Selegiline (L-deprenyl)
Sold as Anipryl
The only approved drug for canine dementia. Worth trying, particularly for disrupted sleep and lost house-training, but set expectations modestly and pair it with a diet change and enrichment rather than relying on it alone.
Why this grade
Selegiline is the only FDA-approved drug for canine cognitive dysfunction and is the pharmaceutical most often reached for in practice, but the controlled trial base is older, smaller, and less rigorously reported than the modern MCT diet trial. The reported benefits of improved sleep, house-training, and activity come from trials that predate current validated cognitive scoring instruments. C reflects limited rather than absent evidence, not a judgment that it fails.
What the trials show
Clinical trials supporting approval showed improvement in sleeping, house-training, and activity in treated dogs. A 2025 survey of US practice found that when clinicians manage cognitive dysfunction pharmacologically, selegiline is the drug most often recommended, reflecting its unique approval status as much as its measured effect size. The trials underpinning it are not directly comparable to the modern multi-site randomized dietary work, because they used earlier outcome measures and smaller samples; anyone claiming a clean head-to-head between selegiline and an MCT diet is overstating what exists.
Harms and cautions
Generally well tolerated. Vomiting, diarrhea, restlessness, and agitation occur. The important issue is drug interactions: as a monoamine oxidase inhibitor, selegiline must not be combined with other MAO inhibitors including amitraz, and combination with certain antidepressants, opioids such as tramadol, or serotonergic drugs risks serotonin syndrome. Review the entire medication list, because geriatric dogs are frequently on several drugs at once.
Practical detail
- Route
- Oral, once daily in the morning
- Typical course
- A trial of 4-8 weeks is reasonable before judging response; some dogs need up to 2 months
- Monitoring
- Score cognition with a validated instrument at baseline and at follow-up; review all concurrent medications for serotonergic interactions before starting
- Cost
- moderate
Regulatory status
- United States
- FDA-approved 10 December 1998 for canine cognitive dysfunction syndrome, the only drug with that indication. Also approved for pituitary-dependent hyperadrenocorticism.
- Note
- Regulatory approval here reflects an older evidentiary era. Approval status and evidence strength are not the same thing, in either direction.
Questions worth asking your vet
- Do any of my dog's current medications interact with an MAO inhibitor?
- How long should we give this before deciding it has not worked?
- Should we run this alongside an MCT diet and enrichment rather than as a standalone?
- Have we excluded pain, sensory loss, and endocrine disease as the real driver of these behavior changes?
The evidence, one study at a time
FDA approval of selegiline hydrochloride (Anipryl), NADA 141-096, approved 10 December 1998 for control of clinical signs associated with canine cognitive dysfunction syndrome.
regulatory 1998
The basis for the only drug approval in this indication. Older trials with outcome measures that predate today's validated cognitive scales.
- Design
- Registration clinical trials
- Blinding
- unclear
- Control
- Placebo
- Result
- Improvement reported in sleeping, house-training, and activity.
- Funding
- Manufacturer
Current practices for diagnosis and management of Canine Cognitive Dysfunction Syndrome in the United States. Frontiers in Veterinary Science, 2025.
observational 2025
Describes what practitioners do, which is not the same as what the evidence establishes. Included to make that distinction explicit.
- Design
- Practice survey
- Blinding
- not-applicable
- Result
- Selegiline is the pharmaceutical most often recommended by US clinicians managing canine cognitive dysfunction.