Sometimes, in spite of your best efforts, you find your dog has picked up a heavy flea burden or a tick. (vetbabble.com)
Some dogs and cats can cope with huge flea burdens with relatively little bother but others will rip their skin apart for one or two fleas. (thearkvet.com)
All forms of flea control should be used if the pet is in danger of serious disease such as flea anemia from the excessive flea burden. (safarivet.com)