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12/12/12

Dog : Possible surgical and post-surgical complications of neutering

Possible surgical and post-surgical complications of neutering

There are some surgical and post surgical complications of desexing a dog that should be considered before you take the step of having your pet neutered. These are outlined below. The most important thing to remember about the complications listed below is that the vast majority of these complications are very rare and the small risk of them occurring should not outweigh the benefits of having your pet neutered. Of those complications that are more common (the common ones are indicated), the vast majority of these are not life-threatening and most can be prevented by good attention to after-care and wound care. 

Pain after surgery (common).

It is not uncommon for dogs to show some signs of mild to moderate discomfort and pain immediately after having a desexing surgery. It stands to reason: the vet has just performed a surgical procedure on a very delicate area of the male body. 

Dogs that are in discomfort after desexing will normally show signs suggestive of pain in the groin region. The animal may pant a lot; pace the room (not want to settle);adopt a stiff hind leg gait (these animals are reluctant to move their hind legs much when walking) and refuse to sit down in a normal sitting posture. Some dogs will be irritated by the sutures and/or by the fact that the delicate scrotal skin was shaved (and thus abraded a little) and keep licking the region obsessively (this licking needs to be discouraged by placing an Elizabethan Collar on the dog or a bitterant on the wound - see section 5 on aftercare). Some dogs will even go off their food for a few days after desexing because of the discomfort. 


If your pet is in pain, you can return to your veterinary clinic for some analgesic (pain killer) pills. Most vets send their neutering patients home with a few days of pain relief as a matter of course, however, some vet clinics do not. If you haven't been sent home with any pain relief for your pet and your pet shows signs of pain after surgery, you can return to your vet clinic and request pain relief pills - these will normally be enough to keep your pet comfortable. If your pet is very old or it has compromised kidney or liver function, certain pain medications may not be recommended and other pain relief solutions may need to be found.

Keep your pet confined and quiet if it is in pain. Pets that are allowed to run around after surgery are more likely to traumatise and move their sutures, leading to swelling and pain of the surgical site. Reducing activity means less pain.

Consider placing hot and cold compresses (nothing that will wet the site however) on your pet's surgical site to reduce pain and swelling. Placing an ice pack wrapped in a tea towel (never put ice directly against the skin) on the pet's surgery site for 10 minutes and then placing a hot water bottle (also wrapped in a tea towel) on the site for another 10 minutes and then replacing the cold pack and so on (i.e. alternating hot and cold packs) can go a ways towards reducing surgery site pain. Do this for around 30-45 minutes. 
WARNING - Only do this if you have a very nice tempered dog - remember that pets in pain can bite and you may well upset the animal more by handling his wound, even though you are only trying to help him. 

If the scrotal skin appears very abraded and red to you (either from clipper rash during pre-surgical shaving of fur or due to your pet's licking), you should speak to your vet about it. He may prescribe some cream containing a steroidal anti-inflammatory drug, an antibiotic compound and a local anaesthetic (e.g. tradenames include Ilium Neocort Cream, Neotopic Cream) to apply to the abraded regions to soothe them. Do not apply the cream directly to the surgical wound.

If your pet's discomfort lasts more than about 1-3 days after surgery, you should seek advice from your vet. Most pets don't show signs of surgical discomfort beyond about 3 days and pain persisting beyond this point may be a sign of wound infection, suture-line reaction or some other issue.

 Swollen, bruised, blood-filled scrotum after desexing surgery (common).

It is not uncommon for dogs to go home from sterilisation surgery with a very swollen, bruised-looking, blood-filled scrotum. 

The condition is more commonly seen in large breed dogs that have been desexed and in males that have been neutered as adults later in life (basically, these animals have larger blood vessels in their scrotal pouches and vaginal tunics, which are more prone to heavy bleeding when incised). From a clinical viewpoint, I have most commonly encountered the condition when the same large breed or adult dogs are neutered and their tunica vaginalis (see section 4, STEP 8, on dog desexing techniques) is not ligated (tied off).
Author's note - I do tie off the incised tunica vaginalis once the testicle has been removed and have to say that I have not personally had a lot of dogs coming back with giant, blood-filled scrotal sacs.

From a post-operative perspective, bleeding into and swelling of the scrotal sac may also occur if a pet is allowed to run around too much (excessive exercise and rough-and-tumble) or lick its surgery site excessively in the hours to days after surgery. 

