The demand for household pets rose abruptly throughout the COVID-19 pandemic, causing the price of new puppies to skyrocket. This rapid price increase prompted some prospective pet owners to look overseas for their four-legged friends, resulting in an influx of foreign-bred puppies and young dogs, as well as a large number of rescue dogs being moved to the UK from around the world. While many pets are imported via official routes, the high value placed upon dogs especially has prompted a surge in illegal importation of animals to sell on once they have arrived on our shores.
The need for testing
Good practice would ideally dictate that all imported pets should undergo a comprehensive series of tests and treatments prior to and upon their arrival to avert the transmission of any exotic parasites and diseases they may carry. However, there is currently no compulsory testing required for imports from EU/listed countries, and only rabies for those outside. This means that even pets imported via official means, if not screened, could act as “Trojan horses”, bringing in a multitude of potential pathogens. The risks arising from illegally imported animals, which undoubtedly will not be given the same level of care and attention, are likely to be even greater. Therefore, the rise in overall pet imports has led to a large increase in a number of exotic diseases reported in the UK.
Despite the growing importance of screening imported animals, testing may not be easily or quickly accessible from reference laboratories. A prompt accurate diagnosis is key to best support control of exotic diseases and to instigate effective measures, such as quarantine for Brucella spp. or appropriate treatment, to prevent further spread. Furthermore, an extended wait for results may not only amplify the likelihood of zoonotic disease transmission, but also give rise to an increased risk of poor outcomes for animals.
How serious is this issue, what should we look out for, and what steps are being taken to help overcome the rise of exotic pathogens in UK pets?
These were points of discussion in a recent free CPD webinar offered by the veterinary team at HORIBA UK and delivered by parasitology expert Ian Wright, MRCVS and head of the European Scientific Council for Companion Animal Parasites (ESCCAP) UK & Ireland. The webinar aimed to provide education and support to veterinary professionals and to highlight the importance of testing in imported pets, particularly dogs.
The dangers posed by exotic ticks
Ticks represent one of the primary vectors of exotic disease transmission in dogs (Figure 1). Tick-borne pathogens increasing in incidence include Anaplasma platys, Hepatozoon canis, Ehrlichia canis and Babesia spp. Each of these pathogens can cause severe and long-lasting health implications for dogs, giving rise to conditions such as canine monocytic ehrlichiosis, babesiosis and anaemia, which can be life-threatening if not detected and treated early enough.
Also of concern are Ixodes spp. ticks, which are carriers of dangerous pathogens including Borrelia burgdorferi, which gives rise to Lyme disease, and tick-borne encephalitis virus (TBEV). TBEV is especially dangerous, as it can cause severe acute illness and carries a zoonotic risk. Other parasites of concern that are on the rise in the UK include Leishmania infantum and Brucella canis, as well as fly-borne nematodes such as Dirofilaria immitis (heartworm).
A significant issue presented by exotic ticks is that the pathogens carried could become endemic to the UK, passing into our indigenous tick populations and resulting in large swathes of UK pets at risk of tick-borne conditions previously not native to us.
The UK government last year launched a public consultation on proposed rule changes to raise welfare standards and crack down on the illegal importation of cats, dogs and ferrets
With so many animal welfare issues arising around imported pets, including the increase in exotic pathogens, the UK government last year launched a public consultation on proposed rule changes to raise welfare standards and crack down on the illegal importation of cats, dogs and ferrets. ESCCAP UK & Ireland wants the government to go further and has made calls for compulsory testing of imported dogs for exotic pathogens, especially those with zoonotic capabilities.
What is being done to tackle this problem?
To better regulate the importation of pets, ESCCAP UK & Ireland has posited four core factors (ESCCAP UK & Ireland, 2021) to consider when processing imported pets on arrival in the UK. The first of these pillars is to check for ticks and identify any found. The identification of ticks allows for the close monitoring of exotic tick species being imported, and also gives an indication of any candidate tick-borne diseases that the imported pet could have been exposed to.
The identification of ticks allows for the close monitoring of exotic tick species being imported, and also gives an indication of any candidate tick-borne diseases that the imported pet could have been exposed to
ESCCAP also recommends screening and testing for parasites and pathogens in imported dogs to ensure early diagnosis of exotic infection. This not only supports the prevention of the establishment and internal transmission of novel exotic parasites in the UK but can also give a dog the best chance of a good prognosis if disease is present. Furthermore, screening can provide owners with vital knowledge of long-term health implications, the required treatment plan, any potential zoonotic risks and their management.
