ESDA Invited Speakers

Roger Prichard
Distinguished James McGill Professor Emeritus,McGill University,
Canada

MACROCYCLIC LACTONE RESISTANCE IN DIROFILARIA IMMITIS : RISK FOR EUROPE?

Prichard RK¹.
¹Institute of Parasitology, McGill University, Montreal, Canada
roger.prichard@mcgill.ca

Keywords: Dirofilaria immitis, heartworm preventives, macrocyclic lactone resistance, resistance monitoring, resistance spread

Heartworm disease, caused by Dirofilaria immitis, can result in severe morbidity and death, particularly in dogs, due to cardiovascular pathology. It can also cause disease in cats and can be zoonotic. The infective stage L3 larvae are transmitted by many species of mosquitoes. The parasite has an almost global prevalence, wherever there are mosquitoes and enough warm days for the parasite to develop in the vector. Transmission is often seasonal. Global warming, with resultant wider distribution and intensity of mosquito transmission, and larval development (warm) days, may increased the risk of heartworm infection and disease.

Once infected and adult worms develop in dogs with resultant pathology and potential for transmission. Parasites can persist for years. Adult worms may be removed with arsenicals. However, there is some risk associated with clinical treatment, and it is expensive. Because of the expense, some infected dogs are not treated, and they can be the source of infection to other hosts via the mosquito vector. Other dogs are treated with a ‘slow-kill’ approach involving prolonged administration of macrocyclic lactones (MLs) and doxycycline. For ‘slow-kill’, treatment for about a year is required to remove all worms and it has not been recommended because of the concern for selection of drug resistance. The main control is prevention with macrocyclic lactone preventives which kill the L3/L4 stages prior to the pathogenic adults establishing. However, resistance to MLs has developed in the USA. Despite intensive campaigns for year-round prevention in the USA, we see that the incidence of heartworm infection has increased dramatically over the past 25 years, according to the American Heartworm Society. The question arises as to whether this increased incidence in the USA is due to better monitoring, or to other factors such as lower compliance with prevention despite a relentless campaign to use preventives, a dramatic increase in vector activity, or a loss in efficacy of MLs due to selection for drug resistance? Loss of efficacy of ML preventives was first noted in 2005 (Hampshire, 2005), and a first confirmed case of ML-resistance was reported in 2011 in a dog imported into Canada from Louisiana, USA (Bourguinat et al., 2011).

Genetic (SNP – single nucleotide polymorphic) markers have been developed to monitor for genotypic evidence of ML-resistance in D. immitis (Bourguinat et al., 2015; Ballesteros et al., 2018; Kumar et al., 2023) and have been used in several small and large surveys for resistance to ML heartworm preventives in the USA. In addition, the microfilariae suppression test (MFST), as well as the use of experimental infections while animals have been under heartworm preventive regimes, have been used to confirm phenotypic resistance. In addition, information on compliance with heartworm prevention has been gathered. These numerous studies in the USA now show that ML-resistance is widespread and can reach alarming levels in some locations (Fisher, Keller, Prichard, 2024; Curry et al., submitted). This indicates a serious breakdown in containing heartworm disease in the USA, and the potential for resistance to spread to new regions/countries with the possible transport of infected dogs, not to mention vector movement and spread aided by climate change.

What is the situation outside the USA? A study in eastern Australia (Queensland and NSW) showed no evidence of genotypic or phenotypic resistance to ML-preventives in 45 heartworm infected dogs (Power, Slapeta, 2022). We conducted a limited survey, in 2015-2016, in heartworm infected dogs from southern Ontario, Canada and found genotypic markers for ML-resistance in 3 of 39 D. immitis samples (Engell et al., in preparation).

Heartworm infections appear to be spreading in Europe. Culex pipiens, C. theileri, Aedes albopictus, Ae. caspius, Ae. vexans, Anopheles maculipennis, Coquilletidia richiardii are found in Europe and can transmit D. immitis if there are sufficient days (8 to 24 days, depending on temperature) with suitable parasite development conditions (temperatures above 14°C) (Morchón et al., 2012). There is evidence for the spread of mosquitoes of the genus Aedes in Europe. Furthermore, both published data, and data collected for myVBDmap™, from clinics indicate a spread of heartworm infections to regions not previously considered endemic for D. immitis, such as Germany, and possible increase in incidence of heartworm infections in Europe. We have conducted two limited surveys, based on the SNP markers for ML-resistance, in heartworm infected dogs in 5 countries in Europe. These surveys suggested that ML-resistance either was not yet present in Europe or only occurred infrequently. However, it must be considered that very little monitoring for ML-resistance is occurring, so far in Europe and other countries outside of the USA. Nevertheless, my colleagues have recently reported a case of both genotypic and phenotypic evidence of ML-resistance in a dog treated in Italy (Traversa et al., 2024). Some months before the resistant infection was detected, the dog had been transported from the USA to Italy and although the dog had been checked for heartworm (antigen test) before being transported, it is possible that the ML-resistant heartworms were imported with the dog. Nevertheless, this shows the risk of ML-resistance being introduced when animals are transported and possibly establishing resistant foci in Europe and other regions.

It is time to discuss how we can reduce the risk of spreading ML-resistance in D. immitis and what can be done to maintain heartworm prevention in the face of spreading ML-resistance. These steps include more monitoring for resistance, paying particular attention to animals that are transported to new locations, and the use of the most effective preventive regimes. The latter involves the choice of ML used, dose rate, route of administration and full prevention compliance during periods when mosquitoes may acquire and transmit the parasite. Further steps are needed to reduce mosquito transmission of D. immitis in general, and particularly in the case of vectors which may acquire a resistant infection. Optimally this involves using medications with high potency against developing stages of D. immitis, including strains that show evidence of resistance to less potent ML formulations, but also preventive combinations with ectoparasiticides which prevent mosquito reproduction and/or repel mosquitoes during the interval between preventive administration. Finally, novel heartworm preventives which are not affected by ML-resistance, and are safe and convenient to administer, are needed.

