Mastitis Flashcards
Describe the difference between clinical and sub clinical mastitis.
Clinical results in clinical signs - changes in milk, udder and cow.
Subclinical results in no clinical signs - changes in SCC, milk quality and yield
Describe the grading system of clinical mastitis.
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
Describe the consequences of mastitis infection.
Infection cleared
Chronically sisters infection - spreads within herd
Reduced milk yield and permanent udder damage
Death - involuntary culling
Name some of the factors which can predispose cows to mastitis.
Genetics Nutrition Stage of lactation - dry period (less likely) Vaccination Stress Poor management
How do mastitis pathogen enter the udder?
Bacteria enter the teat through the open canal
How long after milking do teat canals remain open?
20-30 mins
Why would milk let down occur before milking begins?
Conditioning
How can bacteria be incorporated into the drying off cows udder?
The keratin plug which forms traps bacteria within the udder at drying off.
Describe the difference between contagious and environmental mastitis pathogens.
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
Name the three main mastitis pathogens in the uk.
Staph aureus
Strep uberis
Coliforms - E. coli, klebsiella pneum
Staph aureus
Contagious or environmental
Contagious
Strep agalactiae
Contagious or environmental
Contagious
Strep dysgalactiae
Contagious or environmental
Contagious
Mycoplasma
Contagious or environmental
Contagious
Step uberis
Contagious or environmental
Generally environmental but some contagious adapted strains
Ecoli
Contagious or environmental
Environmental
Describe three methods of bacterial identification of mastitis pathogens.
Culture and sensitivity - alive bacteria only
Per - detects alive or dead bacteria
Pattern detection
Chronically high SCC in individual cows, herds.
Suggests which type of bacteria?
Gram positive
Quick spike in SCC and quick recovery.
Suggests which type of bacteria?
Gram negative
A SCC or CM in the first months post calving.
Suggests infection picked up when?
Dry period
Good low herd SCC but lots of clinical mastitis.
Suggests which type of bacteria.
Gram negatives
Describe the morphology and test findings associated with Staph aureus?
Gram positive cocci
Coagulase positive
Causes hemolysis on blood agar
Where on and off the cow could staph aureus be found?
Mammary gland, tear skin, tonsils, vaginal and millers hands
Describe the fomite sources of contagious mastitis.
Clusters, hands, udder cloths, heifers pre-calving teat sucking.
Which bacteria is able to persist intracellularly in the cow and is therefore difficult for the cows immune system to clear without ABs?
Staph aureus
How does staph aureus cause abscesses?
Damage to the duct system leads to deep pockets of infection in secretory system.
Describe three of the virulence factors which are use by staph aureus?
Cell wall protein A prevents neutrophil recognition
Survive in keratin in teat canal
Survives intracellularly and can multiply in phagocytes
Why is staph aureus a difficult mastitis type to treat?
Difficult to detect due to being intracellular
Udder fibrosis and abscessation make treatment difficult
Can be pen resistant
Ab response is difficult
Describe a treatment plan for staph aureus mastitis?
During lactation - recommend long duration of treatment, intramammary and systemic
Dry off and treat
Cull chronic
Dry off affected quarter
What factors decrease the chance of curing clinical staph aureus mastitis?
Older cows > 5 lactations
Three or more repeated infections
Chronic increase in SCC
Penicillin resistance
What antibiotic would commonly be chosen in cases of penicillin resistant staph aureus?
Cloxacillin tube and tylosin systemically
Describe the morphology of strep agalactiae
Gram positive cocci
Non haemolytic
Very small colonies
What clinical signs are associated with strep agalactiae?
Subclinically high SCC
Grade 1-2 mastitis
No systemic illness
Treatment for streptococcus agalactiae?
Beta lactam
Improved parkour hygiene!
Describe the morphology and culture findings of streptococcus dysgalactiae.
Gram positive coccus
Edwards medium - small colonies
Alpha haemolysis
Name two mycoplasma species which can cause mastitis?
M Bovis
M californicum
True or false.
Mycoplasma is highly contagious.
True - it is also difficult to treat since the cells lack cell wall and are therefore not a target for beta lactams
Describe the appearance of “milk” from a cow infected with mycoplasma.
Very thick - yoghurt-like
Describe the pathogenicity of mycoplasma in clinical mastitis?
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
How long can cows shed mycoplasma for?
Months or years
CNS
Coagulase negative staphylococci
CNS can be identified as a mastitis pathogen but why is it always prudent to query positive results?
May occur due to teat skin contamination
Describe the shedding pattern of staph aureus.
Intermittent and cyclic - if culture is negative then re sample
Describe the morphology and culture findings associated with E. coli.
Creamy white colonies on blood agar
Haemolytic and non haemolytic forms
Gram negative rods
Describe the pathogenesis of environmental mastitis caused by E. coli.
LPS endotoxin damages vascular and secretory tissue.
How can endotoxaemia caused by E. coli be treated?
Stripping out the affected quarter.
Which grade of E. coli mastitis is the most common ?
Grade 3
Describe the treatment of grade 1-2 and grade 3 mastitis?
Grade 1-2 = self cure (intra-mammary antibiotics)
Grade 3 = strip out affected quarter (oxytocin), iv and systemic antibiotics (PS or oxytet), NSAIDs, IVFT
How could you control E. coli mastitis on farm?
Times of importance - dry period and early lactations proved hygiene PMTD Controlled loafing time - ensure eating Appropriate dry cow therapy Vaccination - only reduces
Describe the morphological and culture findings associated with strep uberis.
Non-haemolytic
Brown colonies on Edwards
Gram positive cocci
Bovine faeces, straw yard housing and straw cubicles are associated with which mastitic pathogen.
Strep uberis
How does strep uberis cause disease and persist in the udder?
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
Describe the treatment plan for strep uberis mastitis.
Prolonged penicillin intramammary courses
Penethamate a penicillin ester which improves penetration
Intracellular ab - macrolides
Cull chronic
Name three other environmental mastitis pathogens and the management practices they are associated with.
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,
Which herd members are often associated with summer mastitis?
Outdoor heifers, dry cows
Which pathogens and vector ectoparasite are associated with summer mastitis?
H irritans
T pyogenes, peptococcus indolicus, strep dysgalactiae, bacteria des melaninogenicus, fusiforms necrophorum
Describe the clinical signs associated with summer mastitis.
Hot, hard swollen painful udder
Thick purulent secretion
Lame or systemic illness
Blind teat end when cow comes into milk
How can summer mastitis be treated and controlled?
Treatment - systemic antibiotics or amputation of the affected quarter
Control - fly control, remove affected from the group, increase freq of dry cow therapy
Which pathogen does start vac protect against?
Staph aureus, coli forms, CNS
What is mastitis?
Inflammation of mammary gland
