High Metacam dosage, advice please

Question
QUESTION: Hi Dana,

To re-cap a bit, my two bunnies, 9 & 10, whom have been having slow recoveries from dentals and troubles eating have had a new condition diagnosed after x-rays have been re-taken.  A new vet explained to me, that changes to the roots of their teeth makes it painful for them to eat and says it will need to be controlled with pain meds.  This applies to both my 9 and 10 yr old, but my 10 yr old Pepsi, also has an infection in her upper mouth, she has been given marbocyl antibiotic for this.

My concern is that this new vet has given a very high dosage, for both rabbits for the first 10 days, he has prescribed my 9yr old Opal - 0.80ml twice a day, she weighs 1.27kg, for Pepsi - 1 ml - twice a day, she weighs 1.5kg.  This is definitely the correct dosage.  I've asked another couple of people and they think its quite high considering their weights.  Also, am concerned about their kidneys and any affects on the stomach.  I did ask my vet about the use of an antacid for protection (as I think you have mentioned famotidine previously to me) but he's not heard of this and doesn't seem to think it would help.  Is there anything I can to say to him to show it may help, can you explain to me how an antacid would help with protection so I can tell him?

Also, I did enquire as to whether their teeth would line up okay as they have had one molar tooth out each now, but he did not think that would affect the alignment.  I am a bit puzzled as to what causes their spurs to occur if the teeth do line up though, please could you shed any light on this?

Am most concerned though about the metacam dosage and if it may harm them in any way to give the above amounts, would appreciate if you can get back to me as soon as you can.

Many thanks


Sue

ANSWER: Dear Sue,

If you can tell me the concentration of your metacam suspension (it's usually 1.5mg/ml), then I'll be better able to help you.  But the standard dose our vets use for rabbits is 0.1 - 0.3 mg/kg once every 24 hours.  If the suspension you're using is the 1.5mg/ml we have, then the dose your vet has prescribed is about 4x higher than anything we ever use.
Same for Pepsi's dose.

I think I might try to find another rabbit vet for a second opinion about this:

www.rabbit.org/vets

Metacam is *supposedly* a selective cyclooxygenase inhibitor (a.k.a. Cox-2 inhibitor), but this is arguable, according to some of the more recent data.  And your concerns about their kidneys are valid, especially considering their ages.

You might ask about tramadol for pain (we use 2-6mg/kg BID), a synthetic opioid that has turned out to be *fantastic* for things like joint and tooth pain.  No fears of GI troubles with that one.  (Just don't let your little ones become addicts.  ;)  )

If your vet truly doesn't know what famotidine is, nor why stomach acid and ulcers are a concern with NSAIDS, then I would *definitely* try to find another, more rabbit savvy vet for a second opinion.  The above is just very basic medicine that any vet should know.

Molar spurs can grow even if the molars are not misaligned if the bunny isn't eating foods that promote a side-to-side chewing motion, which keeps spurs from forming.  Bunnies fed primarily pellets chew up and down, crushing the pellets, but may not get enough sideways grinding motion without other foods, such as fresh grass, twigs, and fresh grass hay.

Hope that helps!

Dana




---------- FOLLOW-UP ----------

QUESTION: Hi Dana,

Thanks for the info about the dosages for metacam.  The suspension I'm using for my rabbits is the 1.5mg/ml so it is the same as the one you use.

I have seen my vet again for a post dental check up with my rabbits and as there has been some improvement with their eating, he has dropped their metacam dosages by half, so Pepsi (1.5kg) is now getting 0.5ml twice a day and Opal (1.27kg) 0.4ml, but he did say if they show any decrease appetite to up the dosage again.  I realise this is still higher than what you would use, hence my writing back to you for further opinion.

I think this vet has prescribed such high dosages to try and knock out the pain that was preventing my rabbits eating normally (they were eating really soft food and not really enough for a lot of the time) due to this condition of painful tooth roots which has just been diagnosed by him.  I think if they continued to improve he may lower dosage again.

Having read your reply though I was still feeling anxious about the dosages and longterm possiblity of keeping my bunnies on metacam so asked him again about any dangers from ulcers and possible kidney concerns.  He says rabbits don't suffer the same side affects as humans and require higher dosages due to their own body chemistry.  He uses high dosages a lot of the  time and says does not see any problems regarding ulcers or kidneys.  He also says rabbits stomachs are never empty.  I do worry that in the case of my rabbits though (as I don't regard them to be eating normal rabbit intake at the moment and they haven't for some time) so I'm not sure that would apply. Can you comment on that remark?

As he doesn't see stomach ulcers it is pointless me asking about protection from antacids.  Do you know of any cases where metacam has caused ulcers, or kidney problems, does it happen regularly??  I do feel a little confused by differing opinions on this, I do prefer to err on the side of caution if there are any doubts, but this vet (who claims to have lots of experience with this) says he doesn't see problems.

I do value your opinion very much so hope you will be able to get back to me once more on this,

Thanks again,


Susan

Answer
Dear Sue,

Quoting your vet:   "He says rabbits don't suffer the same side affects as humans and require higher dosages due to their own body chemistry."

That may be true.  But he does not KNOW what side effects rabbits might suffer.  And although he says he's been using a high dose for a long time without seeing problems, this is not the same as a controlled study.  I'm glad he's not seeing problems.  But that doesn't mean they don't happen.

It's true that a rabbit's stomach is never empty, and this does help mitigate any excess acid that an NSAID might cause.  But we don't know just how effective that is, either, or if there could be problems with anorectic rabbits.  

I don't know of any cases of confirmed metacam-caused ulcers or renal problems, so it's probably not common.  But it *is* stated by those who have done research on these drugs as a potential problem, and most vets are aware of this.  Your vet seems to be erring on the side of not-so-much caution.  

I don't know.  It seems odd to start at a high dose of pain meds, and then back off.  It might seem to be more useful to start with the lowest possible dose and see if it needs to be increased, instead.  But that's just my opinion.

Hope that helps.

Dana