Exam 2: Mammary Gland Flashcards by Preeti Gulve

Herd average milk production for Holstein cows in

US corn silage based systems is _______ lbs per day

65‐85lbs

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

100‐140 lbs

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

quart

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

one

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The _________ is the most important support structure

and supports and separates the two lateral halves of the udder

median suspensory ligament

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There is no _________of the duct system between quarters

no crossover

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The front teats are usually a little _____than the rear teats

larger

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Teat skin condition, teat end condition and the

_______lining of the streak canal are important factors

in protection against new intra‐mammary infections.

keratin

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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).

Mycoplasma mastitis

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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.

secretory parenchyma

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

100‐400 ml

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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.

allometric

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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

Allometric growth period

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

Growth hormone

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

oxytocin

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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

milk let‐ down time

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

Oxytocin

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

teat canal

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

somatic

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Antibody levels in milk are much ________than those in plasma

lower

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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.

coliform (E.coli)

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What 3 organisms can cause contagious mastitis?

Staphylococcus aureus*
Streptococcus agalactiae*
Mycoplasma bovis*

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Mastitis infections are transferred from

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

teat‐end impacts

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

Contagious

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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.

Streptococcus agalactiae (contagious mastitis)

T/F: Streptococcus agalactiae infections penetrate deeply into the mammary stroma

FALSE

T/F: *streptococcus agalactiae* is commonly resistant to antibiotics

FALSE

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

rapidly expanding

Once Streptococcus agalactiae was controlled \_\_\_\_\_\_\_\_became the most important cause of contagious mastitis.

Staph aureus

Staph aureus causes subclinical and clinical mastitis. Some strains cause an acute _______ mastitis which can result in sloughing of the affected quarter.

gangrenous

The virulence factor for _____ has the ability to penetrate into tissue, forming micro‐abscesses which the cow walls off

Staph aureus

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

Staphylococcus aureus

Some strains of S. aureus are resistant to \_\_\_\_\_\_\_antibiotics

beta‐lactam

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

Mycoplasma bovis

\_\_\_\_\_\_is the only mastitis organism of cattle that spreads hematogenously.

Mycoplasma

A history of respiratory disease or ear infection in calves occasionally precedes outbreaks of ______ mastitis.

Mycoplasma

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

*Mycoplasma bovis*

How is Mycoplasma bovis mastitis controlled?

CULLING infected cows

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.

Streptococcus uberis and Streptococcus dysgalactiae (environmental mastitis)

Many infections by Streptococcus uberis and Streptococcus dysgalactiae self‐cure in about _______ days

8 days

The most important virulence factor of Streptococcus. uberis and Streptococcus dysgalactiae are their ability to resist _______ by PMNs

phagocytosis

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

straw

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

Penicillins Pirlimycin Cephalosporins

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

oxytocin

List the coliform bacteria that cause mastitis

**E. coli** **Klebsiella** **Enterobacter** Serratia, Pseudomonas, Proteus

Coliform bacteria are \_\_\_\_\_\_\_organisms and are ubiquitous in the environment

opportunist

In herds with very low somatic cell counts most clinical mastitis cases are caused by \_\_\_\_\_\_\_\_\_\_.

coliforms

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.

endotoxin

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

SCC (Somatic Cell Counts)

Most cases of coliform mastitis occur \_\_\_\_\_\_\_in lactation.

early

High levels of _______ and \_\_\_\_\_\_\_have been associated with the use of sawdust and shavings, especially green and wet sawdust

E. coli and Klebsiella

Acute cases of this causative agent of mastitis have a swollen gland, watery milk with small flakes and mild systemic disease.

Coliforms

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

Coliforms

How is coliform mastitis treated?

Stripping of the gland to remove toxins, fluid and electrolytes (hypertonic saline i/v is commonly used so that cows rehydrate themselves), NSAIDs.

How is coliform mastitis controlled?

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.

This vaccine can be used to control/prevent coliform mastitis when given in the dry period and early lactation.

J‐5 vaccine

Coagulase negative staphylococci include these 2 agents, and are minor pathogens that rarely cause clinical mastitis

Staph. epidermidis and Staph. hyicus

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

somatic cell count

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.

Corynebacterium bovis

What are the 5 stages to the udder examination?

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.

SCC \> 200,000 in the absence of systemic disease (inflamed udder, fever, off feed, large clots in milk) indicates \_\_\_\_\_\_\_\_\_\_\_.

sub‐clinical mastitis

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

PMNs

The \_\_\_\_\_\_\_of milk is used as an indication of udder infection

somatic cell count (SCC)/ml

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

750,000/ml

. Sub‐clinical mastitis results in replacement of secretory tissue by \_\_\_\_\_\_\_\_\_\_\_\_

scar tissue and abscesses

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

Strep agalactiae, Staph aureus or the environmental streptoccci.

In herds with low SCC \<100,000 most cases of clinical mastitis are due to \_\_\_\_\_\_\_\_

Summer mastitis is most often seen in heifers and dry cows at summer pasture and is due to infection with these 2 agents

Arcanobacter pyogenes and Strep dysgalactiae

Most intramammary antibiotics available in the US are aimed at gram ______ bacteria

positive

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)

Procaine Penicillin G (4d) and Ampicillin (48h)

\_\_\_\_\_\_\_\_\_\_\_ given systemically has no milk withdrawal but also does not have bacteriocidal activity in the udder.

Ceftiofur (Naxcel, Excenel)

\_\_\_\_\_\_\_\_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

Gentamycin

\_\_\_\_\_\_\_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.

Tilmicosin (Mycotil)

Gauze soaked in this is used to clean teat ends

70% isopropyl alcohol

Udder edema can be a problem in the peri‐parturient cow, particularly in this type of cow

heifers when they have their first calf

How is severe udder edema treated?

massage, diuretics (furosemide) or corticosteroids such as dexamethasone

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.

furosemide

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

Mycoplasma

Virtually all herds are infected with this causative agent of mastitis

Staphylococcus aureus

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

Str. agalactiae

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

TRUE

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

1,000

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.

16 samples

\_\_\_\_\_\_\_\_\_is the most frequently recovered of the environmental Streps. followed by Str. dysgalactiae.

Streptococcus uberis

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

teat dipping

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.

dry cow treatment

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

S. aureus

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

Staph aureus