93 terms


Which type of mastitis has visible signs of disease?
Clinical mastitis
Which type of mastitis has no signs of disease?
Subclinical mastitis
What is used to assess repeated bouts of mastitis?
Somatic Cell Count
What somatic cell count determines the difference between Grade A and Grade B milk?
750,000 cells
What are the two classifications of mastitis?
Contagious & Environmental
How is contagious mastitis spread?
from cow to cow
What type of bacteria are responsible for contagious mastitis?
Gram +ve
What specific bacteria are the main culprits for contagious mastitis?
Staph aureus
Strep agalactiae
Strep dysgalactiae
Mycoplasma spp.
Where does contagious mastitis live?
in the udders of infected cows
What type of illness is a contagious mastitis?
Clinical/subclinical/or chronic
(rarely toxic)
What is the bulk tank somatic cell count for contagious mastitis?
>300,000 cells
How is environmental mastitis acquired?
poor hygiene
...muddy, dirty environment
What type of bacteria are found in environmental mastitis?
Gram -
What specific bacteria are the cause of environmental mastitis?
E. coli
Streptococcus uberis (gram +)
What do we associate Streptococcus uberis with?
dirty straw bedding
What type of illness is environmental mastitis?
Acute (toxic)
Clinical (S. uberis)
systemically ill
Endotoxic shock
high mortality rate.
What are the classifications of mastitis by pathology?
Toxic mastitis
Clinical mastitis
Subclinical mastitis
Chronic mastitis
Gangrenous mastitis
Which path. classification is characterized by systemic disease (fever, anorexia, depression)?
Toxic mastitis
What type of bacteria and specific species are responsible for toxic mastitis?
Gram -
E. coli
Which pathological type has no systemic disease but has flakes and clots in milk and accompanying swelling?
Clinical mastitis
What type of bacteria and specific species are responsible for clinical mastitis?
Gram +
Which pathological types has grossly normal milk but has a high SCC on a CMT?
Subclinical mastitis
What type of bacteria and specific species are responsible for subclinical mastitis?
Staph aureus
Strep agalactiae
What pathological type has an elevated SCC, periodic flakes in milk and uneven quarters?
Chronic mastitis
What type of bacteria and specific species are responsible for chronic mastitis?
Staph aureus
Strep agalactiae
What pathological type is characterized by cold quarters, watery secretions and udder sloughing?
Gangrenous mastitis
What type of bacteria and specific species are responsible for gangrenous mastitis?
Staph aureus
Bacillus cereus
E. coli
Name the 6 major league bacteria in mastitis cases.
Staph aureus
Strep agalactiae
Strep dysgalactiae
Strep uberis
E. coli
What are the 7 minor league bacteria in mastitis?
Candida (fungus)
When you have a mastitis test come back with no growth, do you suspect major league or minor league players?
minor league
What are the 2 major pathogens with contagious mastitis?
Staph aureus
Strep agalactiae
Where does Staph aureus live?
in micro abscesses in the udder. this is why it is hard to beat
What type of infections is Staph aureus responsible for?
Subclinical, clinical, acute gangrenous, some chronic
Will you ever beat staph aureus?
no. sell the cow.
What type of pathogen is Streptococcus agalactiae?
Obligate Intramammary pathogen
Where does Strep agalactiae live?
in cisterns and ducts
How is Streptococcus agalactiae transmitted?
during milking
What type of infections does Streptococcus agalactiae cause?
rarely causes illness
will have a high herd SCC
Is eradication of Strep agalactiae possible?
yes, absolutely.
What type of therapy would you do for the herd?
Blitz therapy: treat all cows, wait for the withdrawal time and put them back into service.
What minor league pathogen will not be seen very often but, when it is, it will be a trainwreck?
What causes the difficulty of treating Mycoplasma?
It lacks a cell wall.
What anti-microbials will not work on Mycoplasma because of the lack of cell wall?
Beta lactams (penicillins)
What other anti-microbials are used to treat Mycoplasma? Are they successful?
Which cows are the important ones with Mycoplasma and how is this spread?
Chronic carriers are the important ones.
Producers feed mastitic milk to baby calves and they get pneumonia and arthritis. When the cow starts milking in a couple years the mastitis resurfaces.
Is Mycoplasma mastitis treatable?
No. Impossible to treat.
How can a dairy farmer avoid this?
don't feed mastitic milk or pasteurize the milk.
How is E coli spread?
Poor hygiene; FECAL MATERIAL
What causes the illness with E coli?
lipopolysaccharide release
What type of disease will E coli mastitis cause?
Severe systemic disease/ shock and death
How do you treat mastitis caused by E coli?
fluids, antimicrobials, NSAIDS, supportive therapy. (FANS)
How is Streptococcus uberis usually acquired?
It is associated with straw bedding during a dry period.
What does Strep uberis do to the milk?
causes clots
Why is Strep uberis difficult to treat?
it is an intracellular bacteria. It gets opsonized which limits phagocytosis.
