1. MASTITIS IN THE AUSTRALIAN DAIRY INDUSTRY
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2. TABLE OF CONTENTS
1. ABOUT MASTITIS 2. A SURVEY OF MASTITIS PATHOGENS IN THE SOUTH EASTERN AUSTRALIAN DAIRY INDUSTRY 3. CLINICAL MASTITIS 4. SUBCLINICAL MASTITIS 5. ANTIBIOTIC SENSITIVITIES 6. CONCLUSION

3. ABOUT MASTITIS

4. WHAT IS MASTITIS?
MASTITIS IS THE INFLAMMATION OF THE COW’S MAMMARY GLAND, USUALLY CAUSED BY BACTERIA ENTERING THE TEAT CANAL AND MOVING TO THE UDDER. THE TWO MAIN TYPES OF MASTITIS ARE CONTAGIOUS AND ENVIRONMENTAL MASTITIS.
Contagious mastitis
Environmental mastitis
Habitat
Inside udders or on teat skin
The cow's environment
(e.g. manure, soil)
How is it spread
Contamination from infected milk
Contamination from infected environment; can be introduced with intramammary tubes if teat ends are not sterile when treatment occurs.
When is it spread
Milking time
Mainly at drying-off and around calving time; most cases seen at calving or early lactation.
Bacteria
Commonly Staph aureus and Strep agalactiae
Commonly Strep uberis, E.coli, coliforms, Pseudomonas. Many others occur occasionally.*
* Source: Countdown Downunder

5. SUBCLINICAL VS CLINICAL MASTITIS
SUBCLINICAL MASTITIS
Cow – no observable changes
Udder – no observable changes
Milk – no observable changes but significant differences in milk composition
CLINICAL MASTITIS
(CHRONIC, MILD, ACUTE, SEVERE)
Cow – spectrum from extremely unwell to no observable changes
Udder – spectrum from hot, swollen and painful to no abnormalities
Milk – displaying abnormalities from discolouration, clots, blood, clots, flakes, wateriness

6. IMPORTANCE OF MASTITIS CONTROL
Countdown Downunder has shown that every four clinical cases of mastitis cost around $1,000
These losses occur through:
Lower production
Lower payments for milk due to quality
Increased costs of treatment and culling

7. CELL COUNTS IN MILK
BULK MILK CELL COUNT (BMCC) SHOWS THE CONCENTRATION OF COW BODY CELLS IN VAT MILK.
BMCC is an Indirect measure of subclinical mastitis in the whole herd
BMCC can provide a guide of infection levels in a herd
Each 100,000 cells/mL indicates about 10% of cows are infected
Guidelines
Below 150,000 cells/mL
Excellent mastitis cell count control
150,000 – 250,000 cells/mL
Good control. Meets level for premium payment with most dairy companies
250,000 – 400,000 cells/mL
Moderate mastitis control and cell count control
Above 400,000 cells/mL
Poor / inadequate control. Milk not considered fit for human consumption
* Source: Countdown Downunder

8. MASTITIS TREATMENT ANTIBIOTIC DRY COW TREATMENT
Dry cow treatment is used to treat existing infections and reduce the number of new infections that may occur during the dry period
The most appropriate dry cow treatment strategy should be planned with a veterinarian
The choice of treatment will depend on a number of factors, including the spectrum of activity, cure rates and how long the cow has been infected
TEAT SEALANTS
Teatseal is a non-antibiotic substance which creates a physical barrier in the teat canal to prevent new intramammary infections during the dry period and reduce the incidence of clinical mastitis in early lactation
Teatseal used in combination with an intramammary dry cow antibiotic has been shown to be more effective than an intramammary antibiotic alone, reducing the rate of clinical mastitis by up to 70%

9. INTERNATIONAL CONTEXT
THE AUSTRALIAN DAIRY INDUSTRY IS RECOGNISED FOR ITS RESPONSIBLE USE OF ANTIBIOTIC TREATMENTS
Internationally, the responsible use of antibiotics to treat mastitis has proven to be a greater challenge
After European policy makers expressed concern over the link between antibiotic use in livestock and antibiotic resistance in humans, the Netherlands took its own stance and, in 2012, introduced penalties for failing to reduce on-farm antibiotic use including:
Targeting 50% reduction in use
New farm protocols in place, aimed at prevention
Antibiotics used primarily for treatment rather than prophylactically

