References
A snapshot of the adverse effects of companion animal ectoparasiticides
Abstract
The burden of ectoparasitic infestations is aggravated by the lack of vaccines and the inability to prevent the most serious vector-borne infections. This makes the administration of effective and safe ectoparasiticide drugs vital for prevention and treatment. However, adverse clinical consequences of treatment with ectoparasiticides affect many companion animals in the UK each year. In this study, information about the frequency of adverse drug events associated with the use of some ectoparasiticides in dogs and cats was collected, from data obtained from The National Office of Animal Health compendium datasheets and data available from published studies. Different ectoparasiticides were associated with different prevalences and types of adverse dermatological, gastrointestinal and neurological events. The heterogeneity between studies and the lack of field safety data for some products precludes head-to-head comparison of adverse events associated with ectoparasiticide treatment between studies. Therefore, caution should be exercised about making any conclusions when comparing ectoparasiticides. However, the data indicated an association between ectoparasiticide treatment and adverse events and demonstrated that this association can vary across different drug administration routes and classes. The low number of observations of the adverse drug events, relative to the number of administered doses, confirms that the health benefits of ectoparasiticides far outweigh the potential risks associated with their use. Further research is required on how adverse drug events can be predicted and prevented.
Infestations by ectoparasites represent a significant threat to the health and welfare of dogs and cats. Ectoparasites can cause various dermatological signs, such as pruritus, allergies and even anaemia in heavy infestations (Beugnet et al, 2014). As an example, fleas can cause irritation, pruritus, hair loss and flea allergy dermatitis (Varloud and Hodgkins, 2015). Fleas can also act as vectors of pathogens such as Rickettsia spp. and Bartonella spp. and can serve as the intermediate host of the tapeworm Dipylidium caninum (Conboy, 2009; Bitam et al, 2010). Lice infestations can result in intense irritation, pruritus, and self-trauma. Scratching can lead to alopecia, crusts and secondary bacterial involvement (Pollmeier et al, 2002). Lice can also act as vectors for various disease-causing pathogens and, like fleas, the chewing louse (Trichodectes canis) can serve as an intermediate host of D. caninum. Ticks, in addition to causing irritation, feed on the blood of their host and can subsequently cause anaemia (Varloud and Hodgkins, 2015). Ticks can carry and transmit a number of pathogens while feeding on their host (Wengenmayer et al, 2014). A number of mite genera can also cause serious welfare concerns in companion animals, including Demodex, Sarcoptes, Otodectes, Notoedres and Cheyletiella (Becskei et al, 2016). Besides causing significant morbidity and mortality among companion animals, ectoparasites have a considerable economic impact because of the costs associated with treatment and control (Rafiqi et al, 2016).
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