Litter Size and Singleton
By
Dr. Carmen L. Battaglia
| This article has
been reproduced with the kind permission of Dr. Carmen
L. Battaglia for the CFBA, the CIDBT, and their students
of Dog Behaviour & Training |
When two or more breeders gather together their
conversation often times center on the number of pups born and
what might have gone wrong. For years breeders have speculated
on why some litters are larger than others. Since most breeders are
not trained in biology or in veterinary medicine a review of
these questions was addressed.
Background:
Nature has always allowed animals to adapt to their living conditions.
For example, horses and cattle live in herds as herbivores and
cover considerable distances each day. They tend to have a long
period of gestation and produce a single offspring. Their young
are born among the herd as it moves slowly because only in the
middle of the great herd can they be protected. The problem is
quite different for canines. They live in small communities and
their young are born in a safe hideout. Because they hunt they
can not afford a long period of gestation. The reason that carnivores
usually do not have single offspring litters stems from the nature
of their existence. They must be constantly hunting to struggle
for existence and the casualties among their young are high.
Severzov calculated that the morality among young wolves was
45 % at the end of the first year and a further 32% by the end
of their second year with a total loss of about 77% for all young
wolves. If their litters consisted of only a few pups, the likelihood
would diminish that the survivors could contribute to maintaining
the survival of the species.
There are several ways to approach the study of litter size
in dogs. One perspective is to look at what can influence
the size of a litter; another is to study one-puppy litters. Goldbecker
and Hart reported experiences with both. For the one-puppy litters
they suggested the use of foster mothers and to treat the singleton
as an orphan because they have similar problems. They believed
that these pups needed siblings or other dogs to interact with
in order to learn the rules of the dog world. To that end it
is generally accepted that at least for canines, littermates
provide valuable and necessary practice sessions. Interactions
provide opportunities for using their teeth, developing eye contact
and a wide range of other canine behaviors that become useful
as adults.
Most of the small breeds, notably the toys and terriers usually
produce very small litters. This is in part because of their
very small size, which limits their capacity to carry large litters.
But in the larger breeds there are wide variations in litter
size ranging from 1 to 21 and in a some instances they have been
larger. Breeders have for years unsuccessfully tired to make
improvements in litter size via breeding and selection techniques
with little success. While many traits have high heritability,
litter size is not one of them. It has a low heritability, around
10 -15 % which means that one can not count on the genes to increase
the number of pups born. What can be expected will largely
be determined by the non-additive factors of dominance. For
example, wither height has a heritability estimate of 40-65%,
which is reasonably high. Therefore, it is relatively
easy for the breeders of the German Shepherd Dog to produce offspring
with high withers. However, when it comes to litter size selecting
parents who come from large litters will not improve the number
of pups born. However, the physical condition of the dam
at the time she is bred however has been shown to increase or
decrease litter size. For example, obese bitches tend to have
smaller litters than those that are fit and trim. Nutrition is
still another factor that was suspected to affect litter size.
Some thought it would vary between and within breeds. The fact
that there are large variations in litter size attracted the
attention of Russ Kelly, a noted nutritionist. He set out to
better understand litter size by examining what would happen
if nutrition became the variable. What he found was that the
diet fed bitches during their pregnancy did influence the size
of their litters. To do this he studied three colonies of bitches
that were in whelp. One colony was fed only a dry ration of good
quality dog food. The second was fed the same dry ration but
supplemented with cottage cheese. The third was fed the same
dry ration with supplements of cottage and meat. The important
point here is that two of the three colonies were fed extra protein
supplements. The colony that had the largest number of pups born
alive came from mothers not fed any supplements. His findings
make clear that supplementing a high quality, nearly perfectly
formulated dog food with rations of cottage cheese and meat would
interfere with the number of pups born alive. In other
words, supplements added to a good quality commercial dog food
reduces the chances for larger litters. This finding is good
news to dog breeders.
Singleton pups
The singleton pup is a one-puppy litter. To better understand
these pups three general questions were used. They focused
on the whelping process, behavior during and after weaning
and the effects of the dam during their development. While
many species have single births the canines are not one of
them even though there are many breeds that only produce one
or two puppy litters. Small litters can be directly related
to the selective breeding practices that breeders have used
over the years to fulfil the physical size requirements of
their breed standards. The other explanation for variations
in litter size has already been demonstrated to be nutrition
and conditioning.
Since there was no body of literature on this subject several
breeders and veterinarians were contacted that had reported experiences
with single puppy litters. Many of the breeders said that a singleton
pup could be a little dog aggressive, less sociable and a little
more "abnormal" than an average pup born with littermates. Others
said that singleton puppies were not problem pups until they
started to take notice of their surroundings. All of the breeders
interviewed had also produced pups with large litters and thus
had some basis for making the comparison. Most of the breeders
assumed that a singleton would be larger than normal thus producing
delivery problems, which resulted in a “C" section.
