Lifetime 25% diet restriction paired-feeding study in 48 Labrador Retrievers
Forty-eight Labrador Retrievers from seven litters were paired by sex and weight, and one dog in each pair was randomly assigned to receive 25% less food than its control-fed pair mate from 8 weeks of age until death. Median life span was significantly longer in the diet-restricted dogs (1.8 years longer), and the onset of clinical signs of chronic disease, especially osteoarthritis, was delayed. Diet restriction also retarded age-related declines in lymphoproliferative responses and lymphocyte subsets and did not negatively affect skeletal maturation, while elbow osteoarthritis prevalence and severity did not differ between feeding groups.
Record
| Design | randomized controlled trial |
|---|---|
| Status | completed |
| Intervention | 25% diet restriction (each restricted dog fed 75% of the food consumed by its control-fed pair mate; same diet, only the quantity differed) |
| Intervention class | diet restriction |
| Comparator | Control-fed (CF) pair mate |
| Dose regimen | 25% less food than the pair-mate (75% of the total food consumed by the control-fed pair mate); feeding began at age 8 weeks |
| Duration | From 8 weeks of age until death (lifetime); body composition measured annually until 12 years of age; immune parameters monitored from 4 to 13 years |
| Dogs | 48 |
| Population note | 48 dogs from seven litters, paired at 6 weeks by sex and weight and allotted to 2 groups of 24 (diet-restricted and control-fed) |
| Breed | Labrador Retriever |
| Age | Paired at age 6 weeks; feeding protocol from 8 weeks of age until death |
| Other | Puppies from 7 litters; weight- and sex-matched pairs |
| Primary outcome | Life span (median: age when 50% of dogs deceased; maximum: age when 90% deceased), age at onset of chronic disease, and markers of aging (serum biochemistry, body condition, body composition) |
| Result (as reported) | Median life span was significantly longer for dogs in which food was restricted (1.8 years longer median lifespan among diet-restricted dogs), and the onset of clinical signs of chronic disease generally was delayed, especially osteoarthritis. CR retarded age-related declines in lymphoproliferative responses and lymphocyte subsets. No differences in prevalence or severity of radiographic and histopathologic elbow OA were found between feeding groups; long-term DR did not negatively affect skeletal maturation, structure or metabolism. |
| Tags | diet-restriction, lifespan, labrador-retriever, immunosenescence, osteoarthritis, body-composition |
Notes: Four papers report one lifetime study: the 2002 JAVMA results paper, the 2006 immunosenescence sub-analysis, the 2008 two-decade review and the 2009 elbow osteoarthritis sub-analysis. The abstracts do not name the sponsoring organization, the housing setting or the calendar years; the slug follows the registry's working name for the study.
Sources and verbatim quotes
Effects of diet restriction on life span and age-related changes in dogs. (2002) PMID 11991408 (results)
To evaluate the effects of 25% diet restriction on life span of dogs and on markers of aging.
Paired feeding study.
48 Labrador Retrievers.
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.
Serum biochemical analyses were performed, body condition was scored, and body composition was measured annually until 12 years of age.
Age at onset of chronic disease and median (age when 50% of the dogs were deceased) and maximum (age when 90% of the dogs were deceased) life spans were evaluated.
Compared with control dogs, food-restricted dogs weighed less and had lower body fat content and lower serum triglycerides, triiodothyronine, insulin, and glucose concentrations.
Median life span was significantly longer for dogs in which food was restricted.
The onset of clinical signs of chronic disease generally was delayed for food-restricted dogs.
Results suggest that 25% restriction in food intake increased median life span and delayed the onset of signs of chronic disease in these dogs.
Diet restriction and ageing in the dog: major observations over two decades. (2008) PMID 18062831 (follow-up)
This report reviews decade two of the lifetime diet restriction study of the dog.
Labrador retrievers (n 48) were paired at age 6 weeks by sex and weight within each of seven litters, and assigned randomly within the pair to control-feeding (CF) or 25 % diet restriction (DR).
Feeding began at age 8 weeks. The same diet was fed to all dogs; only the quantity differed.
Major lifetime observations included 1.8 years longer median lifespan among diet-restricted dogs, with delayed onset of late life diseases, especially osteoarthritis.
Long-term DR did not negatively affect skeletal maturation, structure or metabolism.
Fat mass above 25 % was associated with increasing insulin resistance, which independently predicted lifespan and chronic diseases.
diet-restricted dogs required 17 % less energy to maintain each lean kilogram.
Independent of feeding group, increased hazard of earlier death was associated with lower lymphoproliferative responses to phytohaemagglutinin, concanavalin A, and pokeweed mitogen; lower total lymphocytes, T-cells, CD4 and CD8 cells; lower CD8 percentages and higher B-cell percentages.
Modulation of canine immunosenescence by life-long caloric restriction. (2006) PMID 16567002 (sub-analysis)
Longitudinal effects of CR on the canine immune system are presented in this report.
A group of 48 Labrador Retrievers, divided at weaning into weight- and sex-matched pairs, were maintained on a diet restriction protocol from age 8 weeks until death.
Each restricted dog received 75% of the total food consumed by its control-fed pair mate.
Immune parameters were monitored from 4 to 13 years.
CR retarded age-related declines in both lymphoproliferative responses and absolute numbers of lymphocytes and the T, CD4, and CD8-cell subsets.
No direct effect of CR on phagocytic activity of PMN, antibody production or NK cell activity, was observed.
Lower lymphoproliferative responses, lower numbers of lymphocytes, T, CD4 and CD8 cells, lower CD8 percentages and higher B-cell percentages were all found to be significantly associated with a decreased likelihood of survival in these dogs.
A longitudinal study of the influence of lifetime food restriction on development of osteoarthritis in the canine elbow. (2009) PMID 19236677 (sub-analysis)
To report the effects of age and lifetime calorie restriction on development and progression of osteoarthritis (OA) in elbow joints of Labrador retrievers.
Labrador retriever dogs (n=48).
Puppies from 7 litters were allotted to 2 groups of 24 dogs each. Diet-restricted (DR) dogs received 25% fewer calories than control-fed (CF) pair mates.
Elbow radiographs were taken at 6 and 8 years of age and end of life (EOL).
Radiographic OA severity was greater for CF dogs at 6 years only (P<.05).
No differences in prevalence or severity of radiographic and histopathologic elbow OA were found between feeding groups. Diet restriction resulted in a 1.8-year extension in median lifespan but no additional incremental worsening of elbow disease.
Reproduce: canine_trial_search(trial_id="purina-lifetime-diet-restriction") in dog-geroscience-mcp; dataset canine-trial-registry.