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Daniel P. Carey, DVM
Allan J. Lepine, PhD
Research and Development Division
The Iams Company, Lewisburg, Ohio, USA
INTRODUCTION
The art of dog breeding has never been easy. Long-term
success has eluded many breeders. In the past, accomplishment
was easier because we only bred for a few traits (eg,
size, working ability, or general appearance). We
were merely trying to conform to a standard. Today’s
breeder has a much larger challenge because multiple
conformation traits, temperament, agility, utility,
and health problems all must be considered when planning
a mating. As the number of parameters increase, the
difficulties with the project escalate. It is no wonder
that many become discouraged and frustrated over time.
Successfully breeding dogs is not an easy mission.
 Breeders
and exhibitors of the large and giant breeds are faced
with even more difficulty because of a number of developmental
conditions involving the bones and joints. Diseases
like hip dysplasia, hypertrophic osteodystrophy, panosteitis,
and osteochondrosis are frequently-discussed topics
at health seminars, national specialties, or anywhere
fanciers of the large and giant breeds gather. These
skeletal conditions seem to be diagnosed at an even
more common rate than in the past. Occurring during
the rapid growth stages of pups and adolescent dogs,
some of these diseases can devastate a kennel.
Obviously, different breeds of dogs grow at different
rates (Figure 1). Some large breed dogs are the same
size and weight at birth as 3 month old Chihuahuas!
And by 8 months of age, those dogs increase in size
and weight to 80 or 100 pounds while many of the toy
breeds are less than a few pounds at the same 8 months!
It is only logical that large or giant breeds
of dogs undergo tremendous meta-bolic and struc-tural
changes to allow for the “hyper-space” type
growth. Sometimes breeders are drawn to those puppies
in the litters that have bigger bone struc-ture. These
particular puppies seem appealing because of the “extreme”
characteristics that are desired in a particular breed.
But, often those very puppies are the ones that may
become plagued with panosteitis or osteochondrosis.
So, is bigger really better? What are some of the
influences on whether our puppy is the one to develop
a certain developmental bone disease. Where does diet
fit in? What can we do as breeders to avoid getting
it or perpetuating it in our lines? These are a few
of the questions we will attempt to answer.
Let’s examine the various types of commonly seen
developmental bone diseases and how they present themselves
in our growing or adolescent dogs.
DEVELOPMENTAL
BONE DISEASES
Osteochondrosis
Osteochondrosis is a common cause of lameness in growing
large and giant breeds with a high incidence in the
Great Dane, Labrador Retriever, Newfoundland, and
Rottweiler.  Osteochondrosis
is the degeneration or breakdown of bone and cartilage
of certain joints. It commonly is followed by regeneration
or calcification of the tissues of the joint while
it attempts to heal. It typically occurs in growing
dogs between 5 and 9 months of age and is often associated
with rapid growth. Dogs with osteochondrosis usually
present to their veterinarian with pain, lameness,
and swelling of the shoulder, elbow, hock, or stifle
joints. It is considered a systemic disease and affects
more than one or 2 joints at a time although it may
show in only one. When the breakdown of the cartilage
occurs in some of these joints, occasionally small
sections of tissue can break loose inside the joint
forming a calcified “joint mouse.” This
is more commonly known to breeders then as osteochondrosis
dessicans or as “OCD.”
Hypertrophic Osteodystrophy
Hypertrophic osteodystrophy is another common cause
of lameness of puppies in breeds such as Great Danes,
Saint Bernards, Boxers, Dalmatians, Irish Setters,
German Shepherds, Labrador Retrievers, Collies, and
other rapidly growing large breeds at 3 to 8 months
of age. It is a condition characterized by abnormal
bone growth of the lower front leg (of the radius
or ulna – the area just above the carpus). This
results in large “wrists” and, sometimes,
bowed legs. These puppies may also have an elevated
body temperature and/or become anorexic or not interested
in eating their food.
