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12/12/12

Dog Neutering procedure

 Neutering procedure (desexing surgery) - a step by step pictorial guide to canine neutering.

As stated in the opening section, neutering is the surgical removal of a male dog's testicles. During the procedure, each of the dog's testes and testicular epididymi are removed along with sections of the dog's testicular blood vessels and spermatic ducts (vas deferens or ductus deferens). And to be quite honest, from a general, non-veterinary pet owner's perspective, this is probably all of the information that you really need to know about the surgical process of desexing a dog

Desexing basically converts this ...



This is a preoperative picture of a dog scrotum containing two testicles.

... into this ...

This is a photo of the same dog's scrotal sac after the testicles have been removedat surgery.

... by removing both of these.

Image: This is a picture of two canine testicles that have been removed by sterilisation surgery. You can clearly see the testis and epididymus of each testicle: these are the main sites of testosterone production and sperm production and sperm maturation in the male animal.


For those of you readers just dying to know how it is all done, the following section is a step by step guide to the surgical process of desexing a dog. There are numerous surgical desexing techniques available for use by veterinarians, however, I have chosen to demonstrate the very commonly-used "open procedure" of dog castration. Both diagrammatical and photographic images are provided to illustrate the process. 

STEP 1: Preparation of the animal prior to entering the vet clinic.


Preparation of an animal for any surgical procedure begins in the home. 

Your animal should be fasted (not fed any food) the night before a surgery so that he has no food in his stomach on the day of surgery. This is important because animals that receive a general anaesthetic may vomit if they have a full stomach of food and this could lead to potentially fatal complications. The pet could choke on the vomited food particles or inhale them into its lungs resulting in severe bronchoconstriction (a reaction of the airways towards irritant food particles, which results in them spasming and narrowing down in size such that the animal can not breathe) and even bacterial or chemical pneumonia (severe fluid and infection build-up within the air spaces of the lungs). 

The dog (or cat) should be fed a small meal the night before surgery (e.g. 6-8pm at night) and then not fed after this. Water should not be withheld - it is fine for your animal to drink water before admission into the vet clinic.

Any food that the animal fails to consume by bedtime should be taken away to prevent it from snacking throughout the night. 

Please note that certain animal species should not be fasted prior to surgery or, if they are fasted, not fasted for very long. For example, rabbits and guinea pigs are not generally fasted prior to surgery because they run the risk of potentially fatal intestinal paralysis (gut immotility) from the combined effects of not eating and receiving anaesthetic drugs. Ferrets have a rapid intestinal transit time (the time taken for food to go from the stomach to the colon) and are generally fasted for only 4 hours prior to surgery.

Young puppies and kittens (8-16 weeks) should not be fasted for more than 8 hours prior to surgery.

If you are going to want to bath your pet, do this before the surgery because you will not be able to bath him for 2 weeks immediately after the surgery (we don't want the stitches to get wet). Your vet will also thank you for giving him a nice clean animal to operate on. 

STEP 2: The animal is admitted into the veterinary clinic.

When an animal is admitted into a veterinary clinic for desexing surgery, a number of things will happen:

1) You should arrive at the vet clinic with your fasted pet in the morning. Vet clinics usually tell owners what time they should bring their pet in for surgical admission and it is important that you abide by these admission times and not be late. If you are going to be late, do at least ring your vet to let him know. Vet clinics need to plan their day around which pets arrive and do not arrive for surgery in the morning. A pet turning up late throws all of the day's planning out the window. Do remember that your vet has the right to refuse to admit your pet for surgery if you arrive late.

2) The animal will be examined by a veterinarian to ensure that he is healthy for surgery. His gum colour will be assessed, his heart and chest listened to and his temperature taken to ensure that he is fine to operate on. Some clinics will even take your pet's blood pressure. This pre-surgical examination is especially important if your pet is old (greater than 7-8 years).

