Adams-Stokes Attacks

Adams-Stokes attacks in dogs are sudden fainting spells triggered by severe heart rhythm disturbances, most commonly by complete heart block or extreme bradycardia.

Why are Adams-Stokes attacks relevant for dog owners?

These attacks occur without warning and can be life-threatening. A dog simply collapses, often during normal activity. Many owners mistake this for epilepsy or circulatory problems.

The crucial difference: In Adams-Stokes attacks, the heart stops briefly or beats extremely slowly. The brain receives no oxygen, and unconsciousness follows within seconds.

What happens during an Adams-Stokes attack in a dog?

The attack typically progresses through three phases. First, the sudden collapse; the dog falls sideways, often mid-movement. The mucous membranes become pale to bluish.

This is followed by unconsciousness, usually lasting 10–30 seconds. The pulse is not palpable or extremely weak. Some dogs show convulsive twitching; this is the brain’s reaction to oxygen deprivation.

Recovery usually occurs quickly. The heart regains its rhythm, the mucous membranes turn pink, and the dog stands up. Many dogs appear completely normal afterwards, as if nothing had happened.

How do Adams-Stokes attacks differ from epilepsy?

In epilepsy, the attack usually begins with restlessness or disorientation. The dog drools excessively, paddles with its legs, and may lose control of faeces or urine. After the attack, it is often confused and needs time to reorient itself.

Adams-Stokes attacks are different: The collapse comes without warning. No drooling, no paddling. Recovery is abrupt; the dog is immediately back to normal.

Which breeds are more frequently affected?

Larger breeds with a predisposition to cardiomyopathy carry a higher risk. Dobermans, Great Danes, Boxers, and Irish Wolfhounds more frequently develop the heart conditions that can lead to Adams-Stokes attacks.

However, small breeds are also affected, particularly older dogs with degenerative heart changes. Age alone is not, however, a trigger.

What to do if the dog has an Adams-Stokes attack?

Stay calm and place the dog on its side if it is not already lying down. Slightly extend the head to keep the airways clear. Do not put anything into the mouth.

Start timing: If unconsciousness lasts longer than one minute, go to the vet immediately. Even with shorter attacks, a timely vet examination is necessary.

Document the attack: time, duration, circumstances. This information helps the vet with the diagnosis.

How is the diagnosis made?

The vet performs an ECG, often also a long-term ECG over 24 hours. Blood tests and usually an echocardiogram to assess heart structure are added.

The challenge: Adams-Stokes attacks occur unpredictably. The ECG in the practice may show no abnormalities. Therefore, the precise description of the attack is so important.

What treatment options are available?

If the diagnosis is confirmed, a pacemaker is usually recommended. These devices are now also available for dogs and can significantly extend life.

Pharmacological alternatives are limited and usually less successful. In mild cases, antiarrhythmics can be tried, but they do not address the underlying cause.

What is the prognosis?

Without treatment, Adams-Stokes attacks are life-threatening. With a pacemaker, the prognosis is good; many dogs live normally for years afterwards.

The decision depends on age, general condition, and the dog owner’s wishes. A pacemaker is a major intervention with corresponding costs.