Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
69 Cards in this Set
- Front
- Back
|
A definitive diagnosis of mastitis causing organisms can only be made via ______
|
-culture
|
|
|
Milk culture
-types |
Individual animal culture
-composite sample -quarter sample String Sample Bulk tank mixture culture |
|
|
Composite milk culture
-what's tested |
-some milk from each quarter
|
|
|
Quarter sample
-what's tested |
-milk from 1 quarter only
|
|
|
Individual animal milk culture
-use |
-want to know which animals are infected with what pathogen
|
|
|
Individual Animal milk culture
-possible results (meanings) |
No growth
-animal is free of mastitis -false negatives Growth of a pure culture -animal has clinical infection -false positives Growth of multiple colony types -contamination |
|
|
Individual animal milk culture
-reasons for false negatives |
-pathogen below detectable limit
-pathogen cleared but abnormal milk not resolved -special media required -antibiotics/inhibitors in milk -sample mishandling |
|
|
Individual animal milk culture
-advantages |
-info about individual animal
-isolates can be used for susceptibility testing -test sensitivity better than for bulk tank |
|
|
Individual animal milk culture
-disadvantages |
-cost
-labor -time |
|
|
String samples
-reason to use |
-which groups are infected?
or -what are the predominant pathogens within a group? |
|
|
String sample
-advantages |
-less labor/cost
-improved test sensitivity over bulk tank culture |
|
|
String sample
-disadvantages |
-difficult to collect without cross contamination
-cannot co-mingle groups post-collection -may require individual animal cultures to follow up |
|
|
String samples
-methods of collection |
-in-line drippers (poor)
-multiple bulk tanks (require multiple days to collect several strings) |
|
|
Bulk tank milk culture
-reason to use |
-Is a specific pathogen present/absent in the herd?
-What are the predominant bacterial groups in the herd? |
|
|
Bulk Milk Tank culture
-how often should sampling take place? |
As often as possible, depending on;
-size of herd -likelihood of downgrade -presence/absence of contagious pathogens -owner's tolerance for risk |
|
|
Key to quality results with sample collection
|
-aseptic technique
|
|
|
Sample collection
-reasons for contaminated samples |
-dirty teat ends
-wet udders -milker's hands -non-sterile containers |
|
|
Bulk tank milk sample
-how to properly collect |
-agitate tank for 10-15 mins before sampling
-use sterile dipper to collect milk from top of tank (not milk outlet) -transfer sample to a sterile collection vial ****only liscenced milk haulers or dairy owners may handle bulk tank milk (no vets) |
|
|
How to properly collect an individual cow milk sample
|
-person collecting milk should wear latex/vinyl gloves (change gloves often)
-prep the cow as usual (pre-dip, wipe) and dry the udder -clean teat ends with an alcohol wipe (far, near, near, far) -sample teats closest to you first -discard 1-2 squirts of milk and hold collection vial at 45 angle |
|
|
Proper Sample handling post-collection
|
-cooled/refrigerated immediately
-delivery to lab as soon as possible (ship overnight on ice or freeze) |
|
|
Freezing milk samples
-effects |
-Staph. and Strep. isolations not affected
-E. coli sensitivity for isolation may be reduced but usually there is so much E. coli when present that it can still be detected -Nocardia sp. can become difficult to isolate, but they are rare |
|
|
When using proper sample collection what % of individuals can you expect contamination?
|
-10%
>20% = poor collection technique |
|
|
Mammary gland
-normal defense mechanisms |
Physical barriers
-teat end (sphincter) -keratin lining of the teat canal Immune factors -non-specific immunity (neutrophils, macrophages, lactoferrin, lactoperoxidase) -specific/acquired immunity (lymphocytes, immunoglobulins) |
|
|
Keratin lining of teat canal
-reasons why good for mammary defense |
-adsorption
-desquamation -fatty acids |
|
|
How does mastitis develop?
