The document provides information on proper dry-off procedures to prevent new intramammary infections and cure existing cases of mastitis. It discusses the physiology of the dry period and increased susceptibility to infection. Key recommendations include treating all quarters of all cows (blanket dry cow therapy) with antibiotics and sometimes also using internal teat sealants. Proper techniques for infusing antibiotics and sealants are important to avoid introducing bacteria. Management factors like nutrition, housing, and length of the dry period can also impact mastitis risk. Vaccination against environmental pathogens may provide additional protection against new infections.

1. Proper Dry-Off Procedures
to Prevent New Infections
and Cure Existing Cases
of Mastitis
Stephen C. Nickerson
University of Georgia
scn@uga.edu

2. Presentation Outline
• Intramammary infection process
• Anatomy & physiology of dry period
• Methods of drying off
• Antibiotic therapy
• Teat sealant treatment
• Role of Vaccination
• Other management factors

3. Result:
Decreased milk quality & yield
Adversely affects animal health
Mastitis Definition:
IMI
Mastitis (intramammary infection)
occurs when bacteria enter the
teat orifice, multiply within the
mammary gland, and elicit an
inflammatory response (↑SCC).

4. An understanding of:
Physiology of the dry period
Anatomy of teat end tissues
Instrumental in maximizing benefits of
properly drying off mammary quarters
to cure IMI and prevent new infections
Clinical/Subclinical
Mastitis

5. Physiology of the Dry Period
• Function of the mammary gland during
lactation: continuous synthesis/secretion
of large quantities of milk; then dried off.
• The mammary gland progresses through three
distinct stages:
– 1) Active involution
– 2) Steady state involution
– 3) Colostrum formation
• “Colostrogenesis”
After
dry-off
Dry Period:
Needed to optimize milk
production in next lactation
(↑ Susceptibility to mastitis)

6. 1 2 3
Active Steady
state
6-fold higher
(2-3 weeks)
(305 d)
(60 d)
Majority: Environmentals:
• Escherichia coli
• Streptococcus uberis
(In addition to
existing IMI)
>50% of all CM
in early lactation:
“Environmentals”
acquired during
the dry period
---Lactation---
Colostro-
genesis
Why the increased susceptibility at the beginning and end of the dry period?

7. 1. Active Involution
(Termination of milking→3-4 weeks into dry period)
• Maximum accumulation of fluid occurs
within ~2 to 3 days of drying off.
• Milk volume decreases significantly by
~4 days of involution.
• Fluid volume continues to decrease
through at least day 16 of the dry
period, and probably through day 30.
Milk
Result of: Resorption, some leakage

8. 1. Active Involution
(Increased antimicrobial activity)
• ↑Lacto-ferrin (LF):
– Binds to iron (Fe++) in mammary secretions
– Making it unavailable to bacteria that require
it for normal growth, like coliforms (E. coli)
– Plays a role in control of leukocyte activity
• Phagocytosis/killing
• ↑Antibodies
– IgG1, IgG2, IgA, IgM
• Enhance leukocyte function/neutralize bacteria
Neutrophil
Bacteria
LF
Fe
Fe
Fe Fe
FeFe
Fe Fe
Need Fe
for growth
Bacteria
But still, new infections occur…

9. Elevated rate of new infections
during active involution due to:
Flushing of colonized bacteria terminated
- No more 2-3 times a day milking
Udder sanit. & teat dipping discontinued
- Bacteria accumulate on the skin
Leukocytes more active in removing milk
components than microorganisms
Dilation and shortening of teat duct
- Milk pressure, leakage, ↓ keratin
Casein & fat: Inefficient

10. 2. Steady State Involution
(1-2 weeks)
• 1. High levels of antibacterial factors:
Antibodies & Lactoferrin (sequesters Fe)
• 2. Reduced rate of bacterial penetration
through the teat canal
– Lower level of teat end exposure
to potential mastitis pathogens
• The development of a keratin plug
(Functions as a physical & chemical
barrier: antimicrobial proteins & fats)
↓ Susceptibility to new infections due to:

