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How to Tell Your Dog is Sick: 18 Symptoms of Canine Illness

There are many potential signs that your dog is sick. These range from obvious symptoms, such as vomiting, to more subtle behavioural changes.

To help you recognise when your dog is sick, we’ve put together a list of 18 common symptoms of canine illness. Keep in mind that these are not the only symptoms of illness – there are many more potential signs.

We also want to make it clear that you should always get a veterinary checkup if you notice a potential symptom of illness, behavioural change, or even just get a sense that something isn’t right with your pet. You know your dog best, so you’ll often notice warning signs that aren’t obvious to anyone else.

Don’t delay or take risks with your dog’s health. The sooner your dog gets a proper diagnosis and treatment from a vet, the better the chance of a positive outcome.

Common Signs and Symptoms That Your Dog Is Sick


Occasional vomiting in dogs isn’t unusual. After all, our canine friends love to eat anything they can get their paws on, including things that they shouldn’t!

However, frequent or severe bouts of vomiting can be a symptom of a range of health issues – not to mention being very distressing for your dog. If your dog is vomiting blood, vomits repeatedly, appears lethargic, or you notice a decrease in appetite, it’s time to consult a veterinarian.

Even if your dog isn’t vomiting, it’s important to watch out for signs of nausea. These can include licking the floor (or other objects), restlessness, lip licking, air licking, drooling, or panting.

Some common conditions associated with vomiting or nausea in dogs include gastritis, dietary indiscretion (eating something they shouldn’t have), and pancreatitis. Other serious conditions can include obstructions, poisoning, and certain types of cancers.

Remember, vomiting is a symptom, not an illness in itself. So, veterinary diagnosis is essential for treatment.


Diarrhea is a clear indicator that something isn’t right in your dog’s digestive system.

While diarrhea as a one-off probably isn’t anything to worry about, you should contact a vet if there are more than two episodes, or if the diarrhea is accompanied by other symptoms. Noting the frequency, consistency, and color of the stool can also provide useful information to your veterinarian.

There are many medical issues that could cause diarrhea, including changes in diet, food intolerance, or ingestion of foreign bodies. In some cases, it might be caused by a walk or other activity too soon after eating. More serious causes can be intestinal parasites, infections, inflammatory bowel disease, or even certain cancers.

It’s vital to seek veterinary advice if diarrhea continues, as it can quickly lead to dehydration in dogs.

Unusual Stool

The appearance of your dog’s stool probably isn’t something you want to examine too closely, but it can be an indicator of their overall health. Variations in color, consistency, or the presence of mucus or blood are all potential warning signs. A sudden change in stool consistency, particularly if it becomes watery or very hard, can also be an indication of health problems.

Conditions that might cause changes in your dog’s stool include dietary issues, such as food intolerance or a sudden change in diet, as well as parasitic infections, digestive disorders, or systemic illnesses.

Changes to Urination Frequency

A sudden change in your dog’s urination frequency (more or less) can signal various health issues, so it’s important to get a vet checkup. Straining or discomfort while urinating are also reasons to take your pet to a vet.

Health problems that can cause changes in urination frequency include urinary tract infections, kidney disease, and diabetes. Less commonly, it can also be a sign of liver disease or some types of cancers.

Change in Drinking Habits

Just like changes in urination, differences in your dog’s drinking habits can be a sign of health problems.

An increase in water intake can lead to more frequent urination, and these two symptoms together might indicate conditions such as diabetes or kidney disease. On the other hand, decreased water intake can quickly lead to dehydration, especially in the case of sickness or diarrhea.

It’s important to monitor your dog’s water intake and take note of any changes. Provide clean, fresh water for your dog at all times and ensure they are drinking enough, especially in hot weather. If you’re concerned about your dog’s water intake, consult with your vet.

Related Article: 6 Tips for Keeping Your Dog Hydrated

Loss of Appetite

Loss of appetite

Most dogs love food, so a reduction in appetite is always a cause for concern. If your dog is ignoring their food, is reluctant to take treats, or is eating less than usual, it may be a sign of an underlying health issue.

