Diet trial: a diagnostic test

"My dog is allergic to....." I hear all kinds of things that people have determined their dog cannot tolerate. And in some cases those may be true allergies. In other instances that may be less than accurate. Perhaps the processing of that food doesn't agree with the dog. Or there are additives that cause some intestinal distress. I think we can all agree that there are some things that perhaps do not agree with us (beans and some green vegetables, for example) but we are not truly allergic to them. This is often true of dogs and cats as well.

The only way to determine if there is a true food allergy is to test for the food allergy. Step one of the food allergy test is to choose a food that is least likely to cause an allergic reaction. This can be tricky if we don't have a good complete history of what the animal has eaten in the past. We do know what the most common food allergens are in dogs and cats. Here they are in order:

Dogs: beef, dairy, wheat, egg, chicken, lamb/mutton, soy

Cats: beef, dairy, fish, lamb, poultry, barley/wheat

Dogs and cats can display some allergies to carbohydrate sources such as corn, rice and potato but these are much less common. However, as I said yesterday animals can develop an allergic reaction to any food protein that it has been exposed to. So just because you have been feeding a Kangaroo/sweet potato diet for your dog's entire life does not mean that it doesn't have a food allergy. It just means that your dog's allergy is much more likely to be to kangaroo than to beef or chicken.

There are three ways to choose a food. The first is to create a home cooked diet. For animals with intestinal signs of food allergy a simple diet of a single whole protein and a single carbohydrate plus some vegetables is probably safe enough for the 2-3 weeks it takes to see an improvement. However, to see improvement in skin itchiness we need to feed the trial diet for at least 2-4 months. If you are doing a home cooked meal it is important that you do this in consultation with your veterinarian and a veterinary nutritionist to be sure the home cooked diet is complete and balanced to meet all your pets needs.

A simpler way to conduct a food trial is to use a commercially prepared food. When choosing a novel protein diet you will need a food that does not contain any of the food allergens that your dog has been previously exposed too. It is very difficult to find a food that meets this criteria with an over the counter diet. You may be feeding your dog or cat small amounts of beef, chicken or soy proteins inadvertently since these are often sources of other vitamins and minerals, even in diets that market themselves as fish or other "novel" protein diets. And it may not be obvious from reading the label whether or not these proteins are found in the diet. So if you really want to know if you dog has a food allergy it is worth using a prescription novel protein diet that guarantees that there is no other protein sources in the food. Down the road it may be possible to switch to an appropriate over the counter diet in consultation with your vet but it is not a great choice when conducting this diagnostic test.

Another commercial option is to use a diet with hydrolyzed protein. These diets have been specially treated to break down all the intact proteins into a small enough size to prevent them interacting with the immune system in the body. Your pet will still get all the benefits of the protein (which the body would be breaking down anyway in the stomach and intestine) without the chance of interactions with the immune system.

Once you have chosen your food option, in consultation with your vet, it is time to start the first stage of the test. And it can be both simple and difficult! Feed your pet. Not too hard, right? True, but while you just have to feed your pet the chosen diet you must be very careful not feed your pet anything else. That includes treats, table scraps, food your kids dropped, eating via hunting, treats from the neighbors, chews such as rawhide and bones and flavored medications.

If your pet is showing primarily intestinal signs of a food allergy you will be looking for at least a 50% improvement in 2 to 3 weeks. This would include no more vomiting, improved stool quality, and stabilization of weight or weight gain (if that is needed). If your dog has Itchy and Scratchy on board it is going to take a bit longer to see improvement. You will need to feed the trial diet for a minimum of 8 weeks and as long as 16 weeks. In that time you will be looking for at least a 50% improvement in level of itching. It is often best to keep a log, rating the amount of itchiness on a daily on a scale of 1 to 10. Remember, many dogs have both environmental allergies and food allergies so the symptoms may not completely resolve.

So you have fed your pet the trial diet and only the trial diet carefully for 8 weeks. You feel pretty sure that your pet is feeling better and is less itchy. So we are done, right? Well, not quite. To truly prove that there is a food allergy present we need to challenge the pet with the previous diet or protein. This means stopping the trial diet and putting them back on their old food. Good news is this part of the test is usually pretty quick. We often will see the problems come back within a week or two on the old food and then we can say with confidence that our diagnostic test has proven the existence of food allergy in this dog. If we choose to expose the dog to individual proteins, one at a time, as opposed to a complete food we may even be able to say specifically what the dog is allergic too.