|
-organisms enter the teat duct and multiple in the streak canal
exception = mycoplasma sp. (hematogenous) |
|
|
Teat end lesions
-cow risk factors |
-teat shape
-teat position on udder -production level -stage of lactation -parity |
|
|
Teat end leasions
-milking risk factors |
-pre-milking prep
-machine on-time -liners |
|
|
What does it usually mean if multiple cows have keratin plugs in the herd?
|
-milking machine issue
or -prep issue |
|
|
Mastitis
-things that could go wrong related to the epidemiological triad |
Host
-damaged teat ends -low immunity Pathogen -toxin production -herd infection status Environment -poor housing/hygiene -improper milking procedures |
|
|
Mastitis
-pathogen classifications |
-contagious
-environmental |
|
|
How can environmental pathogens be considered contagious?
|
-can contaminate milking units ---> contagious spread of pathogens
|
|
|
Mastitis
-contagious pathogens |
-Staph. aureus
-Strep. agalactiae -Mycoplasma |
|
|
Mastitis
-main environmental pathogens |
-E. coli
-Non-aureus staph -strep. dysgalactiae/uberis |
|
|
Culling
-is it a veterinary decision? |
-NO, it's a management decision
|
|
|
Culling
-recommended with consideration of |
-animals age
-chronicity/number of mastitis episodes -production -lactation stage -co-morbidities -genetic value |
|
|
Staph. aureus
-clinical presentation |
-chronic clinical mastitis
-poor response to lactating cow therapy -poor efficacy of dry cow treatment -incidence of clinical mastitis rises with lactation number and days in milk -palpable scar tissue in quarter -gangrenous mastitis |
|
|
Gangrenous mastitis
-clinical signs |
-anorexia
-dehydration -fever -teat/distal gland -watery sanguinous -gas present -udder sloughing |
|
|
Staph aureus in herd
-what to do |
-cull chronically infected cows
-segregate infected cows (free stalls, stall barns) -if possible dry off infected cows w/in 80 days of calving --treat all 4 quarters with dry cow antibiotic -screen all purchased animals and animals that have left the grounds for fairs/shows -having milking equipment function evaluated -establish proper milking routine -dry treat all quarters of all cows -evaluate housing conditions for sources of teat injury -establish routine culture program |
|
|
Staph aureus
-cows that should be culled |
-mastitis over > 1 lactation with marginal milk production
-SCC >400,000 over 2 lactations -3+ treatments without clinical sign reduction |
|
|
Staph aureus
-parts of the milking machine that should be examined |
-vacuum
-pulsator -detach settings -inflation conditions |
|
|
Strep agalactiae
-clinical presentation |
-BTSCC consistently high
-low clinical infection rate (many subclinical) -poor correlation b/n individual SCC and clinical cases (many subclinical) -high incidence of non-functional quarters in fresh heifers -therapeutic response to clinical cases is good |
|
|
Herd is Strep agalactiae positive
-what should be done |
Depends on severity (loss of milk marketability)
-cull/antibiotics (still susceptible to beta-lactams) |
|
|
Strep aglactiae positive
-emergency situation = -what to do |
= SCC > 750,000
-cull certain 3rd lactation cows that meet certain criteria --mass treat all lactating cows with lactating cow antibiotic (penicillin) ---culture entire herd and any heifers/cows that freshened 3 wks post mass treatment ----treat any remaining Strep ag infected animals and separate into separate string -----resample infected string 3 wks after 2nd mass treatment ------cull any animals still infected |
|
|
Strep ag
-3rd lactation cows that should be culled characteristics |
Strep ag culture positive and:
-have SCC > 1.5 million for 3 months or -previous Hx of chronic mastitis or SCC > 2 million or -less than 4 functional quarters -clinical quarters that don't respond to therapy |
|
|
Strep ag
-what should be done to cows within 80 days of calving |
-dry off
-treat with dry cow formulation |
|
|
Strep ag
-short term action SCC -what to do |
-SCC = 300,000 - 600,000
-cull certain 3rd lactation cows that meet certain criteria --cows within 80 days of calving should be dried off and treated with dry cow formulation ---treat any remaining Strep ag infected animals and separate into separate string |
|
|
Strep ag
-long term management SCC -plan |
-SCC = 200,000-400,000
-identify all infected cows and treat, cull, or dry off -culture all purchased animals -follow recommended milking procedure -treat all quarter at dry-off -continue monitoring |
|
|
Mycoplasma sp.
