Comparative speed of kill of sarolaner (Simparica®) and afoxolaner (NexGard®) against induced infestations of Ixodes holocyclus on dogs

Immunomic Investigation of Holocyclotoxins to Produce the First Protective Anti-Venom Vaccine Against the Australian Paralysis Tick, Ixodes holocyclus

Venom producing animals are ubiquitously disseminated among vertebrates and invertebrates such as fish, snakes, scorpions, spiders, and ticks. Of the ~890 tick species worldwide, 27 have been confirmed to cause paralysis in mammalian hosts. The Australian paralysis tick (Ixodes holocyclus) is the most potent paralyzing tick species known. It is an indigenous three host tick species that secretes potent neurotoxins known as holocyclotoxins (HTs). Holocyclotoxins cause a severe and harmful toxicosis leading to a rapid flaccid paralysis which can result in death of susceptible hosts such as dogs. Antivenins are generally polyclonal antibody treatments developed in sheep, horses or camels to administer following bites from venomous creatures. Currently, the methods to prevent or treat tick paralysis relies upon chemical acaricide preventative treatments or prompt removal of all ticks attached to the host followed by the administration of a commercial tick-antiserum (TAS) respectively. However, these methods have several drawbacks such as poor efficacies, non-standardized dosages, adverse effects and are expensive to administer. Recently the I. holocyclus tick transcriptome from salivary glands and viscera reported a large family of 19 holocyclotoxins at 38-99% peptide sequence identities. A pilot trial demonstrated that correct folding of holocyclotoxins is needed to induce protection from paralysis. The immunogenicity of the holocyclotoxins were measured using commercial tick antiserum selecting HT2, HT4, HT8 and HT11 for inclusion into the novel cocktail vaccine. A further 4 HTs (HT1, HT12, HT14 and HT17) were added to the cocktail vaccine to ensure that the sequence variation among the HT protein family was encompassed in the formulation. A second trial comparing the cocktail of 8 HTs to a placebo group demonstrated complete protection from tick challenge. Here we report the first successful anti-venom vaccine protecting dogs from tick paralysis.

Approaches to Integrated Parasite Management (IPM) for Theileria orientalis with an Emphasis on Immunity

Integrated parasite management (IPM) for pests, pathogens and parasites involves reducing or breaking transmission to reduce the impact of infection or infestation. For Theileria orientalis, the critical impact of infection is the first wave of parasitaemia from the virulent genotypes, Ikeda and Chitose, associated with the sequelae from the development of anaemia. Therefore, current control measures for T. orientalis advocate excluding the movement of naïve stock from non-endemic regions into infected areas and controlling the tick Haemaphysalislongicornis, the final host. In Australia, treatment of established infection is limited to supportive therapy. To update and expand these options, this review examines progress towards prevention and therapy for T. orientalis, which are key elements for inclusion in IPM measures to control this parasite.

Current review of isoxazoline ectoparasiticides used in veterinary medicine

The isoxazolines are a novel class of ectoparasiticides with potent inhibitory activity on glutamate- and gamma-aminobutyric acid-gated chloride channel located in nervous system of invertebrates. In recent years, studies have been performed to evaluate the efficacy and safety of isoxazolines against various types of ectoparasites, including fleas, ticks, and mites. As more single and combined isoxazoline products have been approved by the United States Food and Drug Administration and European Medicines Agency, a more comprehensive understanding of isoxazolines becomes essential for veterinary clinical practitioners. This article provides a complete review of isoxazolines with respect to pharmacodynamics, pharmacokinetics, ectoparasiticidal efficacy, and safety, which will provide veterinarians information to allow them to make the best choice of ectoparasiticide for their clients' specific needs.

Protecting dogs and cats against the Australian paralysis tick, Ixodes holocyclus (Acari: Ixodidae): A review of the Australian acaricide registration process

Tick control is mainly achieved through the use of effective ectoparasiticides that can be either dermally or systemically distributed in/on the host. Before any acaricide can be legally made available to veterinarians and pet owners, it must demonstrate efficacy in a series of well-designed dose confirmation studies. The data generated during these studies are then reviewed by government regulators and used for the registration of the acaricide. In Australia, the most significant tick species is the Australian paralysis tick, Ixodes holocyclus. This three-host tick produces a potent neurotoxin (holocyclotoxin) that induces a rapidly ascending flaccid paralysis that can be fatal to companion animals and larger mammals such as cattle and horses. The Australian Pesticides and Veterinary Medicines Authority (APVMA) is the national Australian regulator which sets the data requirements for the registration of acaricides. This paper reviews the requirements set by the APVMA and puts them in direct context with the biology, distribution and reported acaricide susceptibility of I. holocyclus. An overview of acaricides currently registered in Australia for the control of I. holocyclus in dogs and cats, their reported efficacy data and the conduct of I. holocyclus efficacy trials are also provided.

