sandra godden dvm, dvsc college of veterinary medicine ... · dry period length 30 days 30 days 42...

Dry Cow Mastitis PreventionSandra Godden DVM, DVSc

College of Veterinary Medicine, University of [email protected]

Outline• Dry cow mastitis – define the problem

• Risk factors for dry cow mastitis

• Specific strategies to prevent new infections during the dry period

Dry Cow Mastitis: Why the Concern?

• Despite decades of research and steady progress, mastitis remains the most costly infectious disease affecting herds.

• Estimated loss of $200/cow/year for average upper Midwest dairy.

• Source of Losses:– 12% : Direct losses from clinical mastitis– 17% : Lost milk due to elevated SCC– 35% : Excess culling and death– 36% : Price reduction with elevated SCC

(Fetrow et al., 2000)

• Mastitis control strategies have successfully reduced the prevalence of contagious pathogens.

• Environmental pathogens have increased in relative importance.Environmental Streptococci(e.g. Streptococcus uberis)

Coliforms(e.g. Escherichia coli)

Natural Host Defences During the Dry Period

• The involuted dry gland is very resistant to new intramammary infections (IMI) due to:– Lactoferrin

• Increased concentration• Inhibits bacterial growth by binding iron

– Increased leukocyte activity• Increased concentration• Increased function (less interference from milk fat and casein)

– Keratin plug formation• Physical barrier• Fatty acids inhibit bacterial growth

Two Periods of High Risk for New Infections During the Dry Period

• Involution– No flushing action– Delayed keratin plug formation– Lactoferrin diluted– Inhibited leukocyte function

• Colostrogenesis (transition)– Protective factors diluted– Immune suppression– Keratin plug may break down– Antibiotic dry cow therapy (DCT)

levels below the minimum inhibitory concentration (MIC)

Incidence of new intramammaryinfections during the dry period

(Smith et al., 1985)

The Significance of Dry Period Infections• 50 - 60% of all new infections caused by environmental

pathogens occur during the dry period. (Bradley and Green, 2000)

• Over 50% of clinical coliform mastitis events in the first 100 days in milk originated during the dry period.

(Bradley and Green, 2002)

Origin of Infection (dry period or lactation) in cases of clinical mastitis (Green et al., 2002)

The Significance of Dry Period Infections

How Common Are New Infections During the Dry Period?

• Proportion of quarters developing a new infection during the dry period:– 8-12 % of quarters (Eberhart, 1986)– 17% of quarters (Dingwell et al., 2001)– 25% of quarters (Godden et al., 2003)– 6-26% of quarters (Cook et al., 2004)

• Large variation among herds

• An opportunity area for a majority of dairy herds.

Risk factors for New Infections During

the Dry Period• Herd:– Bulk tank somatic cell count (SCC)– Prevalence of infection– Herd management practices

(sanitation, heat abatement, crowding, other stressors, bedding management)

• Cow:– Lactation number: older cows at risk– High milk yield at dry off– Method of drying cows off

• Quarter:– Teat end exposure to bacteria– Teat end condition– Timely formation of keratin plug

Teat End Condition

• Hyperkeratosis predisposes teats to bacterial colonization.

(Fox, 1997; Timms, 1998)

• Cracked teats are at 1.8 times higher risk for acquiring new infections during dry period.

(Dingwell et al., 2004)

Hyperkeratosis – no crack

Hyperkeratosis – cracked

Keratin plug formation in streak canal important to prevent infection (Dingwell et al., Prev. Vet. Med, 2004)

Timely Formation of a Keratin Plug in the Teat Streak Canal Affects Susceptibility

Proportion of Quarters Failing to Produce an Adequate Keratin Plug During the Dry Period

• Williamson, 1995 10 days: 50% open

50 days: 10% open

• Dingwell, 20037 days: 50% open42 days: 23% open

– Delays if high milk yield

– Increased risk of infection if incomplete closure

Two main principles to prevent new infections during the dry and transition periods

