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Old February 10th, 2009, 09:18 PM
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Dr Lee Dr Lee is offline
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Originally Posted by Bh1980 View Post
Our 18month old 10 pound min pin was just diagnosed with Demodex... Our instructions from the vet were to start her out on 1/10 cc everyday for the first week. During the 2nd week, we are to give her 2/10 cc everyday. During the 3rd week, we are to give her 3/10 cc everyday and continue until the medication is finished. Does this dosage sound too high during the 2nd and 3rd week? The vet also didn't say how long to continue the treatment. He just said to come back in May. Also, is there any kind of topical ointment that we can put on the spots with hair loss during the ivermectin treatment? Possibly Goodwinol ointment? ...
Good questions. I am sorry that you did not get your information answered at the office. Hopefully I can help.

Let me start with the dosing question first.

Dosing according to Plumb's Drug Handbook:
Typical dose is 400-600 mcg/kg by mouth every 24 hours.
10lbs is 4.55 kg. Thus the daily dose is 1820 to 2730 mcg.
Typical ivermectin is 10,000mcg/ml
Thus the typical dose is 0.18 to 0.27 cc by mouth every 24 hours.
Some doses can go higher so I don't have a problem with 0.3 cc by mouth every 24 hours.

Your vet is actually being very conservative with the increasing of dosing. I would typically have you start low (subtherapeutic) and increase daily, not weekly until I got you to the actual treatment dose and then maintain until clinical signs resolve. I usually start at 1/4 or 1/5 of the dose and increase to a maintenance dose at day four or five.

So I think you vet is doing just fine. I might have stopped at 0.2 or 0.25 depending upon the case but I think 0.3 is just fine. Again: I am basing this of information of a healthy 10 pound non-ivermectin sensitive pet with a confirmed dose of demodex with a typical oral ivermectin medication.

Why the scare about ivermectin? There are some pets that cannot deal with ivermectin. If they cannot, a standard dose can lead to severe neurologic signs such as blindness, disorientation, coma and death. While we think of working breeds or dogs with "white feet, don't treat" as the only dogs not being able to handle ivermectin - any dog can have this problem. It has been identified as a mutation in the MDR1 (Mult Drug Resistance) gene. Washington State University does testing for $70. Owners can obtain a test, perform an oral swab and get results fairly quickly. Here is the website: MDR Testing Information.

Why step up incrementally? For dogs that are not suspected of having a problem with ivermectin, this is a relatively safe and effective way of 'testing' your pet. If they have a problem with ivermectin, then they will show clinical signs at the lower dose. The 0.1cc dose is not enough to treat demodex in a 10 lb dog but enough to typically show clinical signs if they are sensitive. If we started at a dose that would treat the demodex at 0.3cc and the pet had ivermectin problems - we would be a dose that could lead to serious life threatening problems.

How long to treat? Textbook is to perform weekly skin scrapings and continue treatment until there have been two negative scrapings. This is often very expensive for owners. It is common to continue until clinical signs have resolved and possible scrape at that time. Typical treatment courses will last 2 to 4 months.

Goodwinol Ointment? For single local spots of demodex, goodwinol is my treatment of choice. If we see generalized demodex (more than one spot), then ivermectin is currently the 'treatment of choice'. Goodwinol ointment at the same time will not necessarily increase response time.

Additional ointments or supplements? I do recommend Omega 3 fatty acids (fish oils) for demodex cases. (alright, I admit, I think I recommend this for many, many pets... ) I also think conditioning sprays, creams and shampoos can help with dryness.

Final note: Thanks hazelpackrun for the tip on this thread.

I hope this helps.
Christopher A. Lee, D.V.M., C.V.L.S.
Promoting surgical options and pet comfort through the use of lasers.
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