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Prevention & Production Medicine > Milk Quality and Mastitis Control > Flashcards

Milk Quality and Mastitis Control Flashcards

1
Q

True or False: pathogens are able to move easily between the quarters of the udder

A

false; these are separated by connective tissue

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2
Q

What type of cells synthesize and secrete milk?

A

alveolar cells; 60% milk storage

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3
Q

Milk letdown is induced by what?

A

oxytocin-induced contraction of myoepithelial cells

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4
Q

Following milk letdown, the milk is transported to where?

A

gland cistern via ducts (ducts = 20% milk storage)

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5
Q

Milk is accumulated in where?

A

the gland cistern (cistern = 20% milk storage)

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6
Q

What is the physiology of milk letdown?

A

suckling stimulates release of oxytocin > induces milk letdown; this “suckling” is more commonly stimulated by workers

  • oxytocin has a very short half life: 2-3 minutes
  • milk letdown is inhibited by stress
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7
Q

If milk letdown does not occur, what is the issue with this?

A

60% of the milk is stored in the alveolar cells, so only 40% of the milk produced will be readily accessible without milk letdown

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8
Q

What are the various methods of teat protection?

A
  • skin
  • inner and outer sphincters
  • keratin plug
    • physical barrier
    • bacteriostatic properties
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9
Q

What makes up the innate immunity of the bovine udder?

A
  • macrophages
  • neutrophils
  • NK cells
  • complement
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10
Q

What are somatic cells and what levels of somatic cells are diagnostic for disease.

A
  • immune cells that move from blood into the mammary gland
  • Healthy and non-infected glands: SCC < 100,000 cells/mL of milk
    • mostly macrophages, neutrophils, lymphocytes, and epithelial cells
  • Infected glands: SCC > 200,000 cells/mL of milk
    • mostly neutrophils
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11
Q

What is mastitis and what are signs of peracute mastitis?

A

= inflammation within the mammary gland

  • Peracute
    • 5 cardinal signs (redness, heat, swelling, pain, loss of function)
    • Systemic signs (fever, anorexia, dehydration, depression, muscle tremors, “down cow”)
    • Fast progression (4-12 hrs) and death
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12
Q

What are the signs of acute mastitis?

A
  • 5 cardinal signs: redness, heat, swelling, pain, loss of function
  • mild depression and fever
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13
Q

What are the signs of subacute mastitis?

A
  • subdued signs of inflammation
  • most common presentation of clinical mastitis
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14
Q

What are signs of subclinical mastitis?

A
  • inflammation in the absence of gross signs (incr SCC)
  • most common presentation of mastitis
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15
Q

What are signs of chronic mastitis?

A
  • persistence of inflammation for weeks/months
  • continuous process or periodic flare-up cases
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16
Q

What pathogens are most commonly associated with mastitis?

A

most commonly caused by bacterial intramammary infection (IMI); fungi/yeast = least common

  • Contagious pathogens:
    • cow-to-cow trasmission via fomites
      • Strep agalactiae
      • Staph aureus
      • Mycoplasma sp.
  • Environmental:
    • Strep uberis
    • Strep dysgalactia
    • Coagulase neg. Staph. (CNS)
    • Trueperella pyogenes
    • Coliforms
      • E. coli, Klebsiela sp., Serratia sp., Pseudomonas sp.
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17
Q

Describe the MOA of Staph aureus in causing mastitis

A
  • causes moderate incr in SCC
  • small shedding in milk
  • inflammation mediated by coagulases, alpha, beta, and epsilon-hemolysins
  • beta-lactamase and deep penetration into tissue: poor response to tx
    • consider segregation and culling
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18
Q

What is the MOA of Strep agalactiae in causing mastitis?

A
  • does not actively invade parenchymal tissue
  • inflammation is mostly subclinical w/ acute flare-ups
  • blockage of collecting ducts
  • leads to involution of mammary tissue
    • replacement of secretory cells w/ scar tissue
    • decr milk production
  • marked incr in SCC
  • Abx susceptibility
    • ampicillin, cephapirin, pirlimycin
19
Q

What is the MOA of Mycoplasma sp. in causing mastitis?

A
  • inflammation is often subclinical w/ acute flare-ups
  • clinical cases often progress from 1 to mult quarters b/t 1-3 d
    • coffee-grounds appearance to milk
  • intro via purchase of diary animals or intro of outside rearing heifers
    • biosecurity
  • non-responsive to antimicrobial tx
    • ID and culling
    • segregation challenge
      • need for specialized culture (4-7d for lab results)
20
Q

What is the MOA of Strep uberis in causing mastitis?

A
  • acute and chronic mastitis (similar to Strep agalactiae)
21
Q

What is the MOA of Strep dysgalactiae in causing mastitis?

A
  • infections assoc. w/ teat injury (viral, mechanical, chemical, etc.)
22
Q

What is the MOA of coliforms in causing mastitis?

A
  • peracute to acute mastitis
    • sudden and marked swelling of affected quarter
    • fever, mm tremors, rumen stasis, dehydration
    • serous milk (early) w/ fibrin or pus (late)
  • incr incidence of death and agalactia compared w/ other pathogens
    • px particularly guarded for Klebsiella sp.
  • Fast recovery if inflamma contains pathogen proliferation
    • milk production recovered in 1-2 weeks
23
Q

Why is early lactation a high risk period for developing mastitis?

