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Food Animal Medicine > Bovine Mastitis > Flashcards

Bovine Mastitis Flashcards

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1
Q

What is a Standard Plate Count? What are 3 common sources that make the count higher?

A

A plate count is the measure of the number of bacteria within milk. Three common sources of bacteria in milk:
*Udder pathogens
*Teat hygiene
*Milking machine

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2
Q

What are the legal limit and target levels for plate counts in milk in the US?

A

100,000/ml (target level less than 5,000/ml)

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3
Q

What is SCC and what are the legal limit and target levels for SCC in milk in the US?

A

SCC=Somatic Cell Count (WBCs and epithelial cells in milk)
SCC Limit =750,000/ml
SCC target = 150,000/ml

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4
Q

What are the 2 types of SCC counts?

A

Bulk tank and individual cow

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5
Q

What is the SCC limit for determining individual cow infection?

A

200,000/ml

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6
Q

How are the terms “mastitis” and “intramammary infection” different?

A

Mastitis = Inflammation of mammary gland caused by reaction to tissue injury
LOSS OF FUNCTION

Majority of this inflammation is a result from INFECTION!!

Intramammary Infection = An infection of the mammary gland

> 90% are bacterial infections

Mastitis & Intramammary infections are often use interchangeably

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7
Q

What constitutes a mild case of mastitis?

A

*Abnormal milk (clots present or watery milk)
*Udder and cow are NORMAL

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8
Q

What constitutes a moderate case of mastitis?

A

*Abnormal milk
*Abnormal udder – hot, swollen, inflamed, painful quarter(s)
*Cow is not off-feed yet but may have an abnormal physical exam finding

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9
Q

What constitutes a severe case of mastitis?

A

*Abnormal milk (may be serous secretion)
*Abnormal udder (as seen with moderate cases)
*Cow is abnormal- showing systemic illness
*Physical exam findings / signs appreciated: off-feed, abnormal temperature, increased heart rate , increased respiratory rate, cold ears, decrease ruminations, unable to rise, dehydrated

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10
Q

What are the 4 goals of a mastitis control program?

A

1- Prevent new infections
2- Eliminate existing infections
3- Maximize milk quality
4- Keep SCC low

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11
Q

What is the main barrier to infection of the udder in a cow?

A

Teat end defenses- keratin plug

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12
Q

What are 6 good hygiene practices in milking?

A

1- teat pre-dip (correct contact time)
2- teat post-dip (correct contact time)
3- clean milking unit and flush between each cow
4- limit unit-on time
5- milk high SCC cows LAST
6- wear gloves

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13
Q

What are 2 milking practices related to total time spent with milking unit on that increase risk of mastitis?

A

Undermilking (>500 ml milk left) and overmilking (<250 ml milk left)

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14
Q

What is the best cow bedding material for maximal udder hygiene?

A

Sand

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15
Q

What is a chronic carrier and what is the best way to manage them?

A

Chronically infected with HIGH individual SCC from one lactation to the next. Abx treatment does not clear infection. Best to cull chronic carriers.

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16
Q

What is a CMT and how do you use it and what do the results tell you?

A

California mastitis test. Add equal milk from all 4 quarters and equal volume of reagent to paddle. Swirl, tip, and look for viscosity/gel formation which indicates high cellularity. It is a qualitative test for SCC used for screening individual cows at milking.

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17
Q

What are 3 diagnostic methods used to screen for mastitis in a herd?

A

CMT testing, Somatic cell count testing, Culture and sensitivity

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18
Q

What is the reason for a no growth result on milk culture in a cow with mastitis? In this case, how do you treat?

A

Inflammatory cells have current infection under control and there are no viable organisms remaining.
No antibiotics is the BEST option when nothing grows on culture or when nothing is known to be effective – i.e. Mycoplasma infections.
Anti-inflammatories and fluid therapy may be warranted if animal is showing signs of udder inflammation or systemic illness.

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19
Q

What is the process for sampling an individual cow for milk culture?

A

Collect PRIOR TO MILKING. Wear gloves, use pre-dip and clean teats, strip 3-4 streams first, scrub with alcohol and LET DRY, fill tube, label including quarter, and IMMEDIATELY refrigerate or put on ice.

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20
Q

What is the process for sampling the bulk tank for milk culture?

A

Agitate well > 10 min, take sample from TOP of tank, clean technique, serial samples daily for 3-5 days, freeze immediately (unless looking for prototheca)

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21
Q

What are the 3 major contagious pathogens and 2 major environmental pathogen groups that cause mastitis?

