Udder 3 Flashcards
Strep ag. properties; how contagious? associated with what type of mastitis? what management?
- Extremely contagious
- Associated with
- a high prevalence of subclinical mastitis (i.e. many cows with high SCC)
- Poor milking hygiene; lack of post- teat dipping
- Lack of dry cow therapy
strep ag: what kind of infection if not treated? how to treat? is this a common problem?
- If untreated, very persistent infection, but…
- Very susceptible to IMM antibiotic
> 90-95% cure rate with label use of penicillin
> Treatment = Whole herd culture and “Blitz” of all infected cows with IMM, followed by improved milking hygiene, implementation of blanket DCT, and follow-up herd culture(s) - Uncommon now, but occasional epidemics
staph. aureus: what kind of infections does it establish? how do clinical signs relate to SCC?
- Tends to establish chronic infections
- Intermittent high SCC; periodic clinical flare-ups; progresses to chronically high SCC and scarring of udder
staph aureus response to antobiotics? why?
Very poor response to antibiotics
* Direct resistance
* Micro-abscesses
* Survival inside macrophages
* Lactating IMM therapy 10-40% cure rate
* Dry cow therapy 40-60% cure rate
staph aureus: what proportion of herds have at least one infected cow? prevention strategies?
- > 90% of herds have >= 1 infected cow
Variable importance as a herd problem - Prevention is critical
> Milking hygiene
> Dry cow therapy
> Segregation or elimination of infected quarters or cows
Staph aureus: diagnosis methods and problems? How to sample?
- Problem = low sensitivity
> Intermittent shedding
> Variable SCC, especially early in IMI
Culture is most sensitive
* early in the course of infection
* Pre-milking sample
* Frozen if post-milking sample
* At the quarter level (> 85% vs < 60% for composite)
* With higher inoculum volume on the plate (0.1 vs. 0.01 ml)
* 3 samples, 3 days apart, +/- pooled, higher inoculum
Mycoplasma Mastitis: Clinical Signs, response to treatment, herd level effects
- Clinical mastitis
- unresponsive to treatment
- Shifting quarters within a cow
- Epidemic in the herd
- Mastitis followed by respiratory disease and/or otitis (droopy ears) or septic arthritis in cows or calves
- Mostly seen in large herds, often after expansion i.e. mixing of large numbers of animals from various sources with some immune compromise
Mycoplasma Mastitis diagnosis
- Requires special media and longer time for culture, or use PCR.
Mycoplasma Mastitis Control
- Culture of clinical, high SCC, and fresh cows * Culling of infected cows
- Excellent milking hygiene
Environmental mastitis; reservoirs and transmission? major agents?
- Reservoir = bedding, stalls, manure; transmitted environment to cow
Major agents:
* Coliforms (gram negative)
> E. coli
> Klebsiella
* Environmental streptococci (gram positive)
> Strep. uberis
> Strep. dysgalactiae
Control of environmental mastitis
Reduce teat end contamination
* Clean stalls
* Sand bedding
* Good ventilation
* Clean floors, yards
* Milking hygiene > Pre-dip
* Nutrition to support immune function
Environmental Streptococci; what are they? what can help us diagnose and manage?
- A group of various species of varying virulence, chronicity, and response to therapy
- MALDI-TOF diagnostics will improve species-specific approaches to treatment and management
Environmental Streptococci; disease they cause and duration? antibiotic response?
- Generally cause clinical mastitis
- Duration of infection – days to weeks
- Generally respond to IMM antibiotics
> 40 - 65% cure rate
> May benefit from extra-label extended duration therapy
Coliforms; where do they live, what disease do they cause? antibiotic resopnse?
E. coli:
* Lives in manure
* Generally causes clinical mastitis
* Generally short duration of infection (1-3 days)
* Can be very severe (endotoxemia)
- Not responsive to antibiotics
> Except ceftiofur IMM? - Klebsiella is similar to E. coli but tends to establish chronic infection – high SCC +/- chronic clinical mastitis
> Traditionally associated with sawdust bedding
> More recent data > fecal
Coliform mastitis pathogenesis and outcomes
- Bacteria invade udder and grow rapidly
- Short duration (Clinical 2- 5 days, IMI 7-14 days)
- Endotoxin (gram – bacterial cell wall component) absorbed into blood – hijacks cow’s immune system (excessive inflammatory response)
- Cow can go from normal to severe mastitis in 12 to 24 h
- Outcomes: recovery, loss of quarter, loss of lactation, abortion, death