References

Hampshire VA. Evaluation of efficacy of heartworm preventive products at the FDA. Vet Parasitol. 2005;133:191–5.
Bourguinat C, Keller K, Bhan A, Peregrine AS, Geary TG, Prichard RK. Macrocyclic lactone resistance in Dirofilaria immitis. Vet Parasitol. 2011;181:388–92.
Bourguinat C, Lee ACY, Lizundia R, Blagburn BL, Liotta JL, Kraus MC, Keller K, Epe C, Letourneau L, Kleinman CL, Paterson T, Carreton Gomez E, Montoya-Alonso JA, Smith H, Bhan A, Peregrine AS, Carmichael J, Drake J, Schenker R, Kaminsky R, Bowman DD, Geary TG, Prichard RK. Macrocyclic lactone resistance in Dirofilaria immitis: Failure of heartworm preventives and investigation of genetic markers for resistance. Parasitol. 2015;210:167-78.
Ballesteros C, Pulaski C, Bourguinat C, Keller K, Prichard RK, Geary TG. Clinical validation of molecular markers of macrocyclic lactone resistance in Dirofilaria immitis. Int J Parasitol Drugs Drug Resist. 2018;8(3):596-606.
Kumar S, Prichard RK, Long T. Droplet digital PCR as a tool to detect resistant isolates of Dirofilaria immitis. Int J Parasitol Drugs Drug Resist. 2023;23:10–8.
Fisher PT, Keller K, Prichard RK. Investigating Dirofilaria immitis isolates infecting domestic canines and their susceptibility/resistance patterns to macrocyclic lactones in the northern region of the Mississippi Delta area (southeast Missouri). Vet Parasitol. 2024;329:110199.
Curry E, Tack D, Rodriguez J, Brehm-Lowe D, Lineberry M, Prichard R, Clark T. Surveillance of single nucleotide polymorphisms correlated to macrocyclic lactone resistance in Dirofilaria immitis from client-owned dogs across the United States. Int J Parasitol:Drugs Drug Resist. 2025;submitted.
Morchón R, Carretón E, González-Miguel J, Mellado-Hernández I. Heartworm disease (Dirofilaria immitis) and their vectors in Europe – new distribution trends. Frontiers Physiol. 2012;3: doi: 10.3389/fphys.2012.00196.
Traversa D, Diakou A, Colombo M, Kumar S, Long T, Chaintoutis SC, Venco L, Miller GB, Prichard R. First case of macrocyclic lactone-resistant Dirofilaria immitis in Europe - Cause for concern. Int J Parasitol Drugs Drug Resist. 2024;25:100549.

Jorge Guerrero
Adjunct Full Professor of Parasitology, University of Pennsylvania (1983-2018), USA

The history of heartworm prevention - Macrocyclic lactones. A personal perspective.

Jorge Guerrero
DVM, MSc, PhD, Dipl.ACVM, Dipl.EVPC (retired)
Former Adjunct Professor of Parasitology, School of Veterinary Medicine, University of Pennsylvania, PA, USA
Retired Executive Director, Merck and Co, Inc, Rahway, NJ USA

Introduction

Heartworm disease, caused by the parasitic nematode Dirofilaria immitis, poses a significant threat to the health of dogs and cats worldwide. The prevention of this disease has undergone substantial advancements over the past 40 years, particularly with the development of the macrocyclic lactones. These compounds revolutionized heartworm prevention, offering pet owners effective and practical ways to protect their pets from this potentially fatal condition.

Early Research and Discoveries

My journey towards getting involved with heartworm started as I was transferred in 1977 from J&J Brazil to their animal health division Pitman Moore, Inc in the USA. The state of the art that time was the preventive DEC a tablet used daily. As a microfilaricide the focus was in looking for a replacement of dithiazanine iodide. At that time early efforts in heartworm management and prevention focused on compounds such as Levamisole (LVS), which was also researched extensively for its potential use as an immunomodulator.

Initial Developments

In the late 1970s, significant progress was made in the field of heartworm research by researchers like Drs. Ron Jackson and John McCall who were at the forefront of these developments. Their collaborations with institutions like the University of Georgia and the Merck Institute for Therapeutic Research laid the groundwork for future breakthroughs.

Initial Milestones

One of the pivotal moments in the development of heartworm preventatives was the presentations of research findings at the second American Heartworm Symposium held in Atlanta, Georgia in 1977. This gathering provided a platform for scientists to share their work and foster collaborations. As at the time I had done work with Levamisole as an immunomodulator I was asked to present a review at the AHS Symposium. After my presentation Dr. David Knight requested my collaboration supplying LVS tablets to study further their effect on microfilariae.

The Introduction of Macrocyclic Lactones

Macrocyclic lactones, a group of compounds derived from soil microorganisms, emerged as a game-changer in heartworm prevention. These compounds, which include ivermectin, milbemycin oxime, selamectin and moxidectin, exhibited remarkable efficacy in preventing heartworm infections in both dogs and cats.

Ivermectin

Ivermectin, the first macrocyclic lactones to be introduced, quickly gained recognition for its potent antiparasitic properties. Initially used in livestock, ivermectin's application expanded to companion animals, offering a reliable means of heartworm prevention. Its monthly administration schedule provided convenience and assurance to pet owners.

Milbemycin Oxime, Selamectin and Moxidectin

Following the success of ivermectin, other macrocyclic lactones like milbemycin oxime and moxidectin were developed. Milbemycin oxime, known for its broad spectrum of activity against various parasites, became a popular choice for heartworm prevention. Moxidectin, with its extended duration of efficacy, further enhanced the options available to veterinarians and pet owners. Selamectin was introduced as a long-acting injectable formulation in the nineties.

Development Challenges and Innovations

The development of macrocyclic lactones was not without its challenges. Researchers of Merck Sharp and Dohme Research Laboratories (MSDRL) faced hurdles in formulating these compounds into effective and safe products in view of the minute amounts of active principle used. Also, surprisingly some breeds of dog (e.g., collies, sheepdogs, and collie- or sheepdog-crosses) were found to be more sensitive to ivermectin than others. This is typically due to a genetic mutation (MDR1) that makes them less able to tolerate high doses of ivermectin (over 50mcg/Kg). If used at the prescribed dose (6mcg/Kg) for heartworm prevention, ivermectin is safe for MDR1 dogs. At the dose selected as a preventive of heartworm, it did not show any lethal effects on other nematodes. However, these challenges spurred innovation and led to the refinement of formulations that ensured both efficacy and safety.

Diagnostic Advancements

Concurrently with the development of macrocyclic lactones, advancements in diagnostic tools played a crucial role in heartworm prevention. Products like Filarassay C and F, developed by Pitman Moore, Inc, provided accurate and reliable means of detecting heartworm infections in the seventies. However, the great advance was the development of ELISA based kits for detection of circulating adult antigens. These diagnostic innovations complemented preventative measures, enabling timely interventions and improved outcomes for affected animals.

Impact and Future Directions

The introduction of macrocyclic lactones marked a significant turning point in the fight against heartworm disease. These compounds not only offered effective prevention but also contributed to the overall health and well-being of companion animals. The ongoing research and development in this field continue to refine and enhance heartworm prevention strategies.

Current Trends

In recent years, the focus has shifted towards developing novel formulations and delivery methods to improve compliance and efficacy. Innovations such as long acting injectables and combination products that target multiple parasites are gaining traction. Additionally, the integration of advanced diagnostics and monitoring tools is further enhancing the ability to prevent and manage heartworm infections.

Prospects

Looking ahead, the future of heartworm prevention holds promise with ongoing research into combined products, new compounds and technologies. The goal remains to provide safe, effective, and convenient solutions that ensure the well-being of dogs and cats worldwide. Collaborative efforts between researchers, clinical veterinarians, and pharmaceutical companies will continue to drive advancements in this critical area of veterinary medicine. However, we must keep in mind that the development of any new molecule is very costly (2.6 billion US dollars), therefore we have to use and preserve our present compounds with care and outmost responsibility.