What if you didn't feel like your pet improved while on the chosen diet? Does that mean your dog or cat does not have food allergies? Maybe. Unfortunately, as with many of our diagnostic tests there are grey areas. There are many reasons why your animal did not respond to the food trial. Perhaps they were getting some other food that you didn't know about (is someone sneaking food under the table?). Perhaps our diet history left out a food and we inadvertently chose a trial diet that contained that protein. Perhaps there is enough similarity between a protein in our chosen trial food and what your dog is allergic too that we are still getting an allergic reaction. If we saw a little improvement but not enough it might be worth considering trying another trial diet. Or it may be more important to pursue other causes of your pets symptoms, perhaps with a referral to a dermatologist for environmental allergy testing.

Itchy scratchy

Meet Itchy and Scratchy. They are the two most common complaints my clients call me about. Now sometimes, this is just a simple case of an ear infection or bug bite or even a nervous animal that chews itself like people chew their nails. But most often Itchy and Scratchy are present because of allergies.

An allergy is an abnormal response of the immune system to a normal, non-harmful, part of the pet's environment. This may be a pollen, bug bite or component of their food. The most common type of allergy that we see in dogs is called atopy. Next most common is flea allergies. Not all flea bites will cause a dog to itch. But a flea allergic pet will have a strong, very uncomfortable reaction to even a single flea bite. And finally, food allergy which is an abnormal reaction to a protein in the animal's food.

Atopy is also identified as environmental or seasonal allergies. Atopy is triggered by substances that the animal comes in contact with through the skin or respiratory tract. In animals, the allergy shows itself with skin reactions. These are the dogs and cats with itchy feet, red itchy armpits and groin areas and chronic ear infections. They may show all of these symptoms or only one. They may become worse at certain times of year as certain pollens increase. They may be worse in one part of the country than another. Atopy typically develops when the animal is about 1 to 3 years old. It would be rare for atopy to show up after about 7 years of age.

Atopy is treated in a couple of different ways. The ideal treatment for atopy would be with hyposensitization, also called "allergy shots". In this treatment the animal is tested to determine the exact things that it is reacting too. These allergens are then made up in a vaccine type injection and the animal is given a series of injections to try and train the immune system to stop overreacting to the allergens. This is the only treatment that really treats the underlying cause of the allergy symptoms. Sometimes this treatment may not be possible or may not work for a particular pet. Other treatment options include suppression of the immune response with drugs. Cyclosporine is one option. This was originally designed as a post-transplant, anti-rejection drug. At lower doses it is safe and can be very effective at controlling the symptoms of atopy. Another treatment option is steroids like prednisone. While steroids are safe enough for short term treatment and can be life-saving in certain disease processes we have to be careful with long term use. Therefore, steroids are not an ideal way to treat atopy unless the symptoms are mild and the steroids can be used infrequently for short periods of time.

Flea allergies are the easiest allergies to treat. Prevention is key here. Keep your pets on regular, year-round flea control and you will never have to worry about them being allergic. If you get behind and your pet gets fleas, removing the fleas and treating the symptoms of the allergy will fix the problem. Flea allergies are usually identified by a very characteristic area of irritation, usually around the base of the tail, extending up the spine and sometimes around the base of the ears. The area will be come very red, possible swollen. Often hair will fall out and the pet may develop secondary bacterial infections leading to more irritation and hair loss. And, of course, if we find fleas on the exam we become even more suspicious of a flea allergy.

And finally, food allergy. Spend any time in a pet store and you are going to hear stories about food allergies and food allergic dogs. However, the actual incidence of food allergy is probably fairly low in the general pet population. And there are a lot of myths out there about food allergies. I hear two most commonly. The first is that their dog is on a "special" diet that doesn't cause allergies. But the truth is any diet can potentially result in an allergic reaction regardless of the components. All it takes is protein from the food, and all food contains protein, to interact with the immune system leading to an abnormal reaction by the immune system and resulting in an itchy dog. The second myth I hear a lot is that their dog has been eating the same food for years so it can't be allergic to it. But it takes multiple exposures, possibly over months to years to lead to an allergic response. So a dog that suddenly develops itchy skin at 7 or more years of age is more likely to have a food allergy than atopy.

And just to complicate matters all of the allergies look pretty much the same: Itchy and Scratchy rear their ugly heads. And sometimes more than one type of allergy is present. It is thought that up to 30% of dogs with atopy also have a food allergy. This is especially true in those itchy dogs that may also show some intestinal symptoms such as soft stools, weight loss or vomiting.

