Page 44 - VetCPD Jnl Volume 7, Issue 4

VETcpd - Parasitology 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 be very fluid.
Control through reduction of exposure to intermediate host is difficult due
to the ubiquitous nature of gastropod intermediate hosts. Practical steps to limit exposure include keeping dog toys indoors, regular cleaning of outdoor water dishes and not walking dogs in wet conditions when slugs are likely
to be active. It is likely this and similar preventative measures will reduce but not eliminate the risk of exposure. Picking up of dog faeces is an important component of parasite control and may have local impact, especially as coprophagic
Figure 2: Typical taeniid egg
Pockets of endemic foci remain in the
UK despite extensive attempts at control. Herefordshire, Mid Wales and Western isles of Scotland are known to be endemic foci but surveys of abattoirs and hunting dogs in Britain suggest there are endemic foci in other parts of the country.The location of these is currently uncertain.
The eggs passed in the faeces are immediately infective, so good hand hygiene forms an important part of control.This is especially important for people whose jobs potentially bring them into increased contact with dog faeces such as veterinary professionals, farmers and kennel workers. Not allowing dogs access to carcasses and offal will also break transmission but this is not always practical in remote areas.The picking
slugs may be accidentally ingested by coprophagic dogs.The large fox reservoir of infection means that this is unlikely however, to be an adequate control measure on its own.
up and disposal of dog faeces is also important to limit intermediate host exposure. Feeding dogs cooked diets or raw diets where offal has been frozen to -18 degrees Celsius for at least seven days will also help to avoid transmission to dogs through the ingestion of raw offal.
Subscrib
ial. Echinococcus ers
While these measures are likely to have
Figure 3: Unenbryonated toxocara egg
lungs central nervous system, bone and
some impact in reducing risk of canine
E.granulosus is a cause of serious zoonotic disease and so routine preventative treatment in dogs at risk of exposure in
exposure to infection and are worth
heart. Canids, primarily domestic dogs,
employing, some exposure in dogs at
are infected by ingestion of cysts through
high risk is still likely to occur. Use
scavenging or feeding of offal.
of a licensed monthly moxidectin or milbemycin oxime product will minimise the risk of disease in these dogs. Dogs
may be at high risk due to lifestyle.This includes dogs that deliberately eat slugs and snails and those that may accidentally ingest them though consumption of grass and coprophagia. Some dogs will be at risk due to geographic location. In areas known to be endemic foci then monthly preventative treatment should be seen as routine, especially prior to surgery. In areas where endemic status is less certain then testing of dogs prior to surgery and those with relevant clinical signs will rapidly build up a picture of whether A.vasorum is endemic in an area and whether routine chemoprophylaxis for dogs is required. This data accumulation is vital if risk based advice is going to be given.
Echinococcus granulosus
Echinococcus granulosus, the cause of
cystic echinococcosis (hydatid disease)
in people, is a tapeworm of dogs.Adult tapeworms are typically 5-6mm long with hydatid cysts then being found in intermediate hosts including ruminants, equines, pigs and man.These cysts lead
to offal condemnation in livestock but
in the human host can lead to serious pathology with cysts forming in the liver,
Page 40 - VETcpd - Vol 7 - Issue 4
Infection is well tolerated in domestic dogs and clinical signs rarely seen.
emic areas i
s essent
end
spp. adult tapeworms are exquisitely
Onlysensitive to praziquantel and this remains Therefore, routine screening of dogs for the treatment of choice in cats and dogs.
the parasite is desirable given its high A dose of 5mg per kg orally in dogs is zoonotic potential. The Gold standard for sufficient to eliminate infection.The pre
diagnosis in canids remains examination patent period (time from initial exposure of the intestines at necropsy for adult of infection to ova being passed) is 6-8
E.granulosus tapeworms by sieving weeks so treatment with praziquantel
intestinal contents and scraping of the
intestinal wall (Deplazes & Eckert, 1996). known endemic areas to reduce zoonotic This is a highly sensitive and specific risk.Although the pre patent period technique in experienced hands but is
expensive, can only be carried out at
post mortem and is impractical to carry
out in practice due the health and safety
implications. Proglottids are almost never
seen in the faeces and ova detection in
faeces by faecal flotation is insensitive.
Even if eggs are seen, the eggs are typically
taeniid in appearance and cannot be
differentiated visibly from Taenia spp. eggs
(Figure 2).These difficulties in diagnosis
have led to the development of copro
antigen PCR testing to increase sensitivity.
These are now commercially available but
only detect infection once it is patent and
human exposure to eggs in the faeces has
already occurred.
This makes the implementation of routine control measures important in endemic areas. It also makes monitoring spread of the parasite and assessment of risk vital.
In contrast to A.vasorum and E.granulosus, T.canis and T.cati roundworms are ubiquitous, with almost all puppies, kittens and many hunting cats being infected prior to anthelmintic treatment.The prevalence of patent infection in untreated adult cats and dogs is highly variable
at least this frequently is essential in
means that treatment every six weeks should block shedding of ova, monthly treatment is often adopted to fit in with monthly flea and roundworm treatments and therefore increase compliance. Outside of known endemic areas, dogs whose lifestyle puts them at high risk of infection should also be routinely treated. This includes those with access to raw offal or livestock carcasses.
Toxocara canis and cati
with a recent UK study having found 5% of dogs and 26% of cats to be shedding