Udder 1 Flashcards
what is mastitis? generally associated with what?
- = inflammation of the mammary gland
- Practically, associated with bacterial infection
how common is mastitis?
- Typically, 1 cow in 5 has >= 1 case of clinical mastitis per lactation
economic and medical significance of mastitis
- Often the most economically important disease on a dairy farm (~ $120 - $300 per case)
> ~ $5000 – $12,000 per 100 cows per year - The #1 reason for use of antibiotics in dairy cows
healthy teat end should have what texture?
smooth - less hospitable for bacteria
are mastitis causing agents common?
Many mastitis-causing organisms are common on the cow and in her environment
challenges for the cow for mounting an immune response to mastitis
- Blood-milk barrier limits the immune arsenal
- Milk is a difficult place for immune cells and antibodies to function
how and why does the conductivity of milk change with mastitis? what other related changes occur?
- mastitis milk is more conductive because there are more electrolytes (Na, K, Cl) present
>inflammation causes increased vascular permeability / increased permeability of blood milk barrier
> this is to let antibodies through - mastitis milk will look more like serum > better medium for immune system
notable changes in albumin, lactoferrin (what is this?) sodium, and chlorine in mastitis milk vs normal?
albumin, lactoferrin, sodium, chlorine all increased in mastitis milk
- lactoferrin is a “natural antibioitic” > binds to iron so bacteria cannot use it
mammary immune response - cellular and humoral; what do they include?
Cellular response:
* Primarily neutrophils
Humoral response:
* innate
> Complement system (opsonins)
> lactoferrin
> enzymes
> resident (e.g. LPS (endotoxin) receptors)
* acquired
> immunoglobulins (vaccination)
> memory
cells in milk; normla vs mastitis
Total cells:
-normal: < 100,000
-mastitis: > > 250,000
WBC:
-normal: >85%
-mastitis: >99%, due to massive increase in neutrophils
Epithelial cells:
- normal: <15%
- mastitis: <1%
new mastitis infections generally happen when?
New infections happen around milking
* Both contagious and environmental pathogens
general pronciples for mastitis prevention:
- Reduce bacterial challenge at the teat end
> Clean stalls, bedding, alleys
> Teat cleaning and prep at milking
> Strategic treatment of mastitis to reduce transmission
> = Prevention of intra-mammary infection (IMI) - Support immune function
> Provide cow comfort and bunk access to encourage feed intake
> Provide nutrients that fuel the immune system (e.g. vitamin E, Se)
> = Preventing IMI from developing into clinical mastitis - Reduce the severity of cases that do occur
- Also note that new infections happen around milking
difference between clinical and subclinical mastitis
Mastitis (Intramammary infection (IMI)), leads to:
-clinical = visibly abnormal milk
> milk, moderate, or severe
-subclinical = visibly normal milk but measurable infection or inflammation
major (based on pathogenic and economic impact) mastitis pathogens and their basic classifications
CONTAGIOUS:
* Staphylococcus aureus
*Streptococcus agalactiae
*Mycoplamsa spp (mostly M. bovis)
ENVIRONMENTAL:
*Coliforms:
-Escherichia coli
-Klebsiella spp.
*Strep. uberis
minor (based on pathogenic and economic impact) mastitis pathogens
*Coagulase- negative Staphylococci (i.e. other than S. aureus)
*Corynebacterium bovis
Clinical mastitis means what? what are the levels?
= visibly abnormal milk
* Mild = flakes, clots, or watery milk; normal quarter
* Moderate = abnormal milk + swollen or hard quarter
* Severe = abnormal milk, quarter and systemically ill cow
does mastitis severity depend on the agent?
- Severity is not well correlated with the etiologic agent
how much production is generally lost due to a clinical case of mastitis?
Typically 3 to 10 days of production lost (non-saleable) per clinical case
costs associated with a mastitis case
Costs include:
* milk discard
* treatment cost
* labour
* risk of drug residues
* possible risk of infection to other cows
how common is clinical mastitis per lactation? what is the case rate, typically? what is our goal?
- Typically ~ 20% (0 to 60%) of cows have >= 1 case of clinical mastitis per lactation
- Typical clinical case rate ~ 3 to 6 % of milking cows per month
- With optimal management, the goal is < 2% clinical case rate per month
on canadian dairy farms: what is the 25%, 50%, and 75% percentile number of CM cases per 100 cow years? what is our goal?
-25% of famrs have <15 cases/100 cow years
-50% of farms have <26 cases/100 cow years
-The worst 25% have >39 cases/100 cow years
> Goal: 20 cases 100/cow-years
on canadian dairy farms, what proportion of CM cases are milkd, moderate, severe?
Severity Score:
Mild (abnormal milk) 50%
Moderate (swollen quarter) 38%
Severe (systemic signs) 12%
when we recover pathogens from mastitis cases, we cannot grow anything 19.1% of the time. Why?
- often, by the time we see abnormal milk clots, the cow is already ‘winning’ (often the case with coliforms)
top 3 pathogens identified in clinical mastitis cases
-E. coli: 15.9%
-S. aureus: 15%
-other strep spp.: 12.6%
