Dog Allergy Symptoms

While not usually life threatening, allergies in dogs do cause discomfort. Most symptoms are associated with dermatologic problems but some can also lead to chronic respiratory issues in some dogs if untreated for long periods of time. Sometimes an owner will bring their dog to a veterinary appointment, suspecting a serious medical condition and end up finding out that their canine companion has an allergy. 
Here are some allergy symptoms commonly found in dogs:
  • Excessive licking
  • Compulsive scratching
  • Periodic chewing on the same or different body parts or areas
  • Regularly rubbing body or body parts against the ground, walls, furniture, etc. 
  • Frequent sneezing and/or wheezing
  • Skin irritation/fur loss
Most allergies develop after the second year of life for dogs. In the first year, the dog will be exposed to many types of allergens primarily through contact with the skin. A smaller number of allergies may be caused by food (usually the protein source) and inhalant (things they breathe in that are in the air). In the second year of life, the dog’s immune system will overreact to the antigen(s) causing release of immune cells which release inflammatory substances ( such as histamine) which lead to symptoms of itching. Rarely is a dog allergic to just one thing. Most allergic dogs are born with a less than optimal skin barrier which allows for antigens to enter the skin more easily. Dogs that suffer from allergies have abnormal skin and a less than optimal immune response which allows for secondary infections to occur. Typically, dogs do not suffer from a single allergy, but instead, dogs with sensitivities to allergens have a host of issues. You must understand that dog allergies are due to a complex set of issues that tends to change as the dog’s environment changes.
Because these symptoms can have several possible causes, we recommend making a veterinary appointment immediately if you notice your dog exhibiting any of the above symptoms. Early diagnosis and treatment of dog allergies not only increases the likelihood of your dog’s treatment being successful, but can also be less expensive than delaying treatment.  The longer you wait, the more your dog suffers and more severe the secondary infections can become.

Dog Allergy Testing

The first step to determining the cause of your dog’s symptoms is a thorough exam by your veterinarian. In addition to looking for external skin parasites such as fleas and mites, your veterinarian will want to do some diagnostics to help him/her determine what types of infections may be present. After diagnosing and treating for external parasites and infections, your veterinarian may want to discuss allergy testing. Once your veterinarian believes that allergies are the root cause of skin irritation/infections and discomfort, then they may recommend testing for specific allergens. There are many things to test for in determining what your dog may be causing the allergies for your dog. Dog allergens fall into the following groups:
  • Contact allergy - including many grasses and plants, dust mites and molds
  • Flea allergies - many dogs are highly allergic to flea bites
  • Food allergies - including different types of proteins 
  • Inhalant allergy (Atopy) - allergens that are inhaled
Contact allergies such as flea, food and dust/pollen allergies are  by far the most common cause of allergies in dogs. These allergens can cause an allergic reaction in the body that focuses largely on and within the epidermis, causing severe irritation. The result is a dog scratching itself to the point that skin infections and injuries can occur.

There Are Two Main Types Of Dog Allergy Testing

Blood Testing and Intradermal Skin Testing. Each type of canine allergy testing administered differently and has its benefits and drawbacks. However, the following points hold true for both types of dog allergy testing:
It is best to perform these test during the season(s) when the allergy is the worst and therefore most likely to generate an accurate result
Testing should come after examination for other potential causes and irritators, including:
  • Fleas
  • Mites
  • Fungal or yeast infections of the skin (common secondary invaders)
  • Chronic bacterial infections (common secondary invaders)
  • Hypothyroidism
A veterinarian might also order a 12 week hypoallergenic diet to rule out a food allergy. Food allergies are difficult to detect using either dog allergy testing method, and therefore should be determined through dietary manipulation. Once all of these possibilities are ruled out, the veterinarian will order either a blood or skin test to determine the presence of dog allergies.

What Causes A Dog To Develop  Allergies?

