VETcpd - Vol 4 - Issue 2 - Page 49

DOGS GO EVERYWHERE.SO DO TICKS AND FLEAS.

Bravecto® contains fl uralaner. Indicated for the treatment of tick and fl ea infestations in dogs. POM-V Further information is available from the SPC or from MSD Animal Health, Walton Manor, Milton Keynes MK7 7AJ.

Use medicines responsibly. For more information please refer to the Responsible Use sections of the NOAH website.

THE BIG TICK PROJECT SHOWED NEARLY 1 IN 3 DOGS EXAMINED HAD TICKS ON THEM.2

MSD Animal Health, creators of

Over 90% of pet owners questioned prefer Bravecto® to monthly fl ea and tick products.3

Prescribing Bravecto® enables less frequent dosing than monthly treatments, meaning less stress and less hassle for you, your owners and their dogs.

1. In dogs, Bravecto® provides a 12-week immediate and persistent tick-killing activity against Ixodes ricinus, Dermacentor reticulatus and D. variabilis and 8-week immediate and persistent killing activity against Rhipicephalus sanguineus

2. Abdullah S, Helps C, Tasker S, Newbury H, Wall R, 2016. Ticks infesting domestic dogs in the UK: a large-scale surveillance programme. Parasites & Vectors; 9:3913. MSD CORE Research Internal Study. Pet Owner Treatment Satisfaction and Medication Adherence to Bravecto® when prescribed to over 500 pet owners in the UK. Dec 2016

MSD0089 Vet CPD bravecto Ad 210x297.indd 1 28/04/2017 09:59

Recent developments in ectoparisiticides

Ian Wright BVMS BSc MSc MRCVS

Ian is a practising Veterinary Surgeon at the Withy Grove Veterinary Surgery and Co-owner of the Mount Veterinary Practice in Fleetwood. He has a Master’s degree in Veterinary Parasitology and is Head of the European Scientifi c Counsel of Companion Animal Parasites (ESCCAP UK & Ireland).

Ian is regularly published in peer reviewed journals and is a peer reviewer for the Veterinary Parasitology and Companion Animal journal. Ian continues to carry out parasite prevalence research in practice.

The Mount Veterinary Practice 1 Harris Street, Fleetwood, FY7 6QX

Tel: 01253 875547 or 07816337293

E-mail: hammondia@hotmail.com

VETcpd - Parasitology

The past decade has seen a proliferation of antiparasitic drugs and products reach the veterinary market. This has occurred in the face of increased parasitic disease risk as a mild climate and increased pet movement has led to a wider distribution of parasites and their vectors. New products have allowed fl exibility in terms of routes of product administration, duration of action and number of target species. This article will consider some of the new drugs and combination products available and the advantages that a growing parasiticide market can bring in response to the increasing challenges of parasite control in UK cats and dogs.

Key words: ectoparisiticide, endectocide, parasites, treatment, control

IntroductionThe veterinary ectoparisiticide market is rapidly expanding with a proliferation of antiparasitic drugs and products reaching

the veterinary market. This has led to claims that the market is saturated with a surplus of parasiticides. In reality, these products have fi lled a number of gaps in the market and created fl exibility in terms of means of administration and range of parasites that individual products treat. This increase in choice of product comes in the face of a rising parasite challenge in cats and dogs. Successive mild winters and wet summers have allowed fl eas to proliferate and ticks to quest and feed all year round. Babesia canis has established in Dermacentor spp ticks in Essex (Swainsbury et al. 2016) and Angisotrongylus vasorum lungworm is now present in endemic foci across the whole of the UK (Taylor et al. 2015). Parasiticides are a vital component of parasite control and this article will consider how new ectoparisticide products are helping to meet these challenges.

Flea productsA wide range of fl ea products are available which, when applied correctly, will achieve adequate fl ea control. A list of these products may be found on the Veterinary Prescriber subscription website (www.veterinaryprescriber.org). Flea resistance has been suggested as a possible factor when selecting a particular fl ea product for routine use. Despite numerous large scale studies into the

effi cacy of POMV fl ea treatments, there is currently no evidence of fl ea resistance in the fi eld. Even where resistance genes are known to exist in laboratory strains of fl ea, fi pronil, selamectin and spinosad have all been shown to be highly effi cacious at 3 weeks post application (Bass et al. 2004; Dryden et al. 2013). The presence of resistance genes in a population of fl eas may lead to a need for increased treatment frequency but this has not been demonstrated in the fi eld, with other reasons being responsible for fl ea control breakdown (Coles and Dryden 2014).

Product selection considerationsThere are a number of factors however that need to be considered when selecting a fl ea product for routine fl ea control:

Systemic absorptionSpot on preparations with systemic absorption have been on the market for many years. The introduction of spinosad (Comfortis; Elanco, Trifexis; Elanco) and the isoxazolines: afoxolaner (Nexgard/Nexgard Spectra; Merial), fluralaner (Bravecto; MSD) and sarolaner (Simparica/Stronghold Plus; Zoetis), have meant that effi cacious tablets for routine fl ea treatment have also been available. Systemic absorption is preferable if pets are frequently swimming or being shampooed. When pets are under heavy fl ea challenge from the environment, systemic absorption also ensures that there is adequate distribution of the product across the body, which can be an issue in some non-systemically absorbed spot-on preparations.

