How Milk Thistle For Dogs Protects The Liver

milk thistle for dogs

Dogs, like humans, have to deal with exposure to toxins on a daily basis. There are toxins in the foods we eat, the water we drink, and the air we breathe. We can’t escape them.

And, like us, your dog’s liver filters toxins from his blood. Because the liver works so hard to eliminate all of these toxic substances … it’s highly susceptible to serious damage.

But milk thistle for dogs can really help support the liver and protect it from damage.

First, let’s look at causes and signs of liver damage.

Causes Of Liver Damage In Dogs

Here are some factors in liver damage …

  • Viruses
  • Bacteria
  • Drugs
  • Toxins
  • Free radicals
  • Inflammation

Liver disease is more common in dogs than you might expect. Certain breeds of dogs are more prone to liver disease because of a genetic difficulty to excrete copper. Among them are Labrador retrievers, Dalmatians and Great Danes.

Signs Of Liver Damage Or Disease In Dogs

Watch your dog for …

  • Loss of appetite
  • Lethargy
  • Jaundice
  • Dark urine
  • Pale gums
  • Sudden unexplained weight loss

What Is Milk Thistle?

Milk thistle is a flower in the Aster family. It’s native to the Mediterranean regions of Europe, North Africa, and the Middle East.

Humans have used milk thistle for medicinal purposes for over 2000 years … especially its roots and seeds. Conventional medicine accepts milk thistle as one of the few herbs with medicinal value.

There are three important chemicals isolated from the milk thistle

  • Silychristine
  • Silydianin
  • Silybin

Together, these three substances are known as silymarin.

Humans usually use milk thistle as a liver tonic. And silymarin can help dogs and other pets with …

  • Liver or kidney damage
  • Hepatitis
  • Jaundice
  • Leptospirosis
  • Parvovirus recovery

Protect Your Dog’s Liver With Milk Thistle

Research shows milk thistle extract can help prevent and repair liver damage.

Milk Thistle As Antioxidant

Milk thistle is a powerful antioxidant. Antioxidants protect us from chemicals in our bodies called free radicals. Exposure to environmental toxins can increase free radicals in the body. And free radicals can do a lot of damage to our cells. This is called oxidative stress and can lead to early aging and chronic diseases like arthritis … or even cancer.

Milk thistle protects the liver against harmful oxidative stress. One study found that milk thistle’s antioxidant ability could relieve the toxicity as well as improve the effects of an atrial fibrillation drug in dogs.

Milk Thistle Supports Detox

Many over-the-counter drugs and prescription medications can hurt the liver … especially in large enough doses or for long periods of time.

Researchers have found that milk thistle can prevent or reduce medication-induced liver damage. If you’ve been giving your dog medication, milk thistle will help flush out the chemicals and toxins.

Milk thistle can also help the liver eliminate heavy metal toxicity. This means milk thistle can be a great addition after vaccinations that contain mercury (thimerosal) or aluminum (often, both). 

Milk Thistle For Allergies

To combat allergens, the body produces histamine. The liver plays a role in this process … it removes the histamine from the body. But if your dog’s liver is weakened, it’s unable to break down toxins.

If the liver’s clogged with toxins and histamines build up in the body, this can lead to more allergic reactions. According to Mark Richardson in his article The True Cause of Allergies – It’s In The Liver

“The liver has to process toxins and when it can’t do its job it stores them. If it stores them it also produces additional histamines to protect itself. If an allergen is present the brain sends a message; ‘Send out a few histamines! I think there’s an invader!!’ and the liver proceeds. It releases too many, and you have the allergic response – hives, asthma, sneezing, etc. Cleanse the liver and maybe … you’ll become allergy/asthma free.”

Other Uses For Milk Thistle

Here are some other things milk thistle can help with …

Kidney Disease
Silymarin has been shown to reduce drug-induced kidney toxicity that leads to kidney failure in dogs.

Pancreatitis is common in dogs. Milk thistle can help ease pancreatitis symptoms.

Milk thistle has been shown to relieve giardia infections in dogs.

When given milk thistle at least once per week … dogs who suffer from diabetes need less insulin than they otherwise would have.

Caution: Monitor your dog’s blood glucose carefully and check with your vet before reducing your dog’s insulin dose.

How To Use Milk Thistle

Milk thistle isn’t a preventative or “just in case” herb. It’s best used to cleanse the liver after exposure to toxins or as a remedy for liver damage.

Milk thistle stimulates the growth of new liver cells to replace those that are dead or dying. And it helps protect against toxins that could cause further damage.

Milk thistle has best results when used as needed. Herbalists Mary Wulff and Greg Tilford explain in Herbs for Pets: The Natural Way to Enhance your Pet’s Life.

“Despite much of the publicity that has been generated about this ‘wonder herb’. milk thistle should not be used as a daily food supplement. Milk thistle is a medicine that is best reserved for situations in which the liver is already under abnormal stress.”

That means milk thistle is best given for 3-6 weeks followed by a 1-3 week break.

Caution: Don’t give milk thistle to pregnant and lactating dogs.

You can find milk thistle in most health food stores, in capsule, tincture or powder forms.

Milk Thistle Dosage For Dogs

The usual recommended extract of milk thistle contains 70 to 80 percent silymarin. Each extract should have a label with the silymarin percentage.

For tincture, give a starting dose of 1/4 tsp per 20 lbs of body weight per day, split into 2 to 4 equal doses. If you use powder, give 2-5 mg per 1 lb of body weight, 2 to 3 times per day.


Kenneth Flora et al. Milk thistle (Silybum marianum) for the therapy of liver disease.
The American Journal of Gastroenterology, Volume 93, Issue 2, 1998.

Vereckei A, Zipes DP, Besch H Jr. Combined amiodarone and silymarin treatment, but not amiodarone alone, prevents sustained atrial flutter in dogs. J Cardiovasc Electrophysiol. 2003 Aug;14(8):861-7.

Gogulski M, Cieślak A, Grabska J, Ardois M, Pomorska-Mól M, Kołodziejski PA, Libera K, Strompfová V, Szumacher-Strabel M. Effects of silybin supplementation on nutrient digestibility, hematological parameters, liver function indices, and liver-specific mi-RNA concentration in dogs. BMC Vet Res. 2021 Jun 26;17(1):228.

ES Hacket et al. Milk Thistle and Its Derivative Compounds: A Review of Opportunities for Treatment of Liver Disease. Journal of Veterinary Internal Medicine, Vol. 27. Issue 1, January-February 2013

Varzi HN, Esmailzadeh S, Morovvati H, Avizeh R, Shahriari A, Givi ME. Effect of silymarin and vitamin E on gentamicin-induced nephrotoxicity in dogs. J Vet Pharmacol Ther. 2007 Oct;30(5):477-81.

Chon SK, Kim NS. Evaluation of silymarin in the treatment on asymptomatic Giardia infections in dogs. Parasitol Res. 2005 Dec;97(6):445-51. 

Seyed Sina Ravari et al. The effects of silymarin on type 2 diabetes mellitus: A systematic review and meta-analysis. Obesity Medicine, Volume 26, 2021

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