Atopy and Allergies in dogs

Spring sets in motion an onset of itchiness in dogs, especially for whom itchy skin conditions can cause great distress and discomfort. The cause of itchy skin (pruritis) can be varied and needs to be properly diagnosed by a veterinarian in order to determine the underlying cause and treat effectively.  Because of the spike in springtime itchiness in dogs, this blog explores causes of canine allergies, including atopic dermatitis. 

Common causes of itchy skin in dogs include
- Parasites (fleas, mites)

- Skin infections, ear infections

- Canine atopic dermatitis  (Atopy)

- Food allergy

- Contact allergy

- Very rarely, cancers can present with itchy skin.

What is an allergy?

An allergy is a damaging overreaction by the body’s immune system from exposure to a specific substance (an allergen), which the body has formed a hypersensitivity to over time. Most allergens are proteins; commonly from plants, insects, foods and animals. When exposure to allergens becomes too high, a dog’s immune response is triggered, leading to symptoms of allergy. There are many reasons and triggers for allergies in dogs. There can be confusion amongst pet owners that atopy is a seasonal allergy. This is a term used loosely as springtime sees a rise in airborne allergens and flare-ups can coincide. However, Atopy can initially present seasonally but progress to year-round.

What is Atopy
Atopy is an inherited condition. Also called atopic dermatitis, it’s a form of allergy, often airborne,  with an over-reaction occurring in parts of the dog’s body not in contact with the allergen. One of the telltale signs of Atopy is excessive itching. For these dogs, the outer layer of the skin (epidermis) is defective. Contact with allergens causes an inflammatory immune response which includes severe itchiness. 

Atopy is believed to affect 10-15% of the dog population (Cornell University). Dog breeds predisposed to developing atopy include;

Labrador Retrievers and Golden Retrievers, Weimaraners, Dalmatians. Soft-coated wheaten and wire-haired terriers; Scottish Terriers and West Highland White Terriers, Jack Russell Terriers. Boston Terriers. Bulldogs, Boxers, Staffordshire Bull Terriers. Lhasa Apso, Chinese Shar Pei and Shih Tzus are also susceptible, as are Chihuahuas, Bichon Frisé and other small white dog breeds. 

However, it is important to note that any dog breed, including mixed breed, can present with allergies.

Onset of atopy is generally between 6 months and 3 years old. It is most common in dogs where both parents were allergic (atopic), and there is no distinction between males or females developing this allergy.
 

Common allergens:
Common allergens can be either insect, plant or animal proteins, but some chemical molecules can also cause allergies. The most common allergens are;
- Pollens - grass pollens, tree pollens, weed pollens. 

- Mould spores/mildew

- Dust mites

- Insect proteins - such as flea saliva

- Shed skin cells (dander)

- And some medications.

Some common allergen grasses noted in the Southern Highlands include Buffalo grass and Kikuyu grass. Locally, trees such as Privet can trigger allergies in dogs and humans. Wandering Tradescantia is a weed used as an ornamental creeper in some gardens, it also is a common cause of allergy.

Privet

Wandering Tradescantia

Symptoms of atopic dermatitis include
Skin problems:
- Itchy skin (pruritis), either in one area or all over the body. The dog will try to relieve the itch by constant scratching, rubbing of their body on carpet, lawns and furniture, excessive licking - commonly of paws, or gnawing or chewing their skin, and bottom scooting.

- skin infections: broken skin/lesions from continual scratching and chewing. Continuous licking of inflamed hypersensitive allergic skin can cause secondary skin infections. This requires veterinary treatment, such as antibiotics, to treat the skin infection effectively, alongside treating the allergy.

- Hot spots - also called pyotraumatic dermatitis and acute moist dermatitis. Requires veterinary treatment.

- Changes in skin: darkening or thickening of the skin, darkening of hair from where the dog licks continually - such as paws. Red swollen skin, moist and odorous skin, and crusting on the skin are all signs that there may be allergic reactions occurring. 

