Proceedings of the World Small Animal Veterinary Association Sydney, Australia 2007

Transcription

1 Proceedings of the World Small Animal Veterinary Association Sydney, Australia 2007 Hosted by: Australian Small Animal Veterinary Association (ASAVA) Australian Small Animal Veterinary Association (ASAVA) Australian Small Animal Veterinary Association (ASAVA) Next WSAVA Congress

2 Quick questions: Match your score against the panel Dr. S. Bettenay 1, Dr. M. Burrows 2, Dr. P. Ihrke 3, Dr R. Mueller 4, Dr L. Vogelnest 5 1 Tierdermatologie Oberhaching/Germany, 2 Murdoch University/Western Australia, 3 University of California/Davis/USA, 4 Ludwig Maximilian University Munich/Germany, 5 University of Sydney/Australia In this session, the members of the panel will ask questions of each other and we would like you to contemplate your answer and compare it with that given by the panel members. However, as notes on the questions beforehand would defeat the purpose and as we did not have the space to go into details about elimination diets in the notes about allergy testing, we include here more details about elimination diets and hope you find those details helpful. Tips and Tricks with Elimination Diets To get an owner to perform an elimination diet is hard work in most cases and to keep the compliance up all the way through the weeks needed to make the diagnosis is even more difficult. However as there is no other reliable diagnostic test, the success of the elimination diet is vital as a diagnostic procedure. And I feel completely justified in scheduling recheck visits which serve more of a purpose in checking that the diet is going according to plan than examining the patient. Principle of formulating the diet: The ingredients in all the foods fed in the previous 6 months should be tabulated. A meat source and a carbohydrate source are then selected which are not on that list. It is sometimes helpful to place all the pets in the household on this diet, to prevent thieving and problems of jealousy. 1. Dogs: An elimination diet for canine patients consists of a protein source and a carbohydrate source previously not fed. These are home-cooked and usually fed in a ratio of three parts of the carbohydrates and one part of the protein. The protein part can be increased, but should not fall below 20%. Nothing else is included in the diet. These diets are not balanced and so must not be fed long term. 2. Cats: Cats are obligate carnivores and therefore MUST be fed meat in their diet. In fact they do very well with a meat only diet. For many of our feline patients, I encourage the owners to try to feed meat (raw!) as the ole food source for the 6 weeks, IF that will encourage the cat to eat!! Cats are such fussy eaters that finding a food that they will eat for a longer period of time can be a real challenge. Although most owners are not happy about it, dogs can tolerate not eating for a few days, cats cannot, they run the risk of developing hepatic lipidosis.

3 3. Supplements, Medications: Many of the heart worm preventatives and deworming agents are pork or beef-flavored, so are many of the toys and supplements available for pets!!! These need to be discontinued during the elimination diet. Follow-up The owners should be called in the first week after the diet was agreed upon. The purpose of this call is to firstly check whether they have found a source for the meat (and in the case of a dog, the carbohydrate) and then to check whether they have actually started the diet? During this call, the owners are again reminded not to feed treats. We use the vaccine and reminder scheduler in the practice computer to schedule these calls and revisits. If the owner fails to come back for the scheduled recheck, then a quick call will establish whether it was oversight, whether the diet has never been started or has been broken or whether the dog or cat is now perfect and they see no need to attend! After a period of 6-8 weeks the patient is reevaluated. If the animal is in remission and has been for at least 7 to 10 days, a rechallenge with the previously fed diet is performed. If there is significant improvement, but the animal is still pruritic, the diet can be continued for a little longer to evaluate the full degree of possible improvement on the diet. However, with an owner who is finding this diet difficult, rechallenge may be indicated right away. If there is no improvement after 6-8 weeks or if the symptoms do not reappear within 2 weeks, a food adverse reaction is ruled out. The period of two weeks is set because although most dogs and cats will flare with their pruritus / otitis / whatever their symptoms are within 48 hours or so of the food challenge, some animals take up to two weeks. Performing a rechallenge The rechallenge diet should be all of the foods previously fed, all together for a period of two weeks. The idea is that we want to be able to evaluate quickly whether or not diet plays a role. There are a multitude of reasons why a dog or cat will relapse with their symptoms during a food challenge which have nothing at all to do with the diet. Season s change, flea control measures tend to become less intensive, previous infections which had been treated may relapse. If there is deterioration on the rechallenge, the elimination diet should be restarted instantly. This is easy to organize, monitor and assess if it happens once within 2 weeks of the visit (the one which is made just prior to the rechallange) as the owner is still freshly aware of the plan. If, when the test or elimination diet is re-fed - with no other changes - there is subsequent improvement on the diet, a food adverse reaction is confirmed. Sequential rechallenge: Ideally we then start a sequential rechallenge with individual proteins to identify the offending protein. In our practice, we feed beef, then lamb, then