Conclusion

The development of macrocyclic lactones for heartworm prevention in dogs and cats represents a remarkable achievement in veterinary medicine. From the early research and discoveries to the introduction of a variety of groundbreaking compounds like ivermectin, milbemycin oxime, selamectin and moxidectin, the journey has been marked by innovation, collaboration, and a steadfast commitment to animal health. As we move forward, continued advancements in this field will undoubtedly contribute to the ongoing efforts to protect our beloved pets from the threat of heartworm disease.

Laura Kramer
Full Professor of Veterinary Parasitology and Parasitic Diseases, University of Parma Veterinary School, Italy

HISTORY OF WOLBACHIA AND HEARTWORM: A SYMBIOTIC SAGA OF TINY GUESTS AND THEIR WORMY HOSTS.

Kramer L.
Department of Veterinary Sciences, University of Parma, Strada del Taglio 10, 43126 Parma Italy
laurahelen.kramer@unipr.it

Keywords: Wolbachia, Dirofilaria immitis, history

Introduction. Wolbachia is the most widespread endosymbiont in animals. It was discovered in arthropods nearly 100 years ago. Since then, it has been the object of over 4,000 scientific publications, including studies on host tropism, co-evolution, genomics and implications for human and animal health. Wolbachia is indeed an amazing microorganism that has changed the way we understand the world of heartworm disease, in particular pathogenesis, immunology and treatment. Here, we will go back in time and unravel the fascinating story of Wolbachia and Dirofilaria immitis.

How it all began. If you ask any researcher who studies endosymbiosis in filarial nematodes (and there are many!), they will likely say that it all began in 1995, when colleagues from the universities of Milan and Pavia (Italy) published the study entitled “Molecular evidence for a close relative of the arthropod endosymbiont Wolbachia in a filarial worm” (Sironi et al., 1995). Even though intracellular bacteria had been seen in filarial nematodes with electron microscopy in the ‘70s (McClaren et al., 1975), nobody knew what they were, who they were or why they were there. There had also been a couple of published studies on the anti-filarial effects of tetracycline, but no one thought about those tiny bacteria, thinking rather that the antibiotic had some sort of direct effect on the worms. Many years later, Sironi and colleagues gave these bacteria a name, and by doing so, opened the door to a whole new filarial world. This fundamental discovery was thanks to their curiosity, intuition and experience in the field of endosymbiosis.

What we know. As soon as Sironi and colleagues described Wolbachia in heartworms, a flurry of excitement went through the scientific community. Subsequent research was aimed at looking for other filarial nematodes that harbored the bacteria and at defining the nature of the Wolbachia-filarial nematode relationship. Wolbachia was described in a further nine species of animal and human filarial nematodes by 1999. Results of further studies were highly suggestive that Wolbachia are obligatory mutualist symbionts because: i) every individual of every filarial species known to harbor Wolbachia, harbors Wolbachia (100% prevalence); ii) the two organisms have evolved together for millions of years (matching evolution); iii) Wolbachia is transmitted vertically from female worms to microfilariae; iv) elimination of Wolbachia is detrimental for the worm. Indeed, by the year 2000, several authors had reported that the anti-filarial effects of tetracycline observed 25 years before were due to the depletion/elimination of Wolbachia, and the focus of subsequent research became the targeting of Wolbachia for the treatment of human and animal filarial diseases. Studies on the effects of antibiotic treatment on Dirofilaria immitis-infected dogs (with doxycycline) reported that bacterial depletion from adult worms, elimination of microfilariae and adult worm death were all more efficient when antibiotics were combined with macrocyclic lactones (MLs; Bazzocchi et al., 2008) and that this combination also reduced the potentially severe post-adulticide effects of melarsomine (Kramer et al., 2008). We also learned that D. immitis-infected dogs mount an immune response to Wolbachia, likely through exposure to dead or dying parasites, and that Wolbachia contributes to the immunopathology of heartworm disease (Kramer et al., 2005; Diosdado et al., 2017). Some insights on what exactly Wolbachia and Dirofilaria spp. do for each other were also gained when, in 2012, genome sequencing of D. immitis and its Wolbachia was completed (Godel et al., 2012). Wolbachia are unable to synthetize several vitamins and cofactors (coenzyme A, biotin, folate), making them metabolically dependent on the D. immitis host. On the other hand, the known effects of elimination of Wolbachia from D. immitis (loss of fertility and vitality of adult filarial worms) are likely due to a lack of pathways for the synthesis of heme, purine and pyrimidine in Dirofilaria, which are however present in Wolbachia.

What we do not know. Even though Wolbachia has been identified in Dirofilaria repens (Grandi et al., 2008), we do not know what role it plays in the pathogenesis of subcutaneous dirofilariosis nor if doxycycline/ML combinations are adulticidal. We also do not know if these combinations are effective for treating feline heartworm disease. Finally, there is some recent evidence that Wolbachia from ML-resistant D. immitis are slightly different than Wolbachia from susceptible worms (Shin et al., 2020), suggesting that the Wolbachia genome may be able to evolve in response to selection pressures, including the use of antibiotics.

Conclusions. All of the ground-breaking studies cited here confirm that targeting Wolbachia is a winning strategy against heartworm disease, and this has led inevitably to the revision of international guidelines for the treatment of infection. There is still much to do, and it must be remembered that curiosity and intuition are and always will be the most important keys to research success!

References

Bazzocchi C, Mortarino M, Grandi G, Kramer LH, Genchi C, Bandi C, Genchi M, Sacchi L, McCall JW. Combined ivermectin and doxycycline treatment has microfilaricidal and adulticidal activity against Dirofilaria immitis in experimentally infected dogs. Int J Parasitol. 2008; 38(12):1401-10.

Diosdado A, Gómez PJ, Morchón R, Simón F, González-Miguel J.Interaction between Wolbachia and the fibrinolytic system as a possible pathological mechanism in cardiopulmonary dirofilariosis. Vet Parasitol. 2017; 247:64-69

Grandi G, Morchon R, Kramer L, Kartashev V, Simon F. Wolbachia in Dirofilaria repens, an agent causing human subcutaneous dirofilariasis. J Parasitol. 2008; 94(6):1421-3

Godel, C., Kumar, S., Koutsovoulos, G., Ludin, P., Nilsson, D., Comandatore, F., Wrobel, N., Thompson, M., Schmid, C. D., Goto, S., Bringaud, F., Wolstenholme, A., Bandi, C., Epe, C., Kaminsky, R., Blaxter, M., Mäser, P. The genome of the heartworm, Dirofilaria immitis, reveals drug and vaccine targets. FASEB J. 2012; 26: 4650–466

Kramer LH, Tamarozzi F, Morchón R, López-Belmonte J, Marcos-Atxutegi C, Martín-Pacho R, Simón F. Immune response to and tissue localization of the Wolbachia surface protein (WSP) in dogs with natural heartworm (Dirofilaria immitis) infection. Vet Immunol Immunopathol. 2005;106(3-4):303-8

Kramer L, Grandi G, Leoni M, Passeri B, McCall J, Genchi C, Mortarino M, Bazzocchi C. Wolbachia and its influence on the pathology and immunology of Dirofilaria immitis infection. Vet Parasitol. 2008;158(3):191-5

McLaren, D.J., Worms, M.J., Laurence, B.R. and Simpson, M.G. (1975) Micro-organisms in filarial larvae (Nematoda). Trans. R. Sot. Trop. Med. Hyg. 69, 509-514.

