Slentrol Part II

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slentrol-adverse-reactionThe more you think about it, the worse it gets.

I recently wrote a brief post about Slentrol, the dog obesity drug.  You can read that here.

For those who are using or considering using Slentrol,  let’s take a closer look at how it works.

The official Slentrol website explains how the drug works as follows (italics are mine):

SLENTROL is a medicine called an MTP inhibitor. It works by preventing some of the fat your dog eats from being absorbed into the body. When that happens a message is sent to your dog’s brain that tells him he’s full. In fact, one of the first things you’ll notice is that your dog won’t want to eat as much as before. The weight loss happens because your dog is eating less food.

OK, sounds pretty straight forward.  If you were reading this description about a drug for humans, it might actually make some sense–> people who can’t control their appetite could possibly lose some weight if their appetites were reduced and therefore they didn’t go back for second (or third) helpings etc. (Note- I am in no way condoning the use of drugs as an acceptable weight loss protocol! Rather, I am giving Pfizer the benefit of the doubt from a ‘logic’ perspective.)

However, does this protocol even make any sense for a dog?  The answer is  a resounding NO.  Unlike humans, dogs do not have free and unlimited access to their food supply!  At least not the dogs that I know.  They do not control how much or what they eat– they don’t need to have an appetite suppressant to keep them out of the fridge because they don’t have access to the fridge to being with.

 Yes But….

Yes, but giving my dog a pill is easier than restricting their diet… I imagine that this might be one argument for using Slentrol.  But is it really easier?  What is the cost of employing this strategy?  First let’s look at the health costs.  Again, quoting from the official Slentrol website, here is a snippet of the information on the side effects of the drug:


WARNINGS: Not for use in humans. Keep this and all drugs out of reach of children. Adverse reactions associated with humans ingesting dirlotapide include: abdominal distention, abdominal pain, diarrhea, flatulence,headache, increased serum transaminases, nausea, and vomiting.

The safety of SLENTROL use in dogs has not been evaluated beyond 1 year.


The adverse reactions associated with treatment with SLENTROL include vomiting, loose stools/diarrhea, lethargy, and anorexia. These adverse reactions were mainly observed during the first month of treatment or during the week after a dose increase. Vomiting was usually mild in severity, of short duration, and resolved with continued SLENTROL treatment. The SLENTROL-treated dogs generally had an increased frequency and duration of vomiting and diarrhea compared to the control dogs. The control dogs received corn oil.


You will notice that the control group dogs received corn oil and this opens up the possibility that at least some of the adverse reactions from the control group may have been overstated (and thus, the Slentrol group looks better).  Tabling this question for now, the data still show that the Slentrol group experienced a greater incidence of side effects.  The top 3 side effects, vomiting, diarrhea and lethargy were 14%, 82% and 176% respectively more likely  in the Slentrol group.


It seems like a no-brainer to me.  Don’t use a drug to manage your dog’s appetite and weight.  The best way to manage your dog’s weight is to exercise them more, learn exactly how many calories they should be fed based on their activity level to achieve their target weight (and use a measuring cup so that you know you are feeding the correct amount) and stick with the program.  It will work, you will save money on drug costs, and you won’t have to worry about the side effects.




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  1. I have to agree. In addition to using Slenterol, it seems that a pet parent would still have to modify the amount of food, exercise their dog, etc…so why not just do those things without giving a drug? Here’s a tip we use: if your dog seems to act hungry, pestering you for snacks, you can offer something healthy like baby carrots to fill them up. Or, sometimes when my dogs get like this, I take them outside to play and this seems to distract them.

    • Yes, it is really as simple as you suggest Peggy. Our dogs love carrots also! Thanks for the helpful tips.

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