In the normal, day-to-day functioning of the body, lots of waste material is formed as a result of metabolic activity. It is the function of the urinary system to handle and to rid the body of these waste products.
In addition, through its ability to dilute or concentrate the urine, it serves to regulate fluid levels within the body.
Anatomy and Physiology
The urinary system of dogs and cats is composed of two kidneys, the ureters, a bladder, and a urethra. The kidneys are composed of cells called nephrons, which are responsible for filtering the waste material out of the blood and returning vital fluids and nutrients back into the bloodstream that would otherwise be lost in the urine.
Those solids and fluids not put back into the blood by the nephrons will eventually make up the urine. All the nephrons empty urine into a specific portion of the kidney, which then empties into the ureter for transport to and storage in the bladder.
The bladder wall is composed of smooth muscle and is capable of expanding to enormous sizes. Special muscular sphincters prevent the urine from passing out of the bladder prematurely.
Urinary incontinence, characterized by an inability to voluntarily hold urine within the bladder, can result from malfunction of these sphincters.
Once the bladder is ready to release its contents, the urine then passes out of the body by way of the urethra. Because of its vital function, any interference or alteration of urinary system function can quickly lead to serious health consequences.
For this reason, prompt and proper diagnosis of urinary tract disorders in dogs and cats is essential. Periodic checkups by a veterinarian can help detect potential problems before they reach such a magnitude as to threaten the health of the pet.