Mastitis detection & treatment in the individual Flashcards
Individual cow vs the herd
The importance of an endemic disease event in the individual COW that is important to detect, diagnose and treat…
…AND the importance of this endemic disease occurring in a POPULATION meaning a need to monitor new infection rates, put in place preventive measures and review herd control plans
Importance of mastitis infections: The COW
- Individual cow welfare (pain)
- Loss of milk yield
- Reduced milk quality
- Use of antibiotic treatment
- Risk of culling (loss)
Mastitis infections have a knock on effect on shelf life of cheese, cultures for cheese, etc so v important to control from the producer and processors POV.
DETECTION: Assessment of the cow
- The cow may be systemically unwell
- Farm staff may suspect mastitis infection when the cow does not present to the parlour when she normally would
- Cow not eating?
- Cow dull, depressed?
These could be indicators of clinical mastitis infection
DETECTION: Examination of the bovine udder
- Systematic approach to examination
- All four teats and glands
- Milk/secretion
- Look and palpate
- Signs of acute/chronic inflammation
- Injury/trauma – “blood in the milk”
- Beware coldness (gangrene) (gangrene uncommon in cows, more common in sheep)
- May also note other conditions:
– Viral teat lesions, e.g., Papillomata, BHV
– Non-infectious lesions, e.g., hyperkeratosis
– Other conditions, e.g., udder cleft dermatitis
DETECTION: Examination of the milk
- Important
- Staff are looking for clots or flakes in the milk – or even a colour change
- It is a legal requirement to inspect the milk prior to sale – most often by fore-stripping to visually examine the milk – but there are other methods
- Fore-stripping prior to milking?
- In-line filters?
- California Milk Test (CMT): useful if suspect milk is abnormal but not sure, thickening of milk and reagent mixture, CMT reagent contains anionic surfactants that cause lysis of cell membranes causing release of proteins
- Conductivity?
- No detection method at all?
Classification of clinical mastitis
Mild (grade 1)
- clots or milk changes ONLY
- most common
- least likely to be of gram-negative aetiology
Moderate (grade 2)
- clots or milk changes AND swelling or heat in the udder tissue
Severe (grade 3)
- clots or milk changes, swelling or heat in the udder AND cow is unwell
Toxic
- Cow is recumbent and very sick, may occur before changes to the milk
- Most likely to be of gram-negative aetiology
Mastitis infections: The CAUSES
- Major pathogen infections
- Gram-positive bacteria
- Gram-negative bacteria
- More likely to be environmental pathogen infections (~90% infections)
- Less likely to be contagious pathogen infections
The Pathogen (bacteria) - Environmental pathogens
- Opportunistic invaders
- The cow’s environment
- Gram-positive pathogens
– S. uberis, Enterococcus spp., Bacillus spp. - Gram-negative pathogens
– Coliforms (E. coli, Klebsiella spp., Serratia spp. and many others
– Non-coliform bacteria such as Pseudomonas spp.
Klebsiella often associated with more severe clinical mastitis events in cows
The Pathogen (bacteria) - “Contagious” mastitis pathogens
- Adaption to the mammary gland (so can survive well there)
- Spread between cows at milking
- Gram-positive pathogens
– Staphylococcus aureus,
– Streptococcus agalactiae,
– Streptococcus dysgalactiae - Mycoplasma spp. (particularly in USA)
Training farm staff to collect aseptic milk samples
- Samples of milk from cases of CLINICAL mastitis
- Freeze and periodic submission of a batch of samples to the lab for review or aetiology
Mastitis infections: The TREATMENT
- Intramammary antibiotic
- NSAIDs
Why is clinical mastitis treatment problematic
- Pathogen often UNKNOWN at time of treatment
- Vast majority of clinical mastitis cases are NOT treated by a veterinary surgeon
- Cow factors, other than pathogen and choice of antibiotic, are the basis for success/failure
- Intramammary antibiotic is often administered poorly resulting in secondary infection – WIPE THE TEAT AND TEAT END WITH ALCOHOL WIPES PROVIDED
- There are several licensed antibiotic products
- Iatrogenic infection (with yeasts and moulds) are quite common
Cow factors affecting mastitis
- Age
- Previous cases of mastitis
- Cell count
Role of the Vet in clinical mastitis treatment
- Prescribe antibiotic treatment for clinical mastitis events
– These are kept on farm - Write treatment protocols
- Promote use of NSAIDs as part of clinical mastitis treatment
- Provide justification for “category C” antibiotic use?
