Page 106 - WSAVA2017
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An Urban Experience
I. Wright1
1ESCCAP, UK & Ireland, Malvern, United Kingdom
Ian Wright BVMS.Bsc. Msc. MRCVS
The Mews Studio, Portland Road, Malvern, Worcs, WR14 2TA, UK
Contact e mail –
Since the introduction of the Pet Travel Scheme (PETS), pet travel throughout Europe and the exchange of pets between countries has increased. This has occurred
at a time of increased human migration and climate change, providing favourable conditions for the rapid spread of parasitic diseases and their vectors. Parasites considered as Southern European infections such
as Dirofilaria immitis and Leishmania infantum are increasingly presenting in Scandinavian Veterinary clinics in travelled or imported pets. In addition, parasites not previously seen in Europe such as Linguatula serrata are also becoming increasingly prevalent and may be seen in imported animals.
Veterinary professionals must therefore be aware of exotic pathogens being present in these pets, be able to recognise relevant clinical signs and rapidly diagnose infection. This will improve prognosis in individual pets and reduce the risk of exotic parasites establishing new endemic foci.
Dirofilaria immitis (heartworm)
D.immitis is a filarial heartworm primarily of canids
but also can infect ferrets and felines. It is endemic throughout Southern and Eastern Europe, and is a significant cause of heart disease in infected pets, and of bronchitis in cats. Transmission occurs through feeding by Culicine mosquitoes. Acute clinical signs occur through migration of larvae to the pulmonary artery, potentially leading to thromboembolism, Caval syndrome and subsequent pulmonary hypertension. Worm death can lead to anaphylaxis and thromboembolism. Typical resulting acute clinical signs include sudden death, anorexia, weakness, dyspnoea, a jugular pulse and a weak femoral pulse, anaemia, haemoglobinuria, vomiting and rarely pleural effusion.
Chronic signs are due to inflammatory responses in response to migrating larvae and aberrant migration. These tend to be respiratory in nature and include
coughing, dyspnoea, anorexia, vomiting and rarely chylothorax. Chronic respiratory signs tend to be more common in cats.
Although it is not endemic in Scandinavia, increasing numbers of Scandinavian pets are travelling to, and being imported from endemic countries. Although the culicine mosquito vector is endemic in most European countries, a colder climate in Northern Europe has prevented heartworm from becoming endemic. This is because the development of Dirofilaria microfilariae to the L3 larval stage requires 29 days at a constant 18 degrees centigrade (Lloyd, 2011). Climate change however, has allowed spread of the parasite northwards, raising the possibility that if this trend continues, that endemic foci could establish in parts of Southern Scandinavia. The Climate Division of the Norwegian Meteorological Institute reported that in certain parts of the country, the average temperature could be sufficiently high enough to allow development of the D.immitis larvae to reach the infective L3 stage in Norwegian mosquito species and endemic foci along the coast of southern Norway potentially be established. Blood antigen testing on 80 dogs imported into Norway from Eastern Europe found 7.5% to be positive for D.immitis, suggesting that a significant number of infected dogs are entering the country. This picture is also likely to be similar in other Scandinavian countries (Vatne, 2014).
For this reason, Veterinary professionals must be aware of the possibility of infection in pets imported from Southern and Eastern Europe, or that have visited there. Pets having visited endemic countries need to be tested for heartworm if they have not been on preventative treatment so decisions can be made regarding future treatment and the risk of mosquito vectors being exposed to infection can be reduced.
A number of diagnostic test are available for heartworm diagnosis
• Examination of blood for microfilaria – Direct smears are a highly specific test in experienced hands but also insensitive. Concentration techniques including filtration methods, Knott’s test (a form of sedi- mentation test) and buffy coat examination make direct blood exam- ination more sensitive in canine patients but still extremely insensitive in the cat due to low circulating levels of microfilariae. If microfilariae are detected, the larvae must be distinguished from D.repens (table 1) which will also be present in endemic countries.
• Ultrasound examination – The cuticles of adult heart worms are highly echogenic and so in experienced hands echocardiography can be very sensitive and specific. However, in cases with low burdens or with inexperienced ultranosographers sensitivity will decrease.
• Antigen Serology – This test is considered the gold standard in the living canine patient. It is highly specific and in canine patients, also highly sensitive. Although specificity still approaches 100% in

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