Naproxen Poisoning in Dogs

Naproxen is an over the counter NSAID that is used to treat pain, inflammation, and fever in people and dogs. Naproxen has typically been prescribed for dogs at a dose of 2 milligrams per kilogram of body weight every other day. Due to the side-effects, many veterinarians recommend only using naproxen if other medications are ineffective. 

Naproxen works by blocking the enzyme cyclooxygenase which helps to limit fever and inflammation responses in the body. However, cyclooxygenase also produces prostaglandins that protect the gastrointestinal tract and help with blood flow and filtration in the kidneys. Inhibition of this enzyme can result in bleeding and ulceration of the GI tract as well as reduced kidney function. 

Dogs have been known to develop vomiting, lethargy and bloody stools after only a single dose of naproxen and week-long regimens can result in signs of kidney dysfunction, especially if they don’t adequately account for the dog’s weight. 

The Animal Poison Control Center had 4,404 reported cases of naproxen poisoning from 2001-2011, both from naproxen that was prescribed to dogs and accidental overdoses of human medication. Single doses as low as 7 mg per kg can have significant symptoms, while 13-15 mg per kg will cause signs of kidney failure with increased blood nitrogen. 

Gastrointestinal symptoms will become apparent in 2-24 hours, while kidney dysfunction develops in 24-48 hours. Use of other NSAIDs can compound the problem and older dogs with prior kidney disease are also more at risk. Severe overdose can lead to fatal bleeding in the GI tract and acute kidney failure if left untreated. Most symptoms of naproxen poisoning can be resolved with treatment and kidney dysfunction is usually reversible as long as there are no complicating diseases or toxicities.

Naproxen is a non-prescription NSAID that is used to treat fever, inflammation, and pain in humans. It is also prescribed to treat these conditions in dogs, however high doses can have toxic side-effects. Naproxen poisoning in dogs can cause ulcers, gastrointestinal bleeding, and kidney failure.

Paying to treat naproxen poisoning out of pocket can be a major financial burden. Fortunately, most pet insurance companies reimburse claims within 3 days, putting 90% of the bill back in your pocket. In the market for pet insurance? Compare leading pet insurance companies to find the right plan for your pet.

Get veterinary treatment as soon as possible if you notice any of the following symptoms associated with naproxen toxicosis.

• Frequent vomiting (with or without blood)
• Abdominal pain
• Lack of appetite
• Weight loss
• Lethargy
• Blood in the stool which may be red or black(melena)
• Gum ulcers
• Pale mucous membranes
• Weakness
• Stumbling

Types

These are the brand names for some over-the-counter human medications that contain naproxen.

• Aleve
• Anaprox
• Mediproxen
• Naprelan
• Naprosyn

These are the most common risk factors associated with naproxen poisoning.

• High doses of naproxen prescribed to dogs
• Owners giving naproxen intended for humans to dogs
• Combining Naproxen with other NSAIDs

Accidental overdose of medication for dogs or humans can occur due to :

• Improperly stored medications
• Bottle left open
• Dog chewing through bottle
• Sugar coated pills that taste good to dogs

The veterinarian will physically examine your dog and take blood and urine samples. Blood tests will show regenerative anemia from blood loss as well as increases in BUN (blood nitrogen) and creatinine if kidney failure is present. The veterinarian will need a list of your dog’s current medications and a detailed description of the symptoms. In the case of accidental overdose, bring the empty container or a sample of the medication you think your dog ingested so the veterinarian can evaluate it. The veterinarian will want to know when you think the exposure took place as well as how much your dog may have ingested.

Calling a poison helpline can be a good first step for naproxen overdose, especially if you don’t have immediate access to a veterinarian. Have the medication on hand, as well as your dog’s breed and weight. Follow the instructions the agent gives you and get in-person veterinary attention as soon as possible. Only induce vomiting if specifically directed by a professional.

If your dog is developing mild symptoms from a naproxen prescription, the veterinarian will discontinue the medication and treat the symptoms as necessary. Larger doses will require more aggressive treatment. If ingestion took place in the last 2 hours, the veterinarian will give your dog medication that causes emesis. Activated charcoal may also be given to help limit availability in the gastrointestinal tract and a cathartic medication will help to encourage excretion through bowel movements. A second dose of activated charcoal may be administered 24-48 hours later to limit recirculation from the liver.

Intravenous fluids and electrolytes will help to balance sodium levels which can rise as a result of activated charcoal administration. Various medications may be used to protect the GI tract, including sucralfate, misoprostol, famotidine, or omeprazole. If significant GI bleeding develops, blood transfusions may be necessary to reduce anemia and prevent fatal blood loss. 

If kidney failure is a possibility, the veterinarian will monitor blood and urine levels and provide fluid treatment as needed to dilute toxins that are normally filtered by the kidneys. Symptoms of naproxen toxicity can continue to increase over a 72 hour period, so the veterinarian will need to monitor your dog during that time. For severe overdose, your dog will need to stay in a veterinary hospital for 3-4 days or until all systems have returned to normal.

Dogs often make a complete recovery after treatment for naproxen poisoning, but there is always a risk of fatal bleeding complications or kidney failure. If your dog is prescribed naproxen, discuss the risk of side-effects with your veterinarian and make sure your dog is on the lowest possible dose. Never give dogs any medications intended for humans. 

Keep all medications in your house on a high shelf or in a closed medicine cabinet that your dog cannot access. Close all bottles and avoid leaving them around since dogs may be able to access the pills by chewing through the bottle. Sugar coated pills can be an incentive, especially if your dog is already familiar with the taste.