Pathogenesis, Pathology And Aetiology Of Mastitis

Question 1

What disease processes can involve the mammary gland?

Answer 1

Mastitis

Neoplasia

Skin disease

Pathogen transmission to young

Trauma

Question 2

What is galactophoritis ?

Answer 2

Inflammation of the lactiferous duct

Question 3

What are the three key problems which tend to effect dairy cows?

Answer 3

Mastitis
Lameness
Fertility issues

Question 4

What might cause milk to have a curdled appearance?

Answer 4

Mycoplasma bovis

Question 5

Outline the structure of the mammary gland.

Answer 5

Alveolus produces milk, 
Flows through milk duct
Into gland cistern 
Into teat cistern
Out of udder.

Question 6

What is the difference between galactophoritis and mastitis?

Answer 6

Galactophoritis = inflammation of milk ducts

Mastitis = inflammation of mammary gland and udder tissue

Question 7

How can microorganisms enter the mammary gland?

Answer 7

(Ascending) Galactogenic - entry via the teat canal

Haematogenous - via blood e.g. TB, Brucellosis, viruses

Percutaneous - entry due to trauma

Question 8

What broad approaches can be taken to control mastitis?

Answer 8

Control pathogen entry

Control pathogen proliferation

Control tissue invasion by pathogens

Question 9

How is the teat canal resistant to infection?

Answer 9

1. Smooth muscle sphincter
2. Keratin from the epithelium containing FAs (which are bactericidal), desquaming when coated in bacteria
3. Furstenburg’s Rosette - prevents physical entry of organisms to the canal
   - FAs and cationic proteins
   - Subepithelial plasma cells producing Ig

Question 10

What physical factors contribute to the innate immunity of the mammary gland?

Answer 10

Sphincter and keratin of teat

Flushing action of milk

Question 11

What soluble factors contribute to the innate immunity of the mammary gland?

Answer 11

Lactoferrin - iron binding proteinnthat inhibits bacteria
Lysosyme
Complement
Cytokines

Question 12

When is lactoferrin most useful in the innate defence of the mammary gland?

Answer 12

More effective in the non-lactating gland

Question 13

What Cellular factors contribute to the innate immunity of the mammary gland?

Answer 13

Mainly blood derived in infection

• Neutrophils in acute inflammation
• Later macrophages ingest
• NK cells

Question 14

What adaptive immune responses protect the mammary gland?

Answer 14

Lymphocytes become sensitised to bacteria, memory cells produced

Immunoglobulins - IgG mainly, also IgM and IgA

Question 15

What does the California Milk Test detect?

Answer 15

Neutrophils and macrophages

Question 16

What causes damage to mammary tissue?

Answer 16

Pathogens - e.g. bacterial toxins

Inflammation e.g. neutrophils, host proteases and cytokines

Reparative responses e.g. fibrosis

Question 17

How can mastitis be categorised by time?

How does this relate to severity?

Name a pathogen that can cause all of these.

Answer 17

Peracute - life threatening

Acute - with/without accompanying systemic signs

Chronic - progressive loss of secretory ability

Staph aureus

Question 18

What factors affect the disease process?

What doesn’t?

Answer 18

Immune status and management of animal

The pathogen DOES NOT

Question 19

Describe the gross appearance associated with peracute mastitis

Answer 19

Swollen painful hard quarter (oedema)
Rapid progression to gangrene (necrosis)
Dark blue to black colour - blistering and oozing serum
COLD to touch
Cut surface = dark haemorrhagic lobules 
Ventral abdominal oedema 
Gland can slough off
Animal may be comatose due to toxaemia

Question 20

Describe the gross appearance associated with acute mastitis

Answer 20

Less damage to tissue
Mostly local effects: oedema, fibrin exudation, neutrophilic response
ALTERED MILK QUALITY - clots in milk

Question 21

Describe the microscopic appearance associated with acute mastitis.

Answer 21

Initially extensive interstitial oedema
Neutrophilic infiltration of interstitium and glandular acini

Vacuolation and desquamation of acinar and ductal epithelium

Question 22

Describe the gross appearance of the mammary gland in chronic mastitis.

