Intrauterine devices influence prostaglandin secretion by equine uterus: in vitro and in vivo studies.

BACKGROUND: Intrauterine devices (IUD) are used in the veterinary practice as the non-pharmacological method of oestrus suppression in mares. When placed in the uterus, IUD create a physical contact with the endometrium that mimics the presence of an equine embryo. However, the mechanism of their action has not been fully elucidated. The objective of the present study was to examine the effect of mechanical stimulation of IUD on mare`s endometrium in both in vitro and in vivo study. For this purpose, we demonstrated the effect of IUD on prostaglandin (PG) F2α and PGE2 secretion, and mRNA transcription of genes involved in PG synthesis pathway in equine endometrial cells in vitro. In the in vivo study, we aimed to compare short-term effect of IUD inserted on day 0 (oestrus) with day 5-6 post-ovulation (the specific time when embryo reaches uterus after fertilization) on PG secretion from equine endometrium. To determine the long-term effect on PG synthase mRNA transcription, a single endometrial biopsy was taken only once within each group of mares at certain time points of the estrous cycle from mares placement with IUD on days 0 or 5-6 post-ovualtion. RESULTS: We showed for the first time that the incubation of the endometrial cells with the presence of IUD altered the pattern of PG synthase mRNA transcription in equine epithelial and stromal endometrial cells. In vivo, in mares placement with IUD on day 0, PGE2 concentrations in blood plasma were upregulated between 1 and 6, and at 10 h after the IUD insertion, compared with the control mares (P < 0.05). Moreover, the decrease of PTGFS mRNA transcription on day 16- 18, associated with an elevation in PTGES mRNA transcription on day 20 -21 of the estrous cycle in endometrial biopsies collected from mares placement with IUD on days 5-6 suggest an antiluteolytic action of IUD during the estrous cycle. CONCLUSION: We conclude that the application of IUD may mimic the equine conceptus presence through the physical contact with the endometrium altering PG synthase transcription, and act as a potent modulator of endometrial PG secretion both in vitro and in vivo.

Preliminary study of the contraceptive effect of a self-assembling intrauterine device (iUPODs) in mares maintained in a paddock with a fertile stallion.

There is an urgent need for practical methods of population control (i.e., contraception and/or sterilization) for free-roaming (i.e., "wild" or "feral") horses and burros on Western Public Lands in the United States. The objective of this study was to evaluate the contraceptive efficacy of a novel self-assembling three-part polymer-coated magnetic intrauterine device termed as an intrauterine POD (self-assembling; iUPOD) when there are natural breeding conditions when iUPOD use was managed by veterinary professionals with no prior experience with the device. Six mares were administered an iUPOD and were then housed continuously with a fertile stallion for 91 days. The intrauterine POD retention and contraceptive efficacy were 100%. Two mares had prolonged corpus luteum function (for 37 and 91 days) immediately after iUPOD placement. For the estrous cycles of the other mares, the duration of diestrus was 7.8 ± 2.7 days (mean ± S.D.). Four of the mares (67%) became pregnant when in a paddock with the same stallion the year after iUPOD removal. These results are encouraging for use of the iUPOD as a practical and reversible method of fertility control in free-roaming horses and burros.

Modification of O-ring intrauterine devices (IUDs) in mares: Contraception without estrus suppression.

A significant welfare concern for those within the horse industry is that of the overpopulation in free-roaming horses in the western US. The goal of the present study was to identify a humane and inexpensive means of providing contraception and reducing pregnancy rates in a way that could be applied to free-roaming horses on the western U.S. open range lands. A series of studies was conducted utilizing the previously-described silastic O-ring intrauterine devices (IUDs). Throughout these studies pregnancy was successfully prevented in mares with an O-ring IUD, but collective retention rates failed to exceed 50% regardless of size or durometer (material hardness/malleability). When the O-ring IUDs were compared to the recently-described Y-design IUDs (Holyoak et al., 2021) the Y-design IUDs had a markedly greater rate of retention; therefore, the Y-design IUDs would be most appropriate for potential use in free-roaming horses. Assessment of mare records revealed that the vast majority of mares continued to have ovulations and mating continued to occur while the IUDs were in place. A few mares had multiple small ovarian follicles when the IUD was in utero. Findings indicate that utilizing an IUD with the expectation of estrus suppression in mares would fail to be fruitful.

An intrauterine device with potential to control fertility in feral equids.

Fertility control of feral equids is difficult. A 4-month pilot study was conducted with a hormone-free intrauterine device (iUPOD). There was evaluation of i) device retention; ii) contraceptive efficacy; iii) fertility following device removal; iv) effects of device on estrous cycle periodicity and; v) abundance of biofilm on devices after removal from the uterus. The iUPODs were inserted trans-cervically in eight mares at random stages of the estrous cycle. Mares were confined in a paddock with a stallion the following day and remained with the stallion for 120 days. Transabdominal detection of the iUPOD, using a non-invasive handheld magnetic detector wand, was performed weekly. Mares were examined using transrectal ultrasonography on days 0 (Time at insertion = day 0), 14, and 30, and subsequently every third week to assess number and size of follicles, corpora lutea, and whether there was intrauterine fluid (IUF) present. The mares and stallion were observed daily for mating behavior. Weekly samples were assayed for progesterone (P4) at day 0 and until 3 weeks subsequent to stallion removal. None of the mares became pregnant while fitted with the iUPOD. Two of four mares conceived within 30 days subsequent to iUPOD removal. Three of eight mares fitted with the device had periods greater than 14 days with P4 concentrations <1 ng/mL, and seven of eight mares had periods greater than 14 days with P4 concentrations>1 ng/mL. There was a marked abundance of biofilm on devices of two mares at the time of device removal.