- Must monitor treatment outcomes
Intramammary antibiotics
- cat D (narrow spec, penicillin)
- cat C (broader spec, beta-lactam & aminoglycoside, amoxicillin)
Antibiotic treatment for CLINICAL mastitis events?
- Antibiotics are worthwhile
- But not 100%…
– Antibiotics cure symptoms ~ 90%?
– Antibiotics cure bacterial infection ~50-60%? - As with many other areas of veterinary medicine, your clients will have access to non-antibiotic treatments such as rub-ins (e.g. “Uddermint”) and oral boluses (e.g. “AHV”) – respectfully CHALLENGE validity of claims – are these products supported with clinical trial data?
Important Elements of Treating Clinical Mastitis
ROUTE OF ANTIBIOTIC SHOULD BE INTRA-MAMMARY
- Little evidence that injectable (systemic) antibiotic treatment is better, or that it improves cure rate in combination
SENSITIVITY TESTING IS USUALLY NOT REQUIRED
- Resistance to antibiotic is not a feature of the majority of mastitis infections
- UK data shows 85% of S. aureus isolates are sensitive to penicillin
- Clinical mastitis events in younger cows
….in low cell count cows
…in cows that have not had clinical mastitis yet
FIRST case this lactation?
…or recurrence/repeat cases?
Individual COW factors are very important determinants of chance of cure
A rational approach: clinical mastitis treatment for a high cell count herd
- Typically, bulk milk SCC>200 cells/ml
- > 20% of cows with a high cell count
- Gram-positive pathogens predominate
– e.g., S. aureus, Enterococcus spp., S. uberis - CONSIDER narrow spectrum treatment
– Penicillin, Category D (e.g., “Ubropen”)
-> Good activity v Gram-positive
-> On label at longer course 3-5 days
A rational approach: clinical mastitis treatment for a low cell count herd
- Typically, bulk milk SCC<200 cells/ml
- <20% of cows with a high cell count
- Mixed pathogen profile, very “environmental”
- Gram-negative and Gram-positive pathogens
– e.g., E. coli, other coliforms, S. uberis - CONSIDER broad spectrum treatment
- Cephalosporin & aminoglycoside, Category C (e.g., “Ubrolexin”) as directed on label
- Generally these herds tend to have more gram-negative pathogens knocking about -> they’re controlling the gram-positives a lot better, so opportunistic gram-negatives grow.
The “high cell count cow”
- infections that do not show clinical symptoms?
- e.g. Cows infected with a major pathogen, have increased white blood cell counts in the milk, but no clinical signs of that mastitis infection
Mastitis infections: High Somatic Cell Count (SCC) - Dry cow therapy
- Measuring cell counts
- Curing infections at drying-off
- “Summer” mastitis complex
High cell count cows – do we treat them?
- Treatment of high cell count (i.e. subclinical) infection during lactation is generally associated with a POOR chance of cure, and is poor antibiotic stewardship
- Consider chronicity of infection (multiple high cell count results?), age of the cow, health status (e.g., lameness), concurrent infection (e.g., Johnes), fertility status (PD+?), have they had clinical mastitis?
