Therapeutics (Yr 4)

Question 1

do mastitis cases self cure?

Answer 1

depends on type of bacteria - gram negative organisms can

Question 2

how long is a traditional dry period?

Answer 2

60 days (can be as low as 40)

Question 3

why does the duration of activity of dry cow therapies differ?

Answer 3

formulation and base of product

Question 4

what is the point of dry cow therapy?

Answer 4

clear persistent infections (sub-clinical, intracellular, high cell count)
protect against new infections (infections postpartum, summer mastitis)

Question 5

what mastitis pathogen survives intracellularly?

Answer 5

Staphylococcus aureus

Question 6

what bacteria are involved in summer mastitis?

Answer 6

Arcanobacter pyogenes (necrosis)
Peptococcus indolicus (foul smell)
Streptococcus dysgalactia

Question 7

are there any disadvantages of dry cow therapy?

Answer 7

cell counts too low (possible risk of toxic mastitis)
risk of introducing new infections during applications
possible antibiotic resistance

Question 8

what is the substance used at teat sealant?

Answer 8

bismuth subnitrate

Question 9

what does the teat sealant ubroseal blue contain?

Answer 9

bismuth substrate and a blue dye (so you can tell if it has been fully stripped out)

Question 10

how can you decide the cows for selective dry cow therapy?

Answer 10

bacteriology
SCC
California milk test to check for no infection since milk recording
check for teat end damage

Question 11

why is bacteriology not good for selecting cows for dry cow therapy?

Answer 11

expensive
Staphylococcus aureus is intermittently shed

Question 12

what is the cut off used for SCC when selecting for dry cow therapy?

Answer 12

<200 000 cell/ml
(<125 000 cell/ml in lactation heifers)

Question 13

what is the problem of not fully stripping out sealant when milking?

Answer 13

bismuth substrate reacts with hydrogen sulphide in maturing cheese to create a black spot

Question 14

what is the protocol for intra-mammary tube application?

Answer 14

after milking and cleaning parlour
clean gloves/wash between cows
pre-dip and allow 30 seconds kill time
surgical spirit and cotton wool until clean
post dip afterwards
allow loafing before going to bedding
recheck daily (reduce feed to reduce milk)

Question 15

what are the long acting intra-mammary tubes called?

Answer 15

…. xtra

Question 16

what are cloxacillin +/- ampicillin dry cow tubes aimed at treating?

Answer 16

Staphylococcus aureus (then broaden)

Question 17

what are the main types of dry cow antibiotic tube?

Answer 17

cloxacillin
penicillin
cephalosporins

Question 18

what is added to the penicillin dry cow tubes?

Answer 18

framycetin, penethamate

Question 19

what is framycetin?

Answer 19

active part of neomycin, which has gram negative effects

Question 20

what is penethamate used for in dry cow antibiotic tubes?

Answer 20

penicillin ester that gets into cells to attack Streptococcus uberus or Staphylococcus aureus

Question 21

what is required to use cefquinome based dry cow tubes?

Answer 21

culture and sensitivity (it is a CIA)

Question 22

how long is the milk withhold for dry cow tubes after calving?

Answer 22

about 96 hours (some 156)

Question 23

how effective is tylosin and tilmicosin as a dry cow therapy?

Answer 23

research suggests efficiency is poor

Question 24

why may mastitis treatments fail?

Answer 24

antibiotic resistance
bacterial dormancy
L-forms (insensitive to beta-lactams as don’t have a cell wall at this stage)
biofilms
reduced host response (steroid, stress…)
reduced phagocytosis (consequence of some antibiotics)
re-infections from external source, teat-canal infections, uncleared udder

Question 25

why may antibiotics not reach the site of infection in adequate concentrations?

Answer 25

too low dose
too long dose interval
too short treatment period

Question 26

what are the pharmokinetic limitations that could lead to mastitis treatment failures?

Answer 26

absorption, disposition, elimination
sequestration due to ionisation
diffusion barriers (oedema, abscesses, fibrosis)
poor delivery across blood/milk barrier in systemic treatment
if antibiotic binds to milk/serum
intracellular pathogens

Question 27

should fluroquinolones be used for mastitis?

Answer 27

no (shouldn’t be used)