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Dog Allergies: From Itchy Skin to a Runny Nose, What’s Going On?
Spring is well underway, and as you may have already noticed, allergy season is also in full swing.
You may have appreciated this already in yourself with runny eyes and nose. But what about your dog? Does your pup usually get a runny nose and eyes too? Or does she instead get really itchy?
Dog allergies can be a little confusing. There are two categories of seasonal allergy presentations in dogs and they do differ a bit from what we may see with ourselves. This article will seek to explain some of those differences along with a veterinarian’s approach to addressing them.
What is an Allergy?
To know what allergies do, it’s important to first know what they are. Generally, an allergy is the response by the body to an allergen.
In many cases, an allergen is a protein, usually originating from a plant, animal, insect or food.
As the body is exposed to an allergen, like a plant pollen for example, over the course of months to even years, the immune system becomes hypersensitive to it. At some point, when presented with the allergen over time, the immune system may develop an unnecessarily severe response.
While allergens could be considered benign and harmless substances, the immune system will forever recognize certain ones as foreign invaders and cause an over-reactive response that can be harmful to the body.
This unnecessary immune response is what we see manifest as a stuffy nose, watery eyes, itchy red ears, feet, face, or even the entire body being itchy.
It is well-appreciated both in people and in pets that the severity of allergies can differ greatly in individuals and can have a large genetic component. Essentially, if you or your dog has more severe allergies than, say, friends at the dog park, the two of you may have programming in your DNA making you more susceptible to a severe allergy response.
This can be evidenced with certain breeds of dogs exhibiting more susceptibility to allergies in general. Examples coming to mind include Golden Retrievers, German Shepherd Dogs, Boxers, and American Pitbull Terriers, but include many others.
Dog Allergy Symptoms: Nasal Congestion and Watery Eyes
Inhaled allergens, which include offenders like pollens and mold that travel through the air, sometimes for miles, are the biggest source of seasonal allergy woes for both people and their furry counterparts.
When a pollen or mold spore gets inhaled and comes in contact with the lining of the nasal passage or the conjunctival tissues beneath the eyelids, the immune system checks it out and produces an antibody called immunoglobulin E or IgE.
Through a process called sensitization, which may occur over months to years, the body stores this specific IgE protein that was created, waiting to encounter the offending pollen or mold spore again.
At the same time, other immune cells including T and B lymphocytes, basophils, and mast cells convene around the pollen. They’re taught to recognize the villainous allergen and make it their job to dispel it.
Now, this may not happen early on during initial or early subsequent exposure to an allergen. Over time, the immune system primes itself to encounter that allergen and when it does, the response can be like a bomb going off, literally.
When the allergen comes along at a future time it will bind to the IgE antibody previously produced. The IgE antibody then seeks out other immune components, like mast cells and basophils. These cells literally rupture, releasing inflammatory particles like histamine.
Histamine, along with other inflammatory mediators, is what causes all of the redness and swelling. Dilation of blood vessels leads to congestion. Your eyes seek to dispel the allergens with excessive tears, while immune cells seek to remove the particles with lots of snot.
What Types of Therapies Help?
In this form of allergy, histamine is a bigger player, getting released from mast cells. Thus, use of antihistamines, like diphenhydramine (Benadryl), cetirizine (Zyrtec) or loratidine (Claritin) can help to reduce the severity of these types of symptoms. Make sure to ask your veterinarian what their preference may be and what dosage for each would be appropriate for your pet.
One important point here is to highlight the importance of NOT using any antihistamines that contain the decongestant pseudoephedrine. These products will have a “D” after the name (Benadryl-D, Zyrtec-D, etc.). Pseudoephedrine is toxic to pets as they cannot metabolize it like we humans can and is important to avoid. Make sure to just use the regular, plain over-the-counter form.
The antihistamine eye drops Zatador (ketotifen) can also be helpful to use in cases where the eyes are puffy and watery from allergies. These symptoms can be seen with many other eye disorders that may require other medications however, so make sure to check with your vet first before assuming allergies are responsible.
As with any type of congestion, a humidifier can help to loosen up the stuffiness. This is best used in a place your pet spends a lot of time, especially overnight in a particular bedroom, etc.
If you don’t have a humidifier, you can also simulate one for your dog by having her hang out in the bathroom while you take a shower. The warm steam from the shower for 10-15 minutes will help to relieve nasal congestion.
Although you can’t see them without a microscope, those pollens and molds can float around through the air very easily. Having an air purifier in your home that is capable of removing these offenders can be helpful. While you can’t do this outdoors, you may at least make things more pleasant for you and your pup indoors.
Dog Allergy Symptoms: My Dog is Scratching Himself to Death
While a stuffy nose and runny eyes is a common form of allergies for us, this form is actually in the minority for dogs.
What we generally see more commonly is an allergy manifesting as red, itchy skin. This may occur with the entire body, or may be focused only on one part, like the ears, the feet, or the muzzle.
When we see itchy skin in relation to allergens, this can be commonly called allergic dermatitis, or an allergic itchiness of the skin.
Allergic dermatitis can encompass a variety of allergens as causes. This may not only include environmental allergens like pollen and mold, but also fleas, mites, mosquitos and other insect bites, contact with an allergenic substance, and food.
