Anesthesia Guidelines: Dogs

Find guidelines for canine anesthesia, including recommended anesthetic drugs and procedures.

Research Animal Resources (RAR) veterinary staff designed these guidelines to be general recommendations, not an inclusive list of all possible drug combinations that can be used in canines. 

Consequently, they do not include reference to specific research-associated concerns. If you have questions about using anesthetics for your particular situation, please work with your area veterinarian to develop the most effective anesthetic plan.


General considerations

Acclimation

Do not use newly arrived animals for experimental procedures until 72 hours after entry into the facility. A one-week acclimation period is recommended. This stabilization period is not required for animals used acutely (anesthetized and euthanized at the end of the procedure), although it is recommended. This provision allows animals to acclimate to the facility and reduces the chance of stress-induced disease, including anesthetic death.

Fasting

Fast animals overnight prior to an anesthetic event. Never restrict water.

Heat

Because most anesthetic drugs cause hypotension and hyperthermia, provide supplemental heat to animals under anesthesia. Regardless of heat source, never place animals directly on the heat.

Catheterization

Place indwelling catheters for administration of anesthetic drugs, emergency drugs, and intravenous fluid support. The most common sites for catheter placement are the cephalic and lateral saphenous veins.

Fluid support

Provide supplemental fluid support in animals that will be under anesthesia for longer than 30 minutes. Appropriate fluid rates range from 5-10 mls/kg/hour, and may vary based on the anesthetic combination.  

Monitoring

Standard mammalian monitoring techniques apply to dogs. The goal of monitoring is to maintain cardiovascular homeostasis and core body temperature. 

Understanding the basic physiologic effects of the anesthetics used is paramount to correctly interpreting monitoring parameters. View descriptions of anesthetic agents

Parameters to monitor in anesthetized dogs include anesthetic depth, heart rate, respiratory rate, oxygen saturation, expired CO2 (EtCO2), temperature, blood pressure, and mucous membrane color.

Normal ranges (without anesthesia)

  • Temperature = 100-102.5°F
  • Heart rate (beats/minute) = 70-180
  • Respiratory rate (breaths/minute) = 20-40 resting
  • Blood pressure = >60 mm Hg (mean) and >90 mm Hg (systolic)
  • Oxygen saturation = >95%
  • EtCO2 = 35-45
  • Mucous membranes = pink, not pale, white, gray, or blue

Normal ranges (with anesthesia)

  • Temperature = >98°F
  • Heart rate (beats/minute) = 60-140
  • Respiratory rate (breaths/minute) = 6-20
  • Blood pressure = >60 mm Hg (mean) and >90 mm Hg (systolic)
  • Oxygen saturation = >95%
  • EtCO2 = 35-55 
  • Mucous membranes = pink, not pale, white, gray, or blue

For more involved procedures, EKG, invasive pressure monitoring, and blood gas analysis may be indicated.  


Anesthetic drugs and procedures

Canine anesthesia is generally broken into premedication (sedation), anesthetic induction, and anesthetic maintenance.  

As with other species, anesthesia (maintenance) can be accomplished via inhalation or parenteral methods.  

Sedation

Sedation

Administering sedative drugs decreases excitement and causes relaxation to allow for the placement of indwelling catheters (for IV drug and fluid administration) or allow for intubation (for inhalation anesthesia). 

Induction (see below) is required in addition to sedation to provide a sufficient level of sedation/anesthesia for intubation. 

The anticholinergic glycopyrrolate (0.004-0.01 mg/kg IM) may be used as a premedication to dry oral and respiratory secretions and for its vagolytic effects (i.e., ability to block vagal nerve stimulation and consequent bradycardia) during endotracheal intubation.

For sedation, the intramuscular (IM) route is most common.


Acepromazine

Dose: 0.025-0.2 mg/kg – IV
Dose: 0.1-0.25 mg/kg – IM/SQ
Comments: Moderate sedation, no analgesia. Give at least 30-45 minutes prior, to desired effect. Use only in young, healthy animals. Causes hypotension.


Dexmedetomidine

Dose: 2-10 µg/kg
Route: SQ/IM/IV
Comments: A profound drop in heart rate may result. Can be reversed with the same volume of Atipamezole as the volume of Dexmedetomidine used.


Midazolam

Dose: 0.2-0.4 mg/kg
Route: IM/IV


Acepromazine + Butorphanol

Dose: Acepromazine: 0.005-0.060 mg/kg + Butorphanol: 0.1-0.4 mg/kg
Route: IV/SQ/IM


Midazolam + Butorphanol

Dose: Midazolam: 0.10-0.20 mg/kg + Butorphanol: 0.1-0.40 mg/kg
Route: IM/IV

Induction

Induction

Induction refers to an anesthetic administered to place an animal in an unconscious state and allow for tracheal intubation.


Propofol

Dose: 4 to 6 mg/kg in unmedicated animals; 1 to 4 mg/kg in premedicated/sedated animals
Route: IV
Comments: Slowly deliver titrated volume, as rapid administration will lead to apnea and hypotension. Very rapid onset and recovery. Propofol is a respiratory depressant. Animals receiving propofol should be intubated following administration of induction dose. Causes hypotension when given as a bolus.


Isoflurane

Dose: 2-4%
Route: Inhalation
Comments: Given to effect.

Maintenance

Maintenance

Maintenance refers to drugs administered to keep animals unconscious and allow for surgical (or other) procedures to be performed.

Parenteral administration: For parenteral administration of maintenance anesthesia, the intravenous (IV) route is almost always used.

Endotracheal intubation: Inhalation anesthesia may be delivered by a facemask, but is generally delivered via endotracheal intubation.

  • Dogs can be intubated using a laryngoscope.
  • Endotracheal tube sizes for 25-kg dogs are generally between 7.5 and 9 mm. When attempting intubation, have several sizes available and ready with appropriate ties.
  • Applying sterile surgical lubricant to the tip of the endotracheal tube will help facilitate intubation.
  • The endotracheal tube should extend approximately from outside the mouth to the thoracic inlet. This can be used as a guide for how far the tube should be inserted upon intubation. 
  • Verify proper placement of the endotracheal tube by ausculting all lung fields for strong breath sounds. If no breath sounds are heard, back the tube out until sounds are heard in all lung fields. 
  • Endotracheal tubes need to have a cuff, and cuffs need to be inflated during anesthesia. Inflate the cuff just enough to stop gas leakage. Over-inflation of the endotracheal tube cuff can damage the trachea.

Gas anesthesia machines: Facemasks and intubation require gas anesthesia machines with an oxygen source and a precision vaporizer. For animals weighing more than 5 kg, use a rebreathing system.

Gas scavenging systems: When using inhalant anesthesia, use an anesthetic system equipped with a gas scavenging system to minimize occupational exposure to exiting gases.

Ophthalmic ointments: For anesthetic events lasting greater than five minutes and whenever facemasks are used, apply an ophthalmic ointment (e.g., Paralube® or Lacrilube®) to eyes to prevent corneal drying and trauma.


Isoflurane

Dose: 1-2% maintenance
Route: Inhalation
Comments: Given to effect.


Propofol – Constant rate infusions (CRI)

Dose: 0.05-0.4 mg/kg/minute
Route: IV
Comments: Begin CRI after initial induction dose. Animals receiving propofol should be intubated, as it is a respiratory depressant.

References for these guidelines are available by request.