Effectiveness of the Combination of Imidacloprid/ Moxidectin/ Praziquantel and Moxidectin/ Praziquantel Applied Topically in Dogs with Endoparasites and Ectoparasites

1. INTRODUCTION

Dogs can harbor a large number of gastrointestinal parasites [1], many of these are zoonotic, and this is why they table are considered a public health problem worldwide [1-4]. In addition, dogs can also have ectoparasites of clinical and zoonotic importance [5]. Therefore, antiparasitic treatments appear to be significantly effective. Topically applied antiparasitic drugs used in dogs have evolved in terms of active ingredients, but progress has also been made through the development of drugs that control both ectoparasites and enteroparasites (nematodes and cestodes) [6]. Some studies have evaluated the chemical compatibility and the dermal and systemic safety of external application drugs that contain Moxidectin/ Imidacloprid as active ingredients having beneficial results [7]. Nowadays, combinations of new topical formulations, that could be useful to control ectoparasites and endoparasites in dogs, are available; nevertheless, there are few studies on the effectiveness of these presentations. This research aims to evaluate the effectiveness of Moxidectin 3.5g/ Praziquantel 10.0g and Imidacloprid 10.0g/ Moxidectin 3.5g/ Praziquantel 10.0g combinations applied topically in dogs with helminths (cestodes and nematodes) and ectoparasites, respectively.

2. MATERIALS AND METHODS

This study was conducted from May to October 2021 at the Parasitology Laboratory of the DERMAVET Veterinary Hospital, in Mexico City, Mexico.

3. RESULTS

4. DISCUSSION

A single product that can treat and prevent all the range of taxa of ectoparasites and enteroparasites that affect dogs is not available, consequently, the use of antiparasitic drugs combinations will remain the best therapeutic and preventive solution for many years [6], therefore, it is important to evaluate the effectiveness of new existing formulations in the market. In the study, there were dogs that tested positive for five genera of nematodes: Toxocara canis, Ancylostoma caninum, Uncinaria sp., Trichuris vulpis, and Strongyloides stercoralis agreeing with what Alvarado-Esquivel et al. [15] reported, who mention that the parasites stated before were also more prevalent in their study; however, they did not report Toxocara canis that we found and they reported Giardia canis, which was not found in this study. In addition to the dog’s health problems, the feces represent a significant zoonotic threat because humans who ingest larvae eggs of Toxocara sp. can develop visceral or ocular larva migrans [16]. The viable survival of larvae Ascaris eggs can remain for several years in the environment; for this reason, prevention and immediate elimination of patent infections are important measures to minimize the risk of zoonotic transmission [17]. Likewise, Ancylostoma spp. has a zoonotic potential [18], this is why the opportune treatment of the infection is essential to reduce the negative effects in the host, as well as minimize the risk of environmental contamination with worm eggs that can lead to the zoonotic transmission [17].

Some animals tested positive for two genera of cestodes: Dipylidium caninum and Taenia spp. The presence of Dipylidium caninum in the dogs of this study has been previously reported as a zoonosis in children [19]; therefore, it is a parasite that must be controlled to avoid public health problems. The species of Taenia in domestic dogs can cause cysticercosis and coenurosis in a wide range of intermediary hosts, including humans. Mostly, Taenia in dogs is distributed at a worldwide level, but some species transmitted by wildlife can be specific to certain regions. Overall, there is little information about the composition and frequency of the species in most regions around the world, making risk strategies and control evaluation difficult [19].

The study identified 11 species of ectoparasites, such as, the ectoparasite L. setosus, which is a sucking louse, spends its entire life in the host, and some species cannot survive more than a few days outside the host [20]. Therefore, lice transmission takes place by direct contact. Nevertheless, contaminated brushes, combs, and different materials also influence the contagion [21]. In addition to causing pediculosis in dogs, L. setosus is also important in terms of being a vector of Dipylidium caninum, an endoparasite found in this study. Rickettsia felis is an obligate intracellular Gram-negative bacterium that causes spotted fever transmitted by fleas to humans. In the last decades, R. felis has been detected worldwide in fleas of Ct. felis and Ct. canis [22], both ectoparasites observed in this study; therefore, their control is important for public health. Canine scabies (Sarcoptic scabiei) is an intensely itchy and transmissible skin disease of dogs caused by the mite Sarcoptes scabiei [23]. This ectoparasite was also found in this study. It is important to have good pharmacological management of this parasite since the clinical presentation is characterized by pruritus and severe scratching, alopecia, inflammation, excoriation, and hyperkeratosis, potentially associated with secondary bacterial infection and pyoderma. The disease is diagnosed at a worldwide level and can affect dogs of all breeds, age, and gender. The infestation is highly contagious in humans and can develop skin lesions after being in contact with an infested host [24]. In this study, a dog tested positive for Dermanyssus hirundinis (a bird mite), even though this parasite is found in birds like pigeons, some dogs with hunting habits can become infested with this louse. Molecular studies have demonstrated that the different species of Dermanyssus can adapt to different hosts [25]. We also found D. canis and D. injai mites, the control of these mites is important since they come from outer sources on the mammals' skin [26], which cause inflammatory disease of the skin when the population of these parasites surpasses the balance point. In this research, we also found ticks, in previous years it was not a common question to find this type of ectoparasites; nevertheless, they are now present and preventive management of these parasites should be carried out since in addition to causing health problems in patients they are also vectors of multiple diseases for humans [27]. This study demonstrated that the treatment with Imidacloprid 10.0g/ Moxidectin 3.5g/ Praziquantel 10.0g was also effective to decrease lesions associated with pruritus in dogs that were positive for ectoparasites. This result is important because the L. setosus are very active lice and a severe infestation can cause acute irritation and fragile skin with erythema, peeling, scabs, papules, and pruritus, similar to the way of mite S. scabiei. The pruritus and the associated scratching cause traumatic damage to the skin that includes alopecia and secondary bacterial infection (pyoderma) [28].

