Mastitis

Question 1

What is considered subclinical mastitis? How does this compare to clinical mastitis?

Answer 1

infection and associated inflammation do not result in visible abnormalities in the milk, however milk production will be is reduced and and composition in altered

clinical = visibly abnormal affected quarter –> inflammation, dropped milk production, signs of systemic illness

Question 2

What somatic cell counts are indicative of subclinical mastitis?

Answer 2

200,000 cells/mL

(>100,000 cells/mL is indicative of inflammation)

Question 3

What are 2 options for diagnosing mastitis? How do they work?

Answer 3

1. California Mastitis Test (CMT) - 2-3 mL of milk from each quarter is stripped into a paddle with 4 compartments, CMT reagent is added to lyse cells and cause gelling fo the mixture –> graded from 0-3 (0 = <200,000 SCC)
2. electrical conductivity - increased sodium and chloride and decreased potassium in milk from mastitis cows result in an increased electrical conductivity

Question 4

What are the 3 degrees of clinical mastitis?

Answer 4

1. mild - abnormal viscosity, color, or consistency of milk
2. moderate - changes in milk + swollen, firm, red, and painful quarter
3. severe - changes in milk and quarters + systemic illness

Question 5

What 4 pathogens are responsible for contagious mastitis?

Answer 5

1. Streptococcus agalactiae*
2. Staphylococcus aureus*
3. Corynebacterium bovis
4. Mycoplasma - carried in sites other than the mammary gland, but become highly contagious once it makes it into the gland

(sweet, sweet cow milk)

Question 6

What are 5 options for controlling contagious mastitis?

Answer 6

1. routine use of post-milking teat dipping with a germicidal solution (iodine-based)
2. rubber gloves for milkers
3. backflush system on milking cluster
4. milk heifers before cows to prevent heifer infection
5. segregate S. aureus positive cows into a separate string to be milked last

Question 7

What are the major methods of treating cows with contagious masitis based on the pathogens they are infected with?

Answer 7

Streptococcus agalactiae and Corynebacterium bovis can be treated with intramammary antimicrobials

Staphylococcus aureus and Mycoplasma are more difficult to eradicate and the cows are typically culled

Question 8

What are some sources of environmental mastitis?

Answer 8

• bedding
• feeding material
• soil
• contaminated water

Question 9

What are the 3 major pathogens responsible for environmental mastitis? What are some other less common ones?

Answer 9

1. coliforms: E. coli, Enterobacter aerogenes, Klebsiella pneumoniae
2. Streptococcus uberis
3. Streptococcus dysgalactia

Arcanobacterium pyogenes, Prototheca, yeasts, Pseudomonas, Serratia, Nocardia, Mycobacterium, Pasteurella

Question 10

What pathogens can cause both contagious and environmental mastitis?

Answer 10

Staphylococcus hyicus and Staphylococcus epidermidis

• most prevalent bacteria isolated from milk of cows and heifers

Question 11

How in environmental mastitis controlled?

Answer 11

• frequent manure removal
• using appropriate free stalls and managing bedding
• providing pastured cows with clean locations to lie down –> sand preferred over wood, which predisposes to Klebsiella
• pre-dipping teats and having clean, dry udders at milking

dry cows MUST be included, commonly treated with intramammary antimicrobials and teat sealant