Sironi M, Bandi C, Sacchi L, Di Sacco B, Damiani G, Genchi C.Mol Biochem Parasitol. Molecular evidence for a close relative of the arthropod endosymbiont Wolbachia in a filarial worm. 1995;74(2):223-7

Shin PT, Baptista RP, O'Neill CM, Wallis C, Reaves BJ, Wolstenholme AJ. Comparative sequences of the Wolbachia genomes of drug-sensitive and resistant isolates of Dirofilaria immitis. Vet Parasitol. 2020;286

Andy Moorhead
Small animal Parasitologist, Associate Professor, North Carolina State University, College of Veterinary Medicine, USA

American Heartworm Guideline updates: what we kept and what we changed and why
*online presentation

Andy Moorhead
Department of Clinical Sciences, College of Veterinary Medicine, North Carolina State University, Raleigh, NC, USA

The American Heartworm Society (AHS) periodically revises their guidelines for diagnosis and treatment of canine heartworm. The most recent update included a comprehensive review of the literature. While many aspects of the guidelines remained the same, information about the expanding number and range of mosquito intermediate hosts was updated. This presentation will focus on two key recommendations with regards to diagnosis and treatment. For diagnosis, both testing for adult female uterine antigen, using a commercially available test, and microfilariae are recommended. The reason for this is that immune complexing of parasite antigens and host antibodies has been documented and can result in false negative antigen tests. By checking for microfilariae by either visual or molecular methods, we will have a greater chance of diagnosing positive animals, even when antigen tests are false negative because of immune complex formation. We can confirm a positive microfilariae result in these cases by “heat-treating” serum, thus breaking antigen/antibody complexes. The now “free” antigen will now be available to bind with the antibodies on the testing platform. The second recommendation is regarding treatment and the 30-day period between the end of doxycycline administration and the beginning of melarsomine dihydrochloride injections. The AHS recommended treatment for heartworm includes consistent administration of a macrocyclic lactone preventive, 28 days of doxycycline at a dose of 10 mg/kg BID for Wolbachia, followed by a 30-day period. At the end of this period one injection of melarsomine is given, followed 30 days later by two injections 24 hours apart. The need for the 30-day period between the end of doxycycline and beginning of melarsomine has been debated on the basis that there may be an increase in the pathologic changes in the host associated with heartworm during this time. Recent research has shown that there are no further pathologic changes during this period and furthermore that the amount of Wolbachia present in adult worms is reduced to almost zero. Since the presence of has been associated with increased clinical signs secondary to pulmonary thromboembolism, a greater reduction of Wolbachia prior to melarsomine treatment is considered beneficial to the animal.

Marisa Ames
Associate Professor of Cardiology, University of California, Davis School of Veterinary Medicine, USA

Management of symptomatic heartworm disease in dogs

Marisa K. Ames
DVM, DACVIM (Cardiology)
UC Davis School of Veterinary Medicine; University of California, Davis, USA

Abstract

Most dogs diagnosed with heartworm disease (HWD) do not have clinical sigs (or have only mild signs such as intermittent cough) and go through adulticide therapy without complication. Clinical signs usually reflect the pulmonary vascular and parenchymal injury caused by Dirofilaria immitis. This lecture will review several clinical presentations of HWD and discuss therapy. (Table 1). Note: A uniform treatment recommendation for all conditions below is activity restriction.

Table 1. Approach to the symptomatic heartworm patient

Condition & Signs

Time of Onset and Comments

Treatment

Pneumonitis

Cough, tachypnea, dyspnea

-Timing varies

-Associated with death of Mf or presence/death of adult worms

-Radiographic findings: perivascular inflammatory bronchial and/or interstitial infiltrates

-Note: this is not cardiogenic edema and furosemide is not indicated

-Oxygen

-Dexamethasone (0.2 mg/kg, IV)

-Oral corticosteroids (0.5 mg/kg PO q12h, tapered as clinical signs allow)

HW-associated thrombosis/PTE

Tachypnea, dyspnea, cyanosis, collapse, cough, hemoptysis

-Timing varies

-May occur spontaneously at any time; risk likely greatest 3-21 days after melarsomine administration (peak worm death)

-Injury/death of worms leads to thrombosis

-Risk of severe thrombotic event increases with exercise or rapid worm kill (2-dose melarsomine protocol)

-Oxygen

-Sildenafil (1 to 2 mg/kg PO q8h)

-Corticosteroid therapy, route, and agent determined by severity and patient’s need for rapid treatment

Right-sided CHF

Abdominal distension, jugular distention, tachypnea, dyspnea, weight loss

-Usually associated with chronic, untreated HWD

-Pulmonary hypertension often present

-Can initiate ‘run-in’ to adulticide therapy at the time of diagnosis (preventive and doxycycline)

-Melarsomine should not be started until the dog’s CHF is medically controlled

-Furosemide (‘at home’ dose typically 1 to 3 mg/kg PO q12h)

-Pimobendan (0.25 mg/kg PO q12h)

-Sildenafil (1 to 2 mg/kg PO q8h)

-Spironolactone (2 mg/kg PO q24h)

-Centesis

-Therapy can sometimes be reduced or discontinued after successful HW treatment

Caval syndrome

Pallor, murmur, pigmenturia, collapse Signs of low cardiac output ± right-sided CHF

-Usually associated with chronic, untreated HWD or when a very large worm burden matures simultaneously

-Can initiate ‘run-in’ to adulticide therapy at the time of diagnosis (preventive and doxycycline)

-Melarsomine should not be started until the dog is stable

-Stabilization: fluid resuscitation, ± vasopressors, ± blood products to normalize coagulopathy

-Heavy sedation or general anesthesia, jugular venotomy, and worm extraction with forceps^a, gooseneck snare, or endovascular snare

-Prompt HW removal is ideal (if not possible, can try oxygen therapy, pimobendan, and sildenafil)

-See above for therapy of R-CHF

CHF, congestive heart failure; HW, heartworm; HWD, heartworm disease; PTE, pulmonary thromboembolism; Mf, microfilaria; ^aAvalon Medical, ClearIt® Heartworm Removal Device, Stillwater, MN 55082, USA

Donato Traversa
Full Professor of Veterinary Parasitology and Parasitic Diseases of Animals, Department of Veterinary Medicine, University of Teramo, Italy

Simona Gabrielli
Associate Professor of Parasitology and Parasitic Diseases, University of Rome Sapienza, Italy

FROM DOGS TO HUMANS: THE GROWING CHALLENGE OF DIROFILARIOSIS

Gabrielli, S.
Department of Public Health and Infectious Diseases, Sapienza University of Rome, Rome, Italy
simona.gabrielli@uniroma1.it

Keywords: Human dirofilariosis; Diagnosis; Clinical presentation.

