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Frequently asked questions

General Vetsulin® (porcine insulin zinc suspension) questions

  1. What is Vetsulin?
  2. Is this a brand new insulin?
  3. Is Vetsulin made here in the US?
  4. Can Vetsulin be kept at room temperature? Is it okay if Vetsulin is frozen?
  5. What type of insulin is Vetsulin?
  6. Can Vetsulin be diluted?
  7. Can I use 100 IU syringes with Vetsulin?
  8. How does Vetsulin differ from human insulin products?
  9. For owners whose dogs or cats have been treated with human insulin, what differences or benefits could they see if their pets were treated with Vetsulin?
  10. What issues might a dog or cat encounter when switching from human insulin to Vetsulin?
  11. How is Vetsulin distributed?
  12. How long can Vetsulin be used?

Vetsulin treatment in dogs

  1. How does Vetsulin work in dogs?
  2. What results typically can be expected from Vetsulin therapy in dogs?
  3. How often does Vetsulin need to be administered in dogs?
  4. Can Vetsulin really be used only once daily in dogs?
  5. How does Vetsulin differ from the human insulin products traditionally prescribed for diabetic dogs?
  6. How many dogs currently have diabetes?

Vetsulin treatment in cats

  1. How does Vetsulin work in cats?
  2. What results typically can be expected from Vetsulin therapy in cats?
  3. How often does Vetsulin need to be administered in cats?
  4. How many cats currently have diabetes?

About VetPen®

  1. What makes VetPen unique?
  2. Is VetPen difficult to use?
  3. Is VetPen more accurate than using an insulin syringe?
  4. Can VetPen be used with different insulins?

Using VetPen

  1. How does selecting a dose with VetPen differ from drawing up a dose with a syringe?
  2. How do I know when the injection is complete?
  3. Why does the VetPen need to be tested before each injection?
  4. What should the insulin cartridge look like after mixing and priming?
  5. Is VetPen reusable?
  6. What type of needle is used with VetPen?
  7. Can VetPen needles be reused?
  8. Does VetPen need to be kept refrigerated when it contains an insulin cartridge?
  9. What is the proper care of VetPen?

Troubleshooting VetPen

When experiencing any issues using VetPen, the first step should always be to confirm that air was properly removed from the cartridge through priming. Air bubbles in the cartridge can create multiple issues that result in the pet receiving too much or too little insulin.

  1. What if insulin drips actively from the needle after injection?
  2. What if the dose selector does not return to the start line after testing VetPen?
  3. What if there is not enough insulin in the cartridge to complete an injection?
  4. What if a dose too large for the pet is selected?
  5. What if no insulin drips actively or squirts from the needle after priming or preparing for use?

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Answers to general Vetsulin questions

What is Vetsulin?

The first and only insulin approved by the US Food and Drug Administration for treating both canine and feline diabetes mellitus. Vetsulin® (porcine insulin zinc suspension) is produced by Merck Animal Health and is available only by prescription.

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Is this a brand new insulin?

No, Vetsulin is registered in over 30 other countries as Caninsulin®. It was first registered in Australia in 1990, so there is a history of more than 20 years of safety and efficacy with this product.

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Is Vetsulin made here in the US?

No, Vetsulin/Caninsulin are manufactured by Merck Animal Health in Germany.

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Can Vetsulin be kept at room temperature? Is it okay if Vetsulin is frozen?

Yes, Vetsulin may be kept at room temperature—no higher than 77°F at 60% relative humidity—between dosing administrations. Vetsulin should not be frozen.

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What type of insulin is Vetsulin?

Vetsulin is an intermediate-acting, lente insulin containing 40 IU per mL of highly purified porcine insulin. As a lente insulin, Vetsulin is an aqueous suspension containing 35% amorphous and 65% crystalline zinc crystals in a neutral buffer of pH 7.35.

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Can Vetsulin be diluted?

No. Vetsulin is a mixture of amorphous (soluble) insulin and crystalline insulin. The crystalline part is relatively insoluble, which is why the insulin activity lasts more than a few hours. Vetsulin has a balance between the amorphous and crystalline parts. If Vetsulin is diluted, the balance between amorphous and crystalline parts is no longer 35% and 65%, relatively speaking. The amount of soluble insulin is increased by the aqueous diluent used. This results in an alteration of the pharmacokinetics of Vetsulin. With a larger aqueous fraction and smaller crystalline fraction, there would be a decrease in the crystalline portion responsible for the second peak of insulin activity.