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Page 50 - VETcpd - Vol 4 - Issue 2

Speed of killKilling fl eas within 16-24 hours will prevent fl eas breeding and fl ea control breakdown occurring. In cases of fl ea allergic dermatitis (FAD) however, a faster speed of kill is desirable to reduce bites. Nitenpyram (Capstar; Elanco) has very rapid speed of kill but no persistent activity, so the arrival of products that killed fl eas rapidly and had longer duration of action were a signifi cant break through. Spinosad, the isoxazolines and indoxacarb (Activyl/ Activyl Plus; Virbac) will kill fl eas within 8 hours. Imidacloprid (Advantage; Bayer) will also reduce feeding as a result of killing through contact.

Duration of actionFlea products with varying durations of eff ective fl ea control are now available, allowing fl exibility in parasite control plans. Four weekly or monthly duration of action often fi ts in well with the need to treat monthly for endoparasites such as high risk groups for Toxocara spp. roundworm or tapeworm exposure. Some owners will prefer as long a duration of action as possible, particularly those that are on a four times a year endoparasite treatment regime. For these clients, fluralaner (Bravecto; MSD) is now available which is eff ective for 12 weeks and an imidacloprod/flumethrin collar (Seresto; Bayer) which is eff ective for up to eight months. Afoxolaner (Nexgard/Nexgard Spectra; Merial), and sarolaner (Simparica and Stronghold Plus; Zoetis) are eff ective for up to fi ve weeks, allowing some fl exibility in fl ea dosing if owners forget to treat their pets on time.

Efficacy against other parasitesWhen developing a parasite control plan for pets, other parasites that require routine treatment need to be considered in addition to fl eas. Products are available that now also treat ticks and worms that may be usefully incorporated into parasite control plans where protection against these parasites is also required.

Ticks: Systemic and repellent tick productsThere are now several fl ea products containing pyrethroids (such as permethrtin, deltamethrin and flumethrin) which repel and kill ticks.

This in contrast to the isoxazolines (Bravecto; MSD, Nexgard/Nexgard Spectra; Merial, Simparica/Stronghold Plus; Zoetis) which have recently come

onto the market and which allow ticks to feed, but kill them within 12 hours.

There has been some debate as to which is preferable in terms of reducing the risk of tick-borne disease transmission.

The predominant tick-borne disease in UK dogs is Lyme disease, transmitted by Ixodes spp. ticks (Figure 1). Ticks mostly become infected as larvae and then remain infected as nymphs and adults. When these life-cycle stages of the tick feed, Borrelia spp. multiply in the gut and, over a period of several days, penetrate the gut epithelium and migrate to the salivary glands where they may then be potentially delivered to a new mammalian host. As a result, a tick has to feed for several hours and often 24-48 hours before transmis-sion occurs. Faster transmission has been demonstrated under experimental condi-tions (Piesman 1993, Shih and Spielman 1993) but only in mice models using Ixodes Scapularis which is not present in the UK. Even under heavy challenge in mouse models, the majority of transmis-sion still took at least 24 hours to occur.

Babesia canis is now established in Essex and is capable of causing potentially life threatening disease in dogs. For this parasite, the majority of transmission is thought to occur at least 48 hours after feeding (Matjila et al. 2004).

On current evidence, tick borne pathogens endemic in the UK take at least 24 hours for the bulk of transmission to occur. Therefore, for dogs considered to be at risk of tick exposure and tick-borne diseases, a preventative product should be recommended that will rapidly kill or repel ticks. No tick preventative product is 100% eff ective but use of isoxalozines or pyrethroid containing products are is highly eff ective and will reduce disease transmission. The availability of highly effi cacious spot on, collar and tablet preparations means that owner preference and pet lifestyle can be considered when selecting a product.

Rickettsial parasites (e.g. Ehrlichia canis) may be transmitted much more quickly than Borrelia or Babesia spp., with transmission occurring within a few hours of biting having been demonstrated (Fourie et al. 2013). This risk needs to be considered in dogs travelling abroad. A tick repellent product should be applied one week before travel and cover maintained until at least one week after return.

Fly repellency is also essential for cats and dogs travelling to the South of France and Southern Europe where Leishmania infantum is endemic. Transmission occurs primarily through bites from infected phlebotomine sand fl ies (Figure 2). There are pyrethroid containing tick treatment products in dogs that are also licensed for sandfl y repellency (Advantix; Bayer, Frontect; Merial, Scalibor; MSD, Seresto; Bayer, and Vectra 3D; Ceva). Although there is no such licensed treatment for cats, Seresto collar has been shown to be effi cacious off license against sand fl ies and is safe for use in cats.

Until recently, choice of eff ective tick control products in cats was limited as pyrethroids are toxic and few safe alternatives were available. Fipronil has some effi cacy and is useful in providing a non POM-V product for tick treatment. Isoxozolines are now available as systemically absorbed spot on preparations. Fluralaner (Bravecto Cat; MSD) and sarolaner (Stronghold Plus; Zoetis) both rapidly kill ticks with a duration of action of 12 and 5 weeks respectively. Stronghold Plus also kills Toxocara spp. roundworm if monthly protection against this parasite is also required. For cats that will tolerate and keep on collars, imidacloprod/flumethrin (Seresto; Bayer) will repel and kill ticks and lasts up to eight months. These potent tick treatments in cats are important for

Figure 1: Ixodes ricinus female tick (courtesy John mcgarry,Universityofliverpool)

Figure 2: Phlebotomine sand fl y. Fly repellency is also essential for cats and dogs travelling to the South of France and Southern Europe (image courtesy of Bayer)

VETcpd - Parasitology