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do all quarters produce milk equally?
caudal 2 quarters produce 60%
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where is milk produced? what happens when mammary gland is stimulated?
- alveolar cells produce milk
- release of oxytocin - contraction of myoepithelial cells and sphincter relaxes
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what hormone inhibits oxytocin release?
catecholemines (epinephrine) - don't startle the cows at milking time
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how much blood supply is required to produce one gallon of milk?
500 gallons of blood
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what are the major hormones needed for milk production?
- ACTH and prolactin
- (also insulin, growth hormone, TSH, PTH)
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at time of calving are ACTH, prolactin, and progesterone high or low? what do these levels promote formation of?
- hi: ACTH, prolactin
- low: progesterone
- conversion of alpha-lactalbumin to *lactose*
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what are three diseases you should look for when examining the utter, as they do not have treatments, only prevention? which is contagious?
- pseudocowpox - scabs
- herpes mammilitis - crusts/open sores
- bovine papillomavirus - contagious
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how many somatic cells (WBCs) are in a healthy utter?
<100,000 cells/ml
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what cell greatly increases when fighting bacterial infection in utter? does this cell work better or worse than when fighting bacteria in the blood?
- neutrophils can get into the millions
- less effective in milk - no available glucose and fat/casein coats them
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Lactoferrins are an important defense against which pathogens? how do they work?
- coliforms (kleibsiella and e.coli)
- -bind iron so bacteria can't use it for growth
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why is post-parturiant cow more likely to develop mastitis?
- immunocompromised (high cortisol for delivery impairs immune)
- oxytocin leaves sphincter slightly open
- laying in dirty environment
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what happens in the gland when bacteria and SCC overwhelm it?
milk clot/plug with debris can lead to atrophy of alveolus
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How does a peracute mastitis differ from acute mastitis?
- both have sudden onset of signs
- peracute - systemic illness precedes abnormal milk
- acute - less severe systemic illness
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what is the difference between subacute, subclinical and chronic mastitis?
- subacute - no systemic illness; only small clots/mild inflammation
- subclinical - inflamed mammary w/NO systemic illness signs
- chronic - can be subclinical for months w/flare ups
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of all forms of mastitis, which is most common?
subclinical
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what are you looking for when using a strip cup to evaluate each quarter? will this test show anything abnormal for subclinical mastitis?
- macroscopic evaluation for color and consistency (flakes, gargot/clumps, watery, bloody)
- NO changes if cow is subclinical
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what leukocytes are present in the milk in health? in illness?
- health = macrophages
- illness = neutrophils
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will somatic cell counts reveal subclinical cases?
- what are the indirect ways to do SCC?
- yes
- indirect: estimated SCC counts
- -California mastitis test for individuals
- -Wisconsin Mastitis Test for bulk samples
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what are direct ways to do SCC?
- exact counts:
- -direct microscopic
- -electronic
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When California Mastitis Test is performed, alkyl arylsulfonate and bromcresol purple are added to the milk. What does this cause to happen?
- lysis of cells and polymerizes DNA - forms gel
- (more gel = more nucleated cells)
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What is the milk to reagent ratio for CMT? how long do you wait to determine results?
- 1:1 (don't fill cup more than half full of milk)
- read within 30sec
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if CMT gets score of trace, about how many cells are present? what if its score of 1 (distinct slime)?
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what will CMT cup look like if it gets a score of 2 vs. 3?
- 2: distinct gel (2.7x10^6)
- 3: convex gel (8.1 x10^6)
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what is the maximum allowable SCC in milk in the US?
<750,000
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what are some causes of false positive results on CMT?
- *Increased WBCs* - colostrum or trauma to udder
- *less fluid but same # WBCs* - late lactation/dry off or illness that decr. production
- *higher # than rest of milk* - first strip and residual milk
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Culture samples should be collected before starting treatment. Who should have cultures run?
new to the herd and those w/incr WBC (clinical and subclinical)
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when cleaning teats for culture collection, which teat should you prepare first? What order should you collect the sample?
- clean far then near (don't contaminate what you just cleaned!)
- collect near then far (don't contaminate clean teats)
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If the sample can't be run within 48 hours, should you throw it away and start over?
no, just freeze it until it can be run
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when is it a good idea to submit separate quarter samples for culture?
- best results but $$$
- suspect Staph aureus
- only one quarter positive on CMT
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Composite samples collect from all 4 quarters in one sterile vile and is more economical but what is the draw back?
more environmental contamination
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if bulk sample results come back positive for coliforms or strep, what could this mean other than mastitis?
- problem with pre milking procedure
- (live at teat ends - access bulk tank but not in mammary)
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what test is recommended for the DHIA (dairy herd improvement association)?
direct electronic methods for specific SCC counts
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are 90% of mastitis cases from contagious cow-cow transmission or acquired from the environment?
contagious causes like staph/strep
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what are common mastitis causing organisms found in the milk and lining epithelial cells?
- strep. agalactiea, coagulase negative
- Staph. spp. and strep. dysgalactiae
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what are common mastitis causing organisms found in the deep tissue of the gland?
- staph aureus
- strep uberis
- A. pyogenes
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what are common mastitis causing organisms found in the gland as well as other body systems?
coliforms like e. coli and kleibsiella
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what is a nonpathogenic contagious organism associated with the udder?
corynebacterium bovis
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what are the "big two" contagious pathogens of mastitis?
- staph. aureus
- strep agalactia
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what kind of mastitis does staph aureus cause (peracute/acute/chronic/subclinical)?
- most cases subclinical - major loss in production
- can lead to gangrene
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How effective is the immune system at attacking staph aureus?
- evades neutrophil phagocytosis
- capsule - resists opsonization
- leukotoxin - kills phagocytes
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what makes staph aureus mastitis difficult to treat?
- B-lactamase producer so no penicillins
- deep tissues affected
- abscesses
- gangrenous form - thrombosis - blood tinged serum
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how will cow present with clinical v. subclinical staph aureus mastitis? what about strip cup? CMT?
- subclinical: cow normal, normal strip, positive CMT
- clinical: febrile/anorexic, abnormal strip, positive CMT
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how will cow present with chronic staph aureus mastitis? strip cup?
- palpable fibrosis in udder
- abnormal milk if flare-up or can be subclinical/normal strip cup
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