Dirofilariosis, an infectious disease caused by filarial nematodes of the genus Dirofilaria, is transmitted to humans through the bite of infected mosquitoes from the genera Aedes/Ochlerotatus, Anopheles, and Culex. Conventionally, dirofilariosis has been regarded as a disease affecting domestic and wild canines and felines, as well as various other carnivores. However, recent evidence suggests that it is now emerging as a zoonotic infection, with an increasing incidence in humans.

Among the various species, Dirofilaria immitis and Dirofilaria repens are of particular concern in terms of their clinical impact on humans and animals. Recent epidemiological data indicate their spreading beyond its traditional endemic zones in southern Europe, parts of Asia, and the Americas. Factors contributing to this trend include climate change—extending the active seasons and habitats of mosquito vectors—along with increased international pet travel and relocation. Surveillance studies indicate a steady increase in canine prevalence in northern and central Europe, correlating with the emergence of human cases in previously unaffected regions (1).

From a clinical perspective, D. immitis primarily causes cardiopulmonary disease in canines, while D. repens is typically responsible for subcutaneous and ocular infections. In humans, dirofilariosis frequently manifests as benign subcutaneous nodules, ocular infections (particularly in the periorbital region), or pulmonary "coin lesions" that may resemble neoplasms, occasionally resulting in unwarranted invasive procedures. Furthermore, there is a paucity of literature concerning unusual localisations in the brain, testis, breast or other uncommon sites. This complicates diagnosis due to the absence of specific symptoms and the unfamiliarity of such cases among clinicians (2).

The definitive diagnosis typically relies on histopathological examination following surgical removal of the lesion or worm. Imaging techniques like CT and MRI can help identify nodular lesions, but diagnosis is often delayed due to nonspecific symptoms and the rarity of human cases. Molecular and immunological tests are available to supplement or replace traditional morphology-based diagnostics, and experimental ELISAs have been developed for human serology, though they are not yet widely used in clinical practice.

Despite humans have long been considered accidental, “dead-end” hosts, since parasites do not generally reach reproductive maturity in human tissue, there have now been almost 27 documented cases of human infections involving gravid D. repens females. This finding suggests the possibility of male and female worms maturing in the human host, thereby challenging the long-standing assumption that humans are incapable of supporting the full life cycle of such worms. In contrast, only one case of human D. immitis infection with a female worm has been documented, and the patient was found to have acute lymphoblastic leukaemia and an immune system compromised by the disease. It is important to note that there are several other non-canine species that have the potential to infect humans. These include D. tenuis (transmitted from raccoons), D. ursi (transmitted from American black bears), D. subdermata (transmitted from North American porcupines), D. spectans (transmitted from Brazilian otters), and D. striata (transmitted from bobcats) which should be considered in differential diagnosis with other possible human filarial infections (3).

The growing zoonotic potential of dirofilariosis calls for enhanced awareness among clinicians, veterinarians, and public health authorities. Strengthening vector surveillance, improving diagnostic protocols, and promoting preventive measures such as canine prophylaxis and mosquito control are crucial. This presentation will advocate for the adoption of a One Health approach to address the evolving landscape of dirofilariosis, emphasizing interdisciplinary collaboration to mitigate its impact on both animal and human health.

References

1. Genchi C, Kramer LH, Rivasi F. Dirofilarial infections in Europe. Vector Borne Zoonotic Dis. 2011 Oct;11(10):1307-17.

2. Simón F, Diosdado A, Siles-Lucas M, Kartashev V, González-Miguel J. Human dirofilariosis in the 21st century: A scoping review of clinical cases reported in the literature. Transbound Emerg Dis. 2022 Sep;69(5):2424-2439.

3. Momčilović S, Jovanović A, Gasser RB. Human dirofilariasis - A potentially significant nematode zoonosis in an era of climate change. J Infect. 2025 Apr;90(4):106460.

Rodrigo Morchón García
Full Professor and director of the Zoonosic Diseases and One Health research group, University of Salamanca, Spain

Ecological niche modeling and vector Dirofilaria spp. sharing as tools to assess the risk of Dirofilaria infection in Europe

Morchón R.^1,2,3, Rodríguez-Escolar I.^1,2, Balmori-de la Puente A.^1,2, Collado-Cuadrado M.^1,2, Infante González-Mohino E.^1,2, Montoya-Alonso J. A.^1,3, Carretón E.^1,3

¹Zoonotic Diseases and One Health GIR, Faculty of Pharmacy, University of Salamanca, Spain.

²Biomedical Research Institute of Salamanca (IBSAL), Centro de Estudios Ambientales y Dinamización Rural (CEADIR), University of Salamanca, Spain.

³Internal Medicine, Faculty of Veterinary Medicine, Research Institute of Biomedical and Health Sciences, University of Las Palmas de Gran Canaria, Spain.

Keywords: Heartworm disease, Culex pipiens, Aedes albopictus, Ecological Niche Model, Europe.

In Europe, Dirofilaria infection is of significant veterinary and economic importance due to its impact on the health and welfare of both domestic and wild animals, primarily canids and felids. The presence of Dirofilaria immitis and D. repens is influenced by bioclimatic and environmental factors that determine the survival of its vectors—culicid mosquitoes. To analyse the risk of infection of vector-borne parasitic diseases as a control measure, ecological niche models, which take into account the behaviour of parasites in vectors, are good tools for this purpose, and colour maps can be made to report the areas at risk of infection with a precision of 1 km². We used ArcMap 10.8 to process both bioclimatic variables (related to temperature and precipitation) and environmental variables (such as water bodies, human footprint, and herbaceous and shrub density). After identifying the key predictor variables, we developed ecological niche models for Culex pipiens and Aedes albopictus using the MaxEnt algorithm, automated via the Kuenm R package. Additionally, we calculated the number of Dirofilaria spp. generations both annually and on a monthly basis as a function of temperature, using a custom R script. In most parts of the continent, the risk of infection is minimal during the winter months, except in some Mediterranean coastal regions, where some residual risk persists. In contrast, spring and summer bring an increased risk of infection in a significant part of the European continent, with the exception of the higher latitude areas together with the United Kingdom, the Scandinavian Peninsula (Norway, Sweden and Finland) and Russia, as well as high mountainous areas. Southern Europe, characterised by its warmer climate, experiences a high risk of infection, while in central Europe the risk becomes moderate to high. More risk assessments using the same methodology have also been carried out in Spain, and Portugal, Greece, Italy and Serbia with very interesting results. The forecasts do not bode well and a significant expansion of the risk of infection towards the north-eastern regions of the continent is foreseen. The creation of this type of maps where the risk of infection is analysed is a good control tool that should be taken into account by veterinary and public health staff, from their One Health point of view.

