Flashcards in Bovine Mastitis Deck (143)
What should you monitor in the parlour?
Visual changes in udder/cow (Off food? Pyrexia? Depressed?)
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
Bulk tank bactoscan
Bacteriology (bulk tank/individual/high SCC)
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?
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?
Milk processor company
Measured weekly but can get daily
Give a treatment plan for chronic high cell count cows
1. Treat during lactation according to culture and sensitivity
2. Dry off and treat-better bacteriological cure rate
3. 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
LPC thermoduric count and pseudomonas
Total Staphylococcal count
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
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?
1. Wear gloves
2. Clean, disinfect and dry the teat
3. Discard 10-15ml of foremilk
4. 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)
5. Sample close teats then far away ones (avoid contamination)
6. Keep sample container horizontal
7. Teat-dip afterwards
How would you interpret finding more than 3 bacteria on an individual cow bacteriology?
Probably a contaminated sample
How would you interpret finding no growth of bacteria on an individual cow bacteriology?
Cow is intermittently shedding or has had antibiotics
How would you interpret finding more than 1 major pathogen on an individual cow bacteriology?
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?
-Inadequate rest phase in pulsators/pulsators set too fast (poor teat circulation)
-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
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?
Why may a cow kick/paddle when being milked?
How many cows should you score when teat scoring?
20% of cows in each pen
What are the 4 scores for teat scoring?
2= smooth (best)
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?
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?
-Allows early detection of mastitis
-Stimulates milk let down reflex
Which hormone stimulates milk let down?
When is it released?
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%)
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?
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)
Give the order cows should be milked in
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?
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
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)?
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
What kind of pathogen is Trueperella pyogenes (ie contagious or environmental)?
How would you identify Trueperella pyogenes bacteriologically?
Small haemolytic colonies on blood agar
How would you identify Strep uberis bacteriologically?
-Small alpha haemolytic colonies on blood agar
-Edwards plate: aesculin hydrolysis -> plate turns black
What kind of pathogen is Strep uberis (ie contagious or environmental)?
Is Strep uberis gram +ve or -ve?
Gram +ve cocci in chains
Is E.coli gram +ve or -ve?
Gram -ve, short stumpy rods
What kind of pathogen is E.coli (ie contagious or environmental)?
How would you identify E.coli bacteriologically?
EMB agar: metallic green sheen to colonies
How would you identify Klebsiella bacteriologically?
Large mucoid colonies
What kind of pathogen is Klebsiella (ie contagious or environmental)?
Is Klebsiella gram +ve or -ve?
Gram -ve rods
Is Pseudomonas gram +ve or -ve?
Gram -ve, slender long rods, medium-sized
What is the prognosis like for Pseudomonas?
Poor as typically very resistant
What kind of pathogen is Pseudomonas (ie contagious or environmental)?
How would you identify Pseudomonas bacteriologically?
Green pigmentation on nutrient agar
How long is the dry period?
Typically 60 days but can be shortened to 42-45 days
How would you interpret a California Mastitis Test?
If milk becomes clumpy/gloopy -> positive result
When should you replace a liner from a cluster?
After 2500 milkings
Why do we use dry cow therapy?
To clear persistent infections (contagious pathogens eg Staph aureus) and protect against new ones (environmentl pathogens eg E.coli)
Which pathogens cause summer mastitis?
Arcanobacter/trueperella pyogenes (necrosis)
Strep dysgalactiae (1o infection?)
Peptococcus indolicus (foul smell)
What are the main antibiotics in UBRO red?
Penecillin as procaine salt 300mg, + Framycetin (Neomycin) + Penethamate (Penecillin ester)
Give some disadvantages of dry cow therapy
-Lower cell count (more prone to acute mastitis?)
-Hygiene during application -> new infections
-Product must have wide spectrum of activity
-Need to treat 100% of quarters to protect 15% of herd
When should you use teat sealants?
In cows with cell counts below 200,000 and no case of mastitis in previous lactation
What are the main ingredients of teat sealants?
