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Quantitative serology is a sensitive and specific test for infection. Measuring quantitative serology over time can give an early warning of clinical leishmaniosis if antibody levels are climbing. PCR is also a useful test but carries a low sensitivity if blood is used. Conjunctival swabs give a higher sensitivity and are non invasive but many dogs that have lived in endemic countries for years will be positive and PCR gives no indication of the significance of infection in the sub clinical patient. PCR and histopathology of clinically affected skin and lymph nodes is useful to confirm infection as the cause of the clinical presentation.
Due to the ongoing risk that imported parasites represent to individual pets, owners, the wider public and UK biosecurity as a whole, ESCCAP UK & Ireland recommend four key steps (the ‘four pillars’) when dealing with all imported or travelled pets arriving in the UK:
Angiostrongylus vasorum is now endemic in foxes across the UK but with a patchy distribution. It should be considered as a differential for coagulopathies, respiratory signs, neurological disorders and heart disease in any part of the country. Testing cases with relevant signs and sharing case information remains the best way to assess geographic risk and fluid rates of exposure in local areas. A point-of-care blood test which detects circulating A.vasorum antigen in the blood (Angiodetect®) allows for a more rapid diagnosis in a clinical setting and also allows many dogs with clinical signs compatible with A.vasorum infection to be tested relatively economically and rapidly. This in turn allows a picture within practices to be built up as to whether A.vasorum is a present in the local area. This picture needs to constantly updated however as the regional prevalence of A.vasorum can change rapidly. Case maps with collated national reported data are also available such as the one from Bayer https://www.vetcentre.bayer.co.uk/campaigns/be-lungworm-aware/lungworm-map/
The most important aspect of flea control is to ensure adult fleas are killed on the pet before they can initiate egg production. Treatment of the environment with insect growth regulators, environmental insecticides, hot washing of bedding and daily vacuuming is also important to reduce environmental larvae and eggs. Reducing pupal numbers in the environment is difficult however, making effective, rapid killing of adults essential. For effective flea control to occur, choice of adulticide, how to effectively treat the environment and management of client expectation all need to be considered.
Failure to consider any of these factors will increase the time required for flea control to be achieved or lead to complete flea control breakdown. Even when all these measures are employed, however flea control may still fail. This can happen for a number of reasons and all of them need to be considered if flea control is to be reestablished.
Drug resistance to worm treatments is an increasingly common phenomenon among intestinal nematodes of livestock and horses, leading to limited treatment options and outbreaks of parasitic disease in the face of routine preventative treatment. Confirmed cases of resistance in cats and dogs worldwide however, are rare with no recorded cases in the UK. There are a number of reasons why resistance has been slow to develop in helminths of cats and dogs. These include large wildlife reservoirs of infection, some worms such as Toxocara having arrested larval stages in tissue which are largely unreached by worming treatments, widespread refugia as opposed to single fields and a wide range of anthelmintics being used, even in relatively small pet populations.
These factors make the risks of resistance developing in domestic pets very low, even if all domestic pets were routinely treated monthly. The reality in the UK is far from this dosing frequency however, with the treatment frequencies in the UK recently being recorded as only 3.1 treatments per year for both cats and dogs. Resistance developing would lead to significant increases in zoonotic exposure and both pet and human morbidity. Current dosing regimes in the UK however, are below the minimum of 4 times a year for Toxocara recommended by ESCCAP, so the zoonotic risk this represents is currently higher than the minimal risk of resistance developing. Resistance is also not reduced by not treating uninfected pets. Allowing Toxocara and Echinococcus life stages into the environment to act as refugia to reduce selection pressure carries zoonotic risk and is therefore hard to justify. Efforts should therefore currently be focused on increasing deworming frequencies, particularly in high risk groups such as puppies, kittens, hunting pets and those fed unprocessed raw diets.
The threat of resistance however, should not be taken lightly and can be minimised by accurate dosing and administration advice, as well as risk assessment for clients which bring value to parasite control programs.
Chronic ehrlichiosis may develop months or years after infection with Ehrlichia canis if acute infections are not diagnosed and treated properly or prevented. The chronic form of the disease often leads to fatal complications including thrombocytopenia, immune suppression, chronic anaemia, coagulopathies and ascites. The prognosis at this stage is grave. Treatment with doxycycline at 10mg/kg once daily for a minimum of 3 weeks can be attempted alongside supportive treatment for coagulopathies, thrombocytopenia and treatment for secondary infections as long as owners understand the potentially poor prognosis.
