Individual Mastitis Flashcards
what are the impacts of mastitis
Welfare
Production
Nuisance to the farmer — two groups
Time to find and treat clinical cases
Economic problem
Risk of antibiotic grades
Increased somatic cell counts — thresholds for contracts
what is mastitis
Inflammation of the udder:
- Chemical, mechanical or thermal injury
- Infection by microorganisms
what is clinical mastitis
Presence of visibly abnormal milk
Watery/thickened/discoloured with blood, pus, flakes or clots
Udder:
- Swollen, firm, redness, hot, pain, reduced size laterally
Cow normal to systemic ill
- Fever, dehydration, weakness, inappetance
what is subclinical mastitis
No visible changes in the milk
Mammary gland feels normal
how do you know subclinical mastitis is there
Rapid mastitis test (aka California Mastitis Test)
Herd test/milk test results
Conductivity meter
Saltiness?
- Some farmers do this
what is the defintion of somatic cell count
normal milk has white blood cells in it
~66-88% macrophages
~10-27% lymphocytes
~1-11% neutrophils
~0.7% epithelial cells
what is ‘uninfected’ individual SCC
< 100,000 cells/ml
what is ‘infected’ individual SCC
>200,000 cells/ml
what is infected with significant pathogens individual SCC
>300,000 cells/ml
what is a california milk test score and the approx SCC
what is the scoring of clinical mastitis
what is are the definitions of 1 clinical case, new case, recurrent case, chronic case of clinical mastitis
one clinical case = corresponds to 1 infected quarter (if 2 quarters in the same cow = 2 cases)
new case = > 8 days passed from previous clinical case
recurrent case = < 7 days passed from previous clinical case
chronic case = long term recurring persistent cases of the disease
what is a new case of subclinical mastitis
new case is an increase from <200,000 SCC to >200,000
indicates one or more quarters infected
wwhat is a chronic case of subclinical mastitis
3 or more consecutive milk records with SCC >200,000 cells/ml
‘problem’ cows
what are the sources of transmission of mastitis
what are the cow’s defence against mastitis
what are the innate immunity strucutural defences of the teat
- teat skin
- teat sphincter
- keratin
how does teat skin act as innate immunity
Healthy teat skin is coated with a protective mantle of fatty acids
Slow the growth of bacterial pathogens
- Abrasions, cracks, chapped, warts, viral infections
how do pathogens enter the mammary gland
via the teat canal
what is the role of the teat sphincter
smooth muscle
~30 mins (2h) post milking to close off
what is the function of keratin in the teat canal
Fibrous protein with lipid components
Produced by cells lining the teat canal
Bacteriostatic activity
Barrier against invading bacteria
~12-40% removed at each milking
what does damage in the teat end lead to
Hyperkeratosis
Trauma
Caused by milking machine (edema)
All lead to:
- Impaired defences
- Difficult to clean
- Uncomfortable
what is the non-specific defence of innate immunity
what are the specific immunity responses
what are the factors that affect immune response of the cow
Physiological changes:
- Dry off and calving
Nutrition:
- Vit E and selenium
- Zinc
- Vit A
- Copper
Periparturient disease:
- Energy metabolism (ketosis)
- Calcium metabolism (hypocalcemia)
- Dystocia (increase stress, probability of recumbence)
Individual cow variation
Concurrent disease
how do pathogens establish infection
cows immune system sends WBC (which increase SCC) to ‘fight’ microorganism
leads to recovery, subclinical or clinical
do subclinical cases need antibiotic therapy
not routinely
uncless you have cultured bacteria (approx 40-50%)
what factors affect antibiotic choice
Historic milk samples
- What is likely your enemy
Resistance profile of farm
- Culture and sensitivity
