How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Dr. Jo Your Own Question
Dr. Jo
Dr. Jo, Dog Veterinarian
Category: Dog Veterinary
Satisfied Customers: 2808
Experience:  DVM from Iowa State University in 1994; actively engaged in private regular and emergency practice since that time.
Type Your Dog Veterinary Question Here...
Dr. Jo is online now
A new question is answered every 9 seconds

How much injectable penicillin should be given to a lab that

Customer Question

How much injectable penicillin should be given to a lab that weighs 70 to 80 lbs?
JA: Thanks. Can you give me any more details about your issue?
Customer: He has a knot under his chin and is really itching and pulling out his hair.
JA: OK got it. Last thing — Dog Veterinarians generally expect a deposit of about $19 to help with your type of question (you only pay if satisfied). Now I'm going to take you to a page to place a secure deposit with JustAnswer. Don't worry, this chat is saved. After that, we will finish helping you.
Submitted: 1 year ago.
Category: Dog Veterinary
Expert:  Dr. Jo replied 1 year ago.


I'm Dr. Jo and I'm here to help you with your question about penicillin.

Expert:  Dr. Jo replied 1 year ago.

I'm so sorry you're having this problem, but glad you're looking for the information you need. You may join the conversation at any time by typing in what you want to say then clicking REPLY or SEND. Then we can chat back and forth until you're satisfied with the information I've provided.
So I may know we're properly connected and that you understand how the website works (including that I'll need to earn your good rating in order to receive any compensation for helping you), please type in a short response below. You may rest assured you'll have my full attention and will receive a complete response once I know you're there.

Customer: replied 1 year ago.
I would like a text to my question as I requested before.
Expert:  Dr. Jo replied 1 year ago.

Glad you're there. I will happily reply via text below. Typing more now...

Expert:  Dr. Jo replied 1 year ago.

Please understand that I need to word my answer to you very carefully. It would be unethical, illegal, and a violation of the terms of use of this website for me to directly advise you to give your dog any medication whatsoever. If, however, you are simply looking for information, like the amount of penicillin that is typically given to an 80 pound lab, I can happily provide that. The commonly used canine dose for injectable Penicillin G at 300,000 units per ml is 1cc per forty pounds of body weight... or about 2cc. Doses of up to 3cc are not unusual.

That being said, it's important to mention some other things...

  • This may not be effective at solving your dog's problem
  • It may not be safe for use in your particular situation

Does this help you have the information you are looking for so far?

Customer: replied 1 year ago.
What would cause such hair loss in dogs? Could it be allergies? What do you suggest?
Expert:  Dr. Jo replied 1 year ago.

Good questions, all.

The most common causes of hair loss like this in a dog include:

  • allergies
  • mites
  • fungal infections (often secondary to allergies)
  • bacterial infections (often secondary to allergies)

Dealing with hairloss and skin problems in dogs is one of the most complicated things I deal with as a vet. There are so many different causes and the symptoms all look the same. I have to rely on diagnostic tests and often even trial and error to solve each unique case.

Because these cases are so difficult, the quickest and cheapest way for you to get the problem solved for your dog is to start working with a local veterinarian who can do the necessary tests and get a diagnosis. Then you can move forward with the appropriate treatment with a minimum of guesswork.

Expert:  Dr. Jo replied 1 year ago.

In order to drive home the point about how complicated it is to manage a pet with itch and hair loss, I'll share with you the "homework" I send home with my pet owners after I've seen their dogs for this type of problem for the first time.

I'll attach this large document below...

Expert:  Dr. Jo replied 1 year ago.

Itch Relief

The Itching Pet: Alternatives to Steroids

Excessive licking, chewing, and scratching can make a pet’s life miserable for month after month, even year after year. For rapid relief of itch and inflammation, nothing matches the corticosteroid hormones such as cortisone, hydrocortisone, prednisone, dexamethasone, and others.) There are some animals that seem unable to live with any degree of comfort without these medications. Unfortunately, these hormones have widespread and potentially dangerous actions throughout the body when they are used for inappropriately long periods and it is generally desirable to minimize the use of these hormones when possible to do so. Ideally, corticosteroids are used for a few really tough itch weeks and other forms of itch management are used for general itch maintenance.

See more detail on long-term corticosteroid use.

This is, of course, easier to write about than to actually do. When one's pet is scratching and chewing raw spots on his or her skin, practical advice is called for. The following list includes assorted non-steroidal methods for relieving itch and reducing the amount of corticosteroid hormones needed.