10. JUDICIOUS USE
JUDICIOUS USE IS IMPORTANT TO MINIMISE THE DEVELOPMENT OF RESISTANCE WHILE MAINTAINING EFFECTIVENESS TO PREVENT DISEASES
Requires an understanding of pathogens involved
Need to assess any changes in antimicrobial sensitivities over time

11. A Survey of Mastitis Pathogens in the South Eastern Australian Dairy Industry

12. WHY CONDUCT A MASTITIS SURVEY IN AUSTRALIA?
Farmers often make the comment
“We need new antibiotics to treat mastitis because the bacteria are resistant to the ones we currently have”
Farmers often ask the question
“Do I need different antibiotics for different stages of lactation, different ages or different regions?”
Farmers will also question their vet
“Is this type of bacteria the standard cause of mastitis in Australia or is something different happening on my farm?

13. SURVEY OBJECTIVES
Determine the prevalence of clinical and subclinical mastitis pathogens in key dairy producing regions Investigate the impact that seasons, stage of lactation and lactation number have on mastitis pathogen prevalence Identify the current antibiotic sensitivity patterns for Australia’s most costly pathogens in dairy cattle Understand the relevance of currently available treatment options used in clinical and subclinical mastitis therapy 1 2 3 4

14. ABOUT THE SURVEY SURVEY SAMPLES
Australia’s largest study into the prevalence of mastitis pathogens in local milk producing regions, including:
13 veterinary practices
65 farms
2986 clinical mastitis samples over 13 months
1038 subclinical mastitis samples
All positive cultures submitted for culture and sensitivity (CLSI approved standards)
All positive cultures archived
SURVEY DESIGN
Herd size: > 464 ( ) cows in milking herd
Mean BMCC in previous year of 100, ,000
Herd testing on regular basis (minimum four tests per year) and maintain electronic herd health recording system
Met acceptable animal welfare standards
Project fully funded by Zoetis in 2010
Collaborated with Dairy Focus to run the survey throughout 2011 and early 2012

15. CLINICAL MASTITIS

16. OVERALL CLINICAL MASTITIS CULTURE RESULTS
% of pathogens isolated

17. OVERALL CLINICAL MASTITIS CULTURE RESULTS
OVERALL, 39.3% OF SAMPLES WERE EITHER CONTAMINATED (16.1%) OR PRODUCED NO GROWTH (23.2%)
With the contaminated and no growth samples excluded the major pathogens are:
54.3% Strep. uberis
14.8% Staph. aureus
11.7% E. coli
8.9% Strep. dysgalactiae
Total %

18. WHAT DO THESE RESULTS MEAN AT THE FARM LEVEL?
One in six samples were contaminated at the time of collection
Farmers were trained and supplied with all consumables required to collect samples aseptically
If contaminating bacteria are still present on the teat orifice at the time of collection - they would still be present at the time the antibiotic treatment was infused
If a cow is treated with three tubes of intramammary antibiotics per case of mastitis, she will have a 50% chance of receiving a new infection due to poor hygiene!
Important to treat the existing infection and not to introduce a new infection

19. WHAT DO THESE RESULTS MEAN AT THE FARM LEVEL?
54.3% Strep. uberis – environmental contaminant
14.8% Staph. aureus – cow associated bacteria
11.7% E. coli – environmental contaminant
8.9% Strep. dysgalactiae – cow associated bacteria
The big four bacteria cause the majority of mastitis – no new super bacteria have emerged
Environmental bacteria have taken over from cow-associated bacteria as the leading cause of mastitis

20. CLINICAL MASTITIS Stage of lactatioN

21. CLINICAL MASTITIS VS STAGE OF LACTATION
MAJOR PATHOGENS ISOLATED DURING LACTATION
OUTCOMES
The stage of lactation appears to have little impact on the frequency of the major bacteria
Strep. uberis was the dominant pathogen at all stages of lactation and was consistently isolated at a rate greater than 30%

22. CLINICAL MASTITIS GEOGRAPHICAL REGION

23. CLINICAL MASTITIS VS GEOGRAPHICAL REGION
MAJOR PATHOGENS ISOLATED BY REGION

24. CLINICAL MASTITIS VS GEOGRAPHICAL REGION
MINOR PATHOGENS ISOLATED BY REGION

25. CLINICAL MASTITIS VS GEOGRAPHICAL REGION
Regional differences were minor
Western District of Victoria recorded the highest incidence of Strep. uberis at 36.8%, Gippsland recorded lowest at 27.5%
Except
Staph. aureus was recorded at 12.7% of cultures from Gippsland, but only 4.5% of cultures from Northern Victoria
E. coli was the second most likely pathogen in samples from Northern Victoria at an isolation rate of 9.7%
C. bovis was isolated at a rate of around 1.5% for the mainland states, yet only a single isolate in Tasmania