3) You will be given the option of having a pre-anaesthetic blood panel done. This is a simple blood test that is often performed in-house by your vet to assess your pet's basic liver and kidney function. It may help your vet to detect underlying liver or kidney disease that might make it unsafe for your pet to have an anaesthetic procedure. Better to know that there is a problem before the pet has an anaesthetic than during one! Old dogs in particular should have a pre-anaesthetic blood panel performed (many clinics insist upon it), but cautious owners can elect to have young pets tested too. 

4) The dangers and risks of having a general anaesthetic procedure will be explained to you. Please remember that even though neutering is a "routine" surgery for most vet clinics, animals can still die from surgical and/or anaesthetic complications. Animals can have sudden, fatal allergic reactions to the drugs used by the vet; they can have an underlying disease that no-one is aware of, which makes them unsafe to operate on; they can vomit whilst under anaesthesia and choke and so on. Things happen (very rarely, but they do) and you need to be aware of this before signing an anaesthetic consent form.

5) You will be given a quote for the surgery. 

6) You will be asked to sign an anaesthetic consent form. As with human medicine, it is becoming more and more common these days for pet owners to sue vets for alleged malpractice. Vets today require clients to sign a consent form before any anaesthetic procedure is performed so that owners can not come back to them and say that they were not informed of the risks of anaesthesia, should there be an adverse event.

7) Make sure that you provide accurate contact details and leave your mobile phone on so that your vet can get in contact with you during the day! Vets may need to call owners if a complication occurs, if an extra procedure needs to be performed on the pet or if the pet has to stay in overnight.

8) Your pet will be admitted into surgery and you will be given a time to return and pick it up. It is often best if you ring the veterinary clinic before picking your pet up just in case it can not go home at the time expected (e.g. if surgery ran late).

STEP 3: The animal will receive a sedative premedication drug (premed) and, once sedated, it will be given a general anaesthetic and clipped and scrubbed for surgery.

The animal is normally given a premedication drug before surgery, which is designed to fulfill many purposes. The sedative calms the animal making it slip into anaesthesia more peacefully; the sedative often contains a pain relief drug (analgesic), which reduces pain during and after surgery and the sedative action results in lower amounts of anaesthetic drug being needed to keep the animal asleep. Depending upon the drug cocktail given, other specific effects may also be achieved including: reduction of saliva production and airway secretions (this reduces drooling and the risk that saliva and respiratory secretions may be inhaled into the lungs during surgery); improved blood pressure; airway dilation (making it easier to breathe) and so on. 

General anaesthesia is normally achieved by giving the pet an intravenous injection of an anaesthetic drug, which is then followed up with and maintained using an anaesthetic inhalational gas. The animal has a tube inserted down its throat during the surgery to facilitate the administration of the anaesthetic gas. 

The skin over the animal's groin, penis sheath (prepuce) and scrotum is shaved and scrubbed with antiseptic solution prior to surgery.

The surgery:

In order for you to properly understand the process of dog neutering surgery, I have to take a second to explain the anatomy of the male dog's reproductive structures (testicles, penis and so on).



 This image is a diagram of the reproductive anatomy of an entire male dog. The animal is drawn laying on its back as it would be positioned during a sterilization surgery. On the diagram, I have indicated the following structures: testicles (pink) contained within the animal's scrotal sac; bladder and urethral outflow tract (yellow); kidneys (brown); ureters (mauve); abdominal wall muscles (marked in dark red); vas deferens or ductus deferens (white); testicular blood vessels (red) and other male reproductive structures, such as the prostate and bulbourethral gland (a gland in the dog's penis that swells during copulation), both marked in orange. Notice how the ureter of the kidney loops around the vas deferens (spermatic duct) of the testicle - this occurs during early life when the testicle descends from the abdominal cavity and into the scrotal sac.



This diagram is a close-up view of the image contained above and is designed to highlight certain anatomical structures that are important considerations in this neutering surgery.

The first thing to notice is that each testicle is contained within a pouch of skin located just behind (caudal to) and slightly lateral to (alongside) the animal's penis. This pouch of skin is called the scrotum or scrotal sac. This is where the testicles will be taken from. 

