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Rimadyl Dosage for Dogs – The Science Behind the Side-Effects

The Rimadyl dosage for dogs is calculated at 2 mg per pound of body weight. That dosage can be administered once per day, but it can also be divided in half and administered twice daily.

Rimadyl is a prescription-based non-steroidal anti-inflammatory used to treat painful conditions like arthritis, hip dysplasia, or soft-tissue injuries in dogs. It is also used for post-operative pain.

Are you worried about giving your dog an NSAID? There are a lot of alarmist articles about Rimadyl dosage for dogs, but are they true? Unfortunately, some dogs do have a severe allergic reaction to Rimadyl. The reality is, there are risks to all medications.

Most allergic reactions are mild to moderate and do not cause the dog long-term health problems if the medication is stopped.

Technically, it’s best to stick with a veterinarian who gets to know your dog and has a history of health records.

Understanding your dog’s particular needs are important when prescribing because underlying health conditions and other medications can have an impact on the medication’s safety.

How Your Veterinarian Determines Rimadyl Dosage for Dogs

Evaluation for any pre-existing conditions and regular monitoring are recommended for pets on Rimadyl.

Technically speaking, the veterinarian should order a blood panel to ensure your dog does not have any kidney or liver problems prior to recommending a Rimadyl dosage for dogs.

When speaking with the veterinarian, make sure to tell him or her about any supplements, over-the-counter medications (including herbal preparations) and mention any allergies (including food allergies) your dog may have.

When determining Rimadyl dosage for dogs, it’s important that the veterinarian have as much pertinent information as possible.

Rimadyl is designed for short term use.

Potential Side-Effects of Rimadyl for Dogs

I’m a dog owner myself, and I hate to see my dogs in pain. As they age, however, I’m noticing a lot more limping from joint pain and stiffness. If it gets bad enough, I wouldn’t hesitate to give either one of them a prescription drug like Rimadyl.

Yes, there are some risks, just like there are risks when you or I take prescription or over-the-counter drugs.

Rimadyl dosage for dogs, like other NSAIDs, are designed for short-term use. Short-term use, loosely defined, would be a couple of weeks at most.

Your veterinarian, however, may have very good reasons for wanting to extend that guideline. The reason NSAIDs are usually only delivered short-term is to reduce the risk of gastrointestinal side-effects. Other potential side-effects include:


Dogs vomit from time-to-time whether it’s because of Rimadyl, or some other benign cause. There’s no reason to panic if your dog regurgitates a bit when first taking Rimadyl.

However, if your dog continues to vomit and obviously isn’t getting enough food or water because of it, seek the help of your veterinarian.


Sometimes it takes a couple of days for your dog to adjust to a new medication. Diarrhea and vomiting are probably the more common side-effects of Rimadyl for dogs.

Again, a few loose stools is nothing to worry about. However, if your dog is still a puppy there’s a higher risk of dehydration so you’ll want to watch that. Stick to a bland diet when your dog first begins taking Rimadyl to help ease stomach upset.

Black Poop

Any change in diet, stress, or medications could change the color of your dog’s poop temporarily.

Black poop is definitely a warning sign that something more serious is going on. Black poop can mean that blood is present from an internal bleed.

Not what you want to see! I would definitely stop the medication and contact the veterinarian ASAP.

Don’t panic, but don’t ignore it. Rimadyl dosage for dogs should follow the 2 mg per pound administered once daily (or divided into two half doses).

Dogs on a higher dose than needed may be more at risk of severe side-effects. The side-effects listed here are more common in long term use of NSAIDs like Rimadyl.


You’ll know when your dog is constipated because he/she will strain a lot when trying to poop.

Your dog might manage to poop a little bit, or will move from place-to-place leaving only a tiny amount of feces behind. In some cases, he/she might not be able to go at all.

The importance of Rimadyl dosage for dogs is to lessen the chances of side-effects like these from happening.