4g of suspension containing 65% bismuth subnitrate
How do teat sealants work?
Remain as a paste within the base of the teat cistern and teat canal until stripped out at calving
What is Arlagarden?
Vet must complete a form which states which dry therapy is being used on the farm and why, and some measures towards a more selective approach to dry cow therapy
Cows not treated with a sealant are how many times more likely to get mastitis?
50% more likely
With selective dry cow therapy, which cows should you give teat sealants to?
Cows: <150,000 cell/ml
1st lactation heifers: <125,000 cell/ml
Must all have no clinical cases of mastitis in this lactation
What should you do before inserting an intra-mammary tube (antibiotic)?
Do after milking and cleaning of parlour
Pre-dip and allow kill time of 30s+
Loads of surgical spirit and cotton wool
Clean teat end until no more comes off
Which antibiotics are typically in intra-mammary tubes?
Cloxacillin +/- ampicillin
(Aim is to target Staphs primarily then broaden out)
Give some problems with mis-judging calving dates when using intra-mammary antibiotic tubes
If the product has too short a duration: risk of re-infection
If the product has too long a duration: will have to discard milk if calf is born whilst cow is still being treated
What is the average post-calving milk withhold of intra-mammary tubes?
Used to be 96hrs, but can now sell milk straight away after removing sealant
What is the average meat withold time of intra-mammary tubes?
10-30 days (most are 28 days)
What is a delvotest?
Tests milk for all antibiotic residues
How could you test milk for antibiotic residues?
Delvotest tests for residues of all/most antibiotics
Or can do a quick dip test for beta lactams
What is Tilmicosin licensed for?
Staph aureus in sheep not cattle
Give some other treatments you could use at drying off
Other long-acting macrolides:
(last 3 not licensed for milking cows)
Why might you not need to treat all mastitis cases?
-Some may be due to yeast
-Some will self-cure
-Some are culture negative
-Some farms don't treat mild gram-ve infections during lactations
Why may a mastitis treatment fail?
-Bacterial dormancy (ie duration of tx isn't long enough)
-L-forms are resistant to beta lactams as don't have a cell wall
-Reduced host response (steroids, stress)
-Pharmacokinetic limitations (eg binding of AB to milk/serum protein, intracellular parasitism, diffusion barriers due to eg oedema)
Why may antibiotics not reach the site of infection in adequate concentrations?
-Too low a dose
-Too long a dose interval
-Too short a treatment period
Is milk acidic or alkaline?
How can mastitis affect the blood/milk barrier?
Can cause it to break down
Which antibiotics are best for treating E.coli mastitis?
Potentiated sulphonamides (better penetration)
Why would MRSA be an issue in dairy cows?
Cross-infection between humans and cattle
Which antibiotic is good against gram -ve bacteria?
Are all streps and staphs gram +ve or -ve?
Is lincomycin good for treating gram +ve or -ve bacteria?
Give an example of a broad spectrum combination for treating gram +ve and -ve bacteria
Lincomycin (gram +ve) with neomycin (gram -ve)
What is 'pusle therapy'?
Treatment with ABs by treating then witholding then treating etc
What is 'blitz therapy?'
Treatment of whole herd with ABs (Strep agalactiae only)
Blitz therapy can only be used with which bacteria?
What is the typical therapeutic strategy for ABs during lactation?
12 hr intervals for 3 consecutive milkings
Do intra-mammary or systemic ABs result in a quicker return to milk production and more milk production?
What is 'Startvac'?
Vaccine for mastitis (against E.coli, Staph areus and coliforms; hinders the production of biofilm)
When is Startvac given?
Day 97 post-calving, 10 days pre-calving, and 45 days pre-calving
How long does Startvac protect for?
Up to 130 days post-calving
How could you tell that a cow is painful?
