6.2.2: Mastitis

Question 1

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?

Answer 1

First 30 days after calving = dry period origin

Question 2

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?

Answer 2

Over 30 days into lactation = lactation origin

Question 3

What key questions are essential to forming a mastitis control plan for a herd?

Answer 3

1. Is it dry period origin or lactation period origin?
2. Is it environmental or contagious?

Question 4

How do you differentiate between a mastitis that is caused by contagious vs environmental pathogens?

Answer 4

• 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

Question 5

What 2 categories of data are necessary to monitor mastitis at a herd level?

Answer 5

• Somatic cell count - usually readily available
• Clinical mastitis data - relies on farmer detection and record-keeping

Question 6

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.

Answer 6

True
* This is useful at a herd level.
* It does not necessarily hold true for every individual cow.

Question 7

How do we monitor SCC across the dry period? What does this tell us?

Answer 7

• 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

Question 8

This is about monitoring across the dry period.
A and B

Answer 8

A - Reason: new IMI prevented
B - Treatment outcome: Success :)

Question 9

This is about SCC monitoring across the dry period.
C and D

Answer 9

C - Reason: New IMI acquired.
D - Treatment outcome: Failure :(

Question 10

E and F

Answer 10

E - Reason: existing IMI cured and new IMI prevented
F - Treatment outcome: Success :)

Question 11

G and H

Answer 11

G - Reason: Existing IMI not cured OR existing IMI cured and new IMI acquired
H - Treatment outcome: Failure :(

Question 12

What does this graph show us?

Answer 12

• 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.

Question 13

How can we detect mastitis?

Answer 13

• 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

Question 14

Characteristics of contagious pathogens (mastitis)

Answer 14

• 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

Question 15

Characteristics of environmental pathogens (mastitis)

Answer 15

• 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

Question 16

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.

Answer 16

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

Question 17

Which is more common in UK dairy herds currently: environmental or contagious origin mastitis?

Answer 17

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)

Question 18

Which is more common currently in UK dairy herds: dry period or lactation origin mastitis?

Answer 18

50/50 split between dry period or lactation origin

Question 19

When in the dry period is the cow most at risk of acquiring a new mastitis?

Answer 19

1. At drying off
2. Coming close to calving (when there is colostrogenesis)

Question 20

Based on milk recording data, how would you classify a chronic case of mastitis?

Answer 20

In the last 2 out of 3 milk recordings, the SCC has been >200,000