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Understanding the Rise of Dog Allergies:
Why Are They Increasing

Posted by The San Francisco Dog Walker
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In the old days, dogs went to the vet for annual check-ups and that was it. Nowadays dogs spend a lot of time back and forth to the vet because of allergies - scratching, licking, skin hot spots and ear infections. Why is this happening?

Most often dogs will have one of two basic allergies: Flea or Food Allergies.

Flea allergies are usually relatively easy to solve in San Francisco because veterinarians offer a variety of highly effective choices. My experience has been that the fleas here are impervious to Frontline or Advantage. Most of my clients use oral meds - Comfortis or Trifexi, which are prescription only and they seem to work very well. October seems to be the month when the scratching is at its worst for those that are not on these prescription flea medications. The only problem is if your dog is exposed to ticks, these medications do not work. Only Frontline works for both fleas and ticks. But for fleas, not so well.

So your dog is itching like crazy and shaking his head constantly? AND it is not fleas? Your vet just told you it could be a food allergy. What does that mean? Anything from chronic ear inflammation, gastrointestinal problems, and chronic diarrhea to chronic gas, licking their feet, or an itchy rear end. Let's break it down:

What Are the Common Causes of Dog Allergies?

Allergies occur when a dog's immune system overreacts to a substance it perceives as harmful, even though it's not. The common triggers for dog allergies include:

Food Allergies

Some foods can trigger allergic reactions in dogs. Common culprits include:

If your dog has a food allergy, they may experience symptoms such as diarrhea, vomiting, or chronic ear infections.

Environmental Allergies

Environmental allergens can affect dogs just as much as humans. These include:

Dogs exposed to these allergens may develop seasonal allergies, which cause symptoms such as sneezing, watery eyes, and irritated skin.

Flea Allergy Dermatitis

Flea bites are a huge problem in San Francisco, especially during summer and fall, and for many dogs, the issue isn't just the bite—it's flea allergy dermatitis (FAD). Some dogs are hypersensitive to flea saliva, and a single flea bite can trigger an intense allergic reaction that lasts for weeks. This is why you might see a dog scratching frantically even after you've killed all visible fleas.

Our moderate San Francisco climate means fleas can be active year-round, but they're particularly prevalent in summer and fall when conditions are ideal for their reproduction. And here's what many dog owners don't realize: it's not just about the fleas themselves—it's about the allergic reactions they cause.

Signs of flea allergy dermatitis include:

Hot Spots: When Allergies Turn Serious

Hot spots, also called acute moist dermatitis, are one of the most common summer and fall problems I see in San Francisco dogs. These are raw, inflamed, oozing patches of skin that appear suddenly and can grow alarmingly fast—sometimes doubling in size within hours.

Hot spots typically develop when a dog's obsessive licking, biting, or scratching creates a break in the skin. The constant moisture from licking combined with bacteria creates a painful, infected area. Common triggers include:

Recognizing Hot Spots

Hot spots appear as circular, red, moist, and often hairless patches. They're usually quite painful, and your dog may cry out if you touch the area. The affected area will be warm to the touch (hence the name), and there's often a distinctive foul odor.

If you notice your dog suddenly obsessing over one spot—constant licking, biting, or scratching at the same location—check immediately. The faster you catch a hot spot, the easier it is to treat. Left untreated, they can become serious infections requiring antibiotics and sometimes even sedation for treatment.

San Francisco's Unique Allergy Challenges

Allergies are particularly problematic in San Francisco. Our year-round moderate temperatures mean allergens don't get the hard freeze that would kill them off in other climates. Plus, our fog and moisture can exacerbate skin conditions. Many San Francisco dogs suffer from:

What Are the Signs of Dog Allergies?

The first step to getting your dog's allergies under control is to learn how to spot the signs. Some common signs are:

If you see any of these signs, you should take your pet to the vet to get a correct evaluation.

How Are Dog Allergies Diagnosed?

Diagnosing allergies in dogs can be complex. Most likely, your vet will use a mix of techniques, such as:

Dog Allergy Treatments

A good dog allergy treatment depends on the type and severity of your dog's allergies. Here are some options:

Medications

Medications can provide quick relief from allergy symptoms. These include:

Topical Treatments

Shampoos, sprays, and creams can soothe irritated skin. For the best results, look for products containing oatmeal, aloe vera, or hydrocortisone.

