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Dean Pomerleau

Dog CR - What Every Pet Owner and CR Practitioner Should Know

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Over on this thread, Rodney wrote:

 

[My dog Paloma ("dove" in mexican)] insists on sniffing every garbage bag in sight to check if it has a chicken bone or pork rib (prohibited items in dog CR!) inside it.

 

Have you decided whether or not to actually calorie restrict Paloma?

 

I restrict my dog Zoe, and that's one reason I suspect she is always scrounging for food as well.

 

Specifically, I limit her food to 80g/day, about 10% below the 90g/day recommended on the package for active dogs her size (11lbs) - she gets a lot of exercise for a small dog since she runs around while my wife and I walk her > 3 miles per day, which is  long way for a small dog.

 

From the dog food package, that amount of dog food equates to about 28 kcal / lb of bodyweight per day. If scaled to a 115lbs person like me - that would be about 3200 kcal/day, which is quite close to what I eat, when you factor in metabolizable energy!

 

Interestingly, this 28kcal / lb BW per day is exactly the same amount of food fed to the control group of Labradors in the dog CR studies [1][2] that Al posted about recently, conducted by the Ralston Purina company about a decade ago.

 

Unfortunately, the poor Labs were likely pretty sedentary, kept in cages their entire lives, without opportunity to take walks   :(xyz. From [1]:

 

  Dogs were housed in 2 X 19-m indoor-outdoor kennel runs with concrete floors for 8 years. The amount of exercise the dogs received was not controlled.

 

According to the package on our dog food, relatively sedentary dogs should get only 66% as many calories as active dogs (e.g. 60g/day instead of 90g/day for a dog Zoe's size, or 18.66 kcal / lb BW per day).

 

Plus, to make things even worse for the poor caged & sedentary Labs, the control dogs were fed ad lib from weaning until age 3.25 years - over 1/4 of their entire lifespan. Labs are fully grown and are supposed to have reached their adult weight by 2 years old, so the control dogs were fed ad lib until well into adulthood.

 

In contrast, each CR dog was paired with one of the control dogs (of the same gender - 2/3rd were female), and fed 25% less than their pair-mate from weaning until death, so 25% less than ad lib for the first 3.25 years, and 21 kcal / lb BW per day - which is still above the 18.66kcal/lb BW recommended for sedentary dogs!

 

The fact that they were fed ad lib until well past maturity, and likely had a sedentary lifestyle and so were overfed throughout their life by usual dog calorie recommendations, is reflected in the control dogs' weight. They don't have the weight trajectory data for the dogs, but by the 8th year the control dogs weighed an average of 74 lbs, which is 40% more than the CR dogs, who weighed 53 lbs on average.

 

From here, the healthy weight range for female Labs (since these were mostly females) is 55-70 lbs. I'm not sure what the definition of obesity would be for relatively sedentary Labradors, but the control dogs were above the healthy weight range, and the CR dogs were right around the bottom end of the healthy range. So the control group might be the equivalent of about a human BMI of 26-27 (overweight but not quite obese) and the CR group would be around a human BMI equivalent of 18-18.5, right around many CR practitioners. Rapid growth and too much weight is bad news for dogs (and for people), but especially for Labs, because they are prone to cancer and especially joint problems / osteoarthritis, which is exacerbated by too much food and/or too much weight.

 

So what were the lifespan results? From [2], the CR dogs lived 17% longer on average compared to the control dogs (13 vs. 11.1 years mean lifespan). The longest lived dog was a CR female, who died at 14.5 years, which was 9% longer than the longest lived control dog, another female who lived to 13.29. So not a whole lot of difference in max lifespan.

 

While not in the original paper [1], I've created a graph of the survival curves for the two groups of dogs from Table 1 in the full text (yes - call me crazy). Here it is:

 

R5OJ3E8.png

 

Given how few dogs there were in each group (only 24), those survival curves are amazingly smooth and well-behaved!