26. CLINICAL MASTITIS NUMBER OF LACTATIONS

27. CLINICAL MASTITIS VS NUMBER OF LACTATIONS
MAJOR PATHOGENS ISOLATED BY LACTATION NUMBER
OUTCOMES
Heifers produced the highest rate of Strep. uberis infections; to manage this:
Maintain a clean environment for calving
Introduce a teat sealant
Cows had broadly similar rates of infection with the major bacteria regardless of their age – similar treatment strategies will apply to all age groups

28. SUBCLINICAL MASTITIS

29. SUBCLINICAL MASTITIS RESULTS
SUBCLINICAL MASTITIS PATHOGENS ISOLATED
IMPORTANT FINDINGS
On a single occasion on some of the enrolled farms, a further samples were collected from a selected group of cows that displayed a high somatic cell count in mid-to-late lactation
No growth result for the subclinical mastitis samples (17.4%) was broadly similar to the rate calculated for the clinical mastitis samples (23.2%)
The frequency with which a contaminated sample was submitted from cows with subclinical mastitis (40.7%) was far higher than for clinical mastitis submissions (16.1%)

30. CONTAMINATED SAMPLES - IMPLICATIONS
WHY DO WE SEE HIGHER RATES OF CONTAMINATION WHEN COLLECTING A COMPOSITE SAMPLE FROM FOUR QUARTERS?
The sterility of the four collectors is not maintained
Sampling cows rather than a single cow
The sampling is conducted at the end of milking when more manure is present in the environment
Sampling is seen as just ‘another job’ at the end of the milking session – a time when attention to detail may not be a priority
These cows will receive DCT shortly after this sampling procedure (antibiotics +/- teat sealant)
The antibiotics commonly used will not necessarily cure the environmental bacteria that may be infused into the udder if hygiene is poor
Significant time and money is invested in applying DCT - the ROI is dependent on strict hygiene

31. SUBCLINICAL MASTITIS RESULTS
SUBCLINICAL MASTITIS MAJOR BACTERIA
IMPORTANT FINDINGS
Staph. aureus was the organism most frequently isolated from subclinical mastitis samples (17.5%)
Strep. uberis returned 141 positive cultures (13.1%)
E. coli was only cultured on 10 occasions (0.9%) from the samples submitted from high ICCC cows
Regional differences were minor; Staphs and Streps were the predominant organisms likely to be present in a high ICCC cow at the time of drying off
Data excludes no growth and contaminated samples

32. ANTIBIOTIC SENSITIVITIES

33. CLINICAL MASTITIS SAMPLES
STREP UBERIS

34. CLINICAL MASTITIS SAMPLES
STAPH AUREUS

35. CLINICAL MASTITIS SAMPLES
E COLI

36. CLINICAL MASTITIS SAMPLES
STREP DYSGALACTIAE

37. SUBCLINICAL MASTITIS SAMPLES
STAPH AUREUS

38. SUBCLINICAL MASTITIS SAMPLES
STREP UBERIS

39. SUBCLINICAL MASTITIS SAMPLES
STREP DYSGALACTIAE

40. SUBCLINICAL MASTITIS SAMPLES
CLOXACILLIN SENSITIVITY

41. CONCLUSION

42. SUMMARY A RESULT THE DAIRY INDUSTRY CAN BE PROUD OF
Cloxacillin has been the most commonly used antibiotic in Australia for treating mastitis over a 35 year period
The Staphs and Streps responsible for the clinical cases of mastitis in this survey were all still 100% sensitive to this antibiotic – a remarkable result given the time this antibiotic has been used
Australian vets and producers can confidently say they have been using antibiotics responsibly

43. THE FUTURE
THE BACTERIA CAUSING MASTITIS IN OUR HERD IN 2013 ARE STILL HIGHLY SENSITIVE TO THE ANTIBIOTICS WE CURRENTLY HAVE REGISTERED IN AUSTRALIA
Producers may need to take more care in the application of these antibiotics to improve cure rates – focus on hygiene, administration technique and ensure 100% compliance with full course of treatment
The industry may need to investigate new ways of using existing antibiotics to achieve higher cure rates, for example:
Extended treatment strategies
Different formulations
Earlier detection of clinical mastitis and prompt treatment strategies may also enhance the effectiveness of the antibiotic arsenal