Urethral Stones - Urinary Obstruction

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Article Written by Dr. Daniel A. Degner, Board-certified Veterinary Surgeon (DACVS)

Animal Surgical Center of Michigan

5045 Miller Road

Flint, MI 48507

www.animalsurgicalcenter.com

Phone: 810-671-0088

Key Points

Urethral obstruction will prevent urination, therefore the bladder becomes very distended

This condition requires immediate medical and frequently surgical treatment

The prognosis is very good after the problem is corrected


anatomy of the urinary tractAnatomy

Urine produced by each kidney passes down a tube called the ureter to a reservoir, the bladder. The ureters have a thick muscular wall that propel urine to the kidneys in concerted waves of contraction. When the bladder becomes distended, urine passes out of the body via a tube, the urethra, during urination. In females, the urethra ends in the vagina and in males, the urethra terminates at the tip of the penis. A bone, called the os penis, is located in the penis in male dogs, which narrows the diameter of the urethra. As a result, even small stones can become lodged in the urethra at the level of the os penis. Female dogs do not have a bone surrounding the urethra, therefore small stones can pass through the urethra.

 

What is an urethral obstruction?

A stone may pass into the urethra from the bladder, thus cause obstruction to urinary flow. The result is that the dog cannot urinate. This problem is most commonly seen in male dogs due to the narrowing of the urethra at the os penis (see illustration below right and endoscopic photo of the urethra at the level of the os penis). Following obstruction to urinary flow, toxins build up in the body as urine cannot be excreted. Within 24 hours of obstruction, the dog will be very ill and can die.

 

Clinical signs

Warning signs of an urinary obstruction includes straining to urinate with no production of urine, dribbling small amounts of urine when trying to urinate, dripping blood from the penis, abdominal pain, depression and loss of appetite.

 

Diagnosis

Urethral obstruction is typically obvious on physical examination, as the bladder will be very large and urine cannot be expressed from the bladder. Radiographs (x-rays) are beneficial to determine the location of stones. If the stones are not visible on the radiographs, then a dye study may be needed. Blood work is always performed to see if the patient has a build up of toxins in the blood. Other causes of urethral obstruction may include urethral tumors, urethral granulomas, and urethral structures. Rarely, urethral obstruction is due to a surgical error made during castration (suture encircles the urethra). Below left is an endoscopic (telescopic camera) photo of the inside of the urethra, which shows two stones in the urethra. Below right is a photo of the normal narrowing of the urethra at the os penis.

 

Treatment

Patients that have a urethral obstruction need immediate treatment. Initial stabilization of the patient may be essential prior to surgery. Affected animals can be dehydrated, have an accumulation of acid in the body, have electrolyte abnormalities and toxin build-up in the body. Fluid therapy is essential to correct dehydration. If the patient is too sick to be anesthetized, then a temporary catheter may be placed through the abdominal wall and into the bladder to relieve the urinary obstruction. Typically within 12 to 24 hours, these patients are well enough to have general anesthesia and stone removal surgery.

Surgery typically involves flushing the stones back into the bladder with a catheter and saline. If this is not possible, then the stone may be retrieved with the assistance of an endoscope (telescopic camera) and specialized instruments. After the stones are in the bladder, they are removed via laparoscopic surgery or if the surgeon chooses, via an abdominal incision. The benefit of utilizing an endoscope to retrieve the stones is that this method greatly reduces the risk of incomplete removal of stones from the bladder or urethra (a number of studies have shown that veterinary surgeons leave stones in the bladder or urethra in about 20% of the cases when an endoscope is not used).

Sometimes stones can get lodged in the urethra at the level of the os penis and these stones cannot be removed. A scrotal urethrostomy is recommended in these cases and stones are also surgically removed from the bladder.

 

 

Potential complications

Even though rare, anesthetic death can occur. With the use of modern anesthetic protocols and extensive monitoring devices (blood pressure, EKG, pulse oxymetry, inspiratory and expiratory carbon dioxide levels, and respiration rate), the risk of problems with anesthesia is minimal. Recurrent bladder infections can occur due to infection ascending up the urethra. A urethral tear may occur during the process catheterization of the urethra (see photo below left and video below right showing a urethral tear; this one is small and will heal on its own). Stricture of the urethral tear site can occur if the urethra has been badly damaged or due to necrosis of the urethral wall from the lodged stones.

 

Straining to urinate may be a recurrent clinical sign and usually is due to a problem with the bladder (inflammation or infection) and not the urethra.

rev 10/2/11

Frequently Asked Questions After Surgery

When should my dog have the first bowel movement after surgery?

