FA Med Q3, IV
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how is staph aureus diagnosed?
- -coagulase positive
- -double zone of hemolysis
how is staph aureus mastitis treated?
- *Dry therapy + long term IMM Abs*
- Systemic Ceftiofur/cloxacillin
- (Some B- lactam Resistence)
how is staph aureus prevented? 4
- separate infected; cull non-responsive cows
- Tx at dry off and teat sealant
- No unpasteurized milk for calves
- Teat Dip at milking
Strep. agalactiae is another highly contagious mastitis pathogen. what form does it cause (acute/chronic/subclinical,etc)?
- Subclinical with Peracute local inflammation
- (if bulk tank SCC increases suddenly look for this bacteria!)
where is strep ag found?
- only in the mammary gland - multiplies in milk but doesn't go deep
- +/- cistern - fibrosis if chronic
how does cow present with typical strep ag mastitis?
- no clinical signs of systemic illness (poss. febrile)
- abnormal strip cup
- positive CMT
how is strep ag diagnosed?
- culture via cAMP test;
- cAMP+ (arrow shaped hemolysis) = infection
how is strep ag treated?
- early IMM tx successful (systemic usu. not needed)
how is strep ag prevented? 4
- proper milking hygiene
- dry cow therapy
- pre/post dipping
- *eradication w/vigilance is possible*
what is the less common cause of contagious mastitis that can cause "sandy like" milk secretions that can be watery to purulent?
what are clinical signs associated with mycoplasma bovis?
- Herd c/s:
what is a common cause of mycoplasma bovis mastitis flare ups?
Is it safe to feed this milk to calves?
- No - can spread systemically
where can you collect samples to look for mycoplasma bovis?
- mucous membranes and secretions from respiratory and urogenital tracts
- (infection highest in calves and heifers)
how is mycoplasma diagnosed?
special media required, would be negative on routine culture
how is mycoplasma treated?
- does NOT respond to routine tx - life long carriers - cull
- if choose to tx, need macrolides systemically (no intramammary macrolides exist)
what are 5 things that should could happen present on the farm that would lead to to consider mycoplasma bovis outbreak?
- 1- mastitis after pneumonia problems
- 2- calf joint swellings/lameness
- 3- calf head tilt/inner ear infection
- 4- cows with new knee/hock swellings
- 5- multiple quarters non responsive to tx; sandy milk; neg. routine culture
what are 2 major environmental pathogens causing mastitis?
- e. coli (poor conditions)
- klebsiella (saw dust shavings)
what are 2 minor environmental pathogens causing mastitis?
are coliform infections more prevalent when gram positive infections are controlled or when there is an outbreak?
- coliforms more when G+ is controlled
- (low SCC can lead to coliform mastitis)
why do coliforms proliferate when SCC are down?
coliforms don't adhere to epithelial cells so when SCC is high, coliforms are quickly eliminated
do coliform infections proliferate during milking or dry periods? are they clinical or subclinical?
establish during late dry period (no "flushing effect") - subclinical then flare up after calving/during immunocompromise
how does coliform mastitis become endotoxemia?
- multiply then die in gland - release endotoxin from cell wall
- TNF-alpha released by body and triggers cascade - hematogenous spread
what are the most important inflammatory cytokines involved in endotoxemia? what is the main problem caused by these mediators?
- IL1, 6 and TNF-alpha
- increased vascular permeability
do most cows with coliform mastitis recover spontaneously or die?
- most recover spontaneously w/o treatment
- (unless endotoxemia then death)
how does milk appear with coliform mastitis? what will udder look like?
- egg drop soup (serous fluid replaces milk)
- acute swelling of gland
why are cows with endotoxemia polyuric?
altered response to ADH so pee alot even though hypovolemic
Assuming the cow recovers from coliform mastitis, what is the result to the udder?
- will not be able to milk for remaining lactation but will return to normal after next calving
- good news: environmental/coliform mastitis will NOT cause permanent fibrosis like contagious/staph will
are systemic antibiotics indicated for coliform mastitis?
- yes, to prevent pneumonia and endocarditis
- intramammary can be troublesome bc should be stripping udder every 4-6 hours
Is the vaccine for coliform mastitis recommended? As prevention or to reduce severity?
- effective to *reduce severity*
- labor intensive, requires multiple injections (3 given 3 weeks apart)
what is the most common isolate in heifers and beef cows for mastitis? what is the cause?
- staph aureus - flies transmit
- (gangrenous more in heifers than old)
what is most common isolate in small ruminants with mastitis?
- staph aureus - gangrenous
- (suspect mycoplasma mycoides if negative culture)
what is cause of hard udder with no change in milk in small ruminants?
- CAE (caprine arthritis encephalitis)
- OPP (ovine progressive pneumonia)
what is the cause of mastitis in camelids? why is it more difficult to treat them intramammary?
- rare in camelids
- each quarter has 2 distinct lobes - tom cat catheter
what is the problem with udder edema?
- extra weight - pendulous - harder to attach equipment and more prone to trauma
- (milk remains normal; udder should NOT be hot)
when is blood in the milk seen but not a problem?
when are we worried about it?
- Pink after calving= No problem
- Bloody= Problem= Severe mastitis
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