As an allergist, I’m frequently asked by my patients to discuss the topic of pet allergies. Since I’m a pet owner with allergies, I understand the dilemma when a patient comes to the realization they might be allergic to their furry friend. I have listed here some of the most frequently asked questions from my patients regarding allergies to pets.
How do I know if I’m truly allergic to my cat or dog?
Often the history is obvious for pet allergy: the individual was in good health until acquiring a new cat or dog. Sometimes symptom onset occurs immediately or within the first few days of the new exposure but for other patients it’s not so obvious. For some individuals, symptoms might have a gradual onset and take several months or longer before being noticed. Allergy skin or blood testing along with the history is how we as allergists confirm the responsible allergen.
What other animals can cause allergy symptoms?
We frequently see patients with allergies to other pets including horses, birds, guinea pigs, mice, ferrets, and even iguanas. The allergen responsible for horse allergy originates from the dander of the horse, bird allergen from the bird droppings, and rodent allergy from the pet’s urine. Ferret allergy is due to allergen from the dander and urine. Iguana allergy, albeit rare, is due to allergy to the iguana scales. Specific allergy testing can be performed to identify the culprit allergen.
What sort of symptoms would I expect if I’m allergic to our pet?
For patients with allergic rhinitis, one would expect any or all of the following: itchy, watery, stuffy nose and sneezing. Eye symptoms might include eyelid puffiness with itchy, watery, and red eyes. For asthmatics, symptoms could include chest tightness, cough, and wheeze. Skin allergies (urticaria or atopic dermatitis) might manifest as itchy skin associated with hives or eczema. Keep in mind you might have any combination of allergic symptoms mentioned here.
How can my symptoms be from my dog if it’s a hypoallergenic breed?
Unfortunately, there’s no such thing as a truly hypoallergenic breed. Dog allergen originates from the flaking dog skin dander and saliva. This dog allergen ultimately gets on the dog hair and if your dog sheds heavily, the dog allergen on the hair is transferred to the indoor flooring and furniture which in turn might cause symptoms. A non-shedding dog might be better tolerated by an allergic individual but depending on the severity of your dog allergies, there’s no guarantee you won’t become symptomatic.
Our pet is part of our family and we don’t want to get rid of it. What should we do?
This is a question I am constantly asked. Only under rare circumstances do I recommend rehoming the pet. Some relatively easy environmental changes, I suggest include: keeping your pet out of the bedroom with the door closed, acquiring air purifiers with HEPA filters for your bedroom and living area to reduce airborne pet allergens, eliminating carpet, and washing your hands thoroughly after touching your pet. In addition, having a nonallergic family member bathe the animal regularly might reduce the allergenic dander and saliva that transfers to the indoor environment. If environmental changes don’t sufficiently manage symptoms, medications are usually prescribed.
Which medications are effective?
Unfortunately, environmental changes alone might not be sufficient for controlling allergy symptoms. Assuming the individual’s specific history and physical exam is consistent with allergic rhinitis, we would likely recommend a nasal steroid-containing spray for daily administration and possibly a long-acting antihistamine either “as needed” or for daily usage. Prescription allergy eyedrops are often prescribed for those with eye symptoms. Patients with skin allergies might be prescribed antihistamines and/or steroidal creams, depending on the nature of skin involvement. For patients with asthma, we perform pulmonary function testing to grade the severity of lung involvement and tailor the medications to the individual patient.
Are there any options besides medications?
The previously mentioned environmental changes are extremely important and are recommended for all patients with dog or cat allergy. When environmental changes have already been implemented and improvement from medications have inadequately controlled symptoms, we often recommend immunotherapy. Immunotherapy, also called allergy shots, is a procedure where the patient is injected with gradually increasing doses of cat or dog allergen (or sometimes both) to induce immunity or tolerance. While immunotherapy might not completely eliminate symptoms for all patients, it can be expected to dramatically reduce the severity of symptoms and medications needed to control symptoms.
“When I went to the emergency room with my terrible case of hives, the emergency room doctor told me I must be allergic to something. Please tell me which food is causing my hives so I can stop eating it. What medicines can you give me to treat the itching that doesn’t make me so sleepy like Benadryl?”
We frequently see cases like this in our daily practice. This patient was very frustrated with having chronic hives, or chronic idiopathic/spontaneous urticaria for 3 months. We took an extensive history, asking about new medications that she may have started taking prior to the urticaria starting. We also asked about any insect sting that may have caused the hives to come out. Nothing in her history suggested any potential cause of the hives. During her visit we also did skin testing which showed she is not allergic to any foods. As I expected, she did not have any allergies: there was NO EXTERNAL cause to her urticaria or hives.
SO, WHAT IS CAUSING HER HIVES?
It’s important to know that there has been multiple studies reported in the literature regarding causes of urticaria presenting to an emergency room. The results are consistent. About one third of the time there is no allergic cause for the urticaria. It seems hard to believe, but it is true. The other two thirds of urticaria or hives caused by an allergy are a combination of food, insect stings, and medications (e.g. antibiotics or aspirin/Motrin type products).
We know that most ALLERGIC causes of hives result in the hives coming out within a few minutes to an hour of the exposure. For example, if someone is allergic to shrimp, they will break out within an hour (typically within minutes) of eating shrimp. One important exception is aspirin and ibuprofen type medications. These may cause hives that occur hours after taking the medication.
The bottom line is: NOT ALL HIVES ARE A SIGN OF ALLERGY TO AN EXTERNAL FACTOR such as a food.
Incidentally, many researchers are starting to refer to chronic idiopathic urticaria as chronic “spontaneous” urticaria. I agree with trying to change the terminology. “Spontaneous,” I think, is a better descriptive word of the problem (idiopathic is a medical term that means we don’t know what is causing the problem). In fact, we do know that chronic idiopathic/spontaneous urticaria is mainly caused by unstable histamine cells that reside in the skin. These unstable cells spontaneously burst open and release chemicals such as histamine that cause the hives and the severe itching.
HOW DO WE TREAT THIS TERRIBLE PROBLEM?
We usually are quite successful treating this problem with non-sedating antihistamines such as Claritin or Allegra, but using higher than the recommended dosages (under medical supervision, of course). Typically this works very well and doesn’t make the patient sleepy. Sometimes we have to add other medications such as H2 blockers (acid reflux medications that have antihistamine properties) and other anti-allergic type medications. When this is not successful, we will use a drug called Omalizumab. This is an injectable drug which is quite effective in controlling hives. In any case, the vast majority of our patients do very well in the treatment of the urticaria, with very little side effects of the medications. And the good news is that almost every patient will get a break from their urticaria after a few months. That is, most urticaria is not truly chronic – some people can go years between bouts of urticaria.
Dr. Neil Gershman MD
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