Exam 2: Mammary Gland Flashcards
Herd average milk production for Holstein cows in
US corn silage based systems is _______ lbs per day
65‐85lbs
At the peak of lactation cows may produce ______ lbs of milk per day
100‐140 lbs
During milking up to a ______of milk/minute passes through each teat end.
quart
The cow has _____ udder(s) and four quarters!
one
The _________ is the most important support structure
and supports and separates the two lateral halves of the udder
median suspensory ligament
There is no _________of the duct system between quarters
no crossover
The front teats are usually a little _____than the rear teats
larger
Teat skin condition, teat end condition and the
_______lining of the streak canal are important factors
in protection against new intra‐mammary infections.
keratin
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
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
Milk available in the cisterns between milkings amounts to _____ mL in each quarter
100‐400 ml
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
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
___________is the predominant hormone governing synthesis of milk in cattle (vs. prolactin in non‐ ruminants)
Growth hormone
Milk ejection (as opposed to milk synthesis) is under the influence of the pituitary hormone _______.
oxytocin
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
_______secretion is triggered by stimulation of the mammary gland and teats, and also by other situational triggers, such as entering the milking parlor
Oxytocin
The _______is the main barrier to infection entering the tissues of the udder
teat canal
Polymorphonuclear leucocytes (known as ______cells) constitute the major cellular response to bacterial infection in the udder, but do not trigger immune memory.
somatic
Antibody levels in milk are much ________than those in plasma
lower
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)
What 3 organisms can cause contagious mastitis?
- Staphylococcus aureus*
- Streptococcus agalactiae*
- Mycoplasma bovis*
Mastitis infections are transferred from
teat to teat by ______ (blow‐back of milk droplets into the teat end)
teat‐end impacts
________mastitis is transmitted during the milking process as a result of contamination of milking equipment with milk containing mastitis bacteria
Contagious
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?
- Visual exam
- Palpation of udders (deep and superficial)
- Examine milk with strip cup
- Use California Mastitis Test (CMT) to detect subclinical mastitis
- 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
