Mastitis detection & treatment in the individual

Question 1

Individual cow vs the herd

Answer 1

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

Question 2

Importance of mastitis infections: The COW

Answer 2

• 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.

Question 3

DETECTION: Assessment of the cow

Answer 3

• 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

Question 4

DETECTION: Examination of the bovine udder

Answer 4

• 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

Question 5

DETECTION: Examination of the milk

Answer 5

• 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?

Question 6

Classification of clinical mastitis

Answer 6

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

Question 7

Mastitis infections: The CAUSES

Answer 7

• 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

Question 8

The Pathogen (bacteria) - Environmental pathogens

Answer 8

• 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

Question 9

The Pathogen (bacteria) - “Contagious” mastitis pathogens

Answer 9

• 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)

Question 10

Training farm staff to collect aseptic milk samples

Answer 10

• Samples of milk from cases of CLINICAL mastitis
• Freeze and periodic submission of a batch of samples to the lab for review or aetiology

Question 11

Mastitis infections: The TREATMENT

Answer 11

• Intramammary antibiotic
• NSAIDs

Question 12

Why is clinical mastitis treatment problematic

Answer 12

• 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

Question 13

Cow factors affecting mastitis

Answer 13

• Age
• Previous cases of mastitis
• Cell count

Question 14

Role of the Vet in clinical mastitis treatment

Answer 14

• 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

Question 15

Intramammary antibiotics

Answer 15

• cat D (narrow spec, penicillin)
• cat C (broader spec, beta-lactam & aminoglycoside, amoxicillin)

Question 16

Antibiotic treatment for CLINICAL mastitis events?

Answer 16

• 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?

Question 17

Important Elements of Treating Clinical Mastitis

Answer 17

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

Question 18

A rational approach: clinical mastitis treatment for a high cell count herd

Answer 18

• 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

Question 19

A rational approach: clinical mastitis treatment for a low cell count herd

Answer 19

• 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.

Question 20

The “high cell count cow”

Answer 20

• 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

Question 21

Mastitis infections: High Somatic Cell Count (SCC) - Dry cow therapy

Answer 21

• Measuring cell counts
• Curing infections at drying-off
• “Summer” mastitis complex

Question 22

High cell count cows – do we treat them?

Answer 22

• 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

Question 23

Antibiotic DRY COW THERAPY

Answer 23

• 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

Question 24

Internal teat sealants

Answer 24

• 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.

Question 25

SELECTIVE approach to ANTIBIOTIC dry cow therapy

Answer 25

• 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

Question 26

SELECTIVE dry cow therapy – a good approach?

Answer 26

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

Question 27

DRY COW THERAPY– review of infusion technique

Answer 27

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.

Question 28

Aseptic infusion technique: DRY COW THERAPY

Answer 28

• 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

Question 29

“Summer” Mastitis Complex

Answer 29

• 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

Question 30

“Summer” Mastitis Complex - aetiology

Answer 30

• Complex
• Arcanobacterium (Trueperella) pyogenes
• Peptococcus indolicus
• Streptococcus dysgalactiae

Question 31

Summer Mastitis Complex CS

Answer 31

• 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

Question 32

Summer Mastitis Complex - prognosis

Answer 32

• Prognosis poor, quarter often lost

Question 33

Summer Mastitis Complex - tx

Answer 33

• 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

Question 34

Summer Mastitis Complex - prevention

Answer 34

• Fly avoidance (specific pastures)
• Fly control (spray, pour-ons etc.)
• Dry Cow Therapy
• Teat Sealants (Internal and External)
• Stockholm Tar, micropore tape etc.