Atopic dermatitis, also called atopy, is more specifically caused by environmental allergens that are either inhaled or come in direct contact with the skin. A dog food allergy, typically a food protein allergy and also called a cutaneous adverse food reaction (CAFR) is sometimes grouped as a part of atopic dermatitis.
Atopic dermatitis is considered to have a genetic component where a dog actually inherits the predisposition to have an over-reaction to IgE antibodies. Atopy may be seasonal or in some dogs, may occur year-round.
Unlike our stuffy nose and runny eyes, atopy is much more complex.
When an allergen attaches itself to the skin, a cell called an antigen presenting cell collects it for processing. It transports the allergen to a lymph node, where a cell called a T helper lymphocyte becomes involved.
What the T helper lymphocyte then does is what makes skin allergies in dogs so different and so frustrating to treat. It triggers other cells called cytokines. There are dozens of cytokines and they all carry a letter and number designation, like IL-31 for example.
These cytokines are involved with triggering the IgE to be produced. But they don’t just do that. Some of the cytokines, like IL-31, actually bind directly to nerves, triggering itch.
The scratching that ensues leads to further inflammation of the skin, more nerve conduction to the affected sites, and even the production of IgE antibodies against antigens the body itself produces that are released from skin cells traumatized by scratching!
How’s that for a cascade of complications?
But wait, there’s more.
This process is further complicated by many pets with atopy having inherited defects in the skin barrier. This allows more allergens to interfere with the skin. It also allows for microorganisms on the skin surface, like Staph bacteria and fungal yeast to overgrow with the inflammation and set up secondary infections. Secondary skin infections are extremely common in dogs with skin allergies.
While histamine may be released and mast cells are certainly involved to some extent, many researchers feel that what we have learned in the past 10-15 years about this complicated cascade of skin inflammation from allergens is still only a partial understanding of the full picture.
This process that occurs is very similar to the skin disease in people which is also called atopic dermatitis. As in dogs, people with atopic dermatitis also have a genetic predisposition to the disease.
What Types of Therapies Help?
Just like in people with atopic dermatitis, antihistamines appear to do very little to help dogs suffering from this form of skin allergy. This is thought to be because of how much more the itchiness is directly related to the cytokines interacting with nerves themselves in the skin.
Antihistamines may work some of the time, but figures have generously placed their effectiveness in the 25-30% range. One veterinary dermatologist whose continuing education seminar I attended said she believes even that small percentage may even just be due to the wishful thinking of hopeful pet parents.
Treatment for atopy, just like it is in people, typically involves glucocorticoid steroids and medications that modulate the over-reactive immune system’s activity.
This may involve topical medications like steroid creams or ointments, or may involve oral steroids. In pets, some newer allergy medicines for dogs have become available just within the past 5-10 years that help to block the activity of one or more of the cytokines themselves.
These medications have at least provided some options other than continuous use of steroids, which can have both significant short-term and long-term side effects, or broad-spectrum immunosuppressant medication.
While they are newer and more expensive, these newer medications do tend to work very quickly, often within hours to relieve an itchy dog.
It is also possible to have dog allergy testing performed, either through blood testing or through a process called intradermal skin testing. The results of allergy testing are then used to either help a patient avoid a particular allergen or to have something called immunotherapy developed.
Avoiding environmental allergens is often not possible, and so if a pet has a high sensitivity to some environmental allergens, a laboratory can use the results of allergy testing to create a series of injections or oral drops, collectively termed immunotherapy, that a dog can then take to desensitize her to the allergens.
The immunotherapy process can work very well, but often takes up to 6 months to be fully effective.
Fortunately, a majority of dogs may not need to go that far. The atopy may be seasonal, especially in spring/summer or in the fall, and so symptomatic therapy to treat flare-ups to get them through their season is common.
Since secondary infections, like bacterial or fungal overgrowth in the ears or on the feet, are so common, we’re often treating these with oral medication while also targeting the allergy response with a week or two of steroids or one of the newer medications aimed at blocking cytokines.
There are several natural ingredients that can help with skin and coat health, including grape seed, turmeric, quercetin, and omega-3 fatty acids.
Omega fatty acids are of particular note. While they can modulate some degree of inflammation, they most importantly support the skin’s health, allowing it to be a more effective barrier against allergens and the microorganisms that cause secondary infections.
Many dogs suffering from atopy and allergic dermatitis can benefit from having omega fatty acids included as part of their daily health regimen.
If you’re seeing allergies cropping up in your pup this spring or summer, hopefully it’s just for a short period.
While in people, the stuffy nose and runny eyes are extremely common, these signs are less common in dogs. They can however often be addressed with a good old humidifier at night and an antihistamine.
In dogs, skin allergies, or atopic dermatitis, is far more common. While atopy also occurs in people, it is far less common than sniffles and tears. Atopy is much more complex and usually requires a combination of other medications to address flare-ups.
Anytime your pup is showing signs of sniffling, sneezing, watery eyes, or itchy skin, it’s very important to have your vet take a look. It’s not safe to always assume your pet has allergies, as there are many conditions that can mimic what we see with dog allergies and can mean a very different treatment plan.