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RUSVM LAM II Practice Questions > Exam 2: Mammary Gland > Flashcards

Exam 2: Mammary Gland Flashcards

1
Q

Herd average milk production for Holstein cows in

US corn silage based systems is _______ lbs per day

A

65‐85lbs

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2
Q

At the peak of lactation cows may produce ______ lbs of milk per day

A

100‐140 lbs

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3
Q

During milking up to a ______of milk/minute passes through each teat end.

A

quart

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4
Q

The cow has _____ udder(s) and four quarters!

A

one

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5
Q

The _________ is the most important support structure

and supports and separates the two lateral halves of the udder

A

median suspensory ligament

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6
Q

There is no _________of the duct system between quarters

A

no crossover

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7
Q

The front teats are usually a little _____than the rear teats

A

larger

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8
Q

Teat skin condition, teat end condition and the

_______lining of the streak canal are important factors

in protection against new intra‐mammary infections.

A

keratin

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9
Q

With the exception of some ________infections, which may be seeded into mammary tissue by hematogenous spread,

all mastitis causing bacteria enter through the teat canal (streak canal).

A

Mycoplasma mastitis

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10
Q

The internal structures of the udder include the

__________consisting of grape‐like clusters of myo‐epithelial alveolar tissue

which express milk under the influence of oxytocin,

the ducts which lead from the secretory tissue,

and the cisterns, including the gland cistern, which opens into the teat cistern.

A

secretory parenchyma

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11
Q

Milk available in the cisterns between milkings amounts to _____ mL in each quarter

A

100‐400 ml

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12
Q

Mammary tissue develops in the udder at an accelerated rate compared to the tissues of the rest of the body between about 3 months of age and puberty (9 ‐ 11 months).

This is known as the period of _______ growth.

A

allometric

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13
Q

Underfeeding in this period impairs udder development.

More importantly, overfeeding during this period can lead to the

deposition of excess fat in the udder and

reduce milk secretion capacity in adult life

A

Allometric growth period

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14
Q

___________is the predominant hormone governing synthesis of milk in cattle (vs. prolactin in non‐ ruminants)

A

Growth hormone

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15
Q

Milk ejection (as opposed to milk synthesis) is under the influence of the pituitary hormone _______.

A

oxytocin

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16
Q

The delay between oxytocin secretion from the pituitary gland and

ejection of milk in the mammary gland

is between 60 and 90 seconds.

This is known as the _______ time

A

milk let‐ down time

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17
Q

_______secretion is triggered by stimulation of the mammary gland and teats, and also by other situational triggers, such as entering the milking parlor

A

Oxytocin

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18
Q

The _______is the main barrier to infection entering the tissues of the udder

A

teat canal

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19
Q

Polymorphonuclear leucocytes (known as ______cells) constitute the major cellular response to bacterial infection in the udder, but do not trigger immune memory.

A

somatic

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20
Q

Antibody levels in milk are much ________than those in plasma

A

lower

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21
Q

Although there is an effective vaccine against _____mastitis,

no effective vaccines have been produced

against the other major mastitis pathogens including

environmental streptococci, Streptococcus agalactiae, Staphylococcus aureus and Mycoplasma bovis.

A

coliform (E.coli)

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22
Q

What 3 organisms can cause contagious mastitis?

A
  • Staphylococcus aureus*
  • Streptococcus agalactiae*
  • Mycoplasma bovis*
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23
Q

Mastitis infections are transferred from

teat to teat by ______ (blow‐back of milk droplets into the teat end)

A

teat‐end impacts

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24
Q

________mastitis is transmitted during the milking process as a result of contamination of milking equipment with milk containing mastitis bacteria

A

Contagious

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25
Q

This used to be the most prevalent contagious mastitis organism. The Five Point Mastitis Control Program was introduced in the 1960’s to control this infection, primarily because of its negative impact on cheese yield.

A

Streptococcus agalactiae (contagious mastitis)

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26
Q

T/F:

Streptococcus agalactiae infections

penetrate deeply into the mammary stroma

A

FALSE

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27
Q

T/F:

streptococcus agalactiae is commonly resistant to antibiotics

A

FALSE

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28
Q

Recently there has been a resurgence of Streptococcus agalactiae infections because of the movement of infected cattle into _______ herds.

A

rapidly expanding

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29
Q

Once Streptococcus agalactiae was controlled

________became the most important cause of contagious mastitis.

A

Staph aureus

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30
Q

Staph aureus causes subclinical and clinical mastitis.

Some strains cause an acute _______ mastitis which can result in sloughing of the affected quarter.