 

They also bear a striking resemblance to the AL and 10% CR groups of rats in PMID 26695614 that I discussed here two days ago, the survival graph from which I've reproduced below: 

 

chmDHdg.png

 

If you ignore the CR40 survival curve, the two remaining rat survival curves (AL and CR10) look a whole lot like those of the two dog groups. Recall in that study, the median survival of the CR10 rats was 14% longer, and the median survival of the CR40 rats was 19% longer than AL-fed controls. In the dogs, the CR25 survival advantage was 17% relative to controls, right in the middle. Amazingly consistent!

 

Given the striking similarity between the dog and the rat data, it would seem reasonable to extrapolate the dog data to predict that if there had been a CR10 group of dogs, they would have enjoyed a small bit less life extension relative to the CR25 dogs (e.g.. ~14% median life extension vs. 17% for CR25), and if there had been a CR40 group of dogs, they might have enjoyed a small bit more life extension relative to the CR25 dogs (e.g. ~19% vs. 17% median life extension for CR25).

 

Put another way - the control dogs in this study were fed too much, given their caged lifestyle, so they grew fat. The CR dogs were fed an amount commensurate (or a bit higher) than is recommended by dog nutrition experts, remained slim and lived 17% longer than controls, enjoying nearly as much CR longevity benefit as can be hoped for in mammals, based on the rat data from PMID 26695614 discussed here

 

Bottom line? It appears from the rat, dog and primate CR data, that most of the CR benefits for the average animal come from avoiding overweight/obesity. Severe CR appears to provide seriously diminishing (perhaps negligible) marginal returns in terms of median lifespan, and may come at the cost of increased early mortality (based on the aforementioned rat data), and IMO probably not worth the risk given the disappointing 9% max lifespan advantage seen in the CR25 dogs relative to overweight controls.

 

So my plan for myself and Zoe is to remain very active and eat only enough to stay quite slim. That way we both may be able to garner some CR benefits, and perhaps I at least can remain in good health long enough to be around for the arrival of longevity escape velocity, hopefully in several decades if we're lucky.

 

Zoe is 5 years old. While her breed (Havanese) is long-lived for dogs (typically 13-15 years), she is unlikely to be around long enough to live forever. Perhaps I'll clone her or cryopreserve her, if either technology improves and comes down in price quickly enough.  :)xyz

 

--Dean

 

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[1] J Am Vet Med Assoc. 2000 Dec 1;217(11):1678-80.

 
Evaluation of the effect of limited food consumption on radiographic evidence of 
osteoarthritis in dogs.
 
Kealy RD(1), Lawler DF, Ballam JM, Lust G, Biery DN, Smith GK, Mantz SL.
 
Author information: 
(1)Pet Nutrition Research Department, Ralston Purina Company, St Louis, MO 63164,
USA.
 
 
OBJECTIVE: To determine prevalence of radiographic evidence of osteoarthritis in 
4 diarthrodial joints of dogs with restricted feed intake, compared with dogs
without restricted feed intake.
DESIGN: Paired feeding study.
ANIMALS: 48 Labrador Retrievers.
PROCEDURE: Dogs in litters from 7 dams and 2 sires were paired by sex and weight 
within litters and randomly assigned to a control-fed group or a limit-fed group 
that received 25% less food than the control-fed group. Radiographic evaluation
of prevalence and severity of osteoarthritis in the hip, shoulder, elbow, and
stifle joints was performed when dogs were 8 years of age.
RESULTS: Radiographic evidence of osteoarthritis that affected multiple joints
was significantly more common in the control-fed group than in the limit-fed
group. Prevalence of lesions in the hip joint was 15/22 in the control-fed group 
and 3/21 in the limit-fed group. Prevalence of lesions in the shoulder joint was 
19/22 in the control-fed group and 12/21 in the limit-fed group; lesions in this 
joint were generally mild. Severity, but not prevalence, of osteoarthritis in the
elbow joint was greater in the control-fed group than in the limit-fed group.
CONCLUSIONS AND CLINICAL RELEVANCE: Prevalence and severity of osteoarthritis in 
several joints was less in dogs with long-term reduced food intake, compared with
control dogs. Food intake is an environmental factor that may have a profound
effect on development of osteoarthritis in dogs.
 
