Taking pets abroad
For pet owners taking their pets to mainland Europe, there is a need to comply with Pet Travel Scheme rules on rabies immunisation and tapeworm therapy. But the scheme does not take account of other parasite threats that might be encountered and that might affect the pet's health. This month’s module covers the four main parasite threats that dogs, cats or ferrets might encounter. By doing this module you will:
know the main parasite risks for pets visiting mainland Europe;
know where to find information about parasite distribution;
understand the drug and non-drug measures for reducing risk of infection;
be able to make a rational choice of parasiticide products.
There will be a module on imported pets later in the year.
When travelling from Great Britain or Ireland to mainland Europe, pets may be exposed to a wide range of exotic parasites. This module focuses on control strategies for four parasites that are of particular concern because they can cause serious disease in people or pets. While the Pet Travel Scheme demands that dogs receive therapy to prevent the introduction of the tapeworm Echinococcus multilocularis, because of the risk to human health (Gov.UK 2011), it is important for vets to consider, and advise pet owners about, protecting travelling pets against the three other main parasite threats: the heartworm Dirofilaria immitis; ticks and tick-borne diseases; and the protozoan Leishmania infantum.
The tapeworm E. multilocularis is the cause of cystic echinococcosis, a severe zoonosis. The adult tapeworm is carried by domestic dogs, foxes (which act as a reservoir of infection) and microtine voles (intermediate hosts). Dogs and foxes become infected through predation of voles. Cats can also act as definitive hosts for E. multilocularis but have a lower worm burden with lower fecundity than canids, making them less likely to be a significant source of infection. The tapeworm does not usually cause disease in pets but eggs passed in the faeces of dogs and foxes are immediately infective. People can become infected after ingestion of the eggs, through association with infected dogs, via public spaces contaminated with dog faeces, or by eating contaminated raw fruit and vegetables. Infection results in local and metastatic spread of cysts leading to liver dysfunction and potential multiple organ involvement.
Over the last two decades, the tapeworm has spread from its focus in Eastern France, southern Germany and parts of Switzerland and Austria, to Baltic regions, Denmark, the Netherlands, Poland, Romania, Slovakia and Slovenia (Oksanen et al. 2016). Also, the incidence of human echinococcosis has increased in some countries. The map shows the range of E. multilocularis (ESCCAP). In Europe, only Great Britain and Ireland, Malta, Finland and Norway have endemic-free status (Oksanen et al. 2016). An increase in pet travel, the spread of the parasite across Europe, and the reduction (in 2012) in the interval allowed between tapeworm treatment and the return of dogs to the UK (from 1–2 days to 1–5 days) potentially threatens this status.
D. immitis is a filarial heartworm. It mainly infects canids but it can also infect ferrets and felines. It is a significant cause of heart disease in infected cats, dogs and ferrets, and of bronchitis in cats. Transmission occurs through feeding by infected mosquitoes. Acute clinical signs are a result of migration of larvae to the pulmonary artery; chronic signs are due to inflammatory responses to migrating larvae and aberrant migration. The parasite is endemic throughout southern Europe and has spread into eastern European countries such as Romania and Bulgaria. The map shows the range of Dirofilaria in Europe (ESCCAP). The worm is not endemic in the UK. Although the mosquito vectors are endemic in most European countries, including the UK, a colder climate in northern Europe has prevented heartworm from becoming endemic because the adult mosquito does not live long enough for heartworm to complete its lifecycle. However, climate change is enabling the spread of the parasite northwards, raising the possibility that endemic foci could establish in southern England.
Pets travelling abroad may come into contact with a variety of tick-borne diseases that are not thought to be endemic in the UK. The following are of particular concern because they have been found in the UK or represent a serious zoonotic risk.
The protozoan parasite Babesia canis, which can cause life-threatening anaemia in dogs, is now endemic in most of Europe. Pockets of the vector tick Dermacentor reticulatus have long been established in several areas in the UK. These ticks present an opportunity for B. canis to become endemic if introduced by dogs arriving from abroad. There is evidence that this may be starting, because there are now endemic foci of B. canis infection in Essex, and B. canis has been confirmed in local Dermacentor ticks (Phipps et al. 2016; Woodmansey 2016). The potential for spread of the disease is shown by confirmation of B. canis in a tick from one of the endemic foci in Wales (de Marco et al. 2017).
