Is there help for dogs suffering from age-related muscle atrophy?
Muscle atrophy is the gradual loss/wasting of the dog’s muscle tissue. It is, unfortunately, common in senior dogs. Age-related muscle atrophy affects especially the hind legs. In fact, any weakness issue shows up in the hind end first.
Non-age-related causes of muscle atrophy include:
- injuries
- surgery
- illness and disease
- reduced activity due to pain and other reasons
- disuse such as crate rest
- muscle inhibition
Symptoms of muscle atrophy include:
- progressive hind end weakness
- ataxia
- abnormal gain and posture
- difficulty getting up
- weight loss/muscle thinning
Further reading: Muscle Atrophy in Dogs: What It Is, How to Spot It and Fix It
Senior dogs can lose muscle mass both to normal processes related to aging or joint and other issues.
Cookie’s story
Cookie is a spayed Rottweiler female and she turned ten at the beginning of March. Cookie has been a vigorously active girl all her life. She enjoys exploring, tracking, rodent, and frog hunting. Cookie has had her share of injuries and health issues. However, we’ve been managing them. Her enthusiasm is her worst enemy.
For a couple of years I noticed that after digging after a mouse, Cookie’s hind legs got tired. It didn’t surprise me—she’d spend prolonged time in unnatural and challenging positions.
It wasn’t until last year that the issue became more pronounced and began spilling to other activities. Cookie also started having a harder time rising from her bed.
Neither Cookie’s veterinarian nor physical therapist found any obvious issues and the veterinarian diagnosed it as age-related muscle wasting.
What now?
Even though I cannot let her do as much, Cookie is still quite active and has a strong prey drive. I am trying to balance her psychological and physiological needs. She gets chiropractic care and physical therapy.
It was Cookie’s physical therapist who brought a new canine supplement to my attention—MYOS Canine Muscle Formula.
I am attracted to the fact that it’s a natural supplement. However, I am also skeptical because it is so new.
MYOS Canine Muscle Formula
Cookie’s physical therapist and I are looking into whether this supplement would be beneficial to Cookie.
The single ingredient in MYOS muscle formula is Fortetropin®. If you’ve never heard of it—don’t feel bad—neither have I.
What is Fortetropin®?
Fortetropin is a proteo-lipid complex made from fertilized egg yolk. Sounds quite yummy.
Proteolipid
Proteoipid is a macromolecule made of protein and fat molecules.
According to the manufacturer, Fortetropin® is a formula derived from fertilized chicken egg yolks. It is designed to build muscle and reduce muscle loss due to aging or injury.
Further reading: About Fortetropin®
What does Fortetropin do?
It appears that Fortetropin is a myostatin reducer that inhibits muscle atrophy.
Myostatin
Myostatin is a type of cytokine, a cell-signaling molecule. Cytokines are involved in controlling the growth and activity of immune cells and blood cells.
Myokines, specifically, regulate skeletal muscle mass and function.
Myostatin is a myokine that regulates/restrains muscle growth. Everything in the body needs to be in balance—too much muscle would be just as bad as too little.
Further reading: Role of Myokines in Regulating Skeletal Muscle Mass and Function
But what if there is already too little muscle mass—could myostatin improve the status quo?
For example, a study of dogs after TPLO surgery showed that inhibiting myostatin reduced disuse muscle atrophy. According to the study, the post-op exercise restrictions significantly increased myostatin levels, leading to muscle loss. Dogs who were treated with Fortetropin had no muscle loss.
Further reading: Fortetropin inhibits disuse muscle atrophy in dogs after tibial plateau leveling osteotomy
In other words, it appears that disuse leads to an increase in myostatin levels and muscle wasting and it can be prevented by supplementing Fortetropin.
It would make sense. Muscle maintenance requires huge resources and the body won’t maintain muscle that is not in use. The two main compounds involved in the regulation of muscle growth are insulin and insulin-like growth factor and myostatin. Myostatin is the muscle down-regulator.
