It is one of the most common questions we hear from owners: “My dog is already on trilostane — can I still give lignans and melatonin, or do I have to choose?” It is a good question, and an important one, because mixing anything with a Cushing’s medication deserves care. Here is a plain-English answer, along with the reasoning behind it.
First, What Trilostane Does
Trilostane (brand name Vetoryl) is the most common prescription treatment for Cushing’s disease in dogs. It works by blocking an enzyme the adrenal glands use to make cortisol, lowering cortisol for a number of hours after each dose. It is effective, and for many dogs it is the backbone of treatment — but it requires regular monitoring so the dose stays in the safe, effective range.
What Lignans and Melatonin Do
Lignans and melatonin take a gentler, different route to a similar goal. Research from the University of Tennessee suggests they inhibit some of the same hormone-producing enzymes in the adrenal gland, helping to ease the hormonal excess behind Cushing’s signs. Because they act through their own mechanism rather than duplicating trilostane exactly, many owners are drawn to them either as a starting point before medication or as added support alongside it.
Can They Be Used Together?
According to the University of Tennessee’s treatment guidance, it is considered acceptable to give flaxseed lignans to a dog that is already taking trilostane or mitotane (Lysodren). In other words, lignans and melatonin are generally viewed as compatible with conventional Cushing’s medication rather than something you must stop first. That is reassuring for owners who want to support their dog as fully as possible.
There is an important nuance, though. Because both trilostane and the lignan/melatonin combination work to lower cortisol-related activity, your veterinarian will want to know everything your dog is taking so that monitoring and dosing account for the whole picture. This is teamwork, not a workaround.
Why Some Owners Combine Them
Owners choose to add lignans and melatonin to trilostane for a few reasons: to support atypical Cushing’s features that involve adrenal sex hormones, to feel they are doing everything reasonable for a beloved dog, or as part of a longer-term plan discussed with their vet. Others use lignans and melatonin first, and only move to trilostane if signs are not controlled. There is no single right path — it depends on your dog, the type of Cushing’s, and your veterinarian’s guidance.
The One Rule That Matters Most
Whatever you decide, do not change your dog’s trilostane dose on your own, and do not add supplements silently. Tell your veterinarian exactly what you are giving and keep up with the scheduled monitoring (bloodwork and cortisol checks). Trilostane is a drug that needs its dose kept in a careful window; your vet can only manage that safely if they have the full picture. If your dog ever becomes unusually tired, stops eating, or has vomiting or diarrhea, pause and call your vet — those can be signs cortisol has dropped too low.
The Bottom Line
Yes — lignans and melatonin can generally be given alongside trilostane, and the University of Tennessee’s guidance supports doing so. The essential step is to make it a shared decision with your veterinarian, so your dog’s treatment is monitored as one coordinated plan rather than two separate ones.
Sources
- University of Tennessee College of Veterinary Medicine — Treatment Option Considerations for Hyperadrenocorticism in Dogs (PDF). vetmed.tennessee.edu
- Oliver JW, et al. “Effect of combined lignan phytoestrogen and melatonin treatment on secretion of steroid hormones by adrenal carcinoma cells.” Am J Vet Res. 2011;72(5):675. avmajournals.avma.org
- MSPCA-Angell — Trilostane Dosing and Monitoring in Dogs. mspca.org