• Maximize and supplement the cow’s defences

• Minimize bacterial challenge from the environment

Specific strategies to prevent new intramammary infections…



• Strategies to prevent new IMI during the dry period:– Blanket DCT– Internal or External Teat Sealants– Vaccination programs / Immunity – Dry-off strategies– Attention to housing, hygiene, and cow comfort



• Strategies to prevent new IMI during the dry period:– Blanket DCT – Internal or External Teat Sealants– Vaccination programs / Immunity – Dry-off strategies– Attention to housing, hygiene, and cow comfort

Blanket Dry Cow Therapy• Infuse all cows with long-acting

antibiotic at dry-off

• All labelled DCT products proven efficacious against negative control

• Very successful– Eliminates existing IMI caused by susceptible bacteria– Prevents new IMI during the early dry period– Has helped to reduce contagious pathogens

• Adopted by ≈ 80% of producers

(Smith, 1966; Browning, 1990; Bradley & Green, 2001; Bradley & Green, 2004; NAHMS 2007 )

Example Study: Efficacy of Dry Cow Therapy

• Approval study data for Spectramast DC (Zoetis)• Example: U.S. study of 21 herds • Cows with SCC > 400,000 cells/ml or LS > 5.0 enrolled at dry off• Cultured at dry off and at 3-5 DIM

Negative 500 mg ceftiofur Control hydrochloride

---------------------------------------------------------------------------------------# cows enrolled 84 86

% quarters cured 46.4% 61.8% *

% quarters w new IMI 46.7% 32.9% *

% uninfected at calving 43.7% 59.6% * --------------------------------------------------------------------------------* P < 0.05

(Hallberg et al., Vet. Therapeutics. 2006. 7:35-42 )

Equal Efficacy Among These DCT Products(Arruda et al., JDSci. 2013; Johnson et al. JDSci. 2015)

Spectramast® DC500mg

Ceftiofur Hydrochloride

Quartermaster®

1 x 106 units Procaine Penicillin G + 1g

Dihydrostreptomycin

ToMORROW®

300mgCephapirin Benzathine

Approx. cost $8.92/cow $ 9.56/ cow $ 11.33/ cow $ 18.66/ cow

Dry period length 30 days 30 days 42 days 30 days

Meat withhold 30 d after dry-off 42 d after dry- off 60 d after dry-off /96 h after calving 16 d after dry- off

Milk withhold 0 h after calving 72 h after calving 96 h after calving 0 h after calving

Claimed spectrum of action

S. aureus, S. agalactiae

S. aureus, S. agalactiae S. aureus

S. aureus, S. dysgalactiae,

S. uberis

Dry-Clox®

500mgCloxacillin Benzathine

Selective Dry Cow Therapy• Only cows or quarters with a

high probability of infection present are infused with antibiotic at dry off

• Not widely adopted yet (Denmark, Netherlands, Germany)

• A successful SDCT program requires:– Use of accurate diagnostic tests to identify infected quarters/cows– Use of internal teat sealant to protect untreated quarters– Can be considered in high health herds (BT SCC < 250,000)

(Cameron et al. JDSci 2014; Patel et al. MDHC 2016)

Dry Cow Teat Sealants• Internal teat sealants

OrbeSeal™or TeatSeal™ (Pfizer Animal Health)

• External teat sealantse.g. T-Hexx® Dry(Hyrdromer, Inc.)

External Teat Sealants

• Rapid drying plastic polymer

• Forms a physical barrier to entry by bacteria

Off the market:Stronghold®/DryFlex™ (WestAgro, DeLaval)

T-Hexx® Dry. (Hydromer, Inc.)

Reduction in new infections from Environmental Streptococci and CNS at calving

Timms, 2001

28.0%

22.7%

-18.9%25.2%

13.4%

-46.8%26.2%

-36.3%

16.7%

ControlDryFlex

Heifersn = 66

264 quarters

Cowsn = 124

492 quarters

(Dry cow antibiotic used on all quarters of all 190 cows in study.)

