What this means
Dogs dream, so a short burst of quick breathing with twitching paws or a quiet squeak is normal. It is different when the breathing stays fast throughout the sleep and your dog seems deeply asleep. A quiet night or a rest is one of the best chances to notice a change in breathing, because your dog is neither running, nor excited, nor overheated.
Watch for yourself: while your dog is sleeping calmly, look at the sides and belly and count the breathing movements over a minute, for instance with a clock. Write the number down and do it for several days in a row so a trend shows. Add notes on whether the room was warm, whether your dog had just been active, and whether it breathes through the nose or with the mouth open. A vet values notes like these more than a one-off impression.
It is important to tell fast breathing from laboured breathing. If your dog moves its belly strongly with every breath, stretches out its neck, cannot lie down comfortably or keeps shifting about without settling, that is already urgent. Breathing that slowly gets quicker over several days is also worth discussing, even if your dog otherwise seems bright.
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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Heart disease and fluid in the lungs
When the heart cannot keep up with the load, fluid can build up in the lungs and breathing speeds up even at rest. This is one reason vets ask owners to watch a sleeping dog.
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A leaking heart valve
When a valve no longer closes tightly the heart has to work harder. Faster breathing at rest can be one of the first changes anyone notices.
About the condition: Mitral valve disease -
A valve that formed abnormally from birth
In some puppies a valve develops abnormally. It can show as fast breathing, tiring quickly or poorer growth.
About the condition: Mitral valve dysplasia -
A weakened heart muscle
When the heart muscle stretches and pumps more weakly, breathing may speed up and your dog may tire sooner. It is seen more often in older dogs of large breeds.
About the condition: Dilated cardiomyopathy -
A blood vessel from birth that should have closed
If a vessel from before birth does not close afterwards, the lungs receive too much blood. A puppy may breathe faster and grow more slowly.
About the condition: Patent ductus arteriosus (PDA) -
Lung or airway disease
Inflammation of the lungs, fluid in the chest or narrowed airways can also speed up breathing during sleep. Your vet will work out the exact cause.
What else to watch for
These observations help your vet build the picture faster. Note down what you saw and when.
- How many breaths per minute your dog takes while calmly asleep, written down over several days
- Whether the breathing is slowly getting quicker
- Whether the belly or sides work hard with each breath
- Whether your dog breathes with the mouth open or noisily
- Whether it coughs, especially at night or when lying down
- Whether it tires sooner on walks or plays less
When to book a routine visit
If your dog regularly breathes fast while asleep, write it down and tell your vet; this is something a vet wants to know about even if your dog otherwise seems well. If breathing is laboured, 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.
- 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.
- Mitral valve disease Heart The mitral valve separates the left upper and lower chambers of the heart, and in this disease its leaflets gradually thicken and stop closing tightly. As a result, some blood flows backwards with every beat, the heart has to work harder and over time it enlarges. The disease develops slowly with age, and a vet may hear a heart murmur long before an owner notices any change.
- Mitral valve dysplasia Heart Mitral valve dysplasia is a heart defect present from birth, in which the valve between the left atrium and the left ventricle, its leaflets or the cords that hold them are malformed. Such a valve may leak or narrow the path for blood, so the heart has to work harder and may enlarge over time. The defect ranges from mild to severe, so how much it has affected the heart is for a vet to assess.
- Dilated cardiomyopathy Heart Dilated cardiomyopathy is a disease of the heart muscle in which the muscle becomes thin and weak and the heart chambers stretch and enlarge. Such a heart contracts less forcefully and can no longer pump blood efficiently, so the heart rhythm can become irregular and fluid starts to build up in the body. The disease can progress unnoticed for a long time while the heart is still able to cope with the growing strain.
- Patent ductus arteriosus (PDA) Heart Before birth, blood bypasses the lungs through a small vessel called the ductus arteriosus, which should close shortly after birth. If it stays open, some of the blood flows where it shouldn't, so the heart has to work harder and is gradually worn down. It is a congenital heart defect that a vet may hear as a distinctive heart murmur when examining a puppy.
Body systems: Heart