The tick Ripicephalus sanguineus is capable of carrying a wide range of diseases pathogenic to dogs, including erlichiosis. The tick’s range has been restricted to warmer climates in southern Europe. In 2017, the European Scientific Counsel for Companion Animal Parasites (ESCCAP) UK & Ireland reported an increased number of Ehrlichia canis cases transmitted by R. sanguineus in travelled dogs (Ian Wright – personal communication). Untravelled cases of Ehrlichia canis have been reported in France, Switzerland and Austria. The requirement for dogs entering the UK to be treated for ticks was dropped from the Pet Travel Scheme in 2012 because the risk of R. sanguineus establishing in the wider environment in UK was judged to be negligible (Gov.uk 2011). Although it is unlikely that the tick would establish outdoor endemic populations in the UK, it can complete its lifecycle in 3 months, which is sufficiently fast to allow it to infest centrally-heated UK homes. This is a concern, because these ticks may carry zoonotic pathogens such as Rickettsia conorii (the cause of Mediterranean spotted fever). The number of reports of R. sanguineus in the UK received by the UK tick surveillance scheme appears to be increasing each year and in recent years there have been two confirmed house infestations (Hansford et al. 2017).
Tick-borne encephalitis is a viral disease primarily transmitted by Ixodes ricinus ticks. The virus may infect a variety of mammalian hosts including dogs, foxes and ruminants. It is a potentially severe zoonosis with infections most commonly resulting in a transient fever, but sometimes progressing to meningioencephaltitis. Although human infection is uncommon, it can be fatal and so concern about its spread through Europe has been high. In Europe, the virus is a parasite predominantly of Eastern countries but its distribution has been moving north and west, with cases emerging in Scandinavia (Pettersson et al. 2014). I. ricinus is endemic in the UK so infected ticks or pets entering the country could potentially lead to establishment of infection in native ticks.
A Hyalomma lusitanicum tick was recently found on a dog in the UK imported from Portugal (Hansford et al. 2016). This species of tick is a potential vector of Crimean-Congo haemorrhagic fever virus, which is highly pathogenic in people.
Leishmaniosis is caused by intracellular protozoan parasites of the genus Leishmania. In cats and dogs Leishmania infantum is the predominant species. It has zoonotic potential and is a significant endemic zoonosis in southern Europe. Transmission occurs primarily through bites from infected phlebotomine sandflies. This has limited the distribution of the parasite to the south of France and southern Europe. However, large numbers of cases are being seen in the UK in imported and travelled pets. Rapid diagnosis of infection is important because transmission can also occur through blood transfusion, and vertical and venereal transmission. Canine and feline leishmaniosis are chronic in nature with a variety of presentations and periods of remission. Signs are due to immune complex deposition in various organs. The sandfly vector for Leishmania infantum is not present in the UK so endemic establishment is unlikely. However, the disease has established in countries such as Canada, with no sandfly vector, through venereal transmission. ESCCAP UK and Ireland reported an increased number of L. infantum cases in travelled dogs in 2017.
Veterinary practices in the destination of travel will have local knowledge of endemic parasite foci and seasonal transmission, as well as peak activity times of local mosquitoes and tick vectors. Maps describing European parasite distributions by country are on the ESCCAP and ESCCAP UK & Ireland websites (www.esccap.org and www.esccapuk.org.uk).
The UK Pet Travel Scheme requires that dogs are treated for tapeworm before entry into the UK. Vets can advise clients on optimal use of this tapeworm therapy and on reducing the risk of the three other main parasite threats to pets.
Praziquantel is the drug of choice for control of E. multilocularis (ESCCAP 2018). The Pet Travel Scheme requires that all dogs entering the UK are treated between 1 and 5 days before entry, unless returning from Finland, Ireland, Malta or Norway. Dogs must be treated by a vet using a product licensed in the country in which the dog is treated. A record of the treatment must be made in the pet passport or certificate. However, the short half life of praziquantel (4–6 hours) means there is a theoretical risk of infection between the time of treatment and return to the UK. Therefore parasitiologists recommend that dogs should be treated again within 30 days of return to the UK to ensure any infection that has occurred in the short gap is eliminated (ESCCAP UK & Ireland 2018). Dogs infected while abroad will shed eggs in their faeces after 30 days, so presenting a severe zoonotic risk to their owners. Dogs on long stays should therefore be treated with praziquantel every 30 days while abroad. For short trips, the Pet Travel Scheme requires the dog to be treated by a vet before leaving the UK and not to return for at least 24 hours. If the return is more than 120 hours later, a further treatment is required abroad. Dogs must be treated again within 30 days of returning to the UK.
