Diet, Exercise, and Weight as Risk Factors in Hip Dysplasia and Elbow Arthrosis in Labrador Retrievers

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The WALTHAM International Nutritional Sciences Symposia
Diet, Exercise, and Weight as Risk Factors in Hip Dysplasia and Elbow
Arthrosis in Labrador Retrievers
1,2
Marie H. Sallander,
3
A
˚ke Hedhammar, and Mari E. H. Trogen
Department of Small Animal Clinical Sciences, Swedish University of Agricultural Sciences,
Uppsala, Sweden
EXPANDED ABSTRACT
KEY WORDS: hip dysplasia elbow arthrosis diet exercise weight dog
Hip dysplasia (HD) and elbow arthrosis (EA) are, despite
extensive breeding programs, still causing problems in many
dog breeds such as the Labrador Retriever. Among the
environmental factors involved in developmental bone dis-
eases, experimental studies show that overfeeding has proven
to be detrimental in both hip (1–3) and elbow dysplasia (3).
Over-supplementation of calcium has been shown to be a risk
factor for osteochondrosis, one of the main constituents of EA,
in both experimental (1) and epidemiological studies (4). In an
epidemiological study published in 1992, Slater et al. (4) found
that playing with other dogs might also be a risk factor for
osteochondrosis dissecans in dogs.
To register data on demographics, diet, exercise, and weight
in the Swedish dog population, a mail and telephone ques-
tionnaire was developed and validated (5). This tool was used
in this study to evaluate the effects of risk factors for HD and
EA in a defined population of Labradors.
Our research group is primarily investigating multifactorial
diseases in dogs that are of comparative value to humans. The
methods used for comparison are epidemiological and molec-
ular genetic studies, making use of insurance data and
population-based cases and controls matched by breed, sex,
and age (6).
To identify environmental risk factors concerning demo-
graphics, diet, exercise, and weight for both HD and EA, 2
parallel epidemiological studies were performed.
MATERIAL AND METHODS
Dogs
From the registries at the Swedish Kennel Club and out of a birth
cohort (born in 2000) of Swedish Labradors with known status on both
HD and EA at the age of 12–24 mo, 325 dogs were allocated as cases or
controls. A majority of the dogs were born from both sires and dams
unaffected by either HD or EA (82 and 81%, respectively) (6). The
dogs were matched by sex and age. Each case of HD was matched with
a control dog of the same sex, born at maximum 15 d apart from that
individual. If possible, the dog was also matched with a littermate (39%
of the cases). If more than 1 littermate was possible, the selection was
made by lot. The same procedure was followed with the EA cases.
The distribution of males (48%) and females (52%) were even. Only
2% of the dogs were neutered. Most (83%) had been purchased at the
age of 2 mo from a breeder. Dogs from 113 breeders were included in the
study, and 9% of the dog owners were breeders themselves.
Design and questionnaire
We performed 2 parallel retrospective case-control studies. The
owners of the cases and controls were sent a previously validated
questionnaire with a total of 39 questions regarding the specific dog
(5). After ;2 wk, the owner was contacted by phone and interviewed
by one of the authors (Mari Trogen).
The dietary section of the questionnaire included questions about
feeding patterns and appetite. Type, frequency, and amount consumed
of commercial food, table food, and homemade diets were recorded.
Owners were also questioned about treats and the use of vitamin and
mineral supplements. Another section of the questionnaire, concern-
ing exercise and the way the dogs perform and lead their lives,
recorded time spent on, and seasonal variations of, different training
activities. The final section identified the weight and size of the dog
compared with the average for the breed, as well as owner-perceived
body condition score.
Most questions were multiple choice or formulated to record continuous
data. In addition, some questions were open, to allow the possibility of
adding specific information. All questions, except the ones concerning
previous diets, pertained to dietary intake during the last month.
Calculation of nutrient intake
To calculate the daily energy and nutrient intake from commercial
feeds and other ingredients, the Animal Nutritionist (version 2.5,
1
Published in a supplement to The Journal of Nutrition. Presented as part of
The WALTHAM International Nutritional Sciences Symposium: Innovations in
Companion Animal Nutrition held in Washington, DC, September 15–18, 2005.
