Why does my dog shake – does he have epilepsy?


“OMG … I think my dog is having a seizure!” Cue the fog of clear thinking that is often the result of hysteria and alarm.

The onset of uncontrolled “shaking” can be very alarming. In those initial seconds and minutes of anxiety and panic, rarely do owners take the time to properly observe the characteristics of the event unfolding in front of them. Later recalling the experience to a vet, the recollection can be generic and often vague.

Why is this important, shaking is shaking? I hear you ask.

Shaking is never just shaking. It is rather a broad term that can easily over-simplify a far more complex range of conditions. The first distinction we should try and make is whether it is tremors or seizures. This is important as the possible causes, diagnosis and treatment differs between the two. 

What is the difference between tremors and seizures?

Unfortunately, it is sometimes difficult to differentiate tremors from seizures as both involve abnormal muscle contractions. 

Tremors are involuntary muscle movements occurring while the dog is awake. During episodes the dog remains aware of its surroundings and does not lose consciousness.  

Seizures on the other hand are subcategorised into 2 types:

1. Generalised seizures

Typically dogs with generalised seizures will fall onto their side, will become stiff and paddle all four limbs. They usually become unconscious and may pass urine/faeces, salivate excessively or vomit. These are known as generalised or grand mal seizures. 

2. Partial seizures

Some dogs exhibit partial/focal seizures, meaning that rather than the whole body being affected, only a single limb or possibly only the face may be affected by abnormal movement (e.g. lip smacking, fly catching). They may or may not lose consciousness, meaning that it may be difficult to differentiate these seizures from tremors. 

Some dogs may show behaviour changes prior to a seizure, for example becoming quieter, anxious, hiding, pass urine/faeces etc. We call these pre-ictal signs. Typically, dogs will exhibit behaviours after a seizure such as unsteadiness on their feet, quieter demeanour etc that may last from minutes to hours. We call these post-ictal signs. 

What can cause tremors?

There are numerous possible causes of tremors. These include:

1. Small dog trembling 

For some small breed dogs (for example Chihuahuas and Yorkshire Terriers), episodes of shaking can be normal. For many there is no obvious underlying cause or evidence of associated illness and no need for treatment. (However, if it starts suddenly, it’s always best to rule out more serious issues before assuming that this is the cause – Ed.)

2. Excitement/fear/anxiety 

Some dogs show significant shaking associated with excitement or due to stress and anxiety.

3. Hypothermia 

Dogs will shake if they are cold or wet for extended periods of time.

4. Pain 

Shaking may be an indication that dogs are painful. Importantly, not all dogs who are uncomfortable will shake.

5. Muscle weakness 

Muscle weakness in the hind limbs is not uncommon in dogs, especially as they get older. This can result in trembling of the hind limbs, particularly as they get up from rest.

6. Underlying medical conditions 

Blood changes including low blood sugar, low blood calcium (sometimes observed in pregnant dogs) or electrolyte abnormalities can cause trembling/shaking.

7. Generalised Tremor Syndrome (also known as Little White Shaker Syndrome or Steroid Responsive Tremors) 

This condition typically affects small breed white dogs (e.g. Maltese and West Highland White Terrier). Affected dogs show repetitive involuntary muscle contractions that affect the entire body or are localised to a particular area (for example a limb or the head) from approximately 1-2 years of age. It typically occurs with exercise but dogs are normal between episodes. This syndrome responds well to treatment with steroids, with a significant improvement usually noted within 1-2 weeks. 

8. Movement disorders 

Intermittent episodes of abnormal movements occurring as attacks with no loss of consciousness. Different movements are noted, but most commonly these involve the hind limbs and can be sufficient to prevent the dog from walking. Attacks can last anywhere from a few minutes to hours and may be triggered by excitement or exercise. It is often difficult to differentiate these from partial seizures.

What can cause seizures?

There are a number of different causes of seizures in dogs. These include:

1. Idiopathic epilepsy 

This is the most common type of seizures seen in dogs and will typically start between 6 months and 6 years of age. After diagnostic testing such as bloods and MRI scanning of the brain, no underlying cause is found. They can occur in any breed but are more frequently observed in certain breeds e.g. Border Collies. Epileptic seizures can occur with varying frequency and for some animals their control with anti-seizure medications is required.

2. Trauma 

Any head injury can result in seizures.

3. Toxicity 

Ingestion of certain toxins can cause sudden onset seizures in previously healthy dogs. These include but are not limited to slug bait, chocolate and xylitol (sugar alternative in chewing gum).

4. Issues with your dog’s bloods or organ function 

Things such as low blood sugar (for example in diabetic dogs given excessive insulin, or puppies who have not eaten for a while) can result in seizures occurring. Dogs with liver function problems can fail to effectively filter toxins from the blood stream which can result in seizures. This can be due to developmental issues (e.g. portosystemic shunts) in younger dogs, or severe liver disease in older dogs. 

5. Brain tumour 

Brain tumours are an uncommon cause of seizures, but are more commonly seen in older dogs.

6. Infection and inflammation of the nervous system 

Certain infections/inflammatory conditions (e.g. meningitis) affecting the central nervous system and the brain can cause seizures.

What should I do if my dog has a seizure?

If your dog shows any abnormal shaking, try not to panic. Try to seek prompt medical attention from your veterinary surgeon even if the shaking stops before you visit the vet. Untreated seizures lasting more than 5 minutes or seizures occurring one after the other (known as clustering) can result in permanent brain damage or even death.

If possible, video and time the duration of the episode as this will help your vet differentiate between seizures and tremors.

Prior to taking them to the vets, keep calm and quiet, turn off the lights and move away any furniture that they could hit themselves on. Providing your dog is safe in the environment they are in, it is best avoiding direct contact with your pet as owners are at risk of being bitten whilst the dog is unaware of its behaviour. The exception to this is if you are having to move your pet to the vet as the seizure is not stopping. If you are in this situation take extreme care. Where possible contact the veterinary clinic and make them aware of your intended arrival so the appropriate equipment and medications can be prepped in advance.

What is the treatment?

Your vet will perform a full clinical exam and take a full history. In most cases bloods will be advised and further testing (referral to a neurologist/MRI scan) may be recommended. 

Depending on the cause, different treatments may be recommended. These treatments may include the use of a variety of anti-seizure medications which for some dogs may need to continue long-term. Your vet will be best placed to advise you on all the specifics for your dog’s individual situation.

Summary

The difficulty in describing and differentiating these events is why videoing the episode of “shaking” is perhaps the single most useful thing an owner can do prior to coming to the vet clinic. A video really does paint 1,000,000 words.

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