- Hair loss: signs of allergy can include hair loss around the paws, for example, if there is a grass allergy.

Ear problems:

- Odorous, red, itchy ears 

- Persistent head shaking

- Pawing at ears, (as well as eyes and face)

- Recurring ear infections.

Respiratory problems:

- Runny nose. Excessive tearing and watery red eyes ( allergic conjunctivitis), and sneezing (allergic rhinitis)

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If you notice any of the above symptoms in your dog, please schedule an appointment with your veterinarian as soon as possible. It’s important to have a veterinarian diagnose allergies accurately in your pet and provide an effective treatment regime. Other conditions can present similarly to allergy, so it is crucial your veterinarian diagnose your pet first before embarking on any course of treatment on your pet.

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Insect bite reactions 

An insect bite or sting can cause exaggerated allergic inflammation in a pet.

The allergic reaction will be immediate, causing localised swelling in the area of the bite or sting. The swelling can be very distressing for a pet owner to witness. It’s important to contact your veterinarian should this occur, especially around any respiratory areas (nose, mouth, throat).

Insects that can cause allergic swelling include all arachnids (spiders and ticks), and insects that bite and sting such as fleas, mosquitoes, flies, bees, wasps, hornets and all types of ants.

Do antihistamines work?

Antihistamine therapy has been used in cases of insect bites and stings (see Cornell University). However antihistamines are found to be ineffective and not recommended in treating atopic dermatitis. Furthermore, it is dangerous and unethical to self-prescribe drugs, including antihistamines, on a pet who has not been diagnosed with allergy by a veterinarian. Itchiness causes in dogs can include, for example, staphylococcal infection, fungal infection, mites, even skin cancer. For these conditions antihistamines will be useless.

Treating atopic dermatitis effectively
Because atopy is inherited, the condition requires life-long management. It is difficult for a pet owner to hear a condition is incurable, but they can be managed successfully by owners through a prescribed, simple treatment regime. Atopy builds up over time and becomes worse year-on-year. Managing allergies from early-on, continuously, is important to ensure your dog isn’t suffering but has comfort and quality of life when allergy season returns, and you reduce the severity and frequency of the allergic flare-ups.

By the time a dog presents to their veterinarian, they may have been itching for some time and the allergic reaction has set in. The chances of an acute flare-up are higher and the skin may even be infected from constant itching.  The two forms of treatment tend to follow as 

1. Reactive therapy - treating the acute flare-up with veterinary care, and 

2. Proactive therapy - long-term preventative therapy, where owners can proactively help manage flare-ups.

Medications
Treating with medication can be very effective. These are prescribed by a veterinarian and must be managed with veterinary supervision to ensure safety and effectiveness against the allergy.  The therapy prescribed will be tailored to each individual dog depending on the severity of the allergy, and may be altered by their veterinarian as the condition changes throughout the dog’s life.

Topical therapy: 

Topical therapies are prescribed by a veterinarian and used at home on pets. They’re easy to use and are a critical part of ongoing maintenance to help curb the severity of flare-ups. 

They can contain antihistamines and corticosteroids to help reduce skin inflammation and relieve sensitive, allergic skin. They work by removing allergens from a dog’s coat whilst moisturising the skin. They can also help to treat secondary skin infections, such as bacterial and yeast infection. They include medicated shampoos, creams, mousses, medicated wipes, sprays.

Some effective topical treatments include: 

Barazone (mousse) is a prescription product. This mousse is a leave-on conditioner topical therapy for the symptomatic treatment of Canine Atopic Dermatitis, contact allergy and other pruritic skin conditions of the dog. Read more about this amazing mousse at https://dermcare.com.au/products/barazone/

Cortavance topical steroid spray: A prescription product. This is a hydrocortisone spray that topically treats inflamed and itchy skin.  Negligible absorption means it's safe to use on an atopic dog’s skin but always follows instructions on label after use. Excellent results are seen within 2 weeks to a month of use.

