Ch.36MammaryGlandHealthandDisorders

Question 1

Milk is produced in what response loop?

Answer 1

1. tactile stimulation of teats
2. neurohormonal reflex– pituitary gland releases oxytocin into the bloodstream
3. milk is ejected from the alveoli into the cisterns when surrounding myoepithelial cells contract after binding oxytocin
4. milk flows through the teat orific after resistance of teh teat canal is overcome

Question 2

When can the milk let down neurohormonal reflex be prevented from occurring?

Answer 2

with stimulation of the sympathetic nervous system– during period of stress or excitement inhibiting the release of oxytocin from the pituitary gland

Question 3

definition of subclinical mastitis

Answer 3

inflammatory process does not result in visible abnormalities in milk, mammary gland or cow

**leukocytosis and other soluble changes in milk occur

Question 4

Soluble factors of the innate immune system found in the mammary gland

Answer 4

complement
lactoferrin
acute phase proteins (mannose binding lectin and Creactive protein)

Question 5

Lactoferrin

Answer 5

iron binding glycoprotein produced by mammary epithelial cells and found in PMN granules

Question 6

What innate immune response prevents the multiplication of coliform bacteria?

Answer 6

lactoferrin– prevents multiplication of iron dependent microorganisms

Question 7

Name the pathogen targets to the specific TLRS
TLR-2
TLR-4
TLR-5
TLR-9

Answer 7

TLR-2: gram positive bacteria
-4: gram neg LPS
-5: bact flagellin
-9: bact DNA as CpG oligonucleotides

Question 8

The increase in immunoglobulin in milk in response to mastitis is due to

Answer 8

-local Ig production
-inc permeability of vascular endothelial cells and mammary epithelial cell tight junctions, which allows an influx of palsma Ig into milk

Question 9

Nonopsonizing immunoglobulins (igG1 and IgA) have what other beneficial effects in milk?

Answer 9

-neutralization of bacterial toxins
-agglutination of bacteria
-prevention of bacterial adherence to epithelial cells

Question 10

The incidence and severity of mastitis are greater in what period than during other periods of lactation?

Answer 10

periparturient period

Question 11

What is the SCC definition of healthy mammary gland?

Answer 11

<200,000 cells/mL

**review of SCC history of a cow is much more informative compared to a single value

Question 12

What percentage of quarters that are above a threshold of 200,000 cells/ml will be apparently bacteriologically negative?

Answer 12

10 to 25%

Question 13

In most herds, a greater proportion of what kind of bacteria cause subclinical mastitis?

Answer 13

Gram positive&raquo_space; gram negative

Question 14

Immunosuppression accompanying parturition is due to

Answer 14

-inc circulating cortisol concen== impairs neutorphil margination and recruitment
-early onset neutrophil phagocytosis
-low insulin like growth factor (IGF-1)

Question 15

What are the consequences of high levels of nonesterified fatty acids (NEFAs), which are typicaly in the post parturient period until peak lactation in cows?

Question 16

Is there evidence for supplementing for vitamin E, selenium or any other nutrient of this type above NRC guidelines?

Answer 16

No– variable results on supplementing vitamin E that inc/decrease mastitis

Question 17

Why is it important to identify subclinical mastitis cows within a herd?

Answer 17

b/c they are known to produce less milk
-they maintain as a pathogenic reservoir

Question 18

Describe the California mastitis test

Answer 18

CMT reaction is a mixture of detergent & bromocresol purpose used as an indicator of pH
–> the degree of reaction between teh detergent and DNA of cell nuclei is a measure of number of somatic cell sin milk

Question 19

What are compositional changes of milk occur as a result of inflammation that is part of the immune response to infection?

Answer 19

-INC SCC
-reduced casein
lactose and alpha lactalbumin concen
-influx of sodium & chloride
-INC plasma proteins
-INC protelytic and lipolytic activity
-INC lactoferrin concen & enzyme activities
-rise in pH

Question 20

Define clinical mastitis

Answer 20

production of visually abnormal milk, with or without secondary clinical signs

Question 21

What are examples of bacteria that shed into milk in high numbers (thus culture positive) vs bacteria that are low shedders (thus usually culture negative) in regards to mastitis?