Think of dogs skin like saran wrap. It covers and protects the dog. However, dogs with allergies are born with abnormal skin (like holes in the saran wrap). These abnormalities in the skin allow for the allergens, which are normal in all environments, to enter thru the skin layer and set off an allergic response which causes itching and redness. So, it is important to understand that dogs who suffer from contact allergies do not have normal skin. Additionally, these dogs do not have a healthy immune response.
In addition, this inflammation in the skin will change the health of the skin and allow for secondary invaders such as bacteria and yeast to enter the dog’s system. In addition, many of these dogs have a less than optimal local immune response to these secondary invaders making them more susceptible to yeast and bacterial infections. Yeast and bacteria are always present in low numbers on every dog’s skin. Unfortunately for dogs with allergies, their skin and immune response are inadequate to fight off these secondary invaders.

Blood Allergy Testing

Blood allergy testing is the most common form of allergy testing because it is convenient and easy to do. To perform a blood allergy test, a small sample of the patient’s blood is drawn and analyzed. It is then tested for a reaction to a vast array of geographically appropriate allergens, including:
  • Pollens
  • Dusts
  • Molds
Blood allergy tests can also determine food allergies, as well as allergic reactions to materials like cotton or nylon. Blood tests are much less invasive and time consuming than skin allergy tests. Blood tests are the most commonly used dog allergy test.

Skin Allergy Testing

Skin allergy testing for dogs is another form of allergy testing used by veterinarians and veterinary dermatologists today. Skin allergy testing is more invasive than blood allergy testing, because it requires sedation due to the length of time the patient needs to be still. To perform skin allergy testing for dogs:
  • The patient is sedated
  • The patient is placed on its side
  • A small area on the patient’s side is shaved
  • Small needles inject tiny amounts of each test allergen just under the patient’s skin in a specific pattern and order so that if the dog shows a small raised reaction, the allergen causing it can be identified
After a period of time (usually a few hours), the shaved area is examined to determine which allergens elicited a reaction. Based on what the pattern indicates, a veterinarian and/or veterinary dermatologist can prescribe the most effective treatment protocol. Skin allergy testing for dogs has been estimated to be upwards of 75% accurate in determining the presence of dog allergies. However, skin allergy tests can be inaccurate if patients have received antihistamines or steroids in the months leading up to testing. Your veterinarian can help determine if skin allergy testing is appropriate and will yield accurate results for your canine friend. 

Treating allergies in Dogs

It is helpful to understand that allergies cannot be cured but can be successfully treated. There are many types of treatment and include the combination of oral medication, bathing, topical therapy and even injectable antigen therapy.
Prescribing the correct allergy medicine for dogs depends largely on the symptoms that the dog is displaying, the severity of the symptoms, and preexisting medical conditions. Allergy medicine for dogs may involve one or more of the following types of therapies:
  • Anti-inflammatory therapy: Treats dog allergies with anti-inflammatory drugs such as corticosteroids, or with antihistamines that quickly block the allergic reaction in most cases. 
  • Immune modulators: These modify and reduce the dog’s immune response to reduce the amount of itching which occurs from exposure to the antigens
  • Food and Dietary supplements: These include the use of protein select diets and  supplementation of fatty acids.  Some dogs have allergies just to food and some may also have a food allergy and/or contact allergies. The use of Omega three fatty acids can help improve the patient’s response to steroids and antihistamines in some cases
  • Antipruritic therapy (anti-itch): These includes antihistamines, corticosteroids and a new medication known as Apoquel which specifically targets the itch response by blocking the substances in the body which cause itch
  • Shampoo therapy: Bathing can be very helpful to remove the antigens the dog has been exposed to and also to remove dead skin cells and help treat secondary infections such as yeast and bacteria. Some therapeutic shampoos contain anti-inflammatory ingredients that may further benefit your dog
  • Hyposensitization therapy: If the specific offending allergens are identified by allergy testing, allergy shots can be given to the patient. This form of allergy medicine for dogs consists of weekly injections of very small amounts of an antigen. Repeated dosing helps reprogram or desensitize the patient’s immune system. Approximately 50% of treated dogs will see significant improvement in their clinical signs, while approximately 25% more will see a decrease in the amount or frequency of anti-inflammatory therapy
To learn which allergy medicine for dogs, and what dog allergy treatment methods will work best for your canine friend, schedule an appointment with your veterinarian today. Every allergy case is different and must all be approached on a case by case basis.  

