However, active dogs and those with heavier infections may show the classic signs of heartworm disease.

However heavy infection may cause intestinal obstruction, diarrhea and weight loss.

In heavy infections, only examining cartilage microscopically may be needed to find spores.

Each smaller section contains several juvenile worms, and dogs may eat millions of them, resulting in very heavy infections.

Blood cultures may be positive in heavy infections.

In heavy infection young leaves are even deformed.

The principal clinical signs in heavy infections are rapid weight loss and diarrhoea.

However, in the rare heavy infection, hyperpnoea may occur.

Successive progeny from the same dam often shown heavy infections.

He added, pointing to the youngsters splayed out in six inches of water, "That's why the boys have the heavy infections.