L22: Mastitis (Maunsell) Flashcards
1
Q
2 categories of mastitis pathogens
A
Contagious
Environmental
2
Q
Major contagious mastitis pathogens
A
Streptococcus agalactiae
Staph aureus
Mycoplasma bovis
3
Q
Major environmental mastitis pathogens
A
Coliforms
Environmental strep spp.
4
Q
Mastitis pathogen that is both environmental and contagious
A
Strep. Dysgalactiae
5
Q
Teat canal sphincter open how long after milking?
A
2-4 hrs (high risk period for developing mastitis)
6
Q
Teat canal lined by:
A
Squamous epithelium
- primary means of preventing infection
- secretes keratin (low keratin highly assoc. with mastitis)
7
Q
IMI = intramammary infection
A
:)
8
Q
Natural mammary defenses**
A
Cellular immune response:
-macs, neuts, and lymphos (should be
9
Q
When is there the highest risk of IMI?
A
Beginning of the dry period
- causes clinical mastitis in early lactation
- another smaller peak at calving
- can see clinical infection in early lactation as a result of subclinical infection in the dry period
10
Q
Periparturient immune suppression period
A
About 3 wks pre to 3 wks postpartum
11
Q
Mastitis is most common dz of dairy cattle
A
:)
12
Q
Changes in milk production caused by mastitis
A
Subclinical: 10-30% loss; most costly aspect!
Clinical: variable losses
Effect depends on stage of lactation, duration, season, lactation #, organism
13
Q
Costs assoc. with mastitis
A
Dec. milk yield* Discarded milk* Culling and death losses Tx and vet fees Labor Control costs Dec. milk quality premiums Clinical mastitis: other periparturient dz, poor reproductive performance
14
Q
Subclinical mastitis detection at cow level
A
SCC:
- California mastitis test
- Individual SCC: IMI >200,000 cells/ml
15
Q
Detection of clinical mastitis at the milking parlor
A
1) Fore-stripping
- Goal = stimulate milk let-down and detect mastitic milk
- prevents mastitic milk entering bulk tank
2) in-line electrical conductivity (increase assoc. w/ mastitis)
3) Increase in SCC if in-line monitoring
4) monitor milk production for sudden drop
16
Q
Detection of clinical mastitis on PE
A
- evaluate milk for color, consistency, garget (clots)
- observe/palpate glands for inflammation
- perform PE to detect systemic involvement
17
Q
Detecting what pathogens are involved with individual cow milk cultures
A
- collect before treating
- collect aseptically
- proper transport and storage
- can’t differentiate coliform and gram + mastitis clinically, so must use selective culture plates
18
Q
Antimicrobial sensitivity testing
A
- guides antimicrobial selection for herd protocols
- doesn’t always translate to susceptibility in vivo
- has limited value in individual cases
- no benefit with coliform or chronic S. Aureus (no correlation b/w sensitivity and tx efficacy)
19
Q
Interpreting milk cultures that don’t grow
A
- Occurs in about 30% of clinical or high SCC samples
- can be false negative if improperly sampled, low bacterial numbers, intermittent shedding, microbial inhibitors present, fastidious organisms, or interpreted too early
- true negative if IMI cleared before sample collected, or due to non-infectious cause**
20
Q
Legal limit for bulk tank SCC
A
750,000 cells/ml
- avg. of >200,000 indicates some IMI in the herd**
- should evaluate at least 4 samples over 4 weeks
- strong negative correlation of annual average BTSCC and milk production
21
Q
Standard Plate count (SPC)
A
- performed on bulk tank milk evaluation
- total aerobic bacterial #
- legal limit is 100,000 cfu/ml
- goal is
22
Q
Bulk tank milk culture for specific pathogens
A
- IDs the predominant bacterial groups in the herd
- if environmental organism, assoc. with dirty udders/equipment, inadequate cooling
- if contagious organism, assoc. with IMI
- should take consecutive samples over 4 days
23
Q
Properties of contagious mastitis
A
- reservoir = infected udders*
- spread from cow to cow at milking time via fomite, or droplet propulsion through teat canal*
- often subclinical, chronic
- Major pathogens: Staph aureus, strep agalactiae, Mycoplasma spp., strep dysgalactiae (also environmental)
- minor pathogens: corynebacterium bovis
24
Q
Strep agalactiae
A
- usually causes chronic, subclinical mastitis**
- lives in mammary gland, doesn’t survive well in env.
