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Safe storage, handling and administration of synchronization products

Jennifer Spencer for Progressive Dairy Published on 11 September 2019

During synchronization protocols, there are a variety of products which are used to manipulate the estrous cycle. Synchronization protocols are not “band-aids” and should not be used to overcome mismanagement. To achieve desired results, cows should be healthy, ready to breed and in appropriate body condition.

Employees must be able to accurately detect estrus and appropriately thaw semen and perform A.I. Additionally, employees must be trained in the safe handling, storage and administration of synchronization products.




The following discussion is intended for educational purposes only. Federal law restricts drugs listed to use by, or on the order of, a licensed veterinarian. Dairy producers should discuss proper dosage, usage and administration with their veterinarian, and train all personnel appropriately. Go to the Dairy Cattle Reproduction Council website: Dairy reproduction protocols for a review of synchronization protocols (in English and Spanish).

Overview of products

Synchronization products approved by the FDA include gonadotropin-releasing hormone (GnRH), prostaglandin F2a (PGF2a) and an intravaginal progesterone insert. GnRH will cause ovulation of appropriately sized follicles present on the ovary. Upon ovulation a corpus luteum (CL) forms and secretes progesterone while another follicular wave occurs, resulting in development of a dominant follicle. The corpus luteum is regressed by PGF2a resulting in a decline in progesterone, allowing for final maturation and ovulation of the dominant follicle. The purpose of an intravaginal progesterone insert is to provide an exogenous source of progesterone. The intravaginal progesterone insert is a unique tool as it will delay estrus in cattle which undergo natural CL regression during the treatment period. Moreover, administration of PGF2a near the end of the treatment ensures cattle which began the treatment early in the estrous cycle will have a CL responsive to PGF2a.


The majority of GnRH products should be refrigerated (35.6 to 46.4°F), while one product may be stored between 59 and 86°F. Upon first puncture of the vial, one GnRH product can be stored up to 77°F, but the rest must remain refrigerated. After first use, GnRH must be used or disposed of between 28 days and 6 months, depending on the specific product.

All PGF2a products should be protected from freezing and should be stored between 59 and 86°F. After first use, it is recommended the vial is not punctured more than 20 times and is used within 28 days or 12 weeks after first puncture, depending on the product. Any intravaginal inserts containing progesterone should be stored at room temperature, between 68 and 77°F.

To ensure proper storage of synchronization products, place a digital thermometer inside refrigerators and cabinets where products are stored. During inventory and ordering of new products, a best management practice is to check expiration dates and vial appearance. Discard outdated products according to manufacturer guidelines.



There are certain precautions which must be taken when handling synchronization products. No matter which product is being handled, gloves should always be worn, with extra gloves available in case they break or become torn. Direct contact of a synchronization product with the skin should be avoided. Accidental spillage on the skin or contact from a needle should be washed off immediately with soap and water. This is particularly important with PGF2a as it is easily absorbed through the skin and can cause abortion in pregnant women and bronchospasms in people with respiratory issues. Consult your veterinarian for recommendations regarding appropriate syringe and needle size for the product and route of administration. Additionally, needles should be changed frequently so they do not become dull.

Just like when handling synchronization products which are injected, it is important to wear gloves and carry extra pairs of gloves to avoid skin contact when handling intravaginal inserts containing progesterone. Intravaginal progesterone inserts come in zip-lock-type bags. When in the pens inserting progesterone inserts, it is often easier to carry a 5-gallon bucket containing bags of inserts to avoid running out and the need to retrieve more. Intravaginal progesterone inserts are placed in the vagina using an applicator. This applicator will be used on multiple cows and therefore needs to be cleaned between each cow. This can be done in a variety of ways, such as using diluted cleaner in another small bucket or spray bottle. Proper cleaning of the applicators can help to avoid bacteria entering the vagina.


After drawing up the product into the syringe, it is time to administer. The most common approved route of administration for GnRH and PGF2a is intramuscular (IM). All employees should be trained on how to prepare the product for administration, including placement and fastening of the needle on the syringe and how to draw the appropriate dose of the product into the syringe without air bubbles. Different size syringes, based on dose to be delivered, may ensure employees are able to deliver the desired dose. For employee and animal safety, personnel should be aware of where the product, needle and cows are at all times.

After drawing up the solution, the needle cap should be very carefully placed back on the needle until you are ready to administer it to ensure you do not poke yourself. Dairy producers should think Beef Quality Assurance and administer synchronization products in the neck of the cow. It is important to remember the animal to be treated will likely move as you approach. For example, a cow in a headlock, when approached from the front will tend to pull her head back. Pay attention as the cow will likely move forward and may hit you when you go to the side or over the top to administer the product.

To avoid injury, never place your hand or arm between the animal’s neck and the headlock. Instead, use the side between two bars. If administration is done over the headlocks, it is important to not only remember where the cow and neighboring cow are but also know where your hand is relative to the release mechanism (which could cause injuries to the fingers or hand). Awareness of animal behavior and your surroundings will minimize the potential for injury.

Administration of intravaginal progesterone inserts occurs behind the cow when she is in the headlock. This type of administration also requires diligence, awareness and proper training. When approaching a cow from behind, it is important to make your presence known. This helps to avoid frightening the cow and reduces the risk of injury. Once you’re behind the right cow, a gentle touch between the hooks and pins can also help let her know you’re there. Since cows cannot see directly behind them, making your presence known is important for the safety of the employee and cow.


When the cow knows you are there, you are ready to insert the intravaginal progesterone-containing insert. The progesterone insert is first placed inside of an applicator and then lube is added to the end of the applicator. Lube helps ease the insertion of the applicator into the vagina. Before inserting the progesterone insert, wipe any manure or dirt from the vulva with a clean disposable towel such as a paper towel. Next open the labia and insert the applicator at approximately a 30- to 45-degree angle allowing for ease of insertion. Gently slide the applicator into the vagina until there is resistance indicating you have reached the cervix and are completely in the vagina. Then, simply squeeze the handle at the end of the applicator, which will push the progesterone insert out into the vagina.

These inserts have wings at the end which help them stay in the vagina. It is important to not pull the applicator out when squeezing on the handle as this can also pull the progesterone insert out. Lastly, there is a plastic string which will hang out of the vulva. This is what is gently pulled on to remove the insert after the desired time. At times the string will be long because a cow may have a shorter vagina. For example, heifers will tend to have smaller and shorter vaginas as they have not calved. If the string is too long, it can be trimmed with a pair of scissors leaving 2 to 3 inches hanging out of the vulva. The reason for trimming this string if it is too long is because cows are naturally curious and playful, therefore, it may be pulled out. When trimming the string, remember to not cut the string too short; otherwise, the string could end up in the vagina and require digging it out during removal, which can introduce bacteria.

Take-home message

It is important to remember synchronization products are not “band-aids” and even the best management practices used for storing, handling and administrating synchronization products does not guarantee a successful breeding program. Rather, success is achieved through a valid veterinary-client relationship, training of employees, proper product storage, handling and administration, accurate recordkeeping, timing of the breeding program and proper A.I. technique.  end mark

Jennifer Spencer
  • Jennifer Spencer

  • Assistant Professor and Dairy Extension Specialist
  • Texas A&M AgriLife Research and Extension Center
  • Email Jennifer Spencer