11. • Susceptibility to new infection is
increased just prior to calving:
– Increased fluid volume → dilation of the
teat canal (leaking) allowing bacterial entry
– Reduced leukocyte numbers and loss of
their ability to engulf microorganisms.
– Utilization of milk components by mastitis
microorganisms → growth & multiplication.
– Absence of residual antimicrobial
activity of dry cow therapy.
• Lack of antibiotic residues from treatment
of all four quarters at the time of drying off
3. Colostrogenesis
(1-3 weeks prepartum)

12. Teat canal
Teat canal (duct) is the 1st line of defense, providing:
(A) Keratin and (B) Sphincter muscle
as physical/chemical barriers
Maintains tight
closure
• Physical plug
• Antibacterial
-Proteins
-Fatty acids
Keratin
Teat cistern
Role of mammary gland anatomy
in preventing new mastitis cases

13. When treatments are
applied to the teat end,
the natural tissue
architecture (keratin,
sphincter) should be
protected as much as
possible to maximize
treatment efficacy, e.g.,
Antibiotic or Teat seal
Protection of teat end tissues at
time of drying off: IMPORTANT

14. Full Insertion:
Stretches sphincter
Dilates teat canal
Removes keratin
Introduces bacteria
Partial Insertion:
Maintains integrity
Minimizes bacterial
entry into the gland
Environ.
bacteria
E. coli
Prototheca
Nocardia
T. pyogenes
Yeast
Partial
insertion
(2-3 mm)
Full
insertion
Bacteria

15. **Sanitize teat orifice, use partial insertion technique, dip teats
Using
gloves
Proper infusion procedures:
(Antibiotic or Teat sealant)
Kills contaminating bacteria

16. • Reduce feed over last 2 weeks to reduce yield
– Feed high fiber diet; eliminate grain; switch from
alfalfa to grass, or straw for very high producers.
– Reducing water intake is questionable as it is the
most crucial nutrient and promotes animal health.
• Dry-off at a BCS of ~3.5
• Abrupt cessation or intermittent milking
– Intermittent alleviates back pressure on milk-
producing cells; prolongs milk production.
• After dry-off switch to balanced gestation diet
• Provide adequate ventilation in housing
– ↓ moisture (reduces bacterial growth; ↓mastitis)
Management factors to consider at dry-off to
minimize stress and environmental exposure
*

17. Abrupt cessation vs. Intermittent milking
• Milk for ~291-298 days
– 1-2 weeks prior to dry-off date
• For last 1-2 weeks of lactation:
– Eliminate conc. (hay only)
– Limit water intake????
– Milk intermittently, e.g., 1X
• Infuse/place in far-off lot
Method of Drying Off
Accelerates involution
↓ New IMI at calving
(↓ production 22-47%)
• Milk for 305-day lactation
• Milking
• Infuse with DCT +/or TS
• Place in far-off pasture/lot

18. IMI rate based on method of dry-off and milk yield at dry-off
0
10
20
30
40
50
IMI Rate Reduced (%)
32
50
Intermittent milking*
Intermittent + Ration Change*
_________________
Oliver et al., 1990
*All quarters received DCT
*IMI defined as a change in LS from
<4.0 at dry-off to >4.0 at first test
___________________
Dingwell et al., 2001
“Leaking”
Reduction
in new IMI
vs. abrupt

19. Cows with greater milk yield at
dry-off → leak milk→ incomplete
keratin plug formation at teat end
Increases chances for bacterial
entry through the teat canal
Within several days-weeks,
teat canal closes up, with the
formation of a keratin plug
Decreases bacterial penetration:
Physical barrier, antimicrobials
Keratin plug

20. 50% of cows had open teat ends
(leaky) 1 week after dry-off
23% of cows had open teat ends
(leaky) 6 weeks after dry-off
47% of cows producing more than
46 lbs at dry-off had open teat ends
6 weeks after dry-off
______________
Dingwell, 2003
Research studies….
Greater risk of infection!
Leaky cows: 4X more likely to develop
clinical mastitis during the dry period
caused by envir. streps and coliforms

21. Mammary quarter infection status at dry-off:
1. 1.
2.
2.
Infected Infected
Uninfected
Uninfected
1. Existing intramammary infections that should be treated & eliminated
2. Uninfected quarters that should? be treated to prevent new infections
a) Antibiotic? b) Teat seal? c) Teat seal + antibiotic? d) No treatment?

