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Supplement: WALTHAM International Science Symposium: Nature, Nurture, and the Case for Nutrition

Body-Weight Changes during Growth in Puppies of Different Breeds¹

WALTHAM Centre for Pet Nutrition, Waltham-on-the-Wolds, Leicestershire, UK and ^* Department of Statistics and Modelling Science, University of Strathclyde, Glasgow, UK

² To whom correspondence should be addressed. E-mail: amanda.hawthorne{at}eu.effem.com.

KEY WORDS: • dog • growth curve • puppy

Introduction

As a species, the dog is unique. Depending on the breed, body weight varies 100-fold from the 1-kg Chihuahua to the 115-kg St. Bernard (1). The time taken for a growing puppy to achieve adult body weight also varies considerably with larger breeds having a longer growth period than smaller breeds. Also the rate of growth during this period is not constant; energy requirements decrease from 3 times maintenance at weaning to1.2 times maintenance as the puppy approaches adulthood (1).

The provision of accurate feeding guides is essential if under- and overnutrition are to be prevented. Overnutrition of dogs results in obesity, but in large breeds overnutrition also causes musculoskeletal disorders (2,3). However, present feeding guides are based on "typical" growth data that use only a single equation (4,5).

Breed-specific differences in growth patterns might be expected due to huge variations in size, temperament, and coat type, all of which are likely to affect energy requirements. This was evident in a study of six breeds of puppies that demonstrated very different energy requirements despite similar absolute body weights in Great Danes versus Newfoundlands and Briards versus Labrador Retrievers (6). Little information is published on breed-specific variations in puppy growth patterns, and most studies provide only limited data on single breeds, for example, 8–34-mo-old and 6–20-wk-old Labrador Retrievers (7,9) and 0–12-wk-old German Shepherds (8). Other studies are confounded by the use of different groups of dogs to provide data for a variety of age groups (10). Comparisons between these studies are difficult due to differing data presentation and treatment.

The aim of this study was to compare the complete growth curves of 12 different-sized dog breeds and to investigate a mathematical basis for the provision of breed-specific feeding guides.

	METHODS AND MATERIALS

TOP METHODS AND MATERIALS RESULTS LITERATURE CITED

 
Puppies (n = 173; 90 male, 83 female) representing 12 dog breeds ranging in size from toy to giant were included in the study (Table 1). The puppies were recruited into the study either at birth (Newfoundlands, Labrador Retrievers, English Springer Spaniels, Cocker Spaniels, Miniature Schnauzers, and Cairn Terriers) or at 8–11 wk of age (other breeds) and were studied until they were 12 mo old (toy to medium-sized breeds) or 18 mo old (large and giant breeds). Throughout this period, the puppies were fed a variety of commercially available, nutritionally complete diets that are formulated for puppy growth, at a level designed to maintain optimum body composition. All puppies were weighed once weekly using calibrated electronic scales, although after 50 wk of age, the Newfoundlands were weighed only every other week.

Statistical analysis

For each breed, a growth curve was constructed by plotting mean body weight against age. The logistic equation,

was fitted to each growth curve using SPSS SigmaPlot software (SPSS Science Software, Erkrath, Germany). This provided estimates of the adult maximum body weight achieved (a), the growth rate (1/b) during the early exponential phase, and the time taken to reach 50% maximum body weight (x₀).

Cluster analysis (XLSTAT, Addinsoft, Paris, France) was used to group the breeds (via Ward's inertia method) on the basis of a combination of exponential growth rate, adult body weight, and time taken to reach 50% of maximum weight.

	RESULTS

TOP METHODS AND MATERIALS RESULTS LITERATURE CITED

 
The growth curve for each breed is presented in Figure 1. The fit of the equation to each curve was excellent, with R² > 0.979 in all cases (Table 1), which indicates that the fitted curves accounted for almost all of the observed variation.

View larger version (26K): [in this window] [in a new window]   FIGURE 1  Mean growth curves for 12 breeds of dogs (SEM bars are excluded for clarity): English Mastiff (), St. Bernard (•), Irish Wolfhound (----), Great Dane (), Newfoundland (+), Labrador Retriever (—), Beagle (), English Springer Spaniel (), Cocker Spaniel (), Miniature Schnauzer (•••), Cairn Terrier (x), and Papillon (----).

The growth rates during the exponential phase (approximating to the rate of increase of body weight per week) were, however, relatively similar. The slowest exponential growth rate was recorded for English Mastiffs (10.8%) and the fastest was achieved for English Springer Spaniels (18.3%), although most breeds fell within the range of 13–17% per wk (Table 1).

Adult body weight is achieved when the growth rate falls to zero. However, this cannot be calculated using logistics curves, which run to infinity. Therefore, the age at which each breed reached 99% of adult weight (T₉₉) was calculated. Toy, small, and medium breeds reached 99% of their adult weight at 9–10 mo, whereas large and giant breeds reached this point at 11–15 mo (Table 1).

The dendrogram obtained from cluster analysis (Fig. 2) shows that the growth characteristics as reflected by the logistics model parameters identify distinct clusters. In Figure 2, horizontal distances indicate dissimilarity between clusters as measured by the Euclidean linkage distance between breeds. Two distinctly dissimilar clusters are seen; one consists of giant breeds and the other of large, medium, small, and toy breeds. These clusters subdivide further into two more clusters. Although breeds in these four clusters were less dissimilar, the Papillons, Labrador Retrievers, and Newfoundlands were the most different within their respective clusters.

