Clinical Studies

Completed Research



Kansas State University: Fortetropin resulted in decreased Liverpool Osteoarthritis in Dogs’ (LOAD) scores in geriatric dogs. Read study


Kansas State University:  Fortetropin® prevented atrophy of disuse and improved recovery from TPLO surgery. Read study


University of Tampa:  Fortetropin acts by upregulating mTOR pathway (promoting muscle growth), downregulating Ubiquitin pathway (slowing muscle degradation), and lowering myostatin levels (promoting muscle growth). Read study


University of Florida: Safety and tolerability in healthy cats. Read abstract


University of California, Berkeley: Fortetropin increased rate of muscle protein synthesis by 18% in older adults. Read study


McMaster University: In a study involving the unilateral leg immobilization model in young men, Fortetropin supplementation prevented a rise in serum myostatin levels. Read study


North Carolina State University: Study showed that Fortetropin supplementation increased lean muscle mass in 70 percent of cats while contributing no adverse side effects. See Poster Presentation Below.


The Impact of Fortetropin on Safety and Tolerability in Retired Horses. Read White Paper










As pets age, quality of life and mobility can be impacted by pain of osteoarthritis and age-related muscle atrophy (sarcopenia). The purpose of this randomized, double-blinded, placebo controlled study was to evaluate the effects of Fortetropin®, a nonthermal-pasteurized, freeze-dried, fertilized egg yolk product, on mobility in senior dogs. Mobility scores were calculated using a standardized and validated client-based survey, the Liverpool Osteoarthritis in Dogs (LOAD) questionnaire. Results showed mild, but statistically significant, improvement of the mobility scores for the treatment group at both week 6 (p= 0.03) and week 12 (p= 0.006) compared to the baseline score. No statistical improvement was noted at any time point in the placebo group or between the treatment and placebo group.



Hetrick, Katie, Kenneth R. Harkin, and James K. Roush. "Evaluation of Fortetropin in geriatric and senior dogs with reduced mobility." The Canadian Veterinary Journal= La Revue Veterinaire Canadienne 63.10 (2022): 1057-1060.

International Expert on Canine Osteoarthritis, Michael H. Jaffe, DVM, MS, CCRP, DACVS, Associate Professor, Mississippi State University College of Veterinary Medicine reviewed the study and believes that Fortetropin should be used as part of a multimodal strategy to address canine osteoarthritis.


"Osteoarthritis in dogs is one of the most common orthopedic conditions seen in veterinary practice. Multimodal management, with few surgical options, is the mainstay of its treatment. To combat the ongoing problem of generalized muscle atrophy due to aging and reduced pet mobility, this paper focuses on an aspect of treatment that has largely been minimally addressed. To minimize sarcopenia, and thus improve patient mobility, treatment by reduction of serum myostatin levels with Fortetropin® showed promise compared to a nutritionally similar control.

Hetrick et al demonstrate a statistically significant improvement in owner assessed (LOAD) mobility scores after 6 and 12 weeks of treatment compared to a placebo supplement. Based on studies such as this, it is my opinion that use of products that inhibit myostatin levels to reduce sarcopenia, such as Fortetropin®, should be considered a valuable component of multimodal management for the treatment of canine osteoarthritis." Professor Jaffee.













To determine if a commercial myostatin reducer (Fortetropin®) would inhibit disuse muscle atrophy in dogs after a tibial plateau leveling osteotomy.


A prospective randomized, double-blinded, placebo-controlled clinical trial. 


One hundred client-owned dogs presenting for surgical correction of cranial cruciate ligament rupture by tibial plateau leveling osteotomy.


Patients were randomly assigned into the Fortetropin® or placebo group and clients were instructed to add the assigned supplement to the dog’s normal diet once daily for twelve weeks. Enrolled patients had ultrasound measurements of muscle thickness, tape measure measurements of thigh circumference, serum myostatin level assays, and static stance analysis evaluated at weeks 0, 8, and 12.


From week 0 to week 8, there was no change for thigh circumference in the Fortetropin® group for the affected limb (-0.54cm, P = 0.31), but a significant decrease in thigh circumference for the placebo group (-1.21cm, P = 0.03). There was no significant change in serum myostatin levels of dogs in the Fortetropin® group at any time point (P>0.05), while there was a significant rise of serum myostatin levels of dogs in placebo group during the period of forced exercise restriction (week 0 to week 8; +2,892 pg/ml, P = 0.02). The percent of body weight supported by the affected limb increased in dogs treated with Fortetropin® (+7.0%, P<0.01) and the placebo group (+4.9%, P<0.01) at the end of the period of forced exercise restriction. The difference in weight bearing between the Fortetropin® and placebo groups was not statistically significant (P = 0.10).


Dogs receiving Fortetropin® had a similar increase in stance force on the affected limb, no significant increase in serum myostatin levels, and no significant reduction in thigh circumference at the end of the period of forced exercise restriction compared to the placebo. These findings support the feeding of Fortetropin® to prevent disuse muscle atrophy in canine patients undergoing a tibial plateau leveling osteotomy.



White, Dana A., et al. "Fortetropin inhibits disuse muscle atrophy in dogs after tibial plateau leveling osteotomy." PLOS ONE 15.4 (2020): e0231306. 









To evaluate the effect of a single administration of 6 and 12 g of Fortetropin compared to placebo on serum myostatin in healthy, adult dogs over a 72-h period.


Prospective, placebo-controlled, randomized, double-blind, crossover study. Ten hospital-employee-owned healthy adult dogs aged 2 to 8 years old were enrolled in the study. Blood samples were collected prior to and then 12-, 24-, 36-, 48-, and 72-h following administration of the test agent (6 and 12 g) or placebo. Serum samples were processed according to manufacturer’s guidelines for canine serum using GDF-8/Myostatin Quantikine ELISA kit (R&D Systems). Analysis-of-variance (ANOVA) analyses were carried out where P < 0.05 was deemed significant.


Mean serum myostatin was not significantly lower in treatment groups of either low or high dose compared to placebo at any time point. Baseline mean serum myostatin in low and high dose treatment groups was 29,481 (SD = 5,224) and 32,214 pg/mL (SD = 7,353), respectively. Placebo group low and high dose baseline mean serum myostatin was 30,247 (SD = 5,875) and 28,512 (SD = 5,028).


The results of this study indicate that administration of single 6 or 12 g dose of Fortetropin does not reduce serum myostatin in healthy adult dogs.

Clinical Importance: Oral supplements, like Fortetropin, require further studies to determine the efficacy and bioavailability in order to guide clinical use in dogs.


The Impact of Fortetropin® in Cats Suffering from Chronic Kidney Disease


This study was conducted at the North Carolina State University College of Veterinary Medicine and showed that Fortetropin supplementation increased lean muscle mass in 70 percent of test subjects while contributing no adverse side effects. The study was presented at the 2023 AAVN Clinical Nutrition and Research Symposium, Philadelphia, PA.


CKD study