Mastitis Flashcards
Presentation types
Sub/clinical
Dry period/lactation period
contagious/environmental
Affects
Quantity of milk
Quality - residue + fine for high SCC
Clinical
exposure to pathogen
Entry into teat + mammary gland
establish infection
always milk change
Grade 1
Milk change only
decreased milk yield
Grade 2 - acute
milk changes
change in udder
milk yield decrease
Grade 2 - chronic
as grade 2 acute but persistent changes
Grade 3
as grade 2 but systemic sick cow
Affects
Quantity of milk
Quality - residue + fine for high SCC
Treatment
Antibiotics - systemic, intramammary Depends on - sensitivity, pharmacokinetics, availability, costs, herd history, withdrawal time Oxytocin NSAID's Corticosteroids Fluid therapy Calcium Dextrose
Causative agents - Acute/clinical mastitis
(strep. agalactiae)
strep. dysgalactiae
strep. uberis
staph. aureus
E. coli
Sub - clinical - effects
No visual change in milk or cow
SCC
+ve Californian Mastitis Test (CMT)
Reduced milk yield
CMT
wipe, strip, sample, add, assess
Causative agents - Chronic/sub-clinical mastitis
Staph. aureus
strep. uberis
strep. agalactiae
corynebacterium bovis
History
Duration, development, stage of cycle, age, treatment, previous occurence, SCC
Clinical Exam
Systematic
Udder - inspection, palpation, lymph nodes
Milk exam
CMT
Why culture?
Can’t tell by clinical presentation
Sensitivity for AB
40% returns sterile
Sampling - where from?
Bulk tank
pooled sample of 1 cow
individual quarter sample
Prevention
not dependent on tube
different per bug + farmer
Entry of microorganisms into mammary gland
Galactogenic-most common
Haematogenous - eg tb + brucellosis
Percutaneous - wounds
Resistance to infection - Teat canal
Smooth muscle shincter
Keratin - cationic protiens to lyse gram +ve
- fatty acids - anti bacterial
Furstenburg rosette - physical barrier, fatty acids,
plasma cells
Resistance to infection - Leukocytes
Neutrophils -acute infl + later macrophages
Lymphocytes
Resistance to infection - Humoral factors
Lactoferin = iron binding protein, inhibits bacteria
- from secretory epithelium + neutophil granules.
Defensins - antimicrobial peptides
Immunoglobulins -IgG (IgM + IgA)
Peracute gangrenous mastitis
staph. aureus
occurs aroung parturition - death can be in hours
Gross - swollen painful, progress to moist gangrene, dark blue/black, cold, dark haemorrhagic lobules, ventral abdominal oedema, may comatose due to toxaemia
Acute mastitis - micro
interstitial oedema with neutophilic infiltration of interstitium + acini
Vacuolation + desquamation of acinar + ductal epithelium
Chronic mastitis - micro
fibroplasia with obliteration of acini
obstruction of ducts by polyps
retention cysts anterior to blocked ducts
eventual permanent loss of secretory tissue
Subclinical mastitis
10-40x more prevalent than clinical mastitis
no gross infl or changes in milk
detection by estimation SCC in milk
<200,000 cells per ml for whole udder denotes absence of infection
Subclinical mastitis progression
initial flare up
repair by fibrosis
further flare up
progressive fibrosis
Chronic subclinical mastitis - gross
hard and atrophic
Chronic subclinical mastitis - micro
similar to chronic mastitis following acute mastitis
permanent loss of secretory tissue
Lactating mastitis agents
staph. aureus
e. coli
strep. uberis
strep agalactiae
strep. dysgalactiae
mycoplasma bovis
corynebacterium bovis
staphyloccocus aureus
habitat - skin + mucous membrane enter through teat canal phagocytosis + killing in milk is inefficient 70% of strains B-lactamase +ve doesnt always invade udder tissue
staph. aureus - pathogenicity factors
a-toxin (potent necrotizing toxin) b-toxin (sphingomyelinase) TSST-1 (superantigen) polysaccharide capsule in vivo protein A no vaccine
streptococcus agalactiae
streptolysin S STST-1 (superantigen) enzymes - hyaluronidase, lipase polysccharide capsule habitat - teat canal host adapted - slow, progressive, chronic no vaccine
strep. dysgalactiae
STST-1 (superantigen) enzymes - hyaluronidase, lipase polysccharide capsule habitat - outside udder teat needs trauma to invade not host adapted - acute + infl no vaccine
strep. uberis
habitat - environment
needs trauma to invade
no vaccine
Escherichia coli
acute mastitis antimicrobial resistance a-haemolysin CNF-1 endotoxin Fe-acquisition K-types pili vaccine doesnt have O side chain
Mycoplasma bovis
habiat - genital & resp tract
mycoplasma mastitis
milk yield dramatically decreased
may reach udder by haematogenous spread
dry cow mastitis agents
arcanobacterium pyogens
strep. dysgalactiae
peptostrep indolicus
contagious mastitis
organisms prefer to live in udder + teat skin
often cause subclinical infection
most spread from cow to cow at milking
contagious mastitis - agents
strep. agalactiae
strep dysgalactiae
staph aureus
minor - corynebacterium bovis
environmental
sporadically gain entry to udder
tend to be rapidly eliminated or cause v.serious mastits
if quarter infected in dry period can persist to early lactation problems
environmental factors
from dirty environment
housing design + management
cubicle design
Somatic cell counts (SCC)
infl cells + epithelial cells (increase towards end of lactation + after calveing)
infl cells increase in infection
clinical = millions of cells, subclinical = >200,000/ml
Bulk milk SCC
Target 400,000
Contagious control
eliminate reservoirs of infection
5 point plan
Prompt detection + treatment of clinical cases
post milking teat dip
dry cow therapy
cull persistent offenders
regular servicing + maintenance of milking machines
Prompt detection + treatment of clinical cases
detect in parlour
fore milking
parlour hygene - gloves, no udder cloth
post milking teat dipping (PMTD)
allow teat sphincter to close to stop invading bacteria
disinfectant kills bacteria on skin + helps keep teat skin in good condition
iodophores, chlorine based, chlorhexidine, quaternary ammonium compounds
dip cup, spray, auto exit systems
dry cow therapy (DCT)
a) long acting antibiotics
aims to remove existing sub clinical infections + prevent establishment of new infections in dry period
b) teat sealent
inert substance infused into teat canal + blocks it so stops entry of becteria
cull persistent offenders
3 or more cases during 1 lactation
persistent high indicidual SCC and doesnt respond to treatment
regular servicing + maintenance of milking machines
machine often overlooked
vacuum - plenty vacuum reserve, steady suction, liner slips down the teat
serve frequently + check for mods of machine
Environmental control
teat prep - clean + dry
appropriate cubicle space
