Allergies are
a common disease among dogs. Most allergies fall into three common categories:
1) environmental, also called atopy, 2) FAD, flea allergic dermatitis, and 3)
food allergy. Often the pet may have more than one type of allergy. With food
allergies, usually the dog has been on the exact same food for many years
before developing an allergy to it.
Allergies are a disease of the immune system whereby the immune system becomes
oversensitive and creates antibodies to 'normal' environmental or food
molecules.
The common signs of allergies may include one of all of the following symptoms:
recurrent ear infections, hair loss with balding spots, itchy skin - especially
of the belly, face, arm pit and groin regions, red or thickened skin of the
affected areas, dry hair coat, and anal sac problems.
Food allergies can be ruled out before instituting more long term allergy
treatments. Determining whether your pet is allergic to food proteins, a food
trial is required. Food trials are accomplished with a completely
hypoallergenic food for a 12 week course. Note: changing from one commercial type food to another
rarely works because often your pet is allergic to more than one protein in the
food.
Basic Allergy Therapies
Multi Modality Therapy
When dealing with a serious, life affecting disease such as
environmental allergies, we as pet owners and veterinarians, begin to realize
that single medications often fall short of our expectations. The drug either
does not work or seems to work at high levels which may have some additional
side effects. Most commonly we will end up using steroids or other immune
modulating medications. By using multiple medications however, we can end up
using less of each individual medication. Also employing multiple medications
together a synergistic effect may benefits your best friend!
The following is an introduction to some of the options available
for allergies. Always ask your veterinarian prior to using any of these and be
sure to get doses!! For mild to moderate allergies, sometimes these therapies
can be enough. After this section will be some alternative that might need to
be added for the moderate to severe allergies. If you pet has severe allergies,
not forgetting the 'basic therapies' can help the stronger medications work
better and allow you to use less of them - good for your pet; good for your
pocket book!
Omega 3 Fatty Acid Supplementation
There is a lot of information
about Omega Fatty Acids and their benefit to our bodies and our pet's bodies.
However, beware, not all Omega Fatty Acids are the same. Some are essential
(our bodies do not produce them) and others are not. Some decrease inflammation
like Omega 3's (great for allergic pets) and some will promote and worsen
inflammation like Omega 6's (not great for pets). While Omega 6 is also an
essential fatty acid, appropriate levels are already easily available in
commercial foods. There is some debate whether the beneficial effects of Omega
3 lies in an absolute amount delivered to the pet or more due to a ratio of the
Omega 3 to Omega 6. Either way adding in more Omega 3 fatty acids (FISH OILS!)
can be beneficial to your pet's allergy condition; not to mention the other
many beneficial effects of fish oils: lowering cholesterol, increasing kidney
blood flow, decrease joint inflammation and treat arthritis, increased nerve
health, etc...
Will
Omega 3 Fish Oils, solve my dog's allergies? No not by themselves. At
high doses approximately 25% will respond by themselves. * However as
part of a multiple therapy plan, they are extremely helpful.
Unfortunately picking the right
Omega 3 Fish Oils is not always as easy as it seems. It is not FDA regulated
which means that you might not be getting what you think! 3V Free Form Liquid
is made by DVM products who make all of their nutritional supplements in
accordance to FDA specifications. This means that you know what you are
getting. Also the fact that it is 'free form' means that the Omega 3s do not
need to be altered by the body before it is used. The moment they are absorbed,
they can go directly to work. The bottle has a bladder inside which contracts
as you pump it out - so air does not get trapped inside to make it go bad. And
did I mention it was a pump? That is right - no pilling. Just give a pump and
these wonderful Omega 3s get squirted right onto your dog's food. Most dogs love the fish taste and owners love
not having to pill! There are other
brands available and if you know one that you trust - I recommend that you try
it. If you are not sure - consider this one.
*Source:Carlotti D. Long Term Management of Canine Atopic Dermatitis, WSAVA
Proceedings World Small Animal Veterinary Association World Congress,
Vancouver 2001.
CLICK above for more info on Omega 3
Antihistamines for Canine Allergies
Histamine is part of the allergic cascade pathway which ends
up with the clinical signs of inflammation, itching and discomfort.