22. Treat all 4 quarters
of all cows
Research into the use of
Blanket Dry Cow Therapy:
Treat & Prevent
Mastitis (No TS)
Treat all 4 quarters of all
cows at drying off
“Blanket DCT”
(1950s)

23. Qtr infection Rate Qtr Cure Rate New Qtr IMI
No. (%) No. (%) No. (%)
S. aureus 18 (2.78%) 17 (94.4%) 14 (2.16%)
S. agalactiae 23 (3.55%) 23 (100.0%) 11 (1.70%)
S. dysgalactiae 10 (1.54%) 10 (100.0%) 3 (0.46%)
S. uberis 0 0 1 (0.16%)
CNS 137 (21.14%) 107 (78.1%) 80 (12.34%)
E. faecalis 2 (0.31%) 2 (100.0%) 2 (0.31%)
E. coli 1 (0.15%) 1 (100.0%) 0
Other 2 (0.31%) 2 (100.0%) 2 (0.31%)
Total 193 (29.78%) 162 (83.9%) 113 (17.44%)
_______________
Petzer et al., 2009
Prevalence, cure rates, and new IMI of quarters treated at
drying off with various penicillin & cephalosporin products
Avg: 70-90% 40%↓ (Avg: 50-80%)
DCT: Cures IMI at drying off & prevents new IMI

24. Multiple antibiotic infusions? Improve cure rates?
• Treating twice at drying off, or
• At dry off & at some later time(s)
• Not demonstrated to be beneficial
• Subsequent treatments after dry-off may pose
additional risks:
– Introducing bacteria into the gland
via the syringe cannula
– Increasing risk of residues in bulk tank
milk after freshening
• Single infusion/qtr. recommended
– Antimicrobial activity persists 2-4 weeks

25. Selective Dry Cow Therapy (DCT)
External→ Internal→
X
• Selecting only the infected or potentially
infected quarters or cows to treat
• To reduce expense, drug use, & development of
antibiotic–resistant bacterial strains
• Selection based on culture, SCC (Electronic, CMT)
– Reasonable threshold: 200,000/ml (treat >this level)
• For cows/qtrs assumed uninfected (<200,000/ml):
– Teat sealants may prevent new infections:

26. Effects of Blanket vs. Selective DCT on
the prevention of new infections
• 729 low SCC cows (<200,000); 16 herds
– 1. Blanket: All 4 qtrs received DCT + Teat seal
– 2. Selective: Only infected cows received DCT + Teat
seal based on + bacterial culture results
• Culture-negative cows received teat seal only
Conclusion: Selectively treating culture+ cows = blanket therapy at dry off
*When SCC at dry-off are <200,000/ml
% Quarters
infected
at calving
_________________
Cameron et al., 2014

27. Effects of Systemic vs. Intramammary
therapy on Gram+ cure rate after DCT
• 278 cows in 1 herd assigned to 4 tmts:
– 1. DCT + Teat seal (Tomorrow®, Orbeseal®)
– 2. DCT + Teat seal + Tylosin (12 g, IM)
– 3. Teat seal + Tylosin
– 4. Tylosin
Contreras et al., 2012
% Cows cured
ab
ab
a
b
ab P < 0.05)

28. Use of Internal Teat Sealants at Dry-off
Physical barrier
to Bacteria
• Bismuth/paraffin based
• Infused at drying-off
• + after dry cow therapy
• Removed at 1st milking
Orbeseal™
Bismuth subnitrate/mineral oil
Teatseal®
Bismuth subnitrate/paraffin oil

29. Teat seals: Initial studies - United Kingdom
(Huxley et al., 2002)
• 505 cows with SCC at dry-off of <200,000/ml
• 2 treatment groups:
– 1. Orbeseal (65% bismuth subnitrate in mineral oil)
– 2. Cepravin (250 mg of cephalonium)
• Measured:
– New infections during dry period
– Clinical mastitis in 1st 100 DIM
• Objective: Orbeseal = DCT?