Rarely, a blood filled scrotal sac may be an indication that the animal in question has a bleeding disorder, which needs to be worked up. It is not uncommon for vets to diagnose a medical blood clotting condition such as vwD (von Willebrand's Disease) in a Dobermann Pinscher because its surgical site will not stop bleeding. Similarly, other severe bleeding disorders like rodenticide poisoning (rat bait poisoning), platelet deficiency, hemophilia and so on may occasionally be found by accident during surgery because the animal won't stop bleeding during surgery or the scrotal sac fills with blood afterwards. 

When hemorrhage into the scrotal sac occurs, the signs are normally pretty evident. The animal will develop a swollen, enlarged scrotal sac, which may appear very red and bruised-looking in appearance. Some owners even ring their vet accusing him or her of not desexing their dog because the large, blood-swollen scrotum sac looks the same size as it did when it contained testes. Animals with swollen testicle sacs will often exhibit signs of pain: they may pant a lot; pace the room (not want to settle); walk stiffly with their hind legs and refuse to sit down in a normal sitting posture. Some will lick the swollen region obsessively, which only increases the scrotal trauma and swelling. 

Generally, blood-filled, swollen scrotal sacs will resolve and shrink on their own as the blood is reabsorbed back into the body. They do not normally require any specific treatment. You can manage the animal's discomfort by giving it canine pain killers, restricting exercise, preventing licking and pacing hot and cold compresses on the scrotum. In severe cases, your vet may insert a needle into the swollen sac to remove some of the blood and relieve some of the pressure and pain, however, this is seldom necessary and does run the risk of introducing bacteria into a sterile site and setting up an abscess. 

Wound break-down - break down of the sutures or stitches (moderately common).

It is possible for the neutering incision site to break down days to weeks after desexing, leaving an open, rotten-looking, fleshy hole in the base of the penis sheath. Wound break-down most commonly occurs because of poor home care. It tends to occur because the pet was permitted to lick the sutureline and/or pull the sutures out or because the animal was permitted to run around a lot (exercised). In some cases, the wound breaks down because of bacterial infection (wounds can not heal if they infected) and, again, this is often the result of poor home care, not poor surgical technique. Infection tends to occur if the sutures are allowed to get wet (the animal is bathed, allowed to go swimming or allowed to lick the wound excessively) or if the sutures are allowed to become soiled by faeces, urine or dirt. 

Very occasionally, wound break-down can be a result of poor surgical technique (the sutures were not placed correctly or the wrong sutures were used); performing surgery on infected or diseased skin (animals should not be operated on if they have allergic, rashy or highly-infected skin) or removing the sutures too early (before the skin has had time to heal). Some cases of wound break-down may even be the end result of suture-site inflammatory reactions (see section 6e). 

Very rarely, wound breakdown may also be a sign that the animal in question has some form of healing disorder. Such disorders are uncommon, but do exist. For example, animals with Cushing's Disease (Hyperadrenocorticism) may be prone to slower-healing wounds and their sutures may need to be left in longer than usual (taking them out too early may result in wound break down). Animals with collagen disorders (e.g. Erhlos Danlos Syndrome in cats), inflammation-response disorders and other disorders affecting tissue healing function may also heal very poorly and be prone to wound break-down. 

Wound breakdown is cause to see your vet. If the wound break down is only mild, the animal may only require antibiotic coverage; an Elizabethan collar and better home care to treat the problem. If the wound has completely fallen apart, the vet may need to operate on your pet again to retrim and repair the surgical wound. Healing will then take another full 10-14 days to occur. 

 Wound infection (moderately common).

The causes of wound infection bear many similarities to those mentioned in section 6c and infection of surgical incision-sites can often lead to secondary wound break-down.

Wound infection occurs when bacterial organisms gain access to the surgical incision site and multiply there in large numbers. The bacterial invasion causes damage to the body tissues in the site of infection (this limits healing of tissues) and triggers a secondary immune system attack on the region, resulting in inflammation and a build up of pus (invading white blood cells produce yellow or green discharges) in the area.

Owners often first notice infection when the neutering incision line becomes sore, swollen, red and hot-to-touch. Sometimes, the pet will tell the owner that it is in pain by licking the infected regions obsessively: infection should certainly be suspected if a pet goes from not being bothered by its wounds to licking and biting at them excessively. Within hours to days of this redness and inflammation being noticed, the owner may witness a yellow to green purulent discharge coming from the suture holes or the incision line itself. If allowed the progress, the wound may split apart completely, resulting in wound breakdown. 

