Signs, Treatment And Diagnosis Of Dirofilariasis In Dogs

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Signs, Treatment And Diagnosis Of Dirofilariasis In Dogs
Signs, Treatment And Diagnosis Of Dirofilariasis In Dogs

Video: Signs, Treatment And Diagnosis Of Dirofilariasis In Dogs

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The roundworm dirofilaria immitis causes a cardiac form of dirofilariasis, also parasitizes in the pulmonary artery, settles in the right parts of the organ, and is a danger to the life of the pet. Subcutaneous dirofilariasis develops in dogs when infected with dirofilaria repens. The microfilariae of the worm penetrate the tissue, move under the epidermis, leaving behind abscesses.


  1. Mode of infection, flow forms
  2. Signs of infection
  3. Dirofilariasis cycle in dogs
  4. Laboratory diagnostics
  5. Analyzes
  6. Instrumental research method
  7. Dirofilariasis treatment regimen
  8. Treatment of cardiac and pulmonary forms
  9. Prevention of embolism
  10. Treatment of the skin form
  11. Prevention of dirofilariasis

Mode of infection, flow forms

Instead of eggs, female filamentous nematodes, reaching a length of up to 30 cm, immediately give birth to larvae. Microfilariae infect arthropod insects, where within 2 weeks they grow up, feeding on blood, become stronger, and then attack the body of a dog or cat. When a mosquito bites, microfilariae penetrate the animal's skin.

After the new owner enters the bloodstream, the nematode larvae turn into an adult after six months, or even later, live from 2 to 7 years, and when bitten again fall into the mosquito.

Parasites in a dog
Parasites in a dog

Dirofilariasis is usually found not in puppies, but in dogs over 12 months old. With a latex course, the symptoms of pathology in the animal are not observed, and microfilariae are detected by chance when examining blood. In a chronic disease, only a few signs appear, the number of which increases over time, a cough appears, the animal quickly gets tired, and loses its appetite.

The acute course of helminthiasis is dangerous due to the occurrence of pneumonia, pulmonary edema. The severe stage of dirofilariasis is fraught with the death of the animal due to the incapacitation of various body systems.

Signs of infection

The cutaneous form of the disease makes itself felt when the dog has a high intensity of invasion. In areas affected by worms:

  • wool falls out;
  • pustules are formed;
  • abscesses turn into ulcers;
  • discharge from the eyes appears.

Parasites moving under the skin cause itching, and the dog itches constantly, which increases irritation on the head, paws, back. Sometimes in animals between the phalanges of the fingers, tumors about 2 cm in size appear on the mammary gland.

Dirofilariasis of the heart in dogs
Dirofilariasis of the heart in dogs

The heartworm slowly infects the dog's organs. At first, the animal weakens, refuses to play, suffers from coughing, which over time does not stop even in the lying position. Nematodes that have penetrated into the blood vessels provoke tissue proliferation, attack the brain, enter the ventricle, and cause arrhythmias. The heart increases in size and puts pressure on the bronchi, which leads to shortness of breath in the animal. With the development of the disease in the dog:

  • vomiting with bile begins;
  • the neck is bent;
  • epileptic seizures occur;
  • the lungs are swollen.

The remains of filaria decompose, poisonous decay products cause intoxication of the body. Dead worms close the lumen in the vessels, impede blood circulation. The animal does not eat anything, loses weight, often faints. If respiratory failure occurs, the pet cannot be saved.

Dirofilariasis cycle in dogs

When a mosquito, which plays the role of an intermediate host, bites an animal infected with helminths, it swallows microfilariae with blood. Inside the insect, the parasites feed and grow, moving on to the next stage. If the mosquito attacks the dog again, mature larvae enter the animal's body along with the bite and cause dirofilariasis.

Infection of dogs with dirofilaria
Infection of dogs with dirofilaria

When the worms grow up to 3-11 cm, which usually takes 3-4 months, they begin to move to the heart, damaging blood vessels along the way. Sex-age helminths multiply and give birth to new microfilariae. The larva of the worm can reach the right ventricle, moving through the blood, in a few days, but usually this happens in 7–9 months, and only then does the animal show signs of the disease.

Seeing how a pet is suffering, the owner worries that dirofilariasis of dogs is dangerous to humans.

Laboratory diagnostics

To cure a pet of dirofilariasis, you need to determine the type of pathogen, the severity and form of the course.


If there is a suspicion of infestation with roundworms and the presence of dirofilariasis, several laboratory methods are used:

  1. Knott's method: Two milliliters of blood taken from a dog's vein is mixed with 10 ml of liquid 2% formalin and sent to a centrifuge for 5 minutes. A drop of sediment is placed on glass, and dead microfilariae can be detected under a microscope.
  2. In native serum. A couple of millimeters of blood from a vein is poured into a test tube, where a clotting accelerator is added, sent to a centrifuge for 10 minutes, after which drops of serum are removed next to the formed clot, transferred to a glass, covered and the moving microfilariae are examined under a microscope.
  3. Staining method. 10 ml of distilled water is poured into a test tube, mixed with serum, scrolled in a centrifuge, then the liquid is decanted, the precipitate is spread on glass, and a special set of preparations for staining is added. The microfilariae body becomes yellow or pink,
Microfilariae under a microscope
Microfilariae under a microscope

In addition to laboratory research, the dog is tested for antibodies, the antigen is detected using immunochromatographic analysis, and a chest x-ray is taken. In the cutaneous form of the disease, worms are sometimes detected when they crawl out of the pustule.