My dog was recently prescribed Rimadyl to help ease the pain of sore leg and I noticed she did sleep more. That only lasted a short while and she was soon back to her normal self. Sleep, in fact, is good for dogs trying to recover from an injury.

Sleep is when the body heals itself. So, a little fatigue in the early days is okay. If you believe your dog is overly groggy, consult the veterinarian.


What does weakness look like in a dog? A weak dog simply won’t be up to doing much. His paws might be a little limp, he won’t feel like getting up and moving around, and he might not even want to jump up onto his favorite bed or sofa. You’ll know because your dog just won’t be himself.

Gastrointestinal Ulcers

Now we’re getting into some much more serious side-effects. Gastrointestinal ulcers are sores that wear into the gastrointestinal lining of the stomach.

In fact, if your dog is showing signs of weakness (above), it could be due to ulcers. Ulcers can cause an internal bleed which, in turn, can lead to black poop as discussed above.

You can’t see gastrointestinal ulcers. The red flags come from some of the other side-effects listed above.

I don’t suggest waiting any time to seek veterinarian care if this happens. The Rimadyl dosage for dogs can be tweaked by your veterinarian, based on his or her own medical conclusions.

WHY Does Rimadyl Cause These Side-Effects?

Any NSAID, including Rimadyl, works by blocking the production of Prostaglandin. Prostaglandin is produced by an enzyme called cyclooxygenase or COX for short. When cells are damaged in some way, this enzyme triggers prostaglandin to get to work.

The prostaglandin protects the lining of the stomach and intestines. It also helps keep the blood flowing to the kidneys.

Prostaglandins also work uniquely by causing pain and that pain signifies that something is wrong. If we (or our dogs) didn’t experience any pain, we wouldn’t have any incentive to repair the damage.

When NSAIDS are introduced, their primary function is to block the production of prostaglandin.

When that substance is blocked, the pain stops or at least eases. Unfortunately, blocking prostaglandin also leaves the gastrointestinal tract vulnerable to stomach acid.

The stomach acid eats away at the lining and before you know it, your dog has an ulcer.

Once your dog has an ulcer, all of the side-effects listed here can start to take effect. Vomiting, bloody stool, weakness, no appetite, etc., can all be attributed to ulcers.

Rimadyl dosage for dogs that is too high should be adjusted or discontinued; however, always seek help from a licensed veterinarian.

Sores in the Mouth

Non-steroidal anti-inflammatories like Rimadyl can cause gastrointestinal acid to build and that acid, present in the saliva, can create a pH imbalance.

That imbalance can cause sores to develop in your dog’s mouth.

Keep in mind that there are other reasons for sores in your dog’s mouth and it may not be related to the rimadyl at all.

Dogs can develop warts in their mouths (papillomas), canker sores, abscessed gums, etc.

Fluid Retention and Weight Gain

Firstly, the weight gain is temporary and is caused by the build-up of fluids in the tissues. Fluids build up when the kidneys are not working properly.

If you’ll remember from above, prostaglandins (although they cause pain in the body) are useful in maintaining the flow of blood to the kidneys.

Unfortunately, you can’t just block the bad things prostaglandins do. You also have to block the good things they do. The result can be impaired kidney function.

This will cause severe fluid retention and weight gain. As a result, you might notice increased or decreased thirst in your dog.

Kidney damage can present itself in the color, smell, and frequency of urination in dogs.

Rimadyl is used to treat painful arthritis and hip dysplasia

Keep in mind that more serious side-effects like kidney damage usually occur with long-term use of NSAIDs or from improper dosing.

Muscle cramps

If your dog experiences muscle cramps while on Rimadyl, it’s probably caused by a sequence of events that starts with vomiting and diarrhea.

All bodies need electrolytes. Electrolytes are the minerals we take in through our food. These minerals ensure that our body’s have the right pH balance, water balance, and work to move vital nutrients into our cells. It all works in the same in dogs.

If your dog experiences prolonged vomiting and diarrhea, or has kidney or liver problems, the result could be muscle cramps.

