Anaesthesia

If your pet is undergoing diagnostic procedures or surgery at UCD Veterinary Hospital, then analgesia, sedation or general anaesthesia may be required.

A dedicated team of anaesthetists at UCD Veterinary Hospital provide anaesthesia for over 2,000 dogs, cats, horses, cattle, sheep, goats, pigs and exotics pets each year. Our team includes three European specialists in veterinary anaesthesia, one anaesthesia registrar, two anaesthesia residents, one anaesthesia intern and three small animal anaesthesia nurses.

Anaesthesia, like any medical procedure, carries inherent risks including, but not limited to, low blood pressure, respiratory depression, adverse reaction to anaesthetic drugs and allergic reactions. For this reason, each patient has an anaesthetist dedicated to their case, with supervision provided by a European specialist in veterinary anaesthesia. When anaesthetic cases are particularly complex there will be two anaesthetists assigned to a case, again with support provided by a European specialist in veterinary anaesthesia. 

• European Specialist in Veterinary Anaesthesia
  • A qualified veterinarian, who after graduation has completed at least a one-year veterinary internship (junior veterinary training programme) and a three-year anaesthesia residency (advanced postgraduate anaesthesia training programme) and has passed their anaesthesia specialist qualifying examinations. In many instances, anaesthesia specialists go on to obtain further qualifications in teaching and research.
• Anaesthesia Registrar
  • A qualified veterinarian, who has completed at least a one-year rotating internship and a  three-year anaesthesia residency and is now preparing to sit anaesthesia specialist qualifying exams.
• Anaesthesia Resident
  • A qualified veterinarian, who has completed at least a one-year rotating veterinary internship and is now enrolled in a three-year anaesthesia residency.
• Anaesthesia Intern
  • A qualified veterinarian, who is enrolled in a one-year anaesthesia training programme.
• Veterinary Nurse in Anaesthesia
  • A qualified and registered veterinary nurse, who after graduation has gained additional specialised training, skills and knowledge in veterinary anaesthesia. 

• Sedation
  • A mental calming effect, characterised by sleepiness and disinterest in their environment, produced by the administration of certain anaesthetic drug(s).

• Analgesia
  • A loss/lack of pain perception

• General anaesthesia
  • A state of unconsciousness produced by the administration of anaesthetic drug(s).

There are several specialised procedures which are routinely performed at the UCDVH. Many of these procedures require specialised training and equipment. Below are some examples of specialised procedures performed at the UCDVH, however this list is not exhaustive.

• Regional anaesthesia
  • Regional anaesthesia is a type of pain management that numbs the part of the body that has been treated. It is the most effective way of providing intraoperative analgesia and will be performed in most surgical patients if feasible. An example of regional anaesthesia which most people have experienced is the injection of local anaesthetic for tooth extraction while at the dentist. Regional anaesthesia for tooth extraction is commonly performed for dental procedures also in anaesthetised veterinary patients. Another form of regional anaesthesia is epidural anaesthesia (the deposition of local anaesthetic around the spinal cord), which causes loss of pain sensation in the hindquarters, providing excellent analgesia for painful hindlimb surgery. 
  • There are many other forms of regional anaesthesia, which can be performed to optimise pain relief in our surgical veterinary patients. These include nerve blocks that can be performed with the aid of ultrasound, such as forelimb (RUMM), abdominal (TAP), spinal (ESP) and hind limb (femoral and sciatic) nerve blocks.The use of ultrasound for precise needle placement and local anaesthetic administration is a specialised technique known to significantly enhance the safety and success of these blocks. This technique, routinely practiced in our anaesthesia department with a dedicated ultrasound machine, enables the anaesthetist to track the needle's path as it moves through tissues towards the targeted nerve.

• Invasive blood pressure
  • Invasive blood pressure is measured by placing a catheter in a distal artery and measuring the pressure within the artery using a pressure transducer. Invasive blood pressure is the gold standard technique for blood pressure measurement allowing continuous blood pressure assessment. High-risk patients undergoing general anaesthesia at UCDVH will have their blood pressure measured directly, using this invasive technique.
• Central venous catheter placement
  • A central venous catheter is a catheter placed into a large central vein in the body, most commonly the jugular vein with the tip of the catheter lying close to the heart.  Central venous catheters are placed under sterile conditions and can stay in place for a number of weeks, longer than that of ordinary intravenous catheters. Central venous catheters allow rapid fluid and drug administration and painless blood sample collection. 
• Blood product administration (blood, plasma, albumin)
  • The administration of blood products to veterinary patients in need of them can be lifesaving, for example, in cases of severe blood loss during surgery. A huge thanks must go to all the dogs, cats, horses and farm animals who have donated blood to our patients, and to their owners, who have given their time to our Veterinary Blood Donor Programme. 
  • The administration of donor blood is not without risk. Recipients of blood products in some cases will mount an immune response to the foreign blood. Patients receiving blood products are monitored closely for evidence of this immune response and blood product administration is stopped if such a reaction becomes evident; in some instances it is possible to restart the administration of donor blood at a slower administration rate.    
• Mechanical ventilation
  • Many of the drugs given during anaesthesia can have a negative impact on the patient's ability to breath. In some instances during anaesthesia the patient will require assistance to breathe. This breathing assistance is normally provided in the form of mechanical ventilation, in that a machine will breathe for the patient.      
• Total intravenous anaesthesia
  • General anaesthesia is normally maintained by the breathing in of anaesthetic gases (inhalational anaesthesia). However, these gases can have a dose-dependent negative impact on the cardiovascular system. Therefore, in some patients it is safer to maintain anaesthesia with the total intravenous method.
  • During total intravenous anaesthesia, general anaesthesia is maintained by the administration of anaesthetic drugs injected directly into the vascular system. Total intravenous anaesthesia is associated with better maintenance of cardiovascular function, meaning that the patient is less likely to develop low blood pressure during anaesthetic maintenance. However, total intravenous anaesthesia is considerably more expensive than inhalational anaesthesia; in addition, the recovery from intravenous anaesthesia is less smooth than the recovery from inhalational anaesthesia.
• Neuromuscular blockade
  • Neuromuscular blocking agents stop the transmission of impulses along the nerves of muscles, leading to muscle relaxation. The muscle relaxation caused can improve surgical access and make it easier to realign fractured bone fragments. When neuromuscular blocking agents take effect, the patient will lose the ability to breathe, and assisted breathing must be provided by the anaesthetist through the use of mechanical ventilation (assisted ventilation). As the drug wears off, muscle function will gradually return and the patient will regain the ability to breathe spontaneously. Return of muscle function is monitored closely during anaesthesia and assisted breathing is only removed when the anaesthetist is sure that there is a full return of breathing function.

