L4: Bovine Mastitis and Prod. Quality Milk (Donovan)

Question 1

fx of alveoli in mammary gland

Answer 1

• milk synthesis

- oxytocin responsive smooth m.

Question 2

1st and most important line of defense against invasion by pathogenic bact.

Answer 2

teat canal

-lined by smooth m, squamous epithelium, and thick layer of keratin that is bacteriostatic

Question 3

inflamm. char. by 5 signs

Answer 3

heat
pain
redness
swelling
disturbed function

Question 4

clinical forms of mastitis

Answer 4

peracute (most severe)
acute
subacute (most common CLINICAL form)
subclinical (most common form!)
chronic

Question 5

peracute mastitis

Answer 5

• most severe form
• CS in 4-12hr
• local AND systemic sign (fever, anorexia, dehydration, depression, m. tremor, +/- d)
• death common

Question 6

acute mastitis

Answer 6

• 5 signs of inflamm. present

- usually accompanied by mild depression, fever

Question 7

subacute mastitis

Answer 7

• subdued inflamm. signs
• not systemic
• most common CLINICAL form

Question 8

subclinical mastitis

Answer 8

• inflamm. w/o gross signs
• testing needed to detect
• most common form of mastitis!

Question 9

chronic mastitis

Answer 9

• inflamm. over wks/mos or from 1 lactation to the next

- continuous or periodic flare-ups that prod. acute or subacute CS

Question 10

major primary udder pathogens causing mastitis

Answer 10

S. aures
Strep agalactiae
Mycoplasma sp.
Strep dysgalactia

Question 11

major env. pathogens causing mastitis

Answer 11

strep uberis

strep dysgalactia

Question 12

minor env. pathogens causing mastitis

Answer 12

Staph coag neg
coliforms
A. pyogenes

Question 13

pathogenesis of Strep agalactiae

Answer 13

• does NOT actively invade tissue
• irritant accumulates and intensifies inflamm. rxn
• replacement of secretory tissue w/ scar tissue
• atrophy of mammary gland
• dec. milk prod. with very inc. bacterial/SC counts in milk

Question 14

control of strep ag***

Answer 14

• can be eradicated!
• post-dipping
• dry cow therapy
• ID infected cows and treat (Blitz treatment
• Blitx treatment (abx during lactation) –> 90% reduction in 1/4 infection rate***

Question 15

T/F: Blitz tx ONLY works for Strep ag mastitis***

Answer 15

T

Question 16

S. aureus

Answer 16

• causes contagious mastitis**
• usually subclinical and chronic
• micro-abscess w/n gland
• peracute form –> gangrene
• reservoirs = milk, teat skin
• causes mod. inc. in SCC

Question 17

path. of S. aureus

Answer 17

• penetrates into tissue
• prod. toxins (ie. alpha hemolysin assoc. with gangrenous mastitis)
• produces penicillinase
• abx have hard time penetrating CT of abscesses

Question 18

mycoplasma sp.

Answer 18

• causes contagious mastitis**
• pneumonia, otitis, arthritis in calves
• often subclinical
• coffee-grounds appearance to milk
• non-responsive to abx
• periodic shedding
• primarily a RESPIRATORY pathogen

Question 19

strep uberis and dysgalactia

Answer 19

• ENVIRONMENTAL
• NOT susceptible to eradication
• opportunistic
• uberis –> acute and chronic mastitis indistinguishable from Strep ag
• dysgalactia –> infections usually follow teat injury and enhanced by teat lesions

Question 20

95% rule

Answer 20

95% of all mastitis due to:
strep ag
staph aureus
strep uberis
strep dysgalactia
coliforms

Question 21

coliforms

Answer 21

• ENVIRONMENTAL
• opportunistic
• low numbers of bact. shed in milk
• causes peracute to acute mastitis
• herds with low SCC may be at inc. risk

Question 22

coliform mastitis char. by

Answer 22

• sudden marked swelling of quarter
• fever, m. tremor, rumen stasis, dehydration +/- d
• udder secretion serous –> thick with fibrin/leukocytes

Question 23

pathogenesis of coliforms

Answer 23

• non-invasive
• endotoxins** released from bacteria when destroyed by immune system
• recovery usually rapid
• usually not chronic

Question 24

goal % clinical cases

Answer 24

<3% of milking cows with clinical mastitis/month

Question 25

California mastitis test

Answer 25

indirect measure of somatic cells in milk - screens for subclinical mastitis - not good for differentiating b/w infected and non-infected cows

Question 26

relationship b/w SCC and milk prod. loss

Answer 26

linear (inc. SCC --> inc. milk loss)

Question 27

components of mastitis control program

Answer 27

``` Proper milking management env. control dry cow therapy milking machine maintenance treatment protocols vaccination ```

Question 28

pre-milking management

Answer 28

- clean and dry teats - preDIP (controls env. mastitis) - STRIP - WIPE - HANG

Question 29

milking management

Answer 29

- avoid linear slips (can contribute to inc. coliform units) - milk cows with DRY teats only!! - readjust machine if necessary - don't overmilk

Question 30

post-milking management

Answer 30

- make sure cow is milked out - dip all 4 teats on all cows - send cow to feedbunk with fresh feed and water

Question 31

when does highest incidence of infection occur?

Answer 31

drying off period (2nd most common = after calving)

Question 32

Dry Cow Therapy

Answer 32

-all functional quarters of all cows should be treated w/ long-acting intramammary abx at time of drying off, esp. for control of strep ag, staph aureus

Question 33

T/F: culling is a form of tx

Answer 33

T

Question 34

recommended and non-recommended vax

Answer 34

rec: E. coli | not rec: Staph aureus, Mycoplasma bovis