Denamarin vs. Milk Thistle: 2024 Comparison and Key Differences

Dogs and cats often experience compromised liver function as they age. Dogs and cats with liver problems exhibit the same symptoms, including vomiting, weight loss, soft or grey stools, or listlessness. Pets with advanced liver disease may have jaundice (yellow eyes, gums, or skin), convulsions, a swollen abdomen, or confusion.

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Some pets may show no symptoms, but show reduced liver function on a medical test.

Treatment for liver disease depends on the severity of the issue and its underlying cause. In chronic cases, surgery may be necessary. However, most cases can be treated with medication. The liver has a great healing capacity, so any problems can be successfully treated if caught early enough.

If tests show your pet has reduced liver function but hasn’t developed liver disease, you may use a supplement to treat her.

Natural supplements can be used to treat liver problems, diabetes, and irritable bowel syndrome in dogs and cats. Milk thistle (Silybum marianum) has been used as a liver tonic for animals and humans for thousands of years. Trusted sources have verified its usefulness.

A dog or cat diagnosed with liver disease should receive a treatment plan from a veterinarian. Talk to your vet about the best treatment for your pet. Chewables and tablets, such as Nutramax’s Denamarin, may be appropriate for your pet. Denamarin is prescribed for dogs and cats.

What to Look for in a Good Liver Treatment

A liver treatment should be easy for a dog or cat to take. Chewables are the best option because your dog will eat it like a treat, and most chewables are poultry or meat-flavored. Tablets should be administered to your pet on an empty stomach one hour before mealtime.

Natural liver treatments, like milk thistle, come in many easy to administer forms, including powders and liquid drops.

There are several ingredients to look for in liver treatments for dogs and cats. These ingredients include the following:

  • SAMe ( forms glutathione to support the liver through methylation)
  • Vitamin E (stops the liver from accumulating copper)
  • Vitamin B12 (aids digestion and food absorption)
  • Methionine ( an amino acid that detoxifies the liver and metabolizes fats)
  • Dimethylglycine (DMG) (an amino acid that rebuilds liver cells and removes toxins)
  • N-Acetyl-L-Cysteine (an amino acid that gets rid of liver toxins)
  • Curcumin/Turmeric Extract (antioxidant/anti-inflammatory)
  • Dandelion (prevents excess fat formation in the liver)

A liver medication or supplement should come from a trustworthy manufacturer and receive many good to excellent reviews from pet parents. You must also double-check information regarding dosage and weight. Most liver medications and supplements are dosed according to a dog’s weight, not his age.

Denamarin vs. Milk Thistle Similarities

Denamarin and milk thistle treat liver disease in dogs and cats. Both contain Silybin, a compound found naturally in milk thistle. Silybin is also referred to as Silybum or Silymarin. This natural compound has also been shown to improve pancreatic issues in rats and can improve damage to kidney cells.

Both substances offer more than one way to administer the treatment. You can give your dog chewable Denamarin, or tablets hidden in a bit of food. Milk thistle is available in drops, powders, a chewable tablet, or other forms.

Milk thistle and Denamarin work by fostering oxidative balance and eliminating toxins in the liver. Silybin has antioxidant and anti-inflammatory abilities. By reducing inflammation, Silybin makes the liver and your pet’s entire body healthier and better able to guard against free radicals and other toxins.

Both products help your pet build new liver cells to protect against toxins and inflammation. The Silybin in milk thistle and Denamarin increase levels of the antioxidant glutathione, which protects the liver from disease-causing toxins. The detoxifying effects can also promote brain and kidney health.

Denamarin and milk thistle are well-tolerated by dogs and cats. Both products have no side effects (or minor ones) if used according to directions. Both products are easily ordered online from various sources, including

Dogs and cats have no problem taking these products, provided you give them the right dose per your vet’s instructions. Milk thistle can be placed in food, and Denamarin tables can be hidden in a small bit of food.

The use of Silybin in the prescription medication Denamarin and the popularity of milk thistle shows that natural ingredients are now embraced by the veterinary field as well as human medicine.

Denamarin and milk thistle should not be administered to pregnant or nursing dogs or cats.

Denamarin vs. Milk Thistle Differences

Denamarin is a prescription medication. Milk thistle is a holistic treatment that you can buy online or from a pet store or health food store.

Milk thistle consists of three different chemicals that form Silymarin. This antioxidant compound binds toxins to improve your pet’s liver function. Milk thistle is 100 percent natural. Most milk thistle supplements contain 80 percent silymarin.

Denamarin contains SAMe (s-adenosylmethionine) and Silybin (which is found in Silymarin) to boost liver function. S-Adenosylmethionine helps liver function by forming glutathione and methylation.

The glutathione in SAMe prevents liver cells from dying early and helps form healthy liver cells. Glutathione regenerates damaged tissues in your pet’s livers so it can deal with the toxins. The Silybin in Denamarin stops toxins from putting stress on liver cells. The combination of SAMe and Silybin offers your pet more liver-protecting ingredients.

Denamarin is available in tablets and chewable versions. The tablet version is sold in three sizes-small for cats and small dogs that weigh up to 12 pounds, medium for dogs from 13 to 34 pounds, and large for dogs that weigh 35 pounds or more.

Denamarin is also sold in a chewable form for dogs. The dosage depends on your dog’s weight. According to Nutramax, the manufacturer, a dog up to six pounds should receive a quarter chew. A seven to a 15-pound dog should receive a half-chew, and a 16 to 30-pound dog should receive one chew.

