Canine and Feline Parasite Control at Home and Abroad
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Vet Times The website for the veterinary profession https://www.vettimes.co.uk Canine and feline parasite control at home and abroad Author : Ian Wright Categories : Companion animal, Vets Date : June 13, 2016 ABSTRACT The European Scientific Counsel Companion Animal Parasites (ESCCAP) UK and Ireland is a national association of ESCCAP Europe, bringing together some of the UK and Ireland’s leading experts in the field of veterinary parasitology. ESCCAP UK and Ireland works with pet owners and professionals to raise awareness of the threat from parasites and provide relevant information and advice. Part of this service is to answer questions from the public and veterinary professionals asked via www.esccapuk.org.uk This article addresses the most common questions asked that are of particular relevance to veterinary professionals. The European Scientific Counsel Companion Animal Parasites (ESCCAP) UK and Ireland is a national association of ESCCAP Europe, bringing together some of the UK and Ireland’s leading experts in the field of veterinary parasitology. 1 / 11 Figure 1. Flea bite reaction. ESCCAP UK and Ireland is independent, working with pet owners and professionals to raise awareness of the threat from parasites and provide relevant information and advice. Part of this service is to answer questions from the public and veterinary professionals, asked via www.esccapuk.org.uk Some questions are specific to individual circumstances, such as trematodes present in Asia and parasites present in the Middle East. Others, however, are asked frequently and of more general relevance to UK veterinary professionals. Some examples are discussed in this article and fall into four broad categories: ectoparasite control in households macrocyclic lactone use European pet travel advice Babesia canis prevention in dogs Ectoparasite control in households Questions are often asked about parasites found in the home – either when life stages are discovered in the house or when ectoparasites are found on pets. How do I deal with fleas biting me in my home? 2 / 11 People are most commonly bitten by cat fleas emerging from pupae and feeding for the first time. Although they cannot survive on people, they can inflict bites with significant skin reactions (Figure 1). These bites can occur from flea infestations being maintained by the owner’s pets, stray cats or wildlife entering the home, or when people enter homes that have been vacated for long periods with pupae lying dormant. If people in the household do not own pets and bar entry to other animals entering the home then environmental treatment alone will rapidly reduce the number of bites. This may also be required if the home is invaded by avian fleas from abandoned nests in attic spaces or chimneys. Pyrethroid sprays containing growth inhibitors are effective, but if the source of the infestation is not clear, whole house fumigation may be required. If pets are present in the home to allow flea reproduction then a multiple-pronged strategy is required. Adulticide Using an effective adulticide can prevent egg laying and break the reproductive cycle. Adulticides must kill 100% of fleas before they can lay eggs. Adult fleas can lay eggs within 24 hours, so an effective flea treatment must kill fleas at least within that time. They must also be administered frequently enough to continue to prevent egg laying. The time after application at which fleas survive long enough in the presence of the product to lay eggs is known as the “reproductive break point”. If the reproductive break point is reached then flea control will fail. Effective environmental control 3 / 11 Figure 2. Book lice. Directly reducing the numbers of eggs, larvae and pupae in the environment will decrease the time required to bring an infestation under control. This may be achieved using environmental sprays containing a pyrethroid, such as permethrin or deltamethrin (both for dogs), and a growth inhibitor. Lufenuron can also be used in pets systemically to prevent flea eggs from hatching. Some adulticide flea treatments, such as imidacloprid and selamectin, will subsequently be shed into the environment, reducing environmental egg and larval contamination. Many spot-on flea products also contain growth regulator S-methoprene to achieve a similar effect. Daily vacuuming of areas frequented by infested pets has also been demonstrated to reduce pupae in the environment. Flea infestations take at least three months to eliminate – often much longer – with nine-month treatment regimens often required (Dryden et al, 2000). This needs to be made clear to clients so they are prepared for long periods of treatment before fleas are eliminated – and so they do not rapidly become disheartened. It is also important to establish whether fleas are present at all. Insect life stages have been presented to the author, which owners believed to be parasitic life stages attacking them in the home. Examples are book lice (Figure 2), which look like bed