Meloxicam (Metacam) - higher dosage now standard?

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mmeadow
Supporter 2004-2020

Post   » Mon Oct 19, 2015 11:50 am


I had questioned my vet's prescription of meloxicam (Metacam), which seemed 10 times higher than our usual guidelines. With his permission, I'm pasting in his response. He said he would respond to any further questions, so I will gather comments here and forward if appropriate.

From the vet:
The main studies in the past few years are in rabbits, but drugs studied in Guinea Pigs and rabbits previously show very similar uptake with oral administration, which makes sense since the digestive tracts are so similar. A dose for a dog is 0.1-0.2 mg per kg of body weight, which is what was used to base the 0.07 mL dose previously used for your Guinea Pig. Since 2012, formularies for Guinea Pigs have stated the need for greater than 0.5 mg/kg for rodents, with does as high as 1-2 mg/kg for rats and mice. These were based on work with laboratory animals.

In rabbits, two studies done in 2009 showed that the dog dose was ineffective and a dose of 1 mg/kg minimum was needed to achieve behavioral evidence of pain control in rabbits:
  • Behavioral Effects of Ovariohystorectomy and Oral Administration of Meloxicam in Laboratory Housed Rabbits. Research in Veterinary Science; 2009, March

    Single and Multi-dose Pharmicokinetics of Meloxicam After Oral Administration to the Rabbit. Journal of Zoo and Wildlife Medicine; 2009, December
The higher doses were evaluated and safety tested over the past 2 years:
  • Pharmicokinetics of Meloxicam in Rabbits After Oral Administration of Single and Multiple Doses. American Journal of Veterinary Research; 2013, April

    Pharmikokinetics of Meloxicam Administered Orally to Rabbits for 29 Days. American Journal of Veterinary Research; 2014, February
I’ll also tell you that since using 1 mg/kg doses in both rabbits and Guinea Pigs I have noticed (as have exotic animal practitioners across the country) better recover from illness, injury and surgery in both species and no health concerns from these doses in practice has been observed.

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mmeadow
Supporter 2004-2020

Post   » Mon Oct 19, 2015 11:56 am


I asked him why we'd observed apparent improvement on the tiny doses we had been giving our pets. I wondered whether there was a slope in response? ie could there be some pain relief at even a minimal dose, improving slightly at greater amounts? He disagreed, suggesting that it was observation bias: we saw what we expected to see. Very interesting! However, sad to think of all the animals receiving ineffective analgesia--and of the animals in the experiments that produced this new data.

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Lynx
RESIST

Post   » Mon Oct 19, 2015 12:36 pm


Sounds like the recommendations on this site should be updated (I think they're fairly old - at the time they were put up, there actually was no firm guideline for meloxicam).

I'll wait a bit until we have more feedback from other members.

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Jessie
Supporter in '13

Post   » Mon Oct 19, 2015 1:56 pm


We currently give dog metacam twice a day. The amount varies from pig to pig. Snowy has had 0.25cc at 700g weight, for major dental abscess. Buzz has an incisor problem with cystits and was on 0.2cc at 840g.

I'm really sorry but I can't do the workings at the moment. I'm not long in off the road and my brain is frazzled.

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mmeadow
Supporter 2004-2020

Post   » Mon Oct 19, 2015 3:01 pm


Thanks, Jessie, I understand the frazzled brain problem! However, if you can post the concentration (how many mg of medication per ml) that would be helpful.

Meloxicam seems to come at 1.5 mg/ml or 0.5 mg/ml.

Metacam for dogs info sheet

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Jessie
Supporter in '13

Post   » Tue Oct 20, 2015 7:32 am


It's the 1.5mg/ml metacam.

We've got a check up in a few weeks time. I'll see what our vet says. I know he has a reason for using higher/more frequent doses than what has been our "norm" from other vets in the past.

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mmeadow
Supporter 2004-2020

Post   » Tue Oct 20, 2015 10:35 am


Very curious to hear what your vet says. Maybe you could show my references.

I ought to mention to my vet that just a year ago another vet in his practice was still dosing at the old levels.

Talishan
You can quote me

Post   » Tue Oct 20, 2015 3:53 pm


Mm. I disagree with the observation bias, and also am not completely comfortable with the direct extrapolation from rabbits. The species are very similar in many ways but not in all.

That said: 1) I've used higher doses than our GL recommendations several times, to good effect and with no apparent harm, and 2) there are other medications (doxy being the main one I'm familiar with) where a higher established rat/mouse dose is effective in guinea pigs as well to no ill effect (and is preferred to extrapolation from other, seemingly more similar species).

Many vets (still) severely underdose meloxicam. If nothing else, these new standards will help pigs get the analgesia they need when they need it.

slavetofuzzy
4 the Good of all Pigs

Post   » Tue Oct 20, 2015 6:41 pm


My vet (and Talishan's) dose on the low side. BUT, for one of my pigs she has recently dosed .2 twice a day. I raised an eyebrow, because she usually doesn't dose that high! She assured me that she tends to go low, but in this case it would be completely warranted for the higher and more frequent dose. I use the one with the purple ribbon, or band on the box (not yellow). I don't have it in front of me to know the strength. The pig in question weighs in the 800 g range.

Talishan
You can quote me

Post   » Thu Oct 22, 2015 1:49 pm


I am pretty sure purple (box is a pale purple?) is the 1.5 mg/mL. 0.5 appears to be a darker purple box with a yellow band.

I think Dr. A. has pretty much given up with me. She knows I'm gonna give them what I'm gonna give them, so she just prescribes it. ;-)

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Sef
Supporter in 2019

Post   » Sun Oct 25, 2015 12:21 pm


It's interesting, but I think I agree with the one abstract which stated, "A dose of 1 mg/kg may be necessary to achieve clinically effective circulating concentrations of meloxicam in rabbits, although further studies are needed." It may very well be true that higher doses are safe and are indicated in certain situations, but I'd feel better if there were more data on this -- particularly where guinea pigs are concerned. As already said, metabolism in rabbits and guinea pigs are certainly very similar but not identical.

Something I think owners also need to be aware of, is that NSAIDs are contraindicated in patients with either liver or kidney dysfunction, and in patients where dehydration is an issue. Both of those situations are not uncommon in guinea pigs with bladder stones and other illness, and I think extra care in dosing Metacam is especially warranted there.

It will be interesting, though, to see what some of the new formularies recommend as more data is available. I think I read the latest edition of the Carpenter is due out sometime in early 2016-?

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