Food Ani. Med- Cattle- Mastitis 2

drraythe's version from 2016-04-29 15:30

Classification of mastitis, pathogens

Question Answer
Contagious vs environmental mastitis (how do they get it, how contagious, which is more common?) CONTAGIOUS: xmitted animal to animal usually via fomites. The organisms happily live on the teat, but do NOT survive well in the environment. Can affect a high percentage of the herd, and the contagious classification is 90% of all mastitis cases. ENVIRONMENTAL: Found in environment and doesn't spread as easily cow to cow as it is poorly host adapted. This form is difficult to prevent but is much less common. type of bedding and management play a large role
which 3 organisms are most likely to affect the MILK and the lining epithelial cells of the teat?Strep agalactiae, strep dysgalactiae, coagulase-neg staph species
which 3 organisms are most likely to affect the DEEP tissue of the gland?Staph aureus, streptococcus uberis, A. pyogenes
which organisms (2 types) can infect the udder AND other body systems (septicemia/bacteremia)Coliforms-- such as E. coli and Klebsiella
what are the 3 major pathogens? 2 minor? 1 non-pathogen?MAJOR: staph aureus, strep agalactiae, mycoplasma bovis. MINOR: Staph epidermidis, Strep dysgalactiae. NON-PATHOGENIC: corynebacterium bovis

Staph aureus mastitis

Question Answer
Staph aureus how contagious? how severe is the mastitis it causes? are most cases clinical or subclinical?HIGHLY contagious, which can cause mild to severe mastitis. Most cases are subclinical though.
how much milk production does Staph aureus affect, and how does it affect SCC levels?MAJOR loss of milk production and a high SCC results
what is the most common form of xmission of staph aureus?contamination at milking-- such as equipment or milkers hands.
what is a yucky complication of staph aureus mastitis? what other problems can it cause in the udder?can cause gangrene of the udder. Also leads to fibrotic tissue and deep abscesses
explain the pathophysiology of a staph aureus mastitis? What makes it so pathogenic?invades (remember usually contamination at milking) and adheres to mammary epithelial and interstitial tissues. It also can resist phagocytosis by neutrophils, and its capsule allows it to avoid opsonization (Opsonization involves the binding of an opsonin, e.g., antibody, to an epitope on an antigen). leukotoxin allows it to kill phagocytes, and it produces beta-lactamase.
how easy is staph aureus mastitis to treat?huge pain in the ass- can resist phagocytosis AND kill phagocytes (leukotoxin), AND has a capsule to resist opsonization, AND produces beta lactamase
what toxin does GANGRENOUS staph aureus produce?alpha toxin
how are the vessels (A and V) affected by alpha toxin of gangrenous staph aureus? what clinical sign does this cause?arterial flow remains intact, but there is thrombosis in the large veins. This leads to continuous dripping of blood-tinged serum from the teat and skin around the base of the teat.
for SUBclinical staph aureus, what do you think the cow will look like? what would strip cup results be? What would SMT result be?pretty normal. normal. CMT will come back abnormal.
for clinical staph aureus, what do you think the cow will look like? what would strip cup results be? What would SMT result be?might see gross changes to udder like in gangrenous mastitis. but might be normalish looking...might see inflamamtion. The strip cup test will be positive (chunks/abnormal looking milk) and the CMT will be positive as well.
what will staph aureus look like when cultures on blood agar plate?double zone of hemolysis- (complete surrounded by incomplete)
how do you dx staph aureus mastitis? (what culture parameters)culturing a coagulase-positive staph
how do you tx staph aureus? what is considered the best therapy?beta-lactam or beta-lactam type abx are needed...but some strains have resistance to penicillin. :( ... Best therapy is dry cow therapy with long term abx in quarters
what is a particular difficulty with a cow actively lactating and has acute staph aureus mastitis?bact arent in milk, they are hiding in tissues.
min contact time for a pre-milking dip of teats before they can be milked?30sec
if you have a staph aureus mastitis positive cow, how do you go about milking them?they should be separated and milked last
what should you do with a staph aureus positive cow that is resistant to tx?cull
what are some ways to prevent staph aureus mastitis?Cleanliness during milking is key!! Have gloved milkers, pre and post dip the teats, treat all quarters of all cows at dry off. cull resistant cows. cull chronically infected cows.

