Bovine Mastitis Flashcards
What should you monitor in the parlour?
Fore milking
Visual changes in udder/cow (Off food? Pyrexia? Depressed?)
Teat/udder feel
Cow response to palpation
Californian Mastitis test
In line detectors (filters, electrical conductivity)
What can you monitor when investigating mastitis?
In parlour monitoring (clinical signs, fore milking etc)
Clinical case records
SCC
Bulk tank bactoscan
Bacteriology (bulk tank/individual/high SCC)
Multiplex PCR
Why might a bulk tank bactoscan be high?
Poor housing cleanliness Putting milk from clinical cases in bulk tank Poor plant cleaning High levels of mastitis on farm Poor teat cleanliness
Why do we do individual cow cell counts?
Identifies high cell count cows in herd, chronically infected and stage of lactation
What does a SCC of >200,000 cells/ml indicate?
Infected quarter with major pathogen
What is the target % of clinical cases of mastitis?
<30% (UK average is actually 45-65%)
A bulk milk cell count over which value would put a farmer under threat of not collecting milk any longer?
> 400,000
A cow will test positive on a California Mastitis Test if it has a SCC value of what?
> 300,000 from any quarter
What does a Bactoscan tell you?
Actual count of bacterial numbers in milk
Who carries out a Bactoscan?
When?
Milk processor company
Measured weekly but can get daily
Give a treatment plan for chronic high cell count cows
Identify pathogen
- Treat during lactation according to culture and sensitivity
- Dry off and treat-better bacteriological cure rate
- Cull chronically infected, older cows
Which treatment should you use for cows with chronic high cell counts if treating during lactation?
Extended courses of intra-mammary therapy for Staph aureus and Strep uberis eg cloxacillin for 6 days
Systemic eg tylosin, penethamate
Mini blitz-all high cell count cows together as a group and treat according to culture and sensitivity
Which treatment should you use for cows with chronic high cell counts if drying off and treating?
Dry cow intra-mammary antibiotic and systemic antibiotic eg tylosin
Milk exceeding which value for Bactoscan will be excluded from the supermarket supply?
50,000/ml, until under 50,000 for 3 months
What is included in a bulk tank bacteriology?
Total bacterial count Cell count LPC thermoduric count and pseudomonas Coliform count Total Staphylococcal count Staph aureus Identifies other pathogenic bacteria
Which cows should be sampled when doing individual cow bacteriology?
All clinical cases
High cell count cows
Give some possible problems with individual cow bacteriology
Contaminated samples
Some pathogens are only intermittently shed eg Staph aureus
May be no bacterial growth if cow has had antibiotics
How would you carry out a milk sample collection for individual cow bacteriology?
- Wear gloves
- Clean, disinfect and dry the teat
- Discard 10-15ml of foremilk
- Clean each teat end and orifice for 15-20 seconds with a cotton wool swab soaked in 70% alcohol (clean further ones before closer one)
- Sample close teats then far away ones (avoid contamination)
- Keep sample container horizontal
- Teat-dip afterwards
How would you interpret finding more than 3 bacteria on an individual cow bacteriology?
Probably a contaminated sample
Repeat
How would you interpret finding no growth of bacteria on an individual cow bacteriology?
Cow is intermittently shedding or has had antibiotics
Repeat
How would you interpret finding more than 1 major pathogen on an individual cow bacteriology?
Mixed aetiology
How would you interpret finding a major pathogen and a minor pathogen on an individual cow bacteriology?
The major pathogen is the causal agent
How is milk removed from the teat during milking?
Negative pressure is created outside the teat by applying a vacuum (42-48kpa) controlled by a regulator
Vacuum is applied intermittently (continuous -> would stop circulation in teat)
Where does the long milk tube of the cluster unit go?
To the bulk tank
How does the milking machine contribute to mastitis?
1) Damages the teats and teat ends
2) Acts as a vector for transfer of infection
How may the milking machine cause teat damage?
- Worn/hard/faulty liners
- Inadequate rest phase in pulsators/pulsators set too fast (poor teat circulation)
- Excess vacuum
- Over-milking
- Inadequate emolient in post-milking teat dip
- Poor pre-milking teat preparation (slow milk let down)
Which condition of the teat can occur due to damage from the milking machine?
Teat end sphincter hyperkeratosis
How would you recognise damaged teats?
Blue, oedematous, chapped or petechiations
How can milking machines transfer infections?
- Contamination of liners-transfer of pathogens in teat skin
- Wet miling (milk flushed up into teat canal carrying pathogens with it)
- Blocked air bleed
- Fluctuating/inadequate vacuum
Give a problem with air bleeds getting blocked on cluster units
Can cause flooding of the claw piece -> teat end impactions
How many pulsations should occur per minute in a milking cluster unit?
60
Why may a cow kick/paddle when being milked?
- Over-milking
- Faulty vacuum/pulsators
- Excess vacuum
- Hard liners
How many cows should you score when teat scoring?
20% of cows in each pen
What are the 4 scores for teat scoring?
1= normal 2= smooth (best) 3= rough 4= very rough
What is a problem with over-shedding of keratin on teat ends?
Bacteria can stick to keratin and cause infection
Do the front or back 2 teats produce the most milk?
Back 2 (hence the back 2 clusters are weighted)
What should be carried out before milking?
Fore-milking Teat disinfection (must dry after washing)
What should be carried out after milking?
Post-milking teat disinfection Loafing time (let cows stand to allow time for teat ends to close)
Why should we carry out fore-milking?
- Legal requirement
- Allows early detection of mastitis
- Stimulates milk let down reflex
Which hormone stimulates milk let down?
When is it released?
Oxytocin
Released in reponse to physical stimulation of teat
Give some common disinfectants used to clean teats before milking
Chlorohexidine (non-irritant, 0.35-0.5%) Iodophors (0.1-0.5%) Chlorine dioxide (active in presence of faeces)
Why should we clean teats post-milking?
To remove bacteria transferred to teats during milking (particularly contagious pathogens)
Why should cows have loafing time after milking?
Allows closure of the teat sphincter post-milking and prevents environmental infections
How much loafing time should cows have?
30 mins
Give a potential problem with loafing times
May exacerbate lameness
How can we prevent the spread of mastitis in the parlour?
- Milking order (milk clinical cases last)
- Cluster disinfection
Give the order cows should be milked in
1) Heifers
2) Fresh calvers
3) High yielders
4) Low yielders
5) High cell count cows
6) Mastitic cows
Describe a parlour wash routine
Clean milk out and remove bacteria deposited
Cold rinse (once daily)
Hot wash (once daily)
Rinse with hypochlorite
Acid and alkali washes (acid gets rid of calcium and protein, alkaliturns fat into soap and rinses out)
How hot does a parlour wash have to be?
85-90oC
What should you listen for in a parlour?
Liners slipping off Vacuum regulator (hissing sound if working)
How should you manage high cell count/mastitic cows in the parlour?
Use a separate cluster and disinfect between cows
Back flush the cluster with water and disinfectant between cows
Hypochlorite solution
Per-acetic acid
Describe the cure rate for mastitis caused by Staph aureus
Low (20-60%) as it exists intra-cellularly so can be recurrent
What kind of antibiotics should be used to treat Staph aureus?
Systemic (as it exists intra-cellularly)
What kind of pathogen is Staph aureus (ie contagious or environmental)?
Contagious
Is Staph aureus gram +ve or -ve?
Gram +ve cocci
How would you identify Staph aureus bacteriologically?
Forms cream-yellow colonies and is haemolytic on blood agar
Is Trueperella pyogenes gram +ve or -ve?
Gram +ve rods