Risks & Common Complications KZN




Standing Castration

Intra-Articular Injections

Nerve Blocks

Intravenous Injections & Cather Placement

Intramuscular Injections


Nasogastric Intubation

Rectal Examination

Caslicks Operation

Wound Repair

Risks of General Anaesthesia

Complications of Surgery Under GA

Colic Surgery

Rig Surgery & Castration Under

General Anaesthesia


Riding on Our Premises


Inherent risks and complications associated with open castration can occur during, immediately following or days after the procedure and range from minor to life threatening. If any of these complications are noticed after discharge from the hospital contact your veterinarian immediately.

Haemorrhage: Can range from occasional blood drip (normally self-limiting) to severe bleeding from the testicular artery. Very rarely, after release of the emasculators, the spermatic cord may retract deep into the inguinal canal and the bleeding can occur directly into the abdomen. In this situation, haemorrhage may go unnoticed initially until signs of severe blood loss are presented (weakness, pale mucose membranes, etc). In severe cases, it may become necessary to induce general anaesthesia to find and tie-off the bleeding vessel.

Eventration:  Prolapse of abdominal contents (omentum and/or small intestine) through the scrotal incisions. This is a rare but often a fatal complication unless corrected immediately. Correction involves a general anaesthetic and replacement of the abdominal contents.

Swelling: Some degree of post operative swelling is normal. Mild swelling may cause discomfort and stiffness. Moderate swelling can indicate local infection, inadequate drainage or haematoma formation. Severe swelling may induce secondary problems such as phimosis, paraphimosis, wound infection and impaired urination. If the surgical incision(s) close prematurely it is often necessary to re-open the surgical site to allow drainage of accumulated fluid. This is done standing.

Infection: Can range from mild local infection around the scrotal incisions (with purulent wound discharge and sometimes increased rectal temperature) to regional cellulitis that occasionally can spread to the lower trunk and hind limbs. In severe cases, infection can reach the abdomen resulting in peritonitis and septicaemia. More delayed, persistent, chronic post-castration infections can occur in the form of protrusions of granulation tissue from the wound edges and scirrhous cord formation. These can be managed with a long course of antibiotic therapy and/or surgical excision of the infected tissue.

Hydrocele: Accumulation of fluid within the remnants of the vaginal tunic. Treatment

consists of surgical removal of the redundant vaginal tunic.

Tetanus: When adequate tetanus prophylaxis has not been undertaken. Please ensure that your horse’s vaccination status is updated. If your horse has not had a tetanus vaccine in the last six months please let us know so that we can provide a booster prior to gelding.

Iatrogenic trauma: Accidental trauma to the penis if sudden movement or kicking by the horse occurs. Sudden kicking is common, even when the horse is heavily sedated, and self-inflicted trauma can occur (for example fracture of the coffin bone if the horse kicks the wall).


Intra-articular injections are normally performed for the management of synovitis osteoarthritis and for routine lameness investigations. Complications of intra-articular injections can result in severe long-term consequences for joint function, even if such complications are treated successfully. After this procedure, please report any swellings, increased lameness or signs of discomfort immediately to your veterinary surgeon.

Infection.  Aseptic preparation is always performed before any intra-articular injection by scrubbing the area extensively with appropriate antiseptic solutions, without clipping the hair over the site. (The results of a recent study indicated no significant difference in the number of post-scrub bacterial colony forming units between clipped and unclipped skin over the coffin and the knee joints). Sterile latex gloves are always used. Despite all the precautions, there is always a risk of introducing infection at the time of injection that may result in septic arthritis. This is a serious complication and carries a guarded prognosis.

Post-injection flare. This is a rare complication and consists of acute inflammation of the lining of the joint (synovium) and occurs soon after injection of the joint with certain medications, combinations of solutions and/or local anaesthetics. This complication is due normally to the irritating nature of some of these drugs. Failure to provide prompt and adequate treatment may lead to septic arthritis.

Local swelling. A transient local swelling can occasionally occur at the site of injection which usually dissipates within 24-36 hours. They are normally caused by a small subcutaneous haematoma formation.

Laminitis. An association between intra-articular injection of corticosteroids and the development of laminitis, in otherwise apparently healthy horses, has been observed clinically. However, a cause and effect has yet to be proved.

Needle breakage.  If sudden movement of the horse occurs during injection.

Intra-Articular Corticosteroids - *NB: In line with recent scientific publications, we use small volumes of short acting corticosteroids intra-articularly. This method has been shown to have no deleterious effect on joints and is in fact chondroprotective (ie: at these levels it’s protecting the joint). Furthermore low dose short acting corticosteroids have been shown to cause no further deleterious effects even with osteochondral fragmentation in the joint (a chip fracture).


