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Mastitis in Dairy Cattle Flashcards

(57 cards)

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1
Q

What’s mastitis?

A

aka intrammamary infection (IMI)

caused by ascending bacterial infection

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2
Q

First line of defense against IMI?

A

teat canal
it’s closed by sphincter smooth muscle
open during milking, takes 30 minutes to close so keep it clean during this time

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3
Q

another physcial defense against IMI besides closed teat canal?

A

Keratin plug forms b/w milking
adsorbs bacteria
and antibacterial

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4
Q

Second line of defense against IMI?

A

Somatic cells:
Leukocytes
macrophages - normally found
neutrophils - found w/ infection

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5
Q

What SCC indicates infection?

A

> or equal to 200,000

if no signs: subclinical infection

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6
Q

Clinical IMI signs

A

abnormal milk (flakes, clots, watery)
+/- gland swelling
+/- abnormal cow

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7
Q

Sublinical IMI signs

A

None

SCC > or = 200,000

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8
Q

how to classify IMI severity?

A 
Grade 1 (mild) - abnormal milk
Grade 2 (mod) - abnormal milk & gland 
Grade 3 (sevre) - abnormal milk/gland/cow
90% are Grade 1 or 2
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9
Q

Gangrenous Mastitis
incidence?
pathophys?
etiology?

A

occurs sporadically
bacterial toxin causes vasoconstriction > ischemic necrosis
small ruminants: Staphylococcus aureus
cattle: E.coli

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10
Q

Common IMI pathogens?

A 
Gram neg/coliform/environmental
     E. coli
     Klebsiella
Gram positive
     Staphylococcus aureus
     Streptococcus agalactiae
     Environmental streps

Mycoplasma bovis (doesn’t stain)

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11
Q

How to treat IMI?

A

G positives: intramammary antibiotics

G negatives: neuts will take care of it

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12
Q

IMI disease severity?

A 
Gram positives
    cause chronic, subclinical infection
Gram negatives
     most not severe
     can cause severe IMI
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13
Q

IMI px?

A

Severity of gram negative disease reduced with “core-antigen” vaccine

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14
Q

IMI pathogen reservoirs?

A 
contagious (mammary gland)
spread during milking or cross suckling
     staph aureus
     strep. agalactiae
     M. bovis - most common contagious
environmental (housing/bedding)
      gram neg's - E.coli most common G-
      environmental streps
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15
Q

Milking parlor goals

A

efficiently milk clean, dry teats

prevent spread of milk from cow to cow

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16
Q

Milk parlor steps

A 
forestrip milk from each quarter
pre-milking teat dip
dry teats
attach milking unit
detach
post-milking teat dip
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17
Q

What’s forestripping?

A

take 2-3 strips of milk from each quarter to look for abnormalities (flakes, clots, watery)

stimulates milk letdown results in faster milking

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18
Q

pre-milking teat dip?

A

dip in 0.5% iodine (disinfectant)

controls environmental mastitis

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19
Q

drying teats step?

A

ONE TOWEL PER COW

to prevent spreading

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20
Q

post-milking teat dip?

A

dip in 1% iodine
to kill any transferred bacteria
and 10% glycerin (skin conditioner)
to prevent cracking

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21
Q

Key practices to control IMI?

A
  1. reduce milk spread during milking
  2. post-milking teat dip
  3. dry cow (not lactating) antibiotic Tx
  4. separate/cull infected animals
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22
Q

Steps to prevent environmental IMI?

A 
"core antigen" vaccine
CLEAN, DRY bedding
pre-milk teat dip
milk CLEAN, DRY teats
let cows stand 30 minutes after milking
      for teat canal to close
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23
Q

When does infection w/ environmental pathogens occur?

Study These Flashcards
A

occurs 4-5 times more during dry period
before and after calving
not milking so intramammary pressure
builds and opens teat end. Bacteria
more likely to enter into favorable
conditions

dirty straw bedding

during milking: dirty teats

24
Q

What’s the “core antigen” vaccine?

