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Hieronder een artikel over mycotoxins, helaas in het Engels
Dogs and cats are scavengers to some degree and therefore capable of
handling bacteria and other impurities in their food. However, the waste
products of fungi molds, called mycotoxins, are increasingly being
implicated as causes of both acute and long-term health problems in pets
and their human caregivers as well.
In January 2003, The Council for Agricultural Science and Technology
(CAST) released a scientific task force report, Mycotoxins: Risks in
Plant, Animal, and Human Systems. "We are just beginning to realize the
impacts and to be able to assess the economic burden that a few
mycotoxins cause in the United States through losses in commodity
quality and health of livestock. In the United States alone, it is
estimated that the economic costs resulting from mycotoxins exceed 1.4
billion dollars. These economic aspects are examined in this new CAST
report," said Dr. John L. Richard of Romer Labs, Inc. of Union, Missouri
and co-chair of the task force of scientists who prepared the CAST
report. "We also know that there are numerous other mycotoxins
throughout the world that have similar economic effects and threaten the
health of humans, and these also must be addressed to assess the full
impact of mycotoxins on a worldwide basis."
Fungi, Molds and Mycotoxins
Fungi are single cell living forms of life, which inhabit the land, air,
and waters of our planet. They are everywhere in our environment, soil
and home. Fungi are more highly developed than bacteria and viruses.
They are composed of many more species than are found in other
microorganisms. Fungi have been on earth several billion years and,
quite remarkably, have had little genetic change over that period of
time. They are survivalists. They can change their form from rapidly
growing to no growth for thousands of years, such as seen in their
living spores which have been found in Egyptian tombs. It is estimated
that there are over 2 million species of fungi, of which approximately
600,000 have been identified to date. Most fungi generally are not
pathogenic to healthy humans and animals. However, some fungi adversely
affect health through three processes 1) allergy; 2); infection; and 3)
Fungi produce metabolites. During colonization fungi secrete enzymes to
digest organic materials into simpler compounds. The simpler compounds
are primary and secondary metabolites. The secondary metabolites are
called mycotoxins. These metabolites give molds competitive advantages
over other surrounding molds growing in the same proximity.
Mycotoxicosis can be defined as illness resulting from ingestion,
inhalation, or other involvement with mycotoxins. In nature, mycotoxins
are a defense for fungi and provide advantage when colonizing new strata.
It has been estimated that at least 25% of the grain produced each year
worldwide is contaminated with mycotoxins. Modern farming techniques are
partly responsible for the increasing mycotoxin problem but mycotoxin
production may also occur during processing, transport or storage. Warm
ambient temperatures and high humidity favor mycotoxin production. Any
activity that disturbs the stability of an ecosystem will increase the
production of mycotoxins.
Mycotoxins, or their metabolites, can be detected in meat, visceral
organs, milk and eggs. If a livestock species that is tolerant to a
particular mycotoxin is fed a contaminated diet, there is a potential
for the "carry-over" of toxin into animal products, such as milk or
meat, destined for the super market. Mycotoxin concentration in food is
usually considerably lower than the levels present in the feed consumed
by livestock animals and unlikely to cause acute intoxications in
humans. However residues of carcinogenic mycotoxins, such as aflatoxin
B1 and M1, and ochratoxin A, when present in animal products can pose a
threat to health. The alternative would be to purchase only grass-fed
meat and animal products. In most instances the principal source of
mycotoxins for humans and pets is contaminated grains and legumes rather
than animal products. With respect to grains, it really doesn’t matter
if it’s organic or not if the grain has been stored for months; either
way, it stands the chance of being contaminated with fungi and mycotoxins.
Mycotoxins and Dry Pet Food
New mycotoxins are being discovered at a high rate. The major classes of
mycotoxins with which pet owners need to be concerned in dry pet foods
are aflatoxins, trichothecenes (includes deoxynivalenol (DON) or
vomitoxin), fumonisins, zearalenone, ochratoxin and ergot alkaloids.
