The dogs of war
by Peter Montague, reprinted from Rachel's Environment & Health Weekly,
#436, April 6, 1995
The study of dogs that served - and died - serving in Vietnam provides
important information on toxic chemicals that can help direct health policy
in the United States
omewhere between 2.6 and 3.8 million American men and
women served in Vietnam during the years 1965 through 1971, the years when
chemical herbicides were being used to denude the jungle and destroy enemy
crops. Military records do not allow a more accurate determination of the
true number who served.
Alongside the humans serving in Vietnam, there were
3,895 military working dogs, almost all of them purebred German shepherds.
These dogs served as scouts, sentries, trackers, mine detectors, and tunnel
explorers. About 91% of these dogs were "intact" (uncastrated)
When a military working dog dies, regardless of the
circumstances of death or the duty location, an autopsy is performed by
a veterinarian, and a standardized set of tissue specimens and organs are
sent to the Armed Forces Institute of Pathology in Washington, D.C.
During the late 1980s, researchers compared autopsy
records of 1,167 military working dogs with Vietnam service with autopsy
records of 791 military working dogs who served in the continental United
States and saw no Vietnam service. In a separate study, the stateside dogs
were also compared to 437 dogs that died in Okinawa, because many dogs that
served in Vietnam were sent to Okinawa after the war.
These studies showed that dogs who served in Vietnam
were about 1.8 times as likely to have cancer of the testicles, compared
to military working dogs who served only in the states. Similarly, military
dogs that died in Okinawa were about 2.2 times as likely to have testicular
cancer as dogs who served only in the states. A separate study was then
conducted, excluding the dogs who had testicular cancer. Among the non-cancer
dogs, there was clear evidence of significant deterioration of the testicles
in those dogs who served in Vietnam: degeneration of the testicles, atrophy
of the testicles, and evidence of a below-normal ability to produce sperm.
Dogs have often served as sentinels of human disease.
In 1938, well-known researcher W.C. Hueper showed that beta-naphthylamine
caused bladder cancer in dogs. In 1954, researchers showed that another
industrial chemical, 4-aminodiphenyl, produced bladder cancer in dogs. In
1980, a study of 8,760 pet dogs showed that bladder cancer in dogs correlated
with residence in industrialized counties in the United States and Canada;
this same study showed that bladder cancer in men and women was similarly
correlated with residence in industrialized areas. "The findings of
this study suggest that the bladder cancer experience of pet dogs resembles
that of human beings living in the same general locale," the study
Pet dogs are particularly relevant in such studies.
Forty million pet dogs share their owner's domestic environment but don't
indulge in behavior that could confuse or confound the interpretation of
epidemiological studies: dogs don't smoke, and they usually don't work.
In 1983, a study of pet dogs with the asbestos-related lung disease, mesothelioma,
showed that their disease correlated with household members who worked in
an asbestos-related job, had an asbestos-related hobby or applied flea powder
to their dog.
For these reasons, the finding of testicular cancer
and testicular dysfunction in dogs who served in Vietnam was an eye-opener.
It soon led to a comparison of 271 human veterans with testicular cancer
to 259 veterans without testicular cancer, to see whether Vietnam service
was related to testicular cancer. This study revealed that, like dogs, human
veterans of Vietnam were 2.5 times as likely to have testicular cancer compared
to veterans who did not serve in Vietnam.
What aspects of military service in Vietnam caused testicular
cancer in men, and testicular cancer and dysfunction in military working
An obvious suspect is Agent Orange, 11.2 million gallons
of which were sprayed over 3.6 million acres of Vietnam. Agent Orange, named
for the orange stripe on its 55-gallon storage containers, is a 50-50 mixture
of two herbicides: 2,4,5-T and 2,4-D. One of these, 2,4,5-T, was banned
in the United States around 1980 following evidence that it could cause
birth defects in humans. The second component, 2,4-D, remains in wide use
throughout the United States where it is popular for killing dandelions
and other broad-leaf plants in lawns, and as an agricultural weed killer.
During manufacture, the herbicide 2,4,5-T unavoidably
becomes contaminated with dioxin. According to the National Academy of Sciences,
the average dioxin contamination in Agent Orange in Vietnam was 2 parts
per million (ppm). An estimated total of 368 pounds of dioxin was sprayed
onto Vietnam's land and people during the seven-year spraying program.