There are six more weight and dosage categories, for dogs weighing more than 46 pounds. The heaviest dogs (over 105 pounds) should receive four chews. Follow your vet’s directions regarding how often to administer the medication.

Milk thistle products are available without a prescription. Still, your veterinarian may be able to prescribe liquid drops you put in your pet’s food or chewables. You’ll need to consult manufacturer directions for the recommended age when your pet can take milk thistle.

If you do decide to give your pet a milk thistle supplement, don’t give him anything new to eat or drink a week before introducing the supplement. Adding new food to the diet can make it hard to discern the cause of any new side effects.

Denamarin vs. Milk Thistle Pricing Comparison

Denamarin and milk thistle are available from and other online pet outlets. We’ve included the most recent prices from in this pricing comparison. Other online and brick and mortar outlets sell these products, and prices may vary depending on the source.


Nutramax Denamarin Tablets for Cats and Small Dogs up to 12 pounds cost $26 for a 30 count box and $25 for auto-ship Tablets for Medium Dogs from 13 to 34 pounds cost $37 and $35 for auto-ship. Denamarin Tablets for Large Dogs 35 pounds and over cost $63 and $60 for auto-ship.

A 30 count bottle of Denamarin chewables costs $39, $37 with auto-ship. A 75 count bottle costs $91, and it costs $81 with auto-ship.

Milk Thistle

There are many milk thistle brands and types, so you will find it easy to buy one that works for your pet and your budget.

Liver Support Bites from Zesty Paws cost $30 for a 90 day supply and $28 with auto-ship.

Liquid formula Pet Wellbeing Milk Thistle Liver Support Dog Supplement costs $35 for a two-ounce bottle and $33 for auto-ship. Four-ounce bottle costs $60 and $57 with auto-ship.

Herbsmith Powdered Milk Thistle Supplement for Dogs and Cats costs $23 for a 75-gram jar, $42 for a 150-gram jar, and $109 for a 500-gram jar.

Even though Denamarin costs more than milk thistle supplements, we feel it is the best value for your money. Since it is a prescription medication, Denamarin contains several ingredients to improve liver health instead of just one. A vet prescribes this product, so you can be sure your pet is receiving the right treatment.

Our Review of Denamarin vs. Milk Thistle

Denamarin is prescribed to improve liver function in cats and dogs. This drug doesn’t cure liver disease, but it does control it in mild to moderate cases. Most pets tolerate it well.

Side effects are rare and have only been observed in primates, not dogs or cats. High doses of SAMe have been shown to cause mild nausea and gastrointestinal discomfort. The SAMe in Denamarin may cause high-strung dogs to become more excited. This prescription medication won’t interact with other drugs or supplements.

You don’t need to have a prescription to buy milk thistle. Do your research before buying milk thistle, and read reviews from consumers and experts about various brands before deciding on a particular product.

Milk thistle is usually sold as two or four-ounce liquid herbal formulas. You add drops to your pet’s food according to manufacturer directions. You can also buy milk thistle as chicken or bacon-flavored bites, chewables, powdered supplements, or bone broth.

Many milk thistle supplements also contain other natural ingredients. Some of these ingredients may be harmful to your pet, even though milk thistle may be beneficial. Read ingredient lists carefully, and ask your veterinarian for advice if you’re unsure about product safety.

Denamarin gets our vote as the preferred liver treatment because it has a carefully monitored manufacturing and prescribing process. You know how much to give your pet and exactly what’s in it. Milk thistle is holistic and doesn’t contain any additional ingredients like Denamarin. Still, you can’t be sure of product quality, as it varies from brand to brand.

Liver Treatment FAQs

Is  prescription medication always better than over-the-counter treatments for liver disease?

Prescription medication is always preferable if your pet has been diagnosed with moderate to severe liver disease. Relying on herbal supplements alone may not improve your pet’s health and may even make it worse. Always talk to your vet before giving your dog or cat milk thistle or another supplement.

Can you use a supplement and prescription medication for liver treatment simultaneously?

You shouldn’t give your pet any supplement or medication, including milk thistle and Denamarin, without consulting your vet first. There may be interactions between medications and supplements.

Giving your pet a supplement and medication to treat liver problems or another condition may put too much of a particular ingredient in your dog’s system and cause side effects or worse.

What can I do to keep my pet’s liver healthy?

Don’t feed your dog or cat fatty foods or any difficult to digest food. If your dog or cat is prone to liver problems, feed him a low-protein-low-fat diet. Avoid overfeeding your pet and make sure he gets enough exercise. Follow your veterinarian’s advice about nutrition and medications.


Milk thistle and Denamarin both contain Silybin, a time-tested treatment for liver damage. Denamarin has another natural, well-tolerated ingredient called s-adenosylmethionine (SAMe). When combined with Silybin, SAMe gives your pet better protection against liver disease SAMe works to increase glutathione and shield your pet’s liver against toxins.

Silybin also protects liver cells against toxins. Using a product with two toxin-fighting ingredients makes more sense, especially if your dog has moderate to severe liver damage.

If you do choose milk thistle for your dog or cat, make sure each dose contains 70 to 80 percent Silymarin. (Silymarin is the active compound in Silybin). Any product with less than 70 percent Silymarin won’t give your pet the anti-toxin protection he needs.

Don’t try to diagnose your pet’s liver problem. Always ask a vet for his or her opinion before deciding on treatment options. Read customer and expert reviews of any medication or supplement brand as well before using a particular treatment plan.

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