Introduction and immunity Flashcards
what is mastitis?
inflammation of the mammary gland
what are the two types of mastitis?
clinical
subclinical
what is subclinical mastitis?
infection present but no clinical signs, there will be changes in the SCC and milk quality/quantity
what is clinical mastitis?
inflammation of the udder with visible change to milk, udder and cow
what are the grades of clinical mastitis?
1, 2A, 2C, 3
what is grade 1 clinical mastitis?
mild mastitis with some changes in milk (clots or consistency)
what is grade 2A clinical mastitis?
acute mastitis with changes to the milk, the udder is hot and painful
what is grade 2C clinical mastitis?
chronic mastitis with changes to the milk, the udder is hard and lumpy
what is grade 3 clinical mastitis?
changes seen to milk and udder with a systemically unwell cow
what are the two groups of mastitis pathogens?
environmental and contagious
what are the main environmental mastitis pathogens?
E. coli
Strep. uberis
Klebsiella spp.
what are the main contagious mastitis pathogens?
Strep. uberis
Strep. agalactiae
Strep. dysgalactiae
Staph. aureus
Coagulase negative staphs
Mycoplasma spp.
what pathogen is both an environmental and contagious mastitis pathogen?
Strep. uberis
where do the contagious mastitis pathogen live?
have to live on an animal (the cow)
what are the possible consequences if the cow doesn’t clear a mastitis infection?
chronic infection (spreads to other cows)
permanent damage (reduced milk yield)
death (toxaemia)
how does mastitis effect the milk product produced by the cow?
high SCC milk will go off quicker
what is the legal limit of SCC to be able to sell milk?
400 000 /ml
what are the two defence systems of the mammary gland?
innate immune system (first line)
acquired immune system
what are the parts of the innate immunity of the mammary gland?
resident leucocytes
antimicrobials in milk
teat skin
teat canal
what is the teat skin protect against mastitis?
aims to prevent colonisation of bacteria by having stratified squamous epithelium plus bacteriostatic fatty acids
how can we ensure the teat skin remains a functional part of the immune system?
post-milking teat dip emollients
prompt treatment of lesions
good milking machine function
when is a major risk period for entry of bacteria in relation to the teat canal?
during and after milking (stays open for 20-30 minutes post milking)
how does the teat canal protect against mastitis bacteria?
remains closed when not being milked
keratin lining traps bacteria then continuously sloughs
keratin plug forms during dry period
how long does it take the teat canal to close after milking?
20-30 minutes
what are some possible cause of teat canal damage?
milking machines (hyperkeratosis)
external trauma
teat lesion
teat cannulas
how can teat end hyperkeratosis be graded?
no ring (N)
smooth/slightly rough (S)
rough ring (R)
very rough ring (VR)
what are some causes of teat end hyperkeratosis?
excessive milking vacuums
faulty pulsators
liner types
teat shape
why are rough/very rough rings of teat end hyperkeratosis a risk factor for mastitis?
teat end doesn’t close properly and the crevices provide a good environment for pathogens
how can we protect the teat canal and end?
genetics
good milking machine function
allow loafing time post-milking
teat sealants at dry off
what are the resident leucocytes present in the mammary gland?
macrophages, neutrophils, T lyphocytes
what is the function of the resident leucocytes of the mammary gland?
phagocytosis/killing of pathogens
trigger acquired immune system by release of pro-inflammatory mediators and antigen presentation
what are the antimicrobial substances present in milk?
lactoferrin
lactoperoxidase
lysoymes
free complement
what is lactoferrin?
iron chelating protein that inhibits the growth of bugs that require iron (eg. E. coli)
is lactoperoxidase bacteriostatic or bactericidal?
bacteriostatic
are lysozymes bacteriostatic or bactericidal?
bactericidal
what are the parts of the acquired immune system of the mammary gland?
B and T lymphoctyes
inflammatory cytokines
what are the functions of B lymphocytes?
produce IgM and IgG after initial exposure then will produce IgG2 antibodies if there is a repeated exposure
present antigen to T lymphocytes
what are the two types of T lymphocytes?
T helper cells
T cytotoxic cells
what is the function of T helper cells?
produce cytokines following antigen recognition to stimulate an immune response
what is the function of T cytotoxic cells?
eliminate host cells invaded by pathogens
what effects mammary gland immunity?
genetics (immunity and conformation)
stage of lactation
nutrition
vaccination
stress
what can be genetically select cattle for which will decrease the risk of mastitis?
low SCC
udder confirmation
yield
what are high risk times in lactation for mastitis?
dry period and early lactation
why is early and late dry period a risk period of mastitis?
early - teats still open
late - colostrum good media for bacteria and make start to leak from teats
why is the dry period a risk period for mastitis?
cessation of milking. - increased mammary pressure and widened teat canal
bacteria not flushed out
no teat dipping
keratin plug takes time to form
why is white blood cell (neutrophil) function reduced in the early dry period?
udder is full of fat and cellular debris from lactation that will interfere with their function
why is white blood cell function reduced in the peri-parturient cow?
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
how can poor nutrition increase mastitis risk?
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
how can SARA increase the risk of mastitis?
reduced intakes causing negative energy balance
diarrhoea leads to poor cow hygiene
can mastitis be vaccinated against?
yes - startvac
what does startvac protect against?
Staphylococcus aureus
coliforms
coagulase negative Staphylococci