Hip Dysplasia
 Of
all the skeletal diseases of dogs, hip dysplasia is
the most well known. It is a developmental disease
of the hip joint where luxation of the femur from
the socket (acetabulum) of the pelvis causes remodeling
of this joint. The acetabulum becomes shallow with
flattening of the head of the femur. The mismatch
of the ball and socket leads to arthritis. Early cases
of hip dysplasia may have signs of mild discomfort
after exercise or a general mild lameness. As the
condition progresses, lameness, pain, abnormal gait,
reluctance to rise and a thinning of muscling of the
thighs may occur. Hip dysplasia is a polygenic disease
(involves many genes) that can be influenced by diet.
Rapid growth or rapid weight gain can aggravate the
lameness of hip dysplasia.
Panosteitis
Panosteitis is another commonly discussed bone disease
in the breeder arena. This condition is also known
as eosinophilic panosteitis, “Pano” or “Eo
Pan”, which is the most common terminology used
by breeders. It is a disease of the long bones of
the forelimb such as the humerus, radius or of the
hind leg including the femur or tibia of large and
giant breeds of dogs. German Shepherds seem to have
a higher incidence of this condition. However, any
breed can be plagued by this condition especially
puppies with extremely large bone. Although this condition
can cause extreme lameness and be alarming to the
average breed or owner, it is self-limiting, and there
is no permanent damage or aftermath of the condition.
It is most often seen during growth spurts with affected
pups usually losing their appetite in addition to
showing lameness.
Most commonly puppies will have acute onset of lameness
with no history of trauma. Male puppies are 4 times
more affected than females.1 Puppies with panosteitis
will often “carry” or favor the limb that
is affected for just a few days or many weeks. Often,
the puppy will appear to have a “shifting leg
lameness,” that is, they appear to be lame on
one leg one day and another leg the next. Such puppies
usually have panosteitis of multiple bones and limp
on the one that hurts the most.
What influences the developmental bone diseases? Where
does diet fit in? What can be done to avoid these
problems in puppies?
It is known that all skeletal development is affected
by four major areas:
GENETICS
As we all know, “the genes
make the dog.” Therefore genetics can play a significant
role in the development of certain bone diseases. Puppies
from very large boned parents may have large bones and
be more apt to develop panosteitis. Puppies from dysplastic
parents are much more likely of becoming dysplastic. Puppies
from parents who were rapidly growing are more likely
to grow rapidly, too.
When considering genetics and nutrition together, there
are 2 well-known nutritional truths. The first is that
growth rate and adult size are programmed in the genes
for every puppy. The second is that increasing the energy
intake (supplying more calories) to a puppy can push the
growth rate to its upper limit and thus increase the likelihood
of certain skeletal diseases. This leads to the next topic
of discussion– nutrition.
NUTRITION
Nutrition can influence the development of certain developmental
bone diseases in 3 areas: protein content of a diet, energy
content or calories fed, and calcium intake (whether as
part of the diet or as a supplement).
Dietary Protein
In the past, some diets were said to be “too hot”
(ie, contained high levels of dietary protein) and promoted
rapid growth rate predisposing large and giant breed dogs
to skeletal problems. However, controlled research done
in 1991 by Nap et al.,2 showed that protein
was uninvolved. Great Dane puppies were fed identical
diets except for the protein content from weaning for
18 weeks. These diets had a broad range of dietary protein
compositions of 31.6%, 23.1% and 14.6%. This research
demonstrated that skeletal development problems were NOT
related to variations of the dietary protein content.
Thus, protein in and of itself does not effect bone development
or influence the incidence of developmental bone diseases.2,3
(The low-protein diet did have some problems keeping weight
on the pups.)
