SURGICAL INTERVENTION IN CANINE HEARTWORM. LITERATURE REVIEW

In Brazil, surgical intervention in the treatment of dogs heavily infected by Dirofilaria nematode is an uncommon procedure. This is a technique where mechanical removal of the parasite is performed using plenty kinds of recovery tweezers. Removing Dirofilaria using recovery devices, such as grasping forceps, is an efficient and safe therapeutic alternative for treating dogs with a high load of this worm.


INTRODUCTION
Preventive action is a priority for veterinarians, as this becomes the main key to give a good quality of life for domestic animals as well as for the whole society where they are inserted (FURTADO et al., 2018). Still, cases such as heartworm disease, which is a silent pathology, often, after the pathogen is already very established in the host, requires more specialized medical procedures (SALGUEIRO, 2016).
Heartworm disease is the name of a serious disease that can be fatal, affecting mainly dogs, but can also occur in cats and other wild animals. In this disease, adult helminths live in the heart and pulmonary arteries and can cause heart failure and severe lung disease, leading the animal to death (ATKINS, 2004).

TRANSMISOR AGENT
The disease is transmitted by several species of mosquitoes, which act as mandatory intermediate hosts (NELSON;COUTO, 2010), of which about 70 species of the genera Aedes, Anopheles and Culex are known, which may be potential vectors of the parasite, but the vector transmission capacity has been proven only in 12 species (SALGUEIRO, 2016).
It was observed that the population with the highest risk of infection is composed of dogs that are more exposed to the bite of transmitting mosquitoes, in example those that do not have a permanent shelter, hunting dogs, dogs living in rural areas, grazing dogs, in addition to outdoor competition dogs and those that are transported to endemic areas (TZIPORY; CRAWFORD; LEVY, 2010).
When the transmitting agent performs blood repast in mammals (dogs, humans, cats, among others) the disease can be disseminated, a situation that occurs by the action of young microfilariae, which are transmitted through the mouthpiece of the transmitting agent (ATKINS, 2004).

HEART'S MICROFILARIA
Once installed in the heart, these parasites lead to important changes in the heart, veins and arteries. These can be diagnosed with the aid of a serological test (rapid blood test), by an echocardiogram test or visualization of microfilariae in blood smear (ATKINS, 2004). Once heartworm disease is detected in dogs, one of the contemplated treatments is surgical intervention, which is still little performed in Brazil (DELLING, 2019).
Some dogs that are infected by heartworm disease may develop serious complications due to adult worms that become clogging the blood flow of the heart valves. This situation Environ. Smoke FURTADO;MENDES;FARIAS v. 3, n. 2, 2020 88 can trigger very severe congestion in the hepatic system, systolic murmur of tricuspid valve regurgitation, and it is possible to observe pulsations in the jugulars. As indicators of this pathology, it is also observed that the animal presents lethargy, dyspnea, membranes and pale mucosa, weakness accompanied by hemoglobinemia and hemoglobinuria (ATWELL; LITISTER, 2002;VENCO, 1993). These symptoms, if untreated, will cause the dog to die.
One technique that can be used is the removal of worms through surgery (DELLING, 2019).

SURGICAL INTERVENTION
This surgery consists of the removal of the worms from the heart, but appropriately, from the atrium and orifice of the tricuspid valve. The most common approach is right jugular venotomy in the left lateral decubitus in order to remove adult parasites through an incision in the jugular vein (NELSON; COUTO, 2010).
This, according to the techniques applied in other countries, they can be performed by means of a slight sedation and/or local anesthesia, which will allow the use of flexible tweezers, such as long alligator tweezers or basket seizure clamp or tripod grip clamp, and proceed with the introduction of this, preferably, through the right external jugular vein (YOON et al., 2013).
Using a radioscopy, will give greater safety to the procedure, the long alligator Another technique that has been used in very small dogs is the right ear cannulation performed through thoracotomy, for removal of worms (NELSON; COUTO, 2010).
Since the surgical intervention is well developed, the patient should present the heart murmur softened or null, and after 24 hours hemoglobinuria must have disappeared (ALHO et al., 2016). ;MENDES;FARIAS v. 3, n. 2, 2020 89 The patient, after a successful intervention, should be ascertained to assess the presence of some worm still present in the heart. If a few parasites are still observed, "adulticide" treatment should be carried out to eliminate the heartworm still present (ALHO et al., 2016).

FURTADO
It was observed that the postoperative survival rate was efficient, presenting a result without statistical differentiation, but several complications associated with the intervention of removal of dirofilariasis were reported in the recovery devices used in the study of Yoon and collaborators (YOON et al., 2013).

CONCLUSIONS
Considering the information and data obtained in the studies, it is suggested that the removal of heartworm disease through surgical intervention is a therapeutic method that imprints relative safety and presents itself as a safe measure to be applied to canine patients with a large worm load, presenting a good survival rate, although it still requires further studies directed to this surgical technique (ALHO et al., 2016).