Heart worm Clinical Signs of Infection
Heartworms are a type of filarial worms that live in the lung arteries of dogs (primary host), cats, wolves, ferrets, coyotes and foxes. These parasitic round worms may interfere with proper pumping action of the heart and irritate the blood vessels in the surrounding areas of the heart and lungs. If left untreated, the condition may lead to death.
Young larvae may be detected in the dog’s blood around 6 to 7 months after the bite of a mosquito harboring the larvae. The female heartworms (ten to twelve inches) and the males (four to six inches) becomes fully matured a year after they have entered the dog’s blood and can live inside the system between five and seven years. Microfilaremia, the occurrence of heartworm larvae in the dog’s blood, is fairly common. There are times when the microlarvae do not circulate in the blood (occult infection) which may be caused by several factors such as an infection of heartworms with only one sex, the immune responses of the dog and the dog’s intake of preventive medications for heartworm. So what are the heart worm clinical signs of infection pet owners have to look out for in order to save their canine friends?
Dogs do not show heart worm clinical signs of infection during the pre-patent period which usually lasts for six months after the bite. There are rare occasions when the microlarvae become “lost” during their migration and end up in the eyes, artery of the leg or brain and manifest unusual heart worm clinical signs of infection such as blindness, lameness and seizure. But most of the time, no clinical signs are noticed until the parasitic roundworms mature. At times, the dogs do not manifest any symptoms even if the larvae have matured already. These dogs are usually are lightly infected and are fairly sedentary.
Therefore, the severity and onset of the heartworm clinical signs of infection is basically an indication of the number of adult heartworms at hand, the level of the dog’s activity and the age of the dog. Heart worms less than fifty in a 25-kilogram dog are concentrated at the caudal pulmonary arteries (lower lobes of the lungs). More than this would result to a positive infiltration of the worms at the heart’s right chambers. When this occurs, the most frequent pathological changes are the result of the inflammatory processes occurring at the arteries in the lung’s lower lobe due to the presence of the parasitic roundworms. Eventually, the heart has to work faster to compensate for the problem thereby overworking it. This would weaken the heart causing congestive heart failure and increased workload of the heart. There are times when a large number of heartworms will reside in the caudal vena cava located between the heart and liver. These worms need to be immediately removed surgically to prevent the occurrence of unexpected collapse and death in 2 to 3 days time. An overly active dog will develop a more severe heartworm clinical signs of infection even with a small number of roundworms present.
The disease may cause several other medical problems in a dog. Heartworm clinical signs of infection would include early signs such as cough (especially on exercise) and easily getting tired. More severe symptoms include severe weight loss, coughing of blood, fainting, congestive heart failure, vomiting, persistent pneumonia, hepatomegaly, ascites, syncope, abnormal heart sounds and abdominal distention. In more severe cases, death may be inevitable.
Early detection and prevention are the main things that you need to do to help protect your dog from experiencing these heartworm clinical signs of infection. Your vet would recommend monthly intake of preventive medications for this disease such as ivermectin, moxidectin, selamectin and milbemycin.