Mastitis

Question 1

Describe the difference between clinical and sub clinical mastitis.

Answer 1

Clinical results in clinical signs - changes in milk, udder and cow.
Subclinical results in no clinical signs - changes in SCC, milk quality and yield

Question 2

Describe the grading system of clinical mastitis.

Answer 2

1 Mild - changes in milk
2a Acute - changes in milk, hot, painful udder
2b Chronic - changes in milk, hard and lumpy udder
3 - changes in milk, udder, sick cow

Question 3

Describe the consequences of mastitis infection.

Answer 3

Infection cleared
Chronically sisters infection - spreads within herd
Reduced milk yield and permanent udder damage
Death - involuntary culling

Question 4

Name some of the factors which can predispose cows to mastitis.

Answer 4

Genetics
Nutrition
Stage of lactation - dry period (less likely) 
Vaccination
Stress 
Poor management

Question 5

How do mastitis pathogen enter the udder?

Answer 5

Bacteria enter the teat through the open canal

Question 6

How long after milking do teat canals remain open?

Answer 6

20-30 mins

Question 7

Why would milk let down occur before milking begins?

Answer 7

Conditioning

Question 8

How can bacteria be incorporated into the drying off cows udder?

Answer 8

The keratin plug which forms traps bacteria within the udder at drying off.

Question 9

Describe the difference between contagious and environmental mastitis pathogens.

Answer 9

Contagious are obligatory - they must live on the cow - spread from cow to cow.
Environmental - live in slurry, bedding, soil etc - infection occurs when teats come into contact with contaminated material

Question 10

Name the three main mastitis pathogens in the uk.

Answer 10

Staph aureus
Strep uberis
Coliforms - E. coli, klebsiella pneum

Question 11

Staph aureus

Contagious or environmental

Answer 11

Contagious

Question 12

Strep agalactiae

Contagious or environmental

Answer 12

Contagious

Question 13

Strep dysgalactiae

Contagious or environmental

Answer 13

Contagious

Question 14

Mycoplasma

Contagious or environmental

Answer 14

Contagious

Question 15

Step uberis

Contagious or environmental

Answer 15

Generally environmental but some contagious adapted strains

Question 16

Ecoli

Contagious or environmental

Answer 16

Environmental

Question 17

Describe three methods of bacterial identification of mastitis pathogens.

Answer 17

Culture and sensitivity - alive bacteria only
Per - detects alive or dead bacteria
Pattern detection

Question 18

Chronically high SCC in individual cows, herds.

Suggests which type of bacteria?

Answer 18

Gram positive

Question 19

Quick spike in SCC and quick recovery.

Suggests which type of bacteria?

Answer 19

Gram negative

Question 20

A SCC or CM in the first months post calving.

Suggests infection picked up when?

Answer 20

Dry period

Question 21

Good low herd SCC but lots of clinical mastitis.

Suggests which type of bacteria.

Answer 21

Gram negatives

Question 22

Describe the morphology and test findings associated with Staph aureus?

Answer 22

Gram positive cocci
Coagulase positive
Causes hemolysis on blood agar

Question 23

Where on and off the cow could staph aureus be found?

Answer 23

Mammary gland, tear skin, tonsils, vaginal and millers hands

Question 24

Describe the fomite sources of contagious mastitis.

Answer 24

Clusters, hands, udder cloths, heifers pre-calving teat sucking.

Question 25

Which bacteria is able to persist intracellularly in the cow and is therefore difficult for the cows immune system to clear without ABs?

Answer 25

Staph aureus

Question 26

How does staph aureus cause abscesses?

Answer 26

Damage to the duct system leads to deep pockets of infection in secretory system.

Question 27

Describe three of the virulence factors which are use by staph aureus?

Answer 27

Cell wall protein A prevents neutrophil recognition Survive in keratin in teat canal Survives intracellularly and can multiply in phagocytes

Question 28

Why is staph aureus a difficult mastitis type to treat?

Answer 28

Difficult to detect due to being intracellular Udder fibrosis and abscessation make treatment difficult Can be pen resistant Ab response is difficult

Question 29

Describe a treatment plan for staph aureus mastitis?

Answer 29

During lactation - recommend long duration of treatment, intramammary and systemic Dry off and treat Cull chronic Dry off affected quarter

Question 30

What factors decrease the chance of curing clinical staph aureus mastitis?

Answer 30

Older cows > 5 lactations Three or more repeated infections Chronic increase in SCC Penicillin resistance

Question 31

What antibiotic would commonly be chosen in cases of penicillin resistant staph aureus?

Answer 31

Cloxacillin tube and tylosin systemically

Question 32

Describe the morphology of strep agalactiae

Answer 32

Gram positive cocci Non haemolytic Very small colonies

Question 33

What clinical signs are associated with strep agalactiae?