Read more about Cortavance here: https://www.ema.europa.eu/en/documents/overview/cortavance-epar-medicine-overview_en.pdf

Neocort cream is an antibiotic, anti-inflammatory and local anaesthetic topical cream. It’s a great all-rounder topical cream because it treats skin infections antibiotically, has topical anti-inflammatory ingredients as well as an anaesthetic effect to help ease excessive itchiness and pain associated with the flare-up. It is also safe to use long term on skin. A prescription product. You can read more about Neocort here; https://troylab.com.au/product/neocort/

Medicated shampoos are an OTC product.  It’s best if your vet helps you choose the right medicated shampoo for your dog’s condition. Shampoos we use include Malaseb & Pyohex. Read more about these medicated shampoos at https://dermcare.com.au/news/how-to-pick-the-right-shampoo/ 

We also recommend MediDerm, a low-irritant shampoo formulated using mild, effective active ingredients (including piroctone olamine) to aid in the treatment of canine skin infections and to remove scaly skin & grease.

Ear medications 

Otoflush® is an OTC ear flush. Designed to clean the ear canal of wax, exudate and debris, and reduce bacterial and yeast numbers in the dog’s ear. Also used as a pre-treatment flush. Your veterinarian may also prescribe medicated ear drops for your dog.

You can read more about Otoflush here: https://dermcare.com.au/products/otoflush/

Anti-inflammatory therapies:
These medications help reduce inflammation, and are especially helpful where there’s excessive itching and discomfort in the dog. They can bring quick onset, all-over relief to your allergic dog. Medications may include:
Corticosteroids (prednisolone) are injectable and tablet form. It can provide fast-acting short-term relief for your pet but is not recommended as a long-term therapy.

Apoquel (tablets & chewables) - a daily medication, with fewer side-effects than corticosteroids, relieves allergic itch within 4 hours and controls allergic itch within 24 hours. May be used both short and long term. Not suitable for puppies under 12 months of age. The active ingredient Oclacitinib inhibits enzymes involved in itch, inflammation, and allergic reactions (VCA Hospital). Read more about Apoquel here:

https://www.zoetispetcare.com/products/apoquel/itch-expose

Cytopoint (injection) A monoclonal antibody injected once a month or once every two months. A new science, Can be used longer-term. Works by acting like the dog’s immune system; it blocks a signal that triggers allergic itch. It is specifically designed to target and neutralize one of the main proteins that send itch signals to the dog’s brain, which triggers scratching, licking and chewing.

Read more about the science and benefits of Cytopoint here: https://www.zoetispetcare.com/products/cytopoint

Please note that Apoquel and Cytopoint are less effective in ear infections.

Antihistamines - ineffective in atopy, but may be useful in incidences of insect bite/sting allergic reaction.

Other therapies:

Nutritional therapy: Owners have found that Omega 3 /fish oil supplements can help support healthy skin function in their pet.

Desensitization therapy: Some clients wish to pursue a desensitization therapy route, or allergen-specific immunotherapy. It works to test, identify and reduce your dog’s allergic reaction through exposure therapy. Sometimes it is not possible to eliminate the allergen though due to its widespread presence in the environment. This therapy requires commitment in time and money by owners. It requires specialist referral to a veterinary dermatologist, followed by a minimum 6-8 week strict elimination regime. The efficacy of elimination diets is not always certain or high, so clients must weigh up the cost, time and possible success before making a commitment to this form of therapy route.

Very challenging allergy cases where it seems difficult to curb the allergic flare-ups may benefit from a referral to a veterinary dermatologist. In very rare cases, some cancers present as itchy allergic flare-ups. In these instances, your veterinarian may request pathology investigations.

Practical things pet owners can do at home
Many pet owners discontinue treatment once the skin looks ‘normal’ and their dog stops itching, until the condition recurs, and the flare-up cycle may begin again. A less acute flare-up (and better quality of life for your dog) is more likely if the condition is managed consistently at home. 

