Ketamine is primarily used in dogs as an anesthetic for surgery and as a pain management tool during and after procedures. It belongs to a class called dissociative anesthetics, meaning it creates a trance-like state where the dog is disconnected from pain sensation while maintaining certain protective reflexes. Veterinarians also increasingly use it at much lower doses to control severe or hard-to-treat pain.
How Ketamine Works in Dogs
Ketamine’s main job is blocking a specific type of receptor in the brain and spinal cord called the NMDA receptor. When these receptors are active, they amplify pain signals, sometimes creating a feedback loop where the nervous system becomes increasingly sensitive to pain. Ketamine is one of the most potent blockers of this receptor available in clinical medicine, and this blocking ability works even at doses far below what’s needed for full anesthesia.
At higher doses used for anesthesia, ketamine also interacts with opioid receptors throughout the body. This combination of effects is what makes it useful both as an anesthetic and as a standalone pain modifier. At lower doses, it acts primarily in the spinal cord, where it interrupts the exaggerated pain responses that can develop during and after surgery.
Surgical Anesthesia
The most common reason your vet will use ketamine is to induce anesthesia before a surgical procedure. It’s rarely given alone. Instead, it’s typically paired with a sedative to smooth out the experience and reduce side effects. A standard combination is ketamine with diazepam (Valium), given intravenously to bring the dog into a surgical plane of anesthesia quickly and safely.
One reason ketamine is popular for induction is its effect on the cardiovascular system. Unlike many anesthetics that drop blood pressure, ketamine stimulates the release of stress hormones that keep heart rate and blood pressure stable or even slightly elevated. This makes it a useful choice for dogs that are in shock, dehydrated, or otherwise at risk of dangerous blood pressure drops during anesthesia. The trade-off is that this cardiovascular stimulation means ketamine isn’t ideal for every patient, particularly dogs with certain heart conditions.
Pain Control During and After Surgery
Beyond putting dogs under for surgery, ketamine has become an important tool for managing surgical pain. Veterinarians use it as a continuous low-dose drip (called a constant rate infusion) that runs through an IV line during the procedure and often for hours afterward. A typical protocol starts with a small initial dose before the first incision, a moderate drip rate during surgery, and then a lower rate for up to 18 hours after the procedure ends.
The goal of this approach is to prevent a phenomenon called central sensitization, sometimes described as “wind-up pain.” When tissues are cut or damaged during surgery, the spinal cord can become hypersensitive, amplifying pain signals beyond what the actual injury warrants. By keeping a steady, low level of ketamine flowing during and after the procedure, the vet blocks this wind-up process before it starts. Dogs treated this way often need less additional pain medication during recovery.
Chronic and Difficult-to-Treat Pain
Ketamine is sometimes used for dogs with chronic pain that hasn’t responded well to standard treatments, including osteoarthritis. There are no formally established protocols for this use in veterinary medicine, and published research remains limited. However, some veterinary pain specialists use short infusions lasting 4 to 24 hours at low doses to reset the nervous system’s pain sensitivity. Others have reported success with small injections given under the skin on a weekly or biweekly basis for dogs with severe joint pain.
This type of use falls outside ketamine’s standard label and is considered more experimental. If your vet suggests it, they’re drawing on principles well established in human pain medicine, where low-dose ketamine infusions are a recognized treatment for chronic pain conditions.
Side Effects and Recovery
The most notable side effect of ketamine in dogs is a phenomenon called emergence delirium. As the drug wears off, some dogs go through a period of confusion and agitation. Signs include restlessness, psychomotor agitation, hyperexcitability, escape behaviors, lack of eye contact, and seeming completely unaware of their surroundings. The dog may thrash or move without purpose. This looks alarming but is a recognized and usually self-limiting phase of recovery.
Veterinary staff manage rough recoveries by keeping the environment calm with dimmed lights and quiet voices, using gentle restraint, and in more severe cases, administering a small dose of sedative to smooth the transition. Pairing ketamine with a sedative at the time of anesthesia reduces the likelihood of emergence delirium in the first place, which is one of the main reasons ketamine is almost never used alone.
On the cardiovascular side, ketamine tends to raise heart rate and blood pressure in the first few hours after administration. In healthy dogs, this is generally well tolerated and resolves on its own.
When Ketamine Should Be Avoided
Ketamine causes a clinically significant increase in pressure inside the eye. Because of this, it should not be used in dogs with glaucoma, corneal injuries, or those undergoing eye surgery. Dogs with elevated pressure inside the skull, such as those with head trauma or brain masses, are also poor candidates because ketamine can worsen intracranial pressure.
Dogs with a history of seizures require careful evaluation, as ketamine’s stimulating effects on the nervous system can be problematic. Your vet will weigh the risks and benefits based on your dog’s specific health profile and choose an alternative anesthetic if ketamine poses too great a risk.
Ketamine as a Controlled Substance
Ketamine is classified as a controlled substance by the DEA, which means veterinary clinics must follow strict storage and record-keeping rules. Clinics are required to keep detailed logs for every dose dispensed, store the drug in a locked safe, and maintain records for a minimum of two years (longer in some states). This classification reflects ketamine’s potential for misuse outside of medical settings, but it does not change its safety profile when administered by a veterinarian in a clinical setting. If your vet uses ketamine for your dog’s procedure, this regulatory framework is already being followed behind the scenes.