Project funded by CEVA Santé Animale.

References

Rodríguez-Escolar I, Hernández-Lambraño RE, Sánchez-Agudo JÁ, Collado-Cuadrado M, Savić S, Žekić Stosic M, Marcic D, Morchón R. Prediction and validation of potential transmission risk of Dirofilaria infection in Serbia and its projection to 2080. Front Vet Sci. 2024 Apr 3;11:1352236.
Rodríguez-Escolar I, Hernández-Lambraño RE, Sánchez-Agudo JÁ, Collado-Cuadrado M, Sioutas G, Papadopoulos E, Morchón R. Ecological niche modeling analysis (Cx. pipiens), potential risk and projection of Dirofilaria infection in Greece. Vet Parasitol. 2024 Jun;328:110172.
Rodríguez-Escolar I, Hernández-Lambraño RE, Sánchez-Agudo JÁ, Collado M, Pérez-Pérez P, Morchón R. Current Risk of Dirofilariosis Transmission in the Iberian Peninsula (Spain and Portugal) and the Balearic Islands (Spain) and Its Future Projection under Climate Change Scenarios. Animals (Basel). 2023 May 26;13(11):1764.
Genchi M, Escolar IR, García RM, et al. Dirofilaria immitisin Italian Cats and the Risk of Exposure by Aedes albopictus. Vector Borne Zoonotic Dis. 2024;24(3):151-158.

Anastasia Diakou
Full Professor, Laboratory of Parasitology and Parasitic Diseases, School of Veterinary Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki, Greece

CYRPUS: A HEARTWORM FREE COUNTRY UNDER THE THREAT OF INFECTION INVASION

Panagiotis Kokkinos1, Charalampos Attipa2, Anastasia Diakou3

1 Northwest Veterinary Specialists, Cheshire, UK
2 The Royal (Dick) School of Veterinary Studies and The Roslin Institute
University of Edinburgh, UK
3 School of Veterinary Medicine, Aristotle University of Thessaloniki, Greece

Keywords: Dirofilaria immitis, Cyprus, imported cases, epizootiology

Cyprus, an island in the eastern Mediterranean Sea, remains heartworm-free, as shown in a recent epizootiological study investigating the prevalence of Dirofilaria spp. infections in dogs1.

Since then, at least four cases of canine heartworm infection have been recorded. These dogs tested seropositive, although none exhibited clinical signs consistent with heartworm disease. In addition to serology, one dog tested positive on both Knott's and PCR tests, while two tested positive on PCR alone. One seropositive dog was PCR-negative. Two of the dogs had a confirmed history of travel to a hyperenzootic area in Greece, while the travel history of the other two remains unknown. The three PCR-confirmed cases received a “slow kill” heartworm treatment. Only one was retested nine months later with an in clinic antigen test and was found negative.

Cyprus' abundant native and invasive mosquito populations, which include confirmed heartworm vectors, coupled with favourable climate conditions, create an environment conducive to heartworm transmission. The introduction of a critical number microfilaraemic dogs can easily change Cyprus' status to enzootic. More concerning is the potential introduction of macrocyclic lactone-resistant D. immitis strains, which would pose a significant threat2. If such strains became established in a heartworm free area, they would be the dominant population, compromising the primary preventive measure against heartworm, i.e. macrocyclic lactone administration.

Given the potential risk of heartworm establishment in Cyprus, it is crucial for veterinarians and pet owners to remain vigilant. Screening (serology and Knott's test) for hearworm infection in dogs arriving to Cyprus from an enzootic area and the implementation of prophylactic treatment in case of travel to enzootic areas are essential. Veterinary professionals play a key role in educating pet owners about the risks associated with heartworm disease and the importance of preventive strategies, particularly in light of the emerging threat of macrocyclic lactone-resistant strains.

References

1. Kokkinos P, Dimzas D, Pantchev N, Tamvakis A, Balzer J, Diakou A. Filarial infections in dogs in Cyprus, an apparently heartworm free island. Vet Parasitol RSR. 2019 Dec;18:100330.
2. Traversa D, Diakou A, Colombo M, et al. First case of macrocyclic lactone-resistant Dirofilaria immitis in Europe - Cause for concern. Int J Parasitol Drugs Drug Resist. 2024 Aug;25:100549.

Christos Koutinas
Professor of companion animal medicine and cardiology, Companion Animal Clinic, Faculty of Veterinary Medicine, Aristotle University of Thessaloniki, Greece

The “slow kill” protocol in clinical practice: experience from its selective application.

Koutinas, C.K.¹DVM, PhD, Associate Professor in Companion Animal Medicine (Cardiology), Veterinary Faculty, School of Health Sciences, Aristotle University of Thessaloniki, Greece

Heartwom disease is one of the most common parasitic diseases in the dog, caused by the parasite Dirofilaria immitis. Due to the global presence of its intermediate host, mosquitos belonging mainly to the Culex and Aedes species, it also has a worldwide distribution and is endemic in many temperate and equatorial countries. D. immitis is a parasite of the cardiovascular system, reaching maturity in the pulmonary arteries and causing vascular and lung lesions that lead to pulmonary hypertension, right heart failure and occasionally death, especially when the worms transport back into the right ventricle and atrium. Treatment with arsenic compounds, mainly melarsomine, has been the mainstay of adulticide treatment for many years. Melarsomine, at the dose of 2.5 mg/kg, has a relatively rapid onset of action, reaching therapeutic levels within a few days after deep intramuscular injection. Both the American Heartworm Society (AHS) and the European Society of Dirofilariosis and Angiostrongylosis (ESDA) recommend three doses of melarsomine, within a period of one month, in order to achieve complete cure. Prior to the injection, the guidelines suggest a preparatory period of 60 days, during which doxycycline is prescribed at the dose of 5-10 mg/kg, every 12 hours, for 30 days, to eliminate Wolbachia pipientis, a bacterial symbiont of the parasite. This results in reducing the initial worm burden and minimizing the severe inflammatory reaction of the host after the death of the parasites. At the same time, both Societies advocate the use of macrocyclic lactones (e.g. moxidectin, milbemycin), at the beginning of the 60-day preparatory period, and monthly after that, to further reduce adult worm numbers and eliminate mosquito-infecting microfilariae from the circulation. It has been documented that ivermectin and moxidectin also have adulticidal properties (Kramer et al 2018) and, at the same time, clearance of microfilariaemia reduces the specific lung pathology caused by microfilariae. After the initial melarsomine injection, the most common and lethal complication is pulmonary thromboembolism caused by the dead and disintegrating adults. This risk can be significantly reduced by concurrently administering glucocorticoids at anti-inflammatory doses and enforcing cage-rest of the dog. The entire treatment regiment can take up to 4 months in total, after which all adult D. immitis worms in the canine host are largely eliminated. In general, the clinical condition markedly or gradually improves after treatment and pulmonary vascular and parenchymal lesions that accompany heartworm infection are gradually resolved. It should be noted that in advanced stages of the disease (stage III and IV, i.e. right heart failure and vena cava syndrome), the 60-day preparatory period could and probably should be significantly shortened, while accomodating heart failure treatment and surgical removal of the worms.