Oral Medications

Antihistamine Trials
Histamine, a biological chemical, is the chief mediator of inflammation in humans hence the proliferation of antihistamines available for people both by prescription and over the counter. Histamine is not the major mediator of inflammation in the dog, thus these medications are not as reliable for dogs as they are for us.

The protocol recommended by this hospital is helpful to approximately 40% of dogs who try it. Four different antihistamines are used, one at a time, at least 2 weeks each, in hope of finding one that is acceptably effective. While the chance that an individual antihistamine will be helpful is small (about 15%), trying several antihistamines greatly increases the chance of finding one that works.

Antihistamines are not free of side effects; they are notorious for drowsiness in some individuals. Still, this is vastly preferable to the systemic disruption caused by the corticosteroid group.

Our hospital uses the following antihistamines in a typical antihistamine trial (click for more information):

In cats, antihistamines are substantially more reliable than in dogs so that the chances of a given antihistamine working are usually pretty good. For both cats and dogs, using antihistamines together with a corticosteroid hormone will decrease the amount of corticosteroid hormone needed to control the itching (i.e., less hormone is needed to get the job done if it is given with an antihistamine).

id="Picture_x0020_6" o:spid="_x0000_i1029" type="#_x0000_t75" alt=""
<v:imagedata src="file:///C:\Users\ANIMAL~1\AppData\Local\Temp\msohtmlclip1\01\clip_image002.gif"

Fatty Acid Supplementation
The discovery of anti-inflammatory properties of evening primrose oils and fish oils in humans has led to similar products on the market for our pets. These products are not analogous to the oil supplements that are recommended as food supplements to make a pet's coat shiny; instead; these are true anti-inflammatory drugs capable of relieving joint pain, cramps, and itchy skin.

The supplement alone is helpful in 10% to 25% of itchy dogs; we often recommend its use in combination with antihistamines to boost the efficacy of the protocol described above.

Cyclosporine (Atopica)

Cyclosporine is an immune system modulating drug originally developed for use in organ transplant patients, but which is also useful in other immune-mediated diseases. Since allergy is an immune-mediated condition, cyclosporine was investigated as an alternative to corticosteroids and found effective for most patients. Currently this medication is being marketed only for dogs and one dog in three will develop an upset stomach when starting the drug (though this resolves or is manageable with dose modification).

Topicals to Try

When using any dip on inflamed skin one should be aware that the use of cool water is considered much more soothing than warm water.

Colloidal Oatmeal Shampoos and Creme Rinse - At first, these products were only available for human use, as powdered soaks to pour into bath water.

id="Picture_x0020_7" o:spid="_x0000_i1028" type="#_x0000_t75" alt=""
<v:imagedata src="file:///C:\Users\ANIMAL~1\AppData\Local\Temp\msohtmlclip1\01\clip_image003.gif"

Once their value in itch management was determined, their use quickly spread to the veterinary field. Colloidal oatmeal actually pulls inflammatory toxis out of the skin, generally yielding 1 to 3 days of relief. The creme rinses are meant to yield longer acting relief. They are available plain or combined with local anesthetic forumlas to soothe itch.

Lime Sulfur Dip - This product kills parasites, ringworm fungi, and bacteria.

id="Picture_x0020_8" o:spid="_x0000_i1027" type="#_x0000_t75" alt=""
<v:imagedata src="file:///C:\Users\ANIMAL~1\AppData\Local\Temp\msohtmlclip1\01\clip_image004.gif"

It also dries moist, weeping skin lesions and helps dissolve surface skin proteins that are involved in itchiness. Many veterinary dermatologists recommend it regularly to control itch; however, it has several disadvantages. It smells terrible. The sulfur ingredient smells like rotten eggs and this is how your bathroom or bathing area will smell during the pet's bath. This dip can stain jewelry and clothing and will temporarily turn white fur yellow.

Other Shampoos
Itchy skin can be the result of skin infection, excess oil accumulation, yeast infection, even parasitic infection. The list goes on. The shampoo products listed above can be used against any itchy skin disease but it should be noted that there are many other shampoo and creme rinse products that can be used against the specific skin diseases listed. If some other type of shampoo product has been prescribed to you for an itchy skin disease, it is important that you use it allowing at least a good 10 minutes of skin contact time before rinsing.


