Naturally cautious about worming

I am very confused about whether I should worm my dogs or not! I worked as a vet nurse for ten years during which I didn't question the marketing material for the worming tablets we used to sell. As a result I wormed my dogs every three months. However, since leaving nursing and becoming a self-employed dog-walker, I have become very interested in caring for my dogs in a more 'natural' way. I can't help but worry they will come to harm if I do not worm them though! My dogs are both small-ish (about 10kg) rescue mongrel bitches, age 3 and 11.
They are fed NatureDiet with the following supplements: Dorwest Herbs (DH) garlic tablets. DH Keeper's Mix and diatomaceous earth. Both have ingredient intolerances / allergies. My older dog has recently started treatment for Cushing's Disease (60mg 'Vetoryl' daily). I also have a six year old son, who I do not want to come to any harm either! Any advice would be much appreciated...

Many Thanks,
Claire
PS Given the opportunity (ie when I look away for a split second!), both of my dogs love to eat dead 'things' or snack on other animal's poo - or roll in it... Sorry - a revolting PS I know! (dog-owning isn't for the squeamish is it?)
Best Wishes, Claire

I can quite understand where you are coming from, having been working as a veterinary surgeon in practice for 20 years come July! Advice has varied over the years, as have the worming products which now include spot-on as well as various oral formulations.
A simple answer is: Risk Assessment, the approach advised by BSAVA (British Small Animal Veterinary Association). The choice of wormer, its spectrum of activity and the frequency of treatment are tailored to the individual dog and owner, based upon Risk Assessment.
Routine worming is aimed primarily at Toxocara canis, although lungworm is becoming an increasing concern (contracted by eating infected slugs and snails). Risk assessment will include the kind of environment where you live and your dogs’ life style. Where are they habitually walked (public park or isolated wood, for example)? Do they scavenge in the garden? Whilst out on a walk?
The concerns are not only for the health of our dogs but also the risk to humans of contracting toxocariasis. A commonly quoted statistic is that someone goes blind from the effects of migrating Toxocara larvae every week in the UK.
As well as clearing up promptly after your dogs in the garden, it would certainly help if everyone picked up after their dogs whilst out on walks! Having a six-year-old son would tend to push the results of Risk Assessment towards worming as often as recommended by the manufacturers of the product used.
An alternative approach might be to have your dogs’ faeces examined under a microscope. That leads me to finish with another question: How often?
Alison Logan, Vet

Toxocarasis is something that most people associate with dog poo, but it is equally possible to contract it from cat and fox poo, too. No one worms foxes and cats that go outside and kill are very hard to keep worm free - but the dog seems to be much in need of Max Clifford's services as it is always dog poo that is linked in the media to people going blind.
I am told that to contract Toxocariasis you have to ingest poo from an egg-shedding host and it must not be fresh and there needs to be other 'ideal' environmental factors in play to make it dangerous. It would seem that the dangerous situation is while gardening or if kids play in uncovered sand pits - that would seem to be the most likely way to swallow the horrid stuff - by getting it under finger nails and not thoroughly washing hands. As most dogs have not yet learned how to bury their poos, I think the chance of eating affected dog poo by mistake is much less likely than cat poo.
If poo is picked up promptly and disposed of it is of no risk to anyone.
I've found a paper from Japan that suggests coackroaches can even be a vector, too. I wonder what the comparative figures are for Toxocariasis in countries that don't have very many pets?
There are many urban myths with the Toxocariasis figures, too and some years ago vet Bruce Fogle decided to approach all the hospital in Britain to find out exactly how many people have gone blind due to this disease. It certainly wasn't one a week, in fact it was difficult to find any cases of people going blind from this cause. Obviously even one case is one too many.
A long time ago a very damaging TV documentary on dog poo confused the statistic for cases of Toxoplasmosis with Toxacariasis and the figures have sadly been oft repeated since that time confusing everyone.
Toxoplasmosis is indeed very serious, particularly to pregnant women who can lose their babies - but the risk areas are there are cat litter trays and undercooked meat.
Beverley Cuddy, Editor

I would just like to clarify a few points from my initial reply. It is always hard to know just how much detail to give.
It takes a few weeks from the time that a dog swallows a viable Toxocara canis roundworm egg to himself passing viable eggs (the pre-patent period). The reason for picking up dog poo as soon as it is deposited is that any roundworm eggs present are not immediately infective to other animals. There has to be a period of development in the environment which is primarily temperature-dependent and therefore shorter in the summer (as little as two weeks) than in the winter (several months). Additionally, the eggs can survive in the environment for two years and more.
I have just had to bath my dog after she rolled in fox muck whilst out on our walk. As I have said before, she also eats stale dog poo, and on this basis I do worm her regularly, but not every month. Cat poo is another potential source, and especially from feral cats who will not be treated for roundworms. This is why, if you have concerns about routine worming, then having your dogs’ poo regularly examined would be another way to help you decide when they need treatment.
Alison Logan, vet

Toxocariasis
According to the Health Protection Agency (which used to be PHLS) in both 2007 and 2008 only one positive case was recorded in each year. This shows a continuation of the trend starting in the 1980's. In those days you would get about 40 or so positive reports per year with a proportion, perhaps about a dozen, being associated with ocular conditions. However a positive blood test may be coincidental and not specifically diagnostic.
Numbers being reported declined steadily through the 90's and I continued to monitor the figures as best I could after I retired from PHLS and did locum work. By the time I finally retired in 2005 reports were few and far between. There was an anti-dog pressure group of a woman working from her home - I forget the name - who put out supposed figures, starting at 50 cases per year and within a few months it was 50 cases of blindness, then 100, then 200, then 400! If this was so then our laboratory should have seen about a dozen cases per year. On checking, we submitted over a five year period ninety odd specimens- only one was a low titre positive which was almost certainly irrelevant!
While I am not up to date with the scientific literature, I doubt if anything has changed since I wrote about toxocara (and toxoplasma) in the Kennel Gazette in the early 90's plus other reviews.
On worming, I still think the important time is early puppyhood, starting at two weeks then every two weeks till about two months then decreasing till about 6m by which time the now mature immune system should be keeping them dormant.
I use Panacur but am not up on the others but I do wish they were available under generic names rather than trade products - the old paracetamol/Panadol question!
Archie Bryden

See the main blog for an in-depth article on the real risks of Toxocariasis and Toxoplamosis.