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50 Cards in this Set
- Front
- Back
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What is the economic significance of mastitis?
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leading cause of loss to dairyman (~$2B annually)
$180/cow/yr 65-70% subclinical |
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What is the route by which mastitis pathogens enter mammary gland?
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bacteria enter gland via TEAT END (thru teat canal)
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What masitits pathogen is a G (+) catalase (-) cocci that causes subclinical mastitis & is almost universally sensitive to penicillin?
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Strep agalactiae
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What mastitis pathogen is a G (+) catalase (+) coagulase (+) cocci that causes acute clinical & chronic subclinical mastitis?
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Staph aureus
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What is the difference b'twn lactating & dry cow therapy?
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lactating cow therapy: intramammary AB therapy of lactating cows
dry cow therapy: intramammary AB therapy of cow at dry-off (end of lactation) |
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What is the mechanism of action of teat dips?
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teat dips: germicidal solutions applied to teat end at end of milking that disinfects teat end & acts to prevent bacterial colonization
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What are the 5 steps of the National Mastitis Council's Mastitis Control Program?
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milk cows properly using a functioning milking machine
dip all teats of all cows in an effective germicide after milking promptly detect & tx acute mastitis cases w/ recommended treatments infuse all quarters of all cows at dry-off w/ commercially available dry cow product cull chronic cases & cows not responding to tx |
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What are 3 ways that milking machines can contribute to mastitis?
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acts as fomites: transfers organism b’twn cows
damages teat end: ↑ susceptibility to mastitis causes teat impacts |
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What is the cost benefit ratio for mastitis control programs?
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control program can return $4-5 or more for every $1 invested
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Why is mastitis considered a disease complex?
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consists of host, agent, environmental factors
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What are some host factors that increase susceptibility to developing mastitis?
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anatomic: udder placement, teat sphincter integrity (most important: teat canal is major barrier to infection), teat size & shape
physiology: inc. w/ age & stress, stage of lactation, inc. milk production, genetic, nutritional (vit. A, selenium) |
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What are the contagious organisms that cause mastitis?
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contagious organisms: cow’s udder is 1º reservoir
-S. agalactiae, S. aureus, Mycoplasma spp. for contagious organisms, disinfection of teat canal via teat dipping is an effective control mechanism against colonization of teat end |
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What are the environmental organsims that cause mastitis?
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environmental organisms: coliforms, some streptococci, etc.
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What are some infecting agent factors that affect susceptibility to mastitis?
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colonization
invasiveness toxin production resistance to host defenses intracellular growth AB resistance |
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What are some environmental factors that affect susceptibility to mastitis?
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season: warm, wet conditions (coliforms); summer mastitis
housing: muddy lots, teat end doses (coliforms) bedding milk machines herd size |
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What is the pathogenesis of mastitis?
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entry via teat canal --> multiply to high numbers in mammary gland --> damage gland, chemotactic signals for PMN’s --> bacterial products & tissue damage --> inflammation (cardinal signs)
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What changes in milk are assoc. w/ mastitis?
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pH ↑: milk: 6.7 normal, blood: 7.4 normal
↑ HCO3-, Na, Cl, BSA, Ig’s, SCC (PMN’s) ↓ casein, lactose |
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What are the different forms of mastitis?
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PERACUTE: inflamed gland + sudden onset of severe systemic signs (ex. fever, depression, shivering anorexia, wt. loss)
-coliforms -most commonly treated by vets ACUTE: gland changes & lesser systemic signs of fever & mild depression -milder coliforms, S. aureus -most commonly treated by dairyman subacute: minimal gland effects & no systemic signs (usually mild Staph infection) SUBCLINICAL: not grossly detectable, but ↑ cells in milk (most common & economically important) -ex. S. aureus CHRONIC: usually subclinical, but may show periodic flare ups -ex. S. agalactiae GANGRENOUS: gangrene of gland produced when bacterial toxins produce circulatory disturbances -ex. S. aureus TOXIC: toxic changes (depression, circulatory disturbance, weakness) -coliforms --> endotoxemia -most commonly treated by vets |
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How is acute mastitis diagnosed in the individual cow?
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specific culture
clinical exam clin path |
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How is subclinical mastitis diagnosed in the individual cow?
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specific culture
indirect tests: SCC, CMT, WMT, EC, etc. |
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How is acute mastitis diagnosed in a herd?
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rate of acute mastitis: < 2% is great, < 5% is okay
-count # of cases occurring per cow day etiology, sensitivity, demographics |
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How is subclinical mastitis diagnosed in a herd?
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specific culture
SCC: most widely used tool to monitor udder health in herd whole herd culture: S. agalactiae, Mycoplasma spp., etc. goals: < 200K SCC for bulk tank |
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bacterial culture for ID of mastitis
a. reasons for failure b. considerations |
a. prior AB tx, poor lab techniques, inhibition of growth or bacterolysis in serous milk, phagocytosis by PMNs, sterile mastitis, etc.
b. contamination, freezing, composition vs. quarter cultures, interpretation (true infection vs. contamination), kinds of sample ~ 2/3 culture (+) |
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SCC
a. normal milk b. milk w/ mastitis c. benefit of test d. linear SCC format |
a. ≤ 250,000 cells/ml (MPs predominate)
b. PMNs predominate c. can assess & monitor udder health & estimate production losses d/t mastitis should NOT be used as criteria to tx individual cows d. 10 point log linear scale from 0 to 9 each point ↑ in cells assoc. w/ an equal ↓ in production goal: ≤ 3.0 |
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What is CMT used for & how does it work?
