In this column veterinarian Dr Liesel van der Merwe provides practical assistance for common problems in companion animals. She is a specialist physician at the Onderstepoort animal teaching hospital and a senior lecturer in the section of small animal medicine. Send your questions to This e-mail address is being protected from spambots. You need JavaScript enabled to view it

Dr Liesel van der Merwe

I have had a lot of enquiries as to ineffective tick and flea control remedies over the past few weeks so I am going to clarify how the different products work. I am also going to name specific products in each category, something I normally try not to do.

I am mainly going to concentrate on tick control due to the importance of tick-transmitted diseases as discussed in last month’s column.

Products are available in different formulations. Powders and shampoos will only work for a few days before the compounds are gone from the dog’s skin. Dips generally last 7-10 days, collars 1-3 months and the topical “spot-on” applications “up to” four weeks.

If a lot of ticks are present in the environment or your dog swims a lot, application may need to be more frequent. The products available can also be broadly classified according to their active ingredients. Frontline-Plus® contains an invertebrate specific insecticide as well as a growth regulator.

Frontline® and Fiprotec® contain only the specific insecticide, which will only affect insects by targeting the nerves. These products are extremely safe and can be used in dogs, cats and young animals.

Revolution® is registered for use in puppies and cats and contains selamectin, which belong to a group of drugs which interfere with and depress invertebrates’ nervous system. These products are effective against ticks, fleas, mites and intestinal worms and are also very safe.

The Ultrum® range, Advantix®, Practic® and Promeris-Duo® spoton and other commercially available “spot-on” treatments contain insecticides such as pyrethroids, organophosphates and amitraz, which may have a harmful effect on mammals if used incorrectly. These medications need to be dosed accurately and, except for Promeris- Duo®, are not safe for use in cats or very young animals.

Preventic® collars contain amitraz, work for three months and are highly effective. All dips (Ectodex®, Bayticol®, Acarins® to name a few) contain a poison and can be overdosed and are harmful to mammals and especially to cats which are extremely sensitive to all insecticides.

Now to answer the question why you still see ticks after applying “anti-tick” products. None of these products is a total repellent as such, so ticks will still climb onto your dogs. The products mentioned will generally kill any ticks it comes into contact with within 24-48 hours. Remember, however, that fresh ticks will always still be present on your dogs, but the same tick should not be there for more than two days.

So why should you bother then? Well, biliary fever is only transmitted by two kinds of ticks and the tick has to bite and “cement” its attachment to your dog before starting to feed. This takes at least 24-48 hours and, as the parasites are transmitted in the saliva of the tick, no infection can take place until they feed.

Amitraz-containing products do not actually kill the tick but cause paralysis, including the mouthparts. Although you may see ticks on the fur, you should not see ticks attached to the dog. Even though these products will not keep your dog totally tick-free, they are almost 95% guaranteed to keep your dog disease-free (biliary and tick bite fever).

The little red ticks are larval stages and although they harbour the parasite, it is thought that they do not actually transmit disease and that only the large adult ticks can transmit disease.

Most products require that the dog is not washed for 3-4 days prior to and post treatment as they rely on skin oils to distribute throughout the skin surface. Excessive washing in-between applications will also decrease efficacy. You cannot apply a topical treatment as part of your dog’s monthly grooming session. So, reassess you program and modify your expectations and let’s see if we can control biliary in our area.