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Natural: Not Necessarily Safe
One of the great benefits of using natural therapies to treat pets is that they are usually much safer than conventional medications. However, any product, including a natural therapy, has the potential to cause toxicity. As I learned in toxicology class many years ago, the only thing that determines whether something is safer toxic is the dose.
Even though natural therapies tend to be safe, I prefer that pet owners consider them similar to medications, in that they should only be used under veterinary supervision. This will minimize toxicity as well as interactions with other supplements and conventional medications that may have been prescribed for the pet.
In this article I will focus on some of the more commonly used supplements that have the greatest degree of potential toxicity or those for which there may be some confusion regarding their safety.
Black walnut is often used by pet owners as a natural deworming agent, especially for heartworm disease. While it is a popular herb to treat parasites, there is no consistent proof of its use as a single agent to treat heartworm infection. This herb is usually considered too toxic to use without veterinary supervision. The tannins and alkaloids may lead to vomiting and diarrhea. Most conventional dewormers (and other herbal deworming preparations) are much safer.
Chaparral is recommended to treat infections. However, ingestion of large amounts can lead to liver damage. It is considered a very toxic herb and not usually recommended.
Comfrey is recommended for its anti-inflammatory and lubricating properties. Comfrey contains small quantities of alkaloids that can cause liver damage or cancer if taken in large quantities. While the leaves (the most commonly used part of the herb) contain almost negligible amounts of alkaloids (the roots contain the most and should never be used,) many doctors consider it too toxic to use.
Ephedra has a long history of use in Traditional Chinese Medicine as an effective therapy for respiratory (especially asthmatic) disorders, even though it is incorrectly and commonly used as a weight loss supplement in people. While it has been reported that cats may exhibit idiosyncratic reactions, I have not had any side effects in cats treated with ephedra for upper respiratory disease. Ephedra can cause heart arrhythmias and high blood pressure, and commonly does so in people. As with all herbs, it should be used with great caution in all pets and only under veterinary supervision. It should not be used when medications which have similar actions are used (MAO inhibitors, sympathomimetics) or in pets with hypertension, cardiac arrhythmias, anxiety, restlessness, glaucoma, cardiovascular disease, impaired cerebral circulation, prostatic adenoma with residual urine accumulation, pheochromocytoma, or hyperthyroidism.
Fish oil is a common anti-inflammatory substance for use in pets with a variety of problems including allergies, arthritis, heart disease, kidney disease, and cancer. It must be used at high doses (much higher than the label dosage) in order to be effective. In people, there have been rare reports of bleeding in the brain when used in very high doses or combine with other anticoagulant drugs or supplements. To date, this has not been seen in pets and it is very unlikely that similar high doses would be used in pets for any purpose.
Garlic is recommended for many uses, including the treatment of parasites, microbial infections, and in the treatment of cancer. Garlic in large amounts can cause Heinz body anemia in dogs and cats due to the presence of S-methyl cysteine sulfoxide and N-propyldisulfhide and should not generally be used in pets with anemia. Garlic in high doses can prolong bleeding times.
Glucosamine is a common ingredient in many joint supplements. While safe, there have been some concerns expressed about its use in animals with diabetes as it contains glucose. To date, it is safe to use AT THE PROPER DOSE, in all animals, even those with diabetes.
Kava has a long traditional history of being a good calming herb. It can be toxic to the liver in excess amounts and it should not be used in pets with liver disease. There have been recent reports of liver toxicity and death in depressed people treated with this herb. However, careful analysis of these reports revealed that these patients had preexisting liver disease, were taking drugs with potential liver toxicity, or were suffering from chronic alcoholism. The herb has a long history of safety but it is recommended to screen for liver disease before using the herb and to periodically monitor liver enzymes if the herb needs to be given for long-term use. It may interact with similar medications.
While pennyroyal oil is an effective insecticide, due to potential severe toxicity and death pennyroyal oil is not recommended for use in pets.
Tea tree oil is used topically for its antimicrobial effects. Undiluted oil is toxic; properly diluted oil is safe. Wormwood-This is another traditional deworming herb but as with black walnut it can be toxic. Do not use in pets with seizures, kidney disease, liver disease, or in pregnant animals. Safer herbs for deworming exist and wormwood should only be used with extreme caution under veterinary supervision.
St. John's Wort
This is used as a natural sedative. Some pets may develop sensitivity to sun exposure. It may interact with other similar medications and serotonin syndrome may occur if combined with SSRI medications.
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