Historical Health Study
From Purdue University
While researching health information for one of the CMTC’s
ongoing health surveys, an interesting historical health study came to light and
the Health Committee felt it would be of interest to club members. The CMTC
Health Committee, in particular Dr. Jennifer Tomes, prepared this article.
The study in question examines the incidence of disease in
specific breeds based on the Veterinary Medical Database (VMDB) at Purdue
University, compiled over a 30-year period (1965 – 1995) by animal veterinary
colleges. The source of the data is veterinary teaching hospitals at
twenty-three US universities and one Canadian university. The study notes that,
because the patients seen at these teaching hospitals were often referrals of
more difficult cases, data in the survey might not reflect the data in the
general pet population. Nonetheless, the data is historically interesting.
Breeds with less than 1000 total cases were not used, so
the VMDB includes 78 breeds in the study. The analysis included the top 10
diseases for each of the 78 breeds and for the purposes of this article we are
focusing entirely on Manchester Terriers.
To help you interpret the study table data for Manchester
Terriers, it is necessary to understand the concept of Odds Ratio used in the
study. Think of it as an index of how likely Manchester Terriers are to have a
particular disorder compared to other breeds as experienced by the teaching vet
hospitals in the study. If the Odds Ratio equals 1, it means the particular
disease occurs at the same rate as in these other breeds. If the Odds Ratio is
less than 1, the disease occurs less often than in other breeds. For example,
for Eye Disease (Other), Manchester Terriers have an Odds Ratio of 0.33, which
means they only have 1/3 of the risk of developing that disease compared to
these other breeds. If the Odds Ratio is over 1, it means the disease is more
common and the number indicates the level of risk. For Manchesters, diabetes is
ranked at 8.81, which means that Manchesters have a rate of diabetes almost 9
times that of the other breeds in the database.
The study lists the top 10 diseases for each breed, ordered
by the Odds Ratio. We can see the top 10 diseases for Manchester Terriers and
how the incidence in Manchesters compares to the other breeds in the survey.
Please remember, this study does not compare the rate of disease in the entire
Manchester population against the rate of disease in the entire general dog
population. It only looks at the rate of specific diseases treated by
participating veterinary teaching hospitals.
Further statistics such as confidence intervals and P
factors have been omitted from this table for clarity. Please refer to the
actual study, located at
http://www.akcchf.org/research/articles/whitepapers/risk.pdf for more
detailed statistics.
VMDB -- Manchester Terrier
Disease No. Of Cases
Odds Ratio
Alopecia
19 10.55
Diabetes mellitus 30 8.81
Demodectic mange 22 3.03
Perianal gland disease 22 2.92
Heart disease (see note 1) 44 1.75
Dental calculus 43 1.18
Cataract 39 0.86
Dermal disease, other 19 0.71
Dermatitis, allergic 42 0.37
Eye disease, other 21 0.33
Note 1: Heart disease included cardiomyopathy and heart
murmurs.
It is interesting to view this historical survey in context
with the more recent (and more detailed) CMTC/AMTC General Health Survey of
2001.
Summary Table
CMTC/AMTC
General Health Survey
Most Common Non-Infectious Diseases Most
Common Non-Infectious Conditions
vWD
2.72% Coprophagia
13.51%
Heart Murmur 2.72% Puppy
Mange 6.22%
Hypothyroidism
2.62% Gingivitis
4.86%
Deafness 1.46% Impacted
Anal Glands 3.40%
Legg-Calve-Perthes 1.46% Monorchidism
3.21%
Cataracts 1.36% Seasonal
Alopecia 1.85%
Cardiomyopathy
1.26% Localized Demodex
1.85%
Luxated Patella 1.17% Umbilical Hernia
1.75%
While it is difficult to compare the two surveys
because of differences in
how the
data was collected, it is
none-the-less interesting to note
some key
similarities and
differences between the studies. For example,
both studies found elevated levels of heart disorders, mange,
tooth/mouth problems such as gingivitis, and perianal gland
disease (impacted anal glands), indicating these disorders continue to be
problematic for today's Manchester Terriers.
There
are also interesting differences between the findings of the two studies. Of
particular interest, is the absence of such diseases as vWD in the
historical survey and conversely, the lack of diseases such as diabetes in the
more recent General Health Survey.
It is likely that vWD is absent from the historical survey as it is not a
disorder that likely would have involved many referrals to veterinary colleges
which were the source of the data for the VMDB study. However, the
reason behind the
differences between the prevalence rates for diabetes between the two studies
is less clear.
One can hope
that
this disease is on the decrease in Manchester Terriers
and that the CMTC/AMTC Health Survey more accurately represents the presence of
this disorder in current Manchester Terriers.
Thyroid disorder is another disease reported in the CMTC/AMTC study that is not
represented in the VMDB study. Once again, the question
that
arises is,
is this because in the past Manchester Terriers suffering from thyroid problems
were treated by their own veterinarians and not referred to veterinary colleges
for further treatment or is it because the disorder is on the rise in the breed?
Unfortunately
this question
cannot be answered with the existing data.
The VMDB included data for over 1000 Manchester Terriers
over a 30-year period. It
will be extremely interesting to view the data from additional
General Health Surveys to see if the disease trends remain constant with the
original General Health Survey in 2001.
