Mastitis therapeutics Flashcards
Traditionally how long is the dry cow period?
- 60 days
Whats the benefit of using cloxacillin + ampicillin together?
- Cloxacillin = gram +ve
- Ampicilllin = Gram -ve
(Bovaclox)
When would you use dry cow therapy?
- Clear persistent infections =
-sub-clinical
-Staph aureus - intracellular location
-High cell count cows
What does protect against new infection include?
- Acute enterobacteriacae infection post-partum = E.coli, Klebsiella, Serratia
- Summer mastitis - A. pyogenes, Strep dysgalactiae
What are disadvantages of dry cow therapy?
- Lower cell count = more likely to get acute mastitis
- Hygiene during application = new infections?
- Spectrum of product to protect against enterobacteriacae infections acquired during dry period
- Treat 100% of quarters to protect 15%
- Antibiotic resistance
- Expensive
- Farm assurance schemes - organic schemes
How does orbeseal work?
- Remains as a paste within the base of the teat cistern and teat canal until stripped out at calving
- Remain in situ for the entire length of the dry period even in dry periods of up to 100 days
Which cows would you select for selective dry cow therapy?
– Bacteriology – expensive & Staph intermittently shed
– SCC < 200,000 cell/ml in cows / < 125,000 cell/ml in 1st lactation heifers?
* AND no clinical case in this lactation (or last 3 months)
* Lower limit under which cows given AB for protection?
* CMT before drying off if SCC not measured recently
* Check teat ends to ensure not damaged =>AB?
* Start with 25% of eligible cows and gain confidence
* Hidden cost – management & risk
* If not sterile then cows will get sick (and could die!) a few days after infusion
What are problems with sealant?
- Black spots in cheese
– Bismuth subnitrate + hydrogen sulphide from maturing cheese = bismuth sulphide
– Farmer trained to apply sealant and not massage the udder
– Removal of sealant residues by centrifuging milk - Risk of infection if not instilled in a “surgically” sterile fashion
- Newer “me too” products have limited clinical efficacy data prior to authorisation
- Ubroseal being reformulated with blue dye so can see if it has been stripped out
How would you target mastitis?
- Target staph aureus first then broaden out =
- Cloxacillin (orbenin)
- Cloxacillin + Ampicillin (Boviclox)
What is penicillin effective against?
Strep uberis
What is management of drying off?
- Set dry period – management decision – early / late
- Batch dry off – get organised, identify cow, less mistakes
- Abrupt – intermittent milking - cell counts increase
- Cow should not go through parlour again – milk let down = risk of antibiotic in milk
What are other Tx at drying off?
- Tylosin
- Tilmicosin (Micotil)
- Other longer acting macrolides
When would you not treat mastitis?
- Some culture negative
- Some due to yeast
- Some will self-cure
- Some farms using on farm culture systems and not treating mild gram –ve infections during lactation – e.g. Vetorapid, AccuMast
- Developing area – keep an eye on it
What can cause mastitis treatment failure?
- Antibiotic resistance
- Bacterial dormancy (treatment duration = 10 life cycles)
- L-forms - naked so insensitive to beta-lactams
– formation suppressed by novobiocin - Biofilms
- Reduced host response – steroids, stress
- Reduced phagocytosis (novobiocin)
- Re-infections =
– from un-cleared udder infections
– from teat-canal infections (nozzles)
– from external sources - AB’s do not reach the site of infection in adequate concentrations due to =
– too low a dose
– too long a dose interval
– too short a treatment period
What is E.coli mastitis sensitive to?
- Amoxicillin
- Enrofloxacin
- Neomycin
- Some sensitivity to penicillin + streptomycin