Energy
Density
However, research done by Hedhammer did find a nutritional
factor that does influence the incidence of certain developmental
bone diseases. This researcher investigated the issue
of dietary energy intake (how many calories a puppy ate
each day) by feeding either (1) as much as the puppy wanted
to eat [ad libitum] or (2) a restricted amount of food
[66% of the ad libitum amount]. This research was also
done on Great Dane puppies which were fed until the puppies
were 60 weeks of age (approximately 15 months old). He
found that the puppies fed as much as they wanted (ad
libitum) had a significantly higher incidence of skeletal
abnormalities than those puppies who were fed a restricted
amount of food (meal fed).4
Another researcher (Dammrich) in 1991 confirmed this fact
by doing research on Great Dane puppies fed ad libitum
or a restricted diet of 70-80% of the ad libitum fed puppies.5
His research was done from weaning until 6 months of age.
He proved that puppies fed as much as they wanted had
weaker bone and inadequate support of the joint cartilage.
Thus, those puppies fed as much as they wanted had a significantly
higher frequency of developmental bone diseases.5
Iams research has also shown that the number of dogs showing
the radiographic changes of osteochondrosis and HOD increases
as the number of calories consumed increases. In other
words, pups that get too many calories grow fast and are
more likely to have developmental bone problems.
Calcium
The amount of calcium in a
diet has also been demonstrated to have significant effects
on the development of the skeleton of the large or giant
breed puppy. Research done by Hazewinkel et al. showed
that diets too high in calcium have been shown to have
detrimental effects on puppies’ endocrine systems,
blood levels of calcium and skeletal development and will
increase the risk of developmental bone diseases. Specifically,
high levels of calcium affected bone development by causing
retained cartilage cones, increased bone mineral, and
delayed bone remodeling. These puppies had more abnormalities
seen on their radiographs (x-rays) with more osteochondritic
lesions (osteochondrosis).6,7
Another research project done by The Iams Company evaluated
3 diets containing 26% protein and 14% fat, but differing
in the calcium and phosphorus levels: 
Great Danes puppies were fed the
various diets from pre-weaning until 18 months of age.
During this research growth rate, body composition, bone
mineral density or composition, and skeletal integrity
were evaluated. This research demonstrated that diets
with 0.8% calcium and 0.67% phosphorus level provided
ideal mineral levels for healthy bone growth and development
for large breed dogs. Puppies fed the diet with these
levels had better conformational or skeletal structure.
These puppies also had a lower prevalence of developmental
bone disease or clinical signs of lameness.8-11
Environment
Environment
also can influence the incidence of certain types of developmental
bone diseases occuring in our large breed dogs. Environmental
influences are anything that can effect an animal from
non-genetic sources. Space for exercise and exercise (or
lack of) and conditioning are considered environmental
influences. Dogs that are not exercised properly do not
develop adequate muscling or tendon strength, and thus
these things can alter bone density and development. Slippery
floors or awkward footing can lead to abnormal gait and
altered bone development, particularly in very young puppies.
Trauma
Any type of trauma, especially to the rapidly growing
large or giant breed dog can effect both bone and joint
development. Broken bones, slipped growth plates, or injured
joint cartilage can all be factors that determine whether
dogs can be predisposed to developing bone or joint problems
in the future. Thus it is important to allow for proper
exercise and conditioning of large breed dogs, but not
to stress their delicate, young skeletons which may cause
injury that could be permanent. Puppies should not be
pushed to perform. A puppy with an otherwise unnoticeable
osteochondrosis often has a history of running and pulling
up lame. The combination of a developmental bone disease
and trauma created the lameness. Surfaces and conditions
should be carefully evaluated to avoid dangerous structures
for dogs. Trauma-related injury can be avoided by using
common sense and light exercise.
Practical
Implications
Large
and giant breed dogs can be plagued by the occurrence
of certain bone diseases during their early and adolescent
growth stages. Genetics, environment, and nutrition can
influence the development of these conditions.
Based on recent research, nutrition can play a key role
in decreasing the occurrence and severity of these diseases.
Some of the concepts we know now exist are:
 Managed
growth rate is important in reducing the incidence of
skeletal disease
- Rapid rate of growth contributes to the incidence
of skeletal abnormalities. Feed a diet with around
15% fat to provide enough calories for growth
but not so much as to fuel rapid growth.