Wound infection is very uncommon in most routine desexing surgeries and most commonly occurs because of poor home care. It tends to occur because the pet was allowed to lick the sutureline and, consequently, introduce mouth bacteria into its surgical incision. Infection also tends to occur if the sutures are allowed to get wet (the animal was bathed, allowed to go swimming, allowed to lay in mud) or if the sutures are allowed to become soiled by faeces, urine or dirt. Wound infection may also occur if the vet performs the surgery on an animal with diseased allergic or infected scrotal/groin skin. Bacterial numbers are very high in diseased skin and will easily enter the wound site during surgery, regardless of the amount of prepping done. 

Very occasionally, wound infection may be a result of poor surgical technique (e.g. vets not wearing gloves to do surgery); poor skin preparation technique before surgery; a freak bug entering the surgical site (sometimes nasty bacteria like Golden Staph and flesh-eatingStreptococcus and Mycobacteria species will find their way into a vet clinic and cause havoc) or the animal having a poor or compromised immune system. Animals with Cushing's disease, Diabetes Mellitus and other immune suppressive disorders may be more prone to wound infections. 

Wound infection is definitely cause to see your vet. If the wound infection is only mild, the animal may only require antibiotic coverage; an Elizabethan collar and better home care to treat the problem. If the wound has completely abscessated and is at risk of falling apart, the vet may need to operate on your pet again to retrim and repair and clean the surgical wound. Healing will then take another full 10-14 days to occur. 

Suture-site reactions - swollen, red skin around the suture holes (not too common).

Suture site reactions refer to allergic-type skin reactions that some dogs and other animals develop because of the type of suture being used in the surgical incision repair. Basically, suture site reactions are immune-mediated inflammatory reactions that occur when the dog's body decides to reject the foreign bodies (the sutures or stitches) that the vet has just implanted into the skin. True suture site reactions are not that common (modern day sutures are normally very inert and non-reactive) and most so-called suture site reactions are actually wound infections or break-downs caused by all of the factors mentioned in sections 6c and 6d. 

When suture site reactions do occur, what tends to happen is that the animal develops signs of inflammation (redness, swelling, heat, maybe even a serous (watery) or pussy discharge) around the suture holes themselves, but not along the surgical incision line in general.
i.e. The reaction is centred around the sutures, but the rest of the surgery site appears fine.

Author's note - early bacterial infections can mimic suture-line reactions if the bacteria have gained access to the body tissues by traveling up the sutures. In these cases, the inflammatory reaction will also be centred around the sutures because this is where the bugs are lurking. Untreated, however, bacterial infections will be expected to spread and become more generalized (i.e. all of the incision line), whereas true suture-line reactions should remain localized and focussed upon the stitches.

Usually what happens with suture site reactions is that the wound incision itself heals up fine because the reaction is centred around the sutures only. Once the sutures are removed (usually after the surgical site has healed), the problem usually resolves on its own. If the condition is severe and the wound healing itself is becoming secondarily compromised by the suture reaction, the vet may elect to remove the skin sutures early to let everything settle down again and heal. This does, however, pose a risk of the main wound breaking down prematurely. In most cases, especially mild cases, the vet will elect to leave in the sutures until the main wound has healed and then remove the sutures to let the suture reaction resolve. 

To prevent the problem in the future, a different type of suture material should be selected.

Penis and/or urethra laceration (very rare).

In the diagram image opposite, you can see that the penis (pale pink) and urethra (urine outflow tract - indicated in pale yellow) run deep under the skin, just beneath the site where the first neutering skin incision is made. It is, therefore, theoretically possible (very rare) for a careless or inexperienced surgeon to slice into the animal's penis and/or urethra if he or she cuts too deeply. 

If this occurred, a very severe, costly and potentially life-threatening situation would result. 

If the penis was cut, the animal would suffer from extreme penile bruising and hemorrhage (the penis is extremely vascular with massive blood chambers and vessels inside of its fleshy wall). Bleeding could be so severe that the animal might require a blood transfusion and intravenous fluid support to save it. It is also possible that the animal could potentially lose the end of its penis as a result of loss of blood supply to the end of the penis and tissue death. Reconstructive surgery would then be required to remove the necrotic (dead) penis and refashion it so that the animal was able to pass urine. 