Later this week I want to talk about how to diagnose a food allergy through a diagnostic test called an elimination diet. This is where you get to be the scientist or doctor at home, running a well designed experiment (no risk involved, I promise) on your dogs diet.

And if you have any interest in more myths about food allergies in dogs check out this link.

House calls

I initially started this blog to provide my clients with some information to help them care for their pets. But I think I need to talk a little about what I do and what makes Doorstep, and other house call practices, unique.

The name of my practice is a perfect description of what I do. I come to your door and provide veterinary services in your home. I like to think it is a great melding of modern medicine and old fashioned service and care. So much of what we do daily as vets is essentially outpatient care. And it is based on trained hands, ears, eyes and mind. And I can take those with me wherever I go. I do carry a small amount of equipment with me because sometimes we may need to collect samples to look more thoroughly into your pets internal health with blood, urine or fecal tests. Most of the time pets are so patient and tolerant that we can collect these samples with a minimum of fuss.

People often ask me, why would I want a house call vet? And there are some advantages and disadvantages to the choice. Here are some of the reasons to choose a house call vet.

Stress of the vet visit: Many animals experience a certain level of stress from the trip to the veterinary clinic. And often times this stress is low level and short term and so not a cause for concern. But there are some animals that are profoundly disturbed either by the car ride or the vet clinic itself. These animals may shake uncontrollably, become aggressive or fractious, urinate or defecate on themselves or in the carrier, and continue to show abnormal behavior for hours or even days after the visit. These animals may benefit from having their vet come to them. It eliminates the car ride and the often overwhelming sensory input of the vet clinic. By coming to the home I can take some time to get the pet used to my presence, take frequent breaks during the course of the exam for some relaxation and immediately allow animals to retreat to a safe place as soon as I am done. Now, inevitably there may be a time when we need to have the animal in the hospital so it may be of benefit to work on calming your pets fears about trips to the clinic. But in the meantime we can be sure that your pet stays healthy at home.

Mobility issues: These may be on the part of the pet or the owner. Cat carriers and walkers are not a good combination. Nor are tall jumps into the backs of SUV's for large arthritic dogs. By having me come to you, both you and your pet are relieved of the difficulty of travel to and from the vet hospital.

Our crazy, modern lives: I talk about house call visits being old fashioned care. But in our crazy over-scheduled lives getting to the vet hospital can sometimes seem like just one more thing to add to our day. This can be especially true for families with young or multiple children who are trying to balance not only their own schedules but nap/meal/activity schedules for their children. When the I come to you, you can continue with your day right up until the I arrive. And if you have children, your kids can continue to play in a safe comfortable environment freeing up your attention for the visit. Veterinary clinics are by necessity full of great (and not so great things) for your kids to get into. This can make the trip itself exhausting and distracting for the parents limiting their ability to communicate with the doctor. And distraction on the part of both parent and vet could lead to questions going unanswered and misunderstandings about recommendations and options.

Personal attention: And the final benefit of a house call visit is the unique personal attention that you get from this process. Does your pet have behavior problems that you have been struggling with? By coming to your home, I can get a very good picture of the environment that your pet lives in helping to guide my recommendations. House calls are often a longer interaction as well allowing us to truly discuss all of the issues that you are facing with your pet, not just the specific issue that you called about that day.

Now there are some limitations to house calls as well.

Cost: House calls are time consuming. Not only must I travel to your home and then on to my next appointment, but I always spend much more time with each patient. A typical visit in the clinic lasted about 10-15 minutes. Maybe a little more for sick pets. And in the clinic I could simultaneously juggle multiple patients. Unless you have multiple pets I can only be in one place at a time. This limits the number of patients that I can see in a single day. So there is an additional cost associated with the house call. This is quoted as a house call or travel fee and is in addition to the physical exam fee and any other costs associated with the visit. The cost of this fee will depend on your geographic location.

No specialized equipment: Because I do not own a mobile hospital I do not have the equipment to provide radiographs, anesthesia, surgery or hospitalization. So things like broken bones, swallowed balls, dentistry and seriously ill pets will still need to be sent to a traditional hospital. Some mobile vets do have these specialized vans and can provide surgery, radiographs and dentistry in your driveway. Hospitalization will probably still need to be referred to another hospital.