This conference was supported by The WALTHAM Centre for Pet Nutrition and
organized in collaboration with the University of California, Davis, and Cornell
University. This publication was supported by The WALTHAM Centre for Pet
Nutrition. Guest editors for this symposium were D’Ann Finley, Francis A. Kallfelz,
James G. Morris, and Quinton R. Rogers. Guest editor disclosure: expenses for
the editors to travel to the symposium and honoraria were paid by The WALTHAM
Centre for Pet Nutrition.
2
Author disclosure: no relationships to disclose.
3
To whom correspondence should be addressed. E-mail: marie.sallander@
kirmed.slu.se.
0022-3166/06 $8.00 Ó2006 American Society for Nutrition. J. Nutr. 136: 2050S–2052S, 2006.
2050S
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N-squared) software was used (7). The database was updated and
modified to suit Swedish conditions and included data on both table
foods (8) and commercial products used.
Statistical analyses
A McNemar Chi-square analysis was used to determine differences
in categorical variables between cases and controls (9). If there were
significant differences, the odds ratio (OR) was calculated. For
continuous variables, Student’s ttest and Wilcoxon Signed Rank test
were used (10). A value of P,0.05 was considered significant.
RESULTS
The overall response was 90% (292/325) and was equal for
cases and controls. Reasons for no response were that the owner
was unreachable during the time of the study (n¼14), the dog
was dead (n¼1), a lack of time or unwillingness to participate
(n¼12), the dog was sold (n¼5), or that the owner recently
bought the dog and did not know the dog’s background (n¼1).
For HD, 160 dogs could be matched (80 males and 80
bitches), and 32% of these were matched within litter. For EA,
124 dogs could be matched (58 males and 66 bitches), and 47%
of these could be matched within the same litter. Eight dogs
could not be matched with any dog but remained in the
material.
Most (median 93%) use of dry matter (DM) originated from
commercial dry feeds (78–100, 10th and 90th percentiles,
respectively). The median energy intake was 542 kJ/kg BW
0.66
(362–750).
Most dogs (98%) were taken for walks an average of 4 times/
d (min-max 0.4–7), with an average time of 100 min/d (10–
360). Fewer Labradors (19%) ran along side a bike, but the
Labradors performed this type of exercise an average of twice/
wk (0.25–7). Also, quite a few owners said that they were jog-
ging with their dog (15%) an average of twice/wk (0.25–7).
Most (85%) Labradors were allowed to play with other dogs,
most commonly 5 times/wk (median; min-max 0.3–100), most
commonly for 15 min on each occasion (2–60). Approximately
4 of 10 dogs were exercised by running after balls and sticks an
average of 4 times/wk (0.25–40) for 10 min on each occasion
(1–60).
The median weight of the males was 34 kg (min-max 22–
43), whereas the median weight of bitches was less (27 kg, min-
max 18–43 kg). When asked, only 4% of owners considered
their Labrador to be overweight. However, in a study previously
validated by Laflamme (11), when the owner pointed out their
dog’s size on a picture scale, 24% of the owners thought their
dog to be a 7 on a 1–9 grade scale. This means that the dogs are
overweight according to the body condition score system.
Three percent of the dogs were being fed to lose weight at the
time of the interview.
Risk factors for HD and EA
The results showed no significant difference between cases
and controls for either HD or EA in the proportion fed
homemade diets, table foods, commercial diets, or treats.
All individuals fed ad libitum were found in the case groups
for both HD (n¼4) and EA (n¼6). Identified risk factors for
both HD and EA were being exercised by running after balls
and sticks thrown by the owner (P,0.016, OR ¼2.4, 95% CI
2.2–2.6 for HD; P,0.014, OR ¼3.2, CI 3.0–3.5 for EA). For
HD, 54 and 35% of cases and controls performed the activity,
and, for EA, 52 and 34% of cases and controls performed the
activity, respectively.
A high body weight (medians 32 and 30 kg for cases and
controls, respectively; SD 4.4 and 3.7, respectively; P,0.05),
as well as a high intake of fat (medians 3.3 and 2.6 g/MJ,
respectively; SD 1.3 and 1.2, respectively; P,0.05) and
proportion of energy from fat (medians 34 and 30% of the
energy for cases and controls, respectively; SD 7.3 and 6.8,
respectively; P,0.02) was shown to be significant risk factors
for elbow arthrosis. A high body condition score was a pa-
rameter that was indicative/nearly significant as risk factor for
elbow arthrosis (3.29 and 3.11 on a 5-grade body composition
scale for cases and controls, and a SD of 0.90 and 0.93,
respectively; P,0.08).
