If you've been researching lignans for your dog's Cushing's disease, you've probably run into two terms: SDG and HMR. Both are used to manage Cushing's naturally. Both have a track record. And they're not the same thing.
Here's a plain-English breakdown of how they differ, when one has an advantage over the other, and what most owners end up choosing.
What SDG Lignans Are
SDG (secoisolariciresinol diglucoside) lignans are extracted from the hulls of flaxseeds — the outer layer that's removed when flaxseed is processed. They're the most widely studied form of lignans for canine Cushing's disease, and the dosing protocol most commonly cited by integrative veterinarians is built specifically around them: 1 -2 mg of SDG per pound of body weight, once daily.
When a dog digests SDG, gut bacteria convert it into active compounds (enterolactone and enterodiol) that interact with the hormonal system. This conversion step is one reason probiotics can enhance lignan effectiveness — healthy gut bacteria do more of the converting work.
What HMR Lignans Are
HMR (7-hydroxymatairesinol) lignans come from the knots of Norwegian spruce trees. They're highly bioavailable, meaning the active compound is absorbed more directly without the same level of gut conversion required by SDG.
Dosing for HMR lignans is the same as SDG; being 1-2mg per pound of body weight.
How They're Similar
Both types work by influencing the body's steroid hormone pathway, helping moderate cortisol overproduction. Survey data from owners managing Cushing's naturally shows similar response rates between the two forms — approximately 85% of lignan users report improvement in at least one Cushing's symptom within two months, regardless of which type they used. Both are safe for long-term use and well tolerated.
How They're Different
The main practical differences:
· SDG requires gut bacteria to activate — dogs with compromised digestion or recent antibiotic use may not convert it as efficiently
· HMR is more directly bioavailable and doesn't rely on gut conversion
· SDG carries a higher antioxidant load overall
· HMR comes from a different plant source, which matters if your dog has flaxseed sensitivities
Which Should You Choose?
For most dogs, either works well. A few scenarios where one has an edge:
Choose SDG if your dog has a healthy digestive system, you're already giving probiotics (which enhance conversion), and you prefer a weight-based dosing protocol that scales precisely.
Choose HMR if your dog has had recent antibiotic treatment, has a history of digestive issues, or you simply prefer a flat-dose format that doesn't require weighing.
Some owners use both. There's no known interaction, and the protocols complement each other.
A Note on Atypical Cushing's
If your dog has been diagnosed with atypical Cushing's — the sex hormone-driven form rather than cortisol-driven — SDG lignans may have a specific advantage due to how they interact with steroid hormone metabolism.
More on natural Cushing's management: Cushings In Dogs — Holistic Treatment Options
For a list of all our lignans products, click here.
Sources:
• University of Tennessee College of Veterinary Medicine — Treatment Considerations