Flea Prevention

Year-round flea prevention is non-negotiable for San Francisco dogs: Even one flea can trigger weeks of misery in an allergic dog. Don't skip monthly preventatives just because you don't see fleas—by the time you see them, the problem is already severe.

My experience has been that the fleas in San Francisco are impervious to Frontline or Advantage. Most of my clients use oral medications like Comfortis or Trifexis, which are prescription only and they seem to work very well. October seems to be the month when the scratching is at its worst for those that are not on these prescription flea medications.

The only problem is if your dog is exposed to ticks—these oral medications do not work on ticks. Only Frontline works for both fleas and ticks, but for fleas in San Francisco, not so well. Talk to your vet about the best prevention strategy for your dog's lifestyle.

Hot Spot and Allergy Management

The key to managing allergies and hot spots is aggressive prevention:

When to See the Vet for Hot Spots or Severe Allergies

Don't try to tough out allergies and hot spots at home. See your vet if:

Hot spots and severe allergies often require prescription medications—antibiotics, anti-inflammatories, or even allergy medications. The sooner you treat them, the less your dog suffers and the less expensive the treatment.

Dietary Changes

Switching to a safe or limited-ingredient diet can help a lot. Before making big changes to your pet's food, you should always talk to your vet. Remove suspected foods carefully and one at a time over a period of weeks, to see if there is any change in your dog's behavior.

How Can You Prevent Allergies in Dogs?

While it's impossible to prevent all allergies, these steps can minimize the risk and severity:

Are Allergies in Dogs Seasonal?

Many dog allergies are seasonal, especially those caused by environmental factors like pollen or grass. Symptoms often peak during spring and fall. If your dog's allergies are seasonal, your vet may recommend preemptive treatments during high-allergen periods.

Can Allergies in Dogs Be Cured?

Unfortunately, allergies in dogs cannot be cured. However, they can be managed effectively with a combination of treatments and lifestyle changes. Your dog can live a peaceful and happy life even though they have allergies if you take the right steps.

How Long Do Dog Allergies Last?

The duration of allergy symptoms depends on the cause. Seasonal allergies may only last a few weeks, while food allergies can persist until the offending ingredient is removed from the diet. Chronic allergies, such as those caused by dust mites, may require long-term management.

Is It Safe to Use Over-the-Counter Allergy Medications Designed for Humans?

Some over-the-counter medications, like antihistamines, can be safe for dogs when used under veterinary guidance. But you should always talk to your vet before giving your dog any medicine because the right amount and safety depend on the size and health of your pet.

Tips for Managing Dog Allergies at Home

In addition to veterinary care, you can take steps at home to keep your dog comfortable:

The Antibiotic Connection

Research shows that young animals treated with antibiotics could potentially be predisposed to problems later in life because antibiotics change the environment inside the gut, which is the largest immune organ in the body. That could be a predisposing cause, but then the trigger would be being exposed to the allergen. Was your dog given antibiotics as a pup?

A Food Recommendation from Experience

One of my clients has had very good luck using a food allergy dog food, which she purchased from her vet office, but you can get it online. It is called Nature's Variety INSTINCT Limited Ingredient Diet. It is Grain Free, Turkey Meal Formula Natural Dry Dog Food. It is raw nutrition and the dogs gobble it up like candy. It can be used as a treat, so you do not need to give them anything else for them to be happy and healthy. Give it a try! AND remember! Nothing Else! See what happens!

Conclusion

Dealing with dog allergies can be difficult, but knowing the reasons and signs is the first step to improving. You can take specific action if you know what causes your allergies—whether it is food, the surroundings, or fleas. Medicines, changes to your dog's food, and regular doggie baths can make a huge difference in his or her happiness and health.

Remember, allergies in dogs require ongoing attention and care. Working closely with your veterinarian and making small changes at home can help your furry friend live a happy, allergy-free life. If you suspect your dog has allergies, don't wait—seek professional advice to get started on the path to relief.