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BVetMed3 - PMVPH > Pathogenesis, Pathology And Aetiology Of Mastitis > Flashcards

Pathogenesis, Pathology And Aetiology Of Mastitis Flashcards

1
Q

What disease processes can involve the mammary gland?

A

Mastitis

Neoplasia

Skin disease

Pathogen transmission to young

Trauma

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2
Q

What is galactophoritis ?

A

Inflammation of the lactiferous duct

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3
Q

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

A

Mastitis
Lameness
Fertility issues

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4
Q

What might cause milk to have a curdled appearance?

A

Mycoplasma bovis

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5
Q

Outline the structure of the mammary gland.

A 
Alveolus produces milk, 
Flows through milk duct
Into gland cistern 
Into teat cistern
Out of udder.
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6
Q

What is the difference between galactophoritis and mastitis?

A

Galactophoritis = inflammation of milk ducts

Mastitis = inflammation of mammary gland and udder tissue

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7
Q

How can microorganisms enter the mammary gland?

A

(Ascending) Galactogenic - entry via the teat canal

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

Percutaneous - entry due to trauma

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8
Q

What broad approaches can be taken to control mastitis?

A

Control pathogen entry

Control pathogen proliferation

Control tissue invasion by pathogens

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9
Q

How is the teat canal resistant to infection?

A
  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
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10
Q

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

A

Sphincter and keratin of teat

Flushing action of milk

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11
Q

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

A

Lactoferrin - iron binding proteinnthat inhibits bacteria
Lysosyme
Complement
Cytokines

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12
Q

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

A

More effective in the non-lactating gland

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13
Q

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

A

Mainly blood derived in infection

  • Neutrophils in acute inflammation
  • Later macrophages ingest
  • NK cells
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14
Q

What adaptive immune responses protect the mammary gland?

A

Lymphocytes become sensitised to bacteria, memory cells produced

Immunoglobulins - IgG mainly, also IgM and IgA

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15
Q

What does the California Milk Test detect?

A

Neutrophils and macrophages

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16
Q

What causes damage to mammary tissue?

A

Pathogens - e.g. bacterial toxins

Inflammation e.g. neutrophils, host proteases and cytokines

Reparative responses e.g. fibrosis

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17
Q

How can mastitis be categorised by time?

How does this relate to severity?

Name a pathogen that can cause all of these.

A

Peracute - life threatening

Acute - with/without accompanying systemic signs

Chronic - progressive loss of secretory ability

Staph aureus

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18
Q

What factors affect the disease process?

What doesn’t?

A

Immune status and management of animal

The pathogen DOES NOT

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19
Q

Describe the gross appearance associated with peracute mastitis

A 
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
20
Q

Describe the gross appearance associated with acute mastitis

A

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

21
Q

Describe the microscopic appearance associated with acute mastitis.

A

Initially extensive interstitial oedema
Neutrophilic infiltration of interstitium and glandular acini

Vacuolation and desquamation of acinar and ductal epithelium

22
Q

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

A

Gland is hard and atrophic

23
Q

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

A

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

24
Q

What is the most common type of mastitis?

Why is it difficult to detect?

A

SUBCLINICAL

No gross inflammation or changes in milk

25
Q

How can subclinical mastitis be identified?

A

Estimation of SCC

CMT

26
Q

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

A

Galactogenic

27
Q

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

A

Lactating mastitis

Dry cow ‘summer’ mastitis

28
Q

What are the major causes of lactating clinical mastitis?

A
  1. Strep uberis
  2. E. Coli
  3. CNS - coagulase negative staph
  4. S. Aureus (coagulase positive)

Small proportion:
Trueperella pyogenes (g+ rod)
Mycoplasma bovis
Strep dysglalacte (USED TO BE most important)

29
Q

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

A

S. uberis - skin/gut/environment

E.Coli - faeces

S. Aureus - skin + mucous membranes (nasal perineal)

30
Q

Why does staph aureus like damaged tissue?

A

Binds to fibronectin and fibrinogen on scabs

31
Q

How should you approach beta lactamase positive S aureus clinically?

A

ORBENIN- cloxacillin

32
Q

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

A

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

33
Q

How can S aureus indirectly damage udder tissue?

A

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

34
Q

What pathogenicity factors are associated with S aureus?

A 
Alpha toxin -necrotising 
Beta toxin - sphingomyelinase
TSST-1 - superantigen
Polysaccharide capsule in vivo
Protein A
enzymes: hylauronidase, lipase
fibronectin- binding protein for adherence
35
Q

Is there a vaccine available for Staph aureus?

A

NO

36
Q

Strep agalactiae

Where?
Causes?
Lancefield group?

A

Teat canal

Slow, progressive, chronic disease and fibrosis

Lancefield B

37
Q

Strep dysgalactiae

Where?
Causes?
Lancefield group?

A

Outside udder teat

REQUIRES TRAUMA

Causes acute disease and inflammatory response

Lansfield C

38
Q

Strep uberis

Where?
Causes?
Lancefield group?

A

Environmental

REQUIRES TRAUMA

NO LANCEFIELD GROUP

39
Q

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

A 
Alpha haemolysin 
CNF 1 (cytotoxic necrotising factor)
Endotoxin
Iron aquisition (lactoferrin in milk counteracts)
K types
Pili for adhesion
40
Q

What vaccine is available for E. coli?

A

killed J5

41
Q

What problems are associated with Mycoplasma bovis?

A

Milk yield dramatically decreases

beta lactams don’t work because they dont have call wall peptidoglycans

42
Q

What are the primary causes of dry cow mastitis?

A

Trueperella pyogenes

Streptococcus dysgalactae 
Peptostreptococcus indolicus (strict anaerobe)
43
Q

When do many lactating mastitis infections begin?

A

During the dry period

44
Q

Describe trueperella pyogenes (as a bacteria)

A

Small, Gram positive rods

45
Q

What are the main causes of mastitis in ewes?

A

Mannheimia haemolytica

Staph aureus

E. coli

Strep

BVetMed3 - PMVPH (8 decks)

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