Monday, July 21, 2008

Slentrol ... Weight Loss Drug for Dogs

Update 11/27/2009: No compensation was received for this post. Please see our Disclaimers and Disclosures for details.

Slentrol (dirlotapide) is the “diet pill” for dogs from Pfizer, Inc. It was the first of its kind to be approved by the FDA in January of 2007.

You can read more about Slentrol here. Dirlotapide belongs to a class of drugs that inhibit microsomal triglyceride transfer protein (MTP). The exact mechanism of these MTP inhibitors in weight loss is not fully understood but appears to be from appetite suppression (makes pets feel full and stops them from begging for more food) and decreased fat absorption.

Studies have shown sufficient weight loss results to warrant us keeping Slentrol in our arsenal of weight management strategy. However, it should only be considered after the tried-and-true diet and exercise regimen has failed. A full medical work-up for underlying medical conditions should also be done before reaching for Slentrol.

Side effects reported by the manufacturers and veterinarians who’ve prescribed the drug include:


Soft stool or diarrhea


Poor appetite (although, I would have thought that was the desired effect with this drug?)

Intermittent elevations in liver enzymes

These signs resolve over time or with the discontinuation of the drug.

Studies indicated that approximately 90% of the resulting weight loss was due to enhanced satiety and reduced food intake as opposed to caloric loss due to fat malabsorption. Hence, there seems to be little concern for loss of fat-soluble vitamins as with the lipase inhibitor Orlistat.

Slentrol is intended for intermittent or limited duration use only at this point in time. No long term studies have been done yet. The idea is to use Slentrol as part of the weight management plan. Caregivers learn the normal food portions and dogs learn to stop begging. The effects of Slentrol is gone within days of stopping the drug. Appetite will return and so will the pounds if family members have not learned the lifestyle changes to keep the weight off their dogs.

As with our own weight loss struggles, significant weight (re)gain was noted if caregivers fall off the weight loss plan and return to the pre-Slentrol feeding habits. Without the appetite suppressing effect of Slentrol, the once-fat-but-now-slim dog may easily eat everything that is offered and pack back those pounds.

Your pet’s long-term weight loss success still depends on you and your understanding that, in most cases, you have control over your pet’s diet and exercise. Your dog needs you, not Slentrol, to reach and stay at a healthy weight.

If you still think Slentrol is right for your dog, talk to your family veterinarian. Be prepare with information on the current diet, amount fed, exercise level, etc… to help your family veterinarian assess all weight management options and decide if Slentrol is truly indicated for your dog.


Jordan said...

My dog was prescribed Slentrol after a physical exam but there was no blood work done. After she started the drug she started presenting with all the typical cushings symptoms. Now she is on a cushings drug and her liver values are very high and her thirst and urination have not stopped. It seems to me that my vet and any vet should always do blood work before dosing this stuff out. What do you think?

T-na said...

A full blood panel, including thyroid levels, is generally recommended prior to starting Slentrol. Dogs may be obese due to metabolic and/or endocrine disorders. Pre-Slentrol bloodwork helps rule out medical causes of obesity --- i.e. hypothyroidism ( and hyperadrenocorticism (Cushing’s Disease) ( --- and establishes a baseline to monitor Slentrol's effect on the liver.

Pfizer included this precaution in their insert for Slentrol (
"All dogs should undergo a thorough history and physical examination that includes laboratory tests to screen for underlying conditions. Pre-existing endocrine disease, including hyperadrenalcorticalism (Cushing's disease), should be managed prior to use of SLENTROL."

In your situation, pre-Slentrol blood work would be helpful in determining if your dog had Cushing’s before Slentrol or after. This is important not only for her care but also to evaluate Slentrol for other possible adverse reactions.

I trust you and your veterinarian(s) discussed the diagnostics (including blood test) and treatment options for your dog's weight problem before starting Slentrol. There may have been circumstances with your dog that lead to her starting Slentrol without a recent blood panel. If you don't know the reason, please ask your veterinarian(s). Good communication between clients and veterinarians is important. It is even more critical in managing long-term medical conditions such as Cushing’s Disease.

Treating Cushing’s can be frustrating, especially in the early phase when the maintenance dose is still to be determined. Her liver values and increased thirst and urination will continue until the Cushing’s is controlled (assuming there's no other problems).

Good luck with her treatment.

Unhappy dog owner said...

