Milk Thistle for Dogs: Benefits and Uses

The milk thistle (Silybum marianum) from the daisy family is not only an important medicinal plant. The milk thistle grows to a height of 1.5 m and has large, dark green leaves with pointed thorns on edge. Their few reddish-purple flowers are relatively small about the plant size.

Liver disease

Milk thistle has been used for thousands of years in liver diseases and to support detoxification in animals and humans. But what can the medicinal plant do? And what is there to consider when buying milk thistle extracts for dogs?.

The seven main effects of milk thistle for Dogs 

As early as the late 1960s, researchers identified silybin as the most important active ingredient in milk thistle fruits (which look like seeds). Silybin and some similar molecules are summarized today under the term silymarin. Silymarin is:

  1. antioxidant
  2. anti-inflammatory (anti-inflammatory)
  3. bilious (choleretic)
  4. stimulates regeneration
  5. liver protection (hepatoprotective)
  6. anti-scar (antifibrotic)
  7. Immune strengthening (immunomodulatory)
  8. Silymarin is an antioxidant

Many liver diseases result in oxidative stress in the liver tissue. For example, this is used to ward off infectious agents in acute illnesses but can become independent. In chronic liver diseases, it can help to destroy more and more liver tissue. Milk thistle seed silymarin can neutralize free radicals and thus counteract oxidative stress. 

It can help protect essential cell structures such as DNA and the cell membrane from free radical damage. Silymarin is also able to inhibit enzymes involved in the formation of free radicals and promote the formation of protective molecules (eg, sirtuins). Last but not least, it activates the body’s antioxidant systems, such as superoxide dismutase.

1. Silymarin inhibits inflammation


Among other things, silymarin inhibits the inflammatory reaction’s most important ways, the activation of the so-called NF-kappaB transcription factor. This promotes the formation of inflammation-promoting enzymes and messenger substances, which can become a chronic liver disease problem.

2. Silymarin stimulates the flow of bile.

It ensures that more bile salts are pumped into the bile and thus promotes, for example, fat digestion and the excretion of toxins bound to bile salts.

3. Silymarin promotes the regeneration of the liver.

As early as the 1980s, it was shown that after partial removal of the liver, silymarin promotes the regeneration of the remaining part of the organ. To date, it is not completely clear how this works. Presumably, protein formation increased by silymarin helps to regenerate damaged liver cells and to create new ones. Milk thistle for dogs with Cushing’s disease is excellent.

4. Silymarin protects the liver tissue.

It suppresses the formation of cell-damaging cytokines and blocks the absorption of toxins (toxins) into the liver cells.

5. Silymarin protects the liver tissue

It suppresses the formation of cell-damaging cytokines and blocks the absorption of toxins (toxins) into the liver cells.

6. Silymarin inhibits scar formation.

Liver fibrosis, also known as shrink liver, is a feared complication of many liver diseases. Damaged liver tissue is replaced by scar tissue. But the more scar tissue is created in the liver, the worse it can do its job. Silymarin inhibits the formation of the cells that make up the scar tissue (myofibroblasts).

7. Silymarin is immunomodulatory

In autoimmune liver diseases, i.e., when the immune system attacks the liver itself, silymarin inhibits specific immune cells (T-lymphocytes).

In various studies, silymarin stimulated the innate and acquired immune systems, thus strengthening the immune system.

The importance of milk thistle extracts for liver diseases has been best researched so far, but there are other exciting uses. For example, dogs treated with milk thistle extract and an antibiotic with Giardia infection showed fewer side effects of the antibiotic treatment. 

In diabetic dogs, silymarin reduces insulin resistance. Thanks to its antioxidant and cell-protecting properties, silymarin is also being intensively researched in connection with neurodegenerative diseases such as Parkinson’s and Alzheimer’s. 

How does milk thistle help dogs with liver disease?

Many animal nutrition experts recommend milk thistle extracts as part of special liver diets. Above all, they rely on the antioxidant and anti-inflammatory properties of milk thistle and have had good experiences in practice with their patients. Unfortunately, there are too few clinical milk thistle studies for our pets to make specific statements about certain liver diseases in dogs. 