Increased sensitivity to touch, hyperalgesia, increased kicking, increased HR and RR, increased rectal temp
Give some NSAIDs you can use in cattle
How would you treat the following case:
Young cow, first case of mastitis this lactation, high SCC previous month
Intra-mammary and systemic ABs
How would you treat the following case:
End of lactation, high SCC
Dry off and treat with dry cow therapy +/- injectable AB
How would you treat the following case:
Old cow, 3rd case this lactation, chronic high SCC
How would you treat the following case:
Young cow, first case, low SCC previous month
No treatment- watchful waiting
What should you do to every mastitis case before treating?
What does 'ADF' stand for?
Automated dipping and flushing of cluster
What is Velactis?
New product: macrolide, dopamine receptor agonist -> inhibits prolactin
An aid to drying off as reduces milk production -> reduced milk leakage at drying off -> reduced risk of intramammary infections
What is Pegbovigrastim?
New product: restores normal neutrophil function during the peri-parturient period -> fewer cases of clinical mastitis
What is the difference between clinical and sub-clinical mastitis?
Clinical: visible grossly; changes in milk/udder/cow
Subclinical: infection present but no visible clinical signs. Changes in SCC, milk quality and yield
Give the possible consequences of a mastitis infection
-Cow clears the infection and returns to normal milk production
-Doesn't clear the infection and develops chronically-persistent bacterial infections -> spreads within herd
-Permanent damage to udder tissue and reduced milk yield
-Death from toxaemia or PTS
How does the innate immune response work?
WBCs -> activate acquired immune response -> humoral and cellular response (B and T lymphocytes, Abs)
How is the teat skin designed to fight bacteria?
How can it be compromised?
Stratified squamous epithelium with bacteriostatic fatty acids (to prevent colonisation of bacteria)
Can be compromised by bruising, chapping, trauma, teat lesions, milking machine (eg vacuum)
How often should a milking machine be serviced?
Every 12 months
How long does it take the teat sphincter muscle to close?
How does the teat canal stop bacteria entering the udder?
Teat sphincter muscle acts as a barrier
Keratin lining traps bacteria and is continuously sloughing
Keratin plug forms over teat when cow is dried off
What % of cows form an effective seal from the keratin plus at drying off?
What make up the innate immune response inside the udder?
Resident leukocytes (macrophages, neutrophils, T lymphocytes)
Lactoferrin (inhibits growth of bacteria requiring iron eg E.coli)
Complement (opsonisation of bacteria; attracts phagocytes)
Which antibodies to B lymphocytes produce initially and after repeated exposure to bacteria?
Initially: IgG1, IgM
After repeated exposure: IgG2 ('vaccination')
Which antibodies are most important when dealing with bacteria in the udder?
Which antibodies function in the udder? What do they do?
IgM: fixates complement for opsonisation of pathogens, agglutination of bacteria, neutralises toxins
IgA: agglutination of bacteria, neutralises toxins
IgG1: opsonisation of bacteria
Give some factors that affect mammary gland immunity
Stage of lactation
Cows in which period are more likely to acquire new mastitis infections?
Early and late dry period (although clinical disease is usually seen in the first 6 weeks after calving)
Why is WBC function reduced in the dry period and post-calving?
Early dry period: neutrophils are present but full of fat and cellular debris -> impaired function
-Increasing levels of IgG1 may interfere with neutrophil function
-Reduced neutrophil recruitment and phagocytic ability
-Macrophages have reduced phagocytic function
How does nutrition affect mastitis?
-Negative energy balance -> impaired activity and lower numbers of leucocytes
-Vit E and selenium deficiency -> slow migration and weaker activity of leucocytes
-SARA: reduced appetite -> reduced DMI -> NEB. Diarrhoea
-Hypocalcaemia -> weakened teat sphincter mechanism
What is the mastitis vaccine and what does it protect against?
Protects against Staph aureus, coliforms, and coagulase-negative Staphylococcus
Reduces incidence of sub-clinical mastitis and severity, and incidence of clinical mastitis
Are Strep agalactiae and dysgalactiae contagious or environmental?
If a cow develops mastitis in the first few months of lactation, what does this tell us about the infection?
It was likely picked up during the dry period