Answer 22

Gland is hard and atrophic

Question 23

What is the difference between the effects of involution and fibrosis in chronic mastitis?

Answer 23

Involution - temporary loss of secretory function due to obstruction (e.g. by granulation tissue)and acinar stagnation
— CAN RECOVER FUNCTION if blockage resolved

Fibrosis - results in permanent loss of secretory tissue due to progressive destruction

Question 24

What is the most common type of mastitis?

Why is it difficult to detect?

Answer 24

SUBCLINICAL

No gross inflammation or changes in milk

Question 25

How can subclinical mastitis be identified?

Answer 25

Estimation of SCC CMT

Question 26

What is the most common route of pathogen entry in mastitis?

Answer 26

Galactogenic

Question 27

How can mastitis be subdivided depending on the cycle of the cow?

Answer 27

Lactating mastitis Dry cow ‘summer’ mastitis

Question 28

What are the major causes of lactating clinical mastitis?

Answer 28

1. Strep uberis 2. E. Coli 3. CNS - coagulase negative staph 3. S. Aureus (coagulase positive) Small proportion: Trueperella pyogenes (g+ rod) Mycoplasma bovis Strep dysglalacte (USED TO BE most important)

Question 29

What are the potential sources of the three main bacteria causes of clinical lactating mastitis?

Answer 29

S. uberis - skin/gut/environment E.Coli - faeces S. Aureus - skin + mucous membranes (nasal perineal)

Question 30

Why does staph aureus like damaged tissue?

Answer 30

Binds to fibronectin and fibrinogen on scabs

Question 31

How should you approach beta lactamase positive S aureus clinically?

Answer 31

ORBENIN- cloxacillin

Question 32

Why might ‘flare ups’ be seen with S aureus?

Answer 32

Intracellular location may allow it to evade the immune response and be reactivated at a later time

Question 33

How can S aureus indirectly damage udder tissue?

Answer 33

HYPERSENSITIVITY IgE can respond to S aureus even if its not invading - attached to mast cells resulting in degranulation Immune response to organisms adherent to internal duct and sinus epithelium

Question 34

What pathogenicity factors are associated with S aureus?

Answer 34

``` Alpha toxin -necrotising Beta toxin - sphingomyelinase TSST-1 - superantigen Polysaccharide capsule in vivo Protein A enzymes: hylauronidase, lipase fibronectin- binding protein for adherence ```

Question 35

Is there a vaccine available for Staph aureus?

Answer 35

NO

Question 36

Strep agalactiae Where? Causes? Lancefield group?

Answer 36

Teat canal Slow, progressive, chronic disease and fibrosis Lancefield B

Question 37

Strep dysgalactiae Where? Causes? Lancefield group?

Answer 37

Outside udder teat REQUIRES TRAUMA Causes acute disease and inflammatory response Lansfield C

Question 38

Strep uberis Where? Causes? Lancefield group?

Answer 38

Environmental REQUIRES TRAUMA NO LANCEFIELD GROUP

Question 39

What factors does the pathogenicity of E. coli depend on?

Answer 39

``` Alpha haemolysin CNF 1 (cytotoxic necrotising factor) Endotoxin Iron aquisition (lactoferrin in milk counteracts) K types Pili for adhesion ```

Question 40

What vaccine is available for E. coli?

Answer 40

killed J5

Question 41

What problems are associated with Mycoplasma bovis?

Answer 41

Milk yield dramatically decreases beta lactams don’t work because they dont have call wall peptidoglycans

Question 42

What are the primary causes of dry cow mastitis?

Answer 42

Trueperella pyogenes ``` Streptococcus dysgalactae Peptostreptococcus indolicus (strict anaerobe) ```

Question 43

When do many lactating mastitis infections begin?

Answer 43

During the dry period

Question 44

Describe trueperella pyogenes (as a bacteria)

Answer 44

Small, Gram positive rods

Question 45

What are the main causes of mastitis in ewes?

Answer 45

Mannheimia haemolytica Staph aureus E. coli Strep