Expert: Dr. Louis N. Gotthelf - 5/14/2008

Question
QUESTION: My 11 yr old beagle/terrier has demodex.  While we thought she had problems with the thryroid, she does not.  Is it possible that an undetected ear infection has compromised her immune system? I don't wish to think that something else may be seriously wrong with her (cancer).  Other then the demodex she is completely normal

ANSWER: In an old dog with demodex, there is something wrong with the immune system.  I have seen demodex in an ear, but it is not caused by an ear infection.

---------- FOLLOW-UP ----------

QUESTION: while I know that hypothyroidism and cancer are underlying causes of demodicosis, what would be some other things that could compromise the immune system?  Also, the dog is being treated with mitaban dips, how soon should we typically see improvement with her skin?

Answer
There are many immunosuppressive diseases including cancers, diabetes, autoimune diseases like pemphigus and discoid lupus, cushing's disease, and some chronic infections, like dental diseae and chronic urinary tract infections that depress the immune system.

Mitaban dips contain amitraz, which is ery good at lkilling the mites. THey live deep in the oilglands that surround the hair follicles, so it can take some time for the mites to die and for the hair follicle to start producing hair.  Also, many of thse dogs have skin infections that need to be treated c=oncurrently.