Sublingual (oral) Immunotherapy (SLIT) vs. Subcutaneous (injection) Immunotherapy (SCIT)

Allergy injections given just beneath the skin, termed subcutaneous immunotherapy or SCIT is a common form of treatment of atopic allergy. It has been used for many years and is generally thought to provide symptomatic improvement in 70-75% of cases treated. While effective, SCIT presents some problems as shots are often times difficult to administer and some dogs don’t tolerate the physical trauma of injections.

These problems are eliminated with sublingual immunotherapy (SLIT), a technique by which allergenic extract is sprayed into the animal’s mouth. This USDA approved treatment delivers a measured amount of extract so dosage can be more accurately quantified.  The dose is delivered by inserting the dispenser spray nozzle into the side of the mouth between the gum and the cheek or under the tongue, and discharging a fine mist of allergenic extract.

As the immunologic mechanisms in the allergic response are studied they are becoming better understood. It appears that allergens deposited using SLIT are absorbed through the buccal mucosa. (inner lining of the cheeks and back of the lips). The misting effect of the spray enhances capture of the extract by the dendritic cells which move the allergens into the blood or lymph and circulate to various lymphoid organs where the antigens are presented to T lymphocytes. T-lymphocytes modulate overall changes to the immune system resulting in fewer allergic-like symptoms and suppression of other inflammatory reactions. The effectiveness of SLIT has been known for many years and is used for administering a variety of medications. (i.e., cardiovascular drugs, steroids, vitamins and minerals)

A growing body of evidence suggests that SLIT may become the treatment of choice for allergic immunotherapy treatment.

Data indicate:

  • Placing extract into the side of the mouth between the gum and the cheek or under the tongue is equally effective for treating a variety of allergic diseases.
  • Dispensing from a metered dose spray dispenser can be more effective than sublingual drops as allergen is introduced over a larger skin area. 
  • Treating is easier for both animal and owner. 
  • The smaller droplet sizes of the mist increases absorption rate.  
  • Animals may tolerate higher doses of allergenic extract using a mist applicator rather than a shot.
  • Animals may respond to SLIT (oral dosing) even though they may not have responded to SCIT (shot dosing).