Puppies and kittens provide the largest source of environmental contamination with Toxocara eggs with zoonotic potential. Treatment of puppies should start at two weeks of age, repeated at 2 weekly intervals until 2 weeks post weaning and then monthly until 6 months old. This is to eliminate T.canis egg shedding from trans-placental and trans-mammary infection and significant populations establishing in the intestine. Kittens should be treated in the same way but the first treatment can be given at 3 weeks old as there is no trans-placental transmission. Bitches and Queens should be treated at the same time as puppies and kittens to kill worms arising from autoinfection during this period and prevent egg shedding. Many products are now licensed for use during lactation and pregnancy so the routine worm treatment of bitches and queens can continue from pregnancy. Fenbendazole is the only licensed drug to reduce transplacental and transmammary infection, treating daily form from day 40 of pregnancy until 2 days post partum but even this will not completely eliminate infection of the puppies and kittens and they should still be treated.
Antigen Serology is considered the gold standard test for heartworm in the living canine patient. It is highly specific and in canine patients, also highly sensitive. Sensitivity increases as adult female worm burden increases with the test detecting antigens in uterine secretions. Sensitivity will therefore potentially be lower in cases with low adult worm burdens. If clinical signs combined with a history of foreign travel make heartworm infection a likely differential and antigen serology is negative then Knott’s concentration blood test for circulating microfilariae can be carried out. Numbers of microfilariae may also be low or absent if there are few or no adult female heartworm adults present. Ultrasonography can also be useful in identifying adult worms but the pulmonary artery must be thoroughly investigated.
Treatment protocols vary but the vital components of any protocol are pre treatment with doxycycline and a macrocyclic lactone prior to three adulticide treatments. The variation in protocols tends to occur around the length of these pre treatment periods but all agree that three adulticide treatments are essential to maximise elimination of adult worms. These are given by deep intramuscular injection, two being given 24 hours apart, 30 days after administration of the first injection.
An example of a typical adulticide treatment program is.
The patient should then be tested for microfilariae 30 days post treatment and antigen serology tested 6 months post treatment.
Prednisone has some benefit in reducing the risk of thromboembolic complications if given alongside adulticide treatment where worm burdens are high. If high worm burdens are suspected, then oral prednisolone can be used from the initiation of adulticide treatment at 0.5 mg/kg twice a day for 1 week and 0.5 mg/kg once daily for the second week, followed by 0.5 mg/kg every other day for 2 weeks. These doses are also useful in managing bronchitic signs. There is no evidence that aspirin has any protective effect against thromboembolism in heartworm cases during treatment.
The three most significant factors involved in post adulticide treatment complications are the severity of existing pulmonary vascular disease, the number of worms present and level of exercise. Of these three, over exercise is thought to be the most significant Exercise should therefore be restricted during treatment, starting from day 0 to at least one month after the last adulticide injection. This will reduce the of severe thromboembolism.
Identification and recording of ant ticks removed ticks is important to map their distribution, monitor potential introduction of exotic ticks to the UK, and know which pathogens pets may have been exposed to. Ticks can be sent to the Public Health England Tick Surveillance Scheme for identification. Ticks should be placed in a container with a secure lid and sent in an envelope marked “biological sample” and sent to.
Tick surveillance scheme
Public Health England
Tick surveillance forms and further information can be obtained from https://www.gov.uk/guidance/tick-surveillance-scheme
Lyme disease incidence in the UK human population is increasing year on year with cases rising from 1.64 cases population in 2010 to 2.70 cases per 100,000 in 2017. There is no incidence data for cats and dogs, but we know that they are exposed to ticks infected with Borrelia spp capable of causing Lyme disease. Borrelia spp have been found in 1.8% and 2.37% of ticks attached to cats and dogs respectively. Increased green space, Forestation, wildlife corridors, deer numbers and outdoor recreational activity all increase the risk of tick exposure. Tick activity has also increased with peak activity now lasting from early spring to late Autumn with the potential to come into contact with ticks at any time of year. The overall risk of exposure of cats and dogs to infected ticks is therefore increasing.