Other Topical Products

Colloidal Oatmeal Sprays and Lotions - Same principle as above. These products pull inflammatory toxins out of the skin. Oatmeal products have become very popular and are available as shampoos, creme rinses, soaks, sprays, and lotions.

Humilac Spray - This moisturizer may be applied as a spray or mixed in water as a dip. It is helpful for dry skin but can also be used in combination with lime sulfur as lime sulfur is naturally drying to the skin.

Witch Hazel - This product has a cooling effect on the skin that is soothing for both animals and for people with sun burn. It is available as a spray or lotion.

Aloe Vera Gel - If possible, obtain 100% aloe vera gel from a health food store. Products containing aloe are much more available but are generally not as effective and not meant to be licked away by a pet. Aloe vera gel comes from the aloe vera succulent and contains enzymes which break down inflammatory proteins and enhance healing. Pure aloe vera gel is not harmful for pets who want to lick it off.

Topical Steroids? - It seems clear that taking steroids orally may be harmful to the body with chronic use but are topical cremes safe for long term use? We now know that topical steroids (cortisone cremes and related products) are absorbed through the skin and into the bloodstream but the hormonal side effects with topical use do seem blunted. For small irritated areas (hot spots), topicals can provide excellent relief without the systemic effects of hormones.

Respect the Steroid

Severe itching amounts to a reduction in life quality. It is important not to develop the mindset that corticosteroids should be avoided at all costs. This would not be fair to the itching pet. Steroids are valuable tools in the relief of pain and suffering and have an important place the therapy of the itchy pet. The goal is not to avoid steroid use if possible but to avoid long term dependence on steroids if possible. Despite all of the above management tricks, some pets will still require long term steroid use to achieve any reasonable comfort. There are monitoring protocols in place for such cases. It should also not be forgotten that underlying allergies and recurring skin infections can be addressed specifically and that as these conditions are managed, the itch is also managed.

Steroid hormones have many side effects and, as helpful as they are for allergic skin diseases, it is best to reserve them for only the most itchy episodes.

Airborne Allergies


Everyone knows someone with hay fever. Airborne pollens, molds, dust particles, etc. are inhaled and soon the sneezing and sniffling begins.

id="Picture_x0020_1" o:spid="_x0000_i1026" type="#_x0000_t75" alt=""
<v:imagedata src="file:///C:\Users\ANIMAL~1\AppData\Local\Temp\msohtmlclip1\01\clip_image005.jpg"

A simple way to think of atopy for pets would be simply saying that the pet inhales an airborne allergen but instead of sneezing and sniffling, the pet gets itchy skin. In fact, the situation is probably far more complex. The allergen is not only inhaled but is in contact with the skin and it is no longer considered accurate to think of atopy as an inhaled allergy. Exactly how we get from particles floating in the air to itching and scratching is not entirely understood but the important issue is that the allergen comes from the air.

Airborne particles (pollen, dander, etc.) are harmless to someone who is not allergic to them. Allergy develops in individuals who are genetically programmed to do so.

Breeds predisposed to develop atopy include: Dalmatian, Golden retriever, West Highland white terrier, Shar Pei, Labrador retriever, Cairn terrier, Lhasa Apso, Shih Tzu, Boxer, and Pug.

Features of Atopy

There are many reasons for pets to itch: parasites, allergy to flea bites, food allergy, secondary infection and the list goes on. The following findings in the history and examination of the patient might lead to a diagnosis of atopy.Atopy usually produces a seasonal itchiness though after several years, the duration of the itchy period extends. Finally, the pet is itchy nearly all year round.

In dogs, atopy usually produces a seasonal itchiness though after several years, the duration of the itchy period extends. Ultimately, the dog is itchy nearly all year round in 80% of cases. In cats, unfortunately, seasonality is not nearly as reliable a feature.

Young age of onset
Seasonal itchiness due to atopy tends to begin early in a pet's life (between ages 1 and 3 years in 70% of dogs diagnosed with atopy). Food allergy tends to begin later, more like age 5 or 6 years in dogs. Age at which itching first manifests is not as reliable a sign in cats as in dogs.

