The dog who scratches at nothing

Doges Editorial · 2026-06-08 · 5 min read

For decades, a painful neurological condition in dogs — most common in Cavalier King Charles Spaniels — was often dismissed as allergies or anxiety. In May 2026, the FDA conditionally approved the first drug specifically designed to treat it.

The dog scratches the air beside its own neck. Not the skin — the air. The paw moves in the same arc it would to reach an itch, but there is nothing there. No flea, no burr, no rash. It happens most often while walking on a leash, or when the dog gets excited, or sometimes just because the weather changed. The dog might yelp for no visible reason. It might slow down on a walk, fall sideways, straighten, and keep going. Owners, for years, have been told to check for ear infections, skin conditions, allergies — the usual suspects.

What they are often watching is syringomyelia: a fluid-filled cavity forming inside the cervical spinal cord, caused by the skull being slightly too small for the brain inside it. The condition, formally called Chiari-like malformation and syringomyelia (CM/SM), has long been one of the most underdiagnosed sources of chronic pain in dogs. And in May 2026, for the first time, it has a drug specifically built to treat it.

The condition that hides in plain sight

CM/SM is most common in small and toy breeds, and the rates in Cavalier King Charles Spaniels have alarmed breed health researchers for decades. Research by neurologist Clare Rusbridge and colleague Susan Knowler found that 70% of Cavaliers showed syringomyelia on MRI by age six, with just 13% clear of both the malformation and the fluid cavities in the spinal cord. Researchers estimate that as many as 95% of the breed carry the underlying skull malformation — so prevalent that some scientists describe it as an inherent feature of the breed standard.

Data from the Royal Veterinary College's VetCompass program, which tracks health records across thousands of UK practices, found one in every 60 Cavaliers receives a formal diagnosis of symptomatic syringomyelia — equating to roughly 2,000 dogs in Britain affected at any given time. Of those formally diagnosed, 72% had pain recorded in their veterinary notes: yelping, flinching, or avoidance of touch around the neck and head.

The symptoms are strange enough to mislead. A dog that yelps while being picked up might be written off as dramatic. One that hesitates before jumping on the sofa might be getting older. One that starts moving with a slight curve to its body, or that seems to walk with an uneven gait, might be sent to an orthopedic specialist. The air-scratching — what neurologists call phantom scratching — is the most distinctive sign, but it takes an experienced eye to recognize it for what it is rather than some quirk of the individual dog.

What the FDA just approved

On May 12, 2026, the U.S. Food and Drug Administration conditionally approved Liavium-CA1 — pregabalin chewable tablets — for the management of pain and clinical signs associated with CM/SM in dogs. The product was developed by TriviumVet, an Ireland-based company acquired by Pegasus Laboratories in 2025, and it is the first drug to receive FDA approval specifically for this indication.

Pregabalin, the active ingredient, works by reducing the release of neurotransmitters responsible for sending pain signals through the spinal cord — a mechanism already used to manage nerve-related pain in humans. Liavium-CA1 comes as beef-flavored chewable tablets in 30 mg, 90 mg, and 180 mg strengths, given orally twice daily with food. It is prescribed for dogs weighing between 6.6 and 50 pounds.

Liavium-CA1 signals a turning point in canine pain management by providing veterinarians a first-of-its-kind option.

— Dr. Heather Davis, Senior Director of Medical Affairs, Pegasus Laboratories

What the clinical evidence showed

The FDA's conditional approval pathway is reserved for drugs treating serious or life-threatening conditions, where demonstrating effectiveness requires particularly complex studies. The reasonable expectation of effectiveness for Liavium-CA1 was based on a published randomized controlled trial in Cavalier King Charles Spaniels with MRI-confirmed syringomyelia and clinical signs of central neuropathic pain.

The results were striking. Compared to placebo, pregabalin produced an 84% reduction in phantom-scratching episodes, with a 95% confidence interval of 75 to 89% (p < 0.0001). Owner-assessed quality of life was rated 'good' or 'could not be better' in six of eleven dogs assessed, with a further four showing improvement. The most common adverse effects were increased appetite and transient ataxia — brief coordination difficulties that resolved without intervention.

The conditional approval means the FDA has determined Liavium-CA1 is safe and has a reasonable expectation of effectiveness for its intended use.

— U.S. Food and Drug Administration, May 12, 2026

Why this matters beyond the Cavalier community

Veterinarians have been managing CM/SM for years with a patchwork of off-label tools: gabapentin (a related neuropathic pain drug), diuretics and antacids intended to reduce cerebrospinal fluid pressure, corticosteroids, and in some cases acupuncture as an adjunct. None of these were developed or approved specifically for this condition. Liavium-CA1 is the first product where a regulatory agency has looked at the evidence for CM/SM specifically and said: this works, and here is how.

TriviumVet has up to five years to complete the additional effectiveness studies needed to convert the conditional approval into a full one. In the meantime, the drug is available by prescription from licensed veterinarians — who are required not just to prescribe it, but to confirm the diagnosis through MRI or other neurological assessment. CM/SM cannot be diagnosed by looking at a dog. It requires imaging.

Recognizing the signs

The condition often shows itself on walks first. A Cavalier that slows more than usual, that begins the arching sideways scratch while moving, that seems reluctant to engage with the leash — these are things owners notice before they have a name for them. Pain that increases with exercise or excitement is consistent with CM/SM. So is sensitivity around the neck and ears, yelping when picked up, or a reluctance to climb stairs that came on gradually.

Paying attention to the ordinary

Most dogs with CM/SM are not in constant crisis. They have good days and bad ones. A walk in cold weather might trigger an episode that a walk in mild air does not. Excitement — the same excitement that makes a dog nearly knock you over at the front door — can set off a scratching bout that clears on its own within a minute. Owners who track their dogs' walks, who notice that Monday's route felt heavier than Wednesday's, who've learned the difference between their dog's 'exploring' pace and their 'something's off' pace, are often the ones who catch these patterns first.

The phantom scratch is called phantom because the pain generating it is real, but its source is neurological — not something the dog can reach, not something that goes away when they scratch. Recognizing it, naming it, and now treating it: that trajectory took more than two decades from the first documentation of the condition in Cavaliers. May 2026 was the month the trajectory reached a treatment shelf.