Veterinarians on the other hand reported a wide range of different
experiences that did not necessarily agree with those indicated
by the breeders. Most veterinarians said that a singleton
was not a larger, stronger or smarter pup then others of the
same breed when larger litters were produced. They also noted
that the singleton did not necessarily make a better companion.
Only a few reported that they noticed behavior problems even
though many-lacked interaction with other littermates.
Based on the experiences of these two groups the recommendations
that can be offered suggest a number of approaches. Apart
from having no littermates to interact with, the lack of companionship
could be compensated for if the dam is encouraged to provide
daily stimulation and attention. Puppies learn to be a dog by
being part of their "pack" in the nest. Keeping
the singleton occupied was found to be important and most recommended
handling by different individuals to keep them from becoming
bored. While most dams naturally encourage their pups to
play, they also teach them good manners. As soon
as these pups are old enough they should either go to their new
home (8 weeks is early enough), or have them introduced to the
owners other dogs.
Three breeders that had a singleton pup produced by frozen semen
were also contacted. All reported that the pups were of
normal size for their breed (Afghan Hound, Whippets, and German
Shepherd). The dams of these singleton puppies had produced
average litters before and after the singleton. The cause for
the singleton litter according to these breeders was the use
of frozen semen. All of the sires had previously produced average
size litters. The breeders of these frozen semen litters indicated
that it was just bad luck that only one pup occurred. All
of these singletons were born naturally except the one produced
from 16-year-old semen. Most of the dams had had a previous litter
naturally. The classic reason for singletons being born by Caesarian
does not seem to be related to the use of frozen semen.
The conclusion that one can draw from this material is that
breeders of a singleton should take extra care to be sure that
they are occupied and do not become bored. Since most dams can
only provide a limited amount of playtime these pups should be
given more opportunities to play with others (Malcolm Willis). Playgroups
were suggested as excellent ways for singletons to learn the
social rules of the canine species. All agreed that supervision
by humans should not be ignored because the singleton can be
injured during unintentional rough play.
The group was asked about the singleton when it had become an
adult. While this study was limited to several breeders and veterinarians.
They all agreed that the bitches involved in this limited study
were considered to be good mothers and had plentiful supplies
of milk. Most seemed to adore they’re one and only
pup and none were overprotective or lacking in interest. Some
were raised in the house as opposed to the kennel. Most of these
pups received more supervision and more early human socialization
than normally would have been provided while in the nest with
a litter. In order to fill the gap involving the lack of stimulation
some were placed with other litters. All grew to be normal
and healthy. Most but not all were considered well-adjusted adults.
It is not hard to see why swimmers and runts have several things
in common with the singleton. During the first few weeks after
birth they all tend to be hand raised. They are given so much
attention they can be categorized as being treated as a singleton. The
differences between them are that most swimmers and runts do
no grow up to look like their littermates and few ever become
good show or working dogs. Because they are given so much attention
and handling, the human bond generally is very good and most
make wonderful pets.
Based on a review of this complex subject and the answers gathered,
it seems fair to use a conclusion reached by Scott and Fuller
in the 1950's. While they did not study singletons and litter
size per se, they did study differences between breeds and individuals
within a breed. One of there conclusions was that there are measurable
differences between breeds that are both physical and behavioral.
They found that although there is a great deal of overlap between
breeds, the individual capacities they will have are likely to
be highly variable. They also found that most pups that become
great performers and able to perform extraordinary tasks seem
to have different capacities. In short, they "probably
have special combinations of certain capacities which are largely
the result of accidental selection".
References:
Goldbecker, W. and Hart, E., This is the German Shepherd,
T.F.H. Publications Inc. Jersey City, NJ 1964, p.125.
Kelley, Russ, Recent Advances in Canine and Feline Nutrition,
Vol. III, 2000 Iams Nutrition symposium proceedings; "Canine
reproduction: What should we Expect?" Orange Frazer Press,
Wilmington, OH 2000,
p. 225-239.
Severzov, Adrian and Owen, Ray, General Genetics, W. H. Freeman
and Company, San Francisco, 1957, p 503.
Scott, J.P. and Fuller, J. L., Dog Behavior, the genetic basis.
University of Chicago Press, Chicago, Ill.1965, p.366-367.
Trumler, Eberhard, Understanding Your Dog, Faber and Faber,
3 Queens Square, London. 1973, P. 56
Willis, Malcom, The German shepherd Dog: a genetic history, Howell
Book House, New York, 1995, p. 289-293.
| This article has
been reproduced with the kind permission of Dr. Carmen
L. Battaglia for the CFBA, the CIDBT, and their students
of Dog Behaviour & Training |
ABOUT THE AUTHOR
Carmen L Battaglia holds a Ph.D.
and Masters Degree from Florida State University. As
an AKC judge, researcher and writer, he has been a leader
in promotion of breeding better dogs and has written
many articles and several books.
Dr. Battaglia is also a popular TV
and radio talk show speaker. His seminars on breeding
dogs, selecting sires and choosing puppies have been
well received by the breed clubs all over the country.
Those interested in learning more about his seminars
should contact him directly. Visit his website at http://www.breedingbetterdogs.com
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