Previcox(®) (firocoxib) is a medicine most commonly used to relieve arthritis-related pain in dogs. It is an NSAID (nonsteroidal anti-inflammatory drug) which, like other drugs of this type, can also be used to treat inflammation and fever. The drug works by blocking the actions of special enzymes known as “COX-1” and “COX-2”. These enzymes play a key part in the formation of “prostaglandins”, a type of lipid found around areas of infection and tissue damage. By inhibiting the production of prostaglandins the medicine can effectively bring down swelling, pain and fever.

How does it compare to other NSAIDs?

Unlike most other NSAID drugs firocoxib mainly inhibits COX-2 enzymes. By sparing COX-1 enzymes the medicine should not be as harsh on the kidneys.

Recommended Dosage

Note: Always speak to your vet before giving Previcox to your dog.

Previcox should only be used to treat dogs who weigh 12.5 pounds or more. The usual dosage is 2.27 mg/lb (5 mg/kg) and can be given once daily.

Dosage of firocoxib for dogs

The medicine is available as 57 mg chewable tablets or 227 mg chewable tablets which can be used depending on the size of your dog. You should calculate the dosage in half-tablet increments. Your dog should experience a relief of pain within just a few days.

In one study, a dosage of 2.27 mg/lb once per day was used off-label to treat transitional cell carcinomas. It was used in conjunction with cisplatin (given by IV injection at a dosage of 60 mg /m2 every 21 days). Previcox has been shown to greatly increase the antitumor effects of cisplatin.

Should I give this medicine to my dog with food?

It can be given either with or without food depending on your personal preference.

Example Dosage: A 50 lb dog would need one half of a 227 mg tablet once daily.

Is It Safe?

Most dogs will tolerate the drug well and experience a good level of pain relief when it is used at the recommended dosage. There are a few possible side effects but the most common reactions are not likely to be dangerous.

Dogs should be monitored extra carefully if they:

  • Have poor kidney, liver or heart function
  • Are dehydrated or hypovolemic
  • Have low blood pressure
  • Are being treated with diuretics
  • Have any bleeding disorders
  • Have peptic ulcers

This medicine may not be suitable for dogs if maintaining their weight is important as Previcox may cause a loss of weight and appetite.

Pregnancy Notice: Avoid giving this medicine to a pregnant dog.

Safety Guidelines

To increase the safety of treatment you should follow these guidelines:

  • Have the vet take baseline tests (physical condition and blood testing)
  • Do not give to dogs who have reacted badly to NSAIDs in the past
  • Do not give to dogs weighing less than 12.5 pounds
  • Do not exceed the recommended dose
  • Do not use alongside other NSAIDs
  • Avoid giving to a pregnant dog

You should pay special attention to any adverse reactions. Contact the vet if your dog experiences vomiting, loss of appetite/weight, diarrhea, behavioral changes, changes in thirst or urination, blood in stools/vomit or yellowing of the eyes.

Switching medicines?

If you decide to stop treating your dog with this medicine and begin treatment with a different NSAID it’s best to not administer firocoxib or any other NSAID drug for a 5 day period.

What Is It Used For?

You can use Previcox for dogs with fever, swelling and pain in general (control of post-operative pain using this medicine is another possible use).

Side Effects

Because the drug primarily inhibits the “COX-2” enzyme rather than the “COX-1” enzyme it should (in theory) be milder on the kidneys and gastrointestinal function than most other NSAID medicines. Possible side effects include:

Most Common

  • Vomiting
  • Loss of appetite
  • Weight loss


  • Diarrhea
  • Depression
  • Lethargy
  • Loss of coordination
  • Blood in vomit or in stools
  • Peptic ulcers

Contact the vet about any bad reactions your dog experiences. Traces of blood in stools and vomit indicates internal bleeding and should be treated by a professional immediately.


Overdoses of this medicine can be fatal. Always call the vet or ASPCA Poison Control Hotline (888) 426-4435 if an overdose occurs.


Dr. Bruce
Merial (manufacturer)
Plumb’s Veterinary Drug Handbook (sixth edition)