Until
a large number of heartworms collect, there are no symptoms.
The larger the number of heartworm infected dogs and other canids not receiving monthly preventatives, the less likely a parasite species is to mutate.
A large number of heartworms can potentially obstruct blood flow to the heart, which could cause your dog to collapse and die unless treatment is initiated quickly to alleviate the clog.
In the final stages of heartworm disease,
a large number of heartworms will sometimes block blood flow to the heart almost completely.
Sometimes
a large number of heartworms will almost completely obstruct blood flow to the heart, leading to caval syndrome.
Dogs with
a large number of heartworm larvae (immature heartworm) may experience a shock - like reaction as the parasites die all at once.
Preventing heartworms is easy with
the large number of heartworm tablets available for monthly dosage.
Once
a large number of heartworms have invaded the heart, blood will stop flowing.
Although less common,
a large number of heartworms can lead to a sudden obstruction of blood flow through the heart and lungs.