The treatment had significant effectiveness from day 7 AT against the five nematodes analyzed (average effectiveness of ≥77.25%) having greater effectiveness to treat Uncinaria sp. (89.48%) and Trichuris spp. (87.5%). The effectiveness of Moxidectin/ Praziquantel was ≥99.8% from day 14 to day 35 AT on all the nematodes analyzed. This result was better compared to one presented in a previous study that demonstrated the effectiveness of >95% of the combination of Emodepside plus® tablets of Praziquantel against Uncinaria sp. in dogs [29]. The use of this combination for the parasite Strongylus spp. had no side effects in these patients, as they would have with the use of Ivermectin or the anthelmintic resistance of Fenbendazole, commonly used treatments for this parasite [30].

The effectiveness and persistence of the treatment with Moxidectin 3.5g/ Praziquantel 10.0g on the intestinal cestodes in dogs showed a significant difference in the effectiveness against Dipylidium spp. and Taenia spp. (effectiveness of 82.7%) from day 7 AT. The effectiveness of Moxidectin/ Praziquantel had 100% effectiveness from day 14 AT in the case of Dipylidium caninum until day 35; in the case of Taenia spp. it reached 100% effectiveness by day 28 and day 35 AT. This would not be possible if the “transmitter reservoir” flea is not eliminated at the same time. This result is related to Praziquantel which has been described as an anthelmintic agent with activity against a broad spectrum of trematodes and cestodes [31]. This result agrees with what Charles et al. [32] reported, who said that the topical solution of Emodepside/ Praziquantel turned out to be safe and highly effective against infections by D. caninum and T. taeniformis in cats that are easily stressed and more sensitive to antiparasitic drugs. In several studies, Praziquantel has been safe and effective in oral and topical presentations [33]. The treatment with Imidacloprid 10.0g/ Moxidectin 3.5g/ Praziquantel 10.0g proved its effectiveness in all ectoparasites from day 7 AT, until reaching 100% effectiveness by day 14 AT in the L. setosus, Ct. Canis, A. americanum, Ixodes spp., R. sanguineus, and D. reticulatus species. The only specimen of D. hirundinis identified in a dog was eliminated by day 7 AT. The treatment reached 100% effectiveness by day 30 AT in all the species of ectoparasites found in dogs. These results are important since it was possible to have proper control of these ectoparasites with zoonotic potential, which agrees with what Krüdewagen [7], reported, where they tested the effectiveness and safety of the topical spot-on application of Imidacloprid/ Moxidectin in dogs with these ectoparasites. In addition, Petersen et al. [34] showed that Imidacloprid/ Moxidectin applied topically every month during the study of 84 days did not reach the proportion of mite-free dogs required to prove good effectiveness; however, the use of Imidacloprid 10.0g/ Moxidectin 3.5g/ Praziquantel 10.0g in this study has a high concentration of Moxidectin (3.5%), which presents the product as a good choice for this pathology since the results of this study show that it eliminates 100% mites and contributes to the elimination pathway of these ectoparasites. The effect of Imidacloprid 10.0g/ Moxidectin 3.5g/ Praziquantel 10.0g against ticks is associated with the high concentration of Moxidectin (3.5%), considering that other studies in which the concentration was of 2.5% did not have this effect. These results are also related to the function of Imidacloprid, which is a neonicotinoid insecticide that acts as a strong agonist of the nicotinic acetylcholine receptors in the postsynaptic membrane causing the sustained depolarization of the neuron and death of the flea, louse or tick [33, 34].

CONCLUSION

The application of Moxidectin 3.5g/ Praziquantel 10.0g applied topically was effective to treat nematodes (Toxocara canis, Ancylostoma caninum, Uncinaria sp., Strongyloides stercoralis, and Trichuris vulpis) and cestodes (Dipylidium caninum and Taenia sp.). A single topical treatment of Imidacloprid 10.0g/ Moxidectin 3.5g/ Praziquantel 10.0g was also safe and highly effective to treat ectoparasites like L. setosus, Ct. felis, S. scabiei, Ct. canis, A. americanum, D. hirundinis, D. canis, Ixodes spp., R. sanguineus, D. injai, and D. reticulatus in parasitized dogs. It was also a useful treatment to control pruritus and decrease lesions.

REFERENCES