Seasonal skin allergies in dogs

Dogs that have seasonal allergies have red itchy skin. They scratch and nibble at their skin.

Where? 

Mainly in these areas: 

• Head (ears, around the eyes and on the muzzle);
• Groin, stomach and armpits;
• Tail;
• Elbows, heels and feet.

The inflammation and injuries that dogs cause to themselves cause these changes in the skin : 

• Hair loss;
• Égratignures and wounds;
• Lichenification (thickening of the skin);
• Hyperpigmentation (the skin becomes dark);
• Seborrhea (the skin is oily).

What else?  

Recurring bacterial or fungal infections (fungi). They appear as pimples, scabs and dandruff on the skin. These infections are present everywhere on the body, and particularly in the ears, between the toes and at the base of the claws.  

Dogs can also develop « hot spots », hives, boils (deep infection of the hair follicles) on the feet, buttocks and chin. 

When? 

Symptoms are present from spring to fall if the offending allergens are "seasonal" and inactivated by the cold (eg. pollen). The symptoms are apparent throughout the year if the offending allergens are not exposed to frost (eg. dust mites). 

Seasonal allergies generally affect dogs under the age of 3. Especially the following breeds :  

• Boston, Scottish and Cairn terriers
• Dalmatian
• English Bulldogs and Setter
• Golden and Labrador retrievers
• Irish setter
• Lhasa Apso
• Schnauzer
• Pug 
• West highland white terrier
• Wirehaired Fox terrier

Seasonal allergy is a skin condition characterized by inflammation and itching. It is also called « atopy ». It is caused by an abnormal response of the animal’s immune system to a substance in the environment (allergen). The disease affects genetically predisposed dogs. 

Here are some examples of common environmental allergens: 

• Dust mites (most frequent)
• Pollens
• Mold spores
• Dander
• Dust
• Grass

There are no laboratory tests available to determine if a dog suffers from seasonal allergies. We need to rely mainly on symptoms. Diagnosis can be difficult because the same symptoms are observed with many other illnesses and other types of allergies. In addition, an dog can suffer from several types of allergies simultaneously.

It is therefore necessary to proceed in a step by step fashion to get the diagnosis. We must: 

1. identify and eliminate parasites (fleas, sarcoptic mange, demodex, lice, cheleytiellosis); 
2. identify and treat secondary bacterial or fungal infections;
3. introduce an elimination diet trial to exclude the possibility of a food allergies.

A dog cannot be cured of his seasonal allergies, but his symptoms can be managed. With medication for short term control. With immunotherapy for long-term control.

Cortisone 

Cortisone is an antiinflammatory drug. At high doses, it has an immunosuppressive effect, which means that it reduces the activity of the immune system. It has the advantage of acting quickly, but it can cause bothersome and significant side effects. Especially when the dog consumes it over a long period of time.

Cyclosporine  

Cyclosporine is an immunosuppressant. It acts to its full potential after 2 to 4 weeks of treatment. It is generally well tolerated, but can still cause relatively significant side effects. It is safer than cortisone for long term use.

Oclacitinib 

Oclacitinib is primarily an antipruritic drug, meaning that it stops itching. It also has some anti-inflammatory effect . It works quickly, in less than 24 hours. It is very safe and causes very few side effects.

Lokivetmab 

Lokivetmab are antibodies. It attaches to the molecule that stimulates itchy nerve fibers in the skin. Thus, it prevents it from acting. This medication works quickly and is very safe to use. Its effect lasts a few weeks.

Antihistamines 

Antihistamines (eg Benadryl®) reduce or prevent histamine from causing itching. The effectiveness of this class of drugs is low when used alone. 

Desensitization with immunotherapy 

Immunotherapy involves administering increasing concentrations of the allergens that the dog reacts to. The goal is to get his immune system to develop a tolerance for these allergens so that it stops reacting to them.

An improvement in the symptoms is generally observed in 60-80% of dogs treated after 6 to 12 months. It can sometimes stop or decrease the amount of medication required to control symptoms.

Immunotherapy is safe, but expensive. In addition, it needs to be used for many months. This is why it is generally reserved for dogs who present symptoms more than 3 to 6 months per year.

Tests can be done to identify the environmental allergens to which a dog reacts , after concluding that he does have a seasonal allergy . The ultimate goal is to eliminate them from its environment. If this is not possible, we can at least know which ones to include in immunotherapy preparations .

Serological testing 

It consists in measuring the amount of antibodies against known allergens present in a sample of the dog’s blood. When this amount is high, we conclude that his immune system reacts to these allergens.

Intradermal testing 

This test involves injecting various known allergens on the surface of the dog's skin and observing whether or not redness appears. If that happens, then this indicates that the dog is allergic to it.

The tests' limitations 

Neither test is perfect, as is the case with most tests. There can be false positives and false negatives. On the one hand, several normal patients react to the allergens. On the other hand, the test can be negative if the allergens to which the dog reacts is not one of those tested.

Many dogs come to the vet because they are itchy. Seasonal allergies are one of the many causes of itching. To achieve adequate symptom control, it is essential to identify and treat other illnesses that cause the same symptoms.

Do you think your dog suffers from seasonal allergies? Call one of our establishments to fix an appointment and find out.

Text posted online on June 8, 2020.