A

Contagious:
1- Staphylococcus aureus 2- Streptococcus agalactiae
3- Mycoplasma bovis
Environmental:
1- Coliforms
2- Environmental Streptococci

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22
Q

What is the 5-point plan for control of contagious mastitis pathogens?

A
  1. Dry cow therapy (intramammary Abx)
  2. Post milking teat dipping
  3. Regular milk machine maintenance
  4. Treat clinical mastitis cases
  5. Cull chronically infected cows (> 2 treatments in single lactation) and animals infected with M. bovis (not treatable)
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23
Q

What is the most common cause of clinical mastitis in dairy herds? Signs? How is it spread? Reservoir?

A

Staphylococcus aureus. Acute: Swollen, hot, painful udder
Chronic: Decreased production, abscess formation within the udder, HIGH SCC
+/- Systemically ill
Contagious – spread at milking. Chronic carriers.

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24
Q

What organism causes bluebag aka gangrenous mastitis in dairy cows?

A

S. aureus

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25
Q

What organism would you suspect in a case of A) severe, acute mastitis? B) Down cow with mastitis/toxic case? C) clinical mastitis that comes up as negative repeatedly on culture? D) mild cases of mastitis with high SCC?

A

A) Staph aureus
B) Coliforms (E. coli, Klebsiella)
C) Mycoplasma bovis
D) Strep agalactiae

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26
Q

What are typical signs of Strep. agalactiae mastitis? Mode of transmission? Reservoir?

A

Typically, mild cases with chronically high SCC and periodic clinical mastitis. Contagious – spread at milking. Obligate udder pathogen, found normally on udder exterior.

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27
Q

What are signs of infection with Mycoplasma bovis? How is it spread?

A

Clinical mastitis cases, high herd SCC, reproductive disease, in calves- pneumonia, otitis media, arthritis. Contagious pathogen – spread at milking

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28
Q

What diagnostic results would make you suspect infection with Mycoplasma bovis? What might milk look like from affected udders?

A

Clinical mastitis signs and repeated negative cultures on blood agar. Secretions = brown, sandy, serum to watery

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29
Q

How do you test for Mycoplasma bovis?

A

Specific mycoplasma culture and PCR

30
Q

How should you treat Mycoplasma bovis infection?

A

Treatment INEFFECTIVE & may cause carrier status
*Identify & cull from herd
*Eradication may occur with aggressive management & culling

31
Q

What are signs of mastitis due to coliforms? How are they spread and what is the reservoir? How are they treated?

A

Mostly mild mastitis cases, but some severe toxic cases with systemic illness/down cows due to endotoxin release. Environmental. In mild cases, no treatment is needed.

32
Q

How can coliform mastitis be prevented?

A

Environmental sanitation, sand bedding, feed cows after milking to keep standing until teat closure.

33
Q

What mastitis organism is found in wood shavings? Straw bedding?

A

Wood shavings =Klebsiella, Straw bedding = Streptococcus.

34
Q

What is the most common cause of subclinical mastitis in dairy herds?

A

Coagulase-negative Staphylococci

35
Q

What 4 drugs are prohibited from extra-label use in food animals?

A

CMEP
Cow Meds Extra label Prohibited
aka
Chloramphenicol
Metronidazole
Enrofloxacin
Phenylbutazone

36
Q

Where can you find withdrawal periods for drugs used in food animals?

A

FARAD

37
Q

What are the 3 levels of mastitis case severity and how are each treated?

A

MILD- milk abnormal, udder normal, cow normal. Treat: Monitor or IMM.
MODERATE- milk abnormal, udder abnormal, cow +/- abnormal but still eating. Treat: IMM, NSAIDS, monitor closely. SEVERE- milk abnormal, udder abnormal, cow abnormal and off-feed. Treat: IV hypertonic saline + oral fluids, IV or PO Ca, NSAIDS or steroids, IV Abx.

38
Q

What properties of Banamine (flunixin meglumine) make it useful in treating severe mastitis cases? By what route must it be given?

A

1- Anti-inflammatory
2- Analgesic
3- Anti-endotoxin
Must be given IV.

39
Q

Describe an example of a protocol for toxic mastitis.

A

*2 liters hypertonic saline IV plus 10-15 gallons of water with 100 grams of KCL orally
(Raises blood pressure & increases tissue perfusion)
*Flunixin meglumine IV; up to 3 days a treatment
*Systemic antibiotic therapy- eg Oxytetracycline-100
*IV and/or oral calcium supplement (gel or Bovikalc bolus)
*Strip out affected gland 3-4 times a day

40
Q

What should you do before giving IMM tube treatments?

