Dogs can't express to their owners that they are sick but they wouldn't even if they could. Wild animals are hard-wired to hide pain, injury, and illness to protect themselves from predators when they are in a weakened state. Although they have been domesticated for thousands of years, dogs still have this behavioral trait. It makes it difficult to determine if your dog is in pain, especially since canines are so loyal and loving that they have been known to jump up and greet their humans, even with fractured bones and other injuries.

Changes in Energy Levels & Sleep Patterns

Dogs are creatures of habit that often develop observable routines which can give clues related to their well-being. Take notice of when your dog is active or at rest and be watchful for changes in those patterns. If your dog appears lethargic, it could say a viral, parasitic, or bacterial infection as well as anemia, injury, poisoning, or reaction to the medication. If your dog appears to have trouble getting a comfortable sleep, seems restless during normal sleep times, or gets up more often in the night, it could be a sign of pain and discomfort. Also, sleeping more than usual could mean your dog has a serious medical issue such as hypothyroidism, kidney disease, diabetes, arthritis, or heart issues.

Gastrointestinal Disturbance

One of the most obvious and disagreeable signs of sickness in your dog is the development of a gastrointestinal issue. Gastrointestinal disturbances come in a variety of forms including:

• Vomiting. If vomiting occurs several times, blood is noted in it or we stop eating, this is a concern.
• Diarrhea. There are many simple or serious causes of canine diarrhea. If your dog's diarrhea continues for an extended period or is coupled with other symptoms, the cause may be a serious health issue.
• Loss of Appetite. Decreased interest in food, unrelated to hot weather or advancing age, is a strong indicator of sickness in dogs.
• Urination Issues. Excessive urination and dark or bloody urine could signal illnesses such as liver disease, UTIs, or kidney disease. 
• Thirst Level. Dogs that drink too much or too little water may have kidney problems or a fever.
• Weight Fluctuations. Weight gain or weight loss with no known cause may indicate an underlying health issue.

Mobility Issues

Dogs with joint issues, hip dysplasia, arthritis, fractured bone, infections, or other ailments may have trouble walking, rising, and jumping. If your dog is not taking stairs or jumping onto the bed or couch, as usual, this could be a sign that they are experiencing joint pain or have an existing injury. Dogs that show reluctance or stiffness when getting up may be exhibiting early signs of osteoarthritis. Lower activity levels and disinterest in play might also signal mobility issues.

Changes in Appearance of Gums

Dog's gums are pink and moist. Pale gums can indicate anemia or shock. Shock is a serious condition caused by trauma, blood loss, heatstroke, burns, infections, allergic reactions, poisoning, and other acute conditions. When dogs are in shock, their organs don't get enough blood or oxygen which can lead to permanent organ damage or even death. Other gum changes to watch out for include:

• Bright Red Gums. Inflamed gums are bright red in appearance and may indicate gingivitis.
• Blue Gums. Low oxygen levels can cause your dog's gums to have a blue tinge.
• Yellow Gums. Jaundice and certain bacterial infections have been known to cause yellow gums.
• Gum Texture. While gums naturally change texture as your dog ages, sudden texture changes could be a warning sign of developing health issues.
• Bleeding Gums. It is common for a dog's gums to bleed when chewing on something, however, if gum bleeding becomes chronic, there may be an underlying health issue.

Fever

Normal body temperature for dogs ranges from 101-102.5 degrees. Elevated temperature in dogs is related to a variety of conditions from bacterial, viral, and fungal infections to infected wounds, immune disorders, or even cancer. When taking your dog's temperature, lubricate the thermometer with something like petroleum gel or baby oil beforehand. Then, carefully place the thermometer about an inch inside your dog's anus and watch for the readings. Typically, the thermometers used for this purpose register within 60 seconds.

Itching and Gnawing

Itching, gnawing, and biting parts of their body are also signs that sick dogs may exhibit. These behaviors are associated with flea infestations, canine allergies, and certain infections, and are often accompanied by redness, hair loss, swelling, abnormal odor, and discharge. 

Behavioral Changes

Sudden behavioral changes in dogs, such as aggression, biting, or over-protectiveness of certain body parts, might also raise red flags. Aggression and biting, for instance, might be signs of canine rabies. Dogs may avoid contact or snap at you if they are in pain. If your dog starts acting, they may be sick or injured.

What to Do If Your Dog Is Sick

The best course of action for addressing canine illness or injury is dependent on the type and severity of the issue. 

• Energy Level and Sleep Problems. Changes in energy levels and sleep disfunction may be caused by serious underlying conditions that can only be identified with diagnostic tests and exams. Schedule a veterinary visit for your pet.
• Gastrointestinal Issues. Most gastrointestinal issues that are not severe clear up within two days. If symptoms persist beyond that, it's time to call your vet. 
• Mobility Problems. Lameness and stiffness from mundane causes usually resolves within a day or two, beyond that, your pet may need a veterinary examination.
• Gum Changes. Sudden gum changes, most notably pale gums, can indicate urgent conditions that put your pet's life at risk. Seek immediate veterinary assistance.
• Fever. At 103 degrees, your dog's temperature is considered elevated. Place a fan in front of your pet and cool towels around their ears and paws, then continue to monitor their temperature.
• Itching and Gnawing. Itching and gnawing are caused by conditions that can be treated and prevented with prescription and, sometimes, over-the-counter pet medications. Check with your vet to find the best treatment for your dog's itch issues. 
• Behavioral Changes. All conditions associated with behavior changes in your dog, especially aggression, are serious and require immediate vet care.

How to Help Your Dog Recover

Many pet owners experience feelings of helplessness and anxiety when their four-legged family member becomes sick, but the truth is that no one is more capable of helping your dog feel better than you. To that end, you should always administer medication at the proper times and treat wounds and dressings by your vet's instructions to speed up your dog's recovery from illness or injury. Most importantly, show your dog a lot of affection, reassure them that you love them, and encourage them to eat vet-recommended food. Also, make sure your dog has a cozy place to rest and recover in peace. As your dog starts to get better, you can re-introduce them to their normal routines and activities with permission from your vet.