Canine filariosis


Injections and pills of an antiparasitic nature are the methods used to treat a dog suffering from filariosis

  • Publication date: August 9, 2013

The canine filariosis It is a disease caused by a parasite that can lead to serious consequences for the dog's health. This pathology is known as heart worm disease, because it is in this organ where the parasite that attacks the dog is housed. The following is explained. how filariosis is cured in dogs, the importance of early diagnosis and treatment of the disease and the incidence of filariosis in Spain.

Filariosis in dogs, a dangerous disease

A dog infected with filaria can infect other dogs and cats, but not people

A dog suffering from filariosis can die if he does not receive adequate treatment in time. That is why diagnosis is crucial for the life of the animal.

The process that follows this disease has its start at the moment when an infected mosquito of filaria bites a dog and, through its saliva, deposits the larvae of the parasite. It is then when the larvae develop under the dog's skin and travel through the veins to the heart, where they become adult worms that can reach up to 30 centimeters.

Canine filariosis is not transmitted to people. "The filaria worm is a specific parasite of canids, like dogs, which can also inhabit domestic cats," explains veterinarian Aitor Llamas.

How is filariosis cured in dogs?

The bite of the filaria mosquito can be prevented with antiparasitic and treated with injections

If canine filariosis is not very advanced, the disease has a cure with a specific treatment determined by the veterinarian. The method to treat this pathology consists of the application of two injections that cost around 100 euros each and they are very effective for their antiparasitic effect. In this way it is possible to eliminate the parasites that have reached the heart and become worms.

On the other hand, we must also eliminate the parasite larvae (the eggs of worms) from the dog's body. To achieve this, some are used deworming pills. This treatment implies side effects for the health of the dog, as there is a risk of thrombus formation, due to the creation of blood clots in the dog, due to the obstruction that the parasite causes in the vessels when it dies from the medication.

Therefore, veterinarian Leire Jiménez advises that before the treatment against filaria is started, "the dog should be administered for a few weeks. aspirin", which acts as a blood anticoagulant and helps prevent dangerous thrombi.

The repose It is essential during treatment. It is necessary to restrict the time of the walk, as well as any type of physical exercise, since it is key to prevent the massive detachment of dead worms by the injectable treatment and the appearance of blood clots.

In some cases where the state of the animal is more serious, the hospitalization to monitor its evolution and ensure maximum immobility.

Filariosis in dogs: the importance of early treatment

In cases where the dog is invaded by adult filarial parasites, a surgical intervention to extract them. Hence, in order to avoid passing through the operating room, the early diagnosis of filariosis is important. The sooner veterinary treatment is started, the more likely it is to prevent the invasion of parasites. And is that the risk to the animal increases considerably, if the diagnosis and treatment are late.

The cure of the dog with filariosis depends on the early diagnosis and treatment of the disease

The treatment of canine filariosis has three aspects. On the one hand, the usual symptoms It causes the disease, such as respiratory problems, cough, chronic tiredness or weight loss and tachycardia. On the other hand, the worm and larvae removal. Finally, a preventive action to avoid more bites from filaria infected mosquitoes that can contaminate the dog again (insect repellent products).

Typically, the treatment against canine filariosis lasts three weeks and the animal recovers, although it has to do controls to verify that the parasites have been eliminated.

Filariosis is an endemic disease in Spain. That is, it is located in certain areas that have specific climatic conditions that act as a breeding ground for the proliferation of parasite-transmitting mosquitoes in dogs. In the warmer, wetter areas and where rivers, lakes and stagnant water environments abound there are more mosquitoes transmitting the filaria.

A study by Fernando Simón Martín, from the University of Salamanca, on the incidence of filariosis in Spain, yielded the following data: the largest on the canine population occurs in the Canary Islands, and behind are Menorca, Huelva, Tarragona and Alicante.

What is canine filariosis and how is it spread?

It is the disease that gives name to the infection of the filarial parasite in dogs, it is also known as the worm disease in the heart. Its infection is given by the peck of a mosquito, which must have previously bitten a dog infected with this disease. When the mosquito bites a sick dog, it absorbs part of its blood to feed but also the larvae of this disease, so that when it bites another dog, it also infects the filaria lavas.

Filaría lavas circulate in the bloodstream of infected dogs, the ones that develop make it the heart of our dog, where they become adult worms that feed on the nutrients they absorb from our dog. Adult worms can measure several centimeters long, invading part of the lung and also damaging the liver.

What are the symptoms of filariosis in dogs?

Unfortunately when we can observe the symptoms in our dogs it will have been too long, so surely our dog will have a major infection of Filariosis. As we say, the symptoms appear late and can also be misinterpreted, so surely the infection of parasites is already widely spread in our dog.

The most common symptoms are:

  • Cough smooth and chronic
  • Breathing acceleration
  • Tiredness and general sadness
  • Sometimes lack of appetite
  • Attacks during exercise

How is filariosis spread?

