Methylphenidate Poisoning in Dogs

Methylphenidate (also called Ritalin) is an amphetamine related drug that works as a central nervous system stimulator. In humans, it is prescribed most commonly for hyperactivity and attention deficit disorders, but it can also be given to treat mood disorders, fatigue, obesity, and sleep paralysis. In dogs, methylphenidate can be used to treat narcolepsy, cataplexy and some types of hyperactivity, but it is not as safe in dogs as it is in humans and most veterinarians prefer to use drugs with fewer side-effects. Overdose of a dog’s own prescription or ingestion of a medication intended for humans can cause methylphenidate poisoning in dogs. Methylphenidate toxicosis is similar to toxicity from other amphetamine drugs, both legal and illegal.

Dogs have CNS symptoms including tremors, seizures and behavior changes as well as cardiovascular, gastrointestinal, and respiratory problems. One study found that the intensity of symptoms did not always correspond to the amount ingested, so it’s important to get treatment even if the overdose was relatively small. Extended release formulas have been found to be more toxic for dogs than other forms of the drug. Symptoms usually develop quickly, but with slow release drugs they may be drawn out over a period of hours or even days. The veterinarian will be able to reduce absorption and help to make the symptoms less severe. Without treatment, methylphenidate poisoning can quickly be fatal.

Methylphenidate is found in many drugs that are used to treat ADHD and other mood disorders in humans. It can also be prescribed for narcolepsy and hyperactivity in dogs. Side-effects are common and methylphenidate poisoning or toxicosis can have severe life-threatening symptoms.

These are the symptoms you will notice in a dog with methylphenidate poisoning. Get veterinary treatment immediately.

• Restlessness
• Hyperactivity
• Aggression
• Panting
• Vomiting
• Drooling
• Diarrhea
• Increased body temperature (hyperthermia)
• Tremors
• Lack of muscle control (ataxia)
• Increased heart rate (tachycardia)
• Hypertension
• Dilated pupils (mydriasis)
• Abnormal movements like circling or head bobbing
• Seizures

Types

These are some of the brand-name medications that contain methylphenidate. 

• Ritalin
• Concerta
• Quillivant XR
• Daytrana

Methylphenidate containing medications are only registered and approved by the FDA for humans, but a veterinarian could legally prescribe them to your dog as an extra label drug.

These are the most common risk factors for methylphenidate poisoning.

Accidental overdose (either taking human medication or overdose of a prescribed medication):

• Intended dose left on the table
• Bottle left uncapped
• Dog chewed through the bottle
• Improper storage

Overuse of a medication prescribed for your dog:

• Giving more than the prescribed dose
• Accidentally giving medication twice

Methylphenidate poisoning resembles many other types of amphetamine toxicity, so it can be difficult to diagnose symptomatically. It is also very similar to cocaine poisoning, although symptoms will be of somewhat longer duration. The veterinarian will perform a complete physical examination as well as taking blood and urine samples. These can help to rule out infection if you didn’t see the incident and are not sure what is causing your dog’s symptoms. Exposure to medication containing methylphenidate is the easiest way to diagnose the condition, however urinalysis and stomach content samples frequently have evidence of toxicity from amphetamine related drugs. Bloodwork will only be positive if a large amount was ingested.

The veterinarian will need your dog’s complete medical history and a list of current medications, as well as any potential exposure to human medications. If you know what substance your dog ingested, bring the bottle so the veterinarian can identify any potential toxicity. A detailed description of your dog’s symptoms and time of onset may also be helpful.

Initial treatment will focus on reducing absorption. If the poisoning was recent, the veterinarian will induce vomiting and may perform gastric lavage under anesthesia. Activated charcoal may be given which will bind to the drug in the gastrointestinal tract and help to limit absorption into the bloodstream. If you don’t have immediate access to veterinary treatment, calling a poison helpline can be helpful. You will need to tell the agent exactly what you think your dog ingested, as well as give details about your dog’s weight and breed. Don’t induce vomiting unless it is recommended by a professional.

Methylphenidate containing medications are fast acting and typically reach their peak in 1-2 hours. If they are delayed release doses, symptoms may continue to manifest for 8-30 hours depending on the acid content of the urine. The veterinarian will try to reduce the severity of the symptoms during that time by giving IV fluids, controlling body temperature, and monitoring heart rate and blood pressure. Phenothiazines or other anticonvulsants may be given to treat seizures. Cyproheptadine may help with symptoms of agitation and disorientation. Ascorbic acid may be prescribed to increase urine acidity and encourage faster elimination through the urine. Dogs are frequently also sedated. Your dog will need to stay in a veterinary hospital until all systems have returned to normal.

Most dogs will recover from methylphenidate poisoning with treatment, but since the medication is fast acting, fatal symptoms can develop quickly. Avoiding exposure is the best way to manage the condition. Store all medications on a high shelf that your dog can’t access. Separate dog and human medications to avoid confusion and keep all bottles sealed. A dose should be given as soon as it is removed from the bottle. Don’t leave pills on the table where your dog can eat them.

If your dog is prescribed a medication that contains methylphenidate, discuss the dangers and side-effects with a veterinarian. Make sure other treatments have been tried and the drug is really in your dog’s best interest.  Doses should be given at a regularly scheduled time and recorded accurately so there is no double dosing. If you forget a dose, give it as soon as possible, but if it’s too close to the next medication time it’s better to skip a pill than give two at once. Never give your dog extra doses unless it’s specifically recommended by a veterinarian.