Prozac and Your Dog

Prozac for Aggression

Q: Dear Dr. Mike, I have bookmarked this website; your answers are very honest and informed.

I am writing to ask for information about giving Prozac to dogs. I have a 5 yr old male neutered mastiff who is sweet at home with family & friends but unreliable with strangers (dogs and humans). He cannot be walked on the street because he lunges at strangers unpredictably. Due to his huge size, even if I control him, a small lunge looks very threatening to people. Also he might knock over anyone who happened to be carrying or playing with a soccer ball or football (he is extremely ball possessive).

Professional trainers have diagnosed him as having fear or possessive aggression. Also they say he has the intense persistence of the type so valuable in drug seeking or bomb seeking dogs but not so valuable in a pet. I have put extensive effort since his puppyhood into professional training and socialization, and I have experience with obedience competition (in my other dogs). All to no avail. I also have tried different techniques for correction and control, dietary changes, and have had him checked out for physical problems. Crom does have some arthritis but has been made fairly comfortable with Bufferin, and this seems to make him less grouchy (but not more reliable). I am committed to keeping my dog into old age, but I'm concerned that he could be dangerous. Also it isn't fun for him never to go on walks.

I read about Prozac used on dogs in the AKC Gazette but there was no reference to the research studies (on using Prozac for aggression). I have have not been able to find references to these studies on the web. What do you know of this literature? The veterinarians I have consulted about Crom never suggested Prozac or other medication. I would like your opinion and reference to the studies so I can read them for myself. Can you help? Thanks very much!

A: If anyone has published studies on the use of fluoxetine, (Prozac Rx) for aggression in dogs, I am not aware of them. I have corresponded with Dr. Ilana Reisner, a board certified veterinary behaviorist, about the use of these medications. She has been trying them in some cases of aggression and feels that they can be useful.

There are several behavioral modification medications used to treat aggression in dogs. Prozac is one. If I understand the references to it correctly, this has been used mostly to treat dominance aggression. Lithium carbonate is also used for dominance aggression by behaviorists, for some cases. This sort of aggression is usually directed at family members and can occur quite suddenly. Since that isn't the problem you are having, there may be other approaches that might help more. However, I am not a behaviorist and can not claim to be up to date on the latest treatments. So it is also possible that these medications are being used for other forms of aggression and may be useful.

For fear based and sometimes for territorial type aggressive behavior, the preferred medications seem to be anti-anxiety drugs. Among these would be diazepam (Valium Rx) and amitriptylline (Elavil Rx). These medications can reduce anxiety and make a dog a little less likely to respond aggressively to frightening or stressful situations. We have tried amitriptylline for several cases of aggression and feel that it has been helpful in one or two cases only. Most of the time, some sort of behavioral modification is necessary as well.

A good physical exam and general lab profile to rule out underlying problems is always a good idea when assessing aggression. The next best step is consultation with a veterinary or certified animal behaviorist, if possible. In many places, these people are not easily available for consultation, though. A really knowledgeable trainer can be a great help but it is extraordinarily difficult to evaluate trainer's abilities. Assuming there is not a physical cause and that you have exhausted behavioral modification techniques, you are left with muzzling Crom when walking him, which won't help with the lunging but might make people less nervous about him; use of a Promise or halter collar to give yourself more control (this worked very well for our Rottweiler who liked to lunge at people); and finally, medical therapy.

Your vet may be able to at least consult with a veterinary behaviorist. This has helped us on a couple of occasions when the owner simply couldn't make the trip to the behaviorist.

Mike Richards, DVM

Assessing valid scientific study

Info on Prozac

On the page that discusses Prozac, Dr. Mike says he's not familiar with any studies done...I'm surprized he's not aware that most if not all medications that deal with brain chemistry are first tested on dogs before given to humans. Secondly, I can't believe he hasn't heard of Tuffs University?? They're focus is on behavioral drugs for dogs...Prozac, in particular, is one of THE most tested. I believe there have actually been thousands of tests, world wide, on the use of Prozac and dogs.

If you're interested in more info on Tuffs Univ. Let me know and I'll get the number for you from my vet...I have consulted with them in the past and was very impressed.

Thanks! Katie

A: Katie-

I think that there is some confusion about what I mean by a valid scientific study and what many people perceive to be a valid scientific study. There is also a problem with our website, in that we did not start dating the postings until this year. It makes it hard to evaluate which information is newer on the site. There were two studies published in the fall of '98 on the use of fluoxetine (Prozac Rx) in dogs that are valid controlled studies.

While it may be true that many medications that are intended for use in people are tested in dogs I don't think that anything close to the majority of testing is done in dogs. At the PubMed site, with the National Institute of Health's medical journal database online, there are only 9 references found on a search using "fluoxetine and canine". Of these nine references, only two deal specifically with disorders likely to be treated by veterinarians in practice and one of these studies only involved nine dogs. The other study involved 42 dogs.

Clinical trials are most reliable when a medication is compared against a placebo and neither the patient nor the practitioner know which is being used in any particular patient. These studies are known as "double blind" studies. It is reasonable in some cases to do "single blind" studies, in which the practitioner knows whether the medication is a placebo or the real thing but there is still sometimes inadvertent prejudice in single blind studies.

Good double blind studies are much less common than other forms of "scientific reports".

Scientific studies may be done for lots of reasons other than clinical use of a medication. While these are real "scientific studies" and may be useful in the long run, they may not be helpful in determining if there is a valid clinical use for a medication.