Good response to steroids
Whether the patient is a dog or cat, itchiness due to atopy responds rapidly to cortisone-type medications (prednisone, DepoMedrol, dexamethasone, etc.) as does itching due to insect bite allergy. Food allergy is more variable in its response; it may or may not respond well.

id="Picture_x0020_5" o:spid="_x0000_s1033" type="#_x0000_t75" alt=""
<v:imagedata src="file:///C:\Users\ANIMAL~1\AppData\Local\Temp\msohtmlclip1\01\clip_image006.jpg"

A few reactive blebs on an intradermal skin test

A positive intradermal skin test
Intradermal skin testing is generally done to put together a set of allergens to make allergy shots. Hair is clipped from an area of non-inflamed skin and small samples of different allergenic proteins are injected into the skin. An atopic patient should react to an allergen by showing swelling and redness in the injection area. In most cases, this kind of testing is done after a diagnosis of atopy has been made based on other factors. This is not generally done to diagnose atopy but is done as part of the preparation for hyposensitization (see below). Sometimes, however, a diagnosis is elusive. In such cases, seeing a field of positive and negative skin blebs (flaccid vesicles) helps build confidence that atopy is the cause of the patient's itching. There are blood tests that can also be helpful in preparing for hyposensitization but it is important not to consider them as tests “for atopy.” They are instead tests of antibody levels and are used to help pick allergens for serum.

Typical irritation pattern
Atopy is associated with irritation in certain parts of the body. In dogs these areas are:

id="Picture_x0020_2" o:spid="_x0000_i1025" type="#_x0000_t75" alt=""
<v:imagedata src="file:///C:\Users\ANIMAL~1\AppData\Local\Temp\msohtmlclip1\01\clip_image007.gif"

It should be noted that food allergy has a similar irritation pattern but a different history. Flea bite allergy, the most common form of allergic skin disease in pets, has a different irritation pattern.

In cats, the irritation pattern is not as characteristic. There are four common manifestations of atopy:

{C}<v:shape id="Picture_x0020_6"
o:spid="_x0000_s1032" type="#_x0000_t75" alt=""
<v:imagedata src="file:///C:\Users\ANIMAL~1\AppData\Local\Temp\msohtmlclip1\01\clip_image008.jpg"

Non-lesional fur mowing

{C}<v:shape id="Picture_x0020_7"
o:spid="_x0000_s1031" type="#_x0000_t75" alt=""
<v:imagedata src="file:///C:\Users\ANIMAL~1\AppData\Local\Temp\msohtmlclip1\01\clip_image009.jpg"

Eosinophilic granuloma complex

{C}<v:shape id="Picture_x0020_8"
o:spid="_x0000_s1030" type="#_x0000_t75" alt=""
<v:imagedata src="file:///C:\Users\ANIMAL~1\AppData\Local\Temp\msohtmlclip1\01\clip_image010.jpg"

Miliary dermatitis (small seed-like scabs)

{C}<v:shape id="Picture_x0020_9"
o:spid="_x0000_s1029" type="#_x0000_t75" alt=""
<v:imagedata src="file:///C:\Users\ANIMAL~1\AppData\Local\Temp\msohtmlclip1\01\clip_image011.jpg"

face and ear itching

Unfortunately, these same irritation patterns can be found in numerous other skin conditions and, in fact, up to 25% of atopic cats have multiple types of allergies.

While it would be nice to have a blood test that could tell us if a pet’s itching is due to atopy, it is important to realize that such a test does not exist. Atopy remains a clinical diagnosis, which means the diagnosis is made based on history and examination findings.

Treatment Options

Before doing anything else, it is important to clear up secondary infections. Secondary infections involve bacteria (usually Staphylococcal) and/or yeast (Malassezia) at the site of the itchiest areas. These organisms live naturally in the skin but when the skin is irritated, they gain access to inner tissue layers and proliferate. Sometimes they generate further allergic response. These infections tend to be recurrent and are the usual cause of recurrence of itch symptoms in a patient previously controlled.

Making the Skin Less Reactive

Since it is unlikely that the patient is going to be able to avoid airborne allergens (pollens, for example, travel miles in the breeze), we are left with treating the patient. For short episodes of itching during the itchy season, cortisone-type medications are highly effective. When the pet becomes more chronically itchy, cortisones become less feasible because of their long-term side effects and other options must be considered.

Steroid Hormones
These cortisone-type medications (prednisone, prednisolone, triamcinolone, dexamethasone etc.) tend to be useful as the first line of defense against itchy skin. A higher dose is used at first but this is quickly tapered down once the condition is controlled. Prednisone, for example, is given every other day so as to allow the pet one day of recovery from the prednisone's hormonal actions. An atopic dog will respond within days. For cats, long-acting cortisone-type injections are commonly used as cats are frequently not amenable to taking pills.