-unique in diagnosis how? |
-will not grow on routine culture
|
|
|
Mycoplasma sp.
-clinical presentation |
-High SCC
-no gland swelling -can affect all 4 quarters -not responsive to antibiotics (no approved drugs) -can approve or go subclinical -many don't show signs -Hx of respiratory dz, joint infection, inner ear infection |
|
|
Mycoplasma sp.
-long term infection generally seen where |
-calves fed waste milk
|
|
|
Mycoplasma sp. (+) herd
-what should be done |
-have the organism typed to make sure it is mastitis causing
--repeat bulk tank culture ---collect string samples to determine herd distribution of infection ----submit individual milk samples (cull all positives) -----backflush milking unit after every cow ------monitor fresh cows/heifers and new additions -------submit 8-10 bulk tank samples following the last positive tank sample |
|
|
Contagious pathogens action steps
-summary |
-ID infected animals
-separate infected animals -review parlor procedure -review parlor procedures again |
|
|
When reviewing parlor procedures, what should you focus on?
|
-clean, dry cows
-pre-milking teat dips -procedural timing -disinfection b/n animals |
|
|
Primary environmental pathogen
|
-E. coli
|
|
|
Coliform bacteria
-signalment |
-< 60 days in milk
-high producing older cows -Low SCC |
|
|
Why are older cows more susceptible to coliform infection?
|
-more exposure to milking units causing more teat end damage
|
|
|
Why are herds with a low SCC predisposed to coliform infection?
|
-possibly due to less circulating antibody in the blood
|
|
|
Coliform bacteria
-endotoxemia presentation |
-anorexia
-depression -elevated body temp (early) --> decreased body temp (late) |
|
|
Coliform bacteria
-outcome |
Varies from death to spontaneous recovery
|
|
|
Coliform bacteria
-how to handle |
Bedding management
-clean/comfortable stalls -inorganic bedding material -increased space per cow in dry lots Keep cows standing post-milking (provides time for teats to close after milking) -provide feed and water Careful use of water during milking |
|
|
Coliform bacteria
-therapy |
-systemic antimicrobials
-NSAIDs -Fluid therapy (hypertonic saline + oral fluid) -calcium therapy DON'T give intramammary antimicrobials and frequent stripping/oxytocin |
|
|
Environmental Staphylococci
|
-non-aureus staph.
-coagulase negative -normal skin flora |
|
|
Environmental Staph.
-clinical presentation |
-can be the most common mastitis pathogen in some herds
-high prevelance in 1st lactation animals -high spontaneous cure rate -moderate elevation in SCC |
|
|
Environmental Staph.
-what should you do |
-confirm presence via culture
Considerations: -implement use of post milking teat dip -100% dry cow therapy -fly control -stall/environment management |
|
|
Environmental Streptococci
-sources of infection |
-water
-fecal -bedding |
|
|
Environmental Strep.
-farm conditions that increase likelihood of infection |
-overcrowding
-poorly maintained free stalls -access to free standing water |
|
|
Environmental Strep
-clinical presentation |
-high # of cows infected
-very high BTSCC -mastitis in early dry period (in absence of dry cow therapy) -high numbers of 1st lactation animals developing mastitis in immediate post-partum period |
|
|
Environmental Strep.
-what should you do |
Manage environment, focusing on high risk groups of animals:
-early dry cows -peri partum cows Clean, dry bedding (inorganic material) Keep standing after milking |
|
|
Environmental Pathogen
-summary of action steps |
-confirm organism via culture
-discuss environmental management -discuss appropriate dry cow therapy -revist parlor proceedures |