- influx of neuts into gland –> great increase in SCC
- shed in high #s –> increased BT SPC
- chronic infection leads to involution of affected areas, fibrosis
25
Staph aureus
- usually leads to chronic, subclinical mastitis**
- can cause clinical mastitis but usually mild (rarely gangrenous)
- recurrent cases common
- bacterial toxins/enzymes --> tissue damage and fibrosis, abscesses and microabscesses
- resists phagocytosis
- produces beta-lactamase
- inhabits mammary gland, skin (damaged teat skin)
26
Reservoirs and transmission of Staph aureus
Reservoirs: chronic subclinical cases, purchased cattle (esp. Heifers)
Transmission: milking, horn flies, cross-suckling of calves
27
Mycoplasma mastitis properties
- mostly M. Bovis
- highly contagious
- causes chronic subclinical mastitis
- often affects multiple glands**
- outbreaks of clinical mastitis occur in naive herds, prepubertal heifers, dry cows
- can cause arthritis, pneumonia**
- causes terrible gritty, orange brown milk secretions, however cow not usually systemically sick
28
Major environmental pathogens
Streptococcus uberis
Strep dysgalactiae (also contagious)
Coliforms
29
Minor environmental pathogens
```
Coag-negative staphylococci
Others:
-Trueperella pyogenes
-Prototheca
-E. Faecalis
-Pseudomonas aeruginosa
-Nocardia species
-Serratia marcescens
-Fungi/yeasts
```
30
Organisms that cause coliform mastitis
E. Coli
Klebsiella
Enterobacter spp.
31
Percent of coliform mastitis cases that are clinical?
10% subclinical
60% mild to mod. Clinical
30% severe clinical
Chronic infections uncommon
32
Pathogenesis of coliform mastitis
- infection may be cleared quickly but inflammation may persist
- endotoxin release --> activation of inflammatory pathways and vasoactive mediators --> endotoxemia
- high SCC may be protective
- immune impairment in periparturient period, heat stress can predispose
- if severe, can have high mortality
33
Most important environmental pathogens in terms of # clinical cases in US
Environmental streptococci:
- Strep uberis
- Strep dysgalactiae
- Strep spp.
- Enterococcus spp.
40-50% IMI are clinical (however usually mild to moderate)
34
Environmental streptococci
- present in skin, GI, and urogenital tract
- ubiquitous in dairy environment, esp. In organic bedding (ie. Straw)
- can spread once in the udder
- strep dysgalactiae can colonize teat ends
35
Environmental mastitis prevention
- manage environment to decrease bacterial load
- milk clean, dry teats
- pre-dip
- decrease exposure at high risk times
- boost host defenses
- manage environment to decrease teat injuries
- good infusion technique
36
Contagious mastitis prevention
- milking hygiene
- post-milking germicidal teat dipping
- teat end condition
- milking procedure machine maintenance
37
Most effective method for control of contagious pathogens
Post-dipping
38
Pre-dipping procedure
- removes environmental bacteria that have contaminated teat end since the last milking, before teat canal opened
- apply to clean teats
- use approved germicidal predip
- allow at least 30 seconds contact
- wipe dry: prevent dip residue in milk
39
Methods of minimizing exposure between milkings
- udders should be in contact with clean, dry bedding
- barrier dips
- fresh feed/turn out to clean lots after milking
40
Dry cow therapy
Goal = minimize new infections in the early dry period
- limited efficacy against coliforms
- doesn't protect against IMI in late dry period
41
Methods to boost host defense mechanisms
- adequate nutrition, esp. vit. E and selenium
| - vaccination for Gram - bacteria, and to reduce severity/incidence of clinical coliform mastitis
42
Antimicrobial tx during lactation
- generally only for clinical mastitis
- high cure rate for Strep. Agalactiae
- moderate response for environmental Strep spp.
