Milk thistle, otherwise known as Silybum marianum, is a prickly flowery plant from which the popular milk thistle supplements for humans are made. But today we are going to go over milk thistle for dogs and the potential uses and benefits could be.

Unlike many other “natural” remedies, milk thistle actually has quite a bit of science behind its benefits with humans, but not yet enough with dogs for vets to confidently recommend it (1).

These remedies are common in all-natural and homeopathic circles and are used both with humans and dogs.

What is Milk Thistle?

What is Milk ThistleMilk thistle extract is derived from the seeds of the milk thistle plant.

In fact, the plant got its name from the milky sap that comes out of the leaves when they are broken as well as the splotchy white spots on the leaves.

The plant is native to Europe but can also be found in Canada, the United States, South America, and the Middle East.

It's been used for medicinal purposes for over 2,000 years. Milk thistle was found to be safe for consumption by both humans and dogs (2, 3).

However, because it is an herb, there are no regulations or standard dosing practices.

There are three chemicals found in milk thistle: silychristin, silydianin, and silybin. The mixture of these three chemicals is called Silybum.

The active ingredient in milk thistle is called silymarin, which constitutes about 65-80% of the milk thistle extract (4).

Milk Thistle for Dogs and Its Known Uses

Milk thistle is currently tested to be used to help with liver disease in dogs primarily.

In addition, it may sometimes be recommended by some vets to support a dog’s immune system, as an aid in the recovery of several other ailments, as an anti-inflammatory, good source of antioxidants, for treatment of insulin-resistant diabetes, and “detoxifying” the body.

Most of these uses of milk thistle for dogs are based on what has been observed in human trials and not those with canines (1, 4).

A list of ailments that may potentially be helped through the use of milk thistle:

  • Liver disease and liver damage
  • Kidney disease and kidney damage
  • Mushroom poisoning
  • Diabetes and insulin resistance
  • Cancer and tumors
  • Hepatitis
  • Seasonal allergies

Milk thistle can be easily administered to a dog in the form of a tablet or through liquid drops. Many dog supplement brands offer milk thistle in a pill form that tastes like a dog treat for easy administration.

When used in liquid form, drops can be dissolved in your dog’s water or dropped directly onto their food.

It is a relatively inexpensive, all-natural herb that can be purchased online or in stores without a prescription.

Over the past several years, the use of milk thistle has become more accepted in the veterinary community as they saw its benefits with people.

Milk thistle is not suggested to be used as preventative medicine or given to dogs long-term. It should only be used to help treat the above ailments after a proper diagnosis has been made by a vet, and it should only be used on a short-term basis.

See below to understand how milk thistle for dogs is used to potentially help with the above ailments.

5 Potential Benefits of Milk Thistle for Dogs

Milk Thistle for Dogs: 5 Potential Benefits of

Studies found milk thistle to be safe for both humans and dogs, but when it comes to its proven benefits, there's still not enough scientific evidence with dogs.

However, it has been widely researched in human trials, and studies found several benefits of milk thistle. Below are some benefits of milk thistle for dogs based on what we've seen in people.

1. Liver Disease, Function, and Repair

Milk thistle helps patients with liver disease. When used as a complementary therapy supplement, it can repair liver damage through regenerating the liver (5). It also detoxifies the liver and then protects it from toxins.

Milk thistle extract supports healthy liver function by lowering elevated liver enzymes (6).

It is believed that because of its anti-inflammatory properties and the benefit of repairing the liver, milk thistle may also benefit dogs with inflammatory bowel disease (IBD) too.

2. Diabetes and Kidney Function

Milk thistle may be used as a natural way to help manage diabetes in dogs.

In human trials, one study found that it works similar to many chemical medications for diabetes as it decreases blood sugar and improves insulin sensitivity, so it may work with dogs who are insulin resistant diabetics by reducing resistance a dog has to insulin (7, 8).

The supplement also helps repair kidney damage as a result of diabetes and generally assists with kidney function (7).