However, a recent study of Vietnam veterans that tried
to estimate 2,4,5-T exposure and link it to testicular cancer found that
only Navy men had elevated levels of testicular cancer associated with 2,4,5-T
exposure; men in the other services showed no such effect of exposure. The
authors of that study speculated that Navy men might also have been exposed
to fuels (oil and gasoline), which previous studies have linked to testicular
The other half of Agent Orange, herbicide 2,4-D, is
also a suspect. Although the manufacturers of 2,4-D claimed for years that
their products were not contaminated with dioxin, this claim has now been
shown to be false, using the manufacturers' own data. Dioxin has been shown
to damage the reproductive organs and systems of many animal species, including
men and women.
A study of pet dogs in the United States found excess
cancers associated with 2,4,-D lawn spraying. A study of 32 farmers who
sprayed 2,4-D, compared to a control group of 25 unexposed farmers, revealed
significant effects on the exposed farmers: diminished sperm count, increased
number of sperm with poor motility (swimming ability), increased numbers
of dead sperm, and increased numbers of malformed sperm.
No federal agency keeps close track of pesticide use
in the United States. However, the Environmental Protection Agency estimates
that U.S. farmers apply 25 to 30 million pounds of "active ingredient"
of 2,4-D each year. Non-agricultural use of 2,4-D in the United States is
estimated at 12 to 15 million pounds of "active ingredient" per
year. (The "active ingredient" of a pesticide is only 0.5% to
5% of the total formulation so these "active ingredient" amounts
must be multiplied by anywhere from 20 to 200 to get the total volume of
2,4-D formulations used each year. The bulk of the formulations are secret
ingredients called "inerts" which are, themselves, often toxic
Other chemicals suspected of causing testicular cancer
and dysfunction in dogs and humans who served in Vietnam are the antibiotic
tetracycline and the pesticide malathion. Many military dogs in Vietnam
suffered from ear infections and other diseases, and received one or more
doses of tetracycline during their tour of duty. Tetracycline is strongly
absorbed by sperm in mammals, and is known to cause testicular atrophy,
and diminished sperm quality in humans and dogs.
The other suspicious candidate is malathion. The same
military units that sprayed Agent Orange also sprayed DDT and malathion
extensively in the vicinity of U.S. troops to reduce the dangers of malaria
carried by mosquitoes. It has been reported that 44 percent of the land
of southeast Asia, mainly Vietnam, was sprayed with malathion during the
war. Furthermore, military working dogs in Vietnam were dipped in a 0.5
percent solution of malathion to kill disease-carrying ticks. Malathion
is known to cause testicular atrophy and damage to the sperm-generating
cells of laboratory animals.
Malathion is currently widely used throughout the United
States for mosquito control - though not for fear of malaria. Mosquitoes
are simply a nuisance. EPA estimates that 4 to 6 million pounds of "active
ingredient" of malathion are sprayed in the United States each year.
The annual total of malathion formulations sprayed is, again, 20 to 200
times this amount.
Sperm count in men throughout the industrialized world
appears to be dropping. Testicular cancer is the most prevalent cancer among
white males between the ages of 25 and 34 years and the second most common
in the 35-to-39 age group. The causes of testicular cancer are thought to
be environmental because the rates vary widely from one location to another.
During the past 15 years, the rates have increased rapidly (2.3 to 3.4 percent
per year) in many industrialized countries.
It may take scientists many decades to tell us all we
would like to know about a complex chemical like dioxin or malathion. However,
we already know enough to act. To guide our personal choices and new public
policies, to minimize the danger to ourselves, our families, and our communities,
we need only to remember that chemicals not used cannot cause harm. This
we can learn from the dogs of war.
Rachel's Environment & Health Weekly is published by Environmental Research Foundation, providing information on toxic substances, their impact on human health and communities, the corporations and technologies that produce them, and alternatives. The newsletter covers many technical issues written in plain language that anyone can understand. For subscription information, contact the Foundation at P.O. Box 5036, Annapolis, MD 21403; Fax (410) 263-8944; Internet: erfrachel.clark.net