Fainting in dogs is when they suddenly lose consciousness or ‘black out’ for a short while. Most dogs recover quickly and return to normal within a few minutes. However, fainting can result from serious underlying health conditions. Seek urgent veterinary help if your dog faints.

The medical name for fainting in dogs is syncope. It happens when there isn’t enough blood getting to the brain. When dogs faint they lose consciousness suddenly and fall limply to the ground. This is different to seizures, where your dog is more likely to be rigid or have jerking limb movements. There are different underlying causes for fainting in dogs. Not all are life-threatening, but prompt investigation is essential. Treatment and long term outlook depend on the reason for fainting.

What to do

What to do if your dog faints

• Try to position your dog with their head down and their hind quarters raised. This will help to improve blood flow to the brain.
• Cover your dog with a blanket to keep them warm.
• If your dog vomits, make sure their head is down and mouth clear so they don’t inhale vomit into their lungs.
• Try to record the episode on your phone.
• Seek urgent veterinary help.

Things not to do if your dog faints:

• Don’t try to give anything by mouth. If your dog is unconscious whatever you give them may end up in their lungs.
• Do not try to give your dog a shock to wake them, like slapping them or dousing them with cold water.
• Don’t assume everything is ok just because your dog recovers quickly and seems back to normal. There can be serious underlying causes of fainting.

Always seek veterinary help if your dog has a fainting episode, however brief.

Causes

What are the common causes of fainting in dogs?

Syncope or fainting is a symptom, with more than one possible cause. Some of these causes are life-threatening. Urgent veterinary investigation is essential.

• Heart-related causes: irregular heart beat, congestive heart failure, weakening of heart muscle or a slow heart rate may lead to reduced blood flow to the brain and result in fainting.
• Breathing problems: Coughing or difficulty breathing due to pneumonia or bronchitis, BOAS or tracheal collapse. These illnesses reduce the oxygen getting into the blood and the brain and result in fainting.
• Brain or nervous system abnormalities, such as seizures or tumours can cause vagal collapse, also called vasovagal syncope. This causes a sudden drop in blood pressure and can result in fainting. It can be triggered by extreme emotion like stress or excitement, such as seeing you, a favourite toy or hearing the doorbell.
• Metabolic illnesses: Fainting happens because of low sugar (Diabetes) or low sodium (Addisons). 
• Exercise or exhaustion: Exercise-induced collapse affects certain breeds, including Labradors and Border Collies. Brachycephalics can overheat easily and collapse.
• Heat stroke
• Adverse reaction to medication, especially blood pressure medicine

 

When to worry

When to worry about fainting in dogs

Find your nearest vet if your dog is:

• Fainting multiple times
• Taking longer than a minute to recover
• Showing other symptoms: blue or pale gums, breathing problems, severe vomiting and diarrhoea.

Joii can help with:

• Recognising the signs of seizures and fainting
• How to give medicine to dogs
• Understanding illnesses that cause fainting
• Choosing the best diet for your dog

Prevention

How to reduce the risk of fainting in dogs

Until we know what is causing fainting, prevention will be challenging.

General options and specific measures to reduce risk include:

• Avoid recognised triggers: Triggers may include overexercising, overstimulation, overexcitement, stress
• Use a harness in place of a collar and lead.
• Treat other illnesses effectively: Give all prescribed medicine as directed by your vet.
• Feed and exercise your dog according to their age, lifestyle, breed and general health.
• Keep your dog slim, with a good body condition score.

Diagnosis

How do vets diagnose the cause of fainting in dogs?

When your dog collapses it can help to differentiate between a faint and a seizure:

Factors suggesting fainting :

• Short duration, with full recovery in less than a minute
• Floppy sudden collapse
• May start with weakness, staggering, disorientation, vomiting or diarrhoea
• More likely to be triggered by exercise or stress

Factors suggesting a seizure:

• More likely to be disoriented and slow to return to consciousness
• More rigid limbs, possible twitching, jerking
• Often happen at rest or without any recognisable trigger

Once you and your vet have discussed the symptoms, further tests may include one or more of the following:

• Blood tests
• Urine analysis
• ECG: to measure electrical impulses in the heart. Holter monitor is a wearable device that records the ECG over a number of days.
• Imaging: x-rays, ultrasound, heart scan
• Advanced imaging: CT or MRI

Home treatment

How to care at home for a dog experiencing fainting episodes

• Give all medicines prescribed by a vet at the correct time and dose
• Feed your dog appropriately as your vet may advise a special prescription diet
• Give your dog a peaceful and quiet place to rest
• Manage your dog’s exercise carefully and ask your vet for advice
• Remove or avoid known triggers likely to cause further fainting episodes

Vet treatment

What’s the treatment for fainting in dogs?

Treatment for fainting episodes depends on the underlying cause. Possibilities include:

Prescription Medication:

• Controlling blood pressure
• Improving circulation
• Controlling heart rate and rhythm
• Treating diabetes and other implicated illnesses
• Improving airway function
• Treating seizures

Surgery:

• Helping brachycephalic dogs to breathe more easily
• Reducing pressure on the heart and lungs or correcting blood vessel abnormalities

Other procedures:

Cardiac catheterisation: Advanced technique to access the heart for certain diagnostic and treatment procedures. It involves passing a fine wire or tube from a vein in your dog’s neck or groin all the way to the heart. Procedures include:

• Fitting a pacemaker: to control heart rhythm and rate
• Heart Ablation: a procedure that is done to inactivate the part of the heart causing an irregular fast heart beat.

Risk

Which dogs are at most risk of fainting?

Factors which increase your dog’s risk of fainting include:

• Belonging to certain breeds: Brachycephalic breeds due to their facial shape and being prone to overheating; Labradors and Border Collies inherited disorders that can cause fainting.
• Having heart disease and irregular heartbeat: Cocker spaniels, Miniature Schnauzers, Pugs, and Dachshunds, Boxers, German Shepherds.
• Having other illnesses: diabetes, kidney disease, gastroenteritis, Addisons, liver disease, brain disorders, certain cancers
• Being older

What else can look like fainting in dogs?

Other conditions which may cause dogs to fall to the ground an/or lose consciousness include:

• Seizures: loss of consciousness, but stiff or jerking limbs rather than limp.
• Severe Arthritis: falling or unable to stand, but won’t lose consciousness
• Muscle weakness: may fall to the ground, but won’t lose consciousness
• Vestibular disease: staggering and falling, but confused or dazed rather than unaware.
• Stroke: Fainting may result from a stroke. Other symptoms are also usually present.

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