When a dog is panting and shaking it's generally safe to assume that something is wrong. But it's often not easy to tell whether it's due to something simple (such as being too hot or too cold) or something more serious (such as illness, pain or injury).
The clues to what's going on can usually be found by assessing your dog's physical condition, the situation he's in, and any other symptoms that he may be showing.
Let's start with the panting part of the equation because it can be caused by so many different things, some serious, some not.
Sometimes it's easy to see why it's happening.... for example, if your dog has just played a vigorous game of fetch; been outside on a hot day; is feeling car-sick; is scared of July 4th fireworks or he's in a situation that is making him nervous, then heavy panting is to be expected.
At other times it's caused by something you can't see, or are unaware of. All of these things can cause your dog to pant heavily:
Obviously some of them aren't medical emergencies, but some of them are.
If your dog is just shaking, shivering or trembling, that opens up another range of other possibilities.
Shaking by itself can still indicate nausea, excitement, fear, anxiety, pain or stress.
It's also common in older and elderly dogs due to age-related muscle weakness, this is normal and although a vet visit is in order to check it out, it's not an emergency.
But shaking in dogs can also be caused by other conditions such as:
If you're familiar with the cause of your dogs panting/shaking (eg. he's always terrified on July 4th, or when he rides in a car etc.) and you know his life isn't in danger then you have options in terms of treating the problem.
Treating stress/anxiety with natural methods can be very effective without the side effects of drugs.
Giving your dog a safe spot to get away, or hide, such as a covered crate or corner in a darkened room can also help.
Car travel can make some dogs anxious as well as nauseous and cause shaking, panting, drooling and more. There are ways to desensitize your dog and to relieve his nausea and fear. Check out my Dog Travel Anxiety page for lots of tips and suggestions.
Low blood sugar, aka Hypoglycemia, which is most often seen in small and tiny breeds, CAN be serious, if not recognized and treated promptly. It can cause a dog to be shaky, wobbly and to pant.
Not eating frequently enough is the most common cause of hypoglycemia in small dogs who need to eat much more often than medium and large breeds.
The best thing to do if you notice signs of low blood sugar in your dog is to rub a little honey, maple syrup or Karo syrup onto his gums and/or put it under his tongue. Keep him warm. rested and encourage him to drink. If you don't see almost immediate improvement, take him to your veterinarian as either something else is wrong, or he needs more help than you can give at home.