Some dogs can develop a urinary tract obstruction that physically blocks the flow of urine, or they may have a condition that affects lower urinary tract function.
Physical Obstructions
The most common physical cause of a dog not peeing normally is bladder stones that have moved into the urethra (the tube connecting the bladder to the exit). Not only are these painful, but they can interrupt urine flow. As mentioned earlier, this can lead to a total blockage, which is a medical emergency.
Other potential causes of obstruction in the urinary tract include anatomical abnormalities, such as:
Underlying Disease
Another potential cause of urinary issues is neurological disease, which can lead to a condition called neurogenic bladder. Additionally, some spinal diseases, like intervertebral disc disease, can cause dogs to lose control of their back legs. Dogs with longer backs, like dachshunds and shih tzus, are at higher risk of this condition, but it can happen in any breed.
When the connection between the brain and the back half of a dog's body is interrupted, they can lose control of their back legs and bladder. Some dogs may have more obvious symptoms, such as dragging their legs, walking on the tops of their feet or losing the ability to get up.
In addition to physical obstruction or loss of bladder control, another potential cause of a dog not peeing is the inability to produce urine. This can result from severe kidney failure or lack of access to water for an extended period.