30. Teat seals: Initial studies - United Kingdom
(Huxley et al., 2002)
*
New infection rate with various mastitis pathogens
*Orbeseal use: 70% fewer E. coli IMI (P<0.01)
Orbeseal = DCT, but better in preventing coliform IMI
25 24
42
15
35
21
183
162

31. Efficacy of Orbeseal™ + DCT
in 437 cows (1748 qtrs)
1. All 4 qtrs infused with DCT
2. 2 contralateral qtrs: Orbeseal
RF
LF
LR
RR
Compared with DCT alone, DCT + Orbeseal →
• 30% fewer new infections during dry period
• 33% less likely to develop clinical mastitis
• Lower SCC in early lactation
• Combination superior to DCT alone
________________
Godden et al., 2003

32. Efficacy of Orbeseal™ + DCT
in 949 cows (multi-herd)
1. 2 qtrs infused with DCT alone
2. 2 contralateral qtrs: DCT + Orbeseal
RF
LF
LR
RR
Compared with DCT alone, quarters treated with DCT + Orbeseal:
• 27% less likely to acquire new IMI (all pathogens) during dry period
• 38% less likely to acquire new IMI (environmentals) during dry period
• 58% less likely to acquire new IMI (coliforms) during dry period
________________
Sanford et al., 2006
Combination superior to DCT alone, vs. *environmentals, **coliforms

33. Summary: Teat sealants + DCT
_____________________
Rabiee & Lean, 2013 (Meta-analysis of 12 trials)
↓new IMI at calving & Clinical mastitis
Addition of DCT lowers SCC (cures IMI)
+ or
Equally
effective

34. Proper teat seal infusion:
1. Compress area at base
of teat with hand.
2. Insert cannula using the
partial insertion method
3. Slowly infuse contents
so seal remains in teat
1.
2.
If teat cistern is open to gland
cistern, and seal is jetted into
teat, it may be placed high in
the quarter and milk out for
days or weeks after calving.
←Teat cistern
←Gland cistern

35. • Cooling during warm season (H2O/sprinklers)
– ↑ comfort, DMI, immune function (↓mastitis)
• Daily bedding maintenance/clean pasture
– ↓ pathogen load at teat end (↓mastitis)
• Provide proper nutrition & supplements
– Se, Cu, Zn; Vit. A, D, E; additives (Omnigen)
• Improve leukocyte function vs. mastitis pathogens
• Length of the non-lactating or dry period
– 1ST lactation cows: 50-60 d; Multiparous cows: 35-45 d
• By milking high-producing cows longer (45- vs. 60-day dry
period), yield will be lower when it is time to dry them off
• Vaccination against environmental mastitis…
Other management factors to consider

36. Vaccination during the dry period
to reduce incidence of coliforms
• Coliform vaccines at dry-off & after calving
– ↓ Clinical mastitis postpartum (2.6% vs. 12.8%)
– Returns $57/cow and profitable when >1% of herd
has clinical coliform mastitis
– 30-40% of all US cows are currently immunized
– Vaccination does not overcome poor environmental
conditions or housing over the dry period
(Gonzalez et al., 1989)
(DeGraves & Fetrow, 1991)
(Hoards Dairyman, 2013)

37. Coliform vaccination schedule
Endovac bovi
2X , 2-3 weeks
apart
Up to 80% effective in preventing
new cases of clinical coliform IMI
J-VAC
2X, 2-4 wk
later
Envirocore
3X, 7 & 8 mo,
<2 wk calving

38. Summary
• Proper dry-off methods DO promote udder health
• Decrease dietary energy last 1-2 weeks; increase fiber
• Abrupt cessation = Intermittent milking/diet change
– Intermittent: High producers (↓production, ↓leakage at DO)
• Dry period length- Heifers: 50-60 d; Multi: 35-45 d
– Milk high producers longer to decrease yield (↓volume)
• Selective = Blanket for low SCC cows <200,000/ml
– DCT + Teat seal recommended to maximize benefits
– Use Blanket DCT for high SCC cows/herds >200,000/ml
• Use recommended infusion techniques (keratin, sphincter)
• Coliform vaccines: ↑Immunity ↓CM in early lactation

39. ?Questions??The End
THANK YOU