During the past few years, it has been suggested that a month of doxycycline, along with monthly moxidectin administration, can result in the eventual death of D. immitis adults and clinical as well as parasitological cure, even at late stages of the disease (Kramer et al 2018, Genchi et al 2019, Patterson et al 2020). As a result of limited availability of melarsomine in certain countries, along with its high cost (70 – 100 euros per 50 mg injectable bottle in Greece), this “slow-kill” protocol has gained popularity and has been a secondary low-cost alternative to the treatment plan with melarsomine that is traditionally suggested by both AHS and ESDA. Experimental studies have assessed the efficacy and safety of this protocol, with good results in parasite cure rates (Savadelis et al 2017) and there have been a few clinical studies evaluating the long-term effects of continuing worm presence in the pulmonary vasculature (Kramer et al 2018, Genchi et al 2019). However, the so called “moxi-doxy” approach is not currently endorsed by either Society as alternative treatment to melarsomine injections. Moreover, it has not been proven definitively that all worms are eventually eliminated in due time, and there have been reports of parasite survival for up to 3 years (Alberigi et al 2020, Ames et al 2020).

The clinical experience in Greece and our currently running retrospective analysis of 138 dogs that received only the combination of moxidectin, as a topical solution, and doxycycline (several different formulations), suggests that this type of treatment is primarily relatively safe in the long-term. There have been very few cases (<5%) of appearance or progression of symptoms in the dogs receiving moxidectine and doxycycline, even if the majority of dogs for which we have repeat serology did not become negative for D. immitis antigen within one year of starting treatment. At the same time, the monthly administration of moxidectin reduces the possibility of mosquito infection by microfilariae, which is a significant parameter in a long-term treatment plan that involves the continuing presence of the adult worms in the final host.

It should be noted that all of our cases were selected based on two main criteria; primarily, dogs receiving the combination of moxidectin and doxycycline were free of advanced symptoms (e.g. systemic signs, right heart failure or vena cava syndrome) or evidence of moderate to severe pulmonary hypertension in echocardiography, which was necessarily performed in all dogs prior to starting treatment; and secondarily, a heavy worm burden, as subjectively assessed based on presence of worms in the right pulmonary artery and its occlusion by the parasites, necessitated the use of melarsomine and precluded a “slow-kill” approach, regardless of other changes. In addition, this treatment’s follow-up period included echocardiographic re-examination, 3 – 4 months after administration of doxycycline, as well as continued administration of monthly moxidectin until serology for D. immitis became negative. Even if eventually some dogs did not undergo a second echocardiographic evaluation, in those that did there was very little evidence of disease progression. At this point, it should be stressed that a large number (>70%) of the animals that received this protocol were shelter dogs, some of which were eventually relocated or adopted and the carers were unable to bring them in for a second echocardiographic examination. As a result, there is also limited information regarding the serological antigen status of these dogs after the proposed treatment. However, in recent direct communication with the shelter carers or the owners themselves (75-80% of cases), the dogs were either clinically healthy and alive or had died of extracardiac causes not directly attributed to heartworm disease.

Since severely affected dogs will require further treatment for heart failure or mechanical removal, with the addition of sildenafil as a prerequisite, forgoing melarsomine administration for financial reasons becomes a moot point. In our experience, prolonged therapy with sildenafil, which is required in most cases with moderate to severe pulmonary hypertension, significantly reduces the advantage of a low-cost but long-term parasiticidal treatment. This is the main reason why we don’t advocate the use of a delayed adulticidal protocol in stage III and IV dogs. At the same time, our experience with shelters suggests that carers are much more likely to concentrate their financial efforts on severely affected or high-worm-burden dogs requiring melarsomine, resulting in a much more nuanced approach, with the caveat that echocardiography, using a budget-friendly and focused approach, should always precede any treatment decision. A robust follow-up protocol is additionally required to evaluate the long-term parasitic and clinical profile of these dogs.

Parallel to the concern of progression of pulmonary vasculature and parenchymal lesions, as well as systemic involvement (e.g. glomerulonephritis), a significant deterrent for “slow-kill” treatment remains the possibility of creating resistant strains of D. immitis by exposing the living adult worms to repeated doses of macrocyclic lactones. This may itself endanger the efficacy of prophylaxis in endemic countries. Until the effects of a sustained exposure to macrocyclic lactones and long-term effects of allowing worm presence inside the pulmonary arteries are better understood, the education of practitioners on the dangers of each treatment plan, along with favoring a nuanced, per-case approach to adulticidal therapy, remains the best option.

References:

Alberigi B, Fernandes JI, Paiva JP, Mendes-de-Almeida F, Knackfuss F, Merlo A, Labarthe N. Efficacy of semi-annual therapy of an extended-release injectable moxidectin suspension and oral doxycycline in Dirofilaria immitis naturally infected dogs. Parasit Vectors. 2020 Oct 6;13(1):503. doi: 10.1186/s13071-020-04380-z. PMID: 33023664; PMCID: PMC7539499.

Ames MK, VanVranken P, Evans C, Atkins CE. Non-Arsenical heartworm adulticidal therapy using topical moxidectin-imidacloprid and doxycycline: A prospective case series. Vet Parasitol. 2020 Jun;282:109099. doi: 10.1016/j.vetpar.2020.109099. Epub 2020 May 11. PMID: 32450463.

Genchi M, Vismarra A, Lucchetti C, Viglietti A, Crosara S, Gnudi G, Quintavalla C, Schaper R, Kramer L. Efficacy of imidacloprid 10%/moxidectin 2.5% spot on (Advocate®, Advantage Multi®) and doxycycline for the treatment of natural Dirofilaria immitis infections in dogs. Vet Parasitol. 2019 Sep;273:11-16. doi: 10.1016/j.vetpar.2019.07.011. Epub 2019 Jul 27. PMID: 31442887.

Kramer L, Crosara S, Gnudi G, Genchi M, Mangia C, Viglietti A, Quintavalla C. Wolbachia, doxycycline and macrocyclic lactones: New prospects in the treatment of canine heartworm disease. Vet Parasitol. 2018 Apr 30;254:95-97. doi: 10.1016/j.vetpar.2018.03.005. Epub 2018 Mar 9. PMID: 29657018.