PMID: 11110459
 
--------------
[2] J Am Vet Med Assoc. 2005 Jan 15;226(2):225-31.

Influence of lifetime food restriction on causes, time, and predictors of death
in dogs.

Lawler DF(1), Evans RH, Larson BT, Spitznagel EL, Ellersieck MR, Kealy RD.

Author information:
(1)Néstle Purina PetCare Research, 835 S 8th St, St Louis, MO 63164, USA.

 

Free full text: https://www.avma.org/News/Journals/Collections/Documents/javma_226_2_225.pdf

OBJECTIVE: To describe effects of lifetime food restriction on causes of death
and the association between body-mass characteristics and time of death in dogs.
DESIGN: Paired-feeding study.
ANIMALS: 48 dogs from 7 litters.
PROCEDURES: Dogs were paired, and 1 dog in each pair was fed 25% less food than
its pair mate from 8 weeks of age until death. Numerous morphometric and
physiologic measures were obtained at various intervals throughout life.
Associations of feeding group to time and causes of death were evaluated, along
with important associated factors such as body composition components and
insulin-glucose responses.
RESULTS: Median life span was significantly longer for the group that was fed 25%
less food, whereas causes of death were generally similar between the 2 feeding
groups. High body-fat mass and declining lean mass significantly predicted death
1 year prior to death, and lean body composition was associated with metabolic
responses that appeared to be integrally involved in health and longevity.
CONCLUSIONS AND CLINICAL RELEVANCE: Results were similar to results of diet
restriction studies in rodents and primates, reflecting delayed death from
species- and strain-specific intrinsic causes. Clinicians should be aware that
unplanned body mass changes during mid- and later life of dogs may indicate the
need for thorough clinical evaluation.

PMID: 15706972

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Ola, Dean:

 

"Have you decided whether or not to actually calorie restrict Paloma?"  Tentatively yes.  But there are several obstacles that will make it more complicated:  A)  I do not live in the same region year round so the same foods are not consistently available;  B)  She gets tired of most foods quickly, so will not eat them if they have been available more than a few days;  C)  Some of the commercial dog foods she seems to like do not appear to show calorie counts.  But I assume I will be able to get those data from the manufacturer; D)  Similarly to some other dogs, Paloma must be fed food she really likes every evening, otherwise she wakes up around 3am and will scream down the entire neighborhood if I do not take her outside so she can eat grass!

 

"I limit Zoe to 80g/day, about 10% below the 90g/day recommended on the package for active dogs her size (11lbs) - she gets a lot of exercise for a small dog."   TYVM for all the data.

 

Paloma is estimated to be about 20 months of age (based on tooth development), but was starved on the street, probably for several months, before I acquired her twelve months ago.  She now has much more hair than when I got her.  Previously, her hair was so sparse you could clearly see the beige and black shading of her skin color through her hair.   So I figure she is probably only now fully grown in all material respects.  I have measured her waist size - 14" at the smallest circumference - and her original weight was 4.95 kg.  I estimate she weighs a little more now.  So I plan to stabilize her dimensions at the current level, and start to restrict few months down the road.

 

20 months in the life of a dog that might be expected to live 17 years, unrestricted on a very healthy diet, is the equivalent of 8.8 years in the life of a human expected to live to the age of 90 under similar circumstances (not forgetting life expectancy has been increasing by one-fifth of a year per year).  But of course dogs become fertile at six months, whereas in humans development is proportionally a lot slower, so comparisons of this type are not realistic.  Nevertheless delaying restriction for a while is unlikely to cause harm, and starting too early very possibly might, as Kaplan-Meier curves of this type of data always seem to show.

 

I much appreciate all your data on this.  I will update if I have useful input to contribute as the months go by.