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A review of the requirements for the conduct of acaricide efficacy trials for Ixodes holocyclus was undertaken.

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The requirements of the Australian government regulator were put in direct context with the biology of the species.

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The need for the inclusion of Far North Queensland ticks into tick studies needs to be further assessed.

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At present, there is no evidence of acaricide resistance in Ixodes holocyclus.

Recent Advancements in the Control of Cat Fleas

Simple Summary

The cat flea Ctenocephalides felis felis is the most important pest of domesticated cats and dogs worldwide. This review covers the recent advancements in the control of cat fleas. Over the years, there has been an interest in using ecologically friendly approaches to control fleas. To date, no biological, natural, or cultural means have been discovered that mitigate flea infestations. The recent registration of novel topical and oral therapies promises a new revolution in the control of fleas and ticks and the diseases associated with them.

Abstract

With the advent of imidacloprid and fipronil spot-on treatments and the oral ingestion of lufenuron, the strategies and methods to control cat fleas dramatically changed during the last 25 years. New innovations and new chemistries have highlighted this progress. Control strategies are no longer based on the tripartite approach of treating the pet, the indoor environment, and outdoors. The ability of modern therapies to break the cat flea life cycle and prevent reproduction has allowed for the stand-alone treatments that are applied or given to the pet. In doing so, we have not only controlled the cat flea, but we have prevented or reduced the impact of many of the diseases associated with ectoparasites and endoparasites of cats and dogs. This review provides an update of newer and non-conventional approaches to control cat fleas.

Efficacy of combination products containing sarolaner, moxidectin and pyrantel (Simparica Trio™) or afoxolaner and milbemycin (NexGard Spectra®) against induced infestations of Ixodes holocyclus in dogs

BACKGROUND

The Australian paralysis tick, Ixodes holocyclus, causes tick paralysis in dogs and cats in the eastern coastal regions of Australia. Prevention is the best option to protect dogs against this potentially fatal disease and sarolaner provides rapid and sustained efficacy against I. holocyclus. In this laboratory study, the efficacy of two combination endectocides containing sarolaner + moxidectin + pyrantel (Simparica Trio™) and afoxolaner + milbemycin (NexGard Spectra^®) was evaluated against an artificial infestation of I. holocyclus.

METHODS

Twenty-four (n =24) foxhounds were randomly allocated to three treatment groups and artificially infested with 30 adult female viable ticks on Days - 1, 7, 14, 21, 28 and 35. On Day 0, dogs in each treatment group were treated with either Drontal^® (control group), Simparica Trio™ at the label dose to provide minimum doses of sarolaner (1.2 mg/kg), moxidectin (24 µg/kg) and pyrantel (5 mg/kg) or NexGard Spectra^® to provide minimum doses of afoxolaner (2.5 mg/kg) and milbemycin (0.5 mg/kg). Live tick counts were performed at 48 and 72 hours after treatment and after each re-infestation on Days 7, 14, 21, 28 and 35. Efficacy was determined at each time point relative to counts for control dogs based on geometric means.

RESULTS

Against an existing infestation, efficacy of both Simparica Trio™ and NexGard Spectra^® was 99.6% and 100% at 48 and 72 h time points, respectively (P = 1.000). Against subsequent weekly infestations, treatment with Simparica Trio™ and NexGard Spectra^® resulted in efficacy of ≥ 97.7% and ≥ 95.5% (P ≥ 0.0911), respectively at the 48 h time point and at the 72 h time point, Simparica Trio™ and NexGard Spectra^® resulted in efficacy of ≥ 99.0% and ≥ 98.4% (P ≥ 0.0511), respectively. There were no treatment-related adverse events in the study.

CONCLUSIONS

Single doses of Simparica Trio™ and NexGard Spectra^® were highly efficacious and provided comparable efficacy against the Australian paralysis tick, I. holocyclus for up to 35 days.

Safety and efficacy of a new spot-on formulation of selamectin plus sarolaner in the treatment and control of naturally occurring flea infestations in cats presented as veterinary patients in Australia

Background

The safety and efficacy of a new spot-on formulation of selamectin plus sarolaner were evaluated for the treatment and control of natural flea infestations on cats in two non-randomised, multi-centre clinical trials conducted in 8 different locations in Queensland, Australia.

