In pets combination
products containing multiple ingredients are more often
prescribed than individual herbs. However, having an
understanding of the individual herbs contained in the
product can help the owner understand why the herb was
included in the product. In people, St Johns Wort is often
used to help control mild depression. In pets the herb is
used as part of anti-anxiety formulas.
The active components
in St Johnís wort are found in the buds, flowers, and newest
leaves. Extracts are usually standardized to the substance
hypericin, which has led to the widespread misconception
that hypericin is the active ingredient. However, there is
no evidence that hypericin itself is an antidepressant.
Recent attention has focused on another ingredient of ST
Johnís wort named hyperforin as the potential active
It appears that
standard ST. Johnís wort extract contains about 1 to 6%
suggested that St. Johnís wort works like the oldest class
of antidepressants, the MAO inhibitors. However, later
research essentially discredited this idea. More recent
research suggests that ST. JohnísWort may raise levels
of serotonin, norepinephrine, and dopamine. This probably
increases neurotransmitters to maintain normal mood and
emotional stability (the herb may also cause binding of GABA
and act as a serotonin reuptake inhibitor.) Studies have
used the standardized extract containing 0.14% hypericin.
Evidence from animal
and human studies suggests that hyperforin is the ingredient
in St Johnís wort that raises these neurotransmitters.
However, there may be other active ingredients in ST .
Johnís wort also at work.
The herb has been
recommended for depression, separation anxiety, and certain
forms of aggression in pets.
In people, ST . Johnís
wort is one of the best-documented herbal treatments,
with a scientific record approaching that of many
prescription drugs. It is a prescription antidepressant in
Germany, covered by the national health-care system, and is
prescribed more frequently for depression than any synthetic
Saint John's wort is
also useful for its antiviral and antibacterial properties.
It also has tonic effects on nerves.
Interest in Saint
John's wort is ongoing regarding antiviral activity and the
potential to treat diseases including both human and feline
AIDS infections. While definitive proof is lacking, it may
be worthwhile to try Saint John's wort in pets with severe
viral infections (canine distemper, feline leukemia and
Applied locally, this
herb is useful to heal wounds.
In people, the current
recommendation is 300 mg three times daily of the 0.3%
hypericin standardized solution as a treatment for
depression. A few new products on the market are
standardized to hyperforin content (usually 3 to 5%) instead
of hypericin. These are taken at the same dosage.
In dogs, a dose of
250-300 mg twice daily for large dogs has been recommended
and proven useful clinically.
In people, research
suggests that ST Johnís wort is effective in
about 55% of cases. As with other antidepressants, the full
effect takes approximately 4 to 6 weeks to develop. Although
St. Johnís wort appears to be somewhat less powerful
than standard antidepressants, it rarely causes side
Use of Saint John's
wortmay potentiate anesthetics and other sedatives;
photosensitivity has been reported in people taking high
doses. The herb should not be taken with other drugs which
can inhibit MAO. In people, it is recommended to take the
herb with food to decrease gastrointestinal upset.
In people, the most
common are mild stomach discomfort allergic reactions
(mainly a rash,) lethargy, and restlessness.
involving very large doses for 26 weeks have not shown any
Do not combine St.
Johnís wort with prescription antidepressants except on the
specific advice of a veterinarian, especially drugs that
increase serotonin levels. Since some antidepressants, such
as Prozac, linger in the blood for quite some time, caution
is advised when switching from a drug to St Johnís
wort . The safest approach is to stop administering similar
medications and allow them to wash out of your pet's system
before starting St. Johnís wort Consult with your
veterinarian on how much time is necessary.
There has also
recently been an informal report of St Johnís wort lowering
blood levels of theophylline, an asthma medication, in
people. Preliminary investigation suggests that the
hypericin in st Johnís wort may increase the activity of a
liver enzyme called cytochrome P-450. Because this enzyme
can break down drugs, St . Johnís wort may cause the body to
speed the breakdown of various drugs (such as theophylline),
thereby decreasing their effectiveness.
John's wort (depression) may raise blood pressure,
cause agitation, drowsiness, and confusion in surgical
reports from the University of Colorado suggest that St.
Johnís wort may interfere with the action of the antitumor
drugs etoposide (VePesid), teniposide (Vumon), mitoxantrone
(Novantrone), and doxorubicin (Adriamycin).
Safety in young
children, pregnant or nursing women, or those with severe
liver or kidney disease has not been established; similar
precautions in pets is probably also warranted.