
subchondral bone is destroyed, usually carpal bones, happens in small middle aged dogs. very UNCOMMON
what are the most common causes of inflammatory joint disease in small animals?
idiopathic most common
SLE
reactive/secondary
what is IMPA?
immune mediated polyarthritis, where immune complexes deposit in the synovium. can be primary/idiopathic, or reactive/secondary
what sorts of things can cause reactive/secondary IMPA?
infectious anywhere in the body or from bacteremia
medications like antibiotics or vaccines
neoplasia
dietary elements (uncommon)
list some clinical signs of IMPA
stiff gait/walking on eggsehlls, joint pain or swelling, inappetence, lethargy, weight loss, weakness, vomiting, fever, neck or back pain
how do you diagnose IMPA?
joint tap: neutrophilic inflammation in multiple joints, negative culture
good PE, CBC/chem, urinalysis, infectious disease testing, imaging
what is important to remember about doing a joint , urine, or blood culture?
ideally do this before antibiotic therapy
do sterile prep, wear sterile globes, etc
what is a SNAP 4DX / Accuplex test?
tests for tick borne diseases: anaplasma, borrela burgdorferi (lyme), ehrlichia, etc, and heartworm
if you think a patient could have IMPA, when would you consider doing joint radiographs?
if there’s a single joint affected, if there is any crepitation or instability, decreased range of motion
a 3 yo MN golden retriever has a 3 week hx of intermittent lethargy, fever, and decreased appetite, and was on antbiotics 3 weeks ago. he travels to ontario and manitoba. on PE, his right carpus seems painful, there is some mild effusion of the left hock, and his temp is 40.1. what are your next steps?
CBC/chem/UA
joint taps/cultures
SNAP 4DX
the 3yo MN golden retreiver’s results for CBC chem: 2+ protein in urine, and a stress lymphopenia. SNAP 4DX is negative.
joint tap: thin and cloudy, lots of neutrophils (increase in cellularity), and all joints are affected. his urine culture, blood culture, and joint culture are all negative. diagnosis? treatment?
IMPA, but we can’t say yet if it’s primary or secondary! we need more diagnostics like US, rads, diet analysis.
treatment: prednisone 2mg/kg/day
after treating the 3yo MN golden with prednisone, what is your follow up plan?
repeat joint tap in 1 month before tapering prednisone.
3yo MN golden is clinically better, but the joints are not responding to the prednisone you gave him. next steps?
add in cyclosporin
Dopey a 8yo MN basset hound presents for lethargy, lameness, inappetence. 1.5 weeks ago became lame on RH leg and rads sus of early cruciate disease, was given rest and NSAIDs. 1 week ago he is unable to walk and is lethargic. temp is 39.9 and chest rads sus of penumonia came back normal. on PE: slightly tacky mms, reluctant to move, 2/6 systolic heart murmur, and maybe some mild joint effusion. on CBC chem he showed inflammation, a mild anemia, and his 4DX is negative. joint taps are cloudy and pink, watery. SO many neutrophils were found, but they are non-degenerative. on echocardiogram he showed signs suggesting endocarditis! blood and urine culture showed E coli but the joint cultures were negative. diagnosis?
endocarditis with reactive/secondary IMPA
clinical signs of bacterial endocarditis?
lameness, heart failure, fever, tachycardia, murmur.
PE: newly developed or change in heart murmur with concurrent signs like fever or joint disease
how do you treat bacterial endocarditis
bactericidal broad spec antibiotics, commonly aminoglycosides, beta lactams, or fluoroquinolones. also will need to reat the cardiac disease, and possible thromboprophylaxis to prevent clots from forming. treatment 4-6 weeks minimum, usually longer
