Sclerosis and Fibrosis Experiments
- Young white leghorn chickens inbred at the
University of California-Davis develop an inherited fibrotic disease
in their combs that spreads through their systems. Researchers
see this as having a resemblance to human progressive sclerosis,
a connective tissue disease of unknown cause characterized by
fibrosis of the skin and internal organs (Water and Gershwin).
- Broiler chickens (6 week-old baby birds slaughtered
for meat) fed an essential fatty acid deficient diet (EFAD) were
evaluated as a model for cystic fibrosis. According to researchers,
the results showed that essential fatty acids are necessary to
maintain proper lung function, thus making the chicken a model,
in this respect, for studying the relationship between EFAD and
pulmonary disease in cystic fibrosis patients (Craig-Schmidt).
Diet and Nutrition Experiments
- Pigeons fed cholesterol in their diet show an increase in serum
lipids and arterial lesions causing heart attacks, resulting in
the frequent use of these birds in atherosclerotic
and other metabolic studies considered applicable to humans (Ediger).
- Because of their extreme susceptibility to
vitamin deficiencies, young chicks are used to check the validity
of chemical and microbial methods of measuring vitamins in foods.
Experiments with chicks and chick embryos deprived of vitamin
B12, for example, have been used to predict the likely effects
of vitamin B12 analogues. In addition, the specialized requirements
of birds for vitamin D have made the chick a preferred model in
studies of the physiological forms and function of vitamin D (Coates).
- Researchers at the University
of Wisconsin in Madison have found that laboratory chickens and
mice infected with a human virus, adenovirus-36, put on much more
fat than do uninfected chickens and mice, making this virus “the
first human virus that has been shown to cause obesity in animals.”
They caution that “far more research is needed before any practical
benefits can be reaped from this research” like whether it may
be possible to develop a vaccine against human obesity (Crenson).
Muscular Dystrophy and Muscular Performance Experiments
- Specially-bred chicks and ducks are considered with mce as
possible models for studying the basic pathogenic mechanisms of
muscular dystrophy. This “spontaneous” disease of inbred stocks
of white Pekin ducks and chickens is said by researchers to show
features resembling those of the human body (Gopalakrishnakone)
- Interested to find out whether static muscular contractions
in birds act the same as those in humans and other animals, two
University of California-Davis researchers funded by the American
Heart Association experimented on thirteen white leghorn male
chickens, three to four weeks old (Solomon and Adamson). The researchers
recommended the use of chickens because “[f]irst, they are far
less expensive” than other birds, and second because they are
easy to obtain in large quantities (p. R764). After anesthetizing
them with chloralose, the researchers stuck tubes in the birds’
ulnar (wing) vein, left carotid artery, and cervical trachea.
They ruptured the clavicular air sac (part of the chicken’s respiratory
system) and pumped oxygen, carbon dioxide, and nitrogen into the
birds’ lungs. They inserted a thermistor probe into their colons.
They pinned the birds down to cut their muscles and attach other
machinery to them. They exposed the sciatic nerve in the birds’
hips, induced paralysis, and electrically stimulated the exposed
sciatic nerve of the hip. They measured blood pressure and heart
rate responses to static contraction of the gastrocnemius (leg)
muscle. Fifteen minutes later they repeated the experiment. The
results showed that static muscular contractions increase arterial
blood pressure and heart rate in chickens the same as in humans
and other animals: “We have provided good evidence for the existence
of an exercise pressor reflex in chloralose-anesthetized chickens”
(Solomon and Adamson, p. R759).
- To “solve the puzzle” of how muscles and tendons work together
when humans and other animals run, Princeton University researchers
implant tiny strain gauges and electrical flow sensors into the
legs of wild turkeys and make them run on treadmills. They claim
that turkey treadmill experiments have “important consequences”
for physical, occupational and rehabilitative therapy as well
as for the design of prostheses, selecting appropriate animal
models for experiments involving the musculoskeletal system, and
for rehabilitating injured people or training elite athletes
(Taylor; Roberts et al.). Emus and many other animals are used
in treadmill studies (Solomon and Adamson, R759).
Visual Impairment Experiments
The superb visual organization of birds has targeted
them as models for experimental investigations of eye abnormalities
in humans. For example, severe myopia (nearsightedness) is artificially
produced in chicks with techniques and devices that blur their vision
including altering the amount of light and fitting their eyes with
lenses (Dayton; Seachrist). Concerning one of these studies, an
article in Science News noted that while the eyes of
chicks “wearing spectacle lenses to simulate nearsightedness” grew
to compensate for blurred vision, the fact that chick eyes “develop
very differently from human eyes” required the use of tree shrews
to indicate that the “eyes of higher [sic] animals also grow in
response to blurred vision” (Seachrist, p. 318).
Another technique for turning birds into models
of human eye abnormalities in humans is eye suture, which may also
include eye implants. Eye suture is performed by excising the upper
and lower lid margins of a bird’s eye, often involving far more
extensive operations (Seachrist, pp. 318-319).
Surgical Experiments
White domestic geese have served as models for
intraocular (eye) surgery, and broiler chickens have been used to
test the effects of surgical drilling and curettege (the scraping
of body cavities and tracts) in acute hematogenous staphylococcal
osteomyelitis, a human bacterial bone disease that is experimentally
induced in the birds by inoculation (Emslie and Nade).
