Flashcards in Mastitis Deck (59):
WHat are the 2 forms of mastitis? Which is ht emost common?
- Subclinical [most common]
What are the 2 forms of clinical mastitis?
Dry [environment] and lactation [contagious] infections
Weh is most dry mastitis noticed?
First 100d lactation
What is orbeseal?
Inert teat canal sealant prevents bacterial colonisation of ducts in dry period
How are contagious and environmental forms of mastitis spread?
contagious - in milking parlour
environmental - everywhere else but may also be spread in parlour
Are specific bacteria contagious or environmental? Give egs.
No - though some are more HOST ADAPTED [contagious]
- Strep agalactiea
- Staph areus
- Strep dysgalactiea
- Strep uberus
- E. Coli
and some more OPPORTUNISTIC [environmental]
Which type of mastitis causing bacteria (contagious or environmental) are most genetically diverse?
Where is klebsiella found?
Moist conditions environmentally, esp wood shavings and in the milk
What does a high bulk tank SCC indicate? Low SCC?
- High = contagious, low severity, majority subclinical disease
- Low = low numbers of environmental, high severity clinical disease cases
What is the national average incidence of clinical masitits cases?
35/100 cows/year [wide range]
Which area of the UK has a higher than average incidence of mastitis and why?
SE - majority of cows housed indoors on straw beds rather than pasture or cubicles
What is the most common severe, opportunistic, environmental bacterial cause of mastitis?
How may incidence of disease be >100%?
Some cows contracting infections multiple times a year
Why are low SCCs associated with more severe disease?
No innate immunity in the herd
What impacts does mastitis have for the farmer (other than cow welfare)?
- Quantitiy of milk
- Quality of milk (ABx residues, $ penalty for >200,000SCC)
- ~£100 per case lost roughly
What predisposing factor may lead to mastitis?
Poor teat score - keratitis, teat prolapse
What is the main sign seen in clinical mastitis?
Changes in milk - colour and clumps
What are the grades of mastitis?
- Grade 1: Milk change only, v yield
- Grade 2: Acute = milk changes, udder changes
Chronic = persistent form of acute
- Grade 3 = Systemically sick cow
WHat are the main bacteria involved in clinical mastitis? Which are less common agents?
- Strep agalactiae [subclin only, found only in milk]
- Strep dysgalactiae [teat injuries and ulcers, also found tonsils]
- Strep uberis [envornmental]
- Staph aureus [contagious]
- E. COli [environmental]
> Klebsiella, salmonella, yeasts, bacillus cereus, mycoplasma
How is subclinical mastitis diagnosable?
- no visable changes in milk or cow
- ^ SCC
- + CMT (Californian mastitis test)
- v milk yiled
What does the Californian milk test involve?
- Clean teat, strip
- sample, add reagent (essentially washing up liquid)
- assess for viscosity
> ^ viscosity = +
Which bacteria are responsible for chronic or sub-clinical mastitis?
- S aureus
- S uberis
- S agalctiae
Corynebacterium bovis [minor pathogen, cow wont respond as cannot casue disease - good biomarker/indication of teat clceanliness
What should be specifically looked at on clinical exam of the dairy cow?
> udder exam
- palpation (udder, teat canal, cistern)
> milk exam (before CMT) - if clotted = clinical mastitis
What are the treatment options for mastitis?
> ABx (generally broad spec eg. macrolide and penicillin)
- intramammary (DRY)
- intramammary (LACTATION)
> Oxytocin (enourage milk let down)
> fluid therapy, Ca, dextrose - support sick cow
Why should dry and lactating intramammary ABx not be mixed up?
dry = ^ withdrawal
lactating = too short an action will not be effective
Is culturing recommended for mastitis?
- clinical presentation will not differentiate causes
Usually advocated for recurrent cases, persistent infection, ^ SCC (save ££)
- freeze milk sample if farmer not wanting culture initially so can culture after if Tx fails
What are the different forms of samples that can be taken?
- bulk tank
- pooled single cow (all quarters)
- individual quarter sample (best)
> Steralise teat end, 2 pre-strips, 2ml sample in sterile container.
Do may cultures return useful results? What other assessment may be used?
- 40% sterile
- always some contamination (aim for can use PCR
- do not mix up sample containers, PCR will have preservative that kills bacteria (not good for culture!)
What type of disease do contagious organisms usually cause? HOw is this spread?