Rupture of the urethra would result in all of the severe bleeding and other potential complications described above for penis laceration because the penis would have to be cut in order for the urethra to be lacerated (the urethra runs inside of the penis and can not be cut without the penis also being cut). The animal would suffer bleeding into the urethral tract (it would urinate blood-filled urine). If repair was not carried out promptly and correctly, urine would start to leak from the torn urethra into the fat and skin of the surgical site. This urine is very acidic and irritant and leakage of urine under the skin would result in severe tissue swelling, pain and inflammation. It is very likely that much of the fat and tissues exposed to the urine would break down and rot along with the skin suture site itself, resulting in a nasty, open surgical neutering wound through which urine and inflammatory fluids would ooze. Such an animal would be expected to be very unwell (would need 24 hour care) and very painful. Laceration of the urethra would require urgent surgical repair and there is a high risk that the animal might develop urethral strictures (scarring and narrowing of the urine outflow passage) down the track. 

Excessive wound hemorrhage - excessive bleeding during or after surgery (rare).

It is very uncommon to have a pet bleed excessively from its incision site following a desexing surgery. They sometimes ooze a bit (an occasional drop here and there) a hour or so after surgery, but they do not normally pour blood.

Excessive bleeding may be a sign that the veterinarian has not performed the surgery properly (e.g. has lacerated the penis or a major blood vessel or not tied off the testicular stump properly), however, in these cases, the vet is usually aware of a mistake having been made at the time of surgery and will have taken steps to repair it prior to waking the dog up. More commonly, excessive bleeding from the surgical site is an indication that the pet has some kind of significant blood clotting disorder including: hemophilia, von Willebrand disease (vWD), rodent poison ingestion or a low platelet number problem (e.g. platelet deficiency, thrombocytopenia, ITP). 

If excessive wound bleeding is observed, the animal needs to go back to the vet or (if it is afterhours) to the nearest emergency center for treatment and work-up. This is particularly so if the animal looks at all pale or white in the gums (pale or white gum colour is often a sign of severe blood loss and shock setting in). Animals with severe bleeding may require a blood transfusion and supportive care (perhaps even an exploratory surgery to find a ruptured blood vessel) to save their lives. 

 Failure to ligate (tie off) testicular vessels adequately (uncommon).

This is the diagram picture presented earlier which shows the reproductive and vascular anatomy of the entire male dog. 


What you will notice is that the spermatic ducts (vas deferens) and blood vessels supplying each of the dog's testicles arises deep 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 dog's 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. 


It is important to understand this anatomy because it has a bearing on what can happen to the animal if the testicular vessels tear off or the vet accidentally fails to ligate the testicular blood vessels properly before cutting them (STEP 8 in section 4 of this page). If this occurs, the cut and bleeding ends of the testicular blood vessels will not remain under the skin and easily accessible. They will, instead, retract and spring back into the abdominal cavity and begin to hemorrhage out there, resulting in the animal developing a belly full of blood. The vet will need to cut quickly into the animal's abdominal cavity to find the bleeding vessel, tie it off and thus save the animal. If the vet fails to do this, the animal could die from excessive testicular artery hemorrhage and blood loss. Even if the vet does find the bleeder in time, animals with severe testicular artery bleeding may require a blood transfusion and further supportive care to save their lives. 

 Renal failure (uncommon in young, healthy animals).

Although anaesthetic drugs are much less cardiovascularly depressant (depressant on blood pressure) and rough on the kidneys and liver these days, there is still the possibility that an individual animal may develop acute renal failure immediately after or days after any anaesthetic procedure, even such a quick, routine procedure as neutering. 

Animals can develop renal failure because their blood pressure dropped below certain critical levels during anaesthesia (e.g. the animal received a drug that suppressed its cardiac contractility and heart-rate, resulting in reduced blood pressures). Kidneys require a certain pressure of blood to go through them in order for them to receive enough nutrients and oxygen to stay alive and functional (they are sensitive to low blood pressures and become damaged easily). Animals can also develop renal failure if they experienced a severe surgical complication that caused their blood pressures to fall critically during aneasthesia (e.g the animal experienced severe bleeding during the anaesthetic - see 6f-6g).

Kidneys require a minimum systolic blood pressure of 90mmHg and a mean arterial blood pressure over 60mmHg to survive. Blood pressures below these levels are very dangerous.

