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Re: [FH] Re: ASA questions??

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  • Jean
    My cardiologist prescribed 1/4 of an 81 mg tablet twice a week (simpler and I suppose slightly less frequent than every three days), and if he tolerated it
    Message 1 of 7 , Mar 4, 2009
      My cardiologist prescribed 1/4 of an 81 mg tablet twice a week (simpler and
      I suppose slightly less frequent than every three days), and if he tolerated
      it after a month to up it to 1/2 of an 81 mg tab twice a week. (He was
      starting ASA after not tolerating plavix in November.) I was considering
      replying to your initial email about a whole baby aspirin every three days,
      because it sounded like a lot to me as well (and I think I most commonly see
      1/4 of an 81 mg mentioned), but then I came across the following (pasted
      below message) from http://www.vetinfo4cats.com/catmed.html . My impression
      based upon this is that an entire 81 mg tablet IS on the high end, but not a
      complete anomaly in prescribing.

      I think the most common issue with ASA (and plavix) is that it's hard on the
      stomach. ASA seems to be better in this regard than plavix, probably in part
      because it's dosed every three days instead of daily. I believe it can also
      cause kidney/liver issues, just like most other heart meds; for plenty of
      cats, that's not an issue. (My boy's ALT, a liver enzyme, went through the
      roof after a week and a half on enalapril; it's part of the reason for
      regular bloodwork.) Uncontrolled or internal bleeding is a risk with any
      blood thinner, I think (in researching Patches' condition, I've heard
      infrequent stories of internal bleeding in cats on both ASA and plavix, but
      overall it seems more frequent with plavix.); the alternate risk of not
      being on ANY blood thinner is the risk of clotting (which blood thinners
      don't guarentee won't happen regardless, it's just thought to lower the
      risk).

      The nattokinase that Carol mentioned sounds like doesn't have the same risk
      of stomach side effects as ASA or plavix, and it certainly doesn't have the
      toxicity of ASA if not dosed or metabolized properly. If you and your vet (I
      forget, are you with a regular vet or cardiologist? Vets probably have far
      less experience dosing ASA, particularly for cats; it's historically been
      used more often in dogs than cats. Regardless a cardiologist will have more
      experience with cats on their preferred blood thinner, and the dosing.) do
      decide to try ASA, I would definitely recommend starting on a lower dose to
      see how your baby initially tolerates it, and looking into dosing
      recommendations before settling on a final dose.

      The relevant portion of the above link (note that it was written in 2001 -
      standards may have changed, and many - by no means all - cardiologists have
      switched to plavix as the first-line blood thinner since then):
      *Aspirin dosage for cats*

      *Question: *I believe the aspirin dosage you reccommend for cats is
      incorrect on this page: http://www.vetinfo.com/catortho.html

      You suggest 10mg/lb, but every other source I can find suggests 10mg/kg.
      That makes the dosage you suggest more than twice the common
      reccommendation. Here are some other resources:

      http://oacm.uvm.edu/oacm/cat.htm
      http://www.valleypetnews.com/venerable_vet_i.htm

      *Answer: *Mark-

      Thank you for being concerned enough to write to us about the dosage for
      aspirin.

      There are published studies indicating that aspirin is safe when dosed from
      10 to 25mg/kg every 48 to 72 hours and one study indicating no problems when
      it was dosed at 162mg/cat once a week. We use up to 10mg/lb in our
      practice, even though it is at the higher end of the dosage scale. We
      usually do not exceed 81mg per cat and I probably should indicate that in
      our answers online, since this is often closer to 5mg/kg in large cats.

      Mike Richards, DVM 10/15/2001



      Good luck!

      Jean


      [Non-text portions of this message have been removed]
    • taclea
      Thanks everyone for replying. I did some reading and found some google book excerpts of vet medicine textbooks that indicated that asa in doses of 25mg/kg
      Message 2 of 7 , Mar 4, 2009
        Thanks everyone for replying. I did some reading and found some google book excerpts of vet medicine textbooks that indicated that asa in doses of 25mg/kg twice weekly did not show toxicity. My cat is 16lbs so 81mg is just over 10mg/kg. I mentioned my concern about asa for cats and my vet said the dose of 81mg every 3 days was safe. I will follow with again about this.
      • nala_zq
        ... My cat tolerated plavix for roughly 18 months. It was always given to her after she had eaten. She did not appear to have tummy upset issues. The
        Message 3 of 7 , Mar 5, 2009
          > I think the most common issue with ASA (and plavix) is that it's hard on the
          > stomach. ASA seems to be better in this regard than plavix, probably in part
          > because it's dosed every three days instead of daily.

          My cat tolerated plavix for roughly 18 months. It was always given to
          her after she had eaten. She did not appear to have tummy upset
          issues.

          The problem with high doses of aspirin in kitties, more so
          than the tummy upset is that kitties lack an enzyme, produced
          by the liver (glucuronyl transferase) that is required to metabolize
          not only aspirin but also other NSAIDs. This means that it takes longer
          for aspirin to clear the kitty's system (3 day dosing) and it makes it
          much easier to overdose a kitty. Especially a compromised
          kitty.

          If there are concerns, then one could further consult with one's vet
          or have a liver panel done to see whether there are problems.

          Additionally some NSAIDs can interfere with the function of ACE inhibitors.
          ACE inhibitors work, in part by dilation of blood vessels in the kidneys and
          some NSAIDs interfere with this dilation. I don't recall whether aspirin is one of
          these specifically.

          A baby aspirin is typically 81 mg of aspirin.

          As far as a specific dose, the FATCAT study that is looking at the effect
          of plavix vs. aspirin for prevention of a second clot in a group of kitties
          that have already experienced a clot is:

          "clopidogrel/plavix (18.75 mg PO q 24 hours) or aspirin (81 mg PO q 72 hours). The dosages chosen for the study drugs are based on the standard accepted dosing regimen for aspirin and preliminary data from clopidogrel pharmacodynamic studies."

          www.ivis.org/proceedings/wsava/2007/pdf/52_20070401192749_abs.pdf

          "Antiplatlet aggregating therapy may be considered when severe left atrial
          enlargement is present, when spontaneous echo contrast is evident in the LA or
          LAV, or when cats have have had preveious thromboembolic episodes. Aspirin may
          be used, dosed at approximately 80mg every three days. Other agents are presently
          under investigation such as clopidogrel (Plavix). Low molecular weight heparin
          drugs are added when cats have thromboembolic complications. Two particular
          agents, enoxaparin (Lovenox) and dalteparin (Fragmin), have received the most
          attention. Both drugs are expensive but appear to have a far greater safety margin
          than unfractionated heparin. Fragmin (100 U/kg q 12-24hrs SQ) or enoxaparine
          (1mg/kg q 12 hrs SQ) have been used relatively safely. This dose of fragmin,
          however, may be too little- or the frequency too low, to be efficacious. Administration
          rates of every 6 to 8 hours are generally impractical, however, for long term
          administration. Hyperkalemia can occur acutely as a result of re-perfusion injury.
          Continuous ECG monitoring is valuable during the first 3 days of hospitalization.
          Periodic evaluation of BUN and electrolytes are useful."

          Hope this helps.

          Nala
        • taclea
          yes, thank you
          Message 4 of 7 , Mar 5, 2009
            yes, thank you
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