This page is an educational reference for veterinarians and veterinary students. It does not replace a thorough examination, clinical judgment, or the attending veterinarian's final decision. Doses are for adult animals, per kilogram; the amount and volume of each drug for a patient, and the doses for neonates and seniors, are calculated in the tool itself.
Step by step
per kilogram of body weight
1 Preanesthetic preparation Before the injection
Healthy animal: allow free access to water; withhold food for 4–6 hours before anesthesia.2
Animal under 8 weeks or under 2 kg: withhold food for no more than 1–2 hours, monitor blood glucose before, during and after induction, and schedule it as the first patient of the day.2
Animal with a history or risk of regurgitation: withhold food and water for 6–12 hours.2
Vomiting is common with dexmedetomidine; pretreatment with an antiemetic such as maropitant reduces it.2,3
The low end of the range gives only moderate sedation and is not enough for intubation or surgery. For these, use the high end of the range with an opioid; if that is still not enough, complete the anesthesia with an IV induction agent or an inhalant, not with more dexmedetomidine.1,4,5
Draw it up with ketamine in one syringe and give it as a single IM injection; the two drugs are compatible.1,6
The low end of the range of both drugs is for moderate sedation, and the high end for deep sedation to light anesthesia.1
Give a nervous, aggressive or excited animal time to settle before the injection.6
In dogs, the dexmedetomidine dose is sometimes slightly lower.1
Effects of this drug
Produces sedation and analgesia; their depth and duration depend on the dose.3,6
Less anesthetic is needed; with ketamine, muscle relaxation and the quality of recovery improve.6,7
Lowers heart rate and cardiac output and constricts peripheral vessels; mucous membranes may look pale or bluish even though arterial oxygenation is normal.3,6
Vomiting is common, usually 5–10 minutes after injection; more common in cats and at higher doses.3,6
Its effects, including analgesia, are reversed by atipamezole.7,8
3 Induction With dexmedetomidine, in the same syringe
Ketamine provides poor visceral analgesia: for visceral surgery (such as abdominal surgery), use this combination with an opioid.1,9
Give it with dexmedetomidine in the same syringe as a single IM injection. An IM dose cannot be given in small increments to effect.1
IM ketamine is painful; expect the animal to react.3,10
Effects of this drug
Produces analgesia and amnesia; muscle tone and pharyngeal and laryngeal reflexes are partly preserved.10
Somatic analgesia (skin, muscle, bone) is good, but visceral analgesia is poor.9
Raises heart rate, blood pressure and cardiac output. Respiratory depression increases with the dose, and apnea has been reported, especially in cats.10
On its own it causes muscle rigidity; with a sedative such as dexmedetomidine, muscle relaxation is better and the effect lasts longer.7,10
Place the endotracheal tube as soon as possible; pharyngeal and laryngeal reflexes are partly preserved, but they do not protect the airway.1,10
Once anesthetized, give oxygen to every animal; hypoxemia is common with this combination. Monitor breathing and heart rate regularly.6,11
The eyes stay open and the cornea may become opaque: apply a corneal lubricant ointment or drops and repeat every 2–4 hours.1,6,10
In cats, the larynx goes into spasm when stimulated: before intubation, drip no more than 0.2 mL of 2% lidocaine without epinephrine onto the arytenoid cartilages from a 1 mL syringe without a needle, and wait 60–90 seconds with oxygen. A spray with a nozzle may damage the laryngeal mucosa.3
In cats, if laryngospasm occurs, stop, give oxygen and check the depth of anesthesia; wait 60–90 seconds before trying again. Laryngospasm usually resolves on its own.3
6 Anesthesia 10–20 minutes
A single injection of ketamine usually provides 10–20 minutes of anesthesia; dexmedetomidine prolongs the effect, and the duration depends on the dose.7,10
At a lower dose or without an opioid, the effect is shorter and lighter. For a longer procedure, have an inhalant ready; do not inject dexmedetomidine again.6,7,12
In cats, at the high end of the range with an opioid, anesthesia usually lasts 15–30 minutes.7
7 Recovery Usually up to 2 hours
Let the animal recover in a calm, quiet place.8,10
Keep the animal warm; give no food or water until it can swallow.6
Full recovery from ketamine usually takes up to 2 hours, sometimes longer.10
In dogs, excitement and vocalization are sometimes seen during recovery.10
In dogs, do not routinely reverse this combination with atipamezole. If the effects of dexmedetomidine become life-threatening, give atipamezole IM at 10 times the amount of dexmedetomidine given; its volume equals the volume of dexmedetomidine 0.5 mg/mL and is one-fifth the volume of dexmedetomidine 0.1 mg/mL.6,8
In cats, excitement or hyperactivity may be seen during recovery.7
In cats, if needed, reverse dexmedetomidine with atipamezole IM, but routinely no sooner than 45 minutes after ketamine; earlier, the remaining effect of ketamine may cause seizures. If the effects of dexmedetomidine become life-threatening, give atipamezole sooner and be ready for seizures. The analgesia of dexmedetomidine is reversed too.6,8,10
In cats, the atipamezole amount is 5 times the amount of dexmedetomidine given; with atipamezole 5 mg/mL, its volume is one-tenth the volume of dexmedetomidine 0.1 mg/mL and half the volume of dexmedetomidine 0.5 mg/mL.8
Options in this protocol
Opioid (optional)
For surgery or a painful procedure, choose an opioid for the same syringe.
