Dog Diseases – Canine Heartworm Disease
Canine Heartworm Disease is a kind of filariasis caused by the canine heartworm parasitic on the right ventricle and pulmonary artery (rarely in the thoracic cavity and bronchus) causing circulatory disturbance, dyspnea and anemia. In addition to infecting dogs, cats and other wild carnivores can also be infected.
Pathogen and life history
Canine heartworm (also known as heartworm canine) is yellow-white in the shape of a slender fan. The males are 120-160 mm long, and the tails are spirally curled; the females are 250-300 mm long. Viviparous larvae are called microfilaria parasites in the blood, with a body length of 307 to 322 microns and no sheath.
Canine heartworms need canine fleas, Anopheles or Culex mosquitoes as intermediate hosts to complete their life history. The female parasitic in the right ventricle produces freely movable microfilaria, which enters the blood. When fleas and mosquitoes suck blood, they suck microfilaria into the human body and develop into infectious larvae, which enter the beaks of fleas and mosquitoes. When the ant sucks blood, the larva escapes from the beak and penetrates into the skin of the final host. It circulates to the heart and large blood vessels through subcutaneous lymph or blood.
(1) The earliest clinical symptom is chronic cough, but there is no other symptoms of upper respiratory tract infection, which is aggravated during exercise, or the sick dog is prone to fatigue during exercise. As the disease progresses, the sick dog develops heart palpitations, weak pulses and intermittents, and heart murmurs. The liver area is painful on palpation and the liver is enlarged. Water in the chest and abdomen, edema all over the body. Difficulty breathing. In cases of long-term infection, cor pulmonale is very obvious. In the final stage, he died due to general weakness or collapse during exercise. Sick dogs are often accompanied by nodular skin diseases, characterized by itching and multiple focal nodules that tend to rupture. Skin nodules are inflammation of the pyogenic granuloma in the center of the blood vessel, and microfilariae are common in the blood vessels around the pyogenic granuloma. X-ray photography showed that the right ventricle was dilated, and the aorta and pulmonary artery were dilated.
(2) Laboratory microscopy can make a preliminary diagnosis based on medical history investigation and clinical symptom observation. The final diagnosis should be made at night by collecting peripheral blood for microscopy to find microfilaria.
① Use thioarsamide sodium to drive away adult insects, at a dose of 2.2 mg/kg body weight, intravenously, twice a day for two consecutive days. During intravenous injection, it should be injected slowly, and the liquid should not leak out of the blood vessel, so as not to cause inflammation and necrosis of the tissue. Or use dichlorophenarsine hydrochloride at a dose of 2.5 mg/kg body weight, intravenously, once every 4 to 5 days. The drug has better deworming effect strong and low toxicity.
② Use levamisole to drive microfilaria at a dosage of 10 mg/kg body weight, orally, for 15 days. After the sixth day of treatment, check the blood. When no microfilaria is detected in the blood. Stop treatment. Or use ivermectin ( trade name vomec), the dosage is 0.05 ~ 0.1 mg/kg body weight, 1 subcutaneous injection. Or use fenthion, subcutaneously inject 0.2 ml of 7% solution per kilogram of body weight, if necessary, repeat 1 to 2 times every 2 weeks . Symptomatic treatment should also be carried out according to the condition.
(2) Preventing and eliminating intermediate hosts Preventing and eliminating fleas and mosquitoes is an important measure to prevent this disease. Medications can also be used for prevention: The oral dose of ethamazine (Hai Qunsheng) is 6.6 mg/kg body weight, and the Medication should be used continuously during the season of mosquitoes and flies. Dogs positive for microfilaria. It is strictly forbidden to use ethamazine to avoid allergic reactions and cause death. It is necessary to use medicine to kill adult worms and microfilaria before starting to use ethamazine for prevention.