The top 3 human medications pets ingest in 2019

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No matter if you work in general, emergency or specialty practice, you'll likely see veterinary patients present with clinical signs of ingesting human prescription medication. In order to be prepared to handle these cases to maximum efficiency, we gathered these tips from Justine Lee, DVM, DACVECC, DABT, who presented a session on this topic at a recent industry conference.

Here we'll take a look at the basics of the top three categories of toxicosis she's seeing, her biggest concerns and takeaway treatment tips to tackle these cases and help pets recover as quickly as possible.

Human prescription cardiac medications

The basics: Cases of pets ingesting human cardiac medications are especially common in areas of the country with higher populations of elderly people, like Florida. Often times a dog will get into the weekly pill holder, resulting in polypharmacy ingestions. Polypharmacy cases are best managed by poison control agencies, such as the ASPCA-most people don't know the exact names or doses of their medications.

Biggest concern: The two cardiac medications to really worry about are calcium channel blockers and beta blockers.

Calcium channel blockers work by inhibiting the extracellular influx of calcium in vascular smooth muscle and cardiac cells, resulting in hypotension. Common names of drugs in this class include Diltiazem, Norbax and Amlodipine.

Beta blockers often end with “-ol” and have names like Propranolol, Timolol and Sotalol and are commonly used therapeutically in veterinary medicine. However, when ingested by animals at more than two to three times the high end of the dose, beta blockers can cause life threatening complications. These drugs work by causing relaxation of the heart, bradycardia and lowering of blood pressure. In animals with poisoning, the side effects are severe hypotension and bradycardia. Indirectly, this can cause poor perfusion to the kidneys, which can be life threatening.

Treatment tips: A severe calcium channel or beta blocker toxicity should be treated aggressively. If the patient is asymptomatic, induce vomiting right away and then administer activated charcoal. The animal should then be placed on intravenous fluids to increase perfusion and blood pressure and heart rate should be monitored. Bradycardia can be treated with repeated doses of atropine. If the patient is not responding to multiple doses of atropine, Dr. Lee advises referring to a specialty hospital, as some of these cases need to be very aggressively medically managed.

Antidepressants and selective serotonin reuptake inhibitors (SSRIs)

The basics: The second most common type of human medication dogs and cats ingest are antidepressants and SSRIs. SSRIs are designed to increase the amount of serotonin in the human body, causing relaxation and elevated moods. However, the result of dogs or cats ingest these drugs is often a profound serotonin syndrome.

Biggest concern: Brand names to recognize include Prozac and the chewable form Reconcile as well as Zoloft, Cymbalta, Luvox, Lexapro and Effexor XR. Practices that treat a lot of cats should pay special attention to cases involving Effexor XR, as it has some odor or ingredient that cats seem to purposefully seek out.

Treatment tips: SSRIs work by inhibiting the reuptake of serotonin at the presynaptic membrane. Clinical signs of serotonin syndrome in pets include tachycardia, hypertension, mydriasis, tremors and even seizures. Dogs with serotonin syndrome will be very agitated-think bouncing off the walls-whereas cats can be quite sedate. Cats tend to have severe mydriasis, panting, hyperthermia; often the tail will be very puffed and they can be very angry and upset. In severe cases cats can also experience tremors and seizures. [Note: We'll touch on treatment tips specifically for antidepressants in the next section, which discusses amphetamines.]

Amphetamines

The basics: As you're probably aware, amphetamines make up a large part of a multi-billion dollar pharmaceutical industry in the U.S., meaning you're likely to see these toxicities in pets. These drugs are legally prescribed to humans for a number of reasons, including for children with Attention Deficit/Hyperactivity Disorder, and for use as sympathomimetic stimulants to help with narcolepsy and weight loss in adults.

