Canine angiostrongylosis
The Canine Angiostrongylose is a parasitic disease in dogs caused by the French heartworm ( Angiostrongylus vasorum is triggered). The parasite attacks the pulmonary arteries and the right ventricle of the heart in dogs and primarily causes breathing difficulties and clotting disorders . The diagnosis is made based on the detection of larvae in the feces. Moxidectin and milbemycin oxime are used for treatment .
Pathogen
Adult worms are very thin (170–360 µm), 1.4 to 2 cm long, and pink. The females lay undifferentiated eggs, which enter their pulmonary capillaries via the bloodstream. The first larvae that hatch here migrate into the lower airways, are coughed up, swallowed and excreted with the feces. The elimination period ( patent ) is up to five years. Various species of snail serve as an obligatory intermediate host . In these the larvae develop into infectious larvae 3. Occasionally, frogs and rodents also serve as foraging hosts. If the dog eats an intermediate or paratenic host , the larvae L3 penetrate the intestinal wall and develop further in the lymph nodes of the abdominal cavity. They then reach the right ventricle and pulmonary arteries via the portal vein , liver and posterior vena cava , where they molt into adult worms. Since infectious larvae can also actively leave the snails, infection is probably also possible through ingestion of grass and dew. The prepatency varies between 35 and 100 days.
Originally, the parasite was mainly found in France , Denmark and the United Kingdom . The frequency of infestations has increased significantly worldwide for several years, so there are also endemic herds in the United States, South America, Australia and in the Asian part of Russia. The most recent figures in Germany show an infection rate of 7.4% in animals with a lung disease or 0.5% of the total dog population.
Pathogenesis and clinical picture
The larvae reach the pulmonary arteries ten days after peroral infection and cause focal interstitial pneumonia in the lungs . As soon as eggs and larvae appear in the pulmonary capillaries, granulomatous tissue reactions and scarring also occur. As the larvae migrate into the airways, bleeding also occurs into the lung tissue. A blood clotting in the blood vessels , an immune-mediated loss of platelets and a decrease in coagulation factors V , VII and von Willebrand with blood coagulation disorders are also typical. In the infected blood vessels, the adult worms also cause inflammatory - thrombotic changes. Depending on the severity of the infestation, right heart failure and cor pulmonale can also occur.
Occasionally the worms and larvae migrate to other parts of the body ( larva migrans , "wandering larvae"). In adult worms, migrations into the eyes , the left ventricle and the femoral arteries have been described ; in larvae in the brain , spinal cord , eyes, kidneys , liver , skeletal muscles , intestines , stomach , pancreas , spleen , adrenal glands and thyroid gland .
About 7% of the infected dogs do not show any clinical symptoms. The most common symptoms are cough, which occurs in two-thirds, as well as shortness of breath and fatigue. Some animals only show blood clotting disorders with bleeding in the skin and mucous membranes, with nosebleeds and with bruises . Also, lack of appetite , weight loss, vomiting and diarrhea may occur. When the larvae migrate into the nervous system, central nervous system failures can occur.
diagnosis
The clinical picture is not very specific. A chest x-ray can provide additional clues to detect changes in the lungs. The diagnosis is made by detecting larvae L1 in the faeces using the larval emigration method , whereby a 3-day collective sample increases the informative value. The larvae measure 310-399 µm × 14-16 µm and have a characteristic curve at the tip of the tail. The detection of larvae in a lung lavage sample is also possible.
The time-consuming larval migration process can be replaced by serological (sandwich ELISA , specificity 98.8%) or by PCR detection of angiostrongyle antigens . A rapid test ( IDEXX Angio Detect ) is available for serological detection .
treatment
In Germany, three drugs are approved for the treatment of angiostrongylosis. On the one hand, a combination preparation with the active ingredient moxidectin ( Advovate ), which is used twice, preferably monthly in endemic areas. The other two drugs contain milbemycin oxime as a pharmacologically active substance , which, when used monthly, reduces the infestation with larvae and adults.
literature
- Dieter Barutzki et al .: Angiostrongylus vasorum in dogs: current data on the spread in Germany and new findings on prophylaxis and therapy. In: Parasiten Spezial 1/2010, pp. 9-14.
- GA Conboy (2000): Canine Angiostrongylosis (French Heartworm) (PDF; 36 kB). International Veterinary Information Service
Individual evidence
- ↑ a b c Dieter Barutzki et al .: Angiostrongylus vasorum in dogs: Current data on the prevalence in Germany and new findings on prophylaxis and therapy . In: Parasiten Spezial 1/2010, pp. 9-14.
- ↑ a b c Dieter Barutzki: Nematode infections of the respiratory tract in dogs in Germany. In: Tierärztliche Praxis Kleintiere 41 (2013), pp. 326–336.
- ↑ J. Koch, JL Willesen: Canine pulmonary angiostrongylosis: an update. In: Veterinary Journal. Volume 179, number 3, March 2009, pp. 348-359, doi : 10.1016 / j.tvjl.2007.11.014 , PMID 18180185 (review).