The second thing to notice is that the spermatic ducts (vas deferens) and blood vessels supplying each of the testicles arise from within the animal's abdominal cavity. These vessels exit the animal's abdominal cavity in the region of the animal's groin, via a natural hole in each side (right and left) of the abdominal wall called the inguinal canal or inguinal ring (marked in purple). After exiting the abdominal cavity via the inguinal canal, these ducts and vessels run deep within the fat situated alongside the animal's penis and into the scrotum, where they unite with the sperm ducts and blood vessels within the animal's testicles. 

The third thing to remember is that some of the thick connective tissue lining the animal's abdominal cavity (the peritoneal lining - marked in green) actually comes out through the inguinal canal when the testicle descends during infancy and encases the testicle within the scrotal sac. The section of peritoneal lining containing the testicle within the scrotal sac and inguinal canal is termed the tunica vaginalis or vaginal tunic. On top of this, some of the abdominal fluid (lubricating fluid that exists in small amounts within the abdomen to let the organs slide over each other and not adhere to each other) and abdominal 'space' that exists within the abdominal cavity also goes with the peritoneal outpouching (tunica vaginalis) and into the scrotal sac and inguinal canal surrounding the testicular structures. This abdominal fluid and 'space' is marked in pale blue. It allows the testicular vessels and testicles to slide a bit within the scrotal sac and tunica vaginalis casing. 

The fourth thing you'll notice is that the urethra (outflow tract for urine) and penis of the dog runs underneath the skin in the region of the scrotum. This is important to remember during surgery.

STEP 4: The skin just in front of the scrotal sac is incised.



An incision is made into the skin just ahead of the animal's scrotal sac, on the midline of the animal. Both testicles will be removed through the one incision.

Caution needs to be taken to ensure that the urethra is not accidentally cut into during this incision. 

STEP 5: The testicle and tunica vaginalis is elevated through the hole in the skin.


Image: The first testicle is pushed forwards towards the hole in the animal's skin. The fat surrounding the testis and tunica vaginalis is trimmed away and the testis (enclosed within the thick, capsule-like tunica vaginalis) is lifted through the hole in the animal's skin. 

STEP 6: The tunica vaginalis is incised and the testicle exposed.


Image: The tunica vaginalis (green) is incised and the testicle itself (testis and epididymus) is exposed. Because the space between the tunica vaginalis and testicle contains small volumes of lubricating fluid (blue) from inside of the abdominal cavity, the testicle does not stick to the tunica vaginalis but instead slips easily out of it. 


STEP 7: The testicular blood vessels and sperm ducts are ligated (tied closed).


Image: Sutures are placed around the testicular blood vessels and spermatic cords. They are tied tightly to ensure that the blood vessels supplying the testes are fully occluded (closed off). This will prevent the animal's testicular blood vessels from bleeding once the testicle is cut off. These sutures are absorbable and so do not need removing later on. 


STEP 8: The testicle is removed.


The surgeon cuts off the testicle (testis and epididymus) above the level of the sutures and discards it. The first testicle has been removed. 

Author's note: Some surgeons like to also tie off the tunica vaginalis itself, instead of leaving it open. There are two main reasons for this. The first is that the tunica vaginalis has some blood supply of its own and oozes blood when you cut it. Although this seldom ever presents a significant, life-threatening bleeding issue, in large dogs this oozing of blood from the cut tunic can be enough to cause the scrotal sac to become swollen up with blood and therefore very painful and bruised after surgery. The second reason for tying off the tunic is that the open tunic does represent a theoretical open channel between the animal's skin/scrotum and abdominal cavity. Leaving the tunic open may potentially increase the risk of suture-line infections extending through into the abdominal cavity. There is also the potential (though it is rare) for abdominal contents to travel down the inguinal canal within the tunica vaginalis and end up under the skin, resulting in an inguinal hernia, which can be life threatening. 

STEP 9: Steps 5-8 are repeated for the opposite testicle.

STEP 10: The subcutaneous fat layers and skin are sutured closed (stitched shut).


Image: The skin wound is closed using sutures (stitches). The veterinarian will choose to use either superficial skin sutures (these are visible on the surface of the skin and need to be removed in 10-14 days) or intradermal sutures (these are located deep within the skin layer and do not need removal).


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