No opioidFor procedures that do not need strong analgesia
The percentage on each side is not a measurement but a qualitative grade from the sources: full 100, good 75, partial 50, low 25, none zero. It refers to the peak effect after induction, not the whole duration.
HypnosisLoss of consciousness — 75% (Good)
The low end of the range produces moderate sedation, and the high end deep sedation to light anesthesia.1
Dexmedetomidine enhances and prolongs the effect of ketamine, and less anesthetic is needed.6,10
AnalgesiaPain control — 50% (Partial)
Dexmedetomidine provides analgesia and is used for procedures with mild to moderate pain.6
Ketamine provides good somatic but poor visceral analgesia.9
The analgesia of dexmedetomidine lasts about 1 hour, shorter than its sedation; without an opioid, analgesia is not enough for surgery.1,12
Muscle relaxationRelaxed muscle tone — 75% (Good)
At the peak effect of dexmedetomidine, the animal is relaxed and recumbent and does not respond to external stimuli.6
Alpha-2 agonists produce muscle relaxation even at low doses.12
A sedative given with ketamine improves muscle relaxation; ketamine alone causes muscle rigidity.7,10
Blood pressure: First high, then normal or low
In dogs, this combination may raise blood pressure and lower the heart rate.6,11
In cats, blood pressure may rise first and then fall; the heart rate falls.4,6
Dexmedetomidine ↑↓ Rises, then falls: Raises blood pressure first, then brings it back to normal or below; slows the heart rate.6
Contraindication Do not give dexmedetomidine in: cardiovascular disease, severe systemic disease, moribund animals, or hypersensitivity to the drug.6
Contraindication Do not give ketamine in: severe heart failure, suspected lung disease, hypertension, cerebrovascular injury, liver or kidney disease, eclampsia, glaucoma, seizures or epilepsy, myelography, or hypersensitivity to the drug. Surgery of the pharynx, larynx, trachea or bronchi without adequate muscle relaxation and intubation is also contraindicated.10
Cautions and notes
Caution For surgery or a painful procedure, also choose an opioid: dexmedetomidine's analgesia lasts about 1 hour, and ketamine's visceral analgesia is poor.1,9,12
Caution By the IM route, the dose cannot be given in small increments to effect, and the airway cannot be secured quickly. Watch the animal closely until it is anesthetized; have intubation equipment and oxygen ready, and give oxygen if the animal is calm.1
Caution This combination is for healthy animals. In sick or debilitated animals, give dexmedetomidine only after weighing the risks and benefits; in moderate disease, IV induction is preferred.1,6
Caution Give atropine or another anticholinergic with dexmedetomidine with caution; blood pressure may rise very high.3,6
Caution Monitor body temperature and keep the animal warm during anesthesia and recovery.6
Caution Do not inject dexmedetomidine again; for a longer procedure, maintain anesthesia with an inhalant.6,7
Caution Dexmedetomidine is not recommended during pregnancy and lactation; do not give ketamine near parturition.6,10
Caution In dogs, this IM technique is mainly for very small dogs or fractious, aggressive dogs; in medium and large dogs, the IM injection volume is large. If the dog is calm and IV access is possible, IV induction is better.1
Note Dexmedetomidine and ketamine are compatible and can be drawn up in one syringe; the mixture remains compatible for at least 2 hours.6
Caution In cats, part of the ketamine is excreted unchanged by the kidneys; use caution in kidney failure.1