In addition, the stability of the suspension is unknown if Vetsulin is diluted. The Vetsulin suspension is optimized to maintain the crystalline portion as a salt. If the water content is increased as with dilution, the solution looks for a new balance, ie, it is not stable and the dissolved fraction increases with time.

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Can I use 100 IU syringes with Vetsulin?

No, use of a syringe other than a U-40 syringe will result in incorrect dosing. Using a U-100 syringe with Vetsulin would result in an animal receiving 2½ times less insulin than required. Human insulins are formulated at a concentration of 100 IU/mL. If clients use a U-40 syringe with a 100 IU insulin preparation, they would be injecting 2½ times the amount of insulin necessary, which could result in fatal hypoglycemia.

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How does Vetsulin differ from human insulin products?

Vetsulin porcine insulin has the same amino acid sequence as natural canine insulin, whereas the commonly prescribed biosynthetic human insulin has a different amino acid sequence. The similar structure may provide more effective regulation of blood glucose and decreases the risk of anti-insulin antibody development in dogs. Unlike the dog, anti-insulin antibodies do not appear to be a problem in cats.

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For owners whose dogs or cats have been treated with human insulin, what differences or benefits could they see if their pets were treated with Vetsulin?

Vetsulin facilitates a more optimal treatment protocol than current human insulin products.

  • Where biosynthetic human insulin is only available in 100 IU/mL concentrations, Vetsulin has a 40 IU/mL concentration allowing for more accurate dosing of small animals and reducing the risk of under- or overdosing.
  • Vetsulin is administered with U-40 syringes or VetPen®, making it easier for the client to read and deliver the dose.
  • The duration of activity may be longer.

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What issues might a dog or cat encounter when switching from human insulin to Vetsulin?

Caution should be exercised when changing from one insulin product to another. Any change in insulin should be made cautiously and only under a veterinarian’s supervision. Changes in insulin strength, manufacturer, type, species (animal, human), or method of manufacture (rDNA versus animal-source insulin) may result in the need for a change in dosage.

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How is Vetsulin distributed?

To order Vetsulin, contact your Merck Animal Health sales or distributor representative. For more information, or for technical support, call 800-224-5318 weekdays between 8:30 am and 5 pm EST.

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How long can Vetsulin be used?

It is recommended that Vetsulin vials and cartridges in use be replaced 42 days after they are first punctured.


Answers to questions about Vetsulin treatment in dogs

How does Vetsulin work in dogs?

A lente (intermediate-acting) form of insulin, Vetsulin contains 35% amorphous insulin for rapid onset of activity, usually peaking 4 hours after injection and lasting 8 hours. The remaining 65% of the formula is crystalline insulin which is absorbed more slowly and peaks around 11 hours after administration. The Vetsulin formula allows for a more continuous utilization of glucose to support the body’s basic functions. Vetsulin is administered subcutaneously once daily initially, although two-thirds of dogs require twice-daily administration for effective diabetes management.

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What results typically can be expected from Vetsulin therapy in dogs?

Diabetic dogs in clinical trials responded to porcine insulin in the following ways:

  • Substantially reduced mean 12-hour blood glucose concentration and mean blood glucose nadir post treatment, compared to pre-treatment levels.
  • Reduced incidence of polyuria, polydipsia, and ketonuria in most dogs.
  • Adequate blood glucose control in most dogs with less than one-third having hypoglycemic episodes.

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How often does Vetsulin need to be administered in dogs?

Initially, the dose should be given once daily concurrently with or right after a meal. The veterinarian should reevaluate the dog at appropriate intervals and adjust the dose in 10% increments based on clinical signs, urinalysis results, and glucose curve values until adequate glycemic control has been attained. Twice-daily therapy should be initiated if the duration of insulin action is determined to be inadequate.

If twice-daily treatment is initiated, each of the two doses should be 25% less than the once-daily dose required to attain an acceptable nadir.

The impact on blood glucose peaks may last from 14 to 24 hours, and approximately one-third of diabetic dogs can achieve successful diabetes management with a single dose of Vetsulin per day. The treating veterinarian would need to determine the frequency of a patient’s dose.

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Can Vetsulin really be used only once daily in dogs?

Clinical studies have demonstrated that approximately one-third of diabetic dogs can be maintained adequately on once-daily doses of Vetsulin. The other two-thirds of dogs will require twice-daily administration of Vetsulin.

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How does Vetsulin differ from the human insulin products traditionally prescribed for diabetic dogs?

Vetsulin has the same amino acid sequence as natural canine insulin, whereas the commonly prescribed biosynthetic human insulin has a different amino acid sequence. The similar structure may provide more effective regulation of blood glucose and decreases the risk of anti-insulin antibody development.