Methods

One hundred and four cats from 65 different households were enrolled across the two studies. Demographic characteristics of cats in the two studies were similar. The new spot-on formulation of selamectin and sarolaner was administered topically once a month for 3 consecutive months at a minimum dosage of 6 mg/kg selamectin (dose range 6–12 mg/kg) plus 1 mg/kg sarolaner (dose range 1–2 mg/kg). Cats were dosed on Days 0 (pre-treatment), 30 and 60 and physical examinations and flea counts were conducted on Days 0, 30, 60 and 90. Efficacy assessments were based on the percentage reduction in live flea counts post-treatment compared to Day 0.

Results

In Study A, at enrolment, primary cats had flea counts ranging from 6 to 107 (arithmetic mean 21.0). The selamectin and sarolaner spot-on formulation resulted in arithmetic mean efficacy of 98.0%, 100% and 100% on Days 30, 60 and 90, respectively. In Study B, at enrolment, primary cats had flea counts ranging from 6 to 22 (arithmetic mean 10.0). The selamectin and sarolaner spot-on formulation resulted in arithmetic mean efficacy of 99.7%, 100% and 100% on Days 30, 60 and 90, respectively.

Conclusions

The new spot-on formulation of selamectin plus sarolaner topically administered at monthly intervals at the minimum dosage of 6.0 mg/kg selamectin and 1.0 mg/kg sarolaner was safe and highly effective against natural infestations of fleas under a range of geographical conditions, representative of both tropical and subtropical regions of Australia.

Efficacy of sarolaner (Simparica®) against induced infestations of Haemaphysalis longicornis on dogs

BACKGROUND

Haemaphysalis longicornis is the major tick affecting dogs in most of the East Asia/Pacific region and has recently been detected in a number of areas of the USA. This tick is a vector for a number of pathogens of dogs, other mammals and humans. In this study, the efficacy of a single oral administration of sarolaner (Simparica^®, Zoetis) at the minimum label dosage (2 mg/kg) was evaluated against an existing infestation of H. longicornis and subsequent weekly reinfestations for 5 weeks after treatment.

METHODS

Sixteen dogs were ranked on pretreatment tick counts and randomly allocated to treatment on Day 0 with sarolaner at 2 mg/kg or a placebo. The dogs were infested with H. longicornis nymphs on Days - 2, 5, 12, 19, 26 and 33. Efficacy was determined at 48 hours after treatment and subsequent re-infestations based on live tick counts relative to placebo-treated dogs.

RESULTS

There were no adverse reactions to treatment. A single dose of sarolaner provided 100% efficacy on Days 2, 7, 14 and 21; and ≥ 97.4% efficacy on Days 28 and 35. Considering only attached, live ticks, efficacy was 100% for the entire 35 days of the study. Geometric mean live tick counts for sarolaner were significantly lower than those for placebo on all days (11.62 ≤ t_(df) ≤ 59.99, where 13.0 ≤ df ≤ 14.1, P < 0.0001).

CONCLUSIONS

In this study, a single oral administration of sarolaner at 2 mg/kg provided 100% efficacy against an existing infestation of H. longicornis nymphs and ≥ 97.4% efficacy (100% against attached ticks) against weekly reinfestation for at least 35 days after treatment.

Laboratory evaluations of the 3-month efficacy of oral lotilaner (Credelio™) against experimental infestations of dogs with the Australian paralysis tick, Ixodes holocyclus

BACKGROUND

From three days following host attachment, the Australian paralysis tick, Ixodes holocyclus, secretes a neurotoxin that annually causes paralysis in approximately 10,000 domestic pets. Lotilaner, a novel isoxazoline formulated in a chewable flavoured tablet (CredelioTM), produces rapid onset of acaricidal activity in dogs, with an efficacy duration of at least one month. Two studies were performed to determine the efficacy of lotilaner against I. holocyclus infestations over 3 months.

METHODS

Both studies included 16 dogs, ranked according to I. holocyclus counts on Day -5 (from infestations on Day -8) and blocked into pairs. One dog in each pair was randomized to be a sham-treated control, the other to receive lotilaner at a minimum dose rate of 20 mg/kg on Day 0. Dogs were dosed in a fed state. Infestations were performed in both studies on Days -8 (to determine the tick carrying capacity of each dog) -1, 28, 56, 70, 77 and 84, and additionally in Study 1 on Day 91, in Study 2 on Days 14 and 42. In Study 1, ticks were counted and assessed as alive or dead at 24, 48 and 72 h post-initial infestation and post-subsequent re-infestations. In study 2, ticks were counted at 24, 48 and 72 h post-dosing or post-re-infestation. Efficacy was determined by the percent reduction in live attached tick counts in the lotilaner group compared to control.