Antihistamines stop histamine from contributing to these signs of allergies. It
is important to note that allergies include many chemical mediators, cell
interactions and antibody interactions beyond just histamine. This may be a
reason why only about 10% (although another source puts it at 20-30%**) of the allergic dogs will respond alone to antihistamines. However antihistamines remain an important component to many management plans
for allergy pets. There are over the counter antihistamines such as Benadryl (diphenhydramine) and prescription antihistamines such as Atarax (hydroxyzine)
and others. Ask your veterinarian if one of these is right for your pet! Make
sure to ask about dosage and remind your veterinarian about any other
medications that your pet might be taking.
Warning: some benadryl formulations may also contain Tylenol. Do NOT give your pet
Tylenol containing antihistamines.
Here is a list of the most common antihistamines available
for your dog:
First Generation
Antihistamines:
Chlorpheniramine
Diphenhydramine (Benadryl)
Clemastine (Tavist)
Hydroxyzine (Atarax)
Trimeprazine (Temaril)
Doxepin (Sinequan)
Amitryptyline (Elavil)
Second Generation Antihistamines:
Fexofenadine (Allegra)
Astemizole (Hismanal)
Loratadine (Claritin)
Source: "Management of the Allergic Dog" Source:Library, Proceedings, ACVIM 1998Author(s):Leonard D. Jonas DVM,
MS, Dipl.ACVIMDenver, CO
**Source: Carlotti D. Long Term Management of Canine Atopic Dermatitis, WSAVA
Proceedings World Small Animal Veterinary Association World Congress,
Vancouver 2001.
Bathing
Regular use of
hypoallergenic and antimicrobial shampoos can provide some patient relief as
well as help to reduce recurrent infections. It is a common misconception that
you should not bathe your pet too often. This was true a long time ago when
shampoos dried the skin out too much, leading to skin problems such as
increased itching. With the medicated shampoos you can bathe your pet daily if
needed. This can help your pet feel and smell much better.
Many pets with
allergies have problems with a condition called seborrhea which is the abnormal
secretion of a greasy fluid from the sebaceous glands. Sometimes this will
present itself as dandruff, or greasiness or crusting. Antiseborrheic shampoos
can help reduce this greasiness; then following with a conditioner, you can
make sure the skin does not become overly dry.
Anti Itch Spray
There are many over the counter as well as prescription
Anti-Itch Sprays. The over the counter forms include those that help hydrate
the hair through conditioning and those that use steroids. The prescription
sprays will be antibiotics, stronger steroids or combinations thereof. While
topical sprays do get absorbed within the body, they primary concentration will
be within your target organ, the skin. Use of these can help reduce the
frequency and dependence upon oral/systemic antibiotics and steroids.
Antibiotics and Antifungals
As the allergic inflammation worsens in the skin,
opportunistic bacteria and yeast often take advantage and 'set up shop'. Your
veterinarian may ask to perform impression smear cytology - an quick,
non-painful test that can easily be run in just a few minutes. Why do this and
not just refill the antibiotics that you have used before? A couple of reasons,
every once in awhile instead of a bacterial infection, a yeast infection will
occur; or visa versa; or a mixed infection, or a new population and strain of
bacteria, not previously seen. This may alter the type of medication that is
needed. As a general rule, antibiotics can make fungal (yeast) infections worse
and antifungals can make bacterial infections worse. If there is a mixed
infection then both need to be addressed in order for you not to just see 'partial' improvement. If it is a different type of bacteria, then a different
antibiotic, or even a skin culture, might be needed. As the allergies in your
pet become controlled, then hopefully the frequency and use of these
medications will be reduced or even eliminated.
Treat your home!
The use of HEPA filters can help reduce your pet's exposure
(and yours!) to allergens. HEPA filters, by definition, remove at least 99.97%
of airborne particles 0.3 micrometers (μm) in diameter.This includes pollen. Many new vacuum
cleaners employ HEPA filters at an affordable price. There are also air filters
available. Just a note: hardwood and tile floors collect less allergens than
carpets; but don't ask me whether you should remodel your house or not.
Flea Prevention
While this may seem as 'just common sense', it is easy to forget that fleas can complicate allergies. If there are fleas in your area, then using regular flea medication, whether fleas are witnessed or not, can prove highly beneficial. Many pets will have allergies to fleas (FAD - Flea Allergic Dermatitis). If the pet does have a flea allergy, then as little as one flea can make the pet highly itchy and uncomfortable. By preventing fleas, we can eliminate this as a source of discomfort.
