Aetiology, Pathogenesis and Pathology of Mastitis

Question 1

When is the cow at risk of mastitis?

Answer 1

Lactating

Dry cow

Question 2

What is the dominant pathogen in the UK causing lactating bovine mastitis?

Answer 2

Strep uberis

Question 3

What is the dominant pathogen in the UK subclinical lactating cow mastitis?

Answer 3

Coagulase negative dominates

Question 4

What is the habitat of Staph aureus? How does it enter the teat?

Answer 4

Skin and mucous membranes, enters through teat canal

Question 5

What is the problem with treating staph aureus mastitis?

Answer 5

70% of strains are betalactam positive

Question 6

How does staph aureus avoid immune response?

Answer 6

Intracellular location

Question 7

Staph aureus does not always invade udder tissues - how does it cause inflammation?

Answer 7

Due to immune response to organisms adherent to internal duct and sinus epithelium

Question 8

What are the 7 pathogenecity factors for staph aureus?

Answer 8

a-toxin
b-toxin
TSS-1 (superantigen)
polysaccharide capsule
Protein A
Enxymes
Fibronectin-binding protein

Question 9

What is the natural habitat of strep agalactiae?

Answer 9

Teat canal of udder

Question 10

What is the natural habitat of strep dysgalactiae? How does it gain entry in mastitis?

Answer 10

Outside the udder teat

Requires trauma or wound to initiate invasion

Question 11

What type of infection does strep agalactiae cause?

Answer 11

Slow, progessive, chronic

Question 12

What type of infection does strep dysgalactiae cause?

Answer 12

Not host adapted - more acute and inflammatory than others (e.g. step agalactiae)

Question 13

What is the natural habitat of Strep uberis? How does it gain entry in mastitis?

Answer 13

In the environment (faeces?)

Requires trauma or wound to initiate invasion

Question 14

What vaccine is available for E. coli?

Answer 14

Killed J5

Question 15

What key features are there about E coli in relation to mastitis?

Answer 15

AB resistance

Toxigenicity factors

Question 16

What pathogen causes a mastitis that results in a massive decrease in milk yield?

Answer 16

Mycoplasma bovis

Question 17

What is the natural habitat of mycoplasma bovis? How does it gain entry in mastitis?

Answer 17

Genital and reproductive tract

May reach the udder by haematogenous spread

Question 18

What are the 3 primary agents involved in dry cow mastitis?

Answer 18

Trueperella pyogenes
Strep dysgalactiae
Peptostreptococcus indolicus

Question 19

When do many lactating mastitis infections being?

Answer 19

During the dry period hence therapy can be highly effective in prevention

Question 20

What are the 5 main pathogens involved with mastitis in ewes?

Answer 20

Mannheimia haemolytica
Staph aureus
E. coli
Strep
Mycoplasma agalactiae

Question 21

What pathogen involved with mastitis in ewes is a notifiable disease?

Answer 21

Mycoplasma agalactiae

Question 22

What are the 4 disease process involving the mammary gland?

Answer 22

Disease of skin of teats
Pathogens transmission to young
Neoplasia
Inflammation

Question 23

What are the 3 routes of entry of microorganisms into the mammary gland?

Answer 23

1. Galactogenic
2. Haematogenous
3. Percutaenous

Question 24

What are the 3 clinical presentations of mastitis?

Answer 24

1. Peracute and life-threatening
2. Acute with or without systemic signs
3. Chronic

Question 25

What is peracute mastitis?

Answer 25

Gangenrous mastitis esp staph aureus
Toxic mastitis coliforms
Mostly occur around parturition and death can occur within hours

Question 26

How does peracute mastitis appear grossly?

Answer 26

Swollen, painful quarter
Rapid progession to moist gangrene
Dark-blue to black in colour, blistering and oozing serum
Becomes cold to touch

Question 27

How does chronic subclinical mastitis appear grossly?

Answer 27

In chronic stages, gland is hard and atrophic