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How many dogs currently have diabetes?

It is estimated that up to 1 in 100 dogs suffers from the signs of diabetes mellitus.10

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Answers to questions about Vetsulin treatment in cats

How does Vetsulin work in cats?

Vetsulin is a lente (intermediate-acting) form of insulin that contains 35% amorphous insulin for rapid onset of activity. In cats, the peak activity following subcutaneous administration of Vetsulin occurs between 1.5 and 8 hours (with an average of about 4 hours1), and the duration of activity varies between 8 and 12 hours. This is why, in cats, Vetsulin is initially administered twice daily rather than once daily.

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What results typically can be expected from Vetsulin therapy in cats?

In the Vetsulin feline efficacy study, cats were initially started on 1 to 2 IU of Vetsulin per injection twice daily. Glycemic control was evaluated based on blood glucose curves and clinical signs. Adjustment of the Vetsulin dose was made according to average blood glucose curve levels, blood glucose curve nadirs, and clinical improvement. At the end of the study, the mean Vetsulin dose was 3.3 IU per injection twice daily with a maximum dose of 8 IU per injection twice daily. Five percent of the cats in the study went into diabetic remission.

Test cats demonstrated significantly lower blood glucose levels and a reduction in hyperglycemic clinical signs compared with pretreatment levels.

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How often does Vetsulin need to be administered in cats?

In cats, the initial recommended dose is 1 to 2 IU per injection, and the injections should be given twice daily at 12-hour intervals. So, unlike in the canine where initial dosing is based on body weight, dosing of Vetsulin in the feline is based on a per animal basis. The duration of activity of Vetsulin in the cat is shorter than in the dog, ranging between 8 to 12 hours. Peak activity level occurs between 1.5 to 8 (average of about 4) hours in the cat.

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How many cats currently have diabetes?

Estimates of the incidence of diabetes mellitus in cats ranges from 1 in 50 to 1 in 500, depending on the source.9

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About VetPen

What makes VetPen unique?

While insulin pens have been commonly used in the management of human diabetes for some time, VetPen is the first such device designed exclusively for use in diabetic cats and dogs.

Using the same technology found in human insulin pens, VetPen:

  • Is more convenient and easier to use than insulin vials and syringes
  • Delivers an accurate dose consistently over time, with less chance of error
  • Provides a better fit to pet owners’ lifestyles—takes fewer steps to prepare doses once primed (air removed from cartridge) and can be used anywhere

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Is VetPen difficult to use?

VetPen is ergonomically designed for easy handling and dosing. Additional adaptors are provided to further assist pet owners with visual or manual dexterity issues.

In a 3-week study, close to 97% of pet owners reported that VetPen was easy to use overall.3 And more than 97% reported being able to learn how to use VetPen.12,13

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Is VetPen more accurate than using an insulin syringe?

Yes. In a laboratory study, VetPen was shown to be consistently more accurate than syringes for low doses. Even when drawn up by trained lab technicians, study results showed that U-40 syringes delivered at least 20%-25% more insulin than needed for a 1-unit dose.11 Unlike syringes, VetPen provides a precise and accurate dose every time, without relying on the user to draw up an accurate dose.

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Can VetPen be used with different insulins?

No. VetPen must be used with specially designed 3 mL cartridges containing 2.7 mL of 40 IU/mL concentration of Vetsulin, the world’s most trusted veterinary insulin, proven safe and effective for more than 20 years in hundreds of thousands of diabetic pets.* To avoid damaging VetPen and dosing errors, cartridges containing other insulin should not be used with VetPen.

* Vetsulin is known as Caninsulin outside the US.

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Using VetPen

How does selecting a dose with VetPen differ from drawing up a dose with a syringe?

While the overall injection process is similar, VetPen allows you to select doses more accurately. With just the turn of a dial, you can select a customized dose of insulin down to 0.5 units. And, with a push of the release button, the VetPen’s internal mechanism works to deliver the precise dose each and every time.

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How do I know when the injection is complete?

To make sure the pet’s dose is injected precisely and accurately, you need to hold down the release button until the arrow () points to the start line (—) on the dose selector. Then, wait at least 5 seconds before removing the needle from the skin. This allows for VetPen’s internal mechanism to optimally deliver the selected dose.

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Why does the VetPen need to be tested before each injection?

It is important to confirm that the VetPen and the needle are working properly to ensure that the pet receives an accurate dose of insulin. To do so, measure a small dose and ensure that the insulin flows freely through the needle.

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What should the insulin cartridge look like after mixing and priming?