DISCUSSION
This study has indicated feeding patterns and some types of
exercise as well as weight as significant risk factors in HD and/or
EA. As these factors may vary when studying multifactorial
diseases in populations, it has been shown that matching breed,
sex, and age among individuals is of value when performing
similar studies in the future (12).
This survey was based on a sample of the Swedish Labrador
population from the registry of the Swedish Kennel Club that
registers 85% of the pure-bred dogs in Sweden. Our sample
consists of a larger proportion of cases of HD and EA than the
entire source population that has ;23% HD and 10% EA (6).
Therefore, this sample may not be totally representative for the
entire population of Swedish Labradors. However, compared
with other studies in which cases and controls are taken from
veterinary clinics (4,12), we possibly have a better chance to
get a representative subsample of the population.
Although this study included few individuals with ad libitum
feeding, it should be noted that all of those were in the case
groups for HD and EA. This supports earlier studies (1–3) that
ad libitum feeding is a risk factor in developmental bone
diseases such as hip dysplasia and elbow arthrosis.
Many Labradors are living quite an active life even though
the main purpose of ownership might be companionship. Other
studies have indicated that prolonged or jarring activity, such as
running after a ball or a stick in a high speed, might lead to the
development of osteochondrosis (4). This study supports that
study and has shown that there might be an increased risk to
perform this type of activity for both HD and EA.
The conclusion is that in Swedish Labradors bred for hip and
elbow conformity, feeding patterns, diet, weight, and exercise
are risk factors that have to be taken into account in developing
preventive measures as well as in the design of research to
elucidate the multifactorial background of skeletal diseases.
LITERATURE CITED
1. Hedhammar A
˚,No
¨dtvedt A, Sallander M, Andersson G, Salmon
Hillbertz N, Bjo
¨rnerfeldt S, Malm S, Ferm K, Egenvall A. Swedish insurance
data and canine registries used to target populations and individual dogs
for studies on functional and comparative genomics. Poster nr 17, 2nd
International conference: Advances in Canine and Feline Genomics. Utrecht
University, The Netherlands. Oct. 14–16, 2004.
2. Kasstro
¨m H. Nutrition, weight gain and development of hip dysplasia. An
experimental investigation in growing dogs with special reference to the effect of
feeding intensity. Acta Radiol Suppl. 1975; 344: 135–79.
3. Kealy RD, Lawler DF, Ballam JM, Lust G, Biery DN, Smith GK, Mantz SL.
Evaluation of the effect of limited food consumption on radiographic evidence of
osteoarthritis in dogs. J Am Vet Med Assoc. 2000;217:1678–80.
4. Slater MR, Scarlett JM, Donoghue S, Kaderly RE, Bonnett BN, Cockshutt
J, Erb HN. Diet and exercise as potential risk factors for osteochondritis dissecans
in dogs. Am J Vet Res. 1992;53:2119–24.
5. Sallander MH, Hedhammar A
˚, Rundgren M, Lindberg JE. Repeatability
and validity of a combined mail and telephone questionnaire on demographics,
2051SRISK FACTORS IN HIP DYSPLASIA AND ELBOW ARTHROSIS
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diet, exercise and health status in an insured-dog population. Prev Vet Med.
2001;50:35–51.
6. SKC (Swedish Kennel Club). Statistics of scanning of Labradors for HOD
and EA. Stockholm, Sweden 2000. Available from: http://www.skk.se, last ac-
cessed 12 Sept 2002.
7. Animal Nutritionist. Version 2.5. N-squared Inc [CD-rom]. Silverton, OR:
Durango Software; 1987.
8. National Food Administration. [Food composition table – energy and
nutrients.] [In Swedish.] Uppsala, Sweden: National Food Administration; 1996.
9. Kleinbaum D, Kupper L, Morgenstern H. Epidemiologic research
principles and quantitative methods. 1982.
10. Wayne D. Biostatistics: a foundation for analysis in the health sciences.
6th edition. New York: John Wiley & Sons; 1995.
11. Laflamme DP. Development and validation of a body condition score
system for dogs. Canine Pract. 1997;22:10–5.
12. Slater MR, Scarlett JM, Kaderley RE, Bonnett BN. Breed, gender and age
risk factors for canine osteochondritis dissecans. Vet Comp Orthop Traum.
1991;4:100–6.
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