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Environmental Allergies Versus Food Allergies in Dogs

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Environmental Allergies Versus Food Allergies in Dogs what the the main differences? Owning an allergic dog can be quite a frustrating ordeal and dog owners may want to find ways to alleviate their dogs' allergies. Is your dog suffering though from a food allergy or is the allergy to something in his environment? This is a very important question. Veterinarian Dr. Ivana discusses Environmental Allergies Versus Food Allergies in Dogs and points out their differences.

dog licking

Allergies in Dogs 

Constant scratching, tail-chasing, coughing, wheezing, eye and nose discharges – if your beloved canine baby exhibits these symptoms, chances are it is suffering from an allergy. Yes, dogs, just like their human masters, can suffer from allergies.

In fact, it is estimated that around 20 percent of all dogs suffer from some type of allergy. Allergies in dogs can be divided into two main categories:

1)Environmental allergies

2) Food allergies.

Let's take a closer look at both and then let's differentiate the two so to understand the main differences between environmental allergies and food allergies in dogs.

Environmental Allergies in Dogs 

Dogs can develop environmental allergy as a result of a plethora of environmental irritants. The most common culprits can be classified as: outdoor inhalant allergens, that is ragweed, pollens, grasses and indoor inhalant allergens –that is, molds, cigarette smoke, dust, mites and cleaning chemicals.

While we humans tend to exhibit environmental allergies through sneezing and coughing, dogs show their reactions through scratching and biting, as well as dog feet chewing and constant licking. A less common manifestation is recurrent ear infections.

Depending on the duration of the clinical signs, environmental allergies can be classified as: seasonal (usually associated with indoor allergens) and non-seasonal (usually associated with outdoor allergens).

The treatment involves two main steps – the first step is identifying the allergen, while the second step is eliminating the identified allergen. If the allergen cannot be identified or eliminated, the dog will need a lifelong treatment with corticosteroids and antihistamines. If possible, immunotherapy (treatment that uses certain parts of a person's immune system to fight diseases) may be the treatment of choice.

Corticosteroids are useful for controlling allergies because they reduce the inflammation in your dog’s skin. Although they tend to weaken the immune system a bit, in cases of allergies, they are considered to be the necessary evil. The most common side effects associated with corticosteroids are increased appetite, increased thirst and higher risk of developing infections. Therefore, corticosteroids are not recommended for long-term use. If a long-term use is unavoidable, make sure your dog’s blood and urine are regularly controlled by your trusted vet.

Prednisone is a short-acting steroid that can be used orally. It is considered to be safer than other long-acting steroids. If combined with antihistamines and Omega fatty acids as well as frequent bathing, this short-acting steroid can be used effectively in a lesser amount.

Desensitization or popularly known as immunotherapy is a special treatment, usually conducted by a veterinary dermatologist, that reprograms the dog’s immune system. First the dog’s skin and blood are tested to determine the exact allergens. Then, these substances are given to your dog in small, but increasing amounts via injections called desensitizing vaccines.

Over a period of time (generally at least one year), the dog becomes desensitized to the allergens and no longer exhibits allergic reactions to them. Desensitization is quite effective, but also quite expensive.

In general, statistics shows that 60 to 80 percent of dogs benefit from allergy shots, with younger dogs benefiting the most compared to older dogs. It's important to note that relief isn't felt right away. Allergy shots in dogs take weeks to months to work.

Last but not least, you can help alleviate your dog’s environmental allergy by vacuuming frequently and dusting the areas your dog spends much time in (like his sleeping area, crate, play zone).

Food Allergies in Dogs 

Generally speaking, dogs can be allergic to dog food or human food. The allergic response can be triggered by one particular ingredient or multiple ingredients. Common allergenic ingredients include chicken, beef, lamb, soy, wheat and dairy. Sometimes, dogs can be allergic not to the food’s ingredients, but to contaminants or substances used when the food is manufactured or packed.

Food allergies are usually manifested with vomiting, diarrhea, scratching, wheezing and sometimes, even changes in behavior. The diagnosis and treatment of food allergies include 2 phases: elimination and challenge.

An elimination phase is when a new diet is carefully selected to try to eliminate any foods containing allergens thought to be responsible for the food allergy. It is recommended that the elimination diet should be fed to the dog for 8 to 12 weeks.

The elimination diet trial is strongly suggestive of food allergy when the dog’s clinical signs resolve or improve by 50 to 75 percent without other ongoing medical support. On the other hand, if after 2 weeks there is no improvement, the dog does not have food allergy. There are a number of options for diets to be used during an elimination diet trial.

  • Hydrolyzed protein diet – hydrolyzed diets are theoretically "hypoallergenic: because their ingredients are chemically or enzymatically broken down into fragments that are so small that the immune system cannot recognize them.
  • Novel protein diet – first of all it is important to define the term novel protein. Is it lamb, horse, duck or eggs? Actually, it could be any of the above. "Novel" simply means new and different. In a nutshell, novel protein diets are foods that contain ingredients the specific dog has never been exposed to.
  • Home-prepared diets – homemade diets are often used as initial test diets for dogs with suspected food allergy because their composition can be more easily controlled. Homemade diets should be composed of just a few pure and simple ingredients. The food components often suggested for dogs are lamb, chicken, rabbit, venison, rice, potatoes and tofu.

During the elimination trial, it is vital that the owner fully understands that the dog can have no access to any other food item. This includes all treats, dental chews, rawhides, human food items, foods given to hide oral medications, flavored toothpaste, flavored toys and even flavored medications or supplements.

The return of clinical signs once the dog has been dietary challenged (by adding a new food ingredient to the menu) confirms the diagnosis. Additionally, challenging the dog with new ingredients is important in order to determine which ingredients are causing the food allergy. After the signs of food allergy or intolerance have resolved with the elimination test diet, specific food components should be reintroduced individually.

For example, if the dog’s allergy subsided on a diet of rabbit and quinoa, you can challenge the allergy by adding beef. Use the beef for at least two weeks. If there is no recurrence of allergy signs, you can continue by adding a new ingredient such as chicken. If the dog starts showing signs while fed with chicken, it is safe to assume that chicken is one of the triggers. After the symptoms caused by the chicken subside, you can introduce and test another ingredient.

This strategy should be continued until all of the offending ingredients are identified or at least until a well-balanced acceptable diet is achieved without any recurrence of food allergy or food intolerance signs. However, most owners are reluctant to alter a well-tolerated diet, once it is established.

Environmental Allergies Versus Food Allergies in Dogs

As seen, there are various differences between environmental allergies and food allergies in dogs.

Environmental allergies are allergies to things in the dog's environment and the most common culprits are outdoor inhalant allergens, such as ragweed, pollens, grasses, and indoor inhalant allergens such as molds, cigarette smoke, dust, mites and cleaning chemicals.

Food allergies, on the other hand, are allergies to one particular ingredient or multiple ingredients. Sometimes, dogs may be allergic to certain contaminants or substances used when the food is manufactured or packed.

Environmental allergies are known to cause scratching and biting, as well as dog paw chewing and constant licking. Some dogs may develop annoying, recurrent ear infections. Food allergies instead are known to cause vomiting, diarrhea, scratching, wheezing and sometimes, even changes in the dog's behavior.

Treatment options may also vary. Allergy shots for dogs (immunotherapy) for instance, don't work for dogs with food allergies. As mentioned, food allergies require a food trial. Allergy shots therefore may work for dogs with other types of allergies.

About the Author

Dr. Ivana Crnec is a graduate of the University Sv. Kliment Ohridski’s Faculty of Veterinary Medicine in Bitola, Republic of Macedonia.

ivana crnec

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