3. Cancer and Tumors

Some veterinarians that are open to the use of natural supplements suggest using milk thistle along with (not instead of) medicinal treatment to help dogs with cancer, and there's some research behind its uses in such cases.

For example, milk thistle was found to decrease blood flow to tumors and slow down the growth of cancerous cells (9, 10, 11).

Studies with mice discovered that it protects internal organs during radiation and/or chemotherapy treatments and reduces other side effects from these treatments (12, 13).

In addition, milk thistle even makes such cancer treatments more effective (10, 11).

It is important to note that milk thistle is not suggested to be a replacement for radiation or chemotherapy treatments.

4. Mushroom Poisoning

Some mushrooms can be toxic to dogs if ingested. The death cap mushroom, for example, is as deadly to dogs as it is to humans because it contains a toxin known as amatoxin.

Studies found that one of the main chemicals in milk thistle, silibinin, is effective at treating mushroom poisoning (14, 15).

5. Other Potential Benefits

Dementia. Scientists found that compounds in milk thistle provide protection to the brain, and it can serve as a neuroprotective substance to help with brain function decline and conditions like dementia (16, 17, 18).

Allergies. Antioxidants and the anti-inflammatory properties of milk thistle for dogs may potentially help decrease their seasonal allergies and accompanying symptoms.

Bones. Studies with mice have shown that milk thistle protects bones and prevents bone loss, helps with bone mineralization, and delaying bone-related diseases (19, 20).

Side Effects of Giving Milk Thistle to Dogs

Milk thistle has been extensively studied in humans and has very few known side effects.

However, when it comes to dogs, while it was found to be safe to use it with canines, there's not enough research to claim we know of all potential side effects of milk thistle for dogs.

In anecdotal evidence and claims from veterinarians and pet owners, most dogs tolerate the herb well.

The most common side effects noted have been gastrointestinal distress, mild digestive upsets, and loose stools.

Most dogs do not experience these side effects when the recommended dosage is followed, and if they do, the side effects do not last very long.

As a dog adjusts to the ingestion of milk thistle, these symptoms are believed to reduce over time as the pet's body gets used to the herbs.

Milk thistle is not recommended for use in pregnant or nursing dogs.

Suggested Milk Thistle Dosage for Dogs

While a prescription is not needed to purchase milk thistle, it is recommended for you to speak to your veterinarian prior to administering milk thistle to dogs so that a proper dosage can be established.

As a guideline (which is often included on milk thistle for dogs supplements), pets should be given ¼ of a teaspoon for every 20 pounds of their weight.

For example, one teaspoon should be given to a dog weighing 80 pounds.

Best Milk Thistle for Dogs Supplements

There are several brands of milk thistle for dogs supplements that vets and pet owners found to be effective and not produce any side effects.

However, because there are no regulations for such nutraceuticals, it's highly recommended that you discuss this with your veterinarian prior to purchasing.

Milk Thistle For Dogs: In Summary

Milk thistle is an herb that is derived from the seeds of the milk thistle plant. There's not enough evidence to make confident claims about milk thistle for dogs.

It has many uses, and human trials found that it can be beneficial in treating liver disease, kidney disease, cancer, mushroom poisoning, allergies, diabetes, and more.

The extract has anti-inflammatory properties and is a great antioxidant.

However, milk thistle for nursing dogs is not recommended long term, nor in pregnant dogs.

There have been very few observed side effects of milk thistle, but those that may happen to include gastrointestinal distress, mild digestive upset, and loose stools.

Milk thistle can be purchased without a prescription, but it's strongly advised to consult your veterinarian for dosage suggestions.

It can be administered to your pet through tablet form or through liquid drops.