- poor response for Staph aureus
43
Antimicrobial tx in the dry period
- high efficacy for elimination of subclinical IMI and prevention of new IMI in the early dry period
- should infuse all glands of all cows at dry-off
- drug should have slow release
- drug choice depends on: if effective against GP spectrum, sensitivity data, and clinical efficacy in the herd
44
Abx approved for intramammary use in non-lactating dairy cattle
```
Ceftiofur
Cephapirin benzathine
Cloxacillin benzathine
PenicillinG procaine
PenicillinG procaine + Novobiocin
```
45
Antimicrobial selection based on:
-pathogen ID
-milk withholding
-hx of clinical efficacy in that herd
(Should reassess regularly)
46
Tx of clinical mastitis with severity score of 1 or 2
1) IMM abx
2) +/- oxytocin AT MILKING if painful to milk
3) anti-inflammatories for moderate CM (ie. Banamine, aspirin, dex, isoflupredone acetate)
47
When to use abx for mild/moderate clinical mastitis (coliform, G+, mycoplasmal)
- coliform mastitis: usually NOT indicated (most infections self-resolving)
- gram + mastitis: decreases time to resolution, chronic infection rate, clinical relapse rate
- mycoplasmal mastitis: abx INEFFECTIVE
48
Differentiation of coliform and GP mastitis
- can't differentiate clinically
- herd hx and infection patterns with frequent monitoring
- on farm milk culture
49
Treating severe clinical mastitis
-decrease systemic effects of endotoxin/shock (fluids, anti-inflammatories)
-abx (IMM + parenteral)
+/- oxytocin at milking
50
Gangrenous mastitis: cause and CS
- uncommon
- S. Aureus, Clostridium spp. (GN) bacterial toxins --> severe vasoconstriction, ischemia, necrosis
- results in severe clinical mastitis, distinctive appearance of affected gland (discolored, cold, oozing serum, serosanguinous secretions)
51
Tx/prognosis of gangrenous mastitis
Tx: aggressive supportive therapy, systemic abx, +/- amputate teat to assist drainage +/- mastectomy
Poor prognosis
52
Indications for teat amputation
- Severe gangrenous mastitis
- severe chronic clinical mastitis w/ systemic illness or abscessed gland
- better drainage is needed, and gland wouldn't have returned to normal production
53
Procedure of teat amputation
2% lidocaine ring block around base of teat (unless gangrenous) +/- teat cistern infusion with tourniquet, xylazine sedation
Clamp teat distal to venous plexus, amputate below clamp, drain and flush gland
54
Chemical destruction of quarter
- cause affected gland to permanently cease milk production via infusion with chemical that destroys mammary epithelium
- indications: chronic non-responding mastitis, don't want to cull the cow
- do NOT use in gangrenous/toxic mastitis, or where teat already amputated
55
Procedure for chemical destruction
- strip gland, infuse with chemical (ie. Undiluted chlorhexidine, formalin)
- swelling and discomfort caused at 24-48 hrs and may become systemically ill (can used NSAIDs)
- gland gradually atrophies as inflammation dies down, while other quarters remain functional
56
Managing mastitis in ORGANIC herds
- mostly the same
- teat dips and sealants permitted
- segregate infected and clean cows
- good herd mastitis monitoring program essential (BTSCC, frequent BT cultures)
- segregate chronic subclinical mastitis until culling
- CM: cull, treat conventionally and move to non-organic herd, or tx without abx if mild to moderate
57
Mastitis in BEEF cattle
- S. Aureus most common (also CNS, Strep, A. Pyogenes)
- causes decreased weaning weight when multiple glands affected
- chronic IMI --> involuted (dry) glands
- should inspect udders at least once a year
- ID +/- cull cows with dry quarters or with clinical mastitis in more than one gland
- if there is a large outbreak, look for teat lesions that could indicate foreign dz or other teat problems
58
Dx of mastitis in small ruminants
- PE: similar to cattle, may have lameness on affected side or refuse nursing
- Milk culture
- SCC (direct SCC or CMT)
59
More overlap between non-infected and infected glands for goats than for cattle
:)
60
Major Pathogens for mastitis in small ruminants
S. Aureus
Mannheimia haemolytica
Mycoplasma spp.
61
Minor pathogens for SR mastitis
Coag-neg. staph
| -very common
62
Environmental pathogens assoc. with SR mastitis
- coliforms
- environmental streps
- Arcanobacterium pyogenes
Misc: Lentiviruses
63
Most common isolate of CM in SR
Staph aureus
- can cause mild, severe, or gangrenous mastitis
- chronic IMI --> involution, large fibrinous nodules, abscesses
64
Mannheimia haemolytica mastitis in SR
- causes severe or gangrenous CM in sheep
- trans. By resp. Tract of suckling lambs
- bacteremia and localization to joints, etc.
65
Mycoplasma spp. mastitis in SR
- highly contagious herd infection
- sudden marked decrease in production
- CM in BOTH glands
- Chronic IMI = reservoir for the herd
- doesn't respond well to tx (culling best)
66
Syndromes associated with Mycoplasma spp. Infection (besides mastitis)
- septicemia in young kids
- resp. Dz in older kids
- arthritis any age
- conjunctivitis
67
Mastitis control in dairy sheep and goats
- similar to cattle
- prevent new IMI by post-milking dips, reduce fomites, milk clean dry teats, segregate infected animals, and maintain biosecurity
- eliminate existing IMI with intramammary abx (can use cow products), dry cow therapy
68
Mastitis in meat and fiber sheep/goats
- most common 2-3 wks PP and after weaning
- weaning mgmt important
- inspect udders at handling times prior to breeding and cull animals with chronic mastitis
