The earliest signs that your dog is sick are often changes in appetite or behavior. Your dog may stop eating or become less playful and energetic than usual. Depending on their age and the disease, your dog may have difficulty moving due to arthritis or other diseases that affect the bones and sick. Increased aggression or clingy behavior are also signs that your dog may be sick.No one knows your dog (or loves them) like you do, so you may be their first line of defense in detecting a chronic illness. Familiarize yourself with the following signs and the diseases they may indicate:

8 Signs Your Dog May Be Sick

Excessive drinking

Excess water intake is often a sign that your dog is sick and losing water at an unhealthy rate. Extreme thirst, or polydipsia, can be an early indicator of several serious illnesses. In addition to excess thirst, your dog may also experience an increased appetite, hair loss along the back, and increased panting. Contact your vet for a diagnosis if you notice any combination of these symptoms.

Cloudy eyes or discoloration

Red eyes in dogs often indicate a negative reaction to an environmental allergen. However, red may also be the result of a tear or injury to the eyelid or tissue. Dogs may have cloudy or bluish-gray eyes as a sign of cataracts or nuclear sclerosis, a normal change in aging eyes.


Most dogs don’t vocalize their pain until someone tries to touch them. If your friendly pup suddenly starts growling when people approach, he may be guarding a painful body part or injury. Seek veterinary care if you notice this sign that your dog is sick—he may have sustained an injury in a fight, fall, or accident.


Chronic coughing in dogs can be an early sign of lung disease, heartworms, or other heart diseases. A harsh, hacking cough is a common symptom of canine infectious tracheobronchitis, or kennel cough. As the name suggests, kennel cough is most often contracted from other dogs in crowded areas like dog parks, shows, and daycare facilities.For most dogs, symptoms of kennel cough typically go away within two weeks. Puppies with kennel cough, however, may be at risk of contracting pneumonia. Furthermore, kennel cough and other respiratory problems are often more severe for dog breeds with flat faces, such as boxers, bulldogs, and Boston terriers.

Dry, itchy skin

For young dogs, dry and itchy skin is often a sign of an adverse reaction to a food in their diet. Dry skin may also indicate a flea allergy or atopic dermatitis. Dermatitis can affect dogs of any age, and is often accompanied by recurrent ear infections.

Sores and skin ulcers

Skin ulcers and sores can be signs of food allergy or other nutritional disorders. Severe and widespread sores may be the result of a fungal or bacterial infection, autoimmune disorder, congenital disorders, and parasites. If the top layer of your dog’s skin has been compromised, it may result in skin lesions and ulcers that affect the deeper layers.

Hair loss

The most common causes of hair loss are ticks and fleas, but it may also be a sign that your dog has a more serious illness. Like dry skin, hair loss can indicate food allergies, and is often accompanied by redness and hot spots. Hair loss in dogs may also be a sign of hormonal imbalances such as thyroid disorders, pituitary dwarfism, and adrenal gland deficiency.


If your dog has difficulty in walking or rising, it may be an early sign of arthritis, disc disease, ruptured ligaments, or hip dysplasia, which causes the hip joint to develop abnormally. Hip dysplasia most often affects larger dogs, making it difficult to bear weight on the affected leg.Though arthritis and stiffness are often signs of aging, there are many veterinary tools and practices to improve your dog’s quality of life in their golden years. If you notice stiffness as a sign that your dog is sick, contact your vet to discuss options to preserve their mobility for as long as possible.