Contagious Mastitis Flashcards
What is the importance of mastitis?
- Expensive to the owner
- Painful to the cows
- Alters flavor for consumer
- Potentially spreads disease
How many teats does a cow have? Goat?
Cows have 1 udder and 4 mammary glands (quarters)
Goats have i udder and 2 mammary glands (halves)
What is the basic pathogenesis of mastitis?
Organisms on teat enter the teat and make their way to the mammary gland –> colonize the milk gland and cause mastitis
How can you control mastitis?
Remove organisms from skin, limit organism multiplication or remove from interior quickly, treat/ manage cows with active infection
What defenses prevent bacteria from entering?
Teat canal has a physical barrier (teat sphincter, keratin plug) and some antimicrobial activity
What defenses prevent infection from occuring
Phagocytic WBCs/ somatic cells
A healthy gland has >100,000 cells/mL (mostly mononuclear)
An infect gland has 200,000 - 1,000,000 cells/ mL (mostly PMN)
What is the predominant form of mastitis?
Subclinical mastitis –> no visible signs but affects yield and competition
How do you read a California Mastitis Test?
N=Negative –> no infection, no mixture thickening
T=Trace –> possible infection, mixture thickening, trace reaction, 300,000 SCC (subclinical mastitis)
1 = Weak Positive –> Infected, distinct thickening, no gel formation, 900,000 SCC (subclinical mastitis)
2 = Distinct positive –> Infected, immediate mixture thickening, 2.7 million SCC (serious mastitis)
3=Distinct Positive –> Infected, gel forms and looks like a fried egg, 8.1 million SCC (serious mastitis)
What is the predominant form of clinical mastitis?
Mild clinical mastitis –> has visible changes in milk color/ viscosity/ consistency
What clinical signs do you see with moderate clinical mastitis?
Changes in milk and visibly inflamed gland (redness, heat, pain, swelling)
What is the least common form of clinical mastitis?
Severe clinical mastitis –> has changes in milk, visibly inflamed gland, and sick cow (fever anorexia, depression, dehydration, weakness, death)
How is contagious mastitis spread?
From cow to cow at milking time, milk-contaminate fomites
Reservoir = mammary gland
Will usually be persistent and subclinical
How is environmental mastitis occur?
Acquired when teat skin is infected with environmental pathogens
Infection acquired between milkings or dry period
Mastitis is transient and clinical
How long should you prep the cow to optimize milk ejection?
20-60 seconds
What are the most important fomites in the spread of mastitis?
Milking cluster, towels/ sponges used on more than 1 cow, hands on milking staff
Infection can also be spread when air slips into milking liner, causing pathogens to be spread from one teat to another
What is the best way to prevent new infections?
Post-milk teat disinfection
Needs to be applied appropriately
Also need to prevent spread through fomites, make sure equipment is working properly
Milk infected cows last/ separately
Cull
How do you diagnose contagious mastitis?
- Hi SCC in bulk milk
- High proportion of cows with high SCC
- Culture milk
What are the major pathogens of contagious mastitis?
Major mastitis pathogens: Strep agalactea, Staph aureus, Mycoplasma bovis (requires special conditions, not responsive to treatment –> get rid of cow)
Minor pathogens: Corynebacterium bovis
How do you treat contagious mastitis?
- Intramammary antibiotics during lactation/ during dry period (dry period has higher success rate)
- Cull
- Stop milking/ chemically inactivate gland
- Milk separately
How can you maximize the effectiveness of mastitis treatment?
- Select young animals with low infections/ SCC numbers
- Susceptible ABs –> test for B-lactamase
- Extended treatment length
- Vaccinate with commercial bacterin
What are some special considerations about staphylococcal contagious mastitis?
- Can potentially be transmitted by flies
- Control with pre-lactation antibiotics, fly control, nose rings
What are some special consideration about Mycoplasmal contagious mastitis?
- Can experience polyarthritis, respiratory disease, otitis media
Control by not feeding unpasteurized milk to calves and vaccinate
What is the purpose of the Minnesota Easy Culture System?
Easily to cultures certain bacteria, can be done by farmers, indicates whether the cow needs treatment or not
Why do you feed cows after milking?
- Make them stand long enough to form a fibrin plug –> prevents bacteria from entering