  • Many dogs will not have a bowel movement for the first 4 to 5 days after surgery
  • Reasons that a dog will not have regular bowel movements after surgery include:
    • The dog has been fasted prior to surgery
    • Dogs do not eat well during the hospital stay
    • They frequently do not eat well when they go home
    • They are fed highly digestible food that produces little stool
    • Pain medication that contain narcotics (such as morphine, fentanyl patches, and tramadol) can be constipating
  • If a pet does not have a bowel movement on the 5th day of being home, a stool softener such as metamucil can be fed
    • Dose of metamucil is 1 tsp per 25 Kg mixed in with each meal (canned dog food); feed immediately after mixing, as the metamucil will gel the food and may make it less palatable

My pet had surgery and will not eat.  What can be done?

  • Dogs
    • Most pets will not eat their regular dog food after surgery, especially if it is kibble.
    • Offer a cooked diet having a 1:1 ratio of a protein source and carbohydrate source.  The protein source can be any meat (example: chicken breast, turkey breast, lean hamburger) that is low in fat and should be cooked (drain off all fat after the meat has been cooked).   The carbohydrate can be pasta, potato or white rice.
    • Try canned dog food; to enhance the flavor sprinkle a very small amount of garlic powder or chicken or beef broth (Chicken-in-a- MugTM or Beef-in-a-MugTM products)
    • Try Gerber strained meats for babies such as the chicken, beef, turkey, or veal
    • Try Hill's A/D diet available at most veterinary hospitals
    • Hand feeding: place a small amount of food in the mouth so that your dog gets the flavor
    • Warm the food slightly in a microwave, as the food will be more aromatic; stir the food before feeding and test the temperature on the bottom side of your wrist; it should only be luke warm.
    • Remember that most pets will not eat the first day or two after they get home from surgery
  • Cats
    • Offer smelly foods that contain fish such as tuna or smelly cat foods
    • Try Gerber strained meats for babies such as the chicken, beef, turkey or veal
    • Hand feeding:  with your finger place a small amount of food on the roof of your cat's mouth; use a syringe to get soft food into the mouth
    • Warm the food slightly in a microwave as the food will be more aromatic; remember to stir the food before feeding and test the temperature; it should be only luke-warm
    • Some cats will only eat dry food, try kibble if your cat normally has been fed that food
    • Petting and stroking your cat frequently will help to stimulate appetite
    • Remember that most pets will not eat the first day or two after they get home from surgery
    • Appetite stimulants such as cyproheptadine may be helpful
    • If your cat refuses to eat anything for 7 days a stomach tube or nasogastric tube should be placed to provide nutrition so that a serious liver problem (hepatic lipidosis) does not develop

My pet is vomiting.  What can be done?

  • The first thing for you to discern is whether your pet is vomiting or regurgitating.  Both will result in fluid or food being brought up.  Vomiting always will have heaving or retching of the abdomen prior to expulsion of the vomitus.  Regurgitation is not associated with heaving and the pet usually just opens the mouth and fluid or food will be expelled.  Usually the regurgited material will be clear or brown colored fluid. 
  • Next is to identify the cause of the vomiting or regurgitation.
  • Causes and treatment of vomiting after surgery
    • When some pets return home after a stay in the hospital they may drink excessive amounts of water at one time and then vomit; if this appears to be the case, the water should be limited to frequent smaller amounts.
    • Medications such as antibiotics, narcotics or nonsteroidal anti-inflammatory medication commonly cause vomiting after surgery.  In order to see which medication is causing the problem, the administration of each drug should be separated 2 hours apart.  Usually the pet will vomit or appear nauseated (drooling and sick look) within 1 hour of administration of the medication that they are sensitive to.  The antibiotic in some cases may be changed to a different one, or may be discontinued. 
    • Stomach upset from anesthesia is a potential cause of vomiting and will pass within a couple of days. 
    • An uncommon cause of vomiting after surgery is internal organ failure.  Blood testing will confirm this problem. For this reason vomiting should not be ignored if it persists for more than 24 hours.
    • If your pet had surgery of the bowels or stomach, vomiting is always a concern, as it may indicate that infection of the abdominal cavity, called peritonitis, is present.  Do not ignore this sign.
    • Symptomatic treatment of vomiting involves withholding food for 12 to 24 hours, then introducing small amounts of bland food such as rice and lean cooked hamburger, if your pet does not vomit after that then gradually wean him/her back onto the regular diet after 3 days.  In order to decrease the acidity of the stomach, Pepcid AC 0.5 mg/kg can be given by mouth twice daily for 5 days.  Metoclopramide and Cerenia are good anti-vomiting medications for dogs and cats.  You should always consult a veterinary healthcare professional before administering medication.
  • Causes and treatment of regurgitation after surgery
    • The most common cause of regurgitation is reflux of acid from the stomach into the esophagus while your pet is under anesthesia.  Acidic fluid from the stomach can cause a chemical burn of the esophagus and result in a bad case of heart burn, called esophagitis.  This results in poor motility of the esophagus, therefore water and food will accumulate in this structure.  In most cases, esphagitis is self-eliminating and will resolve within two or three days. 
    • If the esophagitis is severe the esophagus may develop one or more strictures.  A stricture is a narrowing or stenosis of the esophagus and does not allow passage of food down the esophagus, in regurgitation that lasts longer than one week.  This problem should be brought to the attention of your pet's doctor within the first two weeks so that it can be treated by ballooning the stricture (minimally invasive procedure, as it is done with the aide of an endoscope).  If an esophageal stricture is chronic surgery is needed.
    • Symptomatic treatment of regurgitation caused by esophagitis includes feeding bland food, and administering a coating agent (sucralfate) and an acid blocker (omeprazole or other).  Consult a veterinary health care professional if the regurgitation continues for more than a couple of days.

