Psoriasis in dogs?

Dermatitis .. yes, psoriasis? no, not as far as I know.  Psoriasis is an auto-immune thing and the flakey patches are silvery looking not scabby.  Dermatitis is often just a general term for unexplained sore skin.

Food allergy is a really easy kind of cop out diagnosis sometimes -- but the *ONLY* way to truly diagnose a food allergy is with a true elmination diet.  (which doesn't include commercial food)  You really can't blood test for a food allergy.  Dr. Jean Dodds is developing a new saliva test for food intolerances but it's not available yet.

 The best luck I've had with dog allergies overall is both with TCVM (Traditional Chinese Veterinary Medicine) and homeopathy.  The herbs used in TCVM can help itching SO much, and so can homeopathy.

I'm not talking about leaving your vet -- I'm talking about TCVM as complimentary therapy.  But it's been the best answer for my allergy dogs (and I've had many of them - Billy was major!)

 I'm sorry that Chico is so itchy. I may have answered some of your posts before, since I also have an allergy dog. Here's some basic things you can do, and forgive me if I suggested them to you before;

    You need to use a shampoo to help his skin. Has the vet determined if he has a bacterial or yeast infection? There are shampoos for that and the vet should have some good ones at the clinic. If there is no infection, than a good allergy shampoo should help. From personal experience, I can recommend Allermyl, which is made by Virbac;

Amazon.com: Allermyl Shampoo for Cats & Dogs 8 Oz Bottle: Kitchen & Dining

  You may need to use it a few times a week until his skin feels better. Once a week is recommended for maintenance.

  If you follow the shampoo with ResiCORT leave on lotion, it will relieve the itching longer;

 Amazon.com: ResiCORT Leave-On Conditioner (16oz): Home & Garden

   Do you give him antihistamines and  fish oil? Research shows that when you give them together, it helps relieve the itching and can be as effective as steroids;

Allergies & Atopy in Dogs;

"Studies show that when omega-3 fatty acids are used in conjunction with other treatments, such as antihistamines, the use of steroids can often be decreased or discontinued. Be sure to use an omega-3 fatty acid supplement derived from fish oil. Other types of fatty acids (such as omega-6 fatty acids) can actually make some allergies worse."

  Jessie is on allergen immunotherapy, which is the same treatment used in humans for allergies. It has helped her a lot but I still have to give her antihistamines and an occasional bath in mid July through August because the weed pollen count is so high. Before starting immunotherapy, she used to be very itchy year round in spite of baths, fish oil, and antihistamines. You may want to consider this for Chico. Here's a link to the company that makes Jessie's serum so you can learn more about it;

  Bio-Medical Services - Home

  I'm so sorry you're going through this. It can be so frustrating trying to find something that works for your dog; good luck.

The mssing hair on the ears combined with the other symptoms make me think of sarcoptic mange. It is treatable but if Chico has it other animals in your house might catch it and all should be treated.

See the following for info  :

http://www.marvistavet.com/html/body_sarcoptic_mange.html

http://www.merckvetmanual.com/mvm/index.jsp?cfile=htm/bc/72005.htm

 The way to diagnose is thru skin scapings but because the particular areas scraped might or might not have a high level of the mites at a given time, it is easily missed.  A vet vist  seems to be in order. I suspect more than food or environmental allergies.