– some of these cows may need to be culled from the herd? - MOST HIGH CELL COUNT INFECTIONS WILL CURE DURING THE DRY PERIOD WITH ANTIBIOTIC DRY COW THERAPY
Antibiotic DRY COW THERAPY
- Developed in the 1940’s and 1950’s and adopted in the 1960’s to control “contagious” mastitis infections
- Hugely successful
- Antibiotic DRY COW therapy treats EXISTING infection present at the end of a cow’s lactation when she is “dried off”
- chance of cure is INCREASED if we dry off cows with dry cow antibiotic AND internal teat sealant
Internal teat sealants
- NON-antibiotic dry cow therapy
- Developed in late 1990’s
- Bismuth subnitrate in paraffin base
– E.g., “Orbeseal” - Designed for use in uninfected cows
- No inherent antimicrobial activity
- Infused into the teat cistern
- Original UK work showed dramatic reduction in risk of NEW infection during the dry period using internal teat sealants
- “Compared with the antibiotic tube, quarters that received the teat sealer acquired significantly fewer new infections caused by Escherichia coli, all Enterobacteriaceae, and all major pathogens combined.”
- Trying to augment the cows natural anatomical defence - trying to reduce the risk of reinfection but augmenting her natural keratin barrier.
SELECTIVE approach to ANTIBIOTIC dry cow therapy
- ALL cows at drying-off should receive non-antibiotic internal teat sealant – huge evidence for these products in terms of reduction of new infection
- but only those cows that are likely to be infected at drying-off receive antibiotic dry cow therapy as well
SELECTIVE dry cow therapy – a good approach?
at drying-off
Uninfected cows:
- e.g. <200,000 cells/ml for the last THREE recordings before drying-off
- NO clinical mastitis in last 3 months
Infected cows:
- e.g. >200,000 cells/ml on ONE or MORE of the last THREE recordings before drying-off
- and/or clinical mastitis event in last 3 months
DRY COW THERAPY– review of infusion technique
Aseptic infusion technique
- Risk of new infection
– Coliforms (e.g. E. coli)
– Yeasts (e.g. Candida spp.)
- Important when treating clinical/subclinical inf.
- REALLY important when administering DRY COW THERAPY
- Really important as it’s the last time you’re going to touch that cow for the next 2m.
Aseptic infusion technique: DRY COW THERAPY
- Quarter(s) must be stripped or milked out completely
- Wash and dry teats (if grossly dirty)
- Dip with rapid-acting disinfectant & leave for 20-30 seconds.
- Wipe with a dry individual paper towel
- Scrub teat end with cotton wool swab soaked in surgical spirit
- Partial insertion of intra-mammary tube nozzle – infuse
- Post-milking teat disinfection
“Summer” Mastitis Complex
- a mastitis syndrome you may be called to examine and treat that happens predominantly in DRY cows
- Not mastitis that happens in the summer
- Disease of dry cows and heifers
- Transmitted by Hydrotea irritans (sheep head fly) - but not the whole story
- May occasionally occur in the winter
- Relatively uncommon now
“Summer” Mastitis Complex - aetiology
- Complex
- Arcanobacterium (Trueperella) pyogenes
- Peptococcus indolicus
- Streptococcus dysgalactiae
Summer Mastitis Complex CS
- Hot, hard, swollen, painful quarter
- Characteristic foul smell
- Cow often lame (udder so swollen and sore she can’t walk)
- Often goes undetected
- Can lead to abortion
- Pyrexic
Summer Mastitis Complex - prognosis
- Prognosis poor, quarter often lost
Summer Mastitis Complex - tx
- Intra-mammary antibiotics useless
- Systemic penicillin or derivatives
- Regular stripping
- May need to institute drainage by removing teat / cutting vertically
- Generally lose the affected quarter
Summer Mastitis Complex - prevention
- Fly avoidance (specific pastures)
- Fly control (spray, pour-ons etc.)
- Dry Cow Therapy
- Teat Sealants (Internal and External)
- Stockholm Tar, micropore tape etc.
