Heart Medicine Poisoning in Dogs

Close to 170,000 pets get poisoned every year according to the ASPCA and more than 90% are accidental. Although some of these poisonings are not related to heart medication, many of them are, and they are most often due to the owner giving their pet too much medication on accident or by giving the medication too soon after the previous dose. It is vital that you know exactly the dose you need and keep track of it by writing it down on a chart or something similar, posted by wherever you keep your dog’s medication. Heart medication can be a lifesaver for many dogs, but if given too much or too often, it can be serious or even fatal.

It is essential to keep all of your medication out of the reach of your dog. The number one reason for pet poisonings in the United States. Never keep your medication in a baggie or anything other than the medicine bottle, and keep those in a cabinet or somewhere your dog cannot get into. The effects of a toxic amount of heart medication can cause your dog to have a fatal heart attack immediately or it can just build up in your dog’s body and slowly cause damage to the heart, kidneys, and brain. If you think your dog has ingested a toxic amount of heart medication, or any medication, you should call your veterinarian right away, even if they are not showing any symptoms.

Heart medicine poisoning is too much of a certain drug in a dog’s bloodstream at any time either due to accidental ingestion of human heart medication or accidental over dosage when giving a dog heart medication. Some of these heart medications are ACE inhibitors, beta-blockers, calcium channel blockers, cardiac glycosides, and diuretics. Any kind of heart medication can cause poisoning in a dog, even if it is prescribed to them. The toxicity effects can happen immediately (acute) or it can be a long-term effect (chronic) both of which have to be treated as soon as possible to lessen the severity of the damage.

Symptoms will depend on what heart medication caused the toxicity.

ACE Inhibitors (Enalapril, Captopril, Lisinopril)

• Dizziness
• Weakness
• Diarrhea
• Excessive drinking or urination
• Collapse
• Behavioral changes
• Depression
• Bruising
• Nosebleeds

Beta-Blockers (Propranolol, Atenolol, Timolol)

• Nausea
• Vomiting
• Unsteady walking
• Dizziness
• Weakness
• Collapse
• Slow heart rate
• Lethargy

Calcium Channel Blockers (Diltiazem, Amlodipine, Verapamil)

• Nausea
• Vomiting
• Loss of appetite
• Inability to urinate
• Blood in the stool
• Weakness
• Collapse
• Slow heart rate
• Extreme sleepiness

Cardiac Glycosides (Digoxin)

• Drooling
• Nausea
• Vomiting
• Diarrhea
• Abnormal heart rate
• Cardiac arrhythmias
• Weakness
• Lack of energy
• Collapse
• Dilated pupils
• Tremors
• Seizures
• Death

Diuretics (Chlorothiazide, Hydrochlorothiazide, Furosemide)

• Severe dehydration
• Excessive thirst and urination
• Weakness
• Lethargy
• Renal failure
• Heart attack

 Types

There are two types of heart medicine poisoning in dogs, acute and chronic. There are also several kinds of heart medications, which are ACE inhibitors (enalapril, captopril, Lisinopril), beta-blockers (propranolol, atenolol, timolol), calcium channel blockers (diltiazem, amlodipine, verapamil), cardiac glycosides (digoxin), and diuretics (chlorothiazide, hydrochlorothiazide, furosemide).

• Acute poisoning effects happen immediately, such as vomiting, difficulty breathing, seizures, collapse
• Chronic poisoning effects happen over a period of time and can continue to do damage to your dog’s internal organs for the rest of their life

• Accidental overdose by owner
• Accidental ingestion by dog
• Intentional poisoning
• Drug interactions such as with neomycin, tetracycline, furosemide, glucocorticoids, diltiazem aspirin, flecainide and many more. Check with your veterinarian for a complete list if your dog is taking any kind of heart medication.

These medications should not be used if your dog has any of these conditions unless your veterinarian prescribes it while knowing the situation:

• Idiopathic subaortic stenosis
• Heart failure with glomerulonephritis
• Myocarditis
• Acute myocardial infarction
• Ventricular tachycardia
• Chronic obstructive pericarditis
• Incomplete AV block
• Premature ventricular contraction
• Pulmonary disease
• Carotid sinus sensitivity
• Hypoxia
• Renal disease
• Thyroid disease
• Hypokalemia

The diagnosis of your dog’s poisoning is usually as simple as a blood test, but the first thing your veterinarian will want to do is to make sure your dog is stable and out of danger. The veterinarian will want to know your dog’s complete medical history and any medications he is on or has been on recently. A complete physical examination will be done as well as some tests. These tests are:

• Complete blood count (CBC)
• Blood gases
• Blood chemical panel
• Urinalysis
• Electrocardiogram (EKG or ECG)
• Echocardiography (ultrasound of the heart)
• Echocardiography (Doppler ultrasound of the heart)

If your dog ingested medication and has an acute reaction, your veterinarian will empty your dog’s stomach with activated charcoal as many times as needed to remove the toxins. Hospitalization will be needed in most cases. Medication will then be given to control the effects if necessary.

If the problem is a chronic build-up of medication over time, the veterinarian will more than likely stop the medication while determining the cause of the toxicity. It may just be that the dosage needs to be changed.

Some medications that may be used to help stop the effects are atropine to treat bradycardia or heart block, lidocaine for ventricular arrhythmia, and phenytoin to block the AV node effects.

Recovery will depend on what heart medication caused the toxicity, what damage has already been done, and how soon the treatment was started. Generally, if your dog was treated within a few hours and the effects were stopped before irreversible damage has been done to any vital organs, chances for recovery are excellent.

If the damage could not be stopped or reversed, the damage that has already been done will continue to get worse and will have to be treated for life. If the effect is congestive heart failure, the disease will progress until they get too bad to sustain life. This could be a year or more or it could be weeks, depending on the damage already done.