Fortetropin®
Dvm360 speaks positively about the effect of the supplement used for TPLO post-op.
The supplement Fortetropin has been shown to curb muscle atrophy associated with postoperative exercise restriction in dogs following surgical repair of cruciate tears.
Joan Capuzzi, VMD
Does that mean it would help dogs with age-related muscle wasting too?
Mayo Clinic would agree that lowering myostatin protects muscle from wasting;
- Myostatin inhibition, even partial reductions, increases muscle mass in adult and older mammals.
- Myostatin’s effects are highly specific to muscle mass.
- Disrupting myostatin signaling may also positively affect multiple other age-associated changes, including increased bone mineral density, improved cardiac ejection fraction, and resistance to diet-induced obesity, dyslipidemia, atherogenesis, hepatic steatosis, and inflammation.
- Myostatin is a highly druggable protein because it is secreted and accessible in circulation.
Further reading: Slowing or reversing muscle loss
Muscle mass versus muscle strength
One study of concern I found tested the complete removal of myostatin in mice. According to the study, the myostatin-deficient mice had larger muscle mass. However, their muscles were weaker. for their size. That could be a concern. There is not much point to having bigger muscle that is weaker.
Overall, our results suggest that lack of myostatin compromises force production in association with loss of oxidative characteristics of skeletal muscle.
Lack of myostatin results in excessive muscle growth but impaired force generation
On the other hand, in the study the mice were void of myostatin completely. The question is whether reduction would have the same, however lower, effect as complete elimination. Further, the above study is from 2007.
Human papers highlight some potential side effects of myostatin inhibition including:
- tendon injuries
- heart inflammation
- breakdown of muscle fibers leading to kidney failure
Like with everything, side effects might be dose-dependent. The other question might be whether there is a difference between long- and short-term use. For example, the TPLO study featured short-term supplementation.
Asking vets
I asked around what professionals I trust think about it. Many haven’t heard of it. Cookie’s vet feels quite positively about it after making her own inquiry.
I had not heard of this product so I consulted our specialty forum to see what the surgeons and rehab vets think of the product. There are both positive and negative studies in terms of results, but many of the specialists are trying it anyway.
It’s a high protein high fat supplement, and the orthopedic surgeons like it post surgery as an adjunct to physio.
There is a bit of a wink and a nod that whole eggs may produce a similar effect, but by and large the experts agree that it doesn’t do any harm unless the patient has renal disease.
So most are giving it a try and seeing how it goes anecdotally – and there are some very positive reviews from rehab vets.
Bottom line—no harm in trying and I’d be interested in your results if you choose to go ahead.
Another veterinary friend of mine, Dr. Dan, is considering trying it for his senior dog. However, he has similar concerns to mine.
Dr. Julie Buzby has used it for some of her patients and feels that clinically it works. She gives it thumbs up.
Jasmine’s vet looked into it and asked what he calls “people smarter than him.” He feels that it’s a interesting product with impact down the road but needs work. He figured that muscle growth with lack of strength might be from lack of innervation. He thinks that it might be useful in improving existing normal muscle.
PT perspective
Cookie’s physical therapist is interested in the product. After all, she’s the one who brought it to my attention.
I asked my friend PT Sue. She has seen some decent results, She estimates 60:40 anecdotal success rate in her patients. However, she strongly recommends combining the supplement with strengthening exercises.
In closing
There is a reason for caution with any new product. At this time, I am leaning toward trying it short term and going from there.
Are you familiar with Fortetropin®? Have you tried it for you dog? What are your thoughts?
Further reading;
Frailty Syndrome in Geriatric Dogs: Physical Therapy and Home Care to Reverse Frailty
Product website:
Myospet
Further reading:
Disuse muscle atrophy inhibited by nutritional supplement
Fortetropin inhibits disuse muscle atrophy in dogs after tibial plateau leveling osteotomy
Lack of myostatin results in excessive muscle growth but impaired force generation