There are several ways of using parasiticides: as impregnated collars, spot-ons, shampoos and sprays, and as oral formulations.

Impregnated collars – the active ingredients are slowly and continuously released in low concentrations, spreading from the site of contact over the entire skin surface. Impregnated collars have an effect that lasts several months.

Spot-on solutions – are applied to the skin on one to four spots on the back of the neck of the animal. The product distributes across the skin and hair of the animal over the following days. They are convenient and easy to use but their effect can be reduced by bathing and swimming.

Shampoos and sprays – products that are available OTC are used for one-off treatment and have no lasting effect.

Oral formulations – flea and tick and worming products are available OTC as tablets. A few roundworm products are available as granules, paste, syrup and suspension.

What if flea products don’t seem to work?

A flea infestation can be difficult to control. Many people assume the products do not work due to resistance of fleas to the product. However, there is no strong evidence of a resistance problem.

Lack of effect is most likely to be due to incorrect use of the product and a lack of understanding of the need to break the flea reproduction cycle (i.e. the need to treat the environment).

It takes time and perseverance and possibly several treatments to eliminate an established flea infestation. If a customer complains that a product is not working, it is worth checking the following:

• Was the product used correctly, according to the instructions?
• Has the animal been shampooed or does it swim?
• Has the environment been cleaned? (There can be areas that are not so obvious, such as garden sheds)
• Were all animals in the house treated?

Reflection exercise

With your pharmacist, discuss the role of pharmacy team in giving advice on animal medicines.