Local swelling. A transient local swelling can occasionally occur at the site of injection which usually dissipates within 24-36 hours. They are normally caused by a subcutaneous reaction to the local anaesthetic and/or haematoma formation.

Infection. Can range from mild skin infection to marked subcutaneous inflammation and cellulitis. In some severe cases, sloughing of the skin may occur. Some nerve blocks are performed in areas close to joints or other synovial structures like tendon sheaths or bursae. We prepare sites for nerve blocks using an aseptic technique, but there is still a small risk of synovial sepsis (see above) following a nerve block.

Needle Breakage. If sudden movement of the horse occurs during injection.

Temporary loss of limb function. Regional nerve block of the upper limb may result in loss of motor function and stumbling which is usually temporary.


The external jugular vein on either side of the neck is the most commonly used for medication delivery. The risk of complications increases with the frequency of injections. Please report any swellings at the site of injection to your veterinary surgeon

Thromboplephitis. Blood clot formation and inflammation of the vein wall at the site of injection with (septic) or without (non-septic) associated infection. Severe and/or chronic cases which do not respond to medical management may warrant surgical intervention. Bilateral jugular thrombophlebitis may result in oedema (swelling) of the head, which may cause dysphagia (difficulty to swallow) or dyspnoea (difficulty to breath). Inflammation in the area of the left or right jugular vein depending on which side the injection was given can in rare instances lead to pathology of the nerve supplying the larynx leading to paralysis of one side of the larynx (roaring).

Local cellulitis. Infection of the skin at the site of jugular injection.

Haematoma formation. Caused by leakage of blood from the injection site after removal of the needle (particularly if large-gauge needles/catheters are used).

Thromboembolism. This occurs when a blood clot formed at the site of injection, dislodges from the vein wall and flows freely until it becomes trapped in smaller blood vessels and capillaries. This situation may compromise the blood supply of the organ/organs that are “fed” by those vessels affected.

Catheter embolism. This occurs when a fragment of the catheter becomes free and is carried by the blood flow until it lodges in a smaller vessel, the heart or a pulmonary artery.

Drug Reactions: There is potential for adverse reaction to any medical product. The severity of an adverse reaction ranges from mild (for instance manifesting as urticaria or hives) to (more rarely) severe anaphylaxis that can result in death. It is possible that hypersensitivity can develop to a drug that has been given in the past.

Corticosteroids Clinical observations suggest that corticosteroids may induce laminitis in otherwise healthy horses.

Antibiotics. Alterations in the normal intestinal bacterial flora that may lead to diarrhoea and/or colic.

Phenylbutazone and other NSAID. They can cause ulceration of the stomach and kidney and liver disease.

Vitamins. Injection of some vitamins can lead to temporary hypotension that may cause the horse to stumble and fall.

Anaphylactic shock.  Unusual and exaggerated allergic reaction to certain substances. Occasionally these reactions may be fatal.

Sedatives. Occasional stumbling and/or collapse in certain horses particularly sensitive to sedatives


Please, report any swellings or abnormalities at the site of injection to your veterinary surgeon

Abscess formation: abscessation is an uncommon side effect of intramuscular injection that can be due to a primary adverse reaction to the product injected (see above), infection or a combination of the two. Typically these can be treated effectively but may result in some significant scarring.

Muscle soreness. It is fairly common, in particular neck soreness. It is related to volume administered, drug irritation and associated inflammation.

Adverse Drug Reactions: See above


Routinely performed for evaluation of the laryngeal function at rest and collection of tracheal samples in the unsedated horse.

Nasal haemorrhage. Caused by trauma with the end of the scope to the extremely vascular nasal, laryngeal and tracheal mucosa. It is normally consequence of sudden movement of the horse while performing the endoscopy. Usually almost all nosebleeds eventually stop even though their duration often seems prolonged.

Head trauma.  Self-inflicted trauma to the head in fractious horses.


Routinely performed for administration of oral medication, wormers, electrolytes, etc, and for diagnosis and treatment of colic.

Nasal haemorrhage and head trauma. See above (Endoscopy)

Aspiration of fluid into lungs: occasionally fluid can travel into the lungs, either due to movement of the horse or due to extreme reflux of gastric content. The consequences of aspiration are usually very severe, resulting in pneumonia and serious illness.


Any rectal examination carries an inherent risk, and even the most experienced of practitioners will at some point in their careers observe some of the following complications, following a rectal examination of a horse.

Rectal tears. Diagnosed when there is blood present in the glove after performing a rectal exam. They are graded from 1 (tear of the mucosa) to 4 (complete perforation of the rectum). Grades 3 and 4 are serious complications that will lead to peritonitis and death. They occur more commonly in colts and very excitable individuals, but they can also occur in quiet and sedated horses.