Praziqauntel products: There is a wide range of licensed products for dogs, containing praziquantel alone (tablets or injection) or together with another endoparasiticide; products containing milbemycin also cover heartworm. (See the table below showing product choice).
Heartworm (Dirofilaria immitis)
Prophylactic therapy with a macrocyclic lactone to reduce the risk of adult infection establishing should be started before travel and continued monthly until return to the UK. For dogs there is a choice of licensed products in the form of tablets or spot-ons; some tablets also cover ticks and some also cover tapeworm. For cats there is a choice of spot-ons (that also provide cover for ticks or tapeworm) or tablets. For ferrets there are spot-ons. Mosquito repellents will act as a useful second line of defence, but should not be solely relied upon. There are several spot-on products and a collar licensed for dogs. (See the table under Leishmania infantum below).
Ticks and tick-borne diseases
On current evidence, transmission of most tick-borne pathogens affecting cats and dogs in Europe is thought to take at least 24 hours (Little 2007). Although not a requirement of the Pet Travel Scheme, use of an effective tick control product is recommended by parasitologists.
Suitable products contain an acaricide with proven fast-acting effect (i.e. the isooxazoline drugs – afoxolaner, fluralaner or sarolaner), or a pyrethroid acaricide and repellent (i.e. deltamethrin, flumethrin or permethrin). As E. canis can be transmitted within a few hours of a tick bite (Fourie et al. 2013), if travelling in countries where R. sanguineus is endemic, it is logical to prefer a tick repellent (a pyrethroid). No tick product is 100% effective and so pet owners should check their animal for ticks regularly and remove any found. Pyrethroid products, which are all used topically, should be started 1 week before travel because the drug will take time to distribute over the body.
Acaricide and tick-repellent products. For dogs there are tablet formulations, and also licensed collars and spot-on products (some of which also cover mosquitoes and sandflies). For cats there is a collar and spot-on product. See the tables below.
Parasitologists consider disease prevention essential for dogs travelling to endemic countries. This involves using a pyrethroid (i.e. deltamethrin, flumethrin or permethrin) to prevent sandflies from biting. The treatment should be started 1 week before travel because pyrethroids, which are all used topically, take time to distribute over the body. No fly repellent is 100% effective and so other preventative measures should also be used for dogs and cats travelling frequently or for long periods in endemic countries.
Pyrethroid products. There are several collars and spot-on products licensed for dogs, all of which are also effective against ticks. See the table. Flumethrin + imidacloprid (Seresto) collar is not licensed as a sandfly repellent. However, there is evidence from a controlled trial involving 224 dogs in Sicily that it was effective in preventing L. infantum infection (Brianti et al 2016). It may therefore be an option for animals for which the licensed products are unsuitable.
Other measures can be used in addition to preventative treatments, to help reduce exposure to parasitic diseases or development of disease while abroad.
Preventing predatory and scavenging behaviour – Dogs and cats become infected with E. multilocularis through consumption of prey animals, so preventing this will halt transmission. Given the severity of the zoonosis, this should never be relied upon alone but used as a secondary preventative measure.
Checking for ticks at least every 24 hours – Even if preventive treatment is used it is important that pet owners check pets for ticks daily, removing any with a tick removal device or fine-pointed tweezers.
Insect avoidance strategies - Sandflies feed at night and are most active at dawn and dusk, so avoiding outdoor activity at these times helps to prevent exposure. They are also poor flyers, so sleeping with pets upstairs at night, if possible, is sensible. If camping outdoors, breezy high locations are better. Fine-mesh insecticide-impregnated bed nets also help limit canine exposure at night, but are unsuitable for cats.
Leishmaniosis vaccine - A vaccine (CaniLeish) is licensed for use in dogs from 6 months of age. The summary of product characteristics states that the vaccines reduces the risk of active infection (by a factor of 3.6) and clinical disease (by a factor of 4) (CaniLeish SPC). A serological test for Leishmania infection is recommended before vaccination in dogs that have travelled abroad because the efficacy of the vaccine in already infected dogs is not known. The vaccine must not be used in place of measures to prevent exposure to sandflies because it does not prevent initial Leishmania infection.