Appetite loss in dogs can be caused by dental problems, pain, and gastrointestinal issues. There are also more serious systemic illnesses that can cause it, such as cancer or kidney disease. Emotional stress or changes in the environment can also affect a dog’s desire to eat.

You should always contact a vet if you notice a change in your dog’s appetite.

Bad Breath

Bad breath in dogs might seem like a minor issue, but it can sometimes indicate serious health problems.

For example, a foul or unusual-smelling breath could be a sign of dental disease, which can lead to severe complications if untreated. It can even indicate systemic illnesses, such as kidney disease, liver disease, airway infections, gut problems, and diabetes.

So, don’t ignore bad breath or assume it’s normal for a dog. Take them for a vet checkup to rule out serious illness and, if required, get dental treatment.


A healthy dog has a normal body temperature of 101-102.5 degrees Fahrenheit. Any temperature above this range indicates that the dog has a fever, which is a common symptom of illness.

It can sometimes be difficult to spot a fever in dogs, as the only accurate way is to take their temperature. However, if your dog seems lethargic, has a loss of appetite, or is behaving out of character, they may have a fever. Other signs can include shivering, hot ears, coughing, or nasal discharge.

Fever in dogs can be a sign of infection, inflammation, or other systemic illnesses. Some common causes include urinary tract infections, respiratory infections, and ingested toxins.

If you suspect your dog has a fever, it’s important to seek veterinary advice immediately. A fever is an indication that the body is fighting off an illness, and it’s crucial to identify and treat the underlying cause.

Note: There’s a common myth that the temperature of a dog’s nose can indicate whether they have a fever. However, a warm or dry nose could be caused by many things, including a warm environment or recent exercise. It’s not a reliable way of judging if your dog has a fever.

Unexplained Weight Loss or Gain

An unexpected change in your dog’s weight, either loss or gain, could be a sign of several health problems. If your dog is losing weight despite eating normally, or gaining weight without a change in diet or exercise, then you should contact your vet.

Sudden weight loss can be associated with metabolic disorders, dental issues, or serious conditions like cancer. It can also be a sign of chronic stress. Unexplained weight gain might indicate hormonal disorders or other systemic diseases.

Remember, a healthy weight is key to your dog’s overall well-being. Any sudden or unexplained changes should be discussed with your veterinarian. It’s also a good idea to regularly weigh your dog as part of their routine health checks.

Behavioral Changes

Changes in your dog’s behavior are often the first sign that something is wrong. These could include increased anxiety, defensiveness, lethargy, or other alterations in their personality. In some cases, you might just get a feeling that something isn’t right with your pet, even if you can’t explain exactly why.

There is a huge range of health issues that could cause behavioral change in dogs, from neurological disorders to chronic pain. In many cases, these changes may be the first or only signs of a problem.

Don’t ignore behavioral changes in your dog. Always consult with a vet if you think that your pet is acting differently.

Breathing Issues or Coughing

If your dog is coughing frequently, has difficulty breathing, or is panting excessively, it might indicate respiratory problems. These could range from kennel cough and pneumonia, to heart disease or lung problems.

Breathing difficulties can rapidly become serious. If your dog is struggling to breathe, or their breathing sounds unusual, seek immediate veterinary attention. Early diagnosis and treatment of respiratory conditions can significantly improve your dog’s prognosis.

Itchy Skin, Scratching or Hair Loss

Dog hot spot

Scratching or chewing at the skin can indicate a variety of health issues. These include skin allergies, parasites (including fleas), skin infections, or other dermatological conditions. Excessive scratching, licking, or biting can also cause wounds that lead to secondary infections, hot spots, fur colour changes, and other complications.

For these reasons, a vet checkup is essential if your dog seems to be scratching more than normal. Your vet will perform an examination and tests to uncover the underlying cause, which is important for choosing the right treatment.