- spread cow to cow at milking
- organisms prefer linving in udder and teat skin
Give 4 main contagious bacteria associated with mastitis?
- S agalactiae (rare, found in udder only)
- S dysgalactiae (tonsils, udder, teat lesions)
- S aureus (can hide from immune system, ^ resistence -> persistnet infection and abscesses)
- (S uberis) - initially an environmental pathogen from damp straw, can spread between cows
Give 2 minor pathogens assocated with contagious mastitis
- Corynebacterium bovis
- Coagulase-Neg Staph (CNS)
-> unlikely to be pathogenic
- may be protective?
What are the 2 outcomes following infection of the udder with an environmental organism?
- rapid elimination
- serious mastitis
-> MAY persist if dry cow infected until lactation begins
How long is the dry period?
When do environmental agents usually gain entry to the udder?
What are the main and less common environmental organisms associated with mastitis?
> E Coli
- S uberis
- Klebsiella (wood shavings)
- Bacillus cereus
What cells make up SCC?
- inflammatory cells
> all milk contains some SCs
How long is the lactation period?
What SCC is seen in clinical mastitis? Sub-clinical? Fincancial penalties? Cannot go for human consumption? Target?
CLinical = millions cells/ml
Sub = >200,000 cells/ml
$$ = <100,000
What is bulk tank SCC (BMSCC) a good estimation of?
How is CONTAGIOUS mastitis controlled?
> 5 point plan
- control spread at milking time
- eliminate reservoirs of infection (Dry cow therapy, cuilling, ID subclin infected cows)
What are the 5 points of the 5 point plan?
1. prompt detection and tx of clinical cases
2. post-milking teat dip (long ating steralisation)
3. dry cow therap (ABx)
4. cull persistent offenders
5. regular service and maintainence of the milking machine (by competent person!)
How is clinical mastitis best detected?
- in milking parlour
- pre-strip teats before milking (fore-milking)
> flishes out bacteria rich milk, aids let down, check for clots
> use strip cup to prevent contamination from mimlk on floor
How may hygiene in the parlour be improved?
- individual paper towels for udder wiping pre-milking
- NO udder cloths
- wear gloves
- PRE- milking dips to improve hygiene further (short acting steralisation)
What is PMTD? What is its purpose? How can practice be improved?
Post milking teat dipping
- kills bacteria, maintains teat condition
Also keep cows standing while teat sphincters still open (30mins post milking) eg. feed
Give 4 examples of PMTDs
- chlorine based
- quaternary ammonium compounds
What is DCT? What are its aims? Is it effective?
Dry cow therapy
> LA ABx to remove existing subclin infection of dry cows (and to a lesser degree prevent further infection during dry period)
- All quarters infused with LA ABx at last milking
- More effective than lactating therapy
> Teat sealant = inert substance blocks entrance of bacteria eg. bismuth sulphate
- may cause black bits in cheese, BAD
Why may DCT lead to problems?
If cow calves early may still be within withdrawal period of drug
- can be >51d PLUS 96hrs post calving
When would cows be considered for culling? How else may they be managed?
- 3 cases of mastitis within one lactation
- persistent ^ SCC (not responsive to Tx)
> put in problem herd (milked last)
> tx at dry off
What is the target for clinical mastitis incidence?
30 cases/100 cows/year
What is the target SCC above which financial fines are imposed?
What does SCC indicate?
Prevalence (no. quarters infected on day of samping)
How can records be used to investigate mastitis?
> calculate no cases/100 cows/ year
- compare with no. ABx intramammary treatements
- if high = poor efficacy of tubes
- if low = poor compliance
> look for problem cows (>3 cases in one lactation, individual SCC high in >2 months)
What are the 3 options for treating problems cows?
2. isolate into problem herd (milk last)
3. treat - bacteriology on affected quarter, prolonged ABx
> Do not put with freshly calved cows!!
What are the 5 points of the 5 point plan?
1. early detection and immediate Tx
2.post milking teat dipping
3. dry cow ABx
4. cull offending cows
5. maintainence of milk machine
> most of these occour in the parlour
How may environmental cleanliness be assessed?
Cow cleanliness score
What does bactoscan show?
- indication of no. bacteria in milk
(replaced total bacterial count)
- mostly from contamination of milk on farm
What is the requirement and target values for bactoscan?
requirement < 20,000/ml
What are the 4 sources of bacteria in milk?
2. contamination feaces etc
3. milking machine dirty (cheesy pipes)
4. failure of refridgeration in bulk tank