This parasitic disease it is spread through the bite of a mosquito, which must have previously bitten a dog that already has filariosis. Once the larvae enter the animal's body they circulate through the bloodstream until they reach the heart, where they will develop while endangering the health of the dog, since they feed on the nutrients that the animal absorbs.

What is the treatment to cure Filariosis in a dog?

Depending on when we detect the disease in the dog, we can cure it with a treatment based on medicines or on the contrary we will have to intervene surgically, operate it. If our dog is only infected with larvae, it is very likely that through a treatment provided by our veterinarian, based on two injections and some pills, we can cure it.

If our dog is in an advanced state of infection, it is likely that it already has adult worms in its heart, so it would have to be operated to extract them. Once operated, a medical treatment should also be followed to eliminate the rest of the larvae.

Whether you only need a treatment or if you have to operate it, during the time you are given medication we must provide you with an almost absolute rest. While the larvae die from medicines, it is possible that our dog suffers some collapse in his bloodstream, so we should avoid any type of exercise until he is fully recovered.

How to prevent canine filariosis?

Preventing them is very simple, we simply have to take our dog to the veterinarian so that they are a simple blood test to tell us if our dog is healthy or infected. If it is healthy, we should simply give it one pill per month that acts as an antiparasitic. Thus preventing our dog from contracting the disease.

The mosquitoes that transmit this parasite normally live in humid areas with warm or temperate climates. Outskirts of rivers, swamps or lakes can be a source of infection.

How is this disease transmitted?

Its contagion is given by the bite of a mosquito of the Culex species. This mosquito bites a sick dog by absorbing part of its blood with larvae. By biting another dog, it infects 1 to 3 larvae for each bite. Filaria lavas circulate in the bloodstream of infected dogs maturing until they reach their heart, where they become adult worms. These worms can measure up to 30cm long inside the heart, invading part of the lung and also damaging the liver.

What symptoms does a sick dog have?

The symptoms we see in a sick dog are symptoms caused by the presence of adult worms.

The most common symptoms are very nonspecific: tiredness, chronic cough, lack of appetite, weight loss, agitated breathing or even attacks during exercise can be one of them.

How can I know if my dog ​​has Filariosis?

The most important thing in the case of Filariosis is to be able to make an early diagnosis before the animal develops symptoms, that is, before the worms are in the heart.

It is recommended to perform a blood test, once a year, because an animal that has been negative every year, if a year is positive, we know that it has contracted the disease that same year, so the probability of carrying out a Successful treatment is very high.

Is this disease treated?

Yes, there is treatment that involves eliminating adult worms and larvae with the least possible complications.
It is an expensive and complicated treatment because we must have the animal almost completely at rest while the worms die because of the medications, the animal's life being in danger.

How can I prevent filariosis?

Once we have performed the blood test to see that our dog is healthy, we have several options to prevent him from getting this disease:

1. Prevent the mosquito from biting our dog: we already have pipettes like Effitix ® on the market that repel 4 weeks of Filaria and Leishmania mosquitoes, fleas and ticks.

2. Kill the larvae in case the mosquito bites our dog. This can be achieved with a puncture antiparasitic once a year (Guardian ®) or a pill once a month (Milpro ®) at risk months.

Canine filariosis

As we said, it is important to know that the filaria is going to be installed in the heart of our dog and that, in addition, it is transmitted by mosquito bites. Filaria in dogs can occur around the world, although with different rates of infection, and dogs that live abroad are affected more.

The dog is infested when a mosquito bites it, carrying in its mouth larval infestants of filaria that are introduced into its body at that time. The larvae are able to dig into the skin and they undergo different modifications until they reach maturity. They can be tackled with several drugs, depending on the vital phase in which they are found.

Immature worms reach the bloodstream and travel until they end up in one of heart cavities, the right ventricle, and the pulmonary arteries, where they continue to mature. When the number of worms is very high, they can also be transferred to the right atrium and even to cava and hepatic veins. Through the pulmonary arteries they can affect your circulation, obstructing blood flow and forming clots, which can also happen after treatment.

This disorder is known as "pulmonary embolism"and can lead to heart failure. In addition, worms near the valves of the heart can interfere with its functioning, so it will appear that the dog suffers from a valvular disease. Worms in the cava or liver veins are responsible for the syndrome of vena cava, the cause of liver failure that can occur with jaundice, ascites or anemia.

Approximately six months after the entry of the filarias in the dog, they become adults, reaching a size of up to 30 centimeters. They can live several years. Females generate microfilariae that are also capable of survive for years in the circulatory system.

If a mosquito bites the dog again it can ingest the blood contaminated with them. In the mosquito they will undergo modifications for 10-15 days, depending on the weather, and they will move to their mouth organs to become infestive again, thus restarting the cycle as soon as the mosquito bites another animal. As we see, filariosis in dogs may have serious consequences, hence the importance of influencing its prevention.

