Senior Diet Deep Dive
and an update...
This week one of our older family dogs went to the vet for a consultation. After an exam and blood tests, she recommended a low-protein diet. Since this is the opposite of how we think senior dogs should eat we did a deep dive.
Before that we wanted to give you an update. We’ve been on break from our regular scheduled content, but we haven’t been on vacation (we wish). Instead we’ve been working on our upcoming full length book. Our goal is to make this the best ever book in this space. The manuscript is finished and we are doing some final edits before it goes to the copy editor. A big thank you to those who voted on the title. The Dog’s Table is scheduled to hit shelves in December of this year. (Yes, traditional publishing takes that long!) Here are some behind-the-scenes pictures of production.
TLDR: AAFCO does not publish guidelines for senior dogs, so vet recommendations and manufacturer’s formulations are highly variable. Vets and many companies recommend low-protein diets, however, based on our research we DO NOT recommend low protein, high-carbohydrate diets for healthy seniors. High-carbohydrate diets strain the pancreas and kidneys far more than high-protein diets.
Senior Diets
One of our family dogs, Rocky, is getting really old. He’s a long-haired black and tan Dachshund, but is almost the polar opposite of Cedric. Calm and relaxed, Rocky just chills, while Cedric can’t sit still. A couple years ago, at age 13, Rocky’s health started to decline. He had recurrent diarrhea and bloody bowel movements. His teeth were infected and had to get pulled, he was in a lot of pain. Our family mistakenly believed that he couldn’t eat anything other than dog food without getting sick. After a lot of cajoling, we managed to get him off kibble and onto a whole food diet.
Within a few months the diarrhea went away and he started running again. Since switching him to real food, Rocky has had no digestive issues. He went from a “sensitive dog” to being able to eat pretty much anything.
Recently, Rocky went for a check up and teeth cleaning. His blood tests showed elevated kidney markers which is common in older dogs. The vet suggested he switch to a low-protein “renal” diet. This didn’t sound right to us at all, but because she was a vet, our immediate instinct was to question ourselves, despite the thousands of hours we put into researching this newsletter.
Turns out that there is no real evidence to support the use of low-protein diets to delay the onset of kidney disease in senior dogs. Most of the studies that manufacturers use to support their diets are comparing varying formulations of kibble, WHICH ARE ALL HIGH-CARBOHYDRATE. Our formulations would be impossible to make into kibble because of the low carbohydrate content. Here’s what we think healthy seniors should have for macronutrients:
>50% calories from fat, about 35% calories from protein, and
<15% carbohydrate (Rocky will now go to <10% carbohydrate)
Why do some vets recommend low-protein senior diets?
Because AAFCO does not publish senior dog feed guidelines, many manufacturers distinguish themselves by creating proprietary and “prescription” diets. We’ve previously written on the deceitful tactics some brands employ.
Because kibble requires about 40% calories from carbohydrate to work in extrusion machines, manufacturers can only meaningfully reduce fat or protein in their formulations, but not carbohydrate. Since there are only three macronutrients, any reduction in one leads to increases in the others. In other words, low-protein diets must have higher fat or carbs, while low-carb diets must have higher fat or protein. Our research indicates that low-protein diets, especially those with high carbs are not supportive of renal health for senior dogs. In fact, quite the opposite.
To our knowledge, there has not been a well controlled study in senior dogs testing renal function with a low-carbohydrate diet. However, one controlled study showed that a diet of high-quality proteins with fruits, vegetables and fish oil temporarily reversed the age-associated decline in renal function compared to a low-protein commercial renal diet.
Why do dogs need more protein but lower carb as they age?
When an animal consumes protein, cells get a signal that they can start producing new proteins to do things, called protein synthesis. Some proteins help animals to move, like muscles. Other proteins do things in cells, like hemoglobin that moves oxygen around the body. As animals age they become less sensitive to this signaling. Researchers estimate that young animals have 2-3 times the protein synthesis rate of old animals. This leads to conditions like sarcopenia, the age-associated loss of muscle in older dogs and people. For this reason, seniors need to consume more protein than young animals for a similar level of function.
Carbohydrates, however, work on a different pathway—insulin. Insulin is a hormone produced by the pancreas that signals cells to start absorbing glucose. Because carbohydrates break down into glucose, which is primarily used as a fuel source, it’s either burned as energy or stored, usually as fat, in healthy animals. As animals age they become insulin resistant, so the pancreas has to work harder to produce more insulin for the same effect. But because carbohydrates and glucose are non-essential nutrients for both dogs and people, we do not technically NEED them. In moderation they are great.
Sugar is what actually taxes the kidneys and pancreas
“[The urine of diabetics] is wonderfully sweet as if it were imbued with honey or sugar” Dr. Thomas Willis, 1674
Before modern diagnostics, doctors would sometimes taste the urine of patients to diagnosis diabetes. As gross as this sounds it was actually really effective. Healthy dogs and people don’t pee out glucose because we evolved in nutrient poor environments. Sugar was extremely valuable, so we developed all sorts of ways to recapture and store it.
Kidneys are an amazing organ and play a role in managing glucose levels and blood pressure, but most importantly they remove waste from the blood. Interestingly, rather than filtering out the bad stuff, kidneys actually reabsorb all of the things we need, including glucose. Everything else is discarded as urine.
When a dog or person has a lot of glucose in the blood, the kidneys can’t reabsorb it fast enough and the sugar spills into the urine. High levels of glucose in the blood and urine are not just bad for the kidneys and pancreas, it’s particularly damaging to small blood vessels like those in the eyes, feet, brain and heart. For this reason, diabetics with uncontrolled blood sugar sometimes require amputation of extremities and can suffer blindness.
What about fat?
We’ve written a lot about how dogs’ preferred fuel source is fats. Working dogs seem to benefit the most from high-fat diets. Studies show increased activity levels when pups are fed ultra low-carb diets. Racing dogs, conversely, are slower when fed low-carb diets. Carbohydrates help to give them top end speed and athleticism.
Some vets (not the good ones) attribute pancreatitis to high fat diets, but the literature suggests that this isn’t true. (As discussed above, it’s high carbohydrates that stress the pancreas the most, not fats.) Fats, especially a mix of different fats from plants, animals and fish, are great for pups and people alike.
That’s it for this week. We hope you’re having a great start to your year!
All the best,
Joelle and The Precious Creatures Team
Would love more senior recipes and senior advice! This is a fantastic analysis. There has been more studies showing humans need more protein as we age, esp. women.