Clinical aspects of mammary gland disease Flashcards
What are the two tests you can perform to test for mastitis
- CMT (california milk test)
- SCC (want this to be below 200,000)
What is the mammary gland skin made out of?
- Thick squamous epithelium
- keratin
What is the teat end/ teat canal made up of?
- Interlocking folds- prevent bacteria from entering
- muscular sphincter
- keratin
- lymphoid tissue
Name the pathogenesis steps of mammary gland infection
The innate mechanism
- Contamination of the teat end
- invasion through the teat orifice
- ascending infection
- adherence of bacteria
- bacterial colonisation
- liberation of endotoxin
- immune response and inflammation
- milk and udder changes- pain and discomfort
- systemic disease
How does milk flow help act as a defence
the flushing action removes bacteria
How does the teat canal act as a barrier?
Keratin lined and therefore provides a physical barrier
How does the teat sphincter act as an udder defence?
constriction of the teat sphincter occludes the teat orifice after milking
How does a keratin plug act as an udder defence?
It forms during the dry period and then occludes the teat canal
How does an udder commensal act as an udder defence?
Competitive exclusion from the natural flora
How does lactoferrin act as an udder defence?
Present in milk and colostrum;
Iron-chelating and bacteriostatic
What are the three cellular defences against mammary gland disease?
- Cells (neutrophils,macrophages, lymphocytes)
- Complement system
- antibodies ( unsure of full importance)
What is the pathogenesis of the milk and udder changes?
during mastitis
- Ducts and teat cistern fills with secretions
- casein clots and serum leakage
- fibrosis, alveoli are obliterated, localised involution
What is the pathogenesis of the udder changes?
- Well demarcated zone of necrosis
- haemorrhage and subcutaneous oedema
- abscessation or gangrene
What gram are contagious pathogens?
gram positive
What gram are environmental pathogens
gram negative
this is usually more severe
What is the pathogenesis of staphylococcus aureus?
- Hides in phagolysosomes
- causes a strong inflammatory response
- Increases the SCC
- tendency to be chronic
- intermittent excretion
- gangrenous mastitis
gram pos
What bacteria is both contagious and environmental?
Streptococcus uberis
What is the pathogenesis of escheria coli?
- has grades 1-4 clinical mastitis
- chronic infection is rare
- increase in somatic cell count
- causes infection during the dry period
usually associated with hygeine issues
What three causal organisms can cause mastitis in the dry gland?
- T.pyogenes
- peptococcus indolicus
- S dysgalactiae
What is the pathogenesis of summer mastitis?
- Occurs in non-lactating glands
- Sheep head flies cause teat damage
- The damage is usually severe or irreversible
- purulent discharge
- chronic abscessation
What organisms usually cause mastitis in sheep?
- Staphylococcus aureus
- Manheimia haemolytica (Nasopharynx)
What are the 4 defining points of Strep Agalactiae?
- Gram Positive (contagious)
- Obligate parasite of the mammary gland
- Proliferative
- Highly contagious in cloths, hands etc.
What are the 4 defining points of Strep Dysgalactiae?
- Gram Positive
- Associated with teat-end damage
- Tonsillar Carriage
- Part of the summer mastitis complex
What are the 4 defining points of Mycoplasma Bovis?
- Highly Contagious
- Arthritis, Pneumonia, Otitis
- Special Culture Media, PCR
- Poor response to antibiotics
