Antidepressant Toxicosis in Dogs

Antidepressants have become more widely prescribed for both dogs and humans. As a result, antidepressant toxicosis is becoming more and more common in dogs.

Among the most common medications to cause toxicosis there are:

• Selective serotonin reuptake inhibitors (SSRIs), such as paroxetine, fluoxetine, and sertraline
• Tricyclic antidepressants, such as amitriptyline and clomipramine
• Monoamine oxidase inhibitors (MOIs) such as selegiline

The prognosis is generally good to guarded in mildly affected dogs. The prognosis becomes poor in severe cases where seizures or other life-threatening symptoms are present.

Antidepressant toxicosis is a potentially deadly condition and prompt treatment is necessary for a better prognosis. As such, it is considered an emergency requiring immediate veterinary assistance.

Dogs living in homes where antidepressants are stored are at risk of accidental ingestion or overdose. In the event of accidental ingestion, small dogs are more likely to take a toxic dose than larger dogs as toxicity scales with body mass.

Symptoms of antidepressant poisoning in dogs may vary depending on the medication ingested, the amount ingested, and the speed of consumption. Severe cases can present with cardiac and respiratory effects such as arrhythmia, tachycardia, and difficulty breathing or abnormally slow breathing.

Clinical signs can progress to seizures, coma, and death in a matter of hours in severe cases if not treated promptly.

Most commonly, antidepressant toxicosis is due to accidental ingestion of antidepressant drugs. Other possible causes include inappropriate administration such as giving too much medication or too quickly, and accidental overdose during therapeutic use.

The diagnostic process relies on a complete physical examination and a thorough history. Usually, a screen drug testing of blood or urine is necessary to confirm the diagnosis. General blood work, electrocardiogram (ECG) monitoring, and chest X-rays are also among the common tests used to rule out other diseases or to identify complications secondary to toxicosis.

Treatment varies according to the specific drug ingested and which symptoms are present.

Treatment might include:

• Inducing emesis (vomiting) if clinical signs are not present, or in cases of recent exposure
• Flushing the stomach
• Administering activated charcoal
• Administering cathartics (laxatives) such as sorbitol -Antagonistic drugs: medications that act in direct opposition to the antidepressants

Note: induction of vomiting and administration of activated charcoal should only be performed by a veterinarian. There is no safe way to induce vomiting or administer activated charcoal at home.

Treatment may also include supportive care such as IV fluid therapy, anti-nausea medications, cage rest, and medication to control seizures.

In mild cases, the prognosis with effective treatment is good to guarded. In more severe cases where seizures or other life-threatening conditions and symptoms develop (such as aspiration pneumonia), the prognosis is guarded to poor, especially if response to treatment is poor.

The condition is not contagious. Prevention includes keeping medications out of dogs’ reach and administering them, when prescribed by a vet, following exactly the correct dosage.

Overall, antidepressant poisoning is moderately common and the number of accidental ingestion or overdose of antidepressants is rising in dogs.

• Activated charcoal
• Flushing the stomach
• Inducing vomiting
• Medications
• Supportive care