Tramadol's Rise in Veterinary Medicine
For a period of roughly two decades, tramadol was one of the most commonly prescribed pain medications in small animal veterinary practice. It was considered a useful, relatively affordable, and reasonably safe option for managing moderate pain in dogs — particularly post-operatively, and in cases of chronic pain from conditions like osteoarthritis or cancer. Vets prescribed it routinely, owners gave it at home, and it seemed like a sensible part of the analgesic toolkit.
Then the research caught up with clinical practice, and the picture became considerably more complicated. Today, tramadol occupies a much more nuanced position in veterinary medicine — still used in some contexts, but with significant caveats that have fundamentally changed how vets think about it for canine patients.
How Tramadol Is Supposed to Work
Tramadol is classified as an atypical opioid. In humans, it works through two main mechanisms: it binds to mu-opioid receptors in the central nervous system to reduce pain perception, and it inhibits the reuptake of serotonin and noradrenaline — neurotransmitters involved in modulating pain signals. Together, these actions produce an analgesic effect that has been well-documented in human medicine.
The assumption for many years was that this same mechanism would translate to dogs. It does not — at least not in the same way. The problem lies in how dogs metabolise tramadol. The active analgesic metabolite of tramadol in humans is O-desmethyltramadol (M1), which has a much stronger affinity for opioid receptors than the parent compound. Dogs convert tramadol to M1 very poorly and very slowly compared to humans, meaning the opioid component of tramadol's action is substantially diminished in canine patients.
What the Research Actually Shows
Multiple studies published from the mid-2010s onwards began to seriously question whether tramadol provided meaningful analgesia in dogs. A landmark study published in 2015 in the journal Veterinary Surgery compared tramadol, carprofen, and placebo in dogs with osteoarthritis and found no significant difference between tramadol and placebo on objective measures of pain and mobility. Carprofen, by contrast, showed clear benefit.
Subsequent pharmacokinetic studies confirmed what the clinical research was suggesting: the plasma concentrations of M1 achieved in dogs following oral tramadol administration are far below what would be needed for clinically meaningful opioid receptor activation. The serotonin and noradrenaline reuptake inhibition does still occur, and this may provide some modest benefit — but it is not the robust analgesic effect that was originally assumed.
This does not mean tramadol does nothing in dogs. It means it probably does considerably less than was believed, and significantly less than it does in humans and cats.
Tramadol in Cats: A Different Story
It is worth noting that the situation in cats is quite different. Cats produce M1 at higher levels than dogs, and tramadol has been shown to provide meaningful analgesia in feline patients. It is used for acute pain management and as part of post-operative protocols in cats, and the evidence base for its use in this species is considerably stronger than it is for dogs.
This species difference is a useful reminder that veterinary pharmacology cannot be generalised across animals. A drug that works well in one species may be ineffective or dangerous in another, and the history of tramadol in dogs illustrates why species-specific research matters.
Is Tramadol Still Used in Dogs?
Yes — but the indications have narrowed considerably. In some countries and practices, it continues to be used as part of multimodal pain management, particularly where the goal is to target the serotonergic component of pain modulation rather than opioid receptor activation. It may have a role in managing neuropathic or central pain, where altering neurotransmitter reuptake might offer some benefit independent of the opioid mechanism.
It is also still used in contexts where other options are unavailable, cost-prohibitive, or contraindicated. In dogs where NSAIDs cannot be used due to kidney disease or gastrointestinal concerns, and where access to stronger opioids is limited, tramadol may represent a pragmatic if imperfect choice.
In the United States, tramadol's status changed in 2014 when it was placed on Schedule IV of the Controlled Substances Act, making it more tightly regulated and adding administrative burden to its prescription. This has contributed to a decline in its use in some practices. In the UK and Europe, regulations differ, but prescribing habits have still shifted as the evidence base has matured.
What Should Replace Tramadol in Canine Pain Management?
For dogs with chronic pain from osteoarthritis, the current evidence strongly supports NSAIDs as the cornerstone of treatment, alongside weight management, physiotherapy, and environmental modification. Gabapentin is a well-supported adjunct for neuropathic pain. Newer options such as the monoclonal antibody bedinvetmab, which targets nerve growth factor to reduce osteoarthritis pain, are showing considerable promise.
For acute and post-operative pain, true opioids such as buprenorphine, methadone, and fentanyl — used under veterinary supervision and appropriate controlled drug regulations — offer far more reliable analgesia than tramadol. Local anaesthetic techniques and regional nerve blocks are also increasingly incorporated into surgical pain protocols.
The lesson of tramadol in dogs is not that the medication is harmful — it is relatively well-tolerated — but rather that assumed efficacy based on human data is not a reliable foundation for veterinary prescribing. Dogs are not small humans, and the pharmacological tools we reach for to manage their pain need to be chosen on the basis of evidence developed specifically in canine patients. The good news is that the evidence base for canine pain management has grown substantially, and there are better-supported options available than ever before.