Each cartridge contains 2 glass beads to help with the mixing of the Vetsulin before use. The cartridge should be thoroughly shaken before inserting it into the VetPen. After shaking, the insulin should appear uniformly milky. Do not use the cartridge if clumps persist after shaking thoroughly. Do not mistake the glass mixing beads for air bubbles, which should be removed during priming.

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Is VetPen reusable?

Yes. VetPen contains an insulin cartridge that allows multiple doses to be provided with minimal preparation time. When all the insulin has been used, simply remove the empty cartridge and insert a new one. Please note that sterile needles are designed for single use only and should not be reused. Tests show that VetPen lasts for at least 3,000 uses.11

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What type of needle is used with VetPen?

VetPen is designed to work optimally with 29 gauge/mm needles, which are small, thin, triple-sharpened, and specially lubricated. This equates to a lower penetration force and little to no discomfort for the pet. These are the only needles that should be used with VetPen.

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Can VetPen needles be reused?

No. Sterile needles are designed for single use only. A new needle should be used for each injection. A needle may become blunt or bent after use, which may cause the pet discomfort. The needle should be removed with the needle remover and safely disposed of immediately after use.

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Does VetPen need to be kept refrigerated when it contains an insulin cartridge?

Yes, VetPen should be refrigerated after a cartridge has been loaded and the VetPen is in use. Vetsulin cartridges should also be refrigerated before use. At all times, insulin cartridges should be protected from light. Vetsulin cartridges should not be frozen.

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What is the proper care of VetPen?

To clean VetPen, simply wipe with a damp cloth. Do not immerse it in water.

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Troubleshooting

Whenever experiencing any issues using VetPen, the first step should always be to confirm that air was properly removed from the cartridge through priming. Air bubbles in the cartridge can create multiple issues that result in the pet receiving too much or too little insulin.

What if insulin drips actively from the needle after injection?

This may be a sign that the needle may have been removed before the injection was completed. If the VetPen needle is removed from the skin too early, the pet did not receive its full insulin dose.

To make sure the pet receives its full dose, be sure to press the release button down fully and hold it until the arrow () points to the start line (—) on the dose selector. Then, to allow the VetPen to deliver the full dose, wait at least 5 seconds before removing the needle from the skin.

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What if the dose selector does not return to the start line after testing VetPen?

There are 4 likely causes for this:

  1. If the release button is not fully pushed toward the needle, it sometimes prevents the dose from being released completely. Be sure to push the release button down fully during each injection so that the dose selector can rotate back to the start line. Then, wait at least 5 seconds before removing the needle.
  2. You may be closing your hand too tightly around the dose selector, which can prevent it from fully rotating back to the start line. Avoid this from happening by holding the VetPen like a pen so that the dose selector is able to rotate freely after the release button has been completely depressed.
  3. The needle could potentially be blocked. Replace the needle on VetPen with a new one. It is important to use a new needle for each injection for hygiene and safety reasons.
  4. The cartridge may not have contained enough insulin for the full dose. If the cartridge is empty, replace it with a new one and complete the priming process. For additional information, see the next question.

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What if there is not enough insulin in the cartridge to complete an injection?

If there is not enough insulin left in the cartridge to give the pet its full dose, you can tell how many units of the dose were not given by looking at the number where the dose selector stopped. You may need to give the remainder of the dose. If so, write that number down.

Put in a new cartridge and prime (remove air from cartridge) and prepare the VetPen for use. Then, turn the dose selector to the number you wrote down and inject the pet as usual.

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What if a dose too large for the pet is selected?

If too high a dose has been selected, it is very important not to try to turn the dose selector back to a lower dose. This can damage or break the VetPen. The dose selector is designed to move from low to high numbers, but cannot be moved back from high to low numbers. If too high a dose has been selected, release the insulin through the needle into a tissue or swab by pressing the release button. Then select the correct dose.

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What if no insulin drips actively or squirts from the needle after priming or preparing for use?

There are 2 likely causes for this:

  1. The needle is blocked.
    To fix, replace the needle on VetPen with a new one. Remember to use a new needle for each injection. The needle is designed for single use only.
  2. The cartridge plunger is stuck.
    Follow these steps to fix this:
    • Place the protective cap back onto the needle and unscrew the cartridge holder.
    • Slide the release button towards the internal plunger and hold it until the arrow points to the start line.
    • Dial 2 units without screwing the device back together.
    • Push and hold down the release button until the arrow points to the start line.
    • Without rewinding the internal plunger, screw the cartridge holder and the VetPen body back together. This should release the cartridge plunger and expel some of the insulin.

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