Worming should be performed every 2 weeks until 12 weeks old, then monthly until 6 months old and then every 3 months for life. This is in both dogs and cats.
Flea burdens are at their highest in warmer months, but flea prevention should continue all year round to prevent infestations. Some animals are very sensitive to flea bites, thus flea prevention reduces the occurrence of allergies. Fleas can also transmit tapeworms, at any time of year, which can cause other issues.