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What you see in milk in mastitis
- usually <100,000 cells in milk.
- mastitis = >>250,000, >99% WBC, almost all of those are neutrophils (= pus)
- on average, infected cows have a higher somatic cell count (SCC), so we test this (decent height of both Sn and Sp)
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somatic cell count in milk
- 200,000 cells is the cutoff
- ~75% Sn, ~90% Sp
- 95% confidence interval, even in end of days in milk with multiparous cows (who have highest uninfected counts)
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Milk loss is associated with linear score
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contagious mastitis MO
Environmental mastitis MO
- contagious: strep agalactiae, staph aureus, mycoplasma
- environmental: strep, staph, coliforms
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drugs for mastitis and when to treat
- systemic ceftiofur! Could also do ampicillin, cephapirin, cloxacillin, hetacillin, penicillin, pirlimycin
- fluids: Hypertonic saline + oral fluids
- regional: moxi-mast in the quarter
- if not systemically ill, WAIT IF POSSIBLE
- saves $ on tx, prevents residues in tank, no abx resistance, sell more milk, 85% mild or moderate and delay doesn't hurt, wait and see.
- Some are sterile inflammation!
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5 ways a cow can get mastitis
- left front
- right front
- left hind
- right hind
- hematogenous spread (tiny proportion)
- 99% are bacteria, caused inflammation. Often acquire infection at beg of dry period
- KEEP THEM CLEAN. This will lower mastitis!!
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reasons cows won't benefit from abx
- choronic staph aureus
- mycoplasma
- multiple infected quarters
- damaged teats
- other serious metabolic disease
- repeated previous tx failures
- long history of chronically high SCC
- grade 1 or 2 ecoli, enterobacter, yeast
- truperella pyogenes
- culture negative (25-30%)
- SO ONLY TX: systemic e coli, strep, other staphs
- Every farm is different, it's a cow-by-cow decision. Most farmers guess, don't culture.
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reasons to pick a particular drug
- frequency of administration (label!)
- cost
- withdrawal
- availability
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up and down-sides of on-farm culturing
- up: reference lab too far away
- down: can't detect mycoplasma, prototheca difficult, staph aureus false positive risk, protocol drift, equipment maintenance and inventory, opportunity cost of valuable people's time (only a few people who are good at it)
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ups and downs of reference lab diagnostics
- ups: experts do the work, ALL pathogens ID'd, quality control is daily, no maintenance or inventory, only training to take samples. $5.50
- downs: too far from lab, rely on someone else
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Bulk tank SCC count
- done on composite bulk talk sample
- multiple times/month
- legal limit is 750,000 but no one takes over 400,000
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***New infections are common in what stages of lactation?
Calving and dry off
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