Symptoms of canine filariosis

The clinical manifestations of filaria in dogs are going to depend on the number of worms that are producing the infestation, as well as the size of the dog. A minimum number of filarias is needed to make the symptoms visible. With few copies, the dog will remain without symptoms.

The symptoms of filaria in dogs are:

  • Fatigue
  • Lack of predisposition when doing physical activity
  • Slimming
  • Cough
  • Accelerated breathing
  • Fainting, especially before exercise
  • Dogs with liver or lung involvement can suffer collapse and death

Diagnosis of canine filariasis

If a dog has any of these symptoms and is in an area where filariasis is common, it must enter into the differential diagnosis. It is essential go to our veterinarian, who can detect the presence of filarias in the blood using several methods. Sometimes there are difficulties in confirming the diagnosis by the number of parasites, the life cycle phase in which they are, etc.

In addition, the bone scan, which will show the damage that the parasites have caused in the heart and lungs, which allows to know the severity of the state of the dog. The electrocardiogram It can also provide valuable information, as well as blood analytics, which detect anemia, as well as possible liver or kidney disorders.

Treatment of canine filariosis

The treatment of filaria in dogs will depend on the state of the animal and the degree of infestation, hence the importance of performing the necessary tests to have as much knowledge as possible of the clinical situation of the dog. Based on all this, a distinction is made between dogs for which high risk of thromboembolism is anticipated during treatment, as we have already mentioned, and others with low risk of this complication occurring. Each of these groups has the following characteristics:

  • Low risk: It would correspond to dogs with low parasitic load and no more injuries. It usually has no symptoms and they have no other diseases. The x-ray is normal and filariae are not seen on the exam. In addition, you can remain at rest during treatment, as this carries risks.
  • High risk: are dogs that have symptoms and alterations in their radiographic examination. Parasites are observed and there are concomitant diseases. You can not limit the activity of the dog during treatment.

In any case, the treatment should be administered under strict veterinary control and take into account the moment of the life cycle of the filaria, since we will find more or less adult individuals in the same dog. Adult filarias are usually eliminated in a staggered manner to try to avoid the risk of thromboembolism. For the same reason physical activity is restricted.

There is also the possibility of remove worms by surgery, in some cases. Months after the end of the treatment it is advisable to retest the dog to verify that the healing has been complete.

We have already seen that filaria in dogs causes important disorders that they can be deadly and, also, the complications involved in its treatment. For all these reasons, the importance of prevention must be stressed to prevent our dog from becoming infested.

In the market there are several products that can be used for this purpose. They are usually from monthly application and begin to be used one month before the maximum risk period and its use is prolonged up to one month after this interval. These drugs usually prevent the development of larvae.

It will be ours vet who guides us on the best preventive options according to the area in which we live. It is important to maintain precautions throughout the dog's life. In areas with high presence of filarias it would be advisable take a test to check if the dog is infested or not before starting prophylaxis. The ideal prevention would also include mosquito control, since they are the ones that transmit the parasites. Although this aspect is impossible, we can follow some preventive measures such as avoiding walks late in the afternoon or at night, since that is when the mosquitoes will feed.

If the dog lives outside it is advisable to close it during the months of greatest risk of bites. You can also avoid the breeding areas of these mosquitoes, eliminate standing water or use a repellent product. Do not forget deworming externally and internally your dogs and, if you consider it convenient, also use a homemade mosquito repellent for dogs.

Is filaria in dogs contagious?

As we have seen, filaria in dogs need the intermediation of a mosquito to develop This means that a dog cannot, by itself, infect another. On the other hand, if there is a chance that an infested dog is bitten by a mosquito and this, in turn, bites another dog just having the infectious filariae in its mouth organs, this second dog yes it could be infected.

In that case the first dog would have functioned as a reservoir. In such a situation human infection rarely occurs. For all this it is essential to prevent and treat affected dogs, to avoid creating reservoirs.

This article is purely informative, at we have no power to prescribe veterinary treatments or make any kind of diagnosis. We invite you to take your pet to the veterinarian in case he presents any type of condition or discomfort.

If you want to read more articles similar to Filaria in dogs - Symptoms and treatment, we recommend that you enter our section of parasitic diseases.

What are the symptoms?

One of the problems of this disease is that, when we notice symptoms in the dog, it has been a long time. Therefore, we must always be aware of any small changes that occur in your routine or behavior. Symptoms such as:

  • Lack of appetite
  • Soft cough, which seems not to be relieved
  • Fatigue
  • General discomfort
  • Breathing acceleration

Can it be treated?

Fortunately, yes. But the treatment will vary according to the case. If it has been detected in time and only has larvae, the veterinarian will recommend giving you some antiparasitic tablets and injections to recover, otherwise, you will choose to operate it in order to remove all the filarias.

How to prevent canine filariosis?

Preventing this disease is very simple: it will only be necessary to take the dog to the vet for a blood test, and, if he is healthy, we will have to give him an antiparasitic pill a month to avoid parasitic infections.

Canine filariosis is a disease that can be treated. Do not let it pass.