Guide to Preventing Parasites.pdf - Royal Canin Canada

infected animal’s health. Since infection pressure is low in our region, very few animals –
in absolute value – receiving preventive treatment will be infected.
According to postal surveys carried out in Canada in the past, the number of animals
infected despite preventive treatments (including those cases where people forgot to
medicate their animals for several months) was about 1 dog in 10,000. By way of
comparison, and according to the surveys, the prevalence of heartworm disease in
unprotected dogs was approximately 1 or 2 cases per 1,000. This would work out to a low
percentage of 0.1 to 0.2% of dogs that could be infected due to incomplete drug efficacy.
Therefore, there really is no deed to change our current practice with regard to our
regions and to our animals, if they never venture into highly enzootic areas.
Greater emphasis should be placed on the annual screening test in certain animals. The
following groups, which are considered to be at greater risk, might serve as a guide to
making this decision:
Dogs that travel to enzootic areas, such as the eastern half of the United States or
any coastal area anywhere in the world.
Dogs that live in an area of Canada considered enzootic because one or more
cases were detected there in previous years.
Dogs that live in rural areas.
Dogs that spend a lot of time outdoors.
Before initiating a second season of prophylaxis.
If there is reason to believe that one or more doses have been missed.
What type of test should be used? Our objective in using a diagnostic test is to identify
infected animals in order to treat them and to prevent transmission of the infection to
other animals. It is important to treat animals with health problems or microfilaremia.
Occultly infected animals might be identified by antigen testing but will, in all likelihood,
be treated like noninfected animals. The number of cases of occult infections in an area of
very low endemicity, such as in Canada, will always be extremely low. That equals to
about one-fourth the number of microfilaremic cases, or 0.02% of all dogs. Therefore,
blood concentration techniques make it possible to identify animals that are transmitting
the infection, and animals manifesting clinical signs will undergo a battery of tests in any
event. In conclusion, blood concentration techniques enable us to achieve our objectives
just as well as antigen tests. However, this applies only to areas where the prevalence is
extremely low, which is the case with most areas in Canada.
Should one continue to take preventive measures? The postal survey enabled us to
closely monitor the situation in Canada, despite the problems associated with the survey.
We have now abandoned this approach and are using instead web-based voluntary
reporting. This very practical tool worked well in 2004 and 2005, but it is obvious, with
39