Typical screening protocols
Exotic diseases can present a substantial diagnostic challenge for veterinarians, as their clinical signs may be widespread and overlapping. In addition, co-infections with two or more pathogens are not uncommon, and enhance this problem further (Andersson et al., 2017). While ESCCAP appreciates the difficulties associated with gaining a deep understanding of every exotic pathogen that may be encountered, by identifying the key clinical presentations and coupling these with screening tests we can maximise the chances of pathogen detection and management. To help veterinarians apply the correct screening process for the most common exotic pathogens found in dogs, ESCCAP has created a useful guide outlining proposed testing methods (Table 1).
|Leishmania||Quantitative serology, PCR|
|Dirofilaria immitis (heartworm)||Antigen blood test, Knott’s test|
|Ehrlichia canis||Serology, PCR|
|Anaplasma platys||Serology, PCR|
|Hepatozoon canis||Blood smear, PCR|
|Brucella canis||Consult external lab for suitable test – PCR, serology|
Core diagnostic tests for tick-borne pathogens generally involve blood smears, serology or polymerase chain reaction (PCR) testing. Blood smears are a rapid and easy tool but come with a limited sensitivity of around 4 percent or less for most tick-borne pathogens. However, blood smears can be particularly effective for detecting Hepatozoon canis, which presents with large numbers of distinctive gametocytes (Figure 2). Serologic testing has proven to be a useful application for the detection of Ehrlichia and Anaplasma species, but detectable levels of antibody can remain in the serum long after infection, so can yield false-positive results. PCR is an extremely powerful diagnostic tool which, due to its high sensitivity and specificity in most cases, is able to identify very low levels of pathogen, making for a ubiquitous and versatile screening method.
Although PCR represents an extremely useful diagnostic tool in the screening of imported pets, very few veterinary practices currently have PCR testing facilities in-house. This results in most samples being sent off to third-party reference laboratories for testing, which may mean that the potential for in-house PCR tests is overlooked.
To speed up diagnosis and minimise zoonotic risk, there is a need for more economical in-house PCR testing options which can rapidly deliver highly specific and sensitive results for a variety of diseases.
In-house PCR solutions
Aware of the desire for fast, easy-to-use in-house PCR solutions, HORIBA has introduced the POCKIT Central (Figure 3), a benchtop instrument which can provide rapid and reliable PCR testing for veterinary laboratories and practices of all sizes. The POCKIT Central can complete a PCR screening in just 85 minutes, negating the wait for results from third-party reference laboratories.
The hugely improved time from sample to result is possible due to the POCKIT Central’s integrated PCR workflow from nucleic acid extraction to amplification, reaction and reading. The simple user interface and test process make PCR testing accessible to all practices and members of the team. Full staff training and support is provided by HORIBA via its own team of veterinary product specialists and technical staff, who can complete a system installation within 30 minutes.
A simple, automated solution such as HORIBA’s POCKIT Central technology will empower veterinary practices to employ increased PCR testing, complementing and enhancing their existing in-house facilities
The POCKIT Central offers over 190 assays, with the capacity to simultaneously screen for up to eight pathogens in one run. The test range includes Babesia gibsoni, Dirofilaria immitis, Ehrlichia canis, Leishmania, Brucella spp. and Lyme disease, along with the more commonly seen canine and feline pathogens. In addition to small animal testing, the novel in-house PCR system also has tests tailored for equine and farm practice, with specialist assays also available for poultry and aquaculture.
A simple, automated solution such as HORIBA’s POCKIT Central technology will empower veterinary practices to employ increased PCR testing, complementing and enhancing their existing in-house facilities. In turn, this could significantly improve capabilities for exotic disease screening and the health outcomes of imported pets, while reducing the zoonotic risk to owners and veterinary practitioners alike.
Exotic pathogens from imported pets pose a health risk to UK animals, their owners and our biosecurity. Consequently, measures such as the four pillars proposed by ESCCAP UK & Ireland should be employed in order to tackle this issue, including the need for high-quality routine screening. Along with regular veterinary parasite treatment, this remains the best way to guard against exotic parasites and the diseases that they may cause. Innovations such as HORIBA’s POCKIT technology represent a valid solution to this problem, now making in-house PCR testing a real option.
|The webinar “Exotic parasites – the importance of testing in the imported dog”, presented by Ian Wright, BVMS, MSc, MRCVS, Head of ESCCAP UK & Ireland, is available to watch on demand at: https://www.horiba.com/int/veterinary/support/webinars/exotic-parasites/ along with other HORIBA free veterinary CPD webinars. With thanks to Ian Wright.|