Aflatoxin, a mycotoxin produced by Aspergillus species, can produce
varying degrees of toxicity. Corn, peanuts, and grains are potential
sources of aflatoxins in pet foods. Dogs and cats are among the species
most sensitive to the effects of aflatoxin. The onset and severity of
the clinical syndrome depend on the dose and duration of exposure. In
1955, the canine disease known as hepatitis X was successfully
reproduced by feeding dogs a brand of dog food previously incriminated
in cases of the same disease. Later, researchers discovered that the
identical syndrome could be elicited in dogs fed purified aflatoxin B1.
The principal target organ in all species is the liver. Clinical signs
such as anorexia, severe gastrointestinal disturbances, jaundice and
hemorrhage, with corresponding increase in hepatic enzyme activities and
a decrease in serum protein values are typical. Aflatoxins are heat
stabile and not destroyed by pet food manufacturing methods.
Vomitoxin (DON) is a mycotoxin produced by members of the genus Fusarium. Vomitoxin can be found in any grain but most commonly affects wheat and barley. Like most other mycotoxins it is heat stable. Dogs and swine are the species most susceptible to the effects of vomitoxin and at relatively low concentrations. Clinical signs include refusal of food, vomiting and diarrhea. The advisory level for DON in grains and grain by-products used in pet foods is 5ppm with the added recommendation that these ingredients do not exceed 40% of the food (i.e. 2ppm DON in the complete pet food). However, food refusal in dogs has been reported in levels approaching 2ppm. Humans are allowed 1ppm vomitoxin. Grain may constitute 1/3 or less of the human diet. On the other hand, grain may constitute up to 1/2 of a dog’s kibble diet.
Fumonisins are a group of recently described mycotoxins produced by
Fusarium moniliforme, a common field fungus found in grains, beans and
fruit. Little information is known about the toxicity of F.moniliforme
in dogs and cats. However, these potent mycotoxins cause equine
leukoencephalomalacia and liver disease in a number of other species.
Although canine and feline toxicity data for many other foodborne
mycotoxins are limited in scientific literature, the toxic effects of
penitrem A, rubratoxin B, ochratoxin A and cyclopiazonic acid (CPA) have
been described and documented.
Mycotoxins and Disease
Mycotoxicosis, the disease resulting from exposure to a mycotoxin may range from acute to chronic. Toxicity symptoms range from mild gastrointestinal discomfort, diarrhea and vomiting to rapid death. Small amounts of mycotoxin-contaminated food may be consumed in dry dog food. Long-term, low level exposure can produce vague symptoms such as a decrease in overall well-being to chronic damage to organs such as liver cirrhosis, immunosupression, and tumor formation.
Mycotoxins may cause:
* Gastrointestinal Problems: slowdown, delayed stomach emptying,
stasis/colic, hemorrhages of the large intestine, shock, reduced
gastric and small intestine flow, necrosis of the GI tract, severe
bloating, impaction, shutdown without blockage, refusal to eat,
weight loss, increased water consumption, vomiting, enteritis.
* Internal bleeding, hemorrhages or bruising.
* Stomach ulcers, mouth sores.
* Kidney damage (nephrotoxicity).
* Liver damage (liver lipidosis, hepatic lesions/fibrosis/swelling,
degenerative changes and dystrophy).
* Central nervous system problems (twitches, wobbling, convulsions,
seizures, paralysis, spasms, tremors, incoordination, depression,
* Immunosupression (increased susceptibility to multiple bacterial
and viral infections).
* Cancer (tumorigenesis).
* Eye problems (discharge, corneal ulcers, keratitis).
* Lung problems (pneumonia, lung lesions, pulmonary fibrosis,
hemorrhages, respiratory distress, bleeding).
* Glandular problems (hypertrophy of the adrenal cortex glands).
* Reproductive organ problems (impaired ovarian function, cystic
ovarian degeneration development, reproductive disorders, vaginal
* Heart problems (damaged heart muscle, tachycardia).
* Skin problems (skin rash, ulcerations, lesions, burning sensation,
sloughing of skin, photosensitization).
* Bone marrow and spleen problems (depletion/irreversible
damage/necrosis of the myelopoietic cells in bone marrow and in
splenic red pulp).
* Blood abnormalities (decrease in blood coagulation, hematocrit and
white blood cell count, leukopenia, calcium-phosphorus imbalance).
* Rectal prolapse.
* Vascular system (increased vascular fragility, hemorrhage into
body tissues, or from lung).
* Caustic effects on mucous membranes.
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