This is the result of an upset in the balance of electrolytes in the body. In some situations, the veterinarian may want to re-evaluate the Rimadyl dosage for dogs.

Rimadyl Dosage for Dogs The Science Behind The Side Effects
The Rimadyl dosage for dogs this small is 2 mg/pound


Sadly, Rimadyl can be toxic for some dogs and that toxicity can lead to seizures. If your dog has any history of seizures, make sure to tell the veterinarian (especially a veterinarian your dog has never seen before). He/she may decide on a different drug.

Abdominal Pain

Abdominal pain is one of those things that can be caused by a variety of situations. Constipation can cause pain in the tummy, just as too much gastrointestinal acid can cause pain.

Obviously, your dog can’t tell you he or she has abdominal pain, but you’ll notice in a sudden change in eating habits.

The lower the Rimadyl dosage for dogs, the less likely he/she will have severe side-effects including abdominal pain.

Behavioral Changes

I’m not very pleasant when I’m sick and maybe that could be classified as “behavioral change”.

If your dog isn’t feeling well, you might notice changes in the way he or she normally acts. He might whine, cry, howl, bark, or simply withdraw.

You know your dog best. Mild changes in appetite or fatigue are common side-effects. Noticeable changes in behavior are not.


Jaundice, which is evidenced by yellowing of the skin and the eyes, is the result of liver damage.

The liver is necessary for filtering toxins through the body. When it’s damaged, those toxins build up in the body. Rimadyl dosage for dogs that is too high may put your dog at higher risk of severe side-effects.

Liver or kidney problems are two problems that can be associated with long-term use of Rimadyl.

Read this article by the FDA on pain relievers in pets!

How to Administer Rimadyl Dosage for Dogs

Rimadyl comes in chewable, liver flavored treats, capsules, and in an injectable formula. If your veterinarian has decided to prescribe Rimadyl, you don’t need to worry about your dog actually taking it.

If it were me, I would give my dog the liver flavored option, simply for ease of use. That way, I know my dog wouldn’t spit it out or clamp his mouth shut when trying to administer it.

The drug comes in 25 mg, 75 mg, and 100 mg options and, of course, is dosed according to the size of your dog. Do not increase or decrease the dose unless the veterinarian has ordered it.

Increasing the dose can worsen any side-effects, and decreasing the dosage could lower the effectiveness of the drug. At that point, if the drug isn’t reducing pain, there’s no sense being on it.

Rimadyl can be fed by hand or mixed with food.

How to Reduce the Risk of Adverse Side Effects

There’s no magic way of ensuring your dog won’t have any side-effects from Rimadyl. However, the chances of severe side-effects are lowered when the drug is used as a short-term option.

Communicate openly with the veterinarian and be sure to tell him/her about any other over-the-counter drugs/supplements you’ve been giving your dog.

Products advertised as “all natural” or “holistic” do not necessarily mean safe. Herbal supplements, can have serious interactions with prescription medication.

Make sure to get the prescription directly from your veterinarian. Although it’s tempting to save a few dollars, never take NSAIDs (or other prescriptions) from well-meaning friends or family. For one thing, the prescription could be outdated.

More importantly, it’s never a guide idea to treat your dog without a full checkup by the veterinarian.

Summing Up Rimadyl Dosage for Dogs

At the end of the day, we all just want our dogs to be happy and healthy. Yes, there are situations when medications like Rimadyl are not appropriate. If your dog has had a bad experience with the drug in the past, there’s a good chance that hasn’t changed.

Remember that Rimadyl is designed for short-term use or on an as-needed basis. Prolonged exposure and higher dosing are more likely to cause side-effects.

Rimadyl can be a great short-term option for getting pain under control.

However, your veterinarian should also be working with you to develop a plan that will address the underlying cause. For example, if your dog has arthritis pain, the veterinarian might suggest a weight-loss plan along with exercise that is easy on the joints (like swimming).

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