Total n = 190

756 quarters

Advantages and Disadvantages of External Sealants

(Persistent Barrier Dips)

Advantages:– Easy to apply– Rapid drying– Non-irritating / non-toxic

Disadvantage:– Shed off teat in 3-7 days– For full benefit must apply at dry off, and then reapply

at 10 days pre-calving, then repeat as needed until calving.

Stronghold® - Day 4

Internal Sealants

• OrbeSeal™ (North and South America)or TeatSeal™ (New Zealand and UK)

(Zoetis)

• Bismuth subnitrate in a paraffin base: 65% w/w (2.6 g in 4g)

• Infused into quarter after last milking at dry-off

• Insoluble in milk – excellent persistence

At Calving• OrbeSeal™ is easily

hand-stripped out of the quarter after calving.

• Safely ingested by calf. • No antimicrobial

properties or residue issues.

Studies Using TeatSeal™ in Uninfected Cows

(UK experience)

• U.K. studies of TeatSeal used alone in uninfected cows: – Somatic cell count < 200,000 cells/ml in previous lactation– No history of clinical mastitis in the previous lactation

• TeatSeal vs Nothing: – TeatSeal™ prevented more new infections during the dry period than no

treatment.(Berry and Hillerton, JDSci 2002)

• TeatSeal vs DCT: – TeatSeal™ prevented more new infections during the dry period than a long

acting intramammary antibiotic therapy.(Huxley et al., 2001)

Minnesota OrbeSeal™ StudyAssuming the North American dairy industry will

continue with blanket dry cow antibiotic therapy…

Describe the effectiveness of OrbeSeal™ in the prevention of new infections during the dry and transition period when used with an intramammary antibiotic

Minnesota OrbeSeal Study(Godden et al., JDSci 2003)

• 2 commercial free stall dairy herds

• 437 cows (1748 quarters)

• Random split udder design:– Antibiotic (control)– Antibiotic + OrbeSeal™

(treatment)

RFLF

LH RH

= Antibiotic

= OrbeSeal/Antibiotic

Minnesota OrbeSeal Study:Treatment and Sampling Schedule

Dry PeriodDry off Calving &

strip Orbeseal

CultureSCC+ Treatment

CultureSCC

CultureSCC

1-3 6-8 DIM

60 DIM

Record all clinical mastitis events from dry off to 60 DIM

Parameter Antibiotic Antibiotic + OrbeSeal™

Reduction in Risk (%)

New infection rate during dry period (%) 25.4% a 20.2% b - 30% Clinical mastitis rate during first 60 days in milk (%) 8.0% a 5.9% b - 33%

Linear Score at 6-8 days in milk 3.2 a 2.9 b

Minnesota OrbeSeal Study Results

a, b: P value < 0.05

Survival Curve for Clinical Mastitis Events in Quarters Between Dry Off and 60 Days In Milk

OrbeSeal

Control

MN study results later replicated by a 3-herd study in WI (Cook, NMC. 2004)

Summary on use of teat sealants• In known uninfected cows:

– Teat sealant results in fewer new IMI infections vs no treatment

• In cows of unknown infection status or infected cows:– Teat sealant + DCT combination reduces infections:

• 30 – 68% decrease in new IMI risk during dry period• 20 – 30% decrease in clinical mastitis risk in early lactation• Decreased somatic cell count after calving

– Must use clean infusion techniques

• Teat sealants will be a necessary component of a successful SDCT program!