Rectal prolapse.  Protrusion of the rectum through the anus. There is usually a good response to management if only the rectal mucosa is involved. In severe cases where the rectal wall is involved, surgical treatment may be required.

After this procedure, please report any signs of straining, colic or abnormal discharge immediately to your veterinary surgeon.


Infection: Skin infection and wound breakdown.

Rectal prolapse: This is an extremely rare complication that may occur if discomfort in the operation site causes excessive straining.


Please refer to the sections pertaining to intravenous infection, sedation, adverse reactions, tetanus risk, intra-articular injection and nerve blocks.

Infection: Skin infection and wound breakdown which may be complicated by cellulitis, systemic illness (elevated rectal temperature).


There is an inherent risk to every general anaesthetic but on the whole, elective procedures in healthy patients carry a low risk. Surgery performed in emergency situations however are more risky, usually due to some degree of compromise to the horse prior to anaesthesia.

Risks involved in general anaesthesia include but are not restricted to:

•   Trauma to the upper respiratory tract during placement of an endotracheal tube.

•   Death due to the effect of the inhaled anaesthetic agents, which can in rare cases cause severe respiratory depression and cardiac collapse.

•   Adverse (anaphylactic)  reaction to any of the drugs used as part of the anaesthetic protocol (including procaine penicillin G)

•   Damage to muscles and/or nerves of the muscles, particularly the hind quarters. This is a bigger problem in heavier horses and those under general anaesthesia for prolonged periods, typically over two hours. The severity of this complication ranges from being mild (similar to ‘tying-up’) to severe, which can prevent the horse from standing and also predispose to injury such as fracture during recovery.

•   Prolonged recumbency results in compression of the lungs, both from the weight of the horse and also the abdominal contents pressing on the diaphragm. This combined with the occasional need for ventilation under general anaesthesia can predispose to lung problems such as pulmonary oedema, a reduced lung capacity in recovery and also infection (pneumonia).

•   Most complications occur in recovery. This is due to the ‘hangover’ effects of the anaesthetic agents combined with the natural flight response of the horse to perceived dangerous situations. This can result in the horse trying to rise before it has complete command of its balance and limbs. This means that occasionally a horse can be at risk of the following:

- Fracture and/or soft tissue trauma

- Head trauma

- Asphyxiation or reduced oxygen intake

In addition to the risks of the anaesthetic drugs there are also risks from procedures relating to performing the anaesthetic, refer to other sections of this guide pertaining to

- Intravenous injection

- Intravenous catheter placement

- Intra-articular injection

- Nerve blocks


There are specific risks posed by each surgical procedure in addition to the risks of the general anaesthetic. These risks vary according to the surgery being performed and are outlined but not limited by those below:

Arthroscopic Surgery:

This involves placement of a camera and instrumentation into a joint or tendon sheath for the performance of ‘keyhole’ surgery. Specific risks for these types of procedure are outlined below, and you may also refer to the intra-articular injection section of this guide.

•   Infection of a joint or tendon sheath is potentially life threatening and is a potential risk following any procedure where a synovial structure is entered.

- infection

- swelling

- lameness

•   If an orthopaedic implant is used, such as a screw or plate, there is a small risk that the horse will suffer from pain associated with the implant that may require its removal. Similarly infection associated with an implant may also require implant removal. Positioning of the implant is of great importance and it is for this reason and to monitor for the complications outlined above that we frequently need to take x-rays after surgery is finished, often up to months post operatively.

•   Post  operative  pain  is  often  a  problem  following  orthopaedic  surgery,  requiring management with drugs like phenylbutazone. As well as the side effects of prolonged usage of these drugs, pain is also a factor contributing to post operative complications such as colic and laminitis in the other limbs.

Post-operative complications

•   colic- eg impaction secondary to discomfort following surgery or colitis associated with antibiotic or non-steroidal usage used for pain management.

•   Laminitis can become a problem particularly if the horse is experiencing significant pain in one limb. This can cause the horse to bear weight unevenly which predisposes to laminitis in the ‘good’ leg.

•   Most orthopaedic procedures require extensive bandaging post operatively. This provides support to the limb, helps the horse to use the affected limb safely, reduces the chance of post operative infection, and also helps to minimize swelling. However there are complications associated with bandaging, particularly hard casts and large bandages that must be left in place for a number of days. Typically complications include sores over pressure points and occasionally damage to soft tissues such as tendons.


The anaesthetic risk is increased for colic patients due to the frequent compromise to the cardiovascular system and increased incidence of endotoxaemia, sepsis or shock. These may result in death of the patient in induction of anaesthesia, during surgery or recovery from anaesthesia despite every effort to stabilize the patient.