Sex-Change Experiments
Researchers interested in how genes interact
with hormones to determine sex, inject hormone-altering enzymes
into chickens inside the egg. Of the hundreds of enzyme-treated
eggs containing genetically female embryos, the majority look like
males after hatching. Half of the females in a study reported in
Science in 1992 “grew up to look and behave like roosters,
even developing testes and producing sperm” (B.R.).
Organ Development and Deformity Experiments
Claiming their research could “one day help to
repair damaged organs or even generate new ones in the laboratory,”
including new teeth, a team of Harvard researchers reported inserting
a substance involved in the development of mouse teeth, called BMP4,
into the jaws of chick embryos to show that tooth buds can be made
to develop in birds (Wade 2000). This research (which is said to
be going on elsewhere as well) is linked to other experiments in
which the gene for mouse teeth is “knocked out” (deleted), creating
mice with few or no teeth, a field in which researchers claim to
be making “brisk progress.” The “hen’s teeth” experiment, which
was reported in The New York Times on August 22, 2000,
appeared in that day’s issue of the Proceedings of the National
Academy of Sciences (Wade).
In an experiment at the University of British
Columbia, a research team headed by Dr. Joy Richman, a pediatric
dentist at UBC, blocked the activity of a protein that stimulates
bone growth in chickens and added a vitamin A-derived acid. Richman
made a hole in an eggshell and put microscopic protein-soaked beads
on the embryo’s face. Two weeks later, the fetal chick had two beaks.
The next step is “to have genes send different signals to grow other
parts” of chickens’ faces. This hit-and-miss scramble of facial
features in chickens “could help scientists understand normal facial
development and what causes facial deformities” (Lee).
Trans-Species Brain Transplants
A story in Sciencemag.org says that
University of Illinois neurobiologist Thomas Park claims to have
transplanted an inborn behavior from one species to another by putting
brain tissue from quails into young chickens, causing the chickens
to prefer the sounds made by mother quails over those made by mother
chickens. Park called this outcome “a real breakthrough in the study
of perceptions, which are very elusive brain functions to study”
(Withgott).
Aging Experiments
Entitled “Birds as animal models for the comparative
biology of aging: a prospectus,” published in the Journal
of Gerontology (1995; Vol. 50a [Biological Sciences]: B59-66),
the authors, Donna J. Holmes and Steve N. Austand from the Department
of Biological Sciences at the University of Idaho, call for the
use of birds as research models for human aging. They suggest that
“a number of commercially available bird species would lend themselves
to laboratory studies of aging. Because they consist mostly of psittacines
(parrots and their relatives) and finches bred and raised by professional
pet bird breeders, their husbandry is well understood. The smaller
species are inexpensive and easy to maintain; several are easily
bred in captivity, including budgerigars, zebra and society finches,
and canaries. Finches and canaries are already extensively used
in neurophysiology and behavioral biology. Some wild passerines
are also easily trapped and adapt readily to captivity, and have
been used very successfully in studies of avian endocrinology and
nutrition. Small passerines, particularly finches, should be no
more costly to maintain than laboratory mice.” They conclude that
“There seem to us to be few intrinsic barriers to the development
of several avian ‘mice’ -- extensively characterized species exhibiting
exceptionally long life and retarded aging.”
Pain Experiments
“The close similarity between birds and mammals in their physiological
and behavioural response to painful stimuli argues for a common
sensory and emotional experience. It is therefore essential that
the ethical considerations normally granted to mammals be extended
to birds.”
—Michael J. Gentle 1991
“Comparing pain in birds with mammals, it is clear that,
with regard to the anatomical, physiological and behavioural parameters
measured, there are no major differences and therefore the ethical
considerations normally afforded to mammals should be extended in
birds.”
— Michael J. Gentle 1992
“Previously reported methods for measuring nociception
[pain] in domestic fowl differed in various ways but in each instance
some form of restraint accompanied the assessment procedure. . .
. Our purpose of the present research was to examine the ontogeny
of nociception in domestic fowl with a procedure that involves confinement
but not restraints. Preliminary research indicated that the ‘hot
plate’ technique, often used to index nociception in mice and rats,
might be used similarly for research on nociception in domestic
fowl.”
This “noxious thermal stimulus” research (“the
first to examine nociception systematically in domestic fowl within
a developmental context") was conducted by Richard A Hughes
and Kenneth J. Sufka in the Department of Psychology at Iowa State
University in 1989. It consisted of three experiments in which approximately
300 white leghorn male chicks from one day old to two weeks old
were confined to hot plates of 59, 61, or 63 degrees C to see whether
the chicks jumped faster as the grids grew hotter, whether baby
chicks jumped faster or slower than older chicks, and whether socially-raised
chicks jumped faster or slower in response to the hot plates than
chicks raised in isolation (Hughes and Sufka 1990).
This same Richard A. Hughes, cited above, published
another study in 1990 in which chicks were administered codeine
or morphine, and then put on hot plates. He showed that chicks on
morphine jumped sooner than chicks on codeine (Hughes 1990). Other
Hughes research listed in his References section includes the use
of other drug combinations or electric shock to show pain and behavioral
responses in chicks, and studies in which drugs and electric shocks
were administered simultaneously to test their effect on tonic immobility
(in which birds “freeze” in response to predators and fear) in chickens.
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