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California Mastitis Test
qualitative screening test used to detect cows w/ ↑ SCC milk mixed w/ CMT reagent, which contains detergent to lyse cells, allowing DNA to be freed DNA sticks to itself & forms a gel: ↑ gel assoc. w/ positive test w/ inflammation, milk becomes more alkaline, detected as ↑ in purple color |
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What are the quality standards for grade A milk?
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SCC < 750,000 cells/ml
bacteria < 100,000/ml by standard plate count (SPC) freedom from ABs (β-lactams) & chemicals |
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What is the importance of laboratory analysis of bulk tank milk?
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determine # & kinds of bacteria in bulk tank milk sample: different from SPC
can be thought of as 1 large composite sample of all cows in herd value in identifying herds infected w/ pathogens |
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Strep agalactiae
a. characterists b. reservoir c. transmission d. clinical signs |
a. catalase (-), Gram (+) cocci
forms chains in liquid media lancefield group B, cAMP (+) b. mammary gland & secretions of infected cows c. occurs primarily during milking d. classically, chronic & subclinical mastitis, progressing to fibrosis & atrophy of gland occasionally produces mild acute mastitis |
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Strep agalactiae
a. dx b. tx c. control |
a. specific culture, immunological tests, indirect tests
b. intra-mammary AB infusions -drug of choice: penicillin -others: novobiocin, erythromycin, cephapirin, pirilmycin, etc. -70-90% cure during lactation -dry treatment: results as good as or better than lactation tx blitz therapy -herd in trouble d/t ↑ SCC/bacterial counts: many cows infected -culture whole herd -treat positives, reculture, retest at intervals c. teat dip, dry teat, etc. |
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Staph auerus
a. characteristics b. virulence factors c. reservoir d. transmission |
a. catalase (+), coagulase (+), G (+) cocci
grows in clusters, several exotoxins, intracellular pathogen, cell walls antiphagocytic, β-lactamase, coagulase, hemolysins, etc. b. invasive (abscesses), produces toxins (ex. leukocidin), some strains resist phagocytosis by neutrophils, intracellular, can be resistant to some ABs c. infected udder & secretions d. primarily at milking |
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Staph aureus
a. clinical signs b. dx c. tx d. control |
a. serious & virulent contagious pathogen: causes peracute, acute & chronic subclinical mastitis
-leading cause of chronic subclinical mastitis -can be gangrenous b. direct culture, immunological tests, indirect tests c. peracute: systemic/intramammary ABs + supportive care acute: systemic/intramammary ABs may be indicated chronic subclinical -lactational therapy: seldom successful (< 25-50%) -greater success w/ dry cow therapy -consider culling chronically infected cows d. mastitis control program, segregation, vaccination |
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Arcanobacterium pyogenes
a. clinical signs b. tx |
a. causes sporadic cases of mastitis w/ thick purulent secretion & severe damage to gland -->firm meaty quarters
b. usually ineffective role in "summer mastitis" in Europe |
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Clostridium spp.
a. clinical signs b. transmission c. tx |
a. gangrene w/ gas production in gland; often rapidly fatal
b. gross contamination c. systemic/intramammary penicillin, fluids |
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Bacillus spp.
a. clinical signs b. transmission c. tx |
a. port wine colored secretions
b. contamination c. penicillin |
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Nocardia spp.
a. clinical signs b. transmission c. px |
a. granulomatous mastitis w/ fibrosis
b. soil organism which may be introduced w/ contaminated infusions c. poor to grave |
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yeasts
a. transmission b. prevention c. px |
a. frequent hx of prior intramammary AB therapy
b. sanitary infusions c. usually self-limiting |
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Mycoplasma
a. clinical signs b. tx |
a. severe changes in secretions, involves or spread to multiple quarters
b. none |
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What are the principles of therapy for mastitis?
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early detection: importance of mastitis detection in milking
accurate dx good case management proper use of therapeutics -determine microorganisms causing dz -determine antimicrobials likely to be effective -appropriate route & dose -appropriate duration: failure to achieve adequate duration of therapy is most common cause of tx failure |
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What is the goal of mastitis control programs?
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goal: reduce mastitis rates to acceptable levels
w/o control, 50% of cows infected in 50% of quarters control will ↓ levels ≥ 50% |
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What are some advantages to dry cow treatment of mastitis?
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cure rate greater than during lactation
damaged tissue may regenerate before freshening clinical cases at freshening are reduced salable milk not contaminated w/ drug residues |
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What are some minor pathogens that may cause mastitis?
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other Strep (ex. S. dysgalactiae, S. uberis, enterococci): primarily environmental pathogens
coagulase negative Staph (ex. S. epidermis, S. xylosis); more of a problem in goats Corynebacterium bovis |
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What is theilitis?
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inflammation of teat wall d/t trauma (no tx)
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What are ddx for blood in milk?
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rupture of vessel in gland, trauma or udder congestion, at or after parturition, Lepto
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What are causes of udder edema?
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may be physiological (at calving) or pathological (edema stresses median suspensory ligament)
no tx unless severe |
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What is tx for papillomatosis?
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cautery, surgical removal, ointments
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What is tx for cow pox?
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sanitation, ointments, etc.
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pseudocowpox
a. transmission b. tx |
a. spread in milk, can be a herd problem
b. sanitation, palliative therapy |
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ulcerative mammillitis
a. etiology b. transmission c. tx |
a. bovine herpes virus
b. spread by contact & milking c. self limiting in 6-14 wks -ointments, astringents, sanitation |
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udder impetigo, blackpox
a. etiology b. tx |
a. Staph aureus --> pustules w/ black center (contagious)
b. ointments, germicides |
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cutaneous gangrene, udder rot
a. lesions b. tx |
a. foul smelling lesions b’twn udder halves or udder & leg; occurs in early lactation w/ edema
b. tx edema, clean & apply ointment, germicide |
