Mastitis - Clinical Presentation

Question 1

How is the milk different in clinical and subclinical mastitis?

Answer 1

Clinical - can see clots

Subclinical - only know when perform CMT/ assess cell counts

Question 2

When does most infection which results in mastitis occur?

Answer 2

During the dry period

Question 3

What may be responsible for mastitis which is seen in the first 50 days of milking?

Answer 3

Infection in dry period

Either only noticed when cows brought inside, or less able to fight infection due to metabolic demands of milking

Question 4

What are the two broad categories of sources of bacteria which can cause mastitis?

Answer 4

Contagious

Environmental

Question 5

How can poor cubicles lead to increased rate of mastitis?

Answer 5

Cows will lie down in passageways

Udders come into contact with more faeces

Question 6

Which bacterial causes of mastitis are more ‘opportunistic’ ?

Answer 6

E. coli
Strep uberis
Strep dysgalactiae

Question 7

Which bacterial causes of mastitis are more ‘host adapted’ ?

Answer 7

Strep agalactiae
Staph aureus
Strep dysgalactiae

Question 8

Where might klebsiella be found?

Answer 8

Likes wet conditions - leaking water troughs

Question 9

What factors affect the presentation of mastitis?

Answer 9

Host
Environment
Agent

Question 10

Why should you be cautious of low reported levels of mastitis on farm?

Answer 10

suggests poor farm detection

Question 11

How can lower cell counts benefit milk?

Answer 11

Makes it last longer

Question 12

When is there a new case of mastitis in the same cow which has previously had mastitis?

Answer 12

in DIFFERENT quarter

Question 13

How can mastitis affect the quality and quantity of milk?

Answer 13

Quantity - loss of actual and potential

Quality - residues from antibiotics/analgesics
- High SCC - financial penalty

Question 14

How can the milking process increase the risk of mastitis?

How can you minimise this risk?

Answer 14

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

Question 15

Describe the basic progression of events which results in clinical mastitis.

Answer 15

Exposure to pathogen

Entry in the teat and mammary gland

Establishment of infection

Question 16

What is ALWAYS seen in clinical mastitis?

Answer 16

Changes in the milk

Question 17

Describe GRADE 1 clinical mastitis

Answer 17

Milk change only (clots, more serous)

Decreased milk yield

Question 18

Describe GRADE 2: acute clinical mastitis

Answer 18

Milk changes, changes in UDDER, milk yield decreases

Question 19

Describe GRADE 2: chronic clinical mastitis

Answer 19

Same as grade 2 acute, but persistent changes
- decreased number of functional alveoli result in decreased yield
(+milk changes, changes in udder)

Question 20

Describe GRADE 3 clinical mastitis

Answer 20

Same as grade 2 (decreased yield, milk changes, udder changes)
+ SYSTEMIC sick cow

Question 21

What are the bacterial causes of acute clinical mastitis?

Answer 21

Strep uberis
E. coli
Staph aureus
coagulase negative staph

(Strep a and dys galactiae) LESS IMPORTANT

Question 22

What may you observe in a cow with subclinical mastitis?

What would additional testing reveal?

Answer 22

Reduced milk yield

Positive CMT
Increased SCC

Question 23

How do you perform a CMT?

Answer 23

Wipe teats
Pre-strip 
Sample from each quarter (REMEMBER WHICH WELL WHICH)
Add equal volume reagent 
Assess results - more viscous = POSITIVE

Question 24

CMT: Why do you need to wipe the teat first?

Answer 24

To prevent dirt falling into the wells and affecting results

Question 25

CMT: Why do you need to pre-strip before testing?

Answer 25

Prevent false positives Stagnant milk has an increased SCC Makes test more specific

Question 26

CMT: What should you look for before adding the reagent ?

Answer 26

Clots in milk and general appearance (is it serous etc.?)

Question 27

CMT: How does the reagent interact with cells to give a positive result?

Answer 27

Dissolves membrane and releases DNA Sticky and firm viscosity = POSITIVE

Question 28

What are the main causes of chronic/subclinical mastitis?

Answer 28

Staph aureus Strep uberis Strep agalactiae ? Corynebacterium bovis

Question 29

Other than CMT, how can milk be assessed?

Answer 29

Electrical conductivity In-line SCC Spectroscopy

Question 30

How can electrical conductivity of milk indicate mastitis?

Answer 30

Increased conductivity = mastitis Increased sodium and chloride ions

Question 31

What history should be taken when investigating mastitis?

Answer 31

``` Duration Development Stage of lactation/gestation Age Treatment and its response Previous episodes SCC from NMR Other cases in herd? Records? ```

Question 32

What clinical exam should be carried out for suspected mastitis?

Answer 32

Systematic clinical exam Udder exam - inspection - palpation - udder, teat canal, cistern - lymph nodes Milk exam Milk sample - CMT

Question 33

How should you treat mastitis?

Answer 33

Antibiotic - systemic/ intramammary Oxytocin - drain milk - increase milk let down - flush NSAIDS - pain relief Corticosteroids - potentially for inflammation

Question 34

Why do you need to be careful when giving intramammary antibiotics?

Answer 34

DRY COW antibiotics have MUCH LONGER withdrawal period DONT MIX THEM UP

Question 35

What does your choice of antibiotic depend on?

Answer 35

``` Sensitivity Pharmacokinetics Availability Costs Herd history ```

Question 36

What should be given to cows suffering from toxic mastitis?

Answer 36

Fluid therapy - cows cant get to water trough Calcium Dextrose

Question 37

When would you culture for cases of mastitis?

Answer 37

Recurrent cases Persistent infection Rise in SCC Need to treat BEFORE results come back

Question 38

What milk sampling can be performed?

Answer 38

Bulk tank sample Pooled sample of one cow Individual quarter sample

Question 39

How do you perform an individual quarter sample?

Answer 39

``` 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 ```

Question 40

Why might some cultures return sterile?

Answer 40

S aureus doesn’t culture easily