The normal temperature can fluctuate during the day, so there is no point in taking 15 measurements: 2-3 taken during the day are enough.
Other factors can also influence the temperature: the state of stress (which can artificially raise the temperature a little), the support on which the animal is located (a cold tile will lower the normal body temperature), the physical activity or time-related variations (lower temperature in the morning and higher in the evening).
Before any handling, your animal must be as calm and confident as possible. Caress it, talk to it, get help if needed. Install yourself at height or on the ground.
To take the temperature of an animal, it is better to favor flexible and more reliable electronic thermometers. Avoid forehead thermometers (ineffective because of hair) or ear thermometers (temperature variation can also be attributed to ear disease).
Don't rely on the truffle to gauge your animal's temperature!