 

Rodney.

 

==========

 

"The unverified conventional wisdom is almost invariably mistaken."

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I do some sort of IF on my dog. Some days 250g or a single bird carcass and other days up to 500g. I keep him quite lean. He only gets coarsely ground meat or carcasses. I am too unsure of the quality of regular dog chow. I figured if you do CR you also got to do the ON. As far as I know the risks of raw dog meat are for me due to contamination, but not for him.

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All,

 

While serious CR may not do any more than a healthy, obesity-avoiding diet to help your dog live a long time (see top post in this thread), it does appear diet quality can make a difference, at least in certain breeds. This case-control study of Scottish Terriers [1] (popular press article) found that those dogs who ate fresh green leafy vegetables or orange/yellow vegetables at least 3 times per week were 70-90% less likely to to have bladder cancer (which apparently strikes a lot of Scottish Terriers) than dogs who didn't eat their veggies. Interesting, neither cruciferous vegetables nor a multivitamin supplement appears to have much of a protective effect.

 

 We've been feeding our dog Zoe a high quality dry dog food, and discouraging her incessant attempts to eat grass - perhaps a misguided instinct to add more veggies to her diet ☺. I'm going to add some cut carrots and leafy greens to her diet based on this study.

 

--Dean

 

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J Am Vet Med Assoc. 2005 Jul 1;227(1):94-100.
 
Evaluation of the effect of dietary vegetable consumption on reducing risk of
transitional cell carcinoma of the urinary bladder in Scottish Terriers.
 
Raghavan M(1), Knapp DW, Bonney PL, Dawson MH, Glickman LT.
 
Author information: 
(1)Department of Veterinary Pathobiology, School of Veterinary Medicine, Purdue
University, West Lafayette, IN 47907-2027, USA.
 
OBJECTIVE: To evaluate the effects of vegetable consumption and vitamin
supplementation on the risk of developing transitional cell carcinoma (TCC) of
the urinary bladder in Scottish Terriers.
DESIGN: Case-control study.
ANIMALS: 92 adult Scottish Terriers with TCC (cases) and 83 Scottish Terriers
with other conditions (controls).
PROCEDURE: Owners of dogs with TCC completed a questionnaire regarding their
dogs' diet and intake of vitamin supplements in the year prior to diagnosis of
TCC; owners of control dogs completed the questionnaire for a comparable time
period. The risk (odds ratio [OR]) of developing TCC associated with diet and
vitamin supplementation was determined by use of logistic regression.
RESULTS: After adjustment for age, weight, neuter status, and coat color, there
was an inverse association between consumption of vegetables at least 3 times/wk 
(OR, 0.30; 95% confidence interval [CI], 0.15 to 0.62) and risk of developing
TCC. For individual vegetable types, the risk of developing TCC was inversely
associated with consumption of green leafy vegetables (OR, 0.12; 95% CI, 0.01 to 
0.97) and yellow-orange vegetables (OR, 0.31; 95% CI, 0.14 to 0.70). Consumption 
of cruciferous vegetables was not significantly associated with a similar
reduction in risk of developing TCC (OR, 0.22; CI, 0.04 to 1.11). The power of
the study to detect a 50% reduction in TCC risk associated with daily vitamin
supplementation was considered low (25%).
CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that consumption of certain
vegetables may prevent or slow the development of TCC in Scottish Terriers.
 
PMID: 16013542

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In the past I (over)fed my dogs conventionally on commercial dog foods and they died at ages ranging from 8 to 12 years.  And all 3 by cancer.

 

Now I have a 6 year old, 17 lb rat terrier who so far is in excellent health.  We feed her a small amount of premium commercial dogfood as an accent to whatever I cook for her.  We keep hens so she gets a fresh egg almost every day and she also gets a little of whatever I'm having which in the past included a lot of carbs, such as potatoes, rice and whole grain breads, vegetables and fruit and a little meat and cheese, but now has a lot more vegetables without the carbs and so far she seems good with the change.

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