Mastitis - Clinical Presentation Flashcards
How is the milk different in clinical and subclinical mastitis?
Clinical - can see clots
Subclinical - only know when perform CMT/ assess cell counts
When does most infection which results in mastitis occur?
During the dry period
What may be responsible for mastitis which is seen in the first 50 days of milking?
Infection in dry period
Either only noticed when cows brought inside, or less able to fight infection due to metabolic demands of milking
What are the two broad categories of sources of bacteria which can cause mastitis?
Contagious
Environmental
How can poor cubicles lead to increased rate of mastitis?
Cows will lie down in passageways
Udders come into contact with more faeces
Which bacterial causes of mastitis are more ‘opportunistic’ ?
E. coli
Strep uberis
Strep dysgalactiae
Which bacterial causes of mastitis are more ‘host adapted’ ?
Strep agalactiae
Staph aureus
Strep dysgalactiae
Where might klebsiella be found?
Likes wet conditions - leaking water troughs
What factors affect the presentation of mastitis?
Host
Environment
Agent
Why should you be cautious of low reported levels of mastitis on farm?
suggests poor farm detection
How can lower cell counts benefit milk?
Makes it last longer
When is there a new case of mastitis in the same cow which has previously had mastitis?
in DIFFERENT quarter
How can mastitis affect the quality and quantity of milk?
Quantity - loss of actual and potential
Quality - residues from antibiotics/analgesics
- High SCC - financial penalty
How can the milking process increase the risk of mastitis?
How can you minimise this risk?
If vacuum too extreme, or milking too long
Teat canal can ‘pop out’ resulting in keratosis
More susceptible to infection
PRE-STRIP and prep before milking
Describe the basic progression of events which results in clinical mastitis.
Exposure to pathogen
Entry in the teat and mammary gland
Establishment of infection
What is ALWAYS seen in clinical mastitis?
Changes in the milk
Describe GRADE 1 clinical mastitis
Milk change only (clots, more serous)
Decreased milk yield
Describe GRADE 2: acute clinical mastitis
Milk changes, changes in UDDER, milk yield decreases
Describe GRADE 2: chronic clinical mastitis
Same as grade 2 acute, but persistent changes
- decreased number of functional alveoli result in decreased yield
(+milk changes, changes in udder)
Describe GRADE 3 clinical mastitis
Same as grade 2 (decreased yield, milk changes, udder changes)
+ SYSTEMIC sick cow
What are the bacterial causes of acute clinical mastitis?
Strep uberis
E. coli
Staph aureus
coagulase negative staph
(Strep a and dys galactiae) LESS IMPORTANT
What may you observe in a cow with subclinical mastitis?
What would additional testing reveal?
Reduced milk yield
Positive CMT
Increased SCC
How do you perform a CMT?
Wipe teats Pre-strip Sample from each quarter (REMEMBER WHICH WELL WHICH) Add equal volume reagent Assess results - more viscous = POSITIVE
CMT: Why do you need to wipe the teat first?
To prevent dirt falling into the wells and affecting results
CMT: Why do you need to pre-strip before testing?
Prevent false positives
Stagnant milk has an increased SCC
Makes test more specific
CMT: What should you look for before adding the reagent ?
Clots in milk and general appearance (is it serous etc.?)
CMT: How does the reagent interact with cells to give a positive result?
Dissolves membrane and releases DNA
Sticky and firm viscosity = POSITIVE
What are the main causes of chronic/subclinical mastitis?
Staph aureus
Strep uberis
Strep agalactiae ?
Corynebacterium bovis
Other than CMT, how can milk be assessed?
Electrical conductivity
In-line SCC
Spectroscopy
How can electrical conductivity of milk indicate mastitis?
Increased conductivity = mastitis
Increased sodium and chloride ions
What history should be taken when investigating mastitis?
Duration Development Stage of lactation/gestation Age Treatment and its response Previous episodes SCC from NMR Other cases in herd? Records?
What clinical exam should be carried out for suspected mastitis?
Systematic clinical exam
Udder exam
- inspection
- palpation - udder, teat canal, cistern
- lymph nodes
Milk exam
Milk sample - CMT
How should you treat mastitis?
Antibiotic - systemic/ intramammary
Oxytocin - drain milk - increase milk let down - flush
NSAIDS - pain relief
Corticosteroids - potentially for inflammation
Why do you need to be careful when giving intramammary antibiotics?
DRY COW antibiotics have MUCH LONGER withdrawal period
DONT MIX THEM UP
What does your choice of antibiotic depend on?
Sensitivity Pharmacokinetics Availability Costs Herd history
What should be given to cows suffering from toxic mastitis?
Fluid therapy - cows cant get to water trough
Calcium
Dextrose
When would you culture for cases of mastitis?
Recurrent cases
Persistent infection
Rise in SCC
Need to treat BEFORE results come back
What milk sampling can be performed?
Bulk tank sample
Pooled sample of one cow
Individual quarter sample
How do you perform an individual quarter sample?
Clean udder Swab teat end (until no more dirt comes off) 2 pre-strips 2 ml in sterile container Label name, cow’s number and quarter
Why might some cultures return sterile?
S aureus doesn’t culture easily
