What this means
Owners describe a collapse in different ways: the dog switched off, crumpled, tipped to the side, dragged its back legs or simply could not stand. It helps to write down what your dog was doing at the time: playing, running, excited, eating, resting or lying down. Also how long it lasted and how your dog looked afterwards.
A collapse differs from a seizure in that the dog is usually limp rather than paddling its legs and clenching its jaws, though the two are not always easy to tell apart. A video, if it can be taken safely, helps a lot. Also note the gum colour: pale or bluish gums show that the body is not getting enough oxygen or blood.
The causes include the heart, blood sugar, hormones and inborn or inherited problems. Some breeds, such as retrievers, can collapse after intense exercise or excitement, and young larger dogs can have an inborn heart defect. The cause is found by a vet, often after heart and blood tests.
Possible causes
These are things that can cause this sign. It is not a diagnosis, and they are not equally likely for your dog.
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Exercise-induced collapse
In some breeds, especially retrievers, the hind legs weaken after hard exercise or excitement and the dog goes down. The dog usually recovers within a few minutes.
About the condition: Exercise-induced collapse -
Heart disease and rhythm disturbances
When the heart suddenly fails to push out enough blood, the brain receives too little. A collapse can come during exertion or for no obvious reason.
About the condition: Heart disease -
Low blood sugar
When the blood lacks sugar, a dog grows weak, wobbly and may go down. Small puppies and dogs of small breeds are especially vulnerable.
About the condition: Hypoglycemia (low blood sugar) -
A shortage of adrenal hormones
This disorder can cause sudden weakness and collapse, especially under stress. Sometimes lethargy, vomiting or loose stools are seen on several occasions beforehand.
About the condition: Addison's disease -
An inborn narrowing in the heart outflow
A narrowed spot in the left ventricle makes it harder to push blood out. It is mostly found in young, larger dogs, and a vet often hears a heart murmur.
About the condition: Subaortic stenosis -
Internal bleeding or overheating
Blood loss inside the body or overheating can cause sudden weakness. The dog has very pale gums or pants hard.
What else to watch for
These observations help your vet build the picture faster. Note down what you saw and when.
- What your dog was doing before the collapse and how long it lasted
- Whether it has happened again and in what circumstances
- What colour the gums were
- Whether your dog was breathing hard or fast
- Whether there was earlier coughing, quick tiring or lethargy
- How quickly and how completely your dog recovered
When to book a routine visit
Even if your dog has recovered and seems normal, contact a vet the same or the next day, because the reason for the collapse is still unknown. If your dog is still weak, struggling to breathe or the collapse is repeating, go straight away.
Related conditions
Conditions whose entries mention this sign. The list is somewhere to read on, not a way to reach a diagnosis.
- Exercise-induced collapse Nerves and muscles Exercise-induced collapse is an inherited disorder in which, after intense and exciting exercise, a dog's hind legs suddenly weaken and it can no longer walk. Between episodes the dog seems completely healthy and it recovers after rest. A genetic test exists, so breeders can screen their breeding dogs.
- Heart disease Heart This is an umbrella term for various conditions in which the heart muscle, the valves or the heart rhythm stop working as well, making it harder for the heart to pump blood around the body. Some are present from birth, others develop with age, and they can go a long time without any noticeable signs. During a check-up the vet listens to the heart and decides whether further tests are needed.
- Hypoglycemia (low blood sugar) Hormones and metabolism Hypoglycemia is a condition in which the level of glucose in the blood drops too low and the brain and muscles run short of energy. It can affect young puppies and small dogs, especially if they have gone a long time without food or are exhausted, as well as dogs with certain diseases. Hypoglycemia can quickly become life-threatening, so the dog needs a vet immediately.
- Addison's disease Hormones and metabolism Addison's disease is a condition in which the adrenal glands make too little of certain hormones that help the body cope with stress and keep its balance of salts and water. Its signs are vague and can come and go, so it is easy to miss. The condition can, however, suddenly worsen and become life-threatening, and then the dog needs a vet immediately.
- Subaortic stenosis Heart Subaortic stenosis is a congenital heart defect in which tissue just below the aortic valve narrows the path blood takes from the left ventricle into the aorta. To push blood through the narrowing the heart has to work harder, and its muscle thickens over time. The defect ranges from barely noticeable to severe, so how much it has affected the heart is for a vet to assess.
Body systems: Nerves and muscles Heart Hormones and metabolism