Animals may develop renal failure because they received an anaesthetic or pain-killer drug (or both) during the surgical procedure that had toxic side effects on the kidneys. For example, NSAIDs (non-steroidal anti-inflammatory drugs) used for pain relief act by inhibiting the formation of prostaglandin, a common chemical initiator of pain and inflammation (inhibiting prostaglandin is how these drugs reduce pain). Body prostaglandins, however, also have an additional role in protecting the kidneys from the damaging effects of low blood pressure (in times of low blood pressure the vessels leading into the kidneys release prostaglandins, which causes these vessels to dilate and the kidneys to, therefore, receive more blood and oxygen). NSAIDs inhibit the protective action of prostaglandin in the kidneys, resulting in a kidney that is more prone to becoming damaged if blood pressures fall (as they often do during surgery). 

Additionally, because the kidneys are designed to filter waste and toxins from the body, a lot of commonly-used anaesthetic and pain relief drugs require these organs in order to be cleared from the body. Kidneys, particularly kidneys already compromised by age, low surgical blood pressures or pre-existing disease, may not be able to tolerate these drugs moving through them and may, as a result, become injured and fail to function. 

Renal failure after surgery is more common when aged animals (>8 years) are operated on. These animals are more likely to already have some degree of renal compromise and the compounding effects of low blood pressures during anaesthesia as well as renal-toxic drugs (esp. non-steroidals), can be enough to push their kidneys over the edge. It is for this reason: to detect mild, sub-clinical renal disease that might be exacerbated by surgery, that most vets insist upon pre-anaesthetic blood panels being performed prior to performing surgery on older animals. 

Young animals, however, are not immune from suffering the effects of acute renal failure after surgery. Certain breeds: e.g. Staffordshire Bull terriers (Staffies), English Bull Terriers, Shar Peis, Beagles, Basenjis, Cairn Terriers, Tibetan Spaniels, Dobermanns, Elkhounds, Samoyeds and many others are prone to various congenital renal defects. Affected animals are more likely to already have some degree of renal compromise by the time of neutering and the compounding effects of low blood pressures during anaesthesia as well as renal toxic drugs (esp. non-steroidals), can be enough to push their kidneys over the edge, even though they are only young animals (and thus, presumably healthy). It is for this reason: to detect mild, sub-clinical, congenital renal disease that might be exacerbated by surgery, that many vets offer pre-anaesthetic blood panels prior to performing surgery on young animals. It is often a box that can be ticked on the anaesthetic permission form. 

Animals that develop acute renal failure after surgery will often become very sick over about 24-72 hours. They will drink excessively or not at all, they will go off their food, they will often vomit (the vomit may contain blood), they will become very depressed and listless to the point of being non-responsive, they will be dehydrated, they will stop urinating and they may start to pass black, tar-colored faeces or diarrhea. 

Animals presenting with these signs must see a vet. They will require aggressive and intensive (and expensive) therapies to save their lives. Many animals with severe, acute renal failure will not recover. 

The risk of post-operative renal failure can be reduced by letting the vet perform a pre-anaesthetic blood profile on your pet, young or old, prior to surgery. This way, early renal disease may be picked up. Vets can reduce the risks of pets developing renal failure by performing swift surgeries; monitoring blood pressures during surgery and by not giving the animal non-steroidal drugs prior to surgery, only afterwards as the pet is recovering. 

 Anaesthetic death (rare but does occur).

Very rarely, but often enough that most vets will have encountered a few during their careers, a young "healthy" animal booked in for a routine desexing procedure will inexplicably die. This is, needless to say, very distressing for the owner and for the veterinarian (having had one inexplicable death myself, I do vouch for this) and people will demand answers. The fact of the matter is that, while in some cases we can determine the cause of anaesthetic death (e.g. the animal bled to death because it had eaten rat poison and no-one knew about it; the animal developed an acute, fatal anaphylactic reaction to an anaesthetic drug; the animal was not monitored properly during or after anaesthesia and died; the animal vomited on recovery, inhaled its vomit and died and so on), in a good many more cases the reason for death can not be determined. The animal simply died and we have no idea why. We presume that these animals may have had a pre-existing disease; suffered a sudden, fatal heart arrhythmia (a heart problem never picked up before); suffered a "stroke" or thrown a blood clot into the lungs or heart, but we never actually find the cause of death. 
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