Heartworm is one of the most serious ailments common in domestic dogs. Although most dogs are routinely vaccinated for heartworm as puppies and then periodically throughout their lives, many animals fall through the cracks because they are strays or have had irresponsible owners. Dogs with untreated heartworm are subject to severe health issues, including liver failure, and may eventually die if the condition is not discovered and treated. It is important to know the signs of heartworm in dogs, especially when working with dogs of unknown medical history, such as those in animal shelters or purchased from pet stores.
Signs of Heartworm
Symptoms vary in severity, duration, and the stage of infection at which they appear. The most common signs of heartworm in dogs include a cough, lethargy, and a dull coat. As the heartworm progresses, the dog may experience fainting spells and show a severe drop in weight -- which may result from a loss of appetite or may be otherwise unexplained -- as well as have increased difficulty breathing. Additional symptoms may include hair loss, vomiting, a rapid pulse, jaundice, and sometimes convulsions or even blindness.
Though the primary area of infection is the heart, the lungs are heavily affected and most other systems may have some kind of damage as a result. Sometimes the worms will infect the liver and kidneys as well, which may or may not produce additional symptoms. Because so many different systems are affected, the signs of heartworm in dogs are often mistaken for other conditions, most of them far less serious than heartworm. Many owners mistake the more common symptoms for kennel cough, pneumonia, or asthma.
Problems with Symptomatic Diagnosis
The signs of heartworm in dogs are varied, and many of the symptoms are related to other conditions as well, so a definite diagnosis is impossible without a blood test from the veterinarian. However, it is also important to note that if the dog has an unknown medical history -- especially in places where exposure to mosquitoes is likely -- a blood test should always be done whether or not the dog appears sick. The infection rate for dogs where no preventive measures have been taken is extremely high in higher-risk areas, namely throughout North America and South America.
The signs of heartworm in dogs appear only when the condition is already far advanced; it may no longer be possible to successfully treat the dog by that point. Dogs that are successfully treated after showing severe signs may suffer from permanent internal damage as a result. The specific symptoms, if any, that show up depend largely on the individual animal and the extent of the heartworm infection.
