Introduction and immunity

Question 1

what is mastitis?

Answer 1

inflammation of the mammary gland

Question 2

what are the two types of mastitis?

Answer 2

clinical
subclinical

Question 3

what is subclinical mastitis?

Answer 3

infection present but no clinical signs, there will be changes in the SCC and milk quality/quantity

Question 4

what is clinical mastitis?

Answer 4

inflammation of the udder with visible change to milk, udder and cow

Question 5

what are the grades of clinical mastitis?

Answer 5

1, 2A, 2C, 3

Question 6

what is grade 1 clinical mastitis?

Answer 6

mild mastitis with some changes in milk (clots or consistency)

Question 7

what is grade 2A clinical mastitis?

Answer 7

acute mastitis with changes to the milk, the udder is hot and painful

Question 8

what is grade 2C clinical mastitis?

Answer 8

chronic mastitis with changes to the milk, the udder is hard and lumpy

Question 9

what is grade 3 clinical mastitis?

Answer 9

changes seen to milk and udder with a systemically unwell cow

Question 10

what are the two groups of mastitis pathogens?

Answer 10

environmental and contagious

Question 11

what are the main environmental mastitis pathogens?

Answer 11

E. coli
Strep. uberis
Klebsiella spp.

Question 12

what are the main contagious mastitis pathogens?

Answer 12

Strep. uberis
Strep. agalactiae
Strep. dysgalactiae
Staph. aureus
Coagulase negative staphs
Mycoplasma spp.

Question 13

what pathogen is both an environmental and contagious mastitis pathogen?

Answer 13

Strep. uberis

Question 14

where do the contagious mastitis pathogen live?

Answer 14

have to live on an animal (the cow)

Question 15

what are the possible consequences if the cow doesn’t clear a mastitis infection?

Answer 15

chronic infection (spreads to other cows)
permanent damage (reduced milk yield)
death (toxaemia)

Question 16

how does mastitis effect the milk product produced by the cow?

Answer 16

high SCC milk will go off quicker

Question 17

what is the legal limit of SCC to be able to sell milk?

Answer 17

400 000 /ml

Question 18

what are the two defence systems of the mammary gland?

Answer 18

innate immune system (first line)
acquired immune system

Question 19

what are the parts of the innate immunity of the mammary gland?

Answer 19

resident leucocytes
antimicrobials in milk
teat skin
teat canal

Question 20

what is the teat skin protect against mastitis?

Answer 20

aims to prevent colonisation of bacteria by having stratified squamous epithelium plus bacteriostatic fatty acids

Question 21

how can we ensure the teat skin remains a functional part of the immune system?

Answer 21

post-milking teat dip emollients
prompt treatment of lesions
good milking machine function

Question 22

when is a major risk period for entry of bacteria in relation to the teat canal?

Answer 22

during and after milking (stays open for 20-30 minutes post milking)

Question 23

how does the teat canal protect against mastitis bacteria?

Answer 23

remains closed when not being milked
keratin lining traps bacteria then continuously sloughs
keratin plug forms during dry period

Question 24

how long does it take the teat canal to close after milking?

Answer 24

20-30 minutes

Question 25

what are some possible cause of teat canal damage?

Answer 25

milking machines (hyperkeratosis) external trauma teat lesion teat cannulas

Question 26

how can teat end hyperkeratosis be graded?

Answer 26

no ring (N) smooth/slightly rough (S) rough ring (R) very rough ring (VR)

Question 27

what are some causes of teat end hyperkeratosis?

Answer 27

excessive milking vacuums faulty pulsators liner types teat shape

Question 28

why are rough/very rough rings of teat end hyperkeratosis a risk factor for mastitis?

Answer 28

teat end doesn't close properly and the crevices provide a good environment for pathogens

Question 29

how can we protect the teat canal and end?

Answer 29

genetics good milking machine function allow loafing time post-milking teat sealants at dry off

Question 30

what are the resident leucocytes present in the mammary gland?

Answer 30

macrophages, neutrophils, T lyphocytes

Question 31

what is the function of the resident leucocytes of the mammary gland?

Answer 31

phagocytosis/killing of pathogens trigger acquired immune system by release of pro-inflammatory mediators and antigen presentation

Question 32

what are the antimicrobial substances present in milk?

Answer 32

lactoferrin lactoperoxidase lysoymes free complement

Question 33

what is lactoferrin?

Answer 33

iron chelating protein that inhibits the growth of bugs that require iron (eg. E. coli)

Question 34

is lactoperoxidase bacteriostatic or bactericidal?

Answer 34

bacteriostatic

Question 35

are lysozymes bacteriostatic or bactericidal?

Answer 35

bactericidal

Question 36

what are the parts of the acquired immune system of the mammary gland?

Answer 36

B and T lymphoctyes inflammatory cytokines

Question 37

what are the functions of B lymphocytes?

Answer 37

produce IgM and IgG after initial exposure then will produce IgG2 antibodies if there is a repeated exposure present antigen to T lymphocytes

Question 38

what are the two types of T lymphocytes?

Answer 38

T helper cells T cytotoxic cells

Question 39

what is the function of T helper cells?

Answer 39

produce cytokines following antigen recognition to stimulate an immune response

Question 40

what is the function of T cytotoxic cells?

Answer 40

eliminate host cells invaded by pathogens

Question 41

what effects mammary gland immunity?

Answer 41

genetics (immunity and conformation) stage of lactation nutrition vaccination stress

Question 42

what can be genetically select cattle for which will decrease the risk of mastitis?

Answer 42

low SCC udder confirmation yield

Question 43

what are high risk times in lactation for mastitis?

Answer 43

dry period and early lactation

Question 44

why is early and late dry period a risk period of mastitis?

Answer 44

early - teats still open late - colostrum good media for bacteria and make start to leak from teats

Question 45

why is the dry period a risk period for mastitis?

Answer 45

cessation of milking. - increased mammary pressure and widened teat canal bacteria not flushed out no teat dipping keratin plug takes time to form

Question 46

why is white blood cell (neutrophil) function reduced in the early dry period?

Answer 46

udder is full of fat and cellular debris from lactation that will interfere with their function

Question 47

why is white blood cell function reduced in the peri-parturient cow?

Answer 47

increased levels of IgG for colostrogeneis can interfere with neutrophil function hormone changes (cortisol, progesterone...) suppress the neutrophil recruitment and phagocytic ability reduced feed intakes and hence poor nutrition

Question 48

how can poor nutrition increase mastitis risk?

Answer 48

negative energy balance - leucocyte activity impaired vitamin E/selenium deficiency leads to weak leucocytes SARA - reduced intakes leading to negative energy balance, diarrhoea leads to poor cow hygiene hypocalcaemia - weaken teat sphincter mechanism

Question 49

how can SARA increase the risk of mastitis?

Answer 49

reduced intakes causing negative energy balance diarrhoea leads to poor cow hygiene

Question 50

can mastitis be vaccinated against?

Answer 50

yes - startvac

Question 51

what does startvac protect against?

Answer 51

Staphylococcus aureus coliforms coagulase negative Staphylococci