Strep Agalactiae (Strep Ag)

Question Answer
how contagious is strep ag?highly
is Strep Ag usually clinical or subclinical?subclinical with periodic acute local inflammation
how is milk production affected by Step ag?SEVERE loss
most common causes of strep ag mastitis?poor milking techniques, dirty udders, personnel not wearing gloves, not segregating positive cows.
where do you find strep ag on the cow? (on the body? in the mammary gland?)only in the mammary gland, not body wide. In the mammary gland you will find it on the surface of the gland cistern and in the large collecting ducts. (does not penetrate)
what is fibrosis like with strep ag? staph aureus?STREP AG can cause chronic inflammation which might lead to MILD fibrosis of the gland. Staph aureus would cause much more severe fibrosis as it penetrates and causes abscesses.
how contagious is strep ag, or is it environmental?spreads from cow to cow
does strep ag penetrate tissues? does staph aureus?STREP AG DOES NOT PENETRATE TISSUES. staph aureus does.
with CLINICAL Strep ag-- what will the cow look like? Strip cup? CMT?she will have some inflammation of the udder (redness, heat, swelling), strip cup will have chunks (gargot) and CMT will be positive.
what test do you do to dx strep ag?do a CAMP test. This is where you have the suspected strep ag as a satellite off the mother colony (staph aureus) and if you see an arrow shaped hemolysis you know your sample of strep ag
how do you tx strep ag? prog? admin?highly susceptible to penicillin :) early tx often leads to success. intramammary tx usually effective-- systemic abx not usually necessary (it only is in the mammary gland)
Can you tx strep ag while the cow is lactating or dry? How does this compare with staph aureus?STREP AG: you can treat dry or lactating :) (staph aureus should be treated during dry cow period bc the bact are hiding in the mammary tissues)
how can you prevent strep ag?tx all quarters of cows at dry off/ all ided with strep ag, culture cows before purchase. good milking hygiene procedures, pre and post teat dipping. segregative infected cows and milk them last.

Mycoplasma bovis

Question Answer
how common is M bovis? is it contagious or envrio?less common contagious cause of mastitis
how is milk affected my M bovis?there is usually marked changes in the secretions- it can be watery to purulent and can have a sand like appearance.
how does M bovis usually start to present in the udder, and then how does it progress?usually starts in one quarter and eventually moves to all 4
does M bovis mastitis cause systemic illnesS?MASTITIS patients will not get systemically ill (only coliforms like E coli or klebsiella go systemic). However, M bovis can cause in general, in the herd, bronchopneumonia, otitis, polyarthritis....mostly in calves. And then it can cause mastitis also.
what common cause of M bovis mastitis?often incited by STRESS.
if you have a lactating M bovis mastitis cow, what should you NOT be doing with that milk, and why? What can you do to help this situation?M bovis mastitis milk should NOT BE FED TO CALVES, because they can have hematogenous spread of M bovis to other body systems. However, it can be pasteurized and then fed. (either low temp long time aka LTLT 145*f for 30min, or high temp short time aka HTST. 161*f for 15sec)
CSs: If a cow is infected with M bovis, is it systemically ill?may or may not be (he explained earlier that mastitis pts alone might not get systemically ill, but m bovis can cause systmeic infections)
if you see calves with small, multifocal to diffusly focal abscesses in the lungs... think what?M bovis
majority of mycoplasma are commensals in the resp tree. when do they cause a prob?prob when get from area they normally inhabit to an area they normally dont.
clinical signs of M bovis?may or may not be systemically ill, mult quarters affected, acute inflammation, milk often tan and sandy, be on the lookout for herd probs
what herd probs might you see with M bovis?bronchopneumonia, otitis, polyarthritis....abscesses in lungs of calves
how do you dx M bovis?you need SPECIAL MyCOPLASMA MEDIA
if you are treating mastitis in mult quarters with intramammary tx,what might happen which might lead you to think its mycoplasma?if it doesnt respond to the intramammary tx.
If you routinely culture all your cows for mastitis, what should you know about your mycoplasma cows?will show up neg-- need special medium
how do you tx mycoplasma mastitis? prog?tx is not successful :( these cows are a biosecurity risk and can be lifelong carriers. Cull infected cows to elim problem.
if you want to tx systemic mycoplasma, what should you use?MACROLIDES (there are no intramammary macrolides, hence really no mastitis tx))
how can you help prevent m bovis?clinical mastitis and fresh cows (cows recently calved and still in their first flush of lactation) should be cultured for mycoplasma (special culture medium!) and monitor bulk tank bi-weekly or monthly until prob resolved