Make your observations! What do you see first? What else can you spot in this photo?
Face: ears back, eyes squinty shut, eyebrows and forehead soft, panting with the corners of her lips pulled slightly back, tongue is not relaxed but is flopping out quite a bit
Head: raised and pointing the direction she's laying
Body: some tension in the single lifted paw/leg, but also laying on one hip rather than in the sphinx position
Context: green grass and seeding dandelions tells us this picture was taken in summer, while the dog being off leash suggests she had more freedom of movement
Please review the above body parts and compare with the photo to spot these cues yourself before reading further.
Background-
This photo was taken at the dog park, in the summer, in Las Vegas, NV. Penny had been playing quite a bit of fetch between greeting unfamiliar dogs.
Interpretation-
Due to the heat and exertion, it's reasonable to conclude that the panting with lips pulled back and a tense tongue in addition to Penny's ears being back, are due to her being overly warm, tired and potentially thirsty. But with more context, we don't have to assume! We can check the body tension in her movements, whether she avoids or approaches interesting things, if she startles easily or looks around frantically, plus any other body language reactions we can glean. In the follow up picture, we can see she's not particular tense, bracing or leaning and her tail is raised. These point further in the direction that she is not stressed or thirsty.