Which of the following statements about Staphylococcus aureus mastitis is FALSE?
a. SA can cause gangrenous mastitis
b. SA is the most common cause of subclinical mastitis
c. SA mastitis responds well to antimicrobials
d. SA lives in micro abscesses
e. SA lives in white blood cells
c. SA mastitis responds well to antimicrobials
Which organism causes mastitis that responds well to intramammary treatment?
a. S. aureus
b. Mycoplasma
c. S. agalactiae
d. E coli
e. Prototheca
c. S. agalactiae
You are presented with a cow with S. uberis mastitis. The most likely source of the infection is....
straw bedding
Which of the following is NOT an environmental mastitis pathogen?
a. E coli
b. Arcanobacterium pyogenes
c. Mycoplasma spp.
d. Pseudomonas
e. Klebsiella
c. Mycoplasma
Which of the following organisms is commonly associated with endotoxin production following mastitis?
a. Mycoplasma spp.
b. Arcanobacterium
c. Klebsiella
d. Staph aureus
e. Prototheca spp
c. Klebsiella
You isolate Mycoplasma from a cow with mastitis. The most likely source of the infection is:
a. sawdust bedding
b homemade udder infustions
c. contaminated water
d. distillers grains
e. infected cows and calves
e. infected cows and calves
How long does it take for the teat sphincter to close after milking?
20-30 minutes
Which of the following is NOT a cytotoxin produced by Staph aureus?
a. lipopolysaccharide
b. leukocidin
c. Protein A
d. Staphylokinase
e. Alpha-toxin
a. Lipopolysaccharide
Damage to the teat ending is commonly associated with....?
exposure to cold
wet teats
skin infections
inadequate milk letdown
Bacterial colonization of the teat ending can be minimized by:
pre-milking disinfection
using one towel per cow to dry teats
Using post-milking disinfection
How can milk producers minimize the risk of bacteria entering the open teat canal?
prevent liner slips
maintain milking machine
regular liner change
keep cows standing after milking.
What are the goals related to preventing mastitis?
Minimize damage to teat/teat ending due to milking
Minimize bacterial colonization of teat ending during milking
Reduce risk of bacteria entering open canal.
Which of the following is the cheapest and most reliable way of diagnosing sub-clinical mastitis?
Udder palpation
Visualization of milk for flakes and clots
Gel formation on CMT
Culture on MacConkey's Agar
Changes in electrical conductivity
Gel formation on CMT
Which of the following is NOT a critical control point to prevent environmental mastitis?
Dry Cow management
Transitional cow management
Clean udders at milking
Clean dry comfortable cows
Prevent teat ending/ skin lesions and bacterial colonization
Prevent teat ending/ skin lesions and bacterial colonization
What are the possibilities if there is no growth on a culture?
Intermittent excretor (S. aureus)
residual anti-microbials
Incorrect sample handling
Unusual organism
Which of the following drugs is NOT banned for extra-label use in lactating dairy cows
What are the goals for dry cow therapy?
Treat existing infections
Prevent new infections
What is the goal of treating toxic mastitis?
Save the life of the cow
What does therapy consist of for toxic mastitis?
supportive therapy
Which of the following drugs will be most effective against coliform bacteria?
Which of the following drugs has a validated breakpoint for S. aureus mastitis?
What is Pseudomonas aeruginosa acquired from?
Contaminated water (water from wells used to spray udders)
also associated with "homemade" antibiotics
What does Arcanobacterium pyogenes cause? What is the mode of transmission?
Summer mastitis
transmitted by insects
What cows are usually affected by Arcanobacterium?
non-lactating cows and heifers.
What does arcanobacterium do to the udder?
causes it to be hard and swollen with a purulent foul-smelling discharge. Turns the udder into an abscess. Can be fatal
Where is Bacillus cereus acquired from? What pathological type of mastitis does it cause?
infected distillers grains
Gangrenous mastitis (coal black)
Where is Bacillus licheniformis acquired from?
cows lie in waste silage (especially corn)
Where is Serratia acquired from and what is it associated with?
Soil and water contaminants
potential IMM treatment/teat dip contaminant
Red milk
Where is Prototheca zopfii acquired from?
water contaminant
This is rare but if it happens it is disastrous
What causes Mycotic mastitis? Where is it acquired from?
Candida & cryptococcus
contaminated udder wash/ teat cups and homemade veterinary udder infusions.
What is the unclassified pathogen?
Coagulase-negative Staphylococcus.
Where are coag-negative pathogens found?
They are skin flora opportunists. They are the most frequently isolated bacteria from bovine milk samples.
What do you need to know about Streptococcus dysgalactiae?
it is half way between environmental and contagious.
lives in tonsils
carried by flies
What are the 4 ways to detect mastitis?
Visualization and palpation
Visualization of milk
Somatic Cell Count Detection (herd: Bulk tank SCC; individual: CMT)
Electrical Conductivity
When interpreting cultures, if you see no growth on the plates what are the possible reasons?
Intermittent excretors (bacteria living in micro abscesses)
residual anti-microbials are present
Incorrect sample handling
Unusual organisms (don't underestimate these)
How do you tell the MIC of a drug on a culture plate?
You must measure the zone of inhibition.
What is a breakpoint?
a specific MIC of a drug selected to predict the clinical outcome for a specific pathogen, specific disease, in a specific species, using a specific regimen.
How does mastitis culture results relate to clinical outcome?
No association.
Why do we bother to culture mastitis infections?
It aids in selecting the proper anti-microbial.