Revolution for Rabbits

Question
QUESTION: I noticed that my big French Lop was shedding and when I was combing her fur, I found white flakes some attached to the bottom of the loose fur.  Upon further examination, I realized that it wasn't just normal shedding of the undercoat, but that she appeared to have mites.  I searched on the internet and found that Revolution was recomended.  The new vet at my animal hospital had recently suggested I might try Revolution for my cats that had ear mites.  They don't carry Revolution, but he could write a prescription for me.  I treated them with the same stuff as before but now I thought it would be a good idea to try.  I called my vet with news of the rabbit and requested a prescription.  I have 10 rabbits and 7 cats and I told him that I had read that the cat and dog Revolution were the same product and if so, could he write me a prescription for the large dog size so I could cut my costs down.  He did.  I bought 7 doses from another local vet that carried the product.  My vet gave me instructions to give both the cats and rabbits that were between 5 & 15 pound, .75 ml.  But when I read the information on the package, it has a chart and it shows that the cat and dog formulas have different potencys.  The cat product has a potency of 60 mg per ml while the dog product has a potency of 120 mg per ml.  Does this mean that if I follow my vets instructions, and give them .75 ml, since I am using the dog product, that I am giving them a dosage with twice as much potency as I should?  Is the simple answer to cut the dosage in half to 37.5 ml?  

I know I should call my vet to get this clarified but I am concerned that maybe he might not understand what I am trying to say and that he might just say it is okay thinking that he looked up the amounts for the cat dosage.

thank you.

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UPDATED INFORMATION ON REVOLUTION FOR RABBITS (JANUARY 2009):

Revolution (selamectin) comes in two concentrations:  120mg/ml and
60mg/ml.  The former is sold in tubes for larger dogs, and the latter is
sold in tubes for smaller dogs, cats, puppies, and kittens.  If you're not
sure which solution you have, check the box.  The concentration is listed
there, usually in very fine print.

Either solution will work for rabbits.  It's the amount that must be
modified to give the correct dose, which is 6mg/kg.

Note that a cubic centimeter (cc) is the same as a milliliter (ml). If you
are using the more concentrated solution (120mg/ml), then use a
*needle-less* 1cc syringe (from your vet) to draw up 0.05cc per kg of
rabbit.  For example, a 4kg rabbit would get 0.2ml of the 120mg/ml
solution.

If you are using the less concentrated solution (60mg/ml), then use the
1cc syringe to draw up 0.1cc per kg of rabbit.  The same 4kg rabbit as
above would get 0.4ml of the less concentrated solution.  Obviously, you
need an accurate weight for your rabbit to determine the correct volume
of Revolution.  (Note also that 1kg = 2.2lb)

Squirt the Revolution onto the skin (part the fur, and gently press the
tip of the (NO NEEDLE!) syringe to the skin) on the back of the neck area,
just above the shoulders.  This dose should last 2-4 weeks, but you should
always consult your veterinarian about proper dosing, and not use any
medications on your rabbit without first consulting your vet.

You can find a rabbit vet here:

http://www.rabbit.org/vets

who can help you.

Dana

ANSWER: Dear Michele,

Wow, that's news to me!  I've been told by various vets that all the Revolution solutions are the same concentrations!

In any case, we use the dog formula, and for a rabbit of about 4-8 lbs, we apply 6-8 drops on the back of the neck.  It works very well, and we've had no adverse reactions.

The only contraindication would be if a rabbit has any sign of head trauma or other problem (e.g., head tilt) that might indicate inflammation in the brain and hence, a compromise of the blood/brain barrier.  But a healthy rabbit should have no problem with the Revolution.

Hope that helps.

Dana

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

QUESTION: Thank you for your reply.  What would you recommend for my French Lop that weighs 13.5 pounds.  I did call Pfizer and of course they recommended against using the product other than how it is meant to be used as packaged.  I understand their stand on that but at the same time with 10 rabbits, 7 cats and also 3 large dogs, I need to keep my costs down.  

On the Pfizer website I found this bit of information:  The recommended minimum dose is 2.7 mg selamectin per pound (6 mg/kg) of body weight.  So if I try to do the math, 2.7 times 13.5 (rabbits weight) = 36.45.  So I take it that my rabbit needs 36.45 mg of selamectin.  Then when I look at the information for the 85.1 - 130 lb Revolution for dogs, I find that each vial is 3 ml and each ml contains 120mg of selamectin for a total of 360 mg of selamectin.  For my French Lop I would need 36.45 mg of selamectin out of the total of 360 mg of selamectin in one vial which would be 10.125 % of the total selamectin in this size vial.  Since this vial contains 3 ml of product and I need 10.125% of that, I would need to use .30375 ml or rounded off to .3 ml.  Does that sound right?  

If so, then for an 8 pound rabbit, I come up with .18 ml of the large dog vial.  2.7 times 8.0 (rabbits weight) = 21.6 mg of selamectin for an 8 pound rabbit.  I would need 21.6 mg of selamectin out of the total of 360 mg of selamectin in one vial which would be 6.0 %.  Again, since this vial contains 3 ml of product and I need 6.0% of that, I would need to use .18 ml or rounded off to .2 ml for an 8 pound rabbit.

I appreciate your help.  If you could let me know how many drops you would sugget for the 13.5 lb French Lop I would appreciate it.  Also if you could let me know if you think I have a sound understanding of how to take what Pfizer is recommending as dosage and using the correct math / formula to come up with actual dosag

Answer

Dear Michele,

Wow, good math!  :)

A volume of 0.2ml for an 8lb. rabbit sounds about right.  When we treat our big Vash (14 lbs. of manatee-faced love), we use about 9-10 drops on the back of the neck, and that does the trick quite well.  

Pfizer will not recommend use of their product on any species other than what they have officially and legally paid for (it can cost millions of $$ to get a drug approved for any given species), since they must engage in legal c.y.a.  However, almost every experienced rabbit vet I know uses this product "off label" on rabbits with excellent results.

In fact, almost every drug used on rabbits is used "off label" since there are almost no drugs on the market approved for use in companion rabbits.  It's just the way the drug companies do business--and the vets.

Hope that helps.

Dana