Maximizing the Cow’s Immune Defences• Nutritional management during dry and transition periods:

– Dietary protein and energy– Vitamins: A,D and E – Minerals: Selenium, Copper, Zinc, etc..– Don’t restrict feed and water intake: palatable and available

• Prevent metabolic diseases: milk fever, ketosis

• Minimize stressors:– Good cow comfort– Excellent ventilation– Prevent overcrowding– Provide heat abatement

(shade, fans, sprinklers)

Maximizing the Cow’s Immune Defences Through Vaccination

• Vaccination with Gram-negative core antigens• Binds to LPS toxin

• Example: 2 commercial dairies in California, U.S.A– Vaccinated group: Vaccinate twice during dry period, once after calving– Unvaccinated control group

Vaccinated Unvaccinated P Value Group Group

-----------------------------------------------------------------------------------------------cows enrolled 233 227

n(%) Coliform mastitis cases 6 (2.6 %) 29 (12.8 %) < 0.005------------------------------------------------------------------------------------------------

(Gonzalez et al., Can.J.Vet.Res. 1989. 53:301)

Maximizing the Cow’s Immune Defences Through Vaccination

• Successful vaccination with gram negative core antigens during the dry period allows the immune system to more rapidly and effectively respond to natural infections:– Does not prevent coliform infections– Reduces duration and severity of coliform mastitis– Reduces death loss

(Cullor, 1991; Hogan, 1992, 1999)

• Routine vaccination beneficial and cost-effective in almost all herds

(DeGraves and Fetrow, 1991)

• Will not overcome poor management

How do we dry cows off?

• Limited studies available• Generally ignored in most extension publications

Dry-off

(from Dingwell, 2004)

Is there a best method for drying cows off?• High milk yield at dry-off is associated with delayed teat closure, leaking and higher risk for new

IMI in dry period (Oliver et al. 1956; Huxley et al., 2002; Gott et al., 2014)

• Strategies to reduce milk yield at dry-off should reduce mastitis risk:– Intermittent (vs abrupt) cessation of milking (SID) for last 2 wks

(Oliver, J. et al., 1956; Gott et al. NMC 2014)– Decrease energy ration density and limit water intake

(Oliver, S. et al., 1990)– Cabergoline - 5 mL IM (inhibits prolactin secretion)

(Bach et al. JDSci. 2015)

• However…– Limited research to demonstrate effect of these interventions in today’s high producing

cows (Gott et al., NMC. 2014)– Each herd should decide on a strategy to reduce milk production and

cease milking (Dingwell, 2004)

Abrupt vs Gradual Cessation of Milking – Effect on Risk for Dry Period Infections

(Gott et al., JDSci. 2016)

• Results:– Gradual cessation decreased milk yield by 33%– Primiparous cows: Gradual cessation reduced odds for quarters

being infected after calving (OR = 0.29)– Multiparous cows: Gradual cessation increased odds for quarters

being infected after calving (OR = 2.78)

Minimize Pathogen Exposure to the Teat End

• Requirements for bacteria to survive:– Moisture– Organic material: manure, soil, organic bedding

• Keep it clean and dry– Bedding selection – Bedding and manure management– Ventilation

Varying Potential of Different Bedding Materials to Support Environmental Bacteria Growth

(Godden et al., J.D.Sci. 2008. 91:151-159)

0

1

2

3

4

0 24 48 72Incubation period (hrs)

K. p

neum

onia

e grow

th (l

og 10(c

fu/m

l))

digested solidsnew sandrecycled sandshavings

a

d

b

c

a

bb

c

a

b

cc

a,b,c: different subscripts differ across bedding types at each time point (P<0.05)

Log phase growth

Stationary phase growth

Summary• The dry period is a high risk period for new IMI

• Principles to prevent new IMI during the dry period:– Maximize and supplement the cow’s defences– Minimize bacterial challenge from the environment

• Strategies to prevent new infections will include:– Blanket DCT– Internal or External Teat Sealants– Vaccination programs / Immunity – Dry-off strategies– Attention to housing, hygiene, and cow comfort

Thank you!

sandra godden dvm, dvsc college of veterinary medicine ... · dry period length 30 days 30 days 42...

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