A

gangrenous

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31
Q

The virulence factor for _____ has the ability to penetrate into tissue,

forming micro‐abscesses which the cow walls off

A

Staph aureus

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32
Q

Shedding of this bacteria is intermittent, so milk cultures do not always show the presence of infection

A

Staphylococcus aureus

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33
Q

Some strains of S. aureus are resistant to _______antibiotics

A

beta‐lactam

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34
Q

New udder infections can also arise when _______,

which is a common inhabitant of the respiratory tract of cattle,

spreads from the respiratory system to the udder

A

Mycoplasma bovis

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35
Q

______is the only mastitis organism of cattle that spreads hematogenously.

A

Mycoplasma

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36
Q

A history of respiratory disease or ear infection in calves

occasionally precedes outbreaks of ______ mastitis.

A

Mycoplasma

37
Q

Which causative agent of mastitis in cattle results in the following:

Multiple quarters infected

Dramatic drop in milk production

Cows appear healthy apart from severe mastitis

Unresponsive to antibiotic treatment

Milk has flakes in it, and the milk is often watery

A

Mycoplasma bovis

38
Q

How is Mycoplasma bovis mastitis controlled?

A

CULLING infected cows

39
Q

These 2 mastitis agents are the most common pathogens isolated

from high SCC cows and clinical cases in herds

in which contagious mastitis is under control.

A

Streptococcus uberis and

Streptococcus dysgalactiae

(environmental mastitis)

40
Q

Many infections by Streptococcus uberis and Streptococcus dysgalactiae

self‐cure in about _______ days

A

8 days

41
Q

The most important virulence factor of

Streptococcus. uberis and Streptococcus dysgalactiae

are their ability to resist _______ by PMNs

A

phagocytosis

42
Q

High levels of environmental streps. are found in bedding, particularly ____.

A

straw

43
Q

Str. uberis and Str. dysgalactiae infections respond well to these antibiotics

A

Penicillins

Pirlimycin

Cephalosporins

44
Q

Many environmental streptococcus infections spontaneously cure in two to 3 milkings with milking out and adjunct ______ treatment.

A

oxytocin

45
Q

List the coliform bacteria that cause mastitis

A

E. coli

Klebsiella

Enterobacter

Serratia, Pseudomonas, Proteus

46
Q

Coliform bacteria are _______organisms and are ubiquitous in the environment

A

opportunist

47
Q

In herds with very low somatic cell counts

most clinical mastitis cases are caused by __________.

A

coliforms

48
Q

When acute coliform mastitis occurs the coliform bacteria grow to very large numbers in the mammary gland and then

die off releasing large amounts of _______,

which is responsible for most of the clinical manifestations of disease.

A

endotoxin

49
Q

Coliforms rarely establish persistent infections and are not responsible for persistently elevated __________

A

SCC (Somatic Cell Counts)

50
Q

Most cases of coliform mastitis occur _______in lactation.

A

early

51
Q

High levels of _______ and _______have been associated with

the use of sawdust and shavings, especially green and wet sawdust

A

E. coli and Klebsiella

52
Q

Acute cases of this causative agent of mastitis

have a swollen gland, watery milk with small flakes and mild systemic disease.

A

Coliforms

53
Q

Peracute cases of this causative agent of mastitis

have rapid onset of severe toxemia, fever, tachycardia and impending shock.

Cow may be recumbent

(always check the udder of post‐partum downer cows for mastitis!).

Quarter may or may not be swollen.

Milk is usually thin and serous with very small flakes

A

Coliforms

54
Q

How is coliform mastitis treated?

A

Stripping of the gland to remove toxins,

fluid and electrolytes

(hypertonic saline i/v is commonly used so that cows rehydrate themselves),

NSAIDs.

55
Q

How is coliform mastitis controlled?

A

Improving the environment,

substituting sand bedding for organic materials,

keeping cows clean,

use of a pre‐dip in the milking routine,

avoid spraying the udder with water,

barrier post‐dips,

J‐5 vaccine in the dry period and early lactation.

56
Q

This vaccine can be used to control/prevent

coliform mastitis when given

in the dry period and early lactation.

A

J‐5 vaccine

57
Q

Coagulase negative staphylococci include

these 2 agents, and are minor pathogens that rarely cause clinical mastitis

A

Staph. epidermidis and Staph. hyicus

58
Q

Minor pathogens, like coagulase negative staphylococci

(particularly S. epidermidis and S. hyicus) and

Corynebacterium bovis

are usually only responsible for mild increases in _______,

and do not cause clinical mastitis

A

somatic cell count

59
Q

The presence of minor pathogens (especially _____)

is generally thought to increase resistance to colonization

by the major mastitis pathogens and thus exert a protective effect.

A

Corynebacterium bovis

60
Q

What are the 5 stages to the udder examination?

