Penicillamine for Dogs

Molly Price, DVM
By Molly Price, DVM on Nov. 13, 2023
dog on table while vet looks at him

In This Article

How It Works

What Is Penicillamine?

Penicillamine is a medication prescribed by veterinarians for dogs with copper storage hepatopathy, a condition caused by an abnormal buildup of copper in the liver, which can lead to damage and scarring of the liver.

Copper storage hepatopathy is often caused by a genetic disorder, but it can also be caused by other liver conditions. Penicillamine helps remove excess copper from the liver, and sometimes, may also be used to remove excess lead or mercury from the body in cases of lead poisoning or mercury poisoning.

Penicillamine is FDA-approved for human use under the brand names Cuprimine® and as generic penicillamine. Penicillamine is currently not FDA-approved as a veterinary medication. However, it is readily utilized in the veterinary field, and veterinarians can legally prescribe certain human drugs in animals in certain circumstances. This is called extra-label or off-label use because this use isn’t described on the drug label.

In certain circumstances, your vet may recommend a compounded formulation of penicillamine. Compounded medications are prescribed if there’s a specific reason your pet’s health can’t be managed by an FDA-approved drug, such as if your pet has trouble taking pills in capsule form, the dosage strength is not commercially available, or the pet is allergic to an ingredient in the FDA-approved medication.

Compounded medications are not FDA-approved. They are created by either a veterinarian or a licensed pharmacist on an individual basis to best suit a patient’s particular needs. You can learn more about compounded medications here.

Penicillamine Considerations

Penicillamine should not be used in pets with certain medical conditions, such as in pets with kidney disease, if there is lead in their gastrointestinal tract, or if they are hypersensitive to penicillin.

Giving penicillamine with certain medications can result in health risks to your pet, so it is important to discuss your pet’s medications, including vitamins and supplements, and medical conditions with your veterinarian.

Penicillamine may cause birth defects and should be used with caution in pregnant or nursing pets.

Penicillamine can cause low levels of certain essential vitamins and minerals such as zinc, iron, copper, calcium, and pyridoxine (vitamin B6), so your vet may recommend adding a supplement to their diet during treatment.

During treatment, your veterinarian will perform specific blood and urine monitoring to assess how well penicillamine is working for your pet, and evaluate their immune system function as well as the effects of the drug on the liver and kidneys.

Additional monitoring may be recommended depending on your pet's individual needs, other medications they may be on, or the issue that initially caused your pet to be placed on this medication.

How Penicillamine Works

Penicillamine is classified as a chelating agent. It binds to excess copper in the liver to form stable water-soluble complexes that the kidneys can excrete into the urine, thereby decreasing copper levels in the body.

Penicillamine can also chelate a variety of other metals such as lead, iron, and mercury, so it may be used for treatment of lead poisoning and mercury poisoning. Penicillamine is a breakdown product of penicillin, but, unlike penicillin, it has no antibiotic properties.

Missed a Dose?

Speak with your veterinarian about what to do if you forget to give a dose of penicillamine. Generally, they may instruct you to give it at least 30 minutes before your pet’s next meal, or if it is almost time for your pet’s next dose, to skip the missed dose and resume your normal dosing schedule. Do not give extra or double doses.

Penicillamine Directions

Follow the directions on the drug label or as provided by your veterinarian.

Penicillamine is best absorbed if given on an empty stomach at least 30 minutes before a meal. Food can significantly lower the amount of medication absorbed into the body.

If your pet develops a decreased appetite, nausea, or vomiting on this medication, your vet may suggest giving a long-acting anti-nausea medication such as Cerenia® (maropitant) to be given 1 hour before your pet’s dose. Other suggestions may also include dividing your pet’s dose into smaller doses per day, temporarily reducing your pet’s dose then gradually increasing it when your pet is feeling better, or giving with a very small amount of food.

Penicillamine Possible Side Effects

Side effects of penicillamine may include:

  • Gastrointestinal upset: decreased appetite, nausea, and vomiting

  • Fever

  • Swollen lymph nodes

  • Skin rash, hives, and itching (skin hypersensitivity reaction)

  • Kidney issues

Human Side Effects

Penicillamine is also a prescription medication for humans, frequently with dosages different from those prescribed for your pet by a veterinarian. Due to possible side effects, humans should never use medicine dispensed for their pets and pets should not be given any medicine dispensed for a human’s use.

Call Your Vet If:

  • Severe side effects are seen (see above)

  • You see or suspect an overdose

  • You have additional questions or concerns about the use of penicillamine

Penicillamine Overdose Information

Studies have not been performed to evaluate the toxicity of penicillamine in animals. Toxicity can occur in pets taking small dosages or in pets taking higher dosages for long periods of time.

If you suspect an overdose, immediately contact your veterinarian, seek emergency veterinary care, or call an animal poison control center. Consultation fees often apply.

Pet Poison Helpline (855) 764-7661

ASPCA Animal Poison Control (888) 426-4435

Penicillamine Storage

Penicillamine should be stored at controlled temperatures from 68 to 77 F.

Keep the container tightly closed in order to protect its contents from moisture and light.

Always confirm storage requirements by reading the prescription label.

Compounded medications should be stored according to the compounding pharmacy’s label.

Keep out of reach of children and pets.

Penicillamine for Dogs FAQs

What is penicillamine used for in dogs?

Penicillamine is used off-label in veterinary medicine to treat copper storage hepatopathy and metal (lead and mercury) toxicity in dogs.

How much does penicillamine cost for dogs?

The cost for penicillamine can vary depending on your dog’s weight and the dosage and frequency schedule your veterinarian recommends.

How long does it take for penicillamine to work in dogs?

It may require weeks to months of treatment for penicillamine to work in dogs.

No vet writer or qualified reviewer has received any compensation from the manufacturer of the medication as part of creating this article. All content contained in this article is sourced from public sources or the manufacturer.

Featured Image: AzmanL/E+ via Getty Images


Fieten H, Dirksen K, van den Ingh T, et al. D-penicillamine treatment of copper-associated hepatitis in Labrador retrievers. Veterinary Journal. 2013;196(3):522-527.


Molly Price, DVM


Molly Price, DVM


Dr. Molly Price has practiced small animal medicine for over 20 years and is a graduate of Texas A&M College of Veterinary Medicine. She...

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