No emergency: For most mobile vets, including me, it just isn't possible to provide much in the way of emergency care. In most cases, a true emergency is going to require the use of some of that specialized equipment anyway. And I may be too far away to be useful as well. This is especially true in our urban area where emergency hospitals are probably closer and fully equipped. I also need to take some time off to take care of myself and my family. I do still want to know if there is a problem and will work hard to maintain communication w

ith you and the veterinary clinic where you have taken your pet.

Practicing house call medicine is a very different experience than traditional small animal practice. It is much more personal with a stronger bond between myself, my patients and their owners. I love that spending the extra time with my clients allows us to become a team looking out for the best interests of the pets. I love seeing the animals relaxed and happy in their comfortable environments.

Buying your pet's medicine online

Veterinary medicine is expensive. And if you live somewhere with heartworm or have an older pet that needs medication daily for a chronic condition, online purchasing may seem like an ideal way to save a little money. But there are some things you need to watch for when you are comparing online pharmacies.

There have been many instances of online pharmacies selling counterfeit medication or flea preventatives. In some cases the prescriptions have lead to disease and death because the counterfeit medication was actually toxic. In other cases the medication may have been improperly stored or expired making it less effective.

So how can you protect yourself? Start by very carefully researching the online pharmacy you are considering. Check to be sure that the pharmacy is licensed by the state Board of Pharmacy where it operates. If you can't even figure out where the pharmacy is based, that should be a red flag that this pharmacy may not be safe to use. Call the company and asked if there are licensed pharmacists that can answer questions if they arise. Ask your veterinarian if they have ever worked with that pharmacy and if they had any problems or concerns.

Just like the pharmacy down the street, online pharmacies must require a written prescription from your veterinarian before filling a prescription drug request. Many flea and tick products are not prescription (Frontline and Advantage) but arthritis medication is. If the pharmacy offers to fill the prescription for you based on a questionnaire that is another red flag. A questionnaire does not substitute for a patient-client-doctor relationship, regular hands-on physical exams and recommended laboratory work. Giving medications without these safeguards could lead to serious illness.

And finally, some reputable online pharmacies have agreed to go through an accreditation process to ensure that their practices are safe and legal. This program, called Veterinary-Verified Internet Pharmacy Practice Sites (Vet-VIPPS), requires strict quality control, regular inspections, strict confidentiality and internet security. This is still a new program, currently 2 years old, so there are a small number of pharmacies currently accredited but using one of these pharmacies will give you an extra layer of protection to be sure that your pet is getting the correct medications. You can find out more about this accreditation program and pharmacies that are participating here.

Some thoughts on saying goodbye

I didn't realize it had been so long since I had written anything for this blog. It has been a hectic couple of weeks. But since I am home with a cold today it seems like a good time to do a little writing.

I have been seeing a lot of euthanasia's lately and thinking about the toll that this takes on both the owners and the veterinarian helping them. Making a decision to euthanize is such a difficult decision. There is fear that we are making the wrong decision or that we don't have the right to make life and death decisions like this. There is guilt and second guessing and of course over it all the grief of loosing that wonderful partner that our pets become.

They give us so much in their short lifetimes: unconditional love, acceptance, empathy, entertainment, laughs and yes a few headaches and heartaches to provide fullness of experience. We love our dogs right back, often with a simplicity that we struggle to find in our human relationships. And we learn, whether consciously or not, lessons in patience, kindness, and humility. A client of mine recently said that her cat had been sticking around to be sure she learned all she needed to know. I think the final lesson was one in letting go. Perhaps the hardest lesson of all to learn.

I was speaking to a college student this weekend who is considering applying to veterinary school and we briefly touched on this topic. She was concerned that she wouldn't be able to provide this service to her clients. And as a veterinarian it is something that we must all reflect on in our professional lives. When would I be willing to provide this service? Under what circumstances might I refuse? Is there something I can do to help both myself and the owner feel that this is a good decision?

My philosophy has always been that euthanasia can be such a blessing that we can give to our pets. It is a truly courageous and selfless act that we do when we choose euthanasia. We can remove pain, preserve some dignity and spare our beloved pets unnecessary suffering. But in doing so we must give up something unbelievably precious to ourselves. And it is there that we must reach deep into our hearts to find the love our pets have given us and return it, in full measure, by saying good bye. Each euthanasia I participate in is unique and special. I learn something from each of these pets and their loving owners. I too grieve, even if I have only met the pet at this ending of a life, and I try to take a little time to say my own goodbye to each wonderful furry life that I am lucky enough to have contact with.

Thank you for the lessons in love, courage and dignity to all those that have passed and all those who will pass through my life in the future.