So far, much has only been researched on cell cultures, laboratory animals, and in human patients, with different milk thistle extracts in different dosages. Although the effects of silymarin described above were also evident in the other species, it is only possible to a limited extent to transfer the results to animals with liver disease. 

What to look for when buying milk thistle extracts

Milk thistle extracts are of very different quality. The body poorly absorbs silymarin, so it has a low bioavailability. If you feed pure milk thistle powder (with 1.5 to 3% silymarin), there is usually no detectable silymarin in the blood. With milk thistle extracts that contain 70 to 80% silymarin, there is little silymarin in the blood, but significantly more in the bile, since silymarin is enriched there. 

Thanks to intensive research, it is now possible to improve the absorption of silymarin many times over, for example, by coupling it to lecithin. For some of these extracts with higher bioavailability, studies already exist that confirm adequate intake even in dogs.

If you buy a product with milk thistle extract, it is best to choose an excerpt whose bioavailability has explicitly been improved or pay attention to a standardized high silymarin content of approx. 80%. In general, the higher the milk thistle is mentioned in the list of ingredients, the more it is included. But since you cannot compare pure milk thistle powder and an extract with increased bioavailability, this hardly helps you assess the quality. If only milk thistle extract is declared without further details, it is best to ask the manufacturer in more fact.

We usually recommend choosing a dietary supplement for sick liver animals if you are looking for a milk thistle product. These meet specific legal requirements for their composition (eg, high content of essential fatty acids) and may bear the note “To support liver function in chronic liver failure.”

If you want to buy milk thistle for your dog with liver disease, it makes sense to choose a dietary supplement that supports liver metabolism with omega-3 fatty acids.

How much milk thistle should I give to my dog?

Dosage of milk thistle for dogs. Milk thistle for dogs dosage.

How much milk thistle for dogs. Experts recommend a dose of 20 to 50 mg per kg body weight and day. With milk thistle extracts with a targeted increase in bioavailability, a significantly lower amount may be sufficient. Since the milk thistle products are so different, the products’ dose cannot be compared with one another using the list of ingredients. In turn, asking here only helps if you want to know precisely.

Milk thistle oil is made from the elongated seeds of milk thistle. The shell of the seeds is tough to unlock by mammals. Infusion preparation also has little benefit for the liver, since the substance silymarin is not water-soluble.

  • Therefore, give your dog extracts of the plant, i.e., milk thistle oil – not the seeds. You can add this to the feed.
  • Therapy should be accompanied by diuretic herbs so that water-soluble substances can be excreted.
  • Older animals, in particular, should get milk thistle oil, because their metabolism is often disturbed. Obese animals or animals with skin and coat problems also benefit from this. 
  • Milk thistle oil supports the bile flow.

Medical application

The active ingredient complex Silymarin has a liver-protecting, liver-strengthening, detoxifying effect and stimulates bile flow and circulation.

In evidence-based medicine, liver poisoning (caused, for example, by eating tuber agarics) is treated with silibinin, which is obtained from the fruits of the thistle. Sylimarin changes the structure of the outer cell membrane of the hepatocytes in such a way that liver toxins cannot penetrate into the cell interior. Sylimarin stimulates the activity of nucleolar polymerase A, which leads to increased ribosomal protein synthesis. This increases the regeneration of the liver.

Other active ingredients in the plant are: bitter substances, biogenic amines, tannins, dyes, to a small extent also essential oils, unknown harsh substances and resins.
Clinical studies have also shown success in preventing skin and prostate cancer, which is due to the antioxidant effect.

Other applications: biliary disorders, gastrointestinal disorders, migraines, motion sickness, possibly trigeminal neuralgia, varicose veins, portal vein congestion.
Milk thistle fruits are also being used increasingly in the field of livestock feeding, with the liver therapy effect being the main focus.


Milk thistle supports liver function in many ways and is often recommended by veterinarians. Nevertheless, there is still a need for research in dogs with liver disease. Dietary supplements that also contain milk thistle are most suitable for liver-sick animals.

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