Term
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Definition
| inflammation of the mammary gland, typically associated with bacterial infection |
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Term
| What is the most economically important disease on a dairy farm? |
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Definition
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Term
| What is the number one reason for use of antibiotics in dairy cows? |
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Definition
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Term
| What factors play a role in whether mastitis will occur? |
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Definition
Agent: pathogens present in sufficient numbers
Host: immune function, teat health etc.
Environment: cleanliness, heat stress etc. |
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Term
| Why is the ability of the immune system compromised in defending the body against bacteria causing mastitis? |
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Definition
| the milk-blood barrier limits the ability of immune cells & antibodies to function |
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Term
| What is clinical mastitis? Describe the characteristics of each 'level' |
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Definition
visibly abnormal milk
Mild: flakes, clots, watery milk
Moderate: abnormal milk & swollen quarter
Severe: abnormal milk, quarter & systemic illness |
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Term
| How many days of production are lost for each clinical case of mastitis? |
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Definition
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Term
| What are some of the costs associated with clinical mastitis? |
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Definition
-labour
-waste milk
-treatment cost
-risk of drug residues
-risk of infection to other cows |
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Term
| What is subclinical mastitis? How is it detected? |
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Definition
inflammation but without visibly abnormal milk
detected by somatic cell count (neutrophiles present in milk) |
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Term
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Definition
somatic cell count
-measured weekly in bulk milk
-monthly on individual cows in herds on DHI |
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Term
| How does a California Mastitis test work? |
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Definition
| detergents react with DNA of neutrophils to form a gel |
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Term
| What are some general & pathogen specific means of controlling mastitis? |
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Definition
General
-milking hygiene & technique
-clean environment
-cow comfort
-dry cow therapy
Pathogen specific
-antibiotic treatment for clinical cases
-vaccination
-selective culling |
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Term
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Definition
-use of long-acting antibiotics to eliminate existing infection and prevent new infections during involution
-using a teat sealant to prevent introduction of new bacteria during the dry period |
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Term
| Describe the changes to the teat during the dry period |
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Definition
-within 2 weeks a keratin plug will form to seal the teat
-25% of teats will not seal, risk of infection!
-gland will be resistant to new infection, but existing infections may become clinical |
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Term
| What is the reservoir for transmission of contagious mastitis? What are the major agents |
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Definition
the cow's udder, transmitted cow to cow
streptococcus agalactiae
staphylococcus aureaus
mycoplasma bovis |
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Term
| Describe the characteristics of streptococcus agalactiae |
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Definition
-very contagious
-associated with subclinical mastitis, poor milking hygiene, lack of dry cow therapy
-very susceptible to IMM antibiotics e.g. penicillin |
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Term
| Describe the characteristics of streptococcus aureus |
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Definition
-establishes chronic infections, will show intermittent high SCC, clinical flare-ups, eventually become chronic high SCC with scarring of udder
-responds poorly to antibiotics as it is highly resistant |
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Term
| What is the reservoir for transmission of environmental mastitis? What are the major agents? |
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Definition
bedding, stalls, manure
coliforms e.g. E. coli
environmental streptococci e.g. uberis, dysgalactiae |
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Term
| What type of mastitis is typically caused by E.coli? |
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Definition
| environmental clinical mastitis |
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Term
True or False
Mastitis due to coliforms is the only type of mastitis that can be treated with a vaccine |
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Definition
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Term
True or False
Antibiotics are an excellent means of treating coliform mastitis |
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Definition
false, not responsive to antibiotics
Environmental streptococci can be treated with antibiotics |
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Term
| Describe the process of infection with coliform mastitis |
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Definition
-happens very rapidly, lasts 1-3 days
-bacteria invade the udder, grow rapidly
-short but severe infection
-endotoxin is absorbed by blood, hijacks the immune system creating an excessive inflammatory response
-immune system will eventually right off the infection |
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Term
| Do environmental steptococci typically cause clinical or subclinical mastitis? |
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Definition
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Term
| How long would an infection of environmental streptococci last? |
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Definition
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Term
| How can you control environmental mastitis? |
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Definition
-clean stalls
-sand bedding
-good ventilation
-clean floors & yards
-milking hygiene, pre-dip teat
-vaccination against coliforms
-nutrition to support immune function |
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