Healthy dogs have transparent or slightly yellow urine without any traces of solid material like mucus, according to the American Kennel Club. Sick dogs may have mucus in the urine or dripping from the dog's body after he urinates.
The mucus is coming from the lining of the urinary system, which normally stays inside of the dog's body. During any infection of the dog's urinary tract, this mucus will be over produced and shed in the urine, according to "Dog Owner's Home Veterinary Handbook."
The body produces more mucus in an attempt to flush out the bacteria causing the infection. But this mucus can block the dog's urinary tract.
Other symptoms of canine cystitis or canine urinary tract infections are blood in the urine, the dog crying out when urinating, only being able to urinate a few drops despite straining and constantly licking the vulva or penis, according to "Dog Owner's Home Veterinary Handbook."
Mucus in a dog's urine should not be ignored. This can eventually lead to the formation of bladder stones, which can kill the dog, according to Vet Info.com.
The dog will first need a urinalysis and sometimes an x-ray to determine what kind of urinary tract infection he has and whether there are any stones. Then, antibiotics are given.