Addressing Food Allergies and Endocrine Diseases
When we are addressing the presence of allergies within a pet, it is important to make sure that other disorders are not complicating the clinical signs and reducing quality of life. Many pets who have environmental allergies, also called atopy and the topic of this page, will also have food allergies. Some estimate those pets that have both atopy and food allergies at about 30% of the allergic pets. This means that if your pet has environmental allergies, there is a roughly one in three chance of your pet also having food allergies.
It is also important to make sure that other disorders, such as diseases of the endocrine system are also addressed, if present. Hypothyroidism (low thyroid level), Diabetes Mellitus and Cushing's disease (hyperadrenocorticism) are all common diseases of mild aged to older pets which can lead to skin disease. If an endocrine disorder, such as hypothyroidism is present and not addressed, then the clinical signs of allergies can be made worse and properly getting them under control can be more difficult.
Food Allergy Management
As stated, some estimate that about thirty percent of dogs with atopy (environmental allergies) will have concurrent allergy to food. When pets have food allergies, they are allergic to the protein (typically water soluble glycoproteins which are 10-70kD in size) in the food. Furthermore pets that have food allergies are usually allergic to more than one protein at the same time. Since the ingredient 'chicken' is not just one protein but made up of many different proteins and many pet foods have similar byproducts despite the 'main ingredient'; changing different brands at the store has a high rate of failure. For this reason, either a home cooked diet or a prescription diet is recommended.
What is my pet allergic to? While food allergy is can sometimes straightforward to evaluate for, finding the exact allergen (i.e. chicken) can be difficult. There are several blood tests on the market that evaluate for both environmental and food allergies and will come back with a list of 'what your pet is allergic to'. As a general rule, most veterinary dermatologists do not recommend the use of this test in most pets. Unfortunately the test can have false positives, meaning that the test can indicate allergies that do not exist.
What are the most common food allergens? "The most common allergens identified in spontaneously
food allergic dogs may differ according to geographical location. They
include cow's milk, eggs, meat proteins from beef, and chicken, and
plant proteins from corn, wheat and soybeans" - Frederic P. Gaschen, Dr.med.vet., Dr.habil., DACVIM, DECVIM-CA ("Is it Time to Revisit Adverse Reactions to Food in Dogs and Cats?" ACVIM 2008)
Corn Corn has gotten a lot of hype and for this reason deserves a quick note. It has been implicated as a cheap worthless filler and a frequent cause of allergies. As corn is being more frequently used in pet foods, then we may see an increase in allergies to proteins in corn. However, while some pets may have either allergies or intolerances to corn, its implication may be currently overstated. The following if from Small Animal Clinical Nutrition 4th Ed: "Myth No 1: Corn is a filler, is poorly digested and causes allergies. Fact: Fillers are indredients that serve no nutritional purpose, and
corn does not fit that description. Corn is a nutritionally superior
grain compared with others used in pet foods because it contains a
balance of nutrients not found in other grains. Corn provides a highly
available source of complex carbohydrates and substantial quantities of
linoleic acid, an essential fatty acid important for heathy skin. Corn
also provides essential amino acids and fiber. In a survey of
veterinary dermatologists, corn was not listed among the ingredients
most often suspected to cause food allergies. A review of over 200
confirmed canine cases of food allergy in the veterinary literature
revealed only three were caused by corn. The same number was reported
for rice."
Corn Free Diet Option If you do not want to feed corn to your pet, then there are many pet foods that contain other carbohydrate sources. Remember that every food will have some type of carbohydrate. Many other foods will use rice, wheat, barley or sorghum. It is interesting to note that based on digestibility studies, all of these are less digestible than corn1. While there is a lot of hype regarding the problems of grain, many of the the other substitutes do raise the percentage of carbohydrates higher than corn (for example: sweet potatoes, russet potatoes, chicory root or carrots).
