bovine mastitis and production of quality milk (Donovan) Flashcards
alveoli
- milk synthesis
- oxytocin responsive smooth muscle
ducts and ductules
collection of milk
gland (udder) cistern
storage of letdown milk
teat cistern
storage of letdown milk just prior to removal (milking or suckling)
teat canal
- first and most important line of defense against invasion by patogenic bacteria
- smooth muscle
- squamous epithelium and thick layer of keratin
- keratin: bacteriostatic properties
mastitis (def)
- inflammation within the mammary gland
- complex disease
- many causes
- varying intensity
- variable duration
- variable residual effects
inflammation characterized by
- heat
- pain
- redness
- swelling
- disturbed function
clinical forms of mastitis
peracute
- most severe form
- CS progres over 4-12 hour period
- local signs severe plus systemic signs
- fever
- anorexia
- dehydration
- depression
- muscle tremors
- +/- diarrhea
- death
Clinical Forms of mastitis
acute
- all five gross signs of inflammation
- mild depression and fever
Clinical forms of mastitis
subacute
- cardinal signs of mastitis subdued
- no systemica signs
- most common clinical form
Clinical forms of mastitis
Subclinical
- inflammation in absence of gross signs (only detected in milk)
- Leukocytes, fibrin clots, serum in milk
- most common form of mastitis
Clinical form of mastitis
Chronic
- inflammation persists over weeks/months
or
- periodic flareups that produce acute or subacute clinical signs
Primary udder pathogens
- staph aureus
- strep agalactiae
- mycoplasma sp
- strep dysgalactia
Environmental pathogen (major)
- Strep uberis
- Strep dysgalactia
Environmental pathogens (minor)
- staph coag neg
- Colforms
- A. pyogenes
Streptococcus agalactiae
- non tissue invader
- pathogenesis
- irritant accumulates
- decreased milk production
- inc som cell count
- susceptible to penicillin and others
- can be eradicated
- rare on farms
somatic cell counts
- leukocytes
- epithelia cellular debris in milk
Control of strep ag in a herd
- post milking teat disinfection
- dry cow therapy
- ID infected cows and treat
Dry cow therapy
- at the end of 300/330 days
- infuse antibiotics into mammary gland
- routine on all dairy farms
Blitz treatment
- post-milking teat disinfection
- dry cow Ab therapy
- treatment of all strep ag positive 1/4s
only bug controlled by TX
strep ag
Staphylococcus aureus
- contagious mastitis
- mainly subclinical and chronic
- micro-abscessation within the gland
- peracute form less common
- this leads to gangrene of udder
- reservoirs
- milk
- teat skin
staph aureus
pathogenesis
- penetrates into tissue
- produces deep-seated foci of inflammation
- produces toxins
- coagulase
- hemolysis: gangrenous mastitis
- penicillinase
- beta lactamase
staph aureus shed in
relatively low numbers
staph aureus causes moderate
increase in somatic cell count
staph aureus controlled by
- teat dipping
- prevention
*can’t be controlled by treatment
Mycoplasma sp
- contagious mastitis organism
- of most concern is M. bovis
- also causes penumonia, otitis media/interna & arthritis in calves
- often subclinical
- mastitis can spread to all 4 quarters
- white coffe-ground appearance to milk
difficulty in treating/detecting mycoplasma sp
- non-responsive to AB
- periodic shedding possible
- specialized culture media required
strep uberis &
strep dysgalactia
- environomental
- non susceptible to eradication
- opportunistic
S. uberis
- acute and chronic mastitis
- indistinquishable from strep ag
S. dys
- infections after teat injury
- enhanced by presence of teat lesions
- viral
- mechanical
- chemical
- chapping
95% rule
- 95% of mastitis due to
- strep ag
- staph aureus
- strep uberis
- strep dysgalactia
- coliforms
Coliforms
- environmental, opportunistic organisms
- E. coli, Klebsiella, Serratia, Aeromonas
- cause peracute to acute mastitis
- can kill cows
- low numbers of bacteria shed in milk
Herds wtih low SCC may be at inc risk of
- acquiring coliform infections
- protective effect of elevated SCC
one of the first signs of peracute mastitis
watery milk
coliforms mastitis
- characteriazed by
- sudden sweeling of affected quater
- fever, muscle tremors, rumen statis, dehydration, +/- diarrhea
- udder secretion serous w/o leukocytes (pus) or fibrin, and later with both in milk
Coliform pathogenesis
- Endotoxins
Monitoring and assessment of herd mastitis
- # clinical cases
- Bulk tank milk eval
- California mastitis test
- Individual somatic cell count
Goal for mastitis
- < 3% of milking population/month
- 0.75%/week
consideration when counting # clinical cases
- stage of lactation
- geographic location
- parity (1st lactation cows…?)
contagious mastitis bugs
(purist perspective)
- staph aureaus
- strep ag
- mycoplasm
coliform contamination from
feces
(look at bedding)
regulatory limit of somatic cell count
450,000 cells/mL
California Mastitis test
- indirect measure of somatic cells in milk
- good screening test for subclinical mastitis in a herd
- good at IDing cows with high SCC (>1,000,000)
- Not good for differentiating between infected (>200,000) and non-infected cows (<200,000)
Mastitis Control Program
- proper milking management
- environmental control
- dry cow therapy
- milking machine maintenance
- treatment protocols
- vaccination
Pre-milking management
- quietly bring cows into milking parlor to be milked
- avoid excitement
- thoroughly clean and dry udder and teats
- dry is preferable to clean
- dip (contact time)
- iodine (30 seconds)
- chlorine (5-10 seconds)
- strip (look for mastitis)
milking management
- avoid liner slips
- vacuum leak
- contributes to severe coliform mastitis
Post-milking management
- make sure cow is milked out
- dip all 4 teats
- send cow on her way to a feedbunk full of fresh feed and water
- keep them standing!
Environmental control
- bed freestalls at least once daily
- control heat stress
- dry cow therapy
- infuse AB into mammary gland
vaccinations against mastitis
- E. Coli
- core vaccine, only one that works
- Staph aureus
- Mycoplasma bovis
Summary
- Milk clean, dry teats
- post-milk disinfection
- dry, clean housing