Study These Flashcards
A

used for IMI infections
mutant bacteria w/ exposed LPS core (endotoxin)
reduces severity of signs and clinical
cases

25
Udder health Diagnostics?
SCC | Aerobic milk culture and susceptibility testing
26
What do SCC's tell you?
udder health IMI status milk quality
27
How does the SCC test work?
Can be in lab test or cow side in lab: machine cow side: california mastitis test (CMT)
28
what is composite SCC?
When milk's collected from all glands and mixed into 1 sample for testing
29
Factors affecting SCC and interpretation?
older animals more likely to have IMI less specific in small ruminants test SCC during peak milk production SCC's appear higher during early and late lactation
30
How to interpret SCC's?
multiply reported value by 1,000/ml!
31
How does CMT work?
California mastitis test mix milk w/ detergent, cells lyse and release dna. DNA is viscous, so the more cells there are the more viscous the solution. cow side test, tests each quarter identifies subclinical IMI don't test abnormal milk b/c then there's no point, u can already tell!
32
What's BTSCC?
Bulk Tank SCC Milk from all cows into bulk tank then measure SCC gives you average SCC of herd positively related with IMI prevalence!!!
33
BTSCC legal limits?
US: 750,000 CA: 600,000 EU/Aus/NZ: 400,000 majority of our milk meets EU standards
34
relationship b/w herd size and avg SCC?
higher in smaller herds
35
When and why should you do milk cultures?
``` BT cultures to MONITOR for pathogens in herd Finding S. agalactiae not tolerated find infected cows and treat M. bovis not tolerated here coliform count tells us dirt teats were milked Individual clinical cow to IDENTIFY IMI cause individual subclinical cow w/ high SCC to IDENTIFY IMI cause ```
36
Tests to ID milk pathogens?
Aerobic Milk Culture Coagulase Test CAMP Test Special media for M. bovis
37
Aerobic milk culture test?
``` plate on Blood agar everything grows on this except M. bovis Then on MacConkey agar Selective media, only grows gram neg growth means: gram neg present and maybe gram pos too, it just doesn't grow on MacConkey ```
38
How to ID: M. bovis S. aureus S. agalactiae
``` M. bovis - request special media S. aureus - beta hemolysis on blood agar meaning, complete hemolysis Positive coagulase test to confirm S. agalactiae - Positive CAMP test S. ag forms the arrow! ```
39
Why do antibiotic susceptibility test?
to exclude antibiotics as possible treatments (when pathogen is resistant)
40
S. aureus characteristics?
gram positivie beta hemolysis coagulase positive
41
S. aureus infection characteristics?
Chronic, subclinical with intermittent clinical episodes | intermittently shed -> fals neg. cultures
42
S. aureus virulence factors
Aid in colonization * surface adhesins adheres to epidermis * resistant to keratin plug Evasion of immune system * Protein A prevents phagocytosis * Survival in neuts * Microabscess formation
43
S. aureus Tx?
``` Poor Tx efficacy * 50% resistant to beta lactam Abx * poor microabscess penetration * protected w/in neuts from Abx * L-forms have no cell wall so beta lactams not effective ``` bacteriologic cure (eliminating bacteria) less likely as infection duration increases.
44
S. aureus Px?
Vaccine unsuccessful | not recommended
45
S. agalactiae characteristics?
Gram positive | CAMP positive
46
S. agalactiae infection characteristics?
chronic, subclinical | high numbers shed in milk
47
S. agalactiae Tx?
Sensitive to beta lactam Ab
48
M. bovis characteristics?
No cell wall | special culture required!
49
M. bovis infection characteristics?
``` uncurable clinical mastitis disease in calves affects multiple systems mam gland, respiratory, urogenital spreads to multiple glands ``` signs in calves pneumonia, otitis, arthritis
50
M. bovis Tx?
No treatment cull positive cows if high prevalence, segregate into "Myco pen"
51
Environmental strep characteristics
Gram positive
52
Envir. strep. infection characteristics?
clinical mastitis | if not treated: chronic, subclinical
53
Envir. strep. Tx?
Abx Dry Tx (intramammary Abx infusion) if untreated -> chronic, subclinical infection
54
Coliform bacteria characteristics?
Gram negative | MacConkey positive
55
Colifrom bacteria infection characteristics?
short duration clinical mastitis resolves w/o Tx Sometimes severe dz
56
E. coli pathophys
rapidly multiplies in milk > e. coli death > endotoxin release > inflammation signs: udder firm and swollen, decreased milk production, fever, dec. rumen motility
57
Coliform Tx?
``` No Tx not susceptible to Abx Supportive care NSAIDs Fluids Systemic disease Tx ceftiofur may help ```

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