The increased movement of pets and changing vector and parasite distributions in Europe make protecting UK pets and owners from exotic disease increasingly challenging. Vets and vet nurses must be prepared to give accurate advice on parasite protection to people intending to travel with their pets to mainland Europe. This will help protect individual pets and owners while also helping to prevent establishment of new parasites and vectors in the UK.
To protect against the tapeworm Echinococcus multilocularis, dogs must be treated with praziquantel 1 to 5 days before return to the UK (a requirement of the UK government’s Pet Travel Scheme). Returning dogs should also receive a further dose of praziquantel 30 days after return. Dogs staying on the European mainland should receive monthly doses of praziquantel.
To protect against ticks and tick-borne diseases, a product containing an isooxazoline or a pyrethroid should be started about a week before travel. A pyrethroid product is preferable for travel to Erlichia canis endemic areas.
To protect against heartworm, a product containing a macrocyclic lactone is needed.
To protect against Leishmania infection a sandfly repellent (pyerthroid) is needed.
Protection from disease may be enhanced by considering adjunctive measures, including checking for ticks, insect avoidance and vaccination against Leishmania.
If you prefer, you can listen to the whole audio presentation of this module using the following podcast. Don't forget that you can also download the podcast to your iPod, music player, tablet or smartphone using the Download link on the right of the audio player.
Click the play button below to answer the multiple choice questions on this module. Start by entering your first and second names and your email address so we can send you a CPD certificate for your records.
Goal of activity: Update knowledge; help clinical decision-making.
Specific learning objectives: to improve knowledge and understanding of parasite protection in animals travelling to mainland Europe.
How we produced this module
Our modules start with a detailed outline and electronic literature search. We commission a collaborating author, who is a specialist in the module topic, to write a draft module. The collaborating author on this module was Ian Wright. The draft is circulated unsigned to a wide range of commentators, include practising first-opinion vets, other topic specialists, the companies that market any mentioned drugs and other organisations and individuals, as appropriate. They can raise points about the interpretation of evidence, ask questions that are important to clinical practice, and present alternative viewpoints. There is a rigorous editing and checking process and the result is a module that is evidence-based, impartial and relevant to clinical practice. The final module is unsigned because it is the result of collaboration.
Brianti E et al. Field evaluation of two different treatment approaches and their ability to control fleas and prevent canine leishmaniosis in a highly endemic area. PLOS Neglected Tropical Diseases 2016: doi :10.1371/journal.pntd.0004987.
de Marco M et al. Emergence of Babesia canis in southern England. Parasit Vectors 2017; 10: 241.
ESCCAP UK & Ireland. Echinococcus multilocularis treatment on return to the UK [website]. [Accessed 14.2.18].
ESCCAP. Worm control in dogs and cats. ESCCAP Guideline 01 Third Edition – July 2017.
Fourie JJ et al. Transmission of Ehrlichia canis by Rhipicephalus sanguineus ticks feeding on dogs and on artificial membranes. Vet Parasitol 2013; 197: 595-603.
Department of Environment, Food and Rural Affairs. New rules mean it will be easier and cheaper to travel abroad with pets, 2011 [online press release]. (Accessed 14.2.18)
Hansford KM etl al. Importation of a Hyalomma lusitanicum tick into the UK on a dog. Vet Rec 2016; 179: 415.
Hansford KM et al. Potential risk posed by the importation of ticks into the UK on animals: records from the Tick Surveillance Scheme. Vet Rec 2017: doi: 10.1136/vr.104263.
Little SE. Changing paradigms in understanding transmission of canine tick-borne diseases: the role of interrupted feeding and intrastadial transmission. Proceedings of the 2nd Canine Vector-Borne Disease (CVBD) Symposium; 2007 April 25-28; Mazara del Vallo, Sicily, Italy. Germany: Bayer HealthCare; 2007. P. 30–4.
Oksanen A et al. The geographical distribution and prevalence of Echinococcus multilocularis in animals in the European Union and adjacent countries: a systematic review and meta-analysis. Parasit Vectors 2016; 9: 519.
Pettersson JH-O et al. Prevalence of tick-borne encephalitis virus in Ixodes ricinus ticks in northern Europe with particular reference to Southern Sweden. Parasit Vectors 2014; 7: 102.
Phipps L et al. Babesia canis detected in dogs and associated ticks from Essex. Vet Rec 2016; 178: 243-4.
Woodmansey D. ‘New tick-borne disease confirmed in UK dogs’. Veterinary Times 2016; 46: 1