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Mastitis, target for mastitis: 30 clinical cases/100 cows/year - Coggle…

- - - - can produce biofilm
      - gram positive cocci
      - found on udder skin and milkers hands
      - haemolytic, catalase positive and coagulase positive and produces several toxins including haemolysins and leucocidin (kills leucocytes).
      - It can persist in neutrophil lysosomal vacuoles and chronic infections often lead to the formation of scar tissue. Somatic cell counts may be raised or fluctuating and excretion of the organism from chronic cases may be intermittent
      - some strains produce β lactamase which confers resistance to β lactam antibiotics (penicillins and
        cephalosporins).
      - clinical signs from mild to gangrenous
      - poor cure rates often lead to chronic infections (can persist in neutrophil lysosomal vacuoles, also scar tissue
      - contagious pathogen
    - - Other environmental coliforms implicated in mastitis include Enterobacter, Citrobacter, Klebsiella, Serratia, Proteus, Pseudomonas, Hafnia and others.
      - klebsiella is associated with straw dust bedding
      - Pseudomonas aeruginosa is sometimes found in association with contaminated water sources, especially warm water header tanks, bore holes. Signs vary from chronic recurrent cases to acute gangrenous mastitis.
    - - Opsonisation and phagocytosis is poor, such that on occasion the organism can survive intracellularly, making antibiotic treatment important to achieve good cure rates. Certain strains appear to be more adapted to the udder, can set up chronic infections and spread from cow to cow i.e. behave as contagious pathogens. It has recently become possible to differentiate the contagious from the environmental strains through MALDI-TOF profiling.
    - - S chromogenes, S epidermidis, S haemolyticus, S simulans and S xylosus may cause intramammary infections. Because they lack the virulence factors of S aureus, they are unlikely to be clinical, but may cause mastitis in heifers or raised cell counts in well managed herds.
      - opportunistic pathogens
    - - gram positive, haemolytic coccus commonly found on teat skin
      - can be secondary to teat lesions
        
        e.g. black spot, warts or hyperkeratosis
    - - gram positive, beta haemolytic coccus is highly contagious
      - cannot survive long in the environment
      - causes a mild mastitis with high cell counts
    - - This very small, slow-growing bacteria lacks a cell wall and requires special selective culture (taking up to 14 days) or else PCR to diagnose.
      - The mastitis is usually unresponsive to antibiotic therapy, sometimes spreading to all 4 quarters and leading to agalactia even though the cow may not be systemically ill.
      - Although self-cure can occur, culling is often the best option due to the possibility of chronic infection and the risk of passing it on to other cows. Infections can be blood-borne, leading to polyarthritis and/or pneumonia. In addition, calves drinking infected milk can develop pneumonia, otitis media or arthritis although they may also become infected through respiratory spread. Interestingly, many herds with M bovis pneumonia in the calves never see it as a cause of clinical mastitis in the milking herd
    - - endotoxins (lipopolysaccharide from bacterial cell wall) are responsible for the toxic effects, but poor adhesion to the endothelium makes chronic infections unlikely
      - present in large numbers in faeces
      - clinical signs mild/self-limiting or severe/toxic/fatal
      - J5 vaccination against LPS fragment common to all strains
      - environmental pathogen
  - - - trueperella pyogenes
      - peptococcus indolicus
- - - - prolonged therapy with same/different treatment (pay attention to correct milk withdrawal periods)
      - stop tx and give more time for milk to return to normal
      - dry off that quarter (stop milking one quarter and allow it to dry up normall, leading to a 3/4 cow
      - cull the cow
      - bacteriology and sensitivity testing of the milk
  - - - amoxyclav
      - aminoglycosides
      - lincosamides
      - 3rd/4th generation cephalosporins
  - - - help decision making
    - - if high do not miss chance to cure them during the dry period
- - - - aids milk let down, flushes out bacteria laden milk
  - - - inert substance which is infused into teat canal and blocks it (bismuth sulphate)
    - - infuse antibiotic in only those with evidence of infection
        
        SCC >200,000/ml
- - - - inflammatory changes and decreased milk quality may start with SCCs as low as 100,000 cells/ml
      - An SCC of over 200,000 cells/mL in a cow indicates a high likelihood of infection
      - the higher the SCC in a herd bulk tank, the higher the prevalence of infection in a herd
        
        herd SCCs <200,000 cells/mL are desirable, lower counts can be attained
    - - the loss of milk from inflammation is directly proportional to the individual cow SCC
      - as SCC rises, milk production decreases
- - - - target under 15%
    - - requirement is under 50,000/ml, target should be <20,000/ml