Managing Canine Demodicosis

Presenter – Anthony Chadwick BVSc Cert VD, MRCVS, dermatology referral consultant in the north west and founder of ‘The Webinar Vet’.

My first thought when being faced with a dog suffering from demodicosis is one of concern. Managing these cases can be difficult – and this doesn’t take into account the challenges we face in getting a diagnosis in the first place. As far as I’m concerned any update on Canine Demodicosis is always welcome and I was delighted to hear that this was the subject of choice for last week’s veterinary webinar being led by ‘The webinar vets’ very own Anthony Chadwick, refreshed from his summer holidays in beautiful Croatia.

Demodicosis is split into two categories, localised and generalised. Those young puppies we see with the odd patch of non-pruritic alopecia who skin scrape positive for demodex will be suffering from localised demodicosis.  When discussing these cases further Anthony went on to say something that was music to my ears. That there really is no need to shampoo these dogs in  chemicals such as amitraz.  All we need to do is ensure they have good nutrition and are up-to-date with flea and worm treatments. This is often adequate intervention and most affected dogs will grow out of their problem within a few months.

Generalised demodicosis can be more challenging, often needing treatment over a long period. Anthony believes he has a 90% cure rate with juvenile onset demodicosis but they will often need to be treated for at least 2-3 months. He also recommends not breeding from these animals as they may have an inherited autosomal recessive gene which is thought  to predispose dogs to demodicosis.

Immunosuppression is often linked to older dogs suffering from generalised demodicosis and is often caused by other underling disease. Conditions such as hypothyroidism and cushings disease should always be ruled out. However, Anthony stated there will inevitably be some cases where an underlying cause is not found. In these cases Anthony always warns the owner that something may become evident over the next few months. Unfortunately, in Anthony’s experience, many of these dogs go on to develop neoplasia several months down the line.

There are many treatments available for demodicosis and Anthony cited his preferences whilst still managing to comply with the cascade. Moxidectin will often make affected dogs look better but most are not microscopically cured. However using this treatment on a weekly basis may be more successful. Anthony generally starts dogs on four weekly Moxidectin treatments but if mites are still present after this period, the use of something more potent is necessary. Currently his treatment of choice is milbemycin at a dose of 1-2mg/kg daily until remission and then for a further 4-8 weeks. Milbemax for cats can be used as there is such a negligible dose of praziquantel within the tablets. It may also be a wise choice for ivermectin-sensitive breeds as long as the starting dose is low and is slowly increased to ensure no side effects are seen.

Yet again this veterinary webinar has filled me with confidence when it comes to diagnosing and managing canine demodicosis, and as always there is so much more I could have written within this blog.  Further advice included the importance of hair plucks and biopsies for diagnosing this frustrating disease, and the usefulness of other treatments.. Logging into this veterinary webinar is a must for any general practitioner and thanks again to Anthony for providing such an interesting and informative discussion – it’s great to have you back.

The Stethoscope (MRCVS)