Case reports are the most unreliable of studies. Just to give you one example, which I wish I could go into more detail on, I once treated a dog for a condition that had the exact same medication and dosing directions in several textbooks, all of which insinuated that there was a "standard" treatment. Out of curiosity, I researched the references listed, since there was a short list of three or four references in all the textbooks. After looking into these references I was able to discern that ALL of the information presented was based on ONE clinical case report in which a dog was treated with a medication and recovered. Since I didn't want to use the "standard" treatment, I didn't do anything. The dog recovered uneventfully. If I had written the first paper, the "standard" treatment would have been to do nothing. Both "treatments" worked but neither was tested in a scientifically valid manner.

It is critically important to evaluate the validity of information from all published sources, including this one!

I am familiar with Tufts University. At the present time I am not sure who the behaviorists are who are associated with the vet school there but I think that if you ask them they would agree that there are limited numbers of scientifically valid studies done on the clinical use of fluoxetine for any particular behavioral disorder in dogs -- the only ones I know of being a small study on aggression, several on cataplexy (a very rare condition) and a larger study on lick granulomas.

I hope that this makes my statement a little more clear to you and to other readers of this site. I will have to try to come up with a better way to explain when there is information available that has been properly validated and when the information is less valid for clinical situations.

Mike Richards, DVM 4/5/99

Prozac for Dogs

Q: Dear Dr. Mike,I am writing to ask for information about giving Prozac to dogs. I have a 5 yr old male neutered mastiff who is sweet at home with family & friends but unreliable with strangers (dogs and humans). He cannot be walked on the street because he lunges at strangers unpredictably. Due to his huge size, even if I control him, a small lunge looks very threatening to people. Also he might knock over anyone who happened to be carrying or playing with a soccer ball or football (he is extremely ball possessive).

Professional trainers have diagnosed him as having fear or possessive aggression. Also they say he has the intense persistence of the type so valuable in drug seeking or bomb seeking dogs but not so valuable in a pet. I have put extensive effort since his puppyhood into professional training and socialization, and I have experience with obedience competition (in my other dogs). All to no avail. I also have tried different techniques for correction and control, dietary changes, and have had him checked out for physical problems. Crom does have some arthritis but has been made fairly comfortable with Bufferin, and this seems to make him less grouchy (but not more reliable). I am committed to keeping my dog into old age, but I'm concerned that he could be dangerous. Also it isn't fun for him never to go on walks.

I read about Prozac used on dogs in the AKC Gazette but there was no reference to the research studies (on using Prozac for aggression). I have have not been able to find references to these studies on the web. What do you know of this literature? The veterinarians I have consulted about Crom never suggested Prozac or other medication. I would like your pinion and reference to the studies so I can read them for myself. Can you help? Thanks very much!

A: If anyone has published studies on the use of fluoxetine, (Prozac Rx) for aggression in dogs, I am not aware of them. I have corresponded with Dr. Ilana Reisner, a board certified veterinary behaviorist, about the use of these medications. She has been trying them in some cases of aggression and feels that they can be useful.

There are several behavioral modification medications used to treat aggression in dogs. Prozac is one. If I understand the references to it correctly, this has been used mostly to treat dominance aggression. Lithium carbonate is also used for dominance aggression by behaviorists, for some cases. This sort of aggression is usually directed at family members and can occur quite suddenly. Since that isn't the problem you are having, there may be other approaches that might help more. However, I am not a behaviorist and can not claim to be up to date on the latest treatments. So it is also possible that these medications are being used for other forms of aggression and may be useful.

For fear based and sometimes for territorial type aggressive behavior, the preferred medications seem to be anti-anxiety drugs. Among these would be diazepam (Valium Rx) and amitriptylline (Elavil Rx). These medications can reduce anxiety and make a dog a little less likely to respond aggressively to frightening or stressful situations. We have tried amitriptylline for several cases of aggression and feel that it has been helpful in one or two cases only. Most of the time, some sort of behavioral modification is necessary as well.

A good physical exam and general lab profile to rule out underlying problems is always a good idea when assessing aggression. The next best step is consultation with a veterinary or certified animal behaviorist, if possible. In many places, these people are not easily available for consultation, though. A really knowledgeable trainer can be a great help but it is extraordinarily difficult to evaluate trainer's abilities. Assuming there is not a physical cause and that you have exhausted behavioral modification techniques, you are left with muzzling Crom when walking him, which won't help with the lunging but might make people less nervous about him; use of a Promise or halter collar to give yourself more control (this worked very well for our Rottweiler who liked to lunge at people); and finally, medical therapy.

Your vet may be able to at least consult with a veterinary behaviorist. This has helped us on a couple of occasions when the owner simply couldn't make the trip to the behaviorist.

Prozac for dominance aggression

Q: i am looking for some up to date info on the side effects of prozac used in dogs. we are from a veterinary hospital in ontario and are considering putting a 3 year old lhasa on prozac for dominance aggression. we would just like some more technical info. any help would be appreciated. thanks.

A: At the present time the majority opinion seems to be that there are no well defined side effects from fluoxetine (Prozac Rx) in dogs. However, it is important to consider that the types of side effects seen in people would be really hard for a dog to communicate about -- there is no way the dog can say that it feels anxious, isn't sleeping well, feels drowsy or dizzy or nauseated (although vomiting would be tip off here). My best guess is that some of these effects do occur. How serious that might be is hard to say. People quit taking these types of medication when they are bothered by them but our pets don't get that chance.

In theory, fluoxetine should be a good medication to try in aggression --- but you have to be very very careful relying on medication in a situation in which aggression is occurring. Don't take it for granted that the medication will work. Continue to work on behavioral modification as well.

Mike Richards, DVM

Last edited 08/30/02