Cyclooxygenase-2 is inhibited in prolonged luteal maintenance induced by intrauterine devices in mares.

Treatment with intrauterine devices (IUD) prolongs luteal phases in mares, but the mechanism for this has not been fully elucidated. The aims of the present study were to examine how IUDs affect the uterus to induce longer luteal phases, particularly the role of cyclooxygenase-2 (COX-2) in the maintenance of the corpus luteum (CL). Twenty-seven reproductively normal mares were included: 12 were inseminated (AI), and 15 were fitted with IUDs. Blood samples for progesterone were obtained on Days 0, 3, 5, 7, 9, 11, 13, 14, and 15 (relative to day of ovulation). The groups were further divided into non-pregnant (AI-N, n = 4), pregnant (AI-P, n = 8), normal (IUD-N, n = 8) and prolonged luteal phase (IUD-P, n = 7) based on ultrasonic examinations and serum progesterone concentrations on Days 14 and 15. Blood sampling to quantify the PGF2α metabolite (PGFM) was performed through a catheter hourly from 15:00 to 20:00 h on Day 14, and from 6:00 until 13:00 h on Day 15. On Day 15, a low-volume uterine lavage followed by an endometrial biopsy was performed. Estradiol concentration in the Day 15 serum and lavage fluid was determined, while the abundance of COX-2 was evaluated in the biopsy specimens using western blotting (WB) and immunohistochemistry (IHC). All pregnant mares were negative for COX-2 in IHC samples and 5 of 8 were negative in WB samples while all mares of the IUD-N group were positive for COX-2. Of the seven mares in the IUD-P group, five and four were negative for COX-2 with the IHC and WB samples, respectively. The results from this study indicate that IUDs, when effective, suppress COX-2, leading to the inhibition of PGF2α release and maintenance of CL.

Complications associated with intrauterine glass marbles in five mares.

CASE DESCRIPTION 5 mares were evaluated because of reproductive complications following long-term (> 1 year) use of intrauterine glass marbles for estrus suppression. CLINICAL FINDINGS 3 mares had 1 intrauterine glass marble, and 2 mares had 2 intrauterine glass marbles. On examination, 2 mares had signs of chronic endometritis, and 3 had signs of pyometra. Marbles or glass shards adhered to the endometrium were identified by means of hysteroscopy in 3 of 5 mares. Five of 7 marbles had surface imperfections or were broken. TREATMENT AND OUTCOME All patients were treated with uterine lavage and intrauterine and systemic administration of antimicrobials chosen on the basis of results of bacterial culture and susceptibility testing. Two of 5 mares were treated with intrauterine Tris-EDTA. One mare underwent 3 unsuccessful embryo transfer procedures and was subsequently lost to follow-up. One mare was euthanized because of severe vaginal and cervical adhesions and chronic vaginal discharge. Three mares had no apparent signs of reproductive disease at the time of follow-up but were not rebred. CLINICAL RELEVANCE Results of the present small case series suggested that use of intrauterine glass marbles should be discouraged because of the potential for severe reproductive consequences.

Effects of Intrauterine Devices in Mares: A Histomorphological and Immunohistochemical Evaluation of the Endometrium.

Oestrous suppression by intrauterine devices (IUDs) is caused by prolongation of luteal function, but the biological mechanism is unknown. The aim of the study was to investigate mechanisms which could explain the action of IUDs. Thirty mares were age-matched and either inseminated (AI, n = 15) or fitted with an IUD (IUD, n = 15) and subsequently divided into four groups: AI-P, pregnant (n = 8); AI-N, non-pregnant (n = 7); IUD-P, prolonged luteal phase (n = 7); and IUD-N, normal luteal phase (n = 8). The median ages were 5.5 and 7 years in AI-P and IUD-P groups and 14 and 11 years in AI-N and IUD-N groups, respectively. On Day 15 after ovulation, an endometrial biopsy was obtained to study histomorphological and immunohistochemical expression patterns of uterine proteins (uteroferrin, UF; uterocalin, UC; uteroglobin, UG), oestrogen and progesterone receptors (ER, PR), proliferation marker Ki-67 and content of inflammatory cells. Expression of UF was higher in IUD mares; the difference between pregnant and IUD-P mares was significant. Mares exhibiting a prolonged luteal phase (AI-P, IUD-P) showed only mild angiosclerosis and lower expression of both ER and PR than mares with a normal luteal phase (AI-N, IUD-N). No significