Heart worms in dogs caused by Dirofilaria immitis, these worms is a type of nematode worm Filaria. Dirofilaria immitis is also known as Filaria sanguinis or Dirofilaria lousianensis, is a worm of the genus Dirofilaria causes of Canine heartworm disease (CHD) in dogs. Adult worms are commonly found in dogs almost all over the world, particularly in tropical and subtropical regions, including in Indonesia. Natural infection in healthy dogs preceded by Anopheles and Culex mosquitoes carrying infective larvae microfilaria stage 3 (L3). The larvae then develop in the subcutaneous tissue and fascia of the patient intramuscularly for about 2 months later into the form of "immature" and began migrating to the right ventricle of the heart and pulmonary arteries. Ripening or maturity of worms occurred after 6-8 months pascainfeksi. Female worms become adult worms and produce microfilaria that can be found in the blood. Perfection of the life cycle of D. immitis occurred when another mosquito sucking new microfilaria along with taking or sucking blood from people with dogs.
Pathogenesis of Heart worms
In the case of Canine heartworm disease is found ample pathological changes, especially in the lungs and pulmonary arteries. These changes are caused by the host's reaction to the antigen D. immitis and of secondary events such as thrombosis. Imflamasi signs describing the overall host response to lesions. The main symptoms of increased blood flow to the site of infection.
Swelling and pain as a result of the biological activity of various system imflamasi the complement cascade system, Hageman factor dependent coagulation pathway, kinin activity, chemical mediators from mast cells and basophils, arachidonic acid metabolism products as well as excess fat. Activity and secretion of these mediators cause changes in vascular permeability and recruits sekreton cells derived from local and circulation to participate in the process imflamasi.
Clinical symptoms of Heart worms
Many of the infected dog and carnivore D. immitis often do not show clinical symptoms (subclinical), but found the microfilaria in the blood. In the early stages (mild infection) respiratory symptoms develop slowly and lethargy.
In severe cases there are signs of mechanical disruption caused by circulatory disturbances and progressive endarteritis. Ednokarditis, thromboemboli, and fever were reported in severe cases. In cases where there are adult worms in considerable numbers, patients will show impaired function of heart valves, especially if the worms are in the right atrium, right ventricle and the pulmonary artery the upper third. Had right heart dilatation and hypertrophy. This situation led to the damming of the vein with liver cirrhosis and ascites.
Death often occurs due to the occurrence of emboli and thromboembolism because terdamparnya D. immitis adults who die in the pulmonary artery branches. Dead adult worms induces changes in the pulmonary artery within 3-6 weeks. Thrombi, and extensive proliferation of villi due inflamsi granulomatous response will inhibit blood flow to the lobe of the lung kaudalis. This syndrome is characterized by the onset of fever, dispnoea, tachycardia, hypotension, weakness, cough or hemoptysis.
The rate of anemia in dogs infected with the higher (37%) than non-infected dogs (14%) and more in animals with vena cava syndrome (91%) compared to animals "occult dirofilariasis" (62.5%) while the onset of hemolytic anemia and hemoglobinuria is a hallmark of the vena cava syndrome.
Diagnosis of Heart worms
Clinically, the picture of infection D. immitis vary widely depending on the number of circulating microfilaria and the adult worms that washed up on the organ. Based on the anamnesis found weight loss, physical weakness, spontaneous cough, subcutaneous fluid accumulation, high body temperature with a mucous membrane cyanosis. X-ray image appears on the right heart hypertrophy and dilatation, spontaneous cough, increased vascularization of the thoracic region, the damming of the vein with ascites. Microfilaria only be found if the examination of fresh blood preparations or to review the specific acid phosphatase staining taken at night.
For identification of microfilaria D. immitis by using the Modified Knott's Test (MKT). for serodiagnosa, an immunoassay technique to infection D. immitis is DIRO-Chech ® and ELISA-Ag-Test that has been produced commercially. This kit is to detect the presence or absence of a mild infection or infection "occult".
D. immitis worms have to be distinguished from the subcutaneous Dipetaloma reconditum 260-280 microns in length and 6-7 microns wide, tip shape, blunt head and tail to tail "botton hooked", moving forward. In addition itun also reported a diagnosis of appeal is D. repens and D. dracunculoides.
Prevention and treatment
In general, high and low success rate of therapy in the case of D. immitis in dogs depends on the severity. Tissue damage in which D. immitis adults, living or dead. For the treatment Thiacertasamida (Arsena preparations) at a dose of 0.2 ml / kg or 2 mg / kg divided into 2 doses given intravenously for 2-3 days. Six weeks after therapy with preparations Arsena followed by elimination of microfilaria using Levamizol HCl 10 mg / kg bw / day for 15 days is given orally. Ivermectin can also use the maximum dose of 6 mg / kg bw with a repetition interval of 30 days (ivermectine usage is not allowed to dog coli). Can also use anthelmintika type diethylcarbamazine citrate at a dose of 3-5 mg / kg bw per oral.
Preventive measures to control the vector mosquito Anopheles and Culex. In countries Diethylcarbamacin 4 seasons (DEC) at a dose of 5 mg / kg bw / day administered to dogs puppies into the summer, when mosquito exposure is high and treatment was stopped entering the winter.
For the conditions in Indonesia, the precautions recommended to be done throughout the year, but is rarely performed because of clinical case reports are extremely rare.