bugs, but are, in fact, free-living insects. They congregate around food bowls, making pet owners sometimes think they are fleas or lice. Plant seeds (Figure 3) may sometimes be mistaken for flea eggs and flea larvae (Figure 4) are sometimes presented in the belief they are attacking owners. Although this life stage feeds on detritus and flea dirt, it is a sign flea infestation is present in the home. 4 / 11 Adult cat fleas may be identified by their laterally flattened appearance and head combs (Figure 5). Can ticks infest my home like fleas? Ixodes species ticks are predominant in the UK and have a life cycle of three years. In temperate climates, each life cycle feeding stage does so only once per year, so takes three years from egg to adult. The larval stage that feeds in the first year requires small hosts, such as rodents and songbirds. As a result of these factors, it is unlikely Ixodes ticks will establish in UK homes and exposure takes place primarily outdoors. Figure 3. Plant seed casing. Dermacentor and Rhipicephalus species have similar life cycles, with the potential to complete them more quickly; in the case of Rhipicephalus, often within one season. This allows it to potentially take advantage of increased temperatures in central-heated homes and become established in households in a similar way to fleas. It has not yet formed endemic foci in the UK, but two cases of house infestation have been recorded in south England (Hansford et al, 2015). These cases were from dogs imported from Europe and at least one had been tick-treated before admission. 5 / 11 Nymphs of Rhipicephalus survived and, once established, took more than 12 months to eliminate, despite effective tick treatment of pets and repeated fumigation of the house. This demonstrates both the importance of checking dogs that have been tick-treated for ticks and also rapid reporting and identification of ticks found in the home. Macrocyclic lactone use Can you use milbemycin oxime or moxidectin in collies/related breeds? Concern exists among veterinary professionals and the public regarding the use of macrocyclic lactones (avermectins and milbemycins) in collies and related breeds. This is due to these breeds carrying the multi-drug resistance one (MDR1) gene, making them susceptible to ivermectin crossing the blood-brain barrier. However, licensed macrocyclic lactones – including moxidectin, milbemycin and selamectin – have all been demonstrated to be safe in collies (see individual data sheets). The safety margin of overdose is narrower in these breeds, however, so it is important to dose accurately and make owners aware of the risk of overdose. They should also be avoided in these breeds where therapeutic indication is to use them at increased frequency, such as weekly use of moxidectin for treatment of Demodex. Can moxidectin and milbemycin be used together? The popularity, high efficacy and good compliance with many clients achieved with tablets containing milbemycin oxime and spot-on preparations containing moxidectin, has led to a desire to use them together. However, the two drugs are not licensed to use together in any formulation and, so far, safety data is limited to small case studies. Even if larger studies demonstrating safety were published, without a license it is hard to justify their combined use, given the similar spectrums of activity. Both being milbemycins, they are very closely related, making the possibility of combined overdose more likely. This is of particular concern in collies and other dogs carrying the MDR1 gene, where macrocyclic lactones already have a narrower margin of safety. One argument for combined usage is the addition of praziquantel in many milbemycin tablet products. A wide variety of tablets containing praziquantel without milbemycin are available, if moxidectin spot-on preparations are preferred and tapeworm treatment is required. No grounds exist, therefore, on which combined use can be justified and if there was an adverse 6 / 11 reaction to their combined use then defending this course of action would be difficult. On evidence, ESCCAP UK and Ireland can, in no way, support their combined use. European pet travel advice ESCCAP UK and Ireland receives frequent questions surrounding pet travel. The most common are regarding tapeworm and tick travel requirements under the Pet Travel Scheme (PETS) and confusion around travel to the Republic of Ireland. Are tapeworm and tick treatments still a PETS requirement? Tick treatments have ceased to be compulsory for dogs travelling to the UK. This is perceived to have been a factor in the establishment of Rhipicephalus sanguineus in households in south England and in the introduction of babesiosis to the UK. Although it is likely maintaining the compulsory treatment would have slowed down the introduction of foreign ticks and tick-borne diseases affecting canids, this is not why it was established. Like all compulsory PETS treatments, it was put in place to stop human tick-borne disease entering the country – primarily Mediterranean spotted fever caused by Rickettsia conorii.