Choosing The Best Dog Food For Allergies

Some dogs suffer from food allergies.  The only way to determine food allergies is to do an elimination diet in which we change your dog’s diet to a limited list of ingredients that contain no known allergens. These can be home cooked or commercial diets(prescription) specifically made for food allergic dogs.
We can help determine whether or not your dog has a food allergy by prescribing three possible diets:
  • Limited ingredient diet: We limit the ingredients of your dog’s diet to pin down the specific allergen causing your dog’s reactions
  • Novel ingredient diet: We introduce ingredients your dog has not been exposed to and is therefore less likely to be causing the reactions
  • Prescription diet: We prescribe a kibble-based or ingredient specific diet that is designed to contain hypoallergenic ingredients
It is important to remember that only about 10% of all dog allergies are food-based. Also, it is important to designate between dog food allergies and dog food intolerances. For clarification:
  • A food allergy occurs when a dog’s immune system mistakenly identifies a particular food ingredient as harmful, and subsequently creates defensive antibodies to fight the invading enemy
  • A food intolerance is a digestive problem, not an immune response. A food intolerance occurs when a dog’s digestive system is unable to digest a specific ingredient 
Therefore, choosing the best dog food for allergies should be part of a larger allergy awareness and testing protocol. Doing so ensures your are not overlooking any one component of dog allergy testing that will help lead to the overall health and wellness of your canine friend. 

Frequently Asked Dog Allergy Questions


I Have Been Told That My Dog Is Atopic. Is This The Same As Transdermal Allergy?

Yes. After flea allergy dermatitis (FAD), atopy is the second most common type of allergy in the dog. It is caused by topical allergens to which the dog’s immune system overreacts. Most dogs (70 percent) begin to show signs between one and three years of age, but can start as early as one month or as late as six years. Most allergies that begin under six months or over six years of age involve food.

What Exactly Causes It?

  • In general, dogs with allergies have an abnormal skin barrier and and less than optimal immune system at the skin level.  This type of skin allows for antigens to enter the skin easier and allows for infections to occur more frequently.
  • There are a wide variety of allergens that can cause atopy. The affected canine may have come in contact with dust, pollens or molds, where the allergen is absorbed through the skin or breathed in causing an allergic response occur.
  • Certain breeds are more prone to atopy than others, but it can occur in any breed. There also seems to be a genetic predilection.

What Happens To The Dog When This Occurs?

Atopy in the dog is usually characterized by seasonal, generalized itching. Early on, many owners think their dogs’ behavior is normal, but as the disease progresses the signs become worse.
Atopic animals will usually rub, lick, chew, bite or scratch at their feet, muzzle, ears, armpits or groin. This can cause hair loss, redness and thickening and/or darkening of the skin. Saliva will often stain light-colored hair resulting in an orange or reddish-brown color. Some dogs (20 percent) will only show signs associated with chronic ear inflammation and infection.

How Do You Find The Cause Of My Dog’s Inhalant Allergy?

Diagnosis is not easy. It is based on the presence of clinical signs as well as ruling out other causes of itching such as flea allergies, food allergies, parasites or bacterial dermatitis. The itching caused by grass pollen looks the same as itching caused by house dust mites and many molds. In other words, your dog may be allergic to several different things with the end result being the same. 
A thorough medical history will help narrow the causes. For example, if the itching occurs in the spring when certain pollen is prevalent, this narrows the field of investigation.  It also will require some trial, error and patience.

When my dog’s allergies are bad, he/she seems to have a terrible smell. Is this normal?

When allergies occur, the skin produces more sebum, which is an oily material that causes a musty odor. Once the itching and scratching are controlled, the odor and seborrhea (dandruff) also clear up.
Another cause of odor is infection. Yeast and bacterial infections in the skin and ears can produce an unpleasant odor and are very common in animals with atopy.

Schedule An Appointment To Test Your Dog For Allergies!