1-TDC means, 1-TetraDecanol Complex, which is the molecular name. 1TDC is a patented blend of fatty acid oils. 1-TDC is a proprietary blend of fatty acid oils from beef tallow derived from grass-fed animals. Extremely palatable, since it is derived from beef tallow. Pets see it as a treat...even cats 1TDC has an affinity for white blood cells, which makes it a more targeted and effective solution. Additionally, 1TDC is transdermal, which gives it the ability to effectively be absorbed and work locally. Even allergic patient to beef can use 1-TDC, allergies come from protein and 1TDC is a fatty acid. So, your pet should be safe.