Concern is growing about the effects of high calcium diets on dogs. This study showed no adverse health effects of high calcium in dog diets as the animals were capable of excreting the excess.Presented at the Waltham International Nutrition Science Symposium, October 2016, Chicago.

1. Evaluation of a high calcium intake on health
and physiological parameters in adult dogs
J. Stockman, M. Gilham, D. Allaway, J. Atwal,
A. Colyer, R. Haydock, H. Renfrew,
B. Dobenecker, E. Kienzle, P. Morris, P. Watson
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2. iCa
PTH
1,25(OH2)D3
GI Ca2+
absorption
Osteoclast
activity
Renal Ca
resorption
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Brito Galvao et al. J Vet Emerg Crit Care 2013
Calcium Regulation

3. Background
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Mack et al. J Anim Physiol Anim Nutr (Berl). 2015
X=Y

4. Background
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• Lack of adaptation of fecal Ca excretion
in response to high intake may result in
either a positive Ca balance or an
increase in urinary Ca excretion
• Under conditions of long term Ca excess,
a bioaccumulation of Ca may occur that
would present issues to health
• However, most studies are of a relatively
short duration (<28 d)

5. Aims
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1. To evaluate the effect of feeding a diet containing
7.1 g/1000 kcal Ca for 40 weeks on a wide range of
health parameters in adult dogs
2. To determine whether dogs are able to regulate calcium
balance when fed in excess of Ca requirements

6. Study design
• 18 adult Labrador retrievers, habituated to all trial procedures
• All dogs maintained ideal Body Condition Score and body weight
within range (+/- 5%)
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Control Test
# Labradors 8 dogs 10 dogs
Age (y) 3.0 (2.5-4.4) 3.4 (2.5-7.4)
Body weight (kg) 26.5 (22.5-29.0) 27.4 (21.0-32.0)

7. Diets
Control Test
Calcium (g/1000 kcal) 1.7 7.1
Phosphorus (g/1000 kcal) 1.1 4.5
Ca:P 1.6 1.6
Vitamin D (IU/1000 kcal) 208 200
Sodium (g/1000 kcal) 1.2 1.1
Protein (g/1000 kcal) 72 80
Fat (g/1000 kcal) 32 35
Base Excess (Meq/Kg) 175 175
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• Two complete and balanced dry extruded diets were formulated and
manufactured using similar ingredients and ratios

8. Study Timeline
n=18
Control diet
n=10 Test Diet
n=8 Control Diet Ca 1.7 g/1000 kcal; Ca:P=1.6
Ca 7.1 g/1000 kcal; Ca:P=1.6
Wk
2 4 6 8 2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36 38 40
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9. Measures
• Health parameters: Complete blood count & biochemistry,
ventrodorsal and right lateral recumbent radiographs and
ultrasound scans
• Urinary/renal parameters: including iohexol clearance, creatinine,
urine relative super saturation
• Bone health parameters: Bone ALP, serum cross laps, DXA
• Related hormones: PTH, vitamin D metabolites
• Mineral balance and diet digestibility: calculated through 5 day
fecal and urine collection, along with dietary intake data
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10. Results: General health
• 17/18 dogs completed the study successfully; 1 dog from the test
group was removed due to unrelated reasons on week 24
• All other dogs remained in apparent good health throughout
• No evidence of soft tissue mineralization
• No evidence of skeletal pathology
• No urolithiasis

11. Results: Kidney function
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mean ± 95% CI
p < 0.05

12. Results: Bone turnover markers
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mean ± 95% CI

13. Results: Calcium regulation
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µ
mean ± 95% CI

14. Results: Calcium balance
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mean ± 95% CI

15. Proprietary information: Not to be reproduced or distributed without the express consent of Mars Inc. ©Mars 2016
Results: Digestibility coefficients
mean ± 95% CI
p < 0.05

16. Discussion
• No evidence of any health related changes as a result of a high
calcium intake
• Calcium balance was stable throughout the study, suggesting dogs
are capable of adapting fecal Ca excretion in response to intakes
above requirements
• Reduced dry matter digestibility was apparent with the high Ca diet
• Considerations:
– Single breed; a second study has recently completed to confirm
these findings
– Different Ca:P ratios or calcium sources were not evaluated
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17. Conclusions & Context
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• The present study demonstrates that Ca intakes of up to 7.1 g/1000
kcal are well tolerated over a period of 40 weeks, with no adverse
effects that could be attributed to the diet or to a high mineral intake
• These data provide evidence that adult dogs are able to tolerate
higher Ca intakes than puppies, and this will enable more precise
recommendations for Ca safe upper limit in adult dogs

18. Results: Body weight and caloric intake
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19. Results: DXA
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20. Results: Renal & urinary health parameters
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21. Results: Digestibility coefficients
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22. Results: ionized calcium
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