The tail

Think of the tail as a mast. Held high and stiff often signals arousal or confidence, sometimes bordering on confrontational. Held at mid height, at roughly the dog's spine line, is usually relaxed and neutral. A low tail suggests uncertainty, sometimes appeasement. Tucked under the belly is a clear, "I feel small right now", usually fear or severe stress. Always read position against the breed baseline: a Husky naturally curls its tail high, a Greyhound naturally carries it low.

Loose, sweeping wags that move the whole rear end are the classic "I am delighted to see you" wag. Tight, fast wags where only the tail tip twitches can actually mean high arousal or tension. The rest of the body tells you which one you are looking at. Loose body plus sweeping wag equals friendly. Stiff body plus fast narrow wag equals, "something is up, stay alert". Neither wag on its own is a green light for strangers to reach in.

A line of research, starting with Quaranta and colleagues in 2007, found that dogs tend to wag more to the right side of their body when they feel something positive, such as seeing a beloved person, and more to the left side when they feel unsure or mildly negative. Other dogs in the room seem to notice and respond differently to each. You probably will not measure this in real life. It is still a fun reminder that tail movement is a full signal with sides, not just a simple on or off switch.

Tail shape and natural carriage vary wildly across breeds. A Pug's tight curl, a Labrador's otter tail, a Shiba's sickle tail, a Whippet's tucked-low carriage, all look different at rest. The trick is to compare the dog now to itself ten minutes ago. If a normally high-carrying breed suddenly drops its tail, that is a real signal. If a naturally low-carrying breed lifts its tail higher than usual, that is too. Always measure change from the individual's baseline.