A dog that’s shaking with its tongue out is usually either overheated, in pain, stressed, or experiencing a medical emergency. In many cases, both signs together point to your dog’s body working hard to cool down or cope with physical distress. The combination can be perfectly harmless, like after a long play session, or it can signal something serious like poisoning, a seizure, or dangerously low blood sugar. What matters most is context: what your dog was doing before this started, how long it’s been going on, and whether other symptoms are present.
Overheating and Heat Exhaustion
The most common and least alarming explanation is that your dog is simply hot. Dogs can’t sweat through their skin the way humans do. Instead, they pant to pull large volumes of air across the moist surfaces inside their nose and mouth, which evaporates moisture and lowers body temperature. The tongue hangs out to increase that evaporative surface area, and the body also ramps up saliva production to help the process along. If your dog has been exercising, lying in the sun, or stuck in a warm room, panting with the tongue out and mild body trembling is the cooling system doing its job.
The concern is when cooling can’t keep up. Heatstroke in dogs begins when core body temperature rises above 105.8°F (41°C), and it progresses fast. At that point, the heat starts directly damaging tissues, especially in the brain. Signs that your dog has crossed from “warm” to “in danger” include heavy, frantic panting that doesn’t slow down, drooling thick or ropy saliva, stumbling or confusion, vomiting, and gums that look bright red or turn pale. Flat-faced breeds like bulldogs and pugs are especially vulnerable because their shorter airways make panting less efficient. If you suspect heatstroke, move your dog to a cool area and offer water, but don’t use ice-cold water, which can cause blood vessels to constrict and trap heat inside the body.
Pain or Physical Distress
Dogs in significant pain often tremble and pant simultaneously. Pain activates the body’s stress response, flooding the system with adrenaline. That surge raises the heart rate, speeds up breathing, and can cause visible shaking, especially in the legs and core. The tongue comes out because the faster breathing rate naturally leads to open-mouth panting.
The tricky part is that dogs are often stoic about pain. They may not whimper or cry. Instead, look for subtler clues: reluctance to move or stand, flinching when you touch a specific area, a hunched posture, or a sudden change in temperament like snapping when approached. A resting breathing rate above 40 breaths per minute, when your dog hasn’t been exercising, is another signal that something is off. Common causes of acute pain include gastrointestinal distress (bloating, obstruction), injuries that aren’t externally visible like a pulled muscle or spinal issue, and internal conditions like pancreatitis.
Poisoning or Toxic Exposure
If shaking and tongue-out panting came on suddenly and your dog had access to something they shouldn’t have eaten, poisoning is a real possibility. Muscle tremors combined with excessive drooling are classic signs that a toxin is affecting the nervous system. Chocolate and caffeine cause hyperactivity, a racing heart rate, tremors, and in severe cases, seizures. Xylitol, a sweetener found in sugar-free gum and some peanut butters, causes a dangerous crash in blood sugar that leads to trembling and weakness within 30 minutes of ingestion. Grapes, raisins, and onions are also toxic to dogs.
Other warning signs of poisoning include confusion, difficulty walking, vomiting, diarrhea, and collapse. If you notice any combination of these alongside shaking, try to identify what your dog may have gotten into and contact a veterinarian or pet poison hotline immediately. Time matters with poisoning, and knowing what your dog ate helps determine the right treatment.
Low Blood Sugar
Hypoglycemia, or low blood sugar, causes trembling because the muscles and brain aren’t getting enough fuel to function normally. Dogs typically don’t show symptoms until blood glucose drops below 40 to 50 mg/dL, well below the normal range. When it does, you’ll see shaking, weakness, disorientation, and sometimes the tongue hanging out loosely as muscle control slips.
Small breeds and puppies are most at risk because they have less stored energy to draw on. Toy breeds that skip a meal or burn through their reserves during a long play session can crash quickly. Dogs with diabetes who receive too much insulin are also vulnerable. If your small dog is trembling and seems “out of it,” rubbing a small amount of honey or sugar water on their gums can help in the short term while you get to a vet.
Seizures and Neurological Causes
Not all seizures look like the dramatic full-body convulsions most people picture. Focal seizures can affect just one part of the body or show up as repetitive, involuntary movements like lip-smacking, chewing at the air, excessive licking, or rhythmic swallowing. A dog experiencing a focal seizure may drool heavily, seem “zoned out” or unaware of their surroundings, and tremble in isolated muscle groups. These episodes often have a clear start and stop, lasting seconds to a few minutes, and tend to happen during rest or while the dog is falling asleep.
Idiopathic generalized tremor syndrome, sometimes called “white dog shaker syndrome,” is another neurological cause. It’s an immune-mediated condition that typically appears in young dogs, with onset most commonly between 9 months and 2 years of age. Despite the name, it affects dogs of all colors and breeds. In a large study of 198 dogs with generalized tremors, the most commonly affected were mixed breeds, Labrador retrievers, Jack Russell terriers, and West Highland White terriers. The tremors are usually full-body, worsen with excitement or activity, and improve with rest. This condition responds well to treatment and isn’t painful, but it does need a veterinary diagnosis to rule out other causes.
Stress, Fear, and Anxiety
Emotional distress is easy to overlook as a cause of shaking and panting. Thunderstorms, fireworks, car rides, vet visits, or even a new person in the house can trigger a fear response that looks identical to physical illness: trembling muscles, rapid breathing with the tongue out, pacing, and sometimes drooling. The key difference is context. If the shaking started when the storm rolled in and stops when it passes, anxiety is the likely explanation.
Some dogs develop generalized anxiety that causes these episodes more frequently. Panting and trembling that consistently appear during specific situations, like being left alone or encountering loud noises, point toward a behavioral pattern rather than a medical one.
Red Flags That Need Immediate Attention
Shaking with the tongue out can be benign, but certain additional signs turn it into an emergency. Check your dog’s gums: healthy gums are pink and moist. Gums that appear white, blue, grey, or purple indicate poor oxygen circulation or shock and require immediate veterinary care. Other emergency signs include:
- Unresponsiveness or disorientation that doesn’t resolve within a few minutes
- Abdominal bloating or swelling, especially with retching that produces nothing
- Repeated vomiting or bloody diarrhea
- Seizure activity lasting more than two to three minutes, or multiple seizures in a row
- Sudden inability to walk or rear-leg weakness
- Known ingestion of a toxic substance
If your dog is shaking and panting but is otherwise alert, responsive, eating normally, and the episode passes within a reasonable time after cooling down or calming down, it’s likely nothing dangerous. But shaking that persists for more than 30 minutes without an obvious cause, gets progressively worse, or comes with any of the red flags above warrants a call to your vet. When in doubt, a short video of the episode can be incredibly helpful for your veterinarian to review, since these symptoms often resolve by the time you arrive at the clinic.