You itch what you eat

It is often said you are what you eat, and this is also true for our four legged friends. Unfortunately, the itchy problem of food allergies can make a pet and his guardian alike go bonkers, the pet scratching for relief and the owner going loopy searching through bags of food looking for a magic cure.  This week I am addressing food allergy, an immune reaction to food that is seen in both dogs and cats.

Diet has long been recognized as a cause of hypersensitivity-like skin reactions in dogs and cats.  Allergy to food is the third-most common hypersensitivity skin disease after flea bites and atopy (inhalant allergy).  There are many breeds of dogs that may be at higher risk for development of food allergies. Studies show that males and females have the same rate of food allergies, and age at presentation can vary from young to old.

Almost every pet who has a food allergy itches and scratches like crazy. The itching is relentless. Often scratching is directed at their own feet or ears. Common secondary sores include red rings called “collarettes” as well as traumatic red areas called “hot spots”.  In cats, food allergy often presents as itching around the head and face.

Other diseases that cause similar clinical signs in dogs and cats include atopic dermatitis, or allergy to weeds, grasses, trees, pollen, and household allergens such as dust and dander. Flea bite dermatitis, is another cause of severe allergy in dogs and cats that presents like food allergies.  These very common and nasty symptoms occur after a flea bites a pet thus inoculating with a tiny amount of flea saliva while taking a blood meal from your pet.  Days to weeks later many pooches will suffer delayed hypersensitivity reactions and break out with sores and rashes that make them look worse than a Tenderloin crack user.

Many pets with food allergies have a concurrent component of one or more of these, so we should address the symptoms and also diagnose the underlying disease as well.  Antibiotics, steroids, baths, and dips can help treat secondary infections, but the true diagnosis of a food allergy is still an “elimination” diet.

According to most veterinary doctors, including specialists and referral dermatologists, the ideal way to diagnoses a food allergy is to feed a hydrolyzed protein or hypoallergenic diet.

It is generally believed that the protein source in a diet is the molecule responsible for your pet’s system’s reaction.  This reaction is what causes a negative immune response and subsequent itching and sores.  Purina’s HA and Hill’s ZD diets are made with a process that cleaves the proteins so they are too small to be noticed by the pet’s immune system.  Since the immune system cannot recognize them as irritating or foreign, the allergic process slows down or stops.

Commercially available elimination diets include Purina LA, Iams, and KO. (Kangaroo and Oats).  These novel sources of proteins represent a fresh start for the pet and allow the immune system to take a break from the barrage or irritating proteins.

The rewards can be bountiful — better skin in just eight weeks, without creams or gimmicks.  In my practice I let clients know their pet needs to eat the prescribed food only, without as much as a speck of anything else for a minimum of eight weeks.  This means tough love.  No scraps, none of their previous food, milk bones or anything except the prescribed diet.  Owners need to be aware that even a small amount of a hot dog or other morsel can set the pet back to square one.

Clinical signs in the waylaid pooch often begin to improve in as early as seven days. If improvement is obvious, in the absence of other remedies (such as antibiotics, baths, dips) your pet should now be challenged with her regular diet to confirm the food allergy diagnosis. This means you feed Fido his old food to see if his old clinical signs return.  I know this may seem mean but it is the only way to truly confirm the problem at hand.  Recurrence of clinical signs usually begins within one week but may take as long as two weeks.

At that point the pet is given the elimination diet again and the pet owner may then elect to challenge with suspected allergens, each one being given one to two weeks at a time.  The most common allergens are beef, chicken, milk, eggs, corn, wheat, and soy.  In cats, fish and milk products usually are the offenders. Allergies to more than two allergens are uncommon.  Once the offending allergens are identified, you may feed your dog commercially prepared dog food that do not contain this specific allergens.

Because there are many variables and requirements for success and the stars and planets seem to have to line up precisely, success is measured over weeks and months, not days.  With this information you and your veterinarian can make your pet more comfortable and less itchy, even though it may take a little time and patience, especially by your dog, to succeed.