Paterson T, Fernandez C, Burnett PJ, Lessey L, Hockley T, Hagen R, Coomansingh C, Sharma B, Chandrashekar R, Schaper R. Heartworm control in Grenada, West Indies: Results of a field study using imidacloprid 10% + moxidectin 2.5% and doxycycline for naturally-acquired Dirofilaria immitis infections. Vet Parasitol. 2020 Aug;284:109194. doi: 10.1016/j.vetpar.2020.109194. Epub 2020 Aug 15. PMID: 32866837.

Savadelis MD, Ohmes CM, Hostetler JA, Settje TL, Zolynas R, Dzimianski MT, Moorhead AR. Assessment of parasitological findings in heartworm-infected beagles treated with Advantage Multi® for dogs (10% imidacloprid + 2.5% moxidectin) and doxycycline. Parasit Vectors. 2017 May 19;10(1):245. doi: 10.1186/s13071-017-2190-9. PMID: 28526088; PMCID: PMC5437498.

Laura Kramer

Leca Florin
DMV, PhD, Laboratory of Veterinary Interventional Cardiology, "Doctor's Vet Univers" Clinic, Romania

Passionate about veterinary cardiology he has dedicated the last 20 years to its study and practice.

He founded in 2009 the first private veterinary clinic in Romania (Doctor's Vet Univers, Bucharest) exclusively dedicated to research, diagnosis and treatment of cardiovascular diseases in pets.

He founded in 2016 the Romanian Magazine of Veterinary Cardiology and co-opted in this project international and national experts of the highest professional level of veterinary cardiology (Stephen J. Ettinger, Clarke Atkins, Luca Ferasin, Roberto Santilli, Claudio Bussadori, Michele Borgarelli, Jens Haggstrom, Luigi Venco, Mark Oyama, Nuala Summmerfield, Jonathan Elliot, etc.) with the aim of promoting veterinary cardiology among general practitioners in Romania, but also to present internationally the results of Romanian colleagues. He is also Editor of the Romanian Journal of Veterinary Medicine and Pharmacology.

The year 2021 marked this achievement with the Romanian Magazine of Veterinary Cardiology International Conference, where the special guest was Prof. Stephen J. Ettinger, the living legend of international veterinary medicine.

Since 2011 he has given more than 100 scientific presentations and workshops at relevant National and International Conferences and Congresses.

His scientific research on the cardiovascular system has resulted in numerous scientific articles and the completion of a PhD thesis in the field of Physiology.

In 2021 he established the first Veterinary Interventional Cardiology Laboratory in Romania, within the "Doctor's Vet Univers" clinic.

He founded the "AvantGard CardioTeam" (international multidisciplinary team of Interventional Cardiology) and has achieved numerous firsts in cardiovascular surgery and veterinary interventional cardiology in Romania (Percutaneous Balloon Valvuloplasty in Pulmonary Stenosis, Endovascular Pacing with active and passive fixation, Percutaneous Occlusion of Persistent Ductus Arteriosus using AVP and Nit-Occluder in dogs, Percutaneous Pericardial Balloon Balloon "High Pressure", Implantable ILR Holter, Aorto-iliac thrombectomies in felines; Arterial and venous catheterization in dogs, Endocardial puncture in dogs, Caval Syndrome Surgery, etc.).

He has performed more than 50 surgeries in Caval Syndrome in dogs, accumulating a vast experience in this type of procedure, internationally recognized and appreciated expertise, which has been concretized through collaborations with two of the most prestigious universities in Europe (L'Ecole vétérinaire d'Alfort, Paris, France and University of Veterinary Medicine, Vienna, Austria).

Leca Florin
DMV, PhD, Laboratory of Veterinary Interventional Cardiology, "Doctor's Vet Univers" Clinic, Romania

View Abstract

EVPC Invited Speakers

Emily Jenkins
Professor and Graduate Chair of the Department of Veterinary Microbiology, Head of the Zoonotic Parasite Research Unit, Western College of Veterinary Medicine at the University of Saskatchewan, Saskatoon, Canada

Zoe Polizopoulou
DVM, PhD, DipECVCP Diagnostic Laboratory School of Veterinary Medicine Aristotle University of Thessaloniki, Greece

Vasilios Tsiouris
DVM, MSc., PhD
EBVS® European Specialist in Poultry Veterinary Science, Assoc. Professor in Avian Medicine School of Veterinary Medicine, Aristotle University of Thessaloniki Greece

Rania Farmaki
DVM,PhD, DipECVD
EBVS® European Specialist in Veterinary Dermatology Assistant Professor, School of Veterinary Medicine, Faculty of Health Sciences, Aristotle University of Thessaloniki, Greece

Mite-related skin diseases in dogs

R. Farmaki
Faculty of Health Sciences, Aristotle University of Thessaloniki, Greece

Mites such as Sarcoptes scabiei, Otodectes cynotis, Cheylletiella spp, Demodex canis, Neotrombicula autumnalis, and Straelensia cynotis are responsible for several skin diseases, some of which have zoonotic potential. Sarcoptic mange is an extremely pruritic, highly contagious disease, characterized by papulocrustous lesions that commonly affect face and ventral areas, specifically the ear pinnae, elbows, and hocks. Additional lesions are seen as a result of self-trauma and chronicity of skin inflammation. Scabies incognito is a term used to describe cases with minimal lesions that are difficult to diagnose. Norwegian or crusted scabies is a rare skin disease characterized by diffuse crusted, non-pruritic dermatitis with high numbers of mites in skin scrapings that is associated with immunosuppression due to systemic disease or malnutrition. Multiple skin scrapings may be required to reveal the presence of the parasite, and ideal sites for skin examination are new lesional areas and marginal areas of the pinnae, especially where pruritus is noted during scraping. Serological tests are also available for Sarcoptes scabiei. Otodectic mange is a common cause of otitis in dogs, accompanied by excessive dark brown ear wax, the characteristic appearance of “coffee grounds”, and itching. Mites may be seen less commonly seen outside of the ear canal on the body. Cheylletiellosis, also known as walking dandruff, is characterized by scaling of the skin, and pruritus is variable. It can be easily diagnosed by examining skin and hair shafts. Demodicosis may be juvenile or adult onset, localized, with limited or multiple affected areas, or generalized with variable pruritus. Skin lesions are mainly characterized by alopecia-hypotrichosis, erythema, crusting and comedones. Juvenile onset demodicosis is the result of an inherited defect in the immune system and may be self-limiting. On the other hand, adult-onset demodicosis is associated with underlying diseases and immunosuppression. Trombiculosis is a seasonal dermatitis, with variable pruritus caused by the larval stage that is seen clustering on protected body areas and skin folds on the head, pinnae, feet and tail. Straelensia cynotis is a papular to nodular dermatitis usually non-pruritic that affects the dorsal body and mild to moderate forms are asymptomatic in contrast to a more severe infestation that can be painful.

Conflict of interest: None declared

Dr. Mark Bowen
EBVS® European Specialist in Veterinary Sports Medicine and Rehabilitation, Director of Education EBVS

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