“Scooting” is when a dog drags its bottom across the ground. While this behaviour can sometimes look amusing, it’s almost always a sign of discomfort or itching. Common causes include issues with the anal glands, worms, or irritation around the tail area.

Scooting isn’t just a symptom of another medical issue – it can also cause damage to the anal area. So, always consult with your vet if you notice your dog performing this behaviour.

Sneezing or Runny Nose

Consistent sneezing or nasal discharge from a dog might be a sign of a health condition. Both can be symptoms of respiratory infections, allergies, nasal mites, or even a foreign object (such as a seed) lodged in the nasal passage.

Always contact a vet if your dog is consistently sneezing or suffering from a runny nose. Potential respiratory issues in dogs need to be assessed as soon as possible.

Important: If the discharge is bloody or pus-like, contact a vet immediately.

Pale Gums

Healthy canine gums should be a pink color. If you notice your dog’s gums are pale or white, it could be a symptom of conditions such as anemia, blood loss, kidney disease, or shock.

Pale gums are often a sign of a serious health problem that requires immediate veterinary care. Don’t hesitate to seek help if you notice this symptom.


Lethargy in dogs can be a symptom of many health issues. So, if your dog is noticeably less active, disinterested in normal activities, or just seems to have no energy, then this could be cause for concern.

Underlying causes of lethargy can include infectious diseases, heart problems, metabolic disorders, or even depression. Keep in mind that lethargy isn’t just a sign of aging or laziness – it’s a warning sign that your dog needs to be assessed by a vet.

Difficulty Walking or Rising

If your dog is struggling to walk, limping, or having difficulty rising from a sitting or lying position, they might have musculoskeletal problems (or another cause of pain). These could include:

  • Arthritis or other joint issues
  • Muscular strains
  • Ligament sprains
  • Tendonitis
  • Wounds
  • Broken bones
  • Neurological disorders

Dogs with musculoskeletal issues might also stop walking on walks, have difficulty getting up staircases, or not want to take part in activities they usually enjoy.

You should always take your dog to a vet if they are struggling with normal movements or seem to be in pain. There are many treatments available to provide relief and improve mobility issues.

Difficulty Settling in One Position

Another sign of pain is that a dog can’t seem to get comfortable. They might pace a lot, constantly change positions, stretch more than normal, or just not be able to sleep. Dogs with abdominal pain may also stretch in the prayer position.

There are many potential causes of pain that can lead to trouble settling. These include gastrointestinal issues, musculoskeletal pain, or nervous system disorders.

Difficulty settling could also be a sign of the life-threatening condition known as “bloat.” This condition is caused by a twisted stomach, and can lead to symptoms such as dribbling, stomach pain, anxiety, stomach distention, and difficulty breathing. Fast treatment is essential if your dog has bloat, which is why you should always contact a vet as an emergency if you notice any of these symptoms.

When to Take Your Dog to a Vet

You should take your dog to the vet immediately if you notice any of the symptoms above. Acting fast can potentially be the difference between successful treatment and a condition that becomes life-threatening.

Additionally, dogs often hide symptoms of illness. So, when they become noticeable, your pet may already be in considerable discomfort. Getting an accurate diagnosis – often with the help of tests and scans – followed by veterinary treatment, is often the only way to help your pet.

Try to keep track of your dog’s symptoms, including when they happen, the severity, and the frequency. Take photos or videos if it might help your vet with the diagnosis, as your pet may not re-produce the limp or other behaviour at the clinic.

Most importantly, don’t take risks with your dog’s health. Your dog can’t tell you that they are unwell or in pain, so you need to treat any symptom as potentially serious until you get a diagnosis from a vet.


Richard Cross

Richard is a journalist who specialises in dog behavior. He's written hundreds of articles and books related to dogs, including for the Continental Kennel Club, Dog Fest (the UK's biggest dog festival) and various veterinary surgeries. When he's not spending time with Jess and Rudy (his beloved Labrador and Golden Retrievers), he enjoys reading, hiking and watching sports.
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