Answer 21

high shedders: Streptococcus spp.

low shedders: S. aureus, Mycoplasma spp

Question 22

What are mechanisms of immune evasion that Staphlyococcus spp use in causing mastitis?

Answer 22

1. resists phagocytosis by neutrophils
   –>capsule- inhibits opsonization
   -surface protein (A) binds the Fc portion of host Ig
   -luekotoxin
2. biofilm formation
3. enzymes & exotoxins that damage mammary cells–> fibrosis & abscess formation

Question 23

What management factor reduces the prevalence of S. aureus compared to other herds?

Answer 23

**closed herds

–> farmers who purchase replacement heifers or lactatin gcows w/o screening animals or source herds often have herds with greater prevalence of S. aureus as compared to closed herds

Question 24

Based on surveys what are the most prevalent bacterial species associated with bovine mastitis

Answer 24

Staphylococcus chromogenes
Staphylococcus epidermididis
Staphylococcus haemolyticus
Stpahylococcus simulans

Question 25

What is the treatment of Non-aureus staphylococci (NAS)?

Answer 25

-beta-lactam based intramammary antibiotics at dry off– successful in treating subclinical mastitis

**not beneficial to treat during lactation

Question 26

Streptococcus agalactiae pathogenesis within the mammary gland

Answer 26

1. adheres to epithelial cells in mammary gland & localizes primarily to the duct

Question 27

Strep. agalactiae is best treated in what time period?

Answer 27

Early b/c superficial nature of infection results in minimal damage to milk secretory cells

chronic infections– see tissue damage, fibrosis & permaent decrease in milk prodction

Question 28

approximately 50% of mastitis caused by environmental streptococci are initiated during what period?

Answer 28

the dry period

Question 29

mastitis caused by environmental streptococci will spontaneously cure in what time period? and what percentage of infections persist for long periods?

Answer 29

–cure within 30 days

–30% of cases persist for long periods

Question 30

Define coliform bacteria

Answer 30

gram negative, rod-shaped organisms that can ferment lactose

Question 31

What coliform bacteria genera are commonly associated with bovine mastitis?

Answer 31

E. coli
Klebsiella
Enterobacter
Serratia

Question 32

What percentage of coliform mastitis cases result in the systemic signs?

Answer 32

30%

–fever, anorexia, marked drop in milk production

Question 33

The outcome of clinical mastitis caused by coliform bacteria depends on:

Answer 33

severity of case–> dep on: dose (magnitude of exposure) & ability of the cow’s immunologic response

Question 34

What is usually the source of contamination with Serratia species mastitis?

Answer 34

infected chlorhexidine teat cups

Question 35

What are risk factors for development of Mycoplasma mastitis?

Answer 35

-commingling of cattle from multiple herds
-off-site rearing of calves
-stressors, such as overcrowding
-nonhygienic milking practices
-insufficient biosecurity programs

Question 36

asymptomatic carriers of mycoplasma spp may infect herdmates by shedding organisms where

Answer 36

-nasal or vaginal secretions
-feces
-milk-infected semen

Question 37

Describe Prototheca spp

Answer 37

unicellular algae that are widespread in nature and occur throughout the world in habitats that contain moisture and organic matter

Question 38

What are risk factors for the development of Prototheca mastitis?

Answer 38

-use of intrammary sealants at dry off
-use of nonapproved products for intrammary infusions

Question 39

Treatment of prototheca mastitis?

Answer 39

not recommended
P. zopfi is resistant to antimicrobial therapy

Question 40

If corynebacterium bovis is cultured on a cow with mastitis is it likely the causative organism?

Answer 40

rarely causes clinical mastitis– can be a frequent contaminant in milk samples

Question 41

Treatment of Trueperella pyogenes mastitis

Answer 41

Not effective– usually loss of quarter or culling

Question 42

Amputation of the teat in cases of Trueperella mastitis cases, should only be performed if what condition can be met?

Answer 42

If the cow can be segregated, to prevent environmental contamination

Question 43

What organisms cause Summer mastitis? A condition seen in Europe/Japan charaterized by swollen, hard, painful ammary gland containing purulent, foul-smelling secretion

Answer 43

anaeorbic bacteria: Peptococcus indolicus, Bacteroides spp., Fusobacterium necrophorum

Factultative anaerobes: S. dysgalactiae