Hi Name,
To the human nose and eye there will always be differences in batch to batch of any essential oil.
It is a natural product. Conditions like rainfall, drought, amount of sun and age of the trees to name just a few will change the “Top Note” of the oil but not the biological composition.
Betula lenta commonly called “Sweet Birch” has wintergreen in it and the % of Wintergreen in Sweet birch will change how tingly and sweet is may seem.
K9NWSource buys Betula Lenta from one source in the US. It is organic and comes from the same orchard of Birch Trees year after year. It costs about 25-50% more than what most companies sell Sweet Birch for.
It is a not so well kept secret that there are not enough Birch trees in the world to produce the amount of Sweet Birch being sold. So some companies and blending in more Wintergreen into their Sweet Birch products. They will smell stronger. Still technically 100% Betula Lenta but an inferior product.
Take a small square of tin foil. Place a cotton ball that has 2-3 drops of the oil on it in the center. Crumple it loosely closed. Open it up in a few minutes and sniff. You will smell the oil more easily as it has had time to get into the air.
You dog should have no trouble finding hides with Q’s made as you have been doing with you previous oil. Replace your Sweet Birch every 2.5 to 3 years.