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…




12 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?

      1. I have one BT rescue who has suffered with skin and yeast disorders since we got her. Nzymes and Dermagic have made a HUGE Difference for her!

  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.

  6. Thank you, this is great info. I brought your findings to the attention of our vet as LDN was recently prescribed (at my request) for our 52 lb dog to treat an auto immune condition. Our vet (an internal medicine specialist) said that 3mg daily is all she is comfortable prescribing. (Our case is the first time she has used this drug). So I am hoping you might be able to refer me to one of the veterinarians you mentioned who have prescribed larger doses as maybe s/he has more hands-on experience with LDN and could provide us a 2nd opinion. Perhaps you could email me the info? Thank you!

  7. Thank you for the info. I know LDN has placed my husband’s Crohn’s practically in remission, and so I’m hoping you can advise us about our 120 pound Great Pryenees dog. She has been diagnosed with encephalitis (although blood tests don’t indicate infectious encephalitis). She shows most of the symptoms, and she is a very weak and disoriented girl right now. Breaks my heart! She’s on prednisone to reduce inflammation, but will be titrating down later this week. My experience is to start low and increase the dose. I’m thinking Angel, considering what you wrote about dog livers, should start at 4.5 mg once daily to see if this makes a difference. We could increase the dose if need be, but I’d like your opinion. She could have auto-immune encephalitis, but the vets where we live have never heard of LDN. Thanks for any guidance you can give, Cathy

  8. My 11 yr. Lab..MATILDA..has HEMANGIOSARCOMA. ..we are in shock..diagnosed Oct 2nd. Immediately started her on LDN…ACTIGAL .RED PALM SEED OIL..LACTILOSE SYRUP..RICE..LIVER. CHICKEN..AND LOTS OF LOVE. ..Vet. didnt think she would live thru surg. Praise GOD SHE IS STILL LIVING LOUD! Removed 3 gallons of blood from abdomen and found bleed. Was able to stop with VIT. K..and surgical paste. ..had abdominal tap last Monday 30th.to remove fluid build up..1 gal. NO BLOOD….Thats the only problem is abdomen responding to tumor around intestine. Lab values unremarkable. My question..We have her on LDN 2CC’S at bedtime…her weight is 64.5 lbs. .no new tumors…no bleeding…the abdominal tumor did grow some. .what would be your advise on dosage. She eats, runs, plays, LICKS AND LOVES….i saw too info on Budwig Protocol and Artemisinin-Wormwood? Gradford Stokes

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