My dog also had the symptoms for cushings after he was finished with the program and lost all his weight. His liver and adrenalin values were also off the books indicating cushings. Also within a few months of finishing the drug he came down with an advanced type of bone cancer and is in so much pain he has to be put to sleep.

T-na said...

unhappy dog owner,
I am so sorry for your loss. I hope you and your veterinarian(s) were able to figure out what happened.

Were his lab results normal before starting Slentrol?

As you may know, certain types of bone cancer can cause increased ALKP (an enzyme that is often considered a "liver enzyme"). I wonder if that was why it was high a few months before the cancer was diagnosed.

Although we don't use Slentrol, we do hear from other veterinarians who have had good results with it. They do a full work-up to check for underlying medical problems prior to Slentrol. Still with the potential adverse effects, it should remain a last resort drug for weight loss.

Our condolences for your loss. I hope you were able to discuss things with your veterinarian(s). It may not change the outcome, but understanding what may have happened may help provide some closure for you as you deal with your loss.

unhappy dog owner said...

t-na - my vet did NOT do any blood work before putting him on the Slentrol program. Also my vet did not diagnose the cancer. She did two sets of xrays and never saw it until the dog started suffering severe pain and could hardly walk. She said he had hip displaysia and cushings. I took him to another vet for a 2nd opinion and the minute he saw the xrays he was the tumor. He kept him over night to give him an enema and did more xrays in the morning -- which showed that the tumor had more than doubled in the 12 days since the previous xrays were done. There was nothing they could do to save him. He was the best dog we ever had and we still have two chihuahuas. I will never recommend this drug to anyone. We had to put him to sleep yesterday and my family is heartbroken over it. In one month he went from a happy dog to one that screamed in pain any time he was touched and could not get up or down the steps without experiencing intense pain. I will be changing vets now - it's the least I can for my other remaining dogs. I did call the previous vet who did not do the blood test or diagnose the cancer and told her what happened. Monday I am having my other two dogs records transferred to the new vet who did diagnose the cancer. By the way - my dog did NOT have hip displaysia!!!

T-na said...

unhappy dog owner,
It is unfortunate that a full blood panel was not done with the exam prior to Slentrol. Without that information, it is difficult to determine the effect Slentrol had in your dog's cancer and Cushing's. Your tragic story reminds all of us the importance of a thorough medical work-up.

Our sincere sympathy to you and your family for your loss.

Anonymous said...

Our dog has always had healthy thick shiny hair but after being on the slentrol her hair is falling out and she has these small hard areas on her skin. Has anyone had anything similar to this? I can't brush her anymore.

T-na said...

Patchy hairloss as you decribed is not one of the reported side effects of Slentrol.
Was your pet checked for other causes of obesity? Poor hair coat is sometimes seen with hypothyroidism. Also those "small hard areas on her skin" may be skin signs indicative of Cushing's Disease (see links posted earlier), called Calcinosis Cutis. These are raised, hard, almost rock-like areas of calcium deposits which can occur almost anywhere on the body.
In theory, she may not be eating enough (Slentrol makes her feel fuller, eats less) and the lack of nutrition (vitamins, minerals, fatty acids,etc..) lead to poor haircoat. However, that is very unlikely and usually malnutrition does not cause the hard areas you described.

Hence, the hair loss may not be due to Slentrol, but rather due to other underlying problems. Please have her re-evaluated by your family veterinarian.

Anonymous said...

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T-na said...

Is your question on diet and muscle tone for your cat or dog? I was not certain if you were referring to diet and weight loss for pets or people.

If for pets, there are diets formulated to stimulate metabolism and promote fat loss while maintaining lean muscle. A veterinary nutritionist can also work on recipes for your pets if you are interested in the home-prepared meals for them.

As you know, pets, like people, need exercise along with proper nutrition for sustained healthy weight control.

Check with your family veterinarian for recommendations.

jonathan said...

We have a 5lb dog that our vet says should be approx3.5 lbs and place her on Slentrol.She just had the dose increased and now has the runs bad & will not drink at all! This is the 2nd day of this and we stopped the drug a day ago. My question is how long before she returns to her old self? And her poop is like tar?
Worried Mom

T-na said...

jonathan/Worried Mom,
Have you talked to your vet about this change? Stopping Slentrol may help with the diarrhea if that was the cause of it. But I'm concerned about dehydration (from the diarrhea and not drinking). At 5 pounds, she does not have much reserve and can get dehydrated easily. Your family veterinarian can provide supportive care to keep her hydrated until she recovers. Also the tarry stool is concerning. A GI protectant or other medication may be needed. Save a sample for the vet in case testing is needed.

