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Herbal Supplements for Dogs & Cats

Every day I have the privilege of helping pet owners try to say “NO” to drugs for their sick pets. I teach them to incorporate many therapies, such as homeopathy, diet, and herbal remedies, into the treatment prescribed for their pets’ ailments. One of the main reasons we work to incorporate supplements rather than conventional medications as part of the therapy is that in general, conventional medications have more side effects than natural therapies. Of course, it is the very rare therapy that can be considered totally safe. While many think that “natural” equals “safe,” this is certainly not true all of the time. Any therapy, be it a conventional drug or herb or nutrient, can have side effects. This is why I discourage owners from purchasing supplements for their use or their pets’ use without medical supervision. Sometimes the use of an herb or supplement can have a side effect by itself, whereas other times the herb or supplement might interfere with the actions of a conventional medication or increase the chance of side effects when used with a certain medication. Side effects can be directly related to the supplement or due to contamination of the supplement during processing (this is especially true with herbal remedies.)

To decrease the chance of side effects from contamination, it is important to only use products from reputable manufacturers. However, in most cases, when used correctly, natural therapies are less likely to have the side effects often encountered when conventional medications are used. For example, even short term use of NSAIDS can result in serious side effects, whereas natural joint supplements like glucosamine are generally used without harm to the patient. Here are some of the most commonly prescribed supplements and their side effects.

While I use herbs every day to help my patients, they can have side effects
which may be harmful. Therefore, I encourage you not to use any therapy,
natural or otherwise, without medical supervision.


Black Walnut
Black walnut is often used by pet owners as a natural deworming agent, especially to treat heartworm disease. While the history of the herb supports its use 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.

German Chamomile
Chamomile is well known for its sedative effects. Avoid in pregnant animals as it may cause abortion. Usually considered a safe herb, the rare pet may be allergic to chamomile.

Chaparral is reported to be an effective antimicrobial herb. However, ingestion of large amounts can lead to liver damage; avoid in pets with liver disease; potentially a very toxic herb and not usually recommended.

Red Clover
Red clover is used in many herbal cancer formulas due to its diuretic, blood cleansing, and anti-neoplastic effects. Red clover contains coumadin and should not be used in pets with blood clotting disorders. If fed in large amounts, the estrogenic components can be toxic. Do not use in pregnant animals. Red clover contains very small amounts of salicylic acid (aspirin,) and care should be used in pets taking corticosteroids or non-steroidal medications and in cats which are sensitive to salicylic acid.

Comfrey has been used for its anti-inflammatory and lubricating properties. Comfrey contains alkaloids that can cause liver damage or cance. 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 for any reason.

Echinacea is a well-known immune modulating supplement. For immune system disorders (autoimmune diseases, diabetes) and disorders with diminished immune systems with low white blood cell counts (feline leukemia and immunodeficiency diseases,) it was recommended in the older literature to avoid this herb as echinacea is used for immune stimulation. However, there have been no clinical studies supporting this recommendation, and echincacea has been safely used in people with these disorders. The older literature also recommended not using the herb for longer than 4-8 weeks without giving the body a “break,” but again this has not been substantiated clinically and it has in fact been used for longer periods of time without harm. Most veterinarians prefer to use echinacea early in the for course of the disease at the first signs of infection to properly and fully modulate the immune system. Caution is warranted in diabetics as the condition may become unstable.

Ephedra has a long history of use in Traditional Chinese Medicine as an effective therapy for respiratory (especially asthmatic) disorders. 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, most commonly prescribed for pets with asthma or respiratory problems, can cause heart arrhythmias and high blood pressure. Use with great caution in all pets. 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, pheochromocytoma, or hyperthyroidism.

Garlic has been historically 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. Do not use in pets with anemia. Garlic in high doses can prolong bleeding times. As a general guideline, 1 clove of garlic per 10 pounds of body weight for dogs (and 1/2 clove per cat) can usually be fed safely each day if the pet is not anemic.

Ginkgo Biloba
Ginkgo is well known for its use in treating mild forms of cognitive disorder and intermittent claudication in people. Ginkgo has antithrombotic activity via its PAF inhibition. Caution should be used if ginkgo is given to patients taking anticoagulant or antithrombotic medications (aspirin, NSAIDS.) It has been suggested that antiplatelet medications and herbs be stopped about 1 week prior to surgery. Rare reports of spontaneous bleeding (subdural hematomas, hyphema, subarachnoid for hemorrhage) are reported in the human literature, especially when combined with high doses of fish oil or other anti-clotting medications.. No reports are noted in pets. Do not use in animals with blood clotting disorders. Do not use in pregnant animals.

Kava Kava
Kava has a long traditional history of being a good calming, sedative herb. 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 hepatotoxicity, or where suffereing 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. Do not use in pregnant animals. May interact with anxiolytic medications (Valium, etc.)

Milk Thistle
Milk thistle is well-known for its treatment of liver disease. Do not use in pregnant animals. Long term use in normal animals may result in depressed liver function unless chronic liver disease is present. It is not recommended to use milk thistle to prevent liver disease.

This herb is used for its sedative effects. Do not use in pregnant animals. Excessive doses may cause sedation and potentiate the effects of drugs that are monoamine oxidase (MAO) 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
Tea tree oil is used topically for its antimicrobial effects. It can also help itching and control external parasites like fleas. It is generally recommended not to use most volatile oils in cats, or only do so with proper dilution and supervision. Small-breed dogs may also be sensitive to undiluted oil. The safest way to use this product is to only purchase properly prepared and already diluted products.

This herb is used for its sedative effects. Do not use it in pregnant animals. It can cause gastrointestinal upset in large doses. Do not use with similar medications (barbiturates or benzodiazepenes like Valium) without medical supervision as increased sedation may occur.

Like black walnut, this is another traditional deworming herb. It is considered unsafe for internal use in people without careful supervision. 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.

St. John's Wort
This is used as a natural sedative. Some pets may develop sensitivity to sun exposure, although this is unlikely in dogs and cats when used at recommended dosages. It may interact with other similar medications. Serotonin syndrome may occur if combined with SSRI medications. St. John’s Wort may interfere with the metabolism of medications administered with St. John’s Wort.




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