The warning signs

Allergies, Diseases, Itching, Lesions, Infections.

Unfortunately, fleas are so small they are hardly observed...
If a cat or dog scratches itself more than usual, it may well be infested with fleas. As fleas as so tiny they are hardly visible, so by the time you notice your cat or dog scratching, it is probably already infested. Adult fleas measure between 1.5 and 4.5 millimetres, but it is important to remember that 95% of the flea population are still in the egg, larva and pupa stages and are not visible at all!

When ticks can be seen, that means they already engorged from pet’s blood.
Ticks are bigger than fleas so are easier to detect. There are also more warning signs. Check for ticks if your pet seems to have a fever, has lost its appetite, is in pain or showing signs of lameness.