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Anesthesia in dogs

Author: Rémi

What is anesthesia in dogs?

Anesthesia for dogs is the voluntarily reversible suppression of sensitivity caused by the administration of anesthetic products in the canine organism. The most frequently used and best known forms are local and general anesthesia.

Local anesthesia

The reversible loss of sensation is deliberately induced but targeted to a specific part of the body.

General anesthesia

The reversible loss of sensation is deliberately induced by the administration of drugs which then cause the reduction or total suppression of reflexes, thus providing the animal with insensitivity to pain and total immobility.

Whether local or general, anesthesia is usually used for therapeutic purposes to perform some surgeries or treatments while preventing the dog from suffering.

The process of anesthesia

Before anesthetizing a dog, some steps are necessary to ensure that the entire operation runs smoothly and that the animal is protected at all times.

Weighing

Weight determines the amount of anesthetic medication required for the dog.

Steps:

  • Weighing the dog
  • Determining the necessary dose of medication
  • Anesthesia based on a protocol adapted to the risk factors related to the weight of the dog

General examination and assessment of overall health status

  • Discussion with the owner about the dog’s medical history
  • General examination by the veterinarian
  • Additional examination if necessary

Heart auscultation

  • Detects a murmur in the heart
  • In the event of a heart murmur, investigate to determine the source
  • Assessing the severity of the heart murmur
  • Anesthesia based on a protocol adapted to the risk factors if necessary

Positioning of an intravenous catheter

  • Allows you to inject a sedative directly at any time if the need arises during the therapeutic procedure
  • Allows the injection of certain medications in emergency situations
  • Allows the injection of physiological saline to ensure the dog’s hydration throughout the procedure

Tranquilizing

  • Injection of an intravenous tranquilizer to quickly calm the dog, making it more comfortable for the animal
  • Tranquilizing the dog allows the veterinarian to carry out complementary care or examinations to the treatment
  • Allows for the optimization of the action of the anesthesia while reducing the necessary doses, thus greatly reducing the side effects for the animal

Induction

  • This is the moment when the dog is completely asleep
  • Injection of a short-acting anesthetic into the catheter or through the mask, releasing a mixture of gas and volatile anesthetic oxygen
  • Once induction is confirmed, a catheter is placed in the dog’s trachea to monitor all exhaled or inhaled gases throughout the anesthesia

Maintenance

  • This is the anesthesia phase where the surgical treatment is implemented
  • Injection of a long-lasting anesthetic or by breathing anesthetic gas
  • During this phase, all parameters are constantly monitored

Pain management

  • The veterinarian takes special care to control the dog’s pain
  • Morphine derivatives and NSAIDs (non-steroidal pain killers) are generally used
  • In order to allow the dog a comfortable post-operative recovery, the veterinarian generally uses epidural analgesia as soon as osteoarticular surgery involves the hind limbs

Monitoring

  • The devices used to control and monitor the dog’s vital signs at all times during anesthesia are called monitoring. Veterinarians generally use state-of-the-art monitoring technology that is often similar to that used in human medicine.

Surveillance

  • Heart
    • Permanent electrocardiogram possible with the use of electrodes
    • Monitoring the physical activity of the heart
    • Beat frequency monitoring
    • Indication of the percentage of oxygen saturation in the blood by a clamp on the tongue
  • Breathing
    • Analysis of exhaled and inhaled gases by the dog using a capnograph
    • The capnograph can also measure the amount of anesthetic gas exhaled and inhaled
    • It makes it possible to control accurately the intensity of the anesthesia
    • Artificial respiration is also possible when the necessary equipment is available
  • Control of reflexes & examination
    • Monitoring of physical features to properly assess the intensity of the anesthesia

Waking up

  • Temperature

Hypothermia is one of the side effects of general anesthesia. Usually, heat lamps or hot water bottles are used, as appropriate, to warm up the dog.

  • Breathing

An oxygen tank is usually available in case the dog suffers from respiratory failure.

  • Hydration

The intravenous infusion is maintained in the dog for as long as necessary.

  • Comfort

Most of the time, veterinarians have large cages allowing individual comfort for the dog in order to ensure a good post-operative recovery of the animal.

As with anesthesia in humans, general anesthesia in dogs carries risks. As in humans, the risk of death in dogs is also possible. According to some studies, the risk of death in dogs is about 0.18%, or 1.8 chances in 1000.

The causes of death during an anesthesia are various. In about 30% of the cases, the causes are completely unknown. For others, there are various factors that can increase the risk for the dog.

The risks of anesthesia in dogs

What are the risks of anesthesia in dogs? Several factors must be taken into account:

Initial state of health

Depending on the dog’s state of health before the procedure and anesthesia, the risks may increase. For example, a dog suffering from kidney failure is at higher risk of experiencing certain complications, sometimes even death.

Degree of urgency of surgical procedure

A surgical procedure that is planned and scheduled in advance is generally less risky than a procedure that must be performed urgently. For example, spaying or neutering a female will rarely lead to complications compared to an emergency cesarean section, where the risks are very high.

Severity of surgery

Major surgery is much more risky than minor surgery. For example, extracting a tooth is far less risky than open-heart surgery.

Patient weight – Too small

Very small dogs, those under 5kg (1lbs), are more at risk than large or very large dogs.

Patient weight – Obesity

The presence of abdominal fat in dogs produces the same phenomena as in humans and increases the risk of anesthetic complications in addition to lengthening the procedure.

Age of the dog to be anesthetized

The older the dog, the greater the risks associated with anesthesia.

Type of anesthesia

As there are several ways to proceed with anesthesia, depending on the type used by the veterinarian, the risks may vary.

Unlike humans, local anesthesia is rather rare in dogs. When a dog requires anesthesia, most of the time, it is a general anesthesia aiming to ensuring the immobility of the animal and at the same time, eliminating any form of pain.

As in humans, the risk of anesthesia is never nil in dogs either. This is why it is essential for the veterinarian to be familiar with all aspects of the dog and his health in general.

All relevant information should be given to the physician before anesthesia is administered to the dog to ensure that the risk of complications is minimized.

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