1) Murray SM, Fahey GC, Merchen RN, et al. Evaluation of selected high-starch flours as ingredients in canine foods. J Anim Sci 1999; 77:2180-2186
Russet Potato
How do I test my pet for food allergies? This requires an eight to ten week food trial. The food used should either be a home made diet (recipe available by a veterinary dermatologist) or use a hydrolyzed commercial diet. Hydrolyzed proteins are superior to novel protein diets. Hydrolyzation is a process that reduces the molecular size of the protein. This can be done to a level where the protein can no longer stimulate the immune system and create an allergic response. Novel protein is a protein that the pet has never been exposed to before. The pitfall with novel protein is that some food allergy pets will begin to react to the new protein in a similar manner to the other proteins.
Where do I get hydrolyzed type diets? These are available only from your veterinarian or by a prescription. There are many online sites that can deliver the food to your door as long as you have a written script.
What are the pitfalls of the food trial? The most common problem with food trials is the complete and total elimination of all other food and protein sources. All supplements, treats, and even chewable medications must be stopped. Chewable heartworm preventatives must have an alternate topical or non-chewable medication used instead. Since food allergies is a disease of the immune system that involves the production of antibodies, any exposure to ingested protein other than the hydrolyzed diet can cause the entire trial to fail. If the pet eats a bite of a treat, the trial should be restarted from that day. This makes food trials both difficult and frustrating in many households.
Low Thyroid etc...
Not all dogs that itch have allergies It is important that when we are treating a pet with environmental allergies (atopy), that we 1) actually have atopy and 2) do not also have other problems. It is important that we rule out fungal, parasitic or bacterial infections of the skin that might be a primary underlying cause to the skin problems. Another important category of problems that leads to skin problems is endocrine disease. The endocrine system is the network of glands throughout the body used in maintaining metabolism and generalized cell function. Within this system, we can see certain imbalances which can lead to skin problems. Hypothyroidism is the reduced function of the thyroid gland and is a common culprit of endocrine skin disease. Diabetes Mellitus, a disease of the pancreas and Hyperadrenocorticism (also called Cushing's Disease), a disease of either the adrenal or pituitary glands are also common causes of skin changes in pets. Most of these can be evaluated for on a standard blood test. In some cases, more specific blood tests may be required. If any of these disorders are not addressed and regulated, the skin changes (either from the disease or concurrently with allergies) will remain. Thus we might feel that the 'allergy medications' are failing when in reality it is that there is a separate problem.
The Systemic Medications
Hyposensitization with a Dermatologist
If you are reading this, you have undoubtedly wondered, "Gosh, what is my dog allergic to???!"
Skin testing with a veterinary dermatologist (yes they
exist.) is the best way to answer this question. On rare occasion, you will
find that your pet is allergic to only one or two things that can be removed
from your pet's daily life (i.e. the crab grass in the back yard). Usually your
pet will be allergic to numerous allergens. Once they determine what your pet
is allergic to, they will make an injectable formulation to help hyposensitize,
that is re-train, your pet's immune system. The injections are given on a
regular schedule.
Due to the seasonality of the clinical signs, age of pet,
severity of signs, etc... not all pets are good candidates for this. Consultation
with a veterinary dermatologist will help determine if this or another therapy
is the best choice for your pet.
Advantages: addresses the problem directly, a safe
alternative to steroid therapy, can be cheaper in the long run.
Disadvantages: Must see a dermatologist (there are blood
tests that can be taken directly from your general practitioner however skin
testing is typically considered superior), initial cost to see if it works is
much higher than other options, delayed response: can take 2 - 6 months to
begin to show effects .
Glucocorticoids - Steroids
This is one of the most common medications
used for allergies. Unfortunately about half of allergic pets will need some
type of steroid in their pet's regimen. Glucocorticoids are a type of steroid.
Steroids are hormones made from cholesterol in the adrenal glands and gonads.
Glucocorticoids interact with virtually every cell and have the positive effect
of reducing inflammation. Unfortunately this global interaction within the body
is also one of the problems with this therapy. When used at high levels a wide
variety of side effects occur.
Also these steroids don't 'Pump you
up" (they are not anabolic steroids) but can "Plump you up" as
one of their side effects is weight gain. Some other side effects to
glucocorticoids include: increased thirst, increased urine production (which
can lead to accidents in the house), increased hunger, thin and easily bruised
skin, increased blood sugar, diabetes mellitus, decreased calcium absorption,
increased heart contractility, liver disease, pancreatitis, increased blood
pressure, cataracts, glaucoma, gastrointestinal ulceration, behavioral and mood
effects, immune system suppression, muscle breakdown, etc... While this sounds
dismal and these side effects can truly occur, the severity and presence of the
side effects can be controlled by reducing the dosage. How do we do that?