If you have not contacted the vet yet, please do so before she gets worse. Once she recovers, you can discuss other weight control measures.

Hope she gets better soon.

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Anonymous said...

My Skipperkee has been prescribed Slentrol for weight loss. I have yet to administer the first does. Sckipperkee's can not use certain medications (ie: anethetic) for it causes cardiac arrest. Before I use this medication on my boy, I would like to know if the drug trials were conducted on all breeds. And from the other posts I read here, I am even more apprehensive due to the cushings, etc. others have experienced. My vet plans on monthly check ups, has done blood work, etc. but would that catch more serious side effects than vomiting etc. I'm very hessitent to move forward without assurance from Phizer regarding Schkpperkees. I don't like what I see now. Show me how I can see this treatment in a more positive manner and trials that make me feel confortable..

T-na said...

It's great that you are taking an active part in your Schipperke's health care. I wish we can address your concerns but most of your questions are best answered by your family veterinarian. He/She may also have information on Pfizer's drug trials.
As mentioned before, we do not use Slentrol so our experience with it is second-hand from reports by other veterinarians and clients.

If you have doubts about using Slentrol, please discuss your concerns with your veterinarian to see if there are other weight loss alternatives for your Schipperke.

jonathan said...

We have 2 small yorkies and the drug caused bleeding and a number of other side effects!I would not recommend this drug,we now use a simple foods bland chicken & Rice with kible for the vitamins.WE only feed them 2 times a day and a very small amounts.It was rough at first but now they are healthy and happy with about 90% less health issues.Do it through diet not drugs your buddy will thank you :0)

jonathan said...

We have 2 small yorkies that had all kinds of stomach issues with the drug. We took both of them off it and started improving their eating habbits.They now eat 2 times a day with much smaller amounts.We give them bland chicken & rice with a little kible for the vitamins.They both have lost the extra wieght and feel much better!Use diet not drugs you little one will thank you :0)

T-na said...

I am so glad to hear that your Yorkies are doing well with diet and portion control. Definitely agree that proper nutrition, lifestyle and activity level changes should be implemented before reaching for drugs in the weight loss plan.
Congrats on your success!

Kathy said...

I have a 9 year old Weim...she was overweight, weighing in at 153 at her peak, but healthy other than the obesity. The Dr. put her on slentrol about a year ago hoping to get her down to a target weight of 100 lbs. I beleive all the pre-testing was done prior to starting. She lost weight each month and when she got down under 120 lbs, we stopped the slentrol to see if she could lose the balance of weight naturally since she was "over the hump". In the past 2 months, she lost a dramatic 10 lbs and started having occasional seizures which i thought were panic attacks. I took her to the Dr. 2 days ago and the Dr. said all signs point to a neurological matter and more than likely a brain tumor. Without having a catscan done, we have not confirmed her suspisions yet. The next day, she called me to share the results of the blood work. It seems, in addition, her kidneys are failing as well. I am trying to understand how all of this could happen and life can change in a matter of an instant. She looks fine when i look at her...she eats, pees, poops, drink, goes outside...nothing has changed. We have no idea what to expect going forward....obviously, my heart is broken. Has anyone else had any comparable issues after using Slentrol? there doesn't seem to be an issue with her liver at this point...but slentrol is the only thing she has taken....please share any info with me...


T-na said...

I am so sorry to learn of your Weim's illness. How soon after you stopped Slentrol did she starts having seizures? How long was she on Slentrol? As noted earlier, we do not use Slentrol so have no presonal experience with it. I have not seen any report directly linking Slentrol to seizures or brain tumors, though.

It does not make it any easier to deal with her illness but it is possible this is all unrelated to Slentrol. If she has neurological disease, the blood test that was done prior to the Slentrol would not have picked it up.

The kidney disease is different though. Your doctor should be able to compare the values to the pre-Slentrol and also to those taken during the time she was on Slentrol (I assume she was tested to make sure she did not have problems with Slentrol?). Slentrol was reported to affect the liver values, not the kidneys though.

I hope this response still find your Weim in stable health. Perhaps your doctor was able to control the seizures and manage her kidney disease?

Anonymous said...

We had a dog that used slentrol. Yes he lost weight but then developed bladder cancer. I will never use this drug again since I believe it was partly the cause of the cancer.