Answer 33

Subclinically high SCC Grade 1-2 mastitis No systemic illness

Question 34

Treatment for streptococcus agalactiae?

Answer 34

Beta lactam | Improved parkour hygiene!

Question 35

Describe the morphology and culture findings of streptococcus dysgalactiae.

Answer 35

Gram positive coccus Edwards medium - small colonies Alpha haemolysis

Question 36

Name two mycoplasma species which can cause mastitis?

Answer 36

M Bovis | M californicum

Question 37

True or false. | Mycoplasma is highly contagious.

Answer 37

True - it is also difficult to treat since the cells lack cell wall and are therefore not a target for beta lactams

Question 38

Describe the appearance of "milk" from a cow infected with mycoplasma.

Answer 38

Very thick - yoghurt-like

Question 39

Describe the pathogenicity of mycoplasma in clinical mastitis?

Answer 39

LPS stimulates hosts immunity and causes epithelial degeneration, outpouring of leukocytes which causes abscess formation, alveolar hypertrophy, fibroplasia around ducts. This leads to destruction of the affected quarter

Question 40

How long can cows shed mycoplasma for?

Answer 40

Months or years

Question 41

CNS

Answer 41

Coagulase negative staphylococci

Question 42

CNS can be identified as a mastitis pathogen but why is it always prudent to query positive results?

Answer 42

May occur due to teat skin contamination

Question 43

Describe the shedding pattern of staph aureus.

Answer 43

Intermittent and cyclic - if culture is negative then re sample

Question 44

Describe the morphology and culture findings associated with E. coli.

Answer 44

Creamy white colonies on blood agar Haemolytic and non haemolytic forms Gram negative rods

Question 45

Describe the pathogenesis of environmental mastitis caused by E. coli.

Answer 45

LPS endotoxin damages vascular and secretory tissue.

Question 46

How can endotoxaemia caused by E. coli be treated?

Answer 46

Stripping out the affected quarter.

Question 47

Which grade of E. coli mastitis is the most common ?

Answer 47

Grade 3

Question 48

Describe the treatment of grade 1-2 and grade 3 mastitis?

Answer 48

Grade 1-2 = self cure (intra-mammary antibiotics) | Grade 3 = strip out affected quarter (oxytocin), iv and systemic antibiotics (PS or oxytet), NSAIDs, IVFT

Question 49

How could you control E. coli mastitis on farm?

Answer 49

``` Times of importance - dry period and early lactations proved hygiene PMTD Controlled loafing time - ensure eating Appropriate dry cow therapy Vaccination - only reduces ```

Question 50

Describe the morphological and culture findings associated with strep uberis.

Answer 50

Non-haemolytic Brown colonies on Edwards Gram positive cocci

Question 51

Bovine faeces, straw yard housing and straw cubicles are associated with which mastitic pathogen.

Answer 51

Strep uberis

Question 52

How does strep uberis cause disease and persist in the udder?

Answer 52

Hides in mammary epithelial cells to avoid immune detection Adhesion molecules attach mammary epithelium Hyaluronic acid capsule may prevent ab or neutrophil attachment May resist phagocytosis killing Inhibits PMN pseudopodia production

Question 53

Describe the treatment plan for strep uberis mastitis.

Answer 53

Prolonged penicillin intramammary courses Penethamate a penicillin ester which improves penetration Intracellular ab - macrolides Cull chronic

Question 54

Name three other environmental mastitis pathogens and the management practices they are associated with.

Answer 54

Klebsiella - sawdust, dirty parlour, acute mastitis Bacillus cereus and lichens forms - Brewers grain, dirty parlour wash, acute Pseudomonas - sawdust bed, poor hygiene Yeasts - wet mouldy bedding,

Question 55

Which herd members are often associated with summer mastitis?

Answer 55

Outdoor heifers, dry cows

Question 56

Which pathogens and vector ectoparasite are associated with summer mastitis?

Answer 56

H irritans | T pyogenes, peptococcus indolicus, strep dysgalactiae, bacteria des melaninogenicus, fusiforms necrophorum

Question 57

Describe the clinical signs associated with summer mastitis.

Answer 57

Hot, hard swollen painful udder Thick purulent secretion Lame or systemic illness Blind teat end when cow comes into milk

Question 58

How can summer mastitis be treated and controlled?

Answer 58

Treatment - systemic antibiotics or amputation of the affected quarter Control - fly control, remove affected from the group, increase freq of dry cow therapy

Question 59

Which pathogen does start vac protect against?

Answer 59

Staph aureus, coli forms, CNS

Question 60

What is mastitis?

Answer 60

Inflammation of mammary gland