Flea + tick prevention; - keep up to date with high quality year-round flea and tick prevention; choosing reputable products ensures effective prevention against tick bites, mites, flea dermatitis and flea infestation, and mange. Flea dermatitis is a form of allergy in pets. Purchase your products at a pet shop or a veterinarian as they only stock reputable and effective brands.

Regularly wash your pet’s coat & their bedding - to cleanse from any pollen, irritants and soothe their skin. Monitor for allergic signs - constant licking, itchiness, red skin, smelly ears, and head shaking mean an allergic reaction may be occurring. As before, a medicated shampoo prescribed for allergic skin is good to soothe the skin and help prevent flare-ups or reactions from sensitive/hyper-allergic skin.

Modify your home and routine - avoid grassy walks/plays, and walk when the pollen count is low (midday). Consider if it's very windy not walking. If the grasses you have at home cause flare-ups, consider changing grasses or avoiding exposure of your pet to that lawn patch. Continue with medications or a change in diet, if prescribed by your veterinarian.

Continue with topical OTC therapy, if prescribed by your veterinarian -  this will help curb the frequency and severity of flare-ups and you may find dose rate can be reduced in time as well. Cortavance and Barazone are very effective spot-on topical therapies which have been found to help minimise itching before they spread.

Consider using a recovery cone on your dog, if they are having an itchy episode, using an Elizabethan collar/ e-cone can help the dog from making their skin worse by preventing excessive licking, until they have been able to gain relief with treatments.

Sometimes removing the allergen (if known) is the only way to minimize flare-ups.  This may include removing certain plants if that is what’s known to cause the allergen.  

If your dog has been diagnosed with atopic dermatitis, it’s not all bad news!

The condition can be successfully managed and treated by working as part of your pet’s health team alongside your veterinarian.

If your dog is experiencing some or all of the symptoms in this blog, call your veterinarian to make an appointment for an assessment.

Types of allergies in dogs
There are many types of allergies that can occur in dogs. The pet can develop concurrent allergies at the same time. For example, flea allergy and food allergy.  

1. Canine atopic dermatitis or atopy

Manifests in dogs with itchy (pruritic) skin. Dogs will show signs between the ages of one and three years of age, typically. It is managed with a combination of anti-inflammatory therapy, topical/bathing therapies,  and at home management/modifications.

2. Flea allergy dermatitis

Dogs allergic to the proteins in flea saliva will react with excessive itching and red inflamed skin when bitten by a flea. Parts of a dog’s body most commonly affected include the tail base, thighs and hind parts of the body. Management regime includes maintaining regular high quality parasite control in all pets in the home, as well as regular cleaning of the dog’s bedding, lounges, home carpets, etc. and treating your dog’s skin of any infections or irritation from allergy.

3. Food allergy

A hypersensitivity that develops to a meat protein or carbohydrate in food. Most common protein allergies are beef, chicken, eggs, soy and dairy products. Novel protein diets are often prescribed for these allergies (fish, kangaroo, crocodile, duck). However, an elimination diet under veterinary supervision is required for a correct diagnosis and treatment dietary plan.

4. Contact allergy

The most uncommon allergy involves direct contact with allergens such as grass, synthetic fibres in carpets or bedding, pesticides, pyrethrins etc., and develops into skin irritation and severe itching. Removing the allergen from the environment your pet is in will alleviate the allergy flare-ups. 

Sources and further reading:

- MSD Veterinary manual: Airborne Allergies (Atopy or Canine Atopic Dermatitis). https://www.msdvetmanual.com/dog-owners/skin-disorders-of-dogs/allergies-in-dogs  

- Cornell University, Cornell Richard P. Riney Canine Health Center: Atopic Dermatitis (atopy). https://www.vet.cornell.edu/

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Dreamstime Photo: https://www.dreamstime.com/
Veterinary Information Network   https://www.vin.com/vin/

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