RESULTS

Within 48 h post-treatment in Study 1 and within 72 h post-treatment in Study 2 all lotilaner-group dogs were free of live ticks. By 72 h post-infestation, efficacy in Study 1 remained at 100% through Day 87, except on Day 31 when a single tick was found on one dog, and through Day 59 in Study 2. Efficacy exceeded 95% through the final assessment in each study (Days 94 and 87 in Studies 1 and 2, respectively).

CONCLUSION

These results demonstrate that lotilaner quickly kills existing I. holocyclus infestations. By providing 95.3-100.0% protection through at least 87 days post-treatment, lotilaner can be a valuable tool in reducing the risk of tick paralysis in dogs.

Diagnosis and Treatment of Lower Motor Neuron Disease in Australian Dogs and Cats

Diseases presenting with lower motor neuron (LMN) signs are frequently seen in small animal veterinary practice in Australia. In addition to the most common causes of LMN disease seen world-wide, such as idiopathic polyradiculoneuritis and myasthenia gravis, there are several conditions presenting with LMN signs that are peculiar to the continent of Australia. These include snake envenomation by tiger (Notechis spp.), brown (Pseudonaja spp.), and black snakes (Pseudechis spp.), tick paralysis associated with Ixodes holocyclus and Ixodes coronatus, and tetrodotoxins from marine animals such as puffer fish (Tetraodontidae spp.) and blue-ring octopus (Hapalochlaena spp.). The wide range of differential diagnoses along with the number of etiological-specific treatments (e.g., antivenin, acetylcholinesterase inhibitors) and highly variable prognoses underscores the importance of a complete physical exam and comprehensive history to aid in rapid and accurate diagnosis of LMN disease in Australian dogs and cats. The purpose of this review is to discuss diagnosis and treatment of LMN diseases seen in dogs and cats in Australia.

Efficacy and safety of sarolaner (Simparica®) in the treatment and control of naturally occurring flea infestations in dogs presented as veterinary patients in Australia

BACKGROUND

The efficacy and safety of a novel isoxazoline compound, sarolaner (Simparica^®, Zoetis) and spinosad (Comfortis^®, Elanco) as a positive control were evaluated for the treatment and control of natural flea infestations on dogs in two randomised, blinded, multi-centric clinical trials conducted in 11 veterinary clinics in northeastern and southeastern states of Australia.

METHODS

A total of 162 client-owned dogs (80 in northern study and 82 in southern study) from 105 households were enrolled. Each household was randomly allocated to receive either sarolaner (Simparica^®, Zoetis) or spinosad (Comfortis^®, Elanco). Dogs were dosed on Days 0, 30 and 60 and physical examinations and flea counts were conducted on Days 0, 14, 30, 60 and 90. Efficacy assessments were based on the percentage reduction in live flea counts post-treatment compared to Day 0.

RESULTS

In the northern study, at enrolment, primary dogs had flea counts ranging from 5 to 772. At the first efficacy assessment on Day 14, sarolaner resulted in 99.3% mean reduction in live flea counts relative to Day 0, compared to 94.6% in the spinosad group. On Day 30, the sarolaner-treated group had mean efficacy of 99.2% compared to 95.7% in the spinosad-treated group, and on days 60 and 90, both groups had mean efficacies of ≥ 98.8%. In the southern study, at enrolment, primary dogs had flea counts ranging from 5 to 156. Both sarolaner and spinosad resulted in ≥ 96.7% mean reduction in live flea counts on Day 14. On Day 30, the sarolaner-treated group had mean efficacy of 99.5% compared to 89.7% in the spinosad-treated group, and on days 60 and 90, both groups had mean efficacies of ≥ 98.6%. No treatment-related adverse events were observed in either study.

CONCLUSIONS

A single monthly dose of sarolaner (Simparica^®) administered orally at 2-4 mg/kg for three consecutive months was well tolerated and provided excellent efficacy against natural infestations of fleas under a range of Australian field conditions including different climatic and housing conditions. Similar efficacy was observed with spinosad (Comfortis^®) after the second and third monthly treatments.