Anesthesia is a drug-induced loss of sensation with or without loss of consciousness.
In veterinary medicine, anesthesia facilitates painful or lengthy procedures such as surgery. Non-surgical procedures that might require anesthesia include:
- diagnostic imaging (x-rays, CT scans, MRI)
- endoscopy
- radiation treatments
Further information: A Primer on Anesthesia in Dogs
We decided on general anesthesia for Cookie’s follow-up PRP treatment because of the reaction she had to the deep sedation .
Sedation versus anesthesia
The choice between heavy sedation or general anesthesia depends on the procedure and individual considerations.
Anesthesia
Local anesthesia is the loss of sensation and pain in a particular part of the body while the dog remains conscious.
General anesthesia involves both loss of sensation and awareness of pain as well as a loss of consciousness.
A veterinarian will use general anesthesia for long, painful, or invasive procedures such as:
- surgery
- dental work
- endoscopy
- radiation treatments
Before anesthesia is administered, a dog is usually premedicated with a sedative. That helps to reduce stress and facilitates a lower level of anesthesia drugs, which helps faster and smoother recovery. General anesthesia usually involves the administration of gases, but can be done with injectable agents (such as propofol or alfaxalone) only.
Depending on the procedure, the veterinarian might add pain medications as well.
Anesthesia protocols have improved in terms of safety, monitoring, and precautions. The advantage of anesthesia over sedation is that it can be adjusted on the fly. As well as a dog under general anesthesia already has a breathing tube and IV lines to quickly intervene when needed. Another advantage is that the patient stays still, which is not guaranteed with sedation alone and can be very important.
Careful monitoring during anesthesia is vital.
Further information: 2020 AAHA Anesthesia and Monitoring Guidelines for Dogs and Cats
[Heavy] sedation
A veterinarian might use sedation for shorter and minimally-invasive procedures such as:
- diagnostic imaging
- joint injections
- suture removal
- wound management
Heavy sedation is induced by an injection. Depending on the protocol, a sedated dog can be brought back to an alert state with reversal agents—domitor/dexmedetomidine is reversible. Opiods can be reversed but it’s not done except in case of an overdose or adverse reaction.
A sedation protocol may include:
- tranquilizer (e.g. acepromazine)
- sedative (e.g. dexmedetomidine)
- opioid
Once the procedure is complete, the veterinarian wakes the dog up with a reversal injection. But it is only the sedative drug that can be reversed.
Typically, a sedation protocol contains a sedative and a tranquilizer. The tranquilizer facilitates a lower dose of sedative which can lower the dog’s heart rate. That is, however, the drug that caused Cookie’s adverse effects.
Pre-anesthetic blood work
Never skimp on pre-anesthetic blood work. It ensures that your dog’s liver and kidneys will be able to clear the drugs out of the system. Any existing health issue impacts what protocol and precautions the veterinarian needs to employ. And, in some cases, you might need to forego the procedure.
Breed-Specific anesthesia considerations
Many considerations go into a safe anesthesia protocol. The important factors are not only age and general health but also the breed of the dog. You might expect that in brachycephalic breeds, but did you know that other breeds have different needs too? Breed-specific considerations apply to:
- brachycephalic breeds
- toy breeds
- herding breeds
- Sighthounds
- Doberman Pinschers
- Boxers of UK lineage
- giant breeds
Further information: Canine Anesthesia: Special Considerations Based on Breed, Size, and Conformation
Breed-Specific anesthesia: Giant Breeds
Normally, drug dosages calculations are based on body weight. That, however, doesn’t work for large dogs. Dosage based on body weight is typically too much.
The reason behind higher drug sensitivity in giant breed dogs is their metabolic rate. Metabolic rate correlates to body surface rather than body weight. That means that it is harder for a large dog to clear the drugs out of their system. The ratio of body surface to body weight results in the need to calculate drug dosages differently.
Giant breeds often respond profoundly to normal therapeutic doses of sedatives, such as acepromazine … It is essential to lower the dose or calculate it based on lean body mass or surface area rather than body weight.
Clinician Brief
Further, giant breeds age faster, and senior dogs are at greater risk with general anesthesia. As well as just handling an unconscious large dog requires careful considerations.
Further information: Breed-Specific Anesthesia
Related articles:
A Primer on Anesthesia in Dogs: What Do You Need To Know About Anesthesia?
Further reading:
Anesthesia for Dogs
Canine Anesthesia: Special Considerations Based on Breed, Size, and Conformation
Some Breeds Handle Anesthesia Better than Others
Breed-Specific Anesthesia