After admission the specialist team will provide an internal referral request to our anaesthesia department requesting service for the required surgery or procedure. A member of our team will then perform, plan and deliver the most appropriate analgesia, sedation and anaesthesia plan as listed below for the patient.

• History and clinical exam
  • The patient’s history and test results will be reviewed, and a full clinical examination will be performed by the anaesthetist in charge of the case.
• Anaesthetic plan
  • The anaesthetist will then generate an anaesthetic plan tailored to the patient’s individual needs, taking into account any underlying diseases (e.g. cardiovascular or respiratory-related problems) and the procedure/surgery to be performed. The anaesthetic plan is then discussed with a European specialist in veterinary anaesthesia.
• Pre-medication
  • Drugs are administered either intravenously or intramuscularly, which will provide both sedation and analgesia, prior to induction of anaesthesia. Patients are then placed in one of our anaesthesia kennels and observed continually, while these drugs take effect.  When the patient is calm and relaxed, an intravenous catheter is placed to allow safe delivery of intravenous drugs and fluids during the anaesthetic. In general, a small patch of hair will be clipped on the distal fore or hind limb to allow catheter placement.
• Anaesthesia
  • The patient is then positioned on an anaesthesia induction table and oxygen is provided via facemask for 3 – 5 minutes prior to induction of anaesthesia. Anaesthesia is normally induced with intravenous administration of drugs. The selection of drugs used to induce anaesthesia is specifically tailored to each patient. Upon drug administration, patients quickly become unconscious. An endotracheal tube is then placed in the airway, providing both protection for the airway and a route for delivery of oxygen and anaesthetic gases. Anaesthesia is generally maintained with inhaled anaesthetic gases. In high-risk anaesthesia cases, anaesthesia may be maintained with intravenously administered drugs.
• Monitoring
  • During anaesthesia, patient parameters are monitored continually and recorded every 5 minutes. Parameters monitored include:

1. Heart rate

2. Respiratory rate

3. Temperature

4. Inhaled and exhaled carbon dioxide concentration

   • Carbon dioxide is the waste gas produced by the tissues of the body.

5. Inhaled and exhaled oxygen concentration

6. Inhaled and exhaled anaesthetic gas concentration

   • Electrical activity of the heart

7. Electro-cardiography (ECG)

8. Oxygen percentage of the blood (pulse oximetry)

9. Blood pressure

   • Routine anaesthesia cases will have blood pressure measured non-invasively using a blood pressure cuff.

   • High-risk anaesthesia cases will have their blood pressure measured directly, by placing a catheter in a distal artery and measuring blood pressure directly using a pressure transducer. This is the gold-standard technique for blood pressure measurement.

Below is an image of one of our patient monitors, showing all monitored parameters.

• Support during anaesthesia
  • Support is provided in several different ways during anaesthesia, including:

1. Fluids are administered intravenously, to maintain the patient’s blood circulation and to replace any fluid losses during the procedure/surgery.

2. Active warming is provided with the use of heat mats, forced air warmers, bubble wrap and blankets.

3. Ventilatory support is provided if the patient is not breathing adequately. In such cases ventilators will take over the role of breathing for the patient.

4. Blood pressure support is provided if the patient’s blood pressure decreases during the anaesthetic.

5. Analgesia (pain relief) provision during the procedure/surgery and throughout the recovery period is tailored to the patient’s individual needs.

• Recovery
  • When the procedure/surgery is complete, the delivery of anaesthetic gas will be stopped and the patient will be allowed to recover. Once sufficiently awake, the tube delivering oxygen and protecting the airway will be removed. Supplemental oxygen and active warming will continue to be provided until the patient is completely recovered from anaesthesia. During the recovery period the patient will be monitored continually. When continuous monitoring is no longer deemed necessary, the patient will be moved to hospital wards for close observation.