Ask a Vet: What Causes Panting and Trembling in Senior Dogs?

I love old dogs. I love their wizened, grey muzzles. I love their peaceful, cloudy eyes. I love that most have acquired a certain wisdom and mellowness. They have seen a lot in their lives, and their feathers usually aren’t easy to ruffle.

Many things change in dogs as they grow old. The lenses of their eyes develop a blue, cloudy tint. This normal phenomenon, called nuclear sclerosis, is harmless and does not compromise their quality of life. Many dogs develop arthritis, and their gait may become stiffer (owners of elderly dogs should discuss with their vets options to improve mobility). The hearing of old dogs is not as keen as it once was. Elderly dogs also may need to empty their bladder more frequently than younger counterparts (and they may therefore be more prone to accidents in the house). Old dogs tend to sleep more heavily.

Although the changes in the eyes sometimes alarm owners of old dogs, most of the others don’t usually cause much distress. They happen in people, too, and they’re considered a normal part of aging.

Senior Boxer by Shutterstock.

However, two additional common changes often do cause consternation. Old dogs tend to pant more than young dogs. They also are prone to trembling. Over the years, many people have asked me why these two things happen.

There is no simple answer. Panting and trembling are two of the least specific symptoms a dog might exhibit. Anything that might cause a person to sweat or tremble might cause a dog to pant or tremble.

In the case of panting, there is a common and I’m happy to say generally benign cluster of factors that may cause the behavior. As dogs age, the diaphragm and intercostal muscles, which are used to breathe, become weaker. Elderly dogs may also be prone to additional adipose deposits (which is a fancy way of saying they may be fatter) in their abdomen and on the body wall. As a result, they may sometimes find it easier to pant, which involves less use of the diaphragm and muscles in the chest because breaths taken while panting tend to be shallow. Those shallow breaths also encounter less of the resistance on the diaphragm that is caused by abdominal fat.

Trembling, too, may have relatively benign causes. Surely you have noticed that elderly people often tremble — the hands and mouth may be the most common sites for trembling in senior citizens. In dogs, a similar type of trembling (which most often affects the limbs and jaws) may occur. It appears to be linked to weakening of muscles with age, along with mild degeneration of the nervous system.

Older dogs seem to be more reactive to excitement and adrenaline. Therefore, when an exciting or fearful situation presents itself, the stimulation of the event may collaborate with the above factors to trigger or exacerbate panting and trembling.

If your older dog is panting or trembling more, you can take some solace from these facts. However, you should not become complacent. In some instances, both panting and trembling may be signs of a more serious problem.

Senior dog by Shutterstock.

Obesity, unfortunately, is common in older dogs. Although the panting caused by obesity isn’t harmful on its own, being significantly overweight can lead to many other more serious issues. It can exacerbate arthritis and mobility concerns, as well as heart disease and other respiratory ailments.

Pain may cause both panting and trembling. An older dog who pants more may be suffering from back pain or arthritis pain that is impacting his quality of life.

Heart disease and breathing problems such as chronic bronchitis, collapsing trachea, and laryngeal paralysis may lead to panting. Glandular conditions such as Cushing’s disease may cause panting as well. Certain metabolic conditions also may cause both panting and trembling. Brain disease may cause panting and trembling.

Sudden onset of panting may be a sign of a very serious problem. Panting is a common — and sometimes the only — symptom of gastric dilatation with volvulus, also known as GDV and bloat. This condition, which is most common in older, large dogs, is an emergency of the highest order, and it can cause death in hours if not treated appropriately.

Finally, cognitive decline should be considered as a cause of panting in elderly dogs. Panting caused by dementia may occur primarily at night and may be accompanied by restlessness and movement of the dog to atypical areas of the home. However, if your dog suddenly starts exhibiting these behaviors, remember that bloat also occurs most often at night and may trigger restlessness.

Although much of the panting and trembling done by older dogs has a benign cause, there is no guarantee that such behaviors in an elderly dog are harmless. Any owner of an elderly dog who pants or trembles should have a vet evaluate his pet.

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