A
  1. Visual exam
  2. Palpation of udders (deep and superficial)
  3. Examine milk with strip cup
  4. Use California Mastitis Test (CMT) to detect subclinical mastitis
  5. Take Milk sample for bacteriological culture and antibiotic sensitivity.
61
Q

SCC > 200,000 in the absence of systemic disease

(inflamed udder, fever, off feed, large clots in milk) indicates ___________.

A

sub‐clinical mastitis

62
Q

_______ are attracted into the mammary gland when bacterial infection occurs. These are known as somatic cells.

A

PMNs

63
Q

The _______of milk is used as an indication of udder infection

A

somatic cell count (SCC)/ml

64
Q

In the US the Pasteurized Milk Ordinance (PMO)

says that the maximum BTSCC (bulk tank somatic cell count)

for milk to be sold as Grade A milk (i.e. for fluid consumption)

is ________/mL of milk

A

750,000/ml

65
Q

. Sub‐clinical mastitis results in replacement of secretory tissue

by ____________

A

scar tissue and abscesses

66
Q

Most sub‐clinical mastitis is caused by persistent infection with organisms such as:

A

Strep agalactiae,

Staph aureus

or the

environmental streptoccci.

67
Q

In herds with low SCC <100,000 most cases of clinical mastitis

are due to ________

A
68
Q

Summer mastitis is most often seen in heifers and dry cows at summer pasture

and is due to infection with

these 2 agents

A

Arcanobacter pyogenes and Strep dysgalactiae

69
Q

Most intramammary antibiotics available in the US are aimed at

gram ______ bacteria

A

positive

70
Q

Systemic antibiotics should not be used unless the cow is systemically sick.

Common antibiotics used are _______(4 day milk withdrawal),

and ______(e.g. Polyflex – 48 hour milk withdrawal)

A

Procaine Penicillin G (4d)

and

Ampicillin (48h)

71
Q

___________ given systemically has no milk withdrawal

but also does not have bacteriocidal activity in the udder.

A

Ceftiofur (Naxcel, Excenel)

72
Q

________should never be used in cattle –

although the recommended milk withdrawal is 10 days, there is no defined withdrawal period for meat.

It may bind to kidney tissue for 6 – 18 months

A

Gentamycin

73
Q

_______has been used extra label to treat chronic S.aureus cases at dry off.

Note that if used in lactating cattle the milk withdrawal time is at least 15 days.

A

Tilmicosin (Mycotil)

74
Q

Gauze soaked in this is used to clean teat ends

A

70% isopropyl alcohol

75
Q

Udder edema can be a problem in the peri‐parturient cow,

particularly in this type of cow

A

heifers when they have their first calf

76
Q

How is severe udder edema treated?

A

massage, diuretics (furosemide) or corticosteroids such as dexamethasone

77
Q

In the treatment of udder edema, watch out for excessive urinary losses of calcium

when giving repeated doses of _______to the older cow around the time of calving,

as this may precipitate clinical hypocalcemia.

A

furosemide

78
Q

Growth of ______requires special conditions, and culturing for this organism must be specifically requested. It will not show up during routine bacterial cultures.

A

Mycoplasma

79
Q

Virtually all herds are infected with this causative agent of mastitis

A

Staphylococcus aureus

80
Q

In the case of ________however, bulk tank culturing will efficiently identify the introduction of infected cows in to the herd.

A

Str. agalactiae

81
Q

T/F:

Bulk tank cultures as a diagnostic tool or monitor for Mycoplasma infection is sensitive and accurate.

A

TRUE

82
Q

Bulk tank cultures for Mycoplasma can detect up to one infected cow in _____

A

1,000

83
Q

In most herds the culture results from _____samples

will give a clear pattern of infection,

and will determine whether management needs to be modified to improve

control of environmental bacteria, contagious bacteria, or both.

A

16 samples

84
Q

_________is the most frequently recovered of the environmental Streps.

followed by Str. dysgalactiae.

A

Streptococcus uberis

85
Q

Post-milking _______is the management technique that shows greatest reduction in the number of new infections.

A

teat dipping

86
Q

After teat dipping, __________is the second most important technique for the control of contagious mastitis. All quarters of all cows should be treated with an effective intramammary antibiotic.

A

dry cow treatment

87
Q

__________infected cows that have not been cleared by treatment during the dry period are very difficult to cure and should be culled.

A

S. aureus

88
Q

This bacterium is much more invasive than Str. agalactiae and walls itself off in micro-abscesses in the udder tissue. This explains why shedding of the bacteria into the milk may be intermittent, and thus not always easy to detect

A

Staph aureus

RUSVM LAM II Practice Questions (19 decks)

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