A clinical-grade nutritional powder incorporating Green Lipped Mussel, designed to help combat age-related muscle loss (sarcopenia) and support joint health in cats.

Muscle loss matters in cats too: studies link declining muscle mass with age, and lower body weight at CKD diagnosis is associated with markedly higher mortality risk. A University of Florida study (ACVIM Forum, 2021) found Fortetropin safe and well tolerated in cats, with no greater frequency of mild adverse events than placebo.

• Fortetropin — enhances protein synthesis and maintains healthy muscle mass, reducing muscle loss from aging, injury or inactivity.
• Green Lipped Mussel — a natural source of Omega-3 fatty acids to help reduce inflammation and stiffness, with Glycosaminoglycans (GAGs) that support joint flexibility and comfort. Especially valuable for arthritic patients.

Muscle Loss Is Behind More Cases Than You Think

Sarcopenia (age-related muscle loss), post-surgical atrophy, and reduced mobility in arthritic patients all share a common thread: loss of lean muscle. Muscle isn't just about strength — it underpins mobility, recovery, metabolic health and longevity. Yet it's one of the few areas most clinics have no dedicated product to address.

MYOS closes that gap with Fortetropin — a clinically-studied, all-natural ingredient with a clear mechanism of action and real trial data behind it.

How Fortetropin Works
Fortetropin is a bioactive protein made from fertilised chicken egg yolk using a patented, high-pressure pasteurised process. It works by reducing circulating myostatin — the body's signal to break muscle down — while supporting the pathways that build muscle up (upregulating mTOR activity and downregulating the ubiquitin-proteasome breakdown pathway).

The result: muscle is preserved and rebuilt more efficiently, supporting recovery, mobility and vitality.

The Clinical Evidence

• Post-Operative Muscle Protection - In a randomised, double-blind, placebo-controlled study of 100 dogs recovering from TPLO surgery, daily Fortetropin significantly reduced muscle atrophy compared with a macronutrient-matched placebo.
• Increased Muscle Protein Synthesis - In a randomised, double-blind, placebo-controlled human study of older adults (60–75 years), daily Fortetropin increased the rate of muscle protein synthesis by roughly 18% versus placebo.
• Safe & All Natural - Steroid-free, free from fillers and artificial additives, and sourced from fertilised chicken egg yolk.
• Good Manufacturing Practice - MYOS adheres to Good Manufacturing Practice (GMP) standards for consistent quality and safety across all their products.
• NASC Member - MYOS is a member of the NASC (National Animal Supplement Council), committed to providing health supplements of the highest quality for companion animals.