When we think of allergies, we imagine someone sneezing loudly, with streaming eyes and a runny nose. Allergies are not only a human phenomenon but an occurrence across mammals. There are different types of allergens, such as food, environmental such as pollen and, parasitic caused by fleas and mites.
Dogs are susceptible to the above, with environmental being the most prevalent. Dogs are affected by pollen, grass, trees and dust mites. Many owners are concerned when their pets start displaying behaviour such as self-harm, where they nibble and bite their paws to the point of hair loss and infection.
So how does this happen?
Dogs are very similar to humans in terms of their immune systems. They also produce antibodies, a protein created as a line of defence against foreign invaders such as viruses and bacteria. Antibodies such as IgE and IgG are found in high concentrations in blood allergy testing when an allergy is present.
Nearly every cell in the body presents an antigen, a protein that lies on the cell’s surface. Mammals have ‘self-antigens’ that the immune system normally does not attack because it chemically knows the difference between self and foreign invader.
Unfortunately, the antigens on pollen cells can trigger a full-blown immune response causing the release of these antibodies and histamine. Histamine is a triamine that induces vasodilation (the widening of blood vessels) and smooth muscle contractions in areas such as the lungs and uterus and can lower blood pressure. It can also trigger nausea due to the excess production of stomach acid. The increased permeability of the blood vessels allows white blood cells and proteins to assemble at the site of inflammation. Histamine causes the physical symptoms of an allergic reaction, such as coughing, sneezing, streaming eyes and laboured breathing.
Humans usually self-identify due to their symptoms when they have an allergic reaction and take an antihistamine to soothe them. Unfortunately, dogs must be diagnosed by a professional or owner through an elimination diet.
Signs of an allergic reaction in dogs
Food
Some dogs may experience diarrhoea or vomiting, or a dog may have more prevalent dermatological symptoms such as scratching and hair loss. Dogs with food allergies often nibble their paws and tail due to itching and discomfort. This can cause rust-coloured fur, such as in Bichon Frise and Maltese dogs.
Environmental
Environmental allergies can also take some time to be pinpointed by owners due to the cyclical nature of the seasons. They are characterised by coughing, sneezing, wheezing and runny eyes.
Parasitic
Parasitic allergies can usually be identified and treated without diagnostic testing.
Allergies from fleas and mites are the easiest to identify and treat due to the physical signs of infestation due to bites and dirt from the parasites. Severe allergy can cause ‘Flea Bite Dermatitis’ caused by the cocktail of proteins in the flea saliva. Symptoms include lesions, skin inflammation, hair loss and skin thickening.
Types of Allergy Testing
There are a couple of methods used to diagnose dog allergies. Tests such as the ‘Skin Prick’ or ‘Patch Test’ place a small amount of the allergen on the dog’s skin to observe if a reaction occurs. If an allergy is present, the skin will usually turn red, swell or come out in hives (urticaria). This is an accurate form of testing as the reaction is observed by the Vet or Vet Nurse, who will compile a list of allergens present, and the type of reaction followed, then usually provide medical advice for your pet.
Antihistamine tablets suitable for dogs are Loratadine, Cetirizine Hydrochloride and Clemastine, amongst others but do take care as some contain decongestants that can affect your dog. The dosage usually depends on the weight and is calculated by milligrams per kilogram (mg/kg).
The negative aspect of this type of test, although highly accurate – it is possible your dog will experience discomfort.
Blood Testing
A blood test works well if the dog has been exposed to the allergen and is experiencing symptoms. The test will confirm antibodies and can also test for high histamine levels. Specific allergy blood testing uses the ELISA method, Enzyme-Linked Immunosorbent Assay, where antibodies are linked to an enzyme and antigens from the allergen react to show a positive result. A colour change characterises a positive test. This type of test is highly accurate and is also used for pregnancy tests, amongst other things.
Bioresonance
This a non-invasive therapy but is currently considered a holistic test due to the lack of double-blind, controlled trials. It is proposed that cells within the body emit a specific frequency which gives information about what is happening on a cellular level. This information can then be used to identify, diagnose and treat conditions such as food allergies.
Saliva Testing
In 2018, a study, ‘Hair and saliva test fails to identify allergies in dogs’ (Coyner, K. and Schick, A. 2018), noted from testing and repeating their tests that saliva testing should not be used as a diagnostic tool. This is corroborated by further studies such as Udraite (Vovk, L. et al. 2019).
Elimination Diet
This process requires keen observation skills and consistency to identify possible food allergies. Poultry is common, so an owner could begin by removing poultry from the diet and observing symptoms. Apply this to different food groups. This can, however, take months to identify the root cause, but it is accurate.
Conclusion
There are many types of allergy testing to suit various needs. Several at-home dog allergy tests are also available to purchase, which can be used on uncomfortable or distressed pets who detest visiting the Vet. The most accurate tests with quick results are dermatological tests and blood tests.
References:
Anonymous (no date) Are over-the-counter medications safe for my dog: VCA Animal Hospital, Vca. Available at: https://vcahospitals.com/know-your-pet/are-over-the-counter-medications-safe-for-my-dog (Accessed: November 5, 2022).
Anonymous (no date) Blood testing for allergies, WebMD. WebMD. Available at: https://www.webmd.com/allergies/blood-test (Accessed: November 5, 2022).
Anonymous (no date) Food allergen testing, Food Allergen Testing | Microbac Laboratories. Available at: https://www.microbac.com/food-allergen-testing (Accessed: November 5, 2022).
Anonymous (no date) Histamine, Encyclopædia Britannica. Encyclopædia Britannica, inc. Available at: https://www.britannica.com/science/histamine (Accessed: November 5, 2022).
Anonymous (no date) Table: Antihistamine dosages, MSD Veterinary Manual. Available at: https://www.msdvetmanual.com/multimedia/table/antihistamine-dosages (Accessed: November 5, 2022).
Coyner, K. and Schick, A. (2018) “Hair and saliva test fails to identify allergies in dogs,” Journal of Small Animal Practice, 60(2), pp. 121–125. Available at: https://doi.org/10.1111/jsap.12952.
Nohr, M. (2022) What is the best food sensitivity testing method?, DrJockers.com. Available at: https://drjockers.com/food-sensitivity-testing/ (Accessed: November 5, 2022).
Udraite Vovk, L. et al. (2019) “Testing for food-specific antibodies in saliva and blood of food allergic and Healthy Dogs,” The Veterinary Journal, 245, pp. 1–6. Available at: https://doi.org/10.1016/j.tvjl.2018.12.014.