- Dietary protein has little impact on skeletal
disease. Feed a diet with about 26% protein to
support muscle development.
- Mature size is genetically programmed.
Support healthy bone development
- Appropriate dietary calcium and phosphorus concentrations
are essential. The diet should have a calcium
level of 0.8 to 0.9% and be balanced with phosphorus.
- Calcium supplementation or high calcium diets
can increase the incidences of certain developmental
bone diseases. Any supplementation whether as
calcium, bone meal or dairy products will increase
the calcium intake and increase the puppy's likelihood
of developmental bone disease.
Breeders CAN influence the frequency
of certain bone diseases occurring in their kennel by
implementing proper feeding management of their puppies,
considering the genetic potential of the heritage of their
dogs, exercising and conditioning properly, as well as
preventing trauma or damage to growing bones and cartilage
of their puppies.
REFERENCES
- Barrett RB, Schall WD, Lewis RE: Clinical and
radiographic features of canine eosinophilic panosteitis.
J Am Anim Hosp Assoc 1968; 4:94-104.
- Nap RC, Hazewinkel HAW, Voorhout G, Van De Brom
WE, Goedegebuure SA, Van'T Klooser ATh. Growth
and skeletal development in Great Dane pups fed
different levels of protein intake. J Nutr 1991;
121:S107-S113.
- Nap RC, Hazelwinkel HAW, Voorhout G, Biewenga
WJ, Koeman JP, Goedegebuure SA, Van't Klooser
ATh. The influence of dietary protein content
on growth in giant breed dogs. J Vet Comp Orth
Traumatolo 1993; 1-8.
- Hedhammer A, Wu F, Krook L, Schryver HF, Delahunta
A, Whalen JP, Kallfelz FA, Numez EA, Hintz HF,
Sheffy, Ryan GD. Overnutrition and skeletal disease.
An experimental study in Great Dane dogs. Cornell
Vet 1974; 64 (suppl. 1): 1-160.
- Dammrich K. Relationship between nutrition and
bone growth in large and giant dogs. J Nutr 1991;
121(11 Suppl):S114-21
- Hazelwinkel HAW, Goedegebuure SA, Poulos PW, Wolvekamp
WThC. Influences of chronic calcium excess on
the skeletal development of growing Great Danes.
JAAHA 1985; 21:377-391
- Goedegebuure SA, Hazewinkel HAW. Morphological
findings in young dogs chronically fed a diet
containing excess calcium. Vet Pathol 1986; 23:594-605.
- Lauten SD, Brawner Jr WR, Goodman SA, Lepine AJ,
Reinhart GA, Baker HJ. Dual energy x-ray absorptiometry
measurement of body composition and skeletal development
in giant breed dogs fed diets differing in calcium
and phosphorus. FASEB J 1997; A388.
- Lauten SD, Brawner Jr WR, Goodman SA, Lepine AJ,
Reinhart GA, Vaughn DM, Baker HJ. Body composition
of growing Great Dane puppies fed diets varying
in calcium and phosphorus concentrations evaluated
by dual energy x-ray absorptiometry. ACVR 1996;
1-8.
- Brawner Jr WR, Hathcock JT, Goodman SA, Lauten
SD, Cox NR, Kincaid SA, Baker HJ, Lepine AJ. Radiographic
lesions observed in growing Great Dane puppies
fed diets varying in mineral content: a preliminary
report. ACVR 1996; 1-9.
- Goodman SA, Montgomery RD, Lauten SD, Hathcock
JT, Brawner Jr WR, Cox NR, Kincaid SA, Reinhart
GA, Lepine AJ, Baker HJ. Orthopedic observations
in Great Dane puppies fed diets varying in calcium
and phosphorus content: a preliminary report.
Veterinary Orthopedic Society 24th Annual Conference
Proceedings; 1997; 51.
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