Side effects include:

  • Excess thirst
  • Excess hunger
  • Excess urination (which can lead to house-breaking issues)
  • Suppression of the immune-system/bringing out latent infection (especially urinary tract infection and upper respiratory infection.) Raising blood sugar/destabilizing a borderline diabetic (especially a problem for cats). In the short term, side effects can be controlled by adjusting dosage but in the long term, these medications are more problematic and if possible their use should be minimized.

Omega 3 Fatty Acid Supplements
These products are NOT analogous to adding oil to the pet's food. Instead, these special fatty acids act as medications, disrupting the production of inflammatory chemicals within the skin. By using these supplements, it may be possible to postpone the need for steroids/cortisones or reduce the dose of steroid needed to control symptoms. It takes a good 6 weeks to build up enough omega 3 fatty acids in the body to see a difference.

These are far less harmful than prednisone but only 10-20% of dogs will respond to any given antihistamine. Fortunately, there are numerous antihistamines to try and often it is possible to find one that works by trying a different one sequentially. In contrast to dogs, cats are far more responsive to antihistamines; the downside is having to give a cat medication twice daily. Antihistamines and omega 3 fatty acids synergize with each other so it is a good idea to use omega 3 fatty acids in conjunction with antihistamines.

Cyclosporine is a modulator of the immune response that has been very helpful in organ transplant patients both human and non-human. It has been found to be as reliably effective in atopic dermatitis in the dog as steroids and does not carry the unpleasant side effect profile that steroids do. It is used mostly in dogs but can also be used in cats. For more details on this medication click here.

This is a new drug still under development. It addresses mast cells, the cells that carry the

inflammatory biochemicals of allergy. It is currently available on a very limited basis through its manufacturer as part of clinical research.

Reducing Allergin Exposure

The following are some general tips for minimizing allergen exposure.

Bathing the pet weekly to remove allergens from the fur may be helpful in reducing allergen exposure. There are also many therapeutic shampoos that can be used to restore the skin’s natural barrier or to assist in general itch relief. For more details, see our section on Itch Relief.

  • Avoid stuffed toys and wash bedding regularly to minimizes dust mite exposure. Also, remove the pet from the area when vacuuming or dusting.
  • Use air-conditioning and/or an air filter system.
  • Keep the pet away from the lawn while it is being mowed.
  • Minimize houseplants.


Just as people have allergy shots, so can pets; however, the process is not without difficulty and you should not expect hyposensitization to end all itchy skin concerns.

Allergy shots require approximately 6 to 12 months to begin working.

25% of atopic dogs will not respond (these are usually the animals allergic to multiple allergens).

25% will require prednisone or a similar steroid at least at some times.

You will most likely have to give the allergy shots yourself.

In hyposensitization the patient is injected with small amounts of allergens on a regular basis. As time passes, the amounts of allergens increase and injections are given at longer intervals. The selection of allergens is made based on the results of an intradermal skin test (as described above), an in vitro test (a blood test) or a combination of the results of both tests.

Is your Pet a Candidate for Skin Testing?

Testing is best done during your pet's non-itchy season (if there is one) so that the skin responses of the test will not be clouded by active inflammation. The test involves injections of small amounts of allergen extracts into the skin. Reactions noted are compared to reactions produced by two controls: pure histamine (very inflammatory) and pure saline (very non-inflammatory).

In order for skin testing to be performed, medications must be discontinued well in advance. How long in advance depends on the medication and on the policies of the veterinary dermatology practice that will be doing the test. Oral steroids, for example, commonly require a full month of discontinuance, which can be problematic if the pet is highly dependent on medication for life quality.

In Vitro Testing

In vitro testing does not always require withdrawal of medications nor does it require referral to a specialist. There is no hair clipping and sedation is rarely necessary. Blood is simply drawn and checked for antibodies against common allergens for that geographic region. A profile is reported and allergens can be selected accordingly. It is important to remember that these results do not necessarily imply that the patient is allergic to substances reported; this is simply a test for antibodies. Antibody elevations are common with levels changing based on an assortment of factors (whether the pet has parasites at the time of the test, how common the substances being tested are, how long medications have been used prior to the test etc.) and interpretation of the profile is part of the “art of veterinary practice.”