Multimodality. By using other therapies we can reduce the total amount of
steroids used.
What are common steroids used:
Prednisolone, Prednisone, Methylprednisolone , Triamcinolone, and Dexamethasone
. Some pets will respond better to one versus another and some will show less
side effects to one versus another. As a general rule,
prednisolone, prednisone, and methylprednisolone are the most common for
chronic oral use. The others are commonly avoided for long term use.
Short Acting
Cortisone
Hydrocortisone
Intermediate
Acting
Prednisone
Prednisolone
Methylprednisolone
Triamcinolone
Long
Acting
Dexamethasone
Bethamethasone
Paramethasone
Flumethasone
These
also have 3-5 times the potency of the prednisone and up to 25 times the
potency of hydrocortisone.
How much is too much? Doses that are required to suppress the immune system (such as when we treat
allergies), is always going to be higher than the amount of naturally produced
steroids (such as cortisol) by the body. Therefore, we always try to use the
lowest effective dosage of steroids. One guideline for prednisolone (and
prednisone) is 0.5 - 1 mg/kg by mouth every other day ( "Dealing with
Atopy (V61)" Western Veterinary Conference 2008 John MacDonald Auburn
University Auburn, AL, USA). Unfortunately many pets will still have side
effects at this dose. For this reason, Dr Peter J. Ihrke, VMD, DACVD Department
of Medicine & Epidemiology recommends prednisolone to be tapered to
0.5mg/kg by mouth every other day and after a week on this dose, to be further
reduced to its lowest effective dose. Is steroids right for your
pet? This is a question that needs to be
answered with your veterinarian. As a low dose, conjunctive therapy for
allergies, steroids have many advantages. However there may be other safer
options for your pet as well.
Modified Cyclosporine (microemulsified)
Click Here for Atopica Website
Cyclosporine is an immune suppressing compound that is made
by the fungus Beauveria nivea. It
was originally isolated in Norway in 1970. Its primary mode of action is in
inhibiting the actions of the helper T-Lymphocytes. It also affects
T-Suppressor cells, lymphokine production, inhibits release of interleukin-2
and T-Cell Growth factor. It also has some humoral immunosuppressive action.
(Plumb's Veterinary Drug Handbook Fifth Edition). In comparison to
glucocorticoids, cyclosporine is more specific and has less side effects if
used at proper dosing.
Atopica is a Novartis product and is the only FDA and EPA
approved form of cylcospoine for dogs ("The Management of
Canine Atopic Dermatitis" Canine Medicine Symposium 2009 Peter
J. Ihrke, VMD, DACVD Department of Medicine & epidemiology, School of
Veterinary Medicine, University of California, Davis, CA.) The difference from
generic cyclosporine, is that Atopica is a micro emulsified form which provides
enhanced and consistent absorption. This is a medication that the generic form
is generally recommended against as they are are not microemulsified.
What are some of the considerations of
using Atopica?
Cost. It can be fairly expensive.
It can take 4-8 weeks to begin to see
effects. Many times Atopica therapy may be dismissed as not working because a
complete trial was not performed. If an eight week course of Atopica does not
produce any effect, then the medication should be stopped. Atopica site.
It should be given on an empty stomach
Side effects: Atopica uses castor oil as a medium to carry the cyclosporine. When you give castor oil on an empty stomach, it can lead to vomiting and sometimes diarrhea. This might be mistaken as an actual medication reaction instead of just an intolerance to the castor oil. Overall modified cyclosporine at the atopic recommended dose is very safe. Cyclosporine at very high levels can have implications with kidney and liver disease (however this can be said of many medications).
Ketoconazole
Cyclosporine is metabolized by cytochrome P-450 enzymes which are also used with ketoconazole, a
common antifungal. For this reason, concurrent use of ketoconazole can inhibit
the metabolism of cyclosporine. Thus sometimes for financial considerations,
ketoconazole can be added to the regimen to reduce the amount of cyclosporine
needed for therapy. As always, ask your veterinarian first.
