1. Mastitis
Simon Kenyon

2. Udder anatomy

3. Udder anatomy

4. Allometric Growth

6. Economic Impact 40% of morbidity on dairy farms
Most costly cattle disease in the US
Estimated cost to the industry greater than 2 billion dollars/yr
Estimated to cost $ /cow
For herd-based worksheet:

7. Mastitis Classification
Mastitis caused by a wide variety of microbial agents
Classified as:
Clinical
Subclinical
Also classified as:
Contagious
Environmental

12. Subclinical mastitis No visible changes in the milk
Elevated somatic cell counts
Normal milk has less than 200,000 SCC/ml
Most common form of mastitis
National Mastitis Council estimate:
15-40 cases of subclinical mastitis for every 1 case of clinical mastitis

13. Economic Impact 70% of loss due to decreased production
Remaining losses due to:
Lost premiums
Treatment costs
Discarded milk
Death/Culling
Veterinary expenses
Cost of violative antibiotic residues

14. Economic Impact

15. Contagious vs Environmental
Strep. agalactiae
Staph. aureus
Corynebacterium bovis
Mycoplasma
Environmental
Environmental Streps
Strep uberis
Strep. dysgalactiae
Coliforms
E.coli
Klebsiella

16. Contagious vs Environmental
Transmitted during milking
Control
Parlor hygiene
Machine function
Post-dip
Dry cow Rx
Environmental
Transmitted in the environment or during milking
Control
Cow environment
Udder prep.
Health of teat end
Dry cow Rx

21. Pulsation System Graph
0.6 sec
0.4 sec

23. Contagious Mastitis Spread from cow to cow.
Bacteria must live in udder tissue or on skin
Organisms are transferred during the milking process
Major impact is as cause of subclinical mastitis

25. Environmental Mastitis
Organisms spread from environment to cow
Spread may occur between milkings or during milking
Include some of the common causes of clinical mastitis as well as subclinical infections

26. Teat ends Vacuum level Liner tension Liner condition Overmilking
Response to mechanical stress or irritation of the teat end is hyperkeratosis

28. S N R VR

29. Risk factors for hyperkeratosis
Long pointed teats
Slow milking
High producing cows
Stage of lactation
Parity
Weather conditions
Chemical irritation
Cluster removal time
Mein et al. 2001

30. Recommendations Particular attention to cleaning teat ends
D (massage) phase at least 250 ms
Cluster removal when milk flow reaches 1 lb/min
Teat skin in good condition
Follow recommendations:
Vacuum levels
Liner bore
Liner length and tension
Liner replacement schedules

31. Hyperkeratosis and Disinfection
Score
Treatment
Ave. SCC
Significance
Low
Disinfected
Non-treated
126,000
178,000 NS
Medium
142,000
306,000
P <.01
High
157,000
412,000
Gleeson et al. 2004

32. Risk of New Infections Dry Milking Calving Environmental Streps
Contagious mastitis
Coliforms
Str. uberis
Str. dysgalactiae
Dry
Milking
Calving

33. Dry cows

41. Back Flush System

42. Mastitis Diagnosis Physical examination DHIA reports/SCC reports
Strip Cup
CMT
Milk conductivity
Bacterial culture
On farm observation

43. Clinical Mastitis
M1 - Changes in the milk (Clots, flakes, clumps, or discoloration)
M2 – Changes in the milk + udder swelling, heat or pain
M3 – Changes in the milk + udder changes + systemic illness

45. Mastitis Treatment Treat clinicals during lactation
Treat subclinicals at dry off
Dry treat every quarter of every cow
Coliform infections – supportive therapy +/- antibiotics
ALWAYS CORRECT THE MANAGEMENT FLAW

51. Antibiotic Choice
Use proprietary intramammary products as primary treatment
Systemic antibiotics may be used as adjunct treatment (ampicillin or penicillin)
Avoid aminoglycosides e.g gentamycin (meat withdrawal 6 –18 months)
Mycotil milk withdrawal is 15 – 21 days
Naxcel/Excenel systemically does not reach therapeutic levels in the udder

52. Herd Investigation Examine records Individual cow somatic cell counts
Samples for bacteriology
Individual cow samples
Quarter samples
Evaluate parlor procedures
Milking machine evaluation
Look at the dry cows!

53. Somatic Cell Counts No infection in quarter: 50 – 100,000 SCC
Infected quarters: SCC 250,000+
In small herds a few cows may be responsible for high percent of BTSCC
Compare Linear Score and actual BTSCC
BTSCC LS
Few infected
600,000
3.1
Many infected
4.5

54. Milk loss vs linear score

55. Average LS versus average SCC

56. Bulk Tank Cell Counts Cow # Linear Score SCC 1 2.5 50,000 2 3 4 5 6 7
8.0
3,000,000
3.8
540,000
If btscc was at 540,000 because all cows were at 540,000 then SCR would be 5.8

57. Individual cow SCCs for two herds with same herd average SCC

63. Culturing Individual quarter samples CMT positive quarter samples
16 samples from 16 CMT positive cows
Sample as they come through the parlor
Do not specially select problem clinical cases

64. Interpretation of Culture Results
Strep. agalactiae – always significant
Staph. aureus – underestimates number of infected cows
If 3 or more Staph. aureus - culture the whole herd
Environmental Streps. – easy to grow, often significant
Coliforms – occasional chronic cows

65. Culture of CMT positive quarters
ANIMAL No. 1 3 4 19 27 30 31 39 40 52 53 55 57 64 74 78 91 93
104
Strep species X x
Staph aureus
Coryne species
Staph species
No growth

66. Troubleshooting contagious mastitis
Liner squawks
Post-dip coverage
Dip NMC tested
Appropriate dry cow treatment
Identify individual Staph. aureus cows

67. Culture of CMT positive quarters
ANIMAL No. 71 55 50
315 72 12 79 47
316 77 57 82 36 83 62
172
QUARTER RR LF LR RF
Strep uberis X
Staph hyicus
Staph epi
Staph aureus
No growth

68. Troubleshooting environmentals
Check environment
Visit the dry cow lot
Kill time for pre-dip
Teats and base of udder dry?
Time attachment delay
Time how long it takes to milk cows
Examine teat ends
Time the detachers

70. Farm monitoring No. of clinicals Bulk tank SCC reports
3 cases/100 cows per month
Count mastitis tubes used
20 cases/100 cows per year
Bulk tank SCC reports
DHIA linear scores and hot sheet
Bulk tank cultures
Surveys show wide range from 2/100 cows to over 100/100 cows/year

72. Bulk Tank Cultures Good for Strep. agalactiae Mycoplasma surveillance
Not good for Staph. aureus
all herds affected
Variable shedding
Does not distinguish high/low herds
Environmental bacteria – origin?

74. Udder edema