All surgical procedures have the following potential complications: haemorrhage, infection, pain, neurological problems and iatrogenic or inadvertent injury.
The consequences of a horse suffering one or more of these conditions can range from minor to fatal, depending on the degree to which the horse is affected and the organ system involved. SEH Veterinarians are aware of the risks and potential consequences of surgery and act to manage these risks as far as is practically possible.
Occasionally and in spite of all precautions, horses suffer one or more of these general complications when they undergo surgery. This most commonly occurs when the horse is already suffering from disease or injury, is very young or is an older animal; however it can also happen to horses which appear fit and healthy and show no signs of compromise prior to surgery.
General surgical risks include:
Haemorrhage
Surgical procedures can result in bleeding or haemorrhage from the surgical site. This can range from minor bleeding of little consequence to severe haemorrhage that could potentially be life threatening. Circulatory blood volume is maintained during anaesthesia using intravenous fluid therapy and in some surgical cases where increased blood loss may be anticipated, blood transfusion may be peformed during surgery. However, in an emergency situation donor blood is usually not available in horses and severe haemorrhage can be fatal.
Infection
Bacterial tissue infection can occur following surgical procedures. Risk of infection is significantly increased with tissue trauma, compromised patients, prolonged surgery times, and surgical implants such as orthopaedic plates and screws. Antibiotics are commonly administered prior to and after a surgical procedure to reduce the risk of bacterial infection. Occasionally, and in-spite of all precautions infection can occur that can range from minor wound infection to systemic infection that could lead to other complications eg septic shock, endocarditis, that may require intensive treatment and could potentially be fatal.
Pain
All surgical procedures are invasive and will stimulate a pain response in the patient. In order to safely perform surgical procedures on horses a combination of sedation and local anaesthesia or general anaesthesia is necessary. Sedative and anaesthetic drugs provide an analgesic or “painkilling” effect which varies depending on the drugs used.
Non steroidal anti-inflammatory drugs (NSAIDs) such as phenylbutazone are also routinely administered prior to surgery to help reduce any pain response. Controlling pain is very important and significantly reduces the risk of complications during and in recovery from anaesthesia as well as minimizing stress for our equine patients and providing for their welfare.
Neurological Problems
Damage to nervous system is a rare complication associated with surgery. Very rarely damage to the brain or spinal cord (central nervous system CNS) may occur associated with spread of blood clots from a surgical site. Damage to the CNS may also occur if there is decreased blood supply ie severe haemorrhage or decreased oxygenation of the blood. Acute blood loss can occasionally cause blindness that may be permanent and irreversible. Additionally, myopathy or neuropathy may occur occasionally as a complication of general anaesthesia. This can rarely result in a horse that is unable to stand in recovery and may lead to death.
Iatrogenic / inadvertent Injury
Accidental injury may occur in any procedure and accidental tissue damage may occur during any surgical procedure. The consequences of this injury will depend on the tissue involved.