How do I know that my dog is in pain following surgery?

  • Signs of pain include
    • crying
    • biting if you get near the surgical site
    • grimacing (lips are pulled back and the the dog looks anxious)
    • tragic facial expression
    • panting
    • restlessness and unable to sleep; pacing
    • if abdominal surgery was done the pet will not lie down on the incision, or will continually sit up in spite of appearing very tired
    • the worst pain will be for the first 2 to 3 days after surgery

What can I do to control my dog's pain?

  • Narcotic medications that control pain: tramadol, butorphanol, Duragesic (fentanyl patch)
  • Anti-inflammatories used to control pain: Deramaxx, Rimadyl, Previcox, or Etogesic
  • If an orthopedic surgery has been done cold packing the surgical site may be helpful
    • A cold pack may be a pack of frozen peas, crushed ice in a Ziploc bag, or a cold gel pack; place a thin barrier between the skin and the cold pack.  An alternative to a cold pack is to freeze water in a styrofoam cup; after frozen cut the bottom of the styrofoam cup out. Cool the surgical site around the incision by rubbing the exposed ice directly on the skin in a circular pattern.  Cooling the surgical site helps to numb the area.

How do I know that my cat is in pain following surgery?

  • Pain is more difficult to assess in cats versus dogs, as signs can be more subtle and they usually do not vocalize when in pain
  • Signs of pain in a cat include the following:
    • biting if you get near the surgical site
    • growling or deep cry
    • not wanting to eat
    • hiding and not wanting to be near owner (remember that this could also be caused by the cat just being upset about leaving home and coming back)

What can be done for pain at home for my cat?

  • Pain medication such as buprenorphine or a Duragesic (fentanyl) patch
  • Tylenol will kill a cat as they lack abundant glutathione enzyme in the liver
  • Anti-inflammatories can be used, but the dose is much less than dogs

Is it okay for my pet to lick the incision?

  • If a dog licks the incision, the healing process may be delayed.
  • Licking can remove stitches and cause the incision to open
  • Licking can become a severe habit that is difficult to break
  • Licking can cause infection as the mouth has many bacteria
  • Dogs will frequently lick the incision when the owner is not watching such as at night time; if the skin looks red or excoriated the most common cause is from licking.
  • To stop your pet from licking the following can be tried:
    • Elizabethan collar can be placed on the neck; this will not help stop your pet from scratching at the region
    • Cervical collar (bite not collar) is a less awkward device and can be effective at stopping a pet from licking the surgical site
    • A tee shirt can be used to cover an incision on the chest or front part of the abdomen; gather the waist of the shirt up over the dog's back and wrap an elastic band around this part of the shirt.
    • A bandage or sock can be used to cover an incision on a limb; fasten the top of the sock to the dog's limb with tape.
    • Bitter apple can be applied around the incision; many dogs will continue to lick  after application of this topical
    • Bitter Apple and Liquid HeetTM (obtain this from a drugstore...it is used for sore muscles) mixed in a 2:1 ratio can be applied around the skin incision
    • Antipsychotic medication in some cases is needed

Board-certification by the American College of Veterinary Surgeons

What does it mean?

  • Four years of advanced training in surgery beyond the Doctor of Veterinary Medicine Degree

  • Experience in the development of new surgical treatments

  • Rigorous examination by the American College of Veterinary Surgeons to ensure competency in advanced surgical techniques

  • Assurance that a veterinarian is a surgical specialist

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