A
  • immunosuppression occurs during early lactation (3-4 wks postpartum)
    • stress and cortisol concentrations around parturition
    • negative nutrient balance
    • oxidative stress
24
Q

What is the impact of elevated milk production around peak lactation?

A

loss of teat canal integrity and milk leakage

25
Q

What are some reasons that first 21 days of the dry off period (i.e. involution) is a time of increased susceptibiltiy to new IMIs?

A
  • pressure from milk buildup (production declines and cows are not milked)
  • potential milk leakage w/o constant teat end disinfection
  • death of secretory cells and active tissue remodeling
  • failure to form keratin plug
26
Q

What are some reasons that last 7-14 days of the dry off period (i.e. involution) is a time of increased susceptibiltiy to new IMIs?

A
  • pressure from colostrogenesis
  • decr lactoferrin and resident leukocytes
  • colostrum components impair function of immune cells
  • rapid tissue differentiation and oxidative stress
27
Q

What are the best ways to prevent IMIs during the dry off period?

A
  • health management - biosecurity
    • segregation and culling of chronically infected cows
  • nutrition
  • cow comfort - clean and dry environment
  • vaccination
  • teat skin condition
    • excellent milking procedures
  • improve immunity peripartum
28
Q

What are the goal and objectives of milk parlors and machine milking?

A

Goal: milk cows quickly, gently, and completely

  • incr milk harvested
  • decr discomfort of cows
  • decr risk of injury and mastitis
29
Q

What steps are a part of the cleaning and stimulation process in milk parlors?

A
  • apply disinfectant (pre-dip)
  • remove foremilk (cistern)
    • 2-3 strings from each quarter
    • 15 sec per cow
    • check for mastitis
      • clean/black floor
      • mastitic milk cannot go to bulk tank
  • dip-strip vs. strip-dip vs. dip-strip-dip
30
Q

What steps are a part of the contact time for disinfection process in milk parlors?

A
  • 30 seconds
  • proper udder preparation removes 75% of bacteria present on teat skin to attachment
  • bacteria left on teat will end up in milk
  • past 30 seconds:
    • strip and wipe teats with a single-use towel (teat and teat end)
31
Q

What is the purpose of the lag time in milk parlor procedings and how long should this be?

A
  • allows cow to respond to manual stimulation
  • 70-80 sec
32
Q

What steps are a part of attaching the cow’s udder to the milking machine?

A
  • 90-120 sec after onset of manual stimulation
  • goal is to attach unti to clean/dry teats
    • ​prevents liner slips
  • attention to placement of claw
    • folded teats
    • dry quarters
33
Q

Describe the process of milking the cow with the milking machine

A
  • 4-6 min
  • machine maintenance
    • proper pulstor fxn
    • adequate vaccum presure
  • fix liner slips
    • backflow of milk, potential for contamination
  • avoid over-milking
    • residual milk (50-100 mL/quarter)
34
Q

What are the steps in detaching the cow from the milking machine and the post-dip?

A
  • cut-off vaccum
    • avoid teat injury
  • automatic based on milk flow
35
Q

After milking, cows will return to a …

A
  • clean and dry pen
  • fresh food and water
  • proper heat abatement
36
Q

What are the various severity scoring levels for mastitis?

A
  1. Mild = abnormal milk (clots, flakes, watery)
  2. Moderate = abnormal milk + signs of udder inflammation (heat, swelling, pain)
  3. Severe = systemic illness (fever, dehydration, wekaness, inappetence)

*tx based on severity: intramammary abx, +/- anti-inflammatory, +/- systemic and supprortive tx

37
Q

What are your treatment considerations and diagnostics for chronic cases of mastitis?

A
  • “three strikes rule” - do not tx quarter > 3x within a lactation
  • > 2 monthly tests with SCC > 200,000 cells/mL
  • consider non-tx options:
    • older cows
    • other dz
    • mult quarters
    • culling cow
    • early dry-off
38
Q

What are your options for diagnosing specific mastitis pathogens?

A
  • lab tests: 24-48hrs, except Mycoplasma = 7d
  • on-farm culture: improve timing
    • UMN bi- and tri-plate
    • chromogenic selective media
39
Q

How do you decide to treat based off your culture results?

A
  • no growth - do not tx
    • gram - cleared by time of culture
    • Mycoplasma
  • gram - = do not tx
    • robust immune response
    • incr spontaneous cure
  • gram + = treat
    • ​less robust immune response (decr spontaneous cure)
40
Q

What are the cure rates for various IMI pathogens?

A
  • Strep agalactiae - 90-95%
  • CNS - 60-80%
  • Environmental Strep - 40-50%
  • Staph aureus - 20-30%
41
Q

What are your monitoring parameters for herds and mastitis?

A
  • bulk milk SCC and bacterial counts
  • rate of clinical mastitis
  • prevalence of subclinical mastitis
  • presence of contagious mastitis pathogens
42
Q

What is the protocol for dry cow therapy?

A
  • treat all quarters from all cows with long-acting intramammary abx at dry off
    • +/- teat sealants
    • particularly important for S. agalactiae and S. aureus
  • Goal: minimize new infections and promote cure during dry period
  • Vaccination:
    • coliform mastitis (E. coli): reduces CS
    • Klebsiella sp. mastitis: under dev.
43
Q

What are the 6 keys to a mastitis control program?

A
  1. Proper milking management
  2. Environmental control
  3. Dry cow therapy
  4. Milking machine maintenance
  5. Treatment protocols
  6. Vaccination

Prevention & Production Medicine (17 decks)

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