Furthermore there are other risks specifically related to colic surgery. These are outlined but are

not limited to those below:

•   It may not be possible to successfully correct the problem which may result in perioperative fatality. This may be due to any number of factors such as

- devitalisation of such a large percentage of gastrointestinal tract that recovery is extremely unlikely

- failure of other body systems secondary to the colic such as fatal cardiovascular collapse

- findings on opening the abdomen that preclude successful recovery such as

rupture of the - gastrointestinal tract

•   Following successful recovery, additional risks to colic surgical patients include

- Recurrence of colic, either immediately after surgery or at some stage in the future. There is a higher risk of colic occurring again in any horse that has undergone colic surgery in the past.

- Peritonitis (infection of the abdominal cavity) which can be life threatening

- Eventration (gastrointestinal tract escaping from the surgical site, which unless replaced immediately is frequently fatal).

Infection of the abdominal incision, which in turn predisposes to peritonitis and eventration

Sepsis (systemic infection) due to compromise of the gut-body barrier, causing shock. This is also something that can occur pre-operatively and is also a potential fatal sequelae of colic.

RISKS RELATING TO RIG SURGERY (removal of undescended or partially descended  testes) AND GELDING UNDER GENERAL ANAESTHESIA. (for routine standing geldings  see previous section ‘castration’):

Rig surgery is performed utilizing different methods according to the location of the testicle.

•   A ‘high flanker’ testicle is descended but not accessible when the horse is standing. Once

the horse is recumbent the testicle is removed routinely

•   A testicle that lies in the inguinal canal (partly held in the channel from the abdomen to the scrotum) requires a more invasive surgical approach to exernalise the testicle. Therefore there is a higher risk of complication such as haemorrhage and herniation of gastrointestinal tract through the inguinal ring.

•   It is occasionally necessary to make an incision into the abdomen to facilitate exteriorization of the inguinal testicle, and entrance into the abdomen carries a higher risk

•   If the undescended testicle is not palpable in or near the inguinal ring using the techniques outlined above, it becomes necessary to open the abdomen in a manner similar to that used for a colic operation. This therefore carries similar risks to colic surgery in terms of recovery (see previous sections pertaining to eventration, peritonitis, abdominal incision infection).

•   Warm bloods carry a higher risk of eventration following routine gelding, and so we recommend that all warm blood geldings are performed under general anaesthesia to facilitate tying-off of major vessels and also closure of the sac that contained the testicles.

•   Older stallions with well developed testes are also more prone to post operative haemorrhage due to the larger size of the blood vessels supplying the testes. We therefore also recommend that these horses are gelded under general anaesthesia to facilitate tying-off of the vessels. This risk is also increased in donkeys and miniature ponies, and so we recommend gelding under general anaesthesia in these cases also.


A “tieback” surgery is the preferred treatment for racehorses with laryngeal hemiplegia/paresis (also known as roaring/whistling/gone in the wind). A “hobday” surgery (ventriculectomy) is normally performed at the same time. A presumptive diagnosis of laryngeal hemiplegia can often be made from a clinical examination and a resting endoscopic examination, however a dynamic upper respiratory examination is the preferred diagnostic modality.

•   A “tieback” surgery in a racehorse should be considered a salvage procedure and there is no guarantee of a return to previous levels of performance.

•   Success rates of between 60-70% are considered normal worldwide for this surgery.

•   The best results tend to be in proven athletes racing over short to middle distances.

•   A reduction in abnormal respiratory noise at work is desirable post operation however some horses who make no respiratory noise fail to return to previous levels of performance and vice versa some who do have a residual abnormal respiratory are able to perform satisfactorily.

•   Post operative complications for “tieback” surgeries are not uncommon. eg. wound breakdown/infection, chronic coughing, difficulty swallowing, food aspiration, persistent respiratory noise.   Most complications are generally manageable   however this may require additional veterinary intervention.

•   In cases with persistent respiratory noise a dynamic upper respiratory examination at exercise should be performed.

•   On rare occasions post operative complications carry a poor prognosis for return to racing and may even be life threatening eg. infection and inflammation of the laryngeal cartilages, aspiration pneumonia

•   Due to the occasional serious complications associated  with tieback surgery, a hobday surgery (ventriculectomy) on its own should be considered as the first line of treatment to eliminate the respiratory noise in horses performing at submaximal exercise intensities.

•   Horses who have had a tieback surgery have an increased risk of developing travel sickness when being traveled over long distances.



We remind you that there are inherent risks to riding horses at any time, but to be aware that in the unfamiliar setting of the veterinary hospital your horse may be more prone to spook and behave in an unusual manner. We therefore ask that you take every precaution for your own and your horses safety and wear a hard hat conforming to current safety standards and a back protector if you are able. In this vein we cannot accept liability for any injury sustained by you or your horse whilst exercising on the premises.