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Common Dog Disease

Common Dog Disease

Posted by ASPCA on Nov 24th 2022

As a dog parent, it is important to recognize the signs and symptoms of common illnesses so you can seek veterinary help for your canine friend as soon as possible. Read on for information about diseases and other medical inflictions that frequently impact dogs.


Cancer is a class of diseases in which cells grow uncontrollably, invade surrounding tissue and may spread to other areas of the body. As with people, dogs can get various kinds of cancer. The disease can be localized (confined to one area, like a tumor) or generalized (spread throughout the body).

Causes of Cancer

Cancer is a “multifactorial” disease, which means it has no known single cause. However, we do know that both hereditary and environmental factors can contribute to the development of cancer in dogs.

Cancer Symptoms

Symptoms of cancer in dogs may include:

  • Lumps (which are not always malignant, but should always be examined by a vet)
  • Swelling
  • Persistent sores
  • Abnormal discharge from any part of the body
  • Bad breath
  • Listlessness/lethargy
  • Rapid, often unexplained weight loss
  • Sudden lameness
  • Black, tarry stools (a symptom of ulcers, which can be caused by mast cell tumors)
  • Decreased or loss of appetite
  • Difficulty breathing, urinating or defecating


It is important to understand that diabetes is considered a manageable disorder—and many diabetic dogs can lead happy, healthy lives.

Diabetes can be classified as:

  • Type I (lack of insulin production)
  • Type II (impaired insulin production along with an inadequate response to the hormone).

The most common form of the disease in dogs is Type I, insulin-dependent diabetes, which occurs when the pancreas is incapable of producing or secreting adequate levels of insulin. Dogs who have Type I diabetes require insulin therapy to survive.

Diabetes Symptoms in Dogs

The following are signs that your dog may be diabetic:

  • Change in appetite
  • Excessive thirst/increase in water consumption
  • Weight loss
  • Increased urination
  • Unusually sweet-smelling or fruity breath
  • Lethargy
  • Dehydration
  • Urinary tract infections
  • Vomiting
  • Cataract formation, blindness
  • Chronic skin infections


Heartworm disease is serious and can be fatal.

Heartworm Symptoms

Symptoms of heartworm can include:

  • Labored breathing
  • Coughing
  • Vomiting
  • Weight loss, listlessness and fatigue after only moderate exercise
  • Some dogs exhibit no symptoms at all until late stages of infection

Kennel Cough

Though it usually clears up on its own, kennel cough is highly contagious to other dogs.

Symptoms of Kennel Cough

  • A persistent dry cough with a “honking” sound.

In most cases, she’ll appear healthy except for the cough.

  • Gagging
  • Coughing up white foamy phlegm
  • Fever
  • Nasal discharge


The virus attacks rapidly-dividing cells in a dog’s body, most severely affecting the intestinal tract. Parvovirus also attacks the white blood cells, and when young animals are infected, the virus can damage the heart muscle and cause lifelong cardiac problems.

Parvovirus Symptoms

The general symptoms of parvovirus are:

  • Lethargy
  • Severe vomiting
  • Loss of appetite
  • Bloody, foul-smelling diarrhea, which can lead to dehydration


Symptoms of Rabies

Animals will not show signs immediately following exposure to a rabid animal. Symptoms can be varied and can take between two and eight weeks to incubate. Classic signs of rabies in dogs include:

  • Changes in behavior (including restlessness, apprehension, aggression or irritability)
  • Biting or snapping at any form of stimulus
  • Attacking other animals, humans and even inanimate objects
  • Licking, biting and chewing at the bite site
  • Fever
  • Hypersensitivity
  • Hiding in dark places
  • Eating unusual objects
  • Paralysis of the throat and jaw muscles
  • Foaming at the mouth
  • Disorientation, incoordination and staggering
  • Paralysis of the hind legs
  • Loss of appetite
  • Weakness
  • Seizures
  • Sudden death


Ringworm Symptoms

Classic symptoms of ringworm in dogs include:

  • Skin lesions that typically appear on the head, ears, paws and forelimbs.
  • Ringworm can patchy, crusted, circular bald spots that sometimes look red in the center
  • In mild cases, there may be just a few broken hairs, while bad cases can spread over most of a dog’s body.
  • It’s also possible for a pet to carry the fungus and not show any symptoms whatsoever.

Dogs More Prone to Ringworm.

  • Puppies less than a year old are most prone to infection
  • Malnourished, immunocompromised and stressed dogs are also at a greater risk.
  • Ringworm can quickly spread in kennels, shelters and other places where there are many dogs in a close environment.

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