4 chicken, then pork, then add cheese or milk in the diet for dairy products, add pasta to check the wheat proteins, etc. We feed each protein for approximately one week. You can guestimate the time until deterioration by how quickly the symptoms returned after the rechallenge initially, if there was deterioration within 2 days, it is very likely, that this pattern will be repeated. Once the offending protein is identified, it is avoided in the future. Some owners refuse to perform the sequential rechallenge. In these cases we try several commercial diets containing hydrolyzed or unusual proteins and if no deterioration occurs, we continue to feed these. If the home-cooked diet is chosen as a permanent solution, it needs to be balanced, preferably by a nutritionist, to avoid long term problems. Tips & Tricks There are some tricks to increase our owners' and pets' compliance during this difficult time: Firstly, we always give the owners a range of proteins to try, just in case their pet does not accept the first choice as readily as we like. We commonly offer kangaroo, rabbit, venison, horse, crocodile and combine it with rice, potatoes, sweet potatoes or white beans in dogs. Warm food is more palatable. Gently/briefly warming it in a microwave or just by sitting the plate over a bowl of hot water for a few minutes may increase pet compliance. The careful use of salt and/or adding garlic may increase palatability Treats / snacks / dental health care: To increase owner compliance in situations where regular feeding of table scraps is part of daily family life, we need to provide these owners with treats they can safely feed. Jerky can be produced by drying slices of meat in the oven (low temperature and hours of cooking. The smell is found by many owners to be quite offensive!). Rice cakes consisting only of dried rice are available and can be fed in small quantities just like cookies. Rice is unfortunately found in many commercial dog foods these days. Little pieces of the chosen protein can be fried or grilled twice a week and kept in the refrigerator in a separate treat container. Secondary infections are common and cytology is an important tool to identify organisms involved in clinically suspected infections. Appropriate antimicrobial therapy must be followed up with clinical and microscopic evaluation. Complete resolution of pruritus and lesions in an older dog will raise the possibility of hormonal disease with secondary infections. Many owners raise concerns regarding the concurrent treatment of infection sand conducting an elimination diet. They are quite rightly concerned about how one evaluates such an improvement, when multiple trial therapies and or treatments occur together.

5 We explain that we cannot assess this at the time of improvement, but we can work backwards! A simple client planner chart (for example, see below, idea originated by Dr Michael Shipstone) helps many owners to see clearly what we are doing. There is one extremely important principle in this protocol and that is that one never stops two therapies or trials at the same time and that one preferably allows 2 weeks between making changes. An adverse food reaction is suspected when the pruritus is nonseasonal. It is sometimes poorly responsive to glucocorticoids, however, corticosteroids may be highly effective in other patients. Pruritic bilateral otitis externa and secondary seborrheic skin disease and/or pyoderma are commonly seen in dogs in conjunction with adverse food reactions. Concurrent gastrointestinal disturbances have been reported in a minority of the cases (15%). Otitis externa was the only sign of AFR in 30% of the cases in one study.

6 Elimination Diet? Antibiotics Antihistamine? Cortisone