One of our readers writes:
I have 2 Chihuahuas, one weighs 10 pounds and the other weighs 15 pounds. They both have the same symptoms: scratching, biting and pulling out hair. My vet gave them both a long-acting cortisone injection June 1st, and the symptoms stopped. On July 2 they started again. I waited until July 11 and took them back for another dose. The reielf only lasted about 1 week this time. I don't want them to have to take the shot every month. What is the alternative to Depo? We have looked and found no fleas, mites etc, just allergies. Thank you!
I always feel that the best person to advise you is the veterinarian who is seeing your dog. I can only give some general information.
It is very important to rule out other causes of itching, such as the mites and fleas that you mentioned. One also considers skin infections with bacteria or yeast. If infestations or infections are present, they may actually be causing the bulk of the itching. Taking care of those factors can really reduce the need for specific allergy treatment (or make it more effective).
This dog has allergies… and mange mites, and yeast infections, and staph bacterial infections, and a congenital skin disorder. This is the most bizarre case ever, but the point is that you have to look at ALL the problems, not just the allergy.
It is possible to give oral forms of cortisone. Some dogs (20% or less) respond to antihistamines. Many dogs benefit from bathing to decontaminate the skin regularly (once or twice weekly). Dogs with itching skin have allergens (pollen, dust, etc.) on their skin, and working its way down through defective skin barriers to trigger the allergy. There are new products that help restore the skin's natural barriers, like Allerderm, or Douxo. Oral fish oil helps some dogs.
With such a rapid recurrence of the itching, especially after the second shot of long-acting cortisone, I would be concerned about a number of possibilities. Your veterinarian has probably already discussed these with you.
If there is a constant, heavy exposure of what you're allergic to, then the medicine doesn't work as well. A common example of this would be a flea-allergic dog who was covered with fleas.
Another example is the food-allergic dog. Food allergies are unlikely to be something new in the diet. The specialists tell us that it generally takes months for the dog to become sensitized to a food substance. Therefore, it is something he has been eating for some time.
Medicines rarely help the food-allergic dog. Again, they have such a constant intimate contact with the allergen — they are EATING IT. It's inside them from one end to the other. It is necessary to do a dietary elimination trial. The dog is fed NOTHING but a hypo-allergenic diet for four to 12 weeks. This might be a novel ingredient diet (like kangaroo and oats, or rabbit and green pea), or it might be a hydrolyzed antigen diet (like Purina HA or Hill's Z/D), where the protein is broken down into smaller chunks of amino acids.
This has to be done for a long time to allow every bit of the old diet to leave the intestinal tract. Most food-allergic patients will show some improvement by four weeks, but may take much longer to get itch-free (12 to 16 weeks).
Most allergic dogs have multiple things they are allergic to. After the dietary elimination trial, if they are still itching, one could look at allergy testing. I wouldn't go to that expense first, though. The testing doesn't help tell you about food allergy. That takes the dietary elimination trial.
Most itchy dogs can find relief, but many take continuing management, rather than being "cured".