______________ is the surgical procedure that utilizes extreme cold to destroy target tissues.

What is Cryosurgery?
 
Cryosurgery (or cryotherapy) is the application of extreme cold to destroy abnormal or diseased tissue. The term comes from the Greek "cryo" meaning icy cold and the word surgery meaning literally "hand work.”  Cryosurgery is used to treat a number of diseases and disorders, especially skin conditions. Cryotherapy may be a better description of the procedure, since surgery is usually associated with cutting and in most cases, this treatment (therapy) does not involve actual cutting. Cryotherapy has been in use for over two hundred years. The application of intense cold will result in the death of the targeted tissue and the numbing of surrounding sensory nerves, reducing pain and discomfort.
 
In humans, this technique is often used for the treatment of patients with intractable cancer, to reduce pain and discomfort by temporarily numbing sensory nerves. It is also used in humans to treat liver and prostate cancer, cervical cancer, and hemorrhoids along with a variety of skin conditions and tumors.
 
In animals, the technique is employed to treat tumors in locations where conventional surgery would be difficult or impossible, such as certain tumors of the mouth, or where the analgesic/anesthetic properties of the technique would be useful. Examples include the removal of highly irritant tumors or lesions which the animal is constantly biting, licking or scratching, tumors or infected itchy lesions in elderly patients considered high risk for general anesthesia, and prolonged surgical techniques where a long anesthetic may present unacceptable risks.
 
Depending on the size and location of the area to be frozen, your pet may or may not need to be tranquilized or anesthetized. Whenever possible on minor issues such as skin tags or small skin growths, we are able to perform this procedure in the office without any sedation needed. Due to the extreme cold temperature of the liquid nitrogen, the pet does not feel pain as the nerve endings are immediately frozen. This also means that as the dog or cat recovers and the unwanted tissue sloughs off, they still do not feel pain that may be associated with traditional surgery.
 
In addition to being less painful and in many cases safer than traditional surgery for your dog or cat, it also has some cost benefits for you! Prices for cryosurgery are often less than that of a regular surgical procedure, making this a win-win for both you and your pet!
 
How does cryotherapy work?
 
Cryotherapy uses freezing temperatures to destroy cells in the target tissues. Most of the body’s cells are comprised of about 70% water. When cells are subjected to freezing temperatures, ice crystals form inside the cells, causing them to tear and rupture. Additional cellular and tissue damage occurs when blood vessels supplying the diseased tissue freeze.  The intense cold also kills bacteria and other germs. This is particularly advantageous when dealing with infected tissues.
 
Once freezing has occurred, the tissue slowly dies and falls away. In some moist sites such as the mouth and the anus, the tissue may liquefy and look green and gangrenous. Usually all that is necessary is gentle bathing of the area to remove as much of the dead and sloughing tissue as necessary. There is sometimes a foul odor from the affected tissues. Despite the unpleasant appearance, there is little to no discomfort. The patient is usually much happier than before. In more advanced or serious conditions, multiple cryotherapy treatments may be required.
 
How is cryosurgery performed?
 
The most common method of performing cryosurgery is with liquid nitrogen. The super-cooled liquid nitrogen is sprayed on the diseased tissue, circulated through a tube called a cryoprobe, or simply dabbed on with a cotton or foam swab. Recent technologic advances include the development of ultra-thin 17 gauge cryoneedles, and the ability to use Argon gas to cause ice formation, using a principle known as the Joule-Thompson effect. This newer procedure gives doctors excellent control of the amount of tissue that is frozen and helps minimize complications.
The technique is sometimes also used for the removal of aberrant or extra eyelashes (distichiasis). This procedure has a high success rate.
 
Small warts and small skin tumors are usually cured with just one cryotherapy session.
 
How effective is cryosurgery?
In many cases, it can be curative depending on the condition and the site.
 
Contributors: Ernest Ward, DVM
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