6.2.2: Mastitis Flashcards
A cow that presents with clinical mastitis in the first 30 days of lactation is considered to have mastitis of a lactation or dry period origin?
First 30 days after calving = dry period origin
A cow that presents with clinical mastitis at over 30 days of lactation is considered to have mastitis of a lactation or dry period origin?
Over 30 days into lactation = lactation origin
What key questions are essential to forming a mastitis control plan for a herd?
- Is it dry period origin or lactation period origin?
- Is it environmental or contagious?
How do you differentiate between a mastitis that is caused by contagious vs environmental pathogens?
- Use the bulk milk somatic cell count (BMSCC)
- Over 300,000 cells/ml = likely to be a contagious pathogen
- Consider subclinical infections/persistency; contagious pathogens are well-adapted to persist in the udder
- Seasonality can be a good indicator of environmental rather than contagious and can still be observed in cows housed all year round
What 2 categories of data are necessary to monitor mastitis at a herd level?
- Somatic cell count - usually readily available
- Clinical mastitis data - relies on farmer detection and record-keeping
True/false: the majority of mastitis cases that present in the 1st month after calving are due to infections picked up in the dry period.
True
* This is useful at a herd level.
* It does not necessarily hold true for every individual cow.
How do we monitor SCC across the dry period? What does this tell us?
- Record SCC in last milking before drying, and in first milking after calving
- Compare 2 figures
- High –> low = we cured this :)
- High –> high = we did not cure OR we cured and then got another infection.
- Low –> high = picked up an infection
- Low –> Low = we prevented a new infection
This is about monitoring across the dry period.
A and B
A - Reason: new IMI prevented
B - Treatment outcome: Success :)
This is about SCC monitoring across the dry period.
C and D
C - Reason: New IMI acquired.
D - Treatment outcome: Failure :(
E and F
E - Reason: existing IMI cured and new IMI prevented
F - Treatment outcome: Success :)
G and H
G - Reason: Existing IMI not cured OR existing IMI cured and new IMI acquired
H - Treatment outcome: Failure :(
What does this graph show us?
- Spikes = when cow is most likely to pick up new infection (NOT the same as when mastitis is detected)
- High risk times: start of dry period, towards end of dry period (lactogenesis and approach to calving) into start of lactation
- Low risk times: middle of dry period. Risk tapers down as lactation continues.
How can we detect mastitis?
- Clinical exam/foremilking - for clots/consistency/colour of milk
- Conductivity - changes with inflammation. Fitted in some parlours.
- California Milk Test - crude but detects elevation in SCC (subclinical mastitis)
- Individual cow somatic cell counts (ICSCC) - useful for detecting subclinically affected cows
Characteristics of contagious pathogens (mastitis)
- Adapted to the mammary gland
- Can cause persistent infection and hard to get rid of
- Spread between the cows at milking
- Less common than environmental mastitis
- e.g. Staph aureus, Strep agalactiae, Strep dysgalactiae, Mycoplasma spp
Characteristics of environmental pathogens (mastitis)
- Opportunistic invaders from the cow’s environment
- Examples: S, uberis, Staph species other than Staph aureus, Coliforms such as E. coli , and Klebsiella, Pseudomonas, Proteus, Serratia species, Gram +ve bacilli, yeast, Prototheca
- Environmental mastitis is more common than contagious mastitis in the UK
True/false: bacteriology is vital to a mastitis investigation at both individual cow and herd level. Once the causative agent has been identified, it will be clear how to treat and control the mastitis.
False
* Bacteriology can be helpful, but identifying the causative pathogen does not tell you how it is behaving!
* Some bacteria have strains which will behave differently i.e. some environmental pathogens, some contagious
* Bacteriology is a tool in the box but other factors including cow SCC, no. of quarters affected, farm bulk SCC, prevalence of infection will affect the chance of cure and the control measures implemented going forward
Which is more common in UK dairy herds currently: environmental or contagious origin mastitis?
Environmental (>90% of dairy herd infection patterns)
Contagious (<10% of dairy herd infection patterns)
NB: more environmental due to good implementation of the 5 point plan. In areas where this plan is not as well adhered to, see more contagious mastitis (e.g. Ireland)
Which is more common currently in UK dairy herds: dry period or lactation origin mastitis?
50/50 split between dry period or lactation origin
When in the dry period is the cow most at risk of acquiring a new mastitis?
- At drying off
- Coming close to calving (when there is colostrogenesis)
Based on milk recording data, how would you classify a chronic case of mastitis?
In the last 2 out of 3 milk recordings, the SCC has been >200,000