For more details on what is involved, see our page on allergen-specific immunotherapy (allergy shots).

Expert:  Dr. Jo replied 1 year ago.

Food Allergies

The Pet Health Care Library

{C}<v:shapetype id="_x0000_t75"
coordsize="21600,21600" o:spt="75" o:preferrelative="t" path="[email protected]@[email protected]@[email protected]@[email protected]@5xe"
filled="f" stroked="f">
<v:shape id="Picture_x0020_2" o:spid="_x0000_s1028"
type="#_x0000_t75" alt=""
<v:imagedata src="file:///C:\Users\ANIMAL~1\AppData\Local\Temp\msohtmlclip1\01\clip_image001.gif"

The classical canine food allergy lesion distribution includes signs of facial itching, foot or limb chewing, belly itching, and recurrent ear infections.

{C}<v:shape id="Picture_x0020_3"
o:spid="_x0000_s1027" type="#_x0000_t75" alt=""
<v:imagedata src="file:///C:\Users\ANIMAL~1\AppData\Local\Temp\msohtmlclip1\01\clip_image002.gif"

In cats, food allergy usually produces scabs and other signs of itching around the face or neck.

(Only some of the captioned signs are usually present in a given animal, not necessarily all.)

Your Pet's Itchy Skin

Itchy skin in the small animal is often more than just a minor annoyance. Red, oozing bald patches; rashes; and large expanses of hair loss are unfortunate markers of very real discomfort for which a cause should be sought and dealt with.

The food allergy is one of the itchiest conditions known to cats and dogs. Animals eat a variety of processed food proteins, fillers, and colorings that are further processed inside their bodies. Proteins may be combined or changed into substances recognized by the immune system as foreign invaders to be attacked. The resulting inflammation may target the gastrointestinal (GI) tract or other organ systems, but in dogs and cats it is the skin that most often suffers from this immunologic activity.

Many people erroneously assume itching due to food allergy requires a recent diet change of some sort. In fact, the opposite is true.

Food allergy requires time to develop; most animals have been eating the offending food for years with no trouble.

What Kind of Allergy?

Sarcoptic mange and inhalant allergy (also known as atopy) are the two conditions which must be distinguished from food allergy as the treatment approach to each is markedly different. Much time and money can be wasted pursuing the wrong problem.

Please consider the following clues that contribute to pointing us towards the food allergy as a diagnosis. Your pet demonstrates:

  • Your pet has been treated for sarcoptic mange without any positive change.
  • Your pet's itchiness is not and has never been a seasonal problem.
  • Your pet has responded poorly or only partially to cortisone-type medications.
  • Your pet has had a skin biopsy demonstrating changes often associated with allergy or, more specifically, food allergy.
  • A lesion distribution pattern that is common for food allergy (see illustration above).
  • Your pet did not have skin issues before age 5 or 6.

Any of the above findings or observations warrant pursuit of food allergy.

Note that three of the above four criteria relate to what you, the owner, observe at home. Trouble results when the veterinarian must speak to different family members about the pet and there is disagreement in their observation of the pet at home. It is best to have one person, preferably the one who has the most contact with the pet, be the spokesperson and make the relevant judgments.

The Flea Factor

Some animals have many allergies. It would not be particularly unusual for an animal with a food or inhalant allergy


{C}<v:shape id="Picture_x0020_4"
o:spid="_x0000_s1026" type="#_x0000_t75" alt=""
<v:imagedata src="file:///C:\Users\ANIMAL~1\AppData\Local\Temp\msohtmlclip1\01\clip_image003.gif"

to also be allergic to flea bites, especially considering that flea bite allergy is extremely common among pets. Because allergies add to each other, it is possible that a food-allergic dog will not itch if its fleas are controlled. Since new technology has made flea control safe and convenient, it is especially important (and no longer difficult) to see that fleas are not complicating a pet's itching problem.

Ensure immaculate flea control for any itchy pet!

See more information on flea biology and flea control.

How to Deal with the Food Allergy Suspect: The Hypoallergenic Diet Trial

The Basic Principle

To determine whether or not a food allergy or intolerance is causing the skin problem, a hypoallergenic diet is fed for a set period of time. If the pet recovers, the original diet is fed for up to two weeks to see if itching resumes. If we see recovery with the test diet and itch with the original diet, then food allergy is diagnosed and the pet is returned to either the test diet or another appropriate commercial food indefinitely.

