Low Dose Naltrexone For Dogs

I had to figure out a Low Dose Naltrexone dose for a dog not too long ago.

A quick look at the doses people said their Vets were prescribing was a bit confusing, as the doses being prescribed were equal to – or bigger than – what is recommended for people. But… people were reporting succcesses with those doses.

After checking out the data that I could find in the literature for the blood levels and metabolism of naltrexone in dogs and people, I think I understand why those doses work.

Dogs’ livers break down naltrexone MUCH faster than peoples’ livers. So, it takes a bigger dose than you would think necessary to get blood levels that are equivalent to what you have when people take the doses that are recommended for them.

In fact, dogs’ livers chew up naltrexone so fast that it probably becomes impossible to maintain adequate blood level profiles in dogs much bigger than a cocker spaniel with a single dose.

The theoretically based graph pasted below illustrates this effect.

The Series 1 line is the blood concentration for a ‘normal’ sized person plotted against hours on the x-axis…

The lines for Series 2, 3, and 4 are blood concentration levels for increasing doses of naltrexone in a cocker spaniel sized dog.

Notice that the blood concentration level curves fall below the human profile curve for all doses somewhere between 3 and 4 hours after administration.

Basically, what this graph shows is that dogs’ livers deactivate naltrexone so quickly that you just can’t get a reasonable Low Dose Naltrexone dose that will give a human-like plasma level curve in dogs larger than a cocker spaniel.

So, what can we do?

If I had a large dog I would dose them with a normal ‘human’ dose two times every evening, with the second dose being given around two and a half hours after the first. If possible, dose titration to effect would be desirable. (in other words, you might have to increase your doses in some predictable manner if the original doses don’t work)

But, you often don’t have time to do this kind of work. In those cases you’ll just have to dose as described and hope the dose is ok.

Too big a dose and it won’t work. Too small and it won’t work either. Keep this concept in mind. If you increase your doses and don’t see an effect think about your doses for a second. They might be too big.

Print this posting out and take it to your Vet. He will understand what I am talking about.


NTX Single doses

Hope this helps.

Again, remember… I am not a physician. Just a pharmacist telling you what the literature shows. Always seek professional advice from your physician, care giver, or veteranarian… as applicable…




8 thoughts on “Low Dose Naltrexone For Dogs

  1. Hi, great info on naltextrone para canines, my dog is dying…. I have a question:
    As a pharmacist, would you consider taking ldn
    simply as a quality of life nutrient (supplement) for yourself -(well aged in my case)
    while doing research on yr (dawg??
    I AM!
    WHY NOT?
    wes the mad (cientist..

  2. It is hard for me to understand all of this chemistry stuff, but I do have a cocker spaniel and she is 21.6 lbs. and is on .05 mils LDN every am for her non contagious mange. I will keep her on it for life for her since D…. mange is auto immune. Even though the mites are gone. My last Cocker had live cancer and disease and a bum leg she lived a yr and half long then expected and gained full use of her back leg. My vets was stunned. I was Grateful!

    1. Our dog weighs 52lbs. She is an Aussie with non-contagious mange as well. What dose would you recommend for her? Does this control your dog’s itching and self harm? Our dog has regained her hair and is improving but she still digs and bites herself and causes bleeding on a daily basis, she has been suffering with this for nearly 6 years and we have spent thousands on vet visits and treatments, natural and conventional. I am thinking of starting her on ldn. Please advise?

  3. Thank you for posting this; your effort is very much appreciated. Our dog has IBD, and we will be looking into using this medication to help treat it; it seems very promising.

  4. My 10 year old Samoyed is very ill at the vets at the moment…2nd day on drips to rehydrate him, his kidneys not functioning says vet.
    Would you know if LDN would be beneficial…that’s if my dog will take it and the vet administer it?

  5. I have a 3.5lb Chihuahua who was diagnosed with Sards 2 weeks ago…would LDN help her…and what Vet in Philadelphia area would prescribe it.

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