A

Always clean the teat end off with alcohol (and let it dry!) before putting anything into the teat.

41
Q

When should you treat gram negative mastitis infections with antibiotics?

A

Only in severe cases involving bacteremia.

42
Q

What are 3 steps in dry cow management?

A

1- Abrupt dry-off
2- Dry cow IMM therapy
3- Sealant therapy

43
Q

What types of organisms do mastitis vaccines provide protection against? How effective are they?

A

Gram negative bacteria. Do not prevent infection but reduce disease severity.

44
Q

How often and when are mastitis vaccines administered?

A

3 times per year: dry-off, pre-fresh, post-fresh.

45
Q

What arteries supply blood to the cow udder?

A

Arterial supply – External Pudendal & Mammary arteries

46
Q

What veins drain blood from the cow udder?

A

Venous drainage – External Pudendal, SubQ abdominal, & Perineal veins

47
Q

What lymph nodes drain the cow udder?

A

Supramammary LN

48
Q

What causes high SCC?

A

Mammary infection

49
Q

What is the predominant cell type in high SCC milk samples?

A

Neutrophils

50
Q

What makes the CMT reagent viscous?

A

DNA from lysed cells

51
Q

What are the possible CMT scores?

A

Trace, 1, 2, or 3

52
Q

What is a linear score and how is it used?

A

-Linear scores are used to evaluate the udder health status of a cow or herd
-Linear Scores are linearly related to lost milk production and calculated from SCC
-Somatic cell counts increase with the severity of udder infection. However, the corresponding milk loss does not increase at the same rate. The use of linear scores simplifies the prediction of milk loss.
-Doubling SCC, the LS increases by one

53
Q

What type of pathogens usually cause chronic mastitis?

A

Contagious pathogens (as opposed to environmental)

54
Q

What are the components of milk?

A

Fat and protein

55
Q

How is milk removed from the teat in modern milking systems?

A

Suction via vacuum pump

56
Q

What is the problem with inflation slip in milking? How can you detect inflation slip in a milking parlor?

A

Inflation slips allow for reverse jetting of milk leading to penetration of udder pathogens into the quarter.
Listen for the “squawk”.

57
Q

What type of bacterial pathogens does the pre-dip prevent?

A

Environmental

58
Q

What type of bacterial pathogens does the post-dip prevent?

A

Contagious

59
Q

What are 3 possible components of teat dips?

A

Disinfectant, skin conditioner, barrier film

60
Q

What are clinical signs of a severely toxic cow?

A

Temperature : < 101°F or >103.5 °F
Heart rate : >90 beats per minute
Respiratory rate : >50 breaths per minute
*Skin tent over eyelid >3 seconds
*Appreciable dehydration >5%
*Decreased rate of rumen contractions < 3 contractions in 2 minutes

61
Q

What is the SCC cut-off for a healthy quarter? What CMT score does this correspond to?

A

200,000 cells/ml, negative

62
Q

What SCC does a CMT trace positive correspond to?

A

200,000 - 400,000 cells/ml

63
Q

At what CMT score does a quarter go from subclinical to serious mastitis? How many cells does this correspond to?

A

Between 1 and 2 (1 is subclinical and 2 is severe). 1.2 million (1,200,000) cells/ml.

64
Q

What diagnostics would you pursue only in mastitis cases where the producer would follow through with action based on the findings?

A

Ultrasound, biopsy

65
Q

What mechanism allows Staph aureus to evade antibiotic treatment and cause recurring mastitis?

A

Formation of abscesses

66
Q

Which types of mastitis pathogens can be effectively treated with antimicrobials?

A

Streptococcus agalactiae (contagious), environmental Streptococcus (dysgalactiae, uberis)

67
Q

What (less-common) mastitis-causing pathogenic bacterium likes to form biofilms in milk lines and in teat dips?

A

Pseudomonas aeruginosa

68
Q

What is an emerging mastitis-causing organism that is difficult to detect and treat?

A

Prototheca (alga)

69
Q

What mastitis-causing bacterium makes macroscopic abscesses in the udder? Microscopic?

A

Truperella pyogenes, Staphylococcus aureus

70
Q

How long do you have to keep medical records for mastitis?

A

3+ years depending on the state

Food Animal Medicine (6 decks)

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