Biggest concern: Brand names like Ritalin, Concerta and Adderall. Because these are stimulant drugs, the clinical signs pets develop after ingestion as similar to those seen with antidepressants; these include tachycardia, agitation, hypertension, mydriasis, tremors and seizures. However, the agitation and tremoring can be much more severe with amphetamines. “Most of the time I feel pretty comfortable letting owners try to induce emesis at home with hydrogen peroxide. With antidepressants and amphetamines I am a little more conservative,” Dr. Lee says. This is because clinical signs in pets can develop very quickly. Rather than have an pet owner spend time trying to calculate the dose of peroxide, or redosing, Dr. Lee says it's safer if they come straight to the clinic.

Treatment tips: If the patient is asymptomatic, absolutely induce emesis right away. However, if the pet is already tremoring or tachycardic, it is too late to induce emesis. If, after emesis, the patient continues to be asymptomatic, follow up with one dose of activated charcoal. If a patient has ingested Effexor XR, the “XR” indicates a sustained release medication that can be taken every twelve hours. This drug comes as enterically coated beads in a capsule and is not meant to be chewed. Except dogs and cats don't swallow ... they chew. As a result, upon the pet's ingestion of human extended release medications, clinical signs will appear sooner and last for a more prolonged period of time.

With these patients, adding extra doses of activated charcoal every six hours for three to four more doses can be beneficial. With cats, usually two doses is the maximum the patient will allow. Intravenous fluid therapy will help keep pets normothermic if they are tremoring. Rarely, in a tremoring or seizing toxicity case, myoglobin can lodge in the renal tubules resulting in renal issues. Fluid therapy helps to prevent this unusual complication.

Body temperatures should be monitored, and if the pet is extremely hyperthermic, a drug to reduce tremoring (such as methocarbamol) will be sufficient. Monitoring should be done every two to four hours to ensure the pet is not tachycardic or hypertensive. If the heart rate are above 180 beats per minute, Acepromazine at 0.05 - 0.1 mg/kg can be given in several repeated doses up to 3 mg total and the response is typically positive.

What if the pet is still tachycardiac? A beta blocker, like propranolol, should be used. Unfortunately, when activated charcoal has been administered, nothing will absorb orally, so injectable propranolol must be used. Another useful therapy for SSRIs and amphetamines is the old appetite stimulant, cyproheptadine (Periactin). This is a serotonin antagonist. It is extremely benign and can be given every six to eight hours. It's a useful therapy for patients that may have to be treated on an outpatient basis due to financial limitations. Finally, sometimes a true anticonvulsant is required when animals are experiencing seizures. Diazepam, Keppra, or phenobarbital intravenously are appropriate choices to stop the seizure activity.

Bonus: Marijuana

The basics: The active ingredient in marijuana is tetrahydrocannabinol (THC). Veterinary practitioners may see a spike in THC toxicosis cases due to the increase in human medicinal marijuana use. While dogs rarely die from marijuana overdose, they do develop clinical signs at 1/1000th of the lethal dose (still, the actual toxic dose in dogs in unknown). Clinical signs are not something seen in cats; it is more of a canine toxicity.

Biggest concern: Clinical signs generally evidence three to four hours after ingestion and resolve within 24 hours. Inhalation exposure is very rare; most ingestions are accidental and are of dried, cured plant buds or baked goods. Pot butter ingestion can be fatal and should be treated more aggressively when this is known to have happened. Pot is extremely lipophilic and when mixed with butter, the THC is very rapidly absorbed.

Clinically, the majority of dogs who present with THC toxicosis will display ataxia, about half will display mydriasis and disorientation, some are super sedate or “stoned,” some are hyperesthetic, tremoring and vomiting. One sign that is classic for marijuana ingestion is sudden urinary incontinence. Bradycardia and hypoventilation can be quite severe, even life-threatening, and some severely affected animals may even require ventilation.

Treatment tips: Treatment is symptomatic supportive care and occasionally acepromazine for highly agitated patients. In very sedate animals, further sedation is to be avoided. With fluid therapy, gastric lavage, activated charcoal and nursing care, most of these cases do quite well.

Editor's note: We recently covered another worrisome topical human medication that's proving fatal when ingested by pets: 5-fluororacil. Get all the details here, and be aware that human healthcare professionals may not be adequately warning their patients of this product's danger to pets.