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  2. Filburn CR, et al. Bioavailability of a silybin-phosphatidylcholine complex in dogs. J Vet Pharmacol Ther. 2007 Apr;30(2):132-8.
  3. Varzi HN, et al. Effect of silymarin and vitamin E on gentamicin-induced nephrotoxicity in dogs. J Vet Pharmacol Ther. 2007 Oct;30(5):477-81.
  4. Abenavoli L, et al. Milk thistle in liver diseases: past, present, future. Phytother Res. 2010 Oct;24(10):1423-32. doi: 10.1002/ptr.3207.
  5. Federico A, et al. Silymarin/Silybin and Chronic Liver Disease: A Marriage of Many Years. Molecules. 2017 Jan 24;22(2). pii: E191. doi: 10.3390/molecules22020191.
  6. Polachi N, et al. Modulatory effects of silibinin in various cell signaling pathways against liver disorders and cancer – A comprehensive review. Eur J Med Chem. 2016 Nov 10;123:577-595. doi: 10.1016/j.ejmech.2016.07.070. Epub 2016 Jul 29.
  7. Kazazis CE, et al. The therapeutic potential of milk thistle in diabetes. Rev Diabet Stud. 2014 Summer;11(2):167-74. doi: 10.1900/RDS.2014.11.167. Epub 2014 Aug 10.
  8. Voroneanu L, et al. Silymarin in Type 2 Diabetes Mellitus: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. J Diabetes Res. 2016;2016:5147468. doi: 10.1155/2016/5147468. Epub 2016 Jun 1.
  9. Polachi N, et al. Modulatory effects of silibinin in various cell signaling pathways against liver disorders and cancer – A comprehensive review. Eur J Med Chem. 2016 Nov 10;123:577-595. doi: 10.1016/j.ejmech.2016.07.070. Epub 2016 Jul 29.
  10. Imai-Sumida M, et al. Silibinin suppresses bladder cancer through down-regulation of actin cytoskeleton and PI3K/Akt signaling pathways. Oncotarget. 2017 Sep 8;8(54):92032-92042. doi: 10.18632/oncotarget.20734. eCollection 2017 Nov 3.
  11. Bosch-Barrera J, et al. Silibinin and STAT3: A natural way of targeting transcription factors for cancer therapy. Cancer Treat Rev. 2015 Jun;41(6):540-6. doi: 10.1016/j.ctrv.2015.04.008. Epub 2015 Apr 27.
  12. Shukla SK, et al. Silibinin-mediated metabolic reprogramming attenuates pancreatic cancer-induced cachexia and tumor growth. Oncotarget. 2015 Dec 1;6(38):41146-61. doi: 10.18632/oncotarget.5843.
  13. Bosch-Barrera J, et al. Targeting STAT3 with silibinin to improve cancer therapeutics. Cancer Treat Rev. 2017 Jul;58:61-69. doi: 10.1016/j.ctrv.2017.06.003. Epub 2017 Jun 23.
  14. Mengs U, et al. Legalon® SIL: the antidote of choice in patients with acute hepatotoxicity from amatoxin poisoning. Curr Pharm Biotechnol. 2012 Aug;13(10):1964-70.
  15. Ward J, et al. Amatoxin poisoning: case reports and review of current therapies. J Emerg Med. 2013 Jan;44(1):116-21. doi: 10.1016/j.jemermed.2012.02.020. Epub 2012 May 1.
  16. Devi KP, et al. A Mini Review on the Chemistry and Neuroprotective Effects of Silymarin. Curr Drug Targets. 2017;18(13):1529-1536. doi: 10.2174/1389450117666161227125121.
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  19. Kim JL, et al. Antiosteoclastic activity of milk thistle extract after ovariectomy to suppress estrogen deficiency-induced osteoporosis. Biomed Res Int. 2013;2013:919374. doi: 10.1155/2013/919374. Epub 2013 May 28.
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Milk Thistle for Dogs - Its Uses, Benefits and Side Effects

Mary has a Bachelor of Science in Biology and Neuroscience, and has been specializing in animal science writing for over ten years. She's very experienced in scientific reports, data analysis and science-based research, and obsessed with accurate information.