The first question is not why. It is whether this is new.
Sudden and gradual are different problems
A dog who has been slowing down for weeks, lagging on the way home, taking longer to get going, is telling you something is building. That is usually joints, fitness, or age. Back leg weakness in older dogs covers that slower version, and it is a conversation with your vet rather than an emergency.
A dog who was walking normally ten minutes ago and is now planted on the sidewalk is a different situation. Something changed between then and now, and it is worth finding out what before you get them home and lose the evidence.
The two minutes before you do anything else
- Look at the feet. Pads split, a cut, grit or a grass seed between the toes, a torn nail. Check all four, including the one they are not favoring.
- Ask them to take a step. If they move, watch how. A head bob, a shortened stride, or a limb they will not load tells you more than standing still does.
- Run a hand down the neck and back. A dog who flinches, tenses, or holds themselves stiff and low may be dealing with neck or back pain rather than a leg.
- Check the ground and the air. Put the back of your hand flat on the sidewalk for seven seconds. If you cannot hold it there, neither can they.
- Look at their breathing. Heavy panting, drooling, wobbliness or bright red gums in warm weather is heat, and heat is an emergency.
Signs that mean today rather than tomorrow
Get to a vet the same day, or to an emergency clinic, if any of these are present:
- Will not put weight on a limb at all, or drags it
- Cried out, or cries when a particular area is touched
- Visible swelling, an odd angle, bleeding, or an obvious wound
- Sudden wobbliness, weakness in the back end, or knuckling over on a paw
- A stiff, hunched, guarded posture, especially with a lowered head
- Pale or very red gums, collapse, or labored breathing
- Any refusal to move that comes with vomiting or a swollen, tight abdomen
The back end and spine signs matter more than most owners expect. Intervertebral disc disease is genuinely painful and can leave a dog reluctant to move at all rather than obviously lame, and it is time sensitive. If the back end is unsteady rather than simply stopped, sudden hind leg wobbliness is the closer description.
When the ground is the whole story
Hot asphalt, salted or gritted sidewalks, and unfamiliar surfaces such as metal grates, glossy tile or a wobbling footbridge can make a dog stop. A frightening or uncomfortable experience at one surface may also lead to hesitation when the dog encounters it again.
If your dog stops in the same spot every time and walks normally everywhere else, you are looking at the location rather than the dog.
Fear looks like refusal too
Frightened dogs freeze. A dog who has planted with a tucked tail, a lowered body, ears back and a fixed stare at something specific is not being difficult, and the answer is distance rather than encouragement. In a newly adopted dog this is common enough to have its own guide: a rescue dog who freezes or refuses to walk on the lead.
What not to do
Do not haul on the leash. Dogs lean into pressure by reflex, so pulling forward usually produces a dog planting harder, and it puts load on a neck you have not yet ruled out as the problem. Do not scold a dog who has stopped. If the cause is pain or fear, you are adding to it, and if the cause is a grass seed you will feel terrible later.
Carrying a dog who cannot walk is reasonable. Supporting the chest and hindquarters together, rather than lifting under the belly, keeps the spine straighter on the way to the car.
If it keeps happening
Write down where, when, how warm it was, how far in, and which direction you were heading. A pattern of stopping only on the way out is a different story from stopping only on the way home, and either is more useful to a vet than telling them your dog has been odd on walks.