What is a Good Hypoallergenic Diet?

There are two approaches to this question. Obviously, the test diet must be of a food source that the patient could not possibly be allergic to. The traditional method is the use of a novel (new to the pet) protein and carbohydrate source; that is, something the pet has never eaten before. In the past, lamb has been the protein source of choice as American pet food companies had traditionally failed to produce lamb-based pet foods. Unfortunately, recent production of lamb and rice-based foods has removed lamb from the acceptable hypoallergenic diet list for most pets.

Fortunately, many pet food companies have discerned the need for diets using unusual protein and carbohydrate sources with a minimum of additives. Foods can be obtained based on venison and potato, fish and potato, egg and rice, duck and pea, and even kangaroo. Diets used for allergy trials must contain basically one protein and one carbohydrate source and neither can be something the pet has had before. Recently several diets that include duck, venison, and so on have been released to the general market. Be aware of foods that contain these ingredients because these ingredients will not be useable for future diet trials if they were ever used in the pet's regular food.

It is important that no unnecessary medications be given during the diet trial. No edible chew toys (such as rawhides or bones) should be given. Treats must be based on the same food sources as the test diet. (Beware of rice cakes, though, as wheat is commonly used as a filler.) Chewable heartworm preventives should be replaced with tablets.

Home cooking was originally the only option felt to be appropriately free of allergens but for most animals these special commercial foods are adequate. Occasionally home cooking ends up being necessary after all. Recipes for appropriate diets can be purchased through, a website set up by the American College of Veterinary Nutrition.

The Hydrolyzed Protein Method

Recently a new approach has been introduced using therapeutic diets made from hydrolyzed proteins. This means that a conventional protein source is used but the protein is broken down into molecules too small to excite the immune system. Some hydrolized diets are on the market; discuss with your veterinarian which is best for your pet.

How Long to Feed the Trial Diet

In the past, four weeks was thought to represent a complete trial period. More recent work has shown that only one food allergic dog in four will respond within this time frame and that a more appropriate trial period would be 10 to 12 weeks. This may be an extremely inconvenient period of time to home cook. Some veterinarians recommend a recheck appointment or a phone call after four weeks of diet trial and then again after 8 weeks. Eighty percent of food-allergic dogs will have responded to diet trial at least partially by six weeks. The Labrador retriever and cocker spaniel appear to require longer trials.

Most commercial diets used in food allergy trials have a 100% guarantee. This means that if your pet doesn’t like the food, the food can be returned for a complete refund, even if the bag is opened. This is especially helpful for feline patients, as cats are famous for being choosy about what they are willing to eat.

What to do if the Diet is Successful?

To confirm food allergy, return to the original food; itching resumes within 14 days generally if food allergy was truly the reason for the itchy skin. Many people do not want to take a chance of returning to itching if the patient is doing well; it is not unreasonable to simply stay with the test diet if the pet remains free of symptoms. Often it is difficult to remember 10 to 12 weeks later how itchy the dog used to be before the diet trial. The diet challenge helps make it more obvious whether the diet trial has worked or not.

It is possible to more specifically determine the identity of the offending foods after the pet is well. To do this, a pure protein source (such as cooked chicken, tofu, wheat flour or any other single food) is added to the test diet with each feeding. If the pet begins to itch within 2 weeks, then that protein source represents one of the pet's allergens. Return to the test diet until the itching stops and try another pure protein source. If no itching results after two weeks of feeding a test protein, the pet is not allergic to this protein.

What to do if the Diet is Unsuccessful?

Assuming secondary skin infections have been controlled, an unsuccessful food trial is strongly suggestive that an inhalant allergy is the primary problem but there are some other considerations that should at least be mentioned:

  • Are you certain that the dog received no other food or substances orally during the trial?
  • Was sarcoptic mange ruled out?
  • Your pet may require a longer diet trial. Are you certain regarding the factor which pointed toward the food allergy?

If your pet has not been biopsied, now may be a good time. If an inhalant allergy has risen to the top of the list, symptomatic relief either via medication, baths with specific shampoos, or allergy shots will likely be necessary. Chronic itchiness can be extremely uncomfortable and prompt relief is our goal as well as yours.

Information on itch relief.
Information on airborne allergies.
Information on sarcoptic mange.

See a veterinary nutritionist's thoughts on Food Allergy Trials in Dogs.

