Periparturient cow Flashcards
agents in CMT mix and what they do
- Alkylaryl sulphate lysis WBCs, releasing nuclear DNA and forming a gel
- Bromcresol purple loses its purple colour as it becomes acidic
CMT procedure
- Following the routine udder prep. routine, thoroughly clean teats and teat ends and wipe dry.
- Discard 2-3 squirts of foremilk from each quarter.
- Put approx. 1 teaspoon of milk from each quarter into each of the 4 wells in the CMT paddle.
- Tip the paddle slightly to pour off any excess milk and to create an equal volume of milk in each of the 4 wells.
- Squirt and equal volume of CMT solution into each of the 4 wells, creating an approximate 1:1 mixture of milk and CMT solution.
- Gently rotate and swirl the paddle for 5 seconds to mix milk and CMT solution.
- record result and wash paddle
Interpret the CMT result as follows:
Negative = No gel or thickening
1+ = Slight or Mild thickening (includes trace)
2+ = Moderately thick gel forms as swirl mixture
3+ = Very thick gel (center becomes elevated like a fried egg).
CMT reaction score vs SCC
normal = 100,000
T - 300,000
1 = 900,000
2 = 2,700,000
3 = 8,100,000
when to do composite milk sampling? what do we do?
- when a cow has been identified as being suspect for mastitis based on herd-level testing (ie. Somatic Cell Counts)
- combine milk collected from each quarter into a single collection vial for lab submission
pros and cons of composite milk sampling for bacterial culture
- Pros: Cheaper method to culture the cow’s udder in screening for pathogens (1 culture fee instead of 4)
- Cons: Composite milk sampling does not permit you to then move forward with treating a specific quarter with intramammary therapy based on your culture results; You know the cow has mastitis and what the pathogen is, but not necessarily which quarter is involved.
How to perform a Composite Milk Sample:
- Complete routine udder preparation (wipe off gross debris, clean each quarter with a dry paper towel)
- Strip 2-3 squirts of milk from each quarter into a strip cup, examining the milk quality after each quarter (ie. check for colour, consistency, any clots or flakes).
- Scrub each teat end with a new alcohol swab (your focus is on the teat end) in the following order: Far quarters, then near quarters. This prevents you from inadvertently contaminating quarters that you have already prepped by reaching across them.
- Remove the lid from the sample vial. Hold the lid by its margins in your palm so that the inner face of the lid is facing downwards, thus preventing any contaminants from the udder from falling onto the inner surface of the lid during your sampling. Then hold the sampling vial with that same hand.
- Being careful to not drip the milk over your fingers, strip 3-4 squirts of milk from each of the four quarters into the vial, in the following order: Near quarters, then far quarters. This order ensures that you do not inadvertently contaminate the teat ends of any quarters that you have not yet sampled.
- Secure the lid on the collection vial.
- Dip each teat in teat dip when finished.
- Label the collection vial with the owner and cow’s ID.
3rd lactation cow, ‘down in milk’
- mastitis
- metritis
- ketosis
- DA
most important question to ask about cow down in milk
when did she calve?
was it eventful?
how long have sign been going on?
other signs?
have you treated her at all?
blood BHB test for ketosis, value above which we are concerned
normal is <1.2
ketosis > 1.2
how to treat ketosis?
- oral glycol, 300mL orally, 3-5d
- off feed? B12 IM, 1-3d
- dextrose IV can help if neuroketosis
at what point after calving might we see ketosis?
often 3-21d post calving (less likely in first 3d)
at what point might we see hypocalcemia, compared to calving time?
milk fever 24h before calving to 3d post calf
at what point relative to calving should we think about dystocia, retained placenta causing clinical signs?
within 24h of calving
at what point relative to calving should we think of metritis causing issues?
up to 21d post calf
