Controlled internal drug release (CIDR) devices are used in livestock for the synchronization of

estrus The estrous cycle (, originally ) is the set of recurring physiological changes that are induced by reproductive hormones in most mammalian therian females. Estrous cycles start after sexual maturity in females and are interrupted by anestrous ...

. They are T-shaped devices with a silicone-coated nylon core. The silicone coating is impregnated with

progesterone Progesterone (P4) is an endogenous steroid and progestogen sex hormone involved in the menstrual cycle, pregnancy, and embryogenesis of humans and other species. It belongs to a group of steroid hormones called the progestogens and is the majo ...

. CIDRs are inserted intra-vaginally using a specialized applicator. The flexible wings collapse for facilitated insertion and expand once placed appropriately within the vagina. The expansion of the wings retains its position; CIDRs have very high retention rates that may exceed 97%.Eric Grant. 2006. Understanding CIDR. ''National Association of Animal Breeders.'' Feb 1, 2006. Retrieved March 20, 2012, from Beef Magazine: http://beefmagazine.com/mag/beef_understanding_cidr A thin nylon tail remains exteriorized and is used for removal. Once inserted, CIDRs provide

slow-release Modified-release dosage is a mechanism that (in contrast to immediate-release dosage) delivers a drug with a delay after its administration (delayed-release dosage) or for a prolonged period of time (extended-release R, XR, XLdosage) or to a spe ...

administration of progesterone, which artificially extends the

luteal phase The corpus luteum (Latin for "yellow body"; plural corpora lutea) is a temporary endocrine structure in female ovaries involved in the production of relatively high levels of progesterone, and moderate levels of estradiol, and inhibin A. It is th ...

. Plasma progesterone levels rapidly increase upon insertion, and remain relatively consistent while in place. Following CIDR removal, progesterone levels decrease rapidly. Occasionally, vaginal irritation may occur. This is normal and does not impact the effectiveness of the device or the animal’s performance. There are several types of CIDRs available, including CIDR-B for cattle, CIDR-S for sheep and CIDR-G for goats. CIDRs are similar to the

progesterone-releasing intravaginal device Progesterone devices are broadly used in the control of reproductive management in livestock. They work by increasing circulating plasma progesterone levels with the following consequences: # Progesterone suppresses the secretion of gonadotropin-re ...

(PRID), also used for synchronization of estrous cycles in livestock.

Uses

CIDRs are approved for use in both

beef cattle Beef cattle are cattle raised for meat production (as distinguished from dairy cattle, used for milk production). The meat of mature or almost mature cattle is mostly known as beef. In beef production there are three main stages: cow-calf opera ...

and dairy heifers in Canada and the United States. CIDRs contain 1.9g of progesterone in Canada and 1.38g in the United States. The CIDR-S is licensed for use in sheep and goats in

New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island coun ...

and Australia. The CIDR-G is also suitable for use in ewes, lambs and goats.

Oestrus synchronization

Cattle

In cattle, CIDR-Bs are often used with synchronization protocols. The product label typically indicates that, in conjunction with an appropriate synchronization protocol, CIDRs should be left in for 7 days. Ovsynch is a particular protocol that is often followed. These estrus synchronization protocols allow Fixed Time

Artificial Insemination Artificial insemination is the deliberate introduction of sperm into a female's cervix or uterine cavity for the purpose of achieving a pregnancy through in vivo fertilization by means other than sexual intercourse. It is a fertility treatment ...

to be used, giving herd managers more accurate control. The use of CIDRs with synchronization protocols helps improve reproductive performance by reducing the inefficiency associated with estrus detection. Although there is variability in the response to estrus synchronization, studies show consistently high pregnancy rates following Fixed Time Artificial Insemination with CIDR synchronization of

ovarian follicle An ovarian follicle is a roughly spheroid cellular aggregation set found in the ovaries. It secretes hormones that influence stages of the menstrual cycle. At the time of puberty, women have approximately 200,000 to 300,000 follicles, each with ...

development.

Sheep and goats

Previously, intravaginal progestogen sponges were a common method of estrus manipulation in ewes. The development and success of CIDRs has increased their use in sheep and goats. Unlike intravaginal progestogen sponges, CIDRs do not absorb or impede drainage of natural vaginal secretions, offering a cleaner method of delivery. They also allow administration of a natural form of hormone, as opposed to the potent analogues used in sponges. A dose of 550 mg of progesterone has been found to be effective in controlling estrus and

ovulation Ovulation is the release of eggs from the ovaries. In women, this event occurs when the ovarian follicles rupture and release the secondary oocyte ovarian cells. After ovulation, during the luteal phase, the egg will be available to be fertilize ...

in sheep.

Treatment of follicular cysts

CIDRs may be used as a treatment in cows with follicular cysts. Follicular cysts in cattle affect a significant proportion of

dairy cows Dairy cattle (also called dairy cows) are cattle bred for the ability to produce large quantities of milk, from which dairy products are made. Dairy cattle generally are of the species '' Bos taurus''. Historically, little distinction was ...

in several countries, and hinder the dairy industry by extending the period from calving to conception. CIDRs help by reducing the

Luteinizing Hormone Luteinizing hormone (LH, also known as luteinising hormone, lutropin and sometimes lutrophin) is a hormone produced by gonadotropic cells in the anterior pituitary gland. The production of LH is regulated by gonadotropin-releasing hormone (GnRH) ...

pulse frequency and inducing

atresia Atresia is a condition in which an orifice or passage in the body is (usually abnormally) closed or absent. Examples of atresia include: *Aural atresia, a congenital deformity where the ear canal is underdeveloped. * Biliary atresia, a condition i ...

of cystic follicles. This may also allow affected cows to be re-used in

breeding Breeding is sexual reproduction that produces offspring, usually animals or plants. It can only occur between a male and a female animal or plant. Breeding may refer to: * Animal husbandry, through selected specimens such as dogs, horses, and r ...

embryo transfer Embryo transfer refers to a step in the process of assisted reproduction in which embryos are placed into the uterus of a female with the intent to establish a pregnancy. This technique (which is often used in connection with in vitro fertilizati ...

programs.

History

CIDRs were developed by AHI Plastic Moulding Company in

Hamilton, New Zealand Hamilton ( mi, Kirikiriroa) is an inland city in the North Island of New Zealand. Located on the banks of the Waikato River, it is the seat and most populous city of the Waikato region. With a territorial population of , it is the country's ...

, in conjunction with the

Ministry of Agriculture and Forestry (New Zealand) The Ministry of Agriculture and Forestry (in Māori, ''Te Manatu Ahuwhenua, Ngāherehere'') was a state sector organisation of New Zealand which dealt with matters relating to agriculture, forestry and biosecurity. It was commonly known by its ...

. Developmental trials began in 1981. The CIDR-S was licensed in 1986 and the CIDR-G in 1988.

References

{{reflist, colwidth=30em Veterinary drugs Animal breeding Theriogenology