For treats appropriate to dogs on a food trial see: for sweet potato treats; for rabbit ear treats, venison sausage, carrot dental bones, turkey jerky strips, rabbit ear treats, Icelandic fish chews, and other novel protein-based treats.

Other acceptable products include those made of pig parts: ears, snouts etc.

Allergies are a common problem for dogs. Typical symptoms include itchiness resulting in excess scratching, biting, or licking, and sometimes chronic or recurrent skin/ear infections. While dogs most frequently suffer from allergies to environmental triggers (e.g., pollen, molds, and dust mites or flea bites), allergic reactions to food are possible, and are frequently a source of greater controversy.

Diagnosing canine food allergies is not easy. It typically requires a food trial during which a dog eats ABSOLUTELY NOTHING other than a food containing protein and carbohydrate sources to which he has never been exposed before. Another option is to only allow your dog to eat food that has been processed in such a way as to make it hypoallergenic. A food trial needs to continue for at least eight weeks before its success or failure can be evaluated. This is easier said than done!

I think the difficulty we have in definitively diagnosing food allergies in dogs is at least partially responsible for some of the myths that have developed around the condition. Let’s look at a few, along with the truths behind them.

Myth: Dogs are typically allergic to corn, wheat, soy, and other plant-based ingredients.

Truth: In a study of 278 cases of food allergies in dogs where the problem ingredient was clearly identified, beef was by far the biggest culprit (95 cases). Dairy was number two at 55 cases. Wheat came in third with 42 cases. Soy and corn were actually minimal offenders, coming in at 13 and 7 cases, respectively.

In fact, protein sources are more often to blame than grains. Beef, dairy, chicken, egg, lamb, soy, pork and fish were responsible for 231 of the food allergies, while wheat, corn and rice combined accounted for only 54. (Some dogs were allergic to more than one ingredient, which is why these numbers total more than 278.)

Myth: "I’ve changed my dog’s diet several times and he’s still itchy, so he can’t have a food allergy."

Truth: Dogs are allergic to particular ingredients, not to brands or types of food. So if your dog is allergic to chicken, and each of the foods you have tried contains chicken, he will still be itchy. Look very closely at the ingredient list; it will usually contain multiple protein and carbohydrate sources. It is not unusual for a food that is labeled "lamb and rice," for example, to contain chicken or other potential allergens as well.

It is difficult to guess correctly as to what your dog might be allergic to, which is why veterinarians typically reach for foods with novel ingredients like venison and potato (your dog’s dietary history is important for picking out the right one), or specially processed, hypoallergenic foods.

Myth: "I haven’t changed my dog’s diet. It’s hard to believe that he would be developing a food allergy now."

Truth: Dogs can develop food allergies at any time in their life, and with any dietary history.

Myth: "If my dog is suffering from food allergies, why doesn’t he have diarrhea?"

Truth: Some, but not all, dogs with food allergies have concurrent gastrointestinal signs like vomiting or diarrhea, so you shouldn’t rule out food allergies just because his GI tract seems to be functioning normally. If your dog has chronic gastrointestinal problems in addition to non-seasonal itchiness, a food allergy will be at the top of the list of potential problems.


If you think that your dog could have a food allergy, talk to your veterinarian. He or she can help you find the right food to keep your dog’s symptoms at bay while still providing the balanced nutrition that is essential to good health.

Expert:  Dr. Jo replied 1 year ago.

Sorry... it looks like the images in that document didn't cut and paste, but I think you can still get the idea.

Does this help to answer your question at this point in time? I want to be as helpful as possible because I know this is a really frustrating situation.

Expert:  Dr. Jo replied 1 year ago.

Is there anything else I can help you with?

Expert:  Dr. Jo replied 1 year ago.

Please remember I am here for you and am happy to discuss your question until you are satisfied with the answer I've provided. You may return to this page at any time to review this information and/or post more. You may do so even after you've rated my response. I'll be notified of your response via email and will do my best to help you.
If you are satisfied with the information I've provided, please take a moment to rate my response. I've done my best to provide you with the most accurate, thorough and up-to-date information that is available, and your positive feedback is important to me. Without it, I receive no compensation for helping you.
If you are not satisfied, please let me know how else I may be of assistance.
Thank you for using our website.

Expert:  Dr. Jo replied 1 year ago.


Just checking in to ask how things are going with your dog. Is there anything else I can help you with?

Thank you,

Dr. Jo

Related Dog Veterinary Questions