View larger version (13K): [in this window] [in a new window]   FIGURE 2  Cluster-analysis dendrogram of the growth characteristics (exponential growth rate, adult body weight, and time taken to reach 50% maximum weight) of 12 breeds of dogs.

Conclusions

Feeding guides have long taken into account the extended growth period of larger dog breeds, but to date this has been based mostly on assumed growth curves (4,5). The finding that based on the logistics model parameters used here, these differences can be demonstrated mathematically, supports present feeding guides and practices. Thus although a toy or small-breed dog may be considered an adult (and fed accordingly) from 9 mo of age, adulthood in the largest breeds is not achieved until 15 mo of age.

However, the data also suggest that additional differences in growth patterns may exist in breeds of similar size. For example, cluster analysis separated the Newfoundlands from the other giant breeds and distinguished Labrador Retrievers from English Springer Spaniels and Beagles in the medium- and large-sized categories. Because cluster analysis uses a combination of parameters to determine dissimilarity between groups, it is not possible to determine from the present data why these similar-sized breeds were separated. However, the Newfoundlands had a lower adult weight (a) and higher exponential growth rate (1/b) compared with the other giant breeds. In addition, sex-ratio differences for the different breed groups studied (Table 1) complicate interpretation, because males and females may have different growth patterns. Sex differences were reported in previous studies (10,11) with males taking longer to reach adulthood than females. Whether this sex effect occurs in all breeds or has any practical impact remains to be seen, but it may explain some of the differences observed here including the separation of Cocker Spaniels from other small-sized breeds (sex-specific data not shown). These breed-specific differences in growth pattern warrant additional study.

The dogs in this study were housed at the WALTHAM Centre for Pet Nutrition in surroundings as similar to a domestic household as can be achieved in a kennel environment. Although subtle differences in activity level in kenneled dogs will undoubtedly affect energy requirements compared with the pet population, this is unlikely to affect the growth pattern. The dogs were fed a variety of different diets throughout the period of study; however, this situation closely reflects that of a domestic pet, which makes these data useful for practicing veterinarians.

In summary, this study supports the empirical feeding guides in use for breeds of different sizes, identifies breeds with similar growth profiles, and suggests that additional breed-specific differences in growth patterns may occur even in dogs of similar size.

	FOOTNOTES

 
¹ Presented as part of the WALTHAM International Science Symposium: Nature, Nurture, and the Case for Nutrition held in Bangkok, Thailand, October 28–31, 2003. This symposium and the publication of the symposium proceedings were sponsored by the WALTHAM Centre for Pet Nutrition, a division of Mars, Inc. Symposium proceedings were published as a supplement to The Journal of Nutrition. Guest editors for this supplement were D'Ann Finley, James G. Morris, and Quinton R. Rogers, University of California, Davis.

	LITERATURE CITED

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1. Burger, I. H. (1994) Energy needs of companion animals: matching food intakes to requirements throughout the life cycle. J. Nutr. 124: 2584S–2593S.

2. Meyer, H. & Zentek, J. (1992) The influence of various levels of energy intake on the body weight and skeletal development of growing Great Danes. 1. Body weight development and energy requirement [in German]. Zentralbl. Veterinarmed. A. 39: 130–141.[Medline]

3. Dammrich, K. (1991) Relationship between nutrition and bone growth in large and giant dogs. J. Nutr. 121: S114–S121.

4. Blanchard, G., Grandjean, D. & Paragon, B. M. (1998) Calculation of a dietary plan for puppies. J. Anim. Physiol. Anim. Nutr. 80: 54–59.

5. Meyer, H. & Zentek, J. (2001) Ernaehrung des Hunde (Nutrition of the dog), 4th ed. Blackwell Wissenschafts-Verlag, Berlin.

6. Rainbird, A. & Kienzle, E. (1990) Untersuchungen zum Energiebedarf des Hundes in Abhaengigkeit von Rassezugehoerigkeit und Alter (Investigations on the energy requirements of dogs in relation to breed and age). Kleintierpraxis 4: 145–158.

7. Alexander, J. E. & Wood, L. L. H. (1987) Growth studies in Labrador Retrievers fed a caloric-dense diet: time restricted versus free choice feeding. Canine Pract. 14: 41–47.

8. Schroeder, G. E. & Smith, G. A. (1994) Food intake and growth of German Shepherd puppies. J. Small Anim. Pract. 35: 587–591.

9. Booles, D., Poore, D. W., Legrand-Defretin, V. & Burger, I. H. (1994) Body composition of male and female Labrador Retriever puppies at 20 wk of age. J. Nutr. 124: 2624S–2625S.

10. Allard, R. L., Douglass, G. M. & Kerr, W. W. (1988) The effects of breed and sex on dog growth. Comp. Anim. Pract. 2: 15–19.

11. Helmink, S. K., Shanks, R. D. & Leighton, E. A. (2000) Breed and sex differences in growth curves for two breeds of dog guides. J. Anim. Sci. 78: 27–32.[Abstract/Free Full Text]

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