Instrumental research method

Diagnostics by ultrasound helps to identify abnormalities in the kidneys, liver of the animal, to assess the condition of the abdominal cavity. An electrocardiogram and ECHO-KG are prescribed to determine the heart rate, changes in the work of the organ. The x-ray shows damage to the pulmonary artery, ventricular hypertrophy.

Dirofilariasis treatment regimen

The severity of the disease is influenced by the number of parasites, the duration of the pathology, the conditions of the animal, the presence of resistance to dirofilariasis in the dog.

Treatment of cardiac and pulmonary forms

It is not always possible to save a pet if it is struck by a heartworm. Although the symptoms of both forms of the disease are different, and in both cases, special drugs for diphilariasis in dogs will be required, treatment begins with the destruction of adult helminths, as well as:

  • get rid of microfilariae;
  • toxins are removed from the dog's body;
  • start therapy aimed at eliminating symptoms.

In order for the sick animal to move less, retain the strength to fight helminthiasis, it is placed in a cage or aviary. Pulmonary dirofilariae in dogs are dangerous by blockage of blood vessels. If testing has shown that the likelihood of blood clots is low, the pet is injected with the first injection of the anthelmintic agent Immiticide, the second injection is given no earlier than a month later, the third - a day after the second. The drug destroys adult worms, but is not suitable for combating dirofilariasis in dogs suffering from kidney and lung pathologies.


It is recommended to treat dirofilaria immitis in weakened animals with Ivermectin. The agent acts on the neurons of the parasites, and the worms die as a result of paralysis. The drug is administered intramuscularly to dogs, except for collies, bobtails and animals of some other breeds, once a week, repeat up to 5 procedures.

Levamisole copes with both types of dirofilariae, it is taken for a longer period than other anthelmintic drugs.

Immiticide (Melarsomin) is injected into the muscle 2 times every other day. The drug kills adult worms, but does not affect microfilariae and larvae.

Dironet affects the larval stage of development of dirofilaria.

Advocate drops, which contain 2 active ingredients - moxidectin and imidacloprid, are applied to the animal's fur. The composition stimulates the release of gamma-aminobutyric acid, paralyzes helminths.

Prevention of embolism

To prevent the development of pulmonary embolism:

  • Alteplase is injected into a dog's vein;
  • for the prevention of clots, Heparin is prescribed;
  • to improve cerebral circulation, Curantil is prescribed.

Acetylsalicylic acid, recommended by a veterinarian for cardiac dirofilariasis, reduces platelet clumping, inhibits the formation of prostagladins.

When the lungs are affected by pneumonia, Cefotaxime is included in the treatment regimen, which gives a bactericidal effect, glucocortistoroid Prednisolone, Sodium Thiosulfate, which neutralizes toxic substances. A month after the completion of drug therapy, the dog's blood is examined for the presence of microfilariae. Repeated tests are done six months later, and if the worms are not found, the danger to the pet's life has passed.

When the worms are found in the area of ​​the heart, the veterinarian removes them with special forceps, monitoring the process using echocardiography. After the operation, the dog is injected with Immiticide, the drug is replaced with Doxycycline, if arsenic compounds are contraindicated for the animal.


Treatment of the skin form

The areas of the dog's body affected by worms are treated with erythromycin or tetracycline ointment, and warming compresses are applied. With dirofilariasis of the skin type to a pet:

  1. Injections of Ivermectin are given.
  2. Milbemax is given inside.
  3. A solution of the anthelmintic drug Advocate is dripping onto the withers.

When localizing nematodes in the conjunctiva of the eye, under the eyelid in a veterinary clinic, parasites are removed with tweezers. Doxycycline is used after the intervention to prevent inflammation.

Prevention of dirofilariasis

In order to prevent infection of the dog with dirofilaria, you need to protect the pet from insect bites, for which deterrent agents are used. If the animal is kept in a house or apartment, fumigators are purchased.

During a warm period, you cannot take your pet outside without treating it with a mosquito spray. Preparations for fleas and ticks do not cope with dirofilariae, you need to buy special means. Anthelmintic tablets should be given to dogs at the beginning of spring and should be repeated no later than 3 months later.

Dironet for dogs
Dironet for dogs

They prevent infection with nematodes, Nexgard and Milbemax preparations are used to prevent dirofilariasis, Advocate's solution is dripped onto the splitter.

It will take a lot of time and money to treat dirofilariasis in dogs to cure an animal of helminthiasis caused by the nematode dirofilaria. If the disease is neglected, the chances of saving the pet are reduced to zero, since the parasites infect the heart, destroy the lungs, and the animal dies.

Some owners are worried that they may contract dirofilariasis from the dog, but the pet does not tolerate pathogens of the pathology. A person, like other animals, can catch a disease when bitten by a mosquito. A seal appears on the skin, in which microfilaria grows and turns into a larva, helminthiasis manifests itself in the cutaneous form.

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