Mastitis Flashcards
Methods for diagnosis of sub-clinical mastitis
Conductivity (comparison over time and between quarters)
California milk test (detects SCC elevation, crude)
Individual cow somatic cell count
Cut off value for clinical/sub-clinical mastitis?
200,000cells/ml
Two key aims in mastitis control
Cure of current infections during dry period
Prevention of new intra-mammary infections
Is fore-milking a legal requirement during milking?
Yes
Appearance of milk in mastitis
Clots
Watery consistency
Colour change (grey/yellow/red)
Common environmental pathogens in mastitis
Streptococcus uberis
Staphylococcus species (except S. aureus)
E. coli
Klebsiella
Pseudomonas
Proteus
Serratia
Gram +ve bacilli
Yeast
Protetheca
Common contagious mastitis pathogens
Staphylococcus aureus
Streptococcus agalactiae
Streptococcus dysgalactiae
Mycoplasma spp.
Features of contagious mastitis pathogens
Adaption to mammary gland
Can cause persistent infection
Spread between cows at milking
Features of grade 1 (mild) mastitis
Milk changes only
Features of grade 2 (moderate) mastitis
Milk changes
Inflammatory signs in quarter
Features of grade 3 (severe) mastitis
Milk changes
Inflammatory signs in quarter
Systemic signs
Challenges with mastitis treatment
Pathogen unknown at time of treatment
Vast majority of cases not treated by a vet
Cow and farm factors, not just antibiotic choice, affect chance of cure
Principles of lactating cow therapy
Identify bacterial pathogen
Select suitable antibiotic
Treat for suitable length of time
Ideal route of antibiotics in mastitis
Intramammary tubes
Is sensitivity testing usually required for mastitis? Why/why not?
No, resistance is not usually a feature of mastitis infections
(85% of S. aureus isolates are sensitive to penicillin)
Ideal duration of treatment with intramammary tubes in mastitis
5-8 days (extended = best chance of cure)
Are intra-mammary tubes narrow or broad spectrum?
Narrow (penicillin only) or broad
Which pathogens is dry cow therapy aimed at?
Gram positive, contagious
Aim of dry cow therapy
Treat existing infections at end of lactation
Factors to consider when deciding which cows to administer dry cow therapy to
Individual cow somatic cell count
High/low cell count herd?
Clinical mastitis history?
Bacteriology?
When administering dry cow therapy, are internal teat sealants used in uninfected or infected cows, or both?
Both
What is considered an ‘uninfected cow’ in dry cow therapy decision making?
<200,000cells/ml for last 3 recordings
No clinical mastitis in last 3 months
Dry cow therapy for uninfected cows
Internal teat sealant only
No antibiotic
Dry cow therapy for infected cows
Antibiotic with Gram +ve efficacy
Internal teat sealant
What is considered an ‘infected cow’ in dry cow therapy decision making?
> 200,000cells/ml in 1+ of last 3 recordings
And/or
Clinical mastitis in last 3 months
What can internal teat sealants be mistake for at calving?
Mastitis (the residual seal)
What is ‘summer mastitis’?
Disease of dry cows and heifers, can occur in winter
What transmits summer mastitis?
Hydrotea irritans (sheep head fly), many other things involved though
Clinical signs of summer mastitis
Hot, hard, swollen, painful quarter
Characteristic foul smell
Cow often lame
Often leads to abortion
Prognosis of summer mastitis
Poor, quarter often lost
Treatment of summer mastitis
Systemic penicillin
Regular stripping
May remove teat/cut vertically for drainage
(Intramammary antibiotics useless)
Control of summer mastitis
Fly avoidance/control
Dry cow therapy
Teat sealants (internal and external e.g. Stockholm tar/tape)
Clinical signs of acute toxic mastitis
Down cow
Cardiovascular shock signs (injected membranes, dehydrated, tachycardia, tachypnoea, cold extremities)
Temperature increase then decrease to subnormal
Not eating, drinking or milking
Mammary changes (hot, swollen, watery secretion; cow may get sick before udder pathology is seen)
Differentials for a down cow
Hypocalcaemia
Dystocia
Trauma (nerve injury)
Metritis
(Neurological/toxins)
Treatment and prognosis for severe (grade 3) E. coli mastitis
Strip quarters
Nursing (lifting if down)
Systemic antibiotics
NSAIDs
Poor prognosis (~50% will die)
Toxic mastitis/toxic shock syndrome treatment
Strip quarters
Nursing (lifting if down)
Systemic antibiotics
NSAIDs
IV fluid therapy
Oral fluids (Aggers pump into rumen, circulation poor)
What causes blue bag/black bag in ewes?
Severe mastitis (gangrenous)
Due to toxins secreted by bacteria
Symptoms of subclinical mastitis in the ewe
Increased somatic cell count
Underperforming lambs (reduced milk yield)
Indirect costs of mastitis in ewes
Reduced milk yield and quality
(–> reduced lamb growth rates)
Major causative bacteria for mastitis in the ewe
Staphylococcus aureus (contagious)
Mannheimia haemolytica
Escherichia coli (environment)
Risk factors for mastitis in the ewe
Nutrition not meeting energy requirements
Low BCS
Poor hygiene at lambing time (dirty bedding, high stocking densities)
Intramammary masses
Teat lesions
Udder conformation/teat positions
Cross suckling
Older ewes (>4 years)
Maedi Visna
Indoor lambing
Treatment for mastitis in the ewe
Broad spectrum injectable antibiotics (Amoxicillin or oxytetracycline) for 5-7 days
(Aim to save ewe, not udder)
Two most important environmental mastitis pathogens
Streptococcus uberis
E. coli
Two most important contagious mastitis pathogens
Staphylococcus aureus
Mycoplasma
Which type of mastitis (environmental or contagious) is more common in the UK and why?
Environmental because the 5 point plan has been very effective at preventing contagious mastitis
