1. Mastitis Organisms Contagious organisms Environmental organisms “Oddball” organisms

2. Contagious Organisms Staphylococcus aureus Streptococcus agalactiae Corynebacterium bovis Mycoplasma bovis

3. Staphylococcus aureus Invasive pathogen that causes fibrosis and abscesses/microabscesses Approx. 20% of infections become clinical Major cause of subclinical mastitis Suspected in herds with older cows, high SCC and low culling rates

4. Staphylococcus aureus Shed in low numbers from infected quarters Diagnosis by culturing requires serial samples Clinical presentation varies Chronic Staph. aureus mastitis very difficult to treat

5. Staphylococcus aureus Low cure rates for lactation treatments (10- 30%) Dry cow treatment cure rates range from 50 – 80% Some strains resistant to penicillin

6. Staphylococcus aureus Prevention – Avoid buying Staph cows – Proper function of milking machine – Good post dipping routine – Treat all quarters at dry off – Cull chronically infected cows – Milk Staph cows separately

7. Strep. agalactiae Not invasive Causes inflammation and fibrosis Clinical cases usually mild Primarily causes subclinical mastitis Bulk tank SCC highly elevated

8. Strep. agalactiae Shed in high numbers from infected gland Easy to culture from milk samples 1 infected cow in 200 will be detectable in bulk tank milk culture

9. Strep. agalactiae Sensitive to penicillin Lactational and dry cow therapy both have >90% cure rates Easily eradicated through: – Dry cow therapy or “blitz” treatment – Good hygiene – Teat dipping Prevention as for Staph. aureus

10. Mycoplasma Multiple quarter involvement with clinical mastitis Clinical cases usually severe May be a systemic phase of infection Shed in very large numbers 1 in 1,000 will cause positive BTC Requires special media for culture Suspect in herds with persistent, refractory mastitis and no growth on milk cultures

11. Coliforms Infection due to direct transfer from the environment Majority of cases in early lactation Cows more susceptible than heifers Clinical signs caused mainly by endotoxins

12. Coliforms Most infections eliminated quickly without clinical signs Some become acute clinical cases Udder is firm and swollen Milk often serous or hemorrhagic with clots Systemic illness due to toxemia

13. Coliforms Do not usually cause persistently elevated SCC Monitor by culturing milk from new clinical cases

14. Coliforms TREATMENT – Frequent stripping – Fluid i/v and oral – NSAIDs – Corticosteroids – ? Intramammary antibiotics – ? Systemic antibiotics – ? Calcium therapy

15. Coliforms PREVENTION – Need to prevent, not treat – Sanitation – Milk clean, dry udder – Vaccination

16. Environmental Streps Organisms commonly found on skin, mucous membranes and colonizing gut 50% of infections become mild clinical infections Highest incidence of new infections is in dry period

17. Environmental Streps Herd monitoring best accomplished by culturing high SCC cows and clinicals Lactational therapy – 50-60% cure with on label treatments Higher cure rates in lactation with extended therapy Dry cow therapy eliminates most existing infections

18. Environmental Streps Prevention is key Sanitation Milk clean, dry udder Predipping

19. “Oddball” organisms Coagulase negative Staphs – Hyicus, epidermidis etc – Common inhabitants of teat skin – Higher incidence in first lactation – Moderate elevation of SCC – Teat dipping, dry cow treatment are important for control

20. “Oddball” organisms Arcanobacter pyogenes – Severe clinical mastitis - “Summer Mastitis” – Abscessed quarter – Usually in heifers at pasture – Too late to treat by the time you find it

21. “Oddball” organisms Nocardia, Candida, Pseudomonas Often 2ndary to unsanitary infusion techniques or contaminated infusion products Pseudomonas often in contaminated water (check the drop hoses in the milking parlor!)

22. “Oddball” organisms Serratia marscescens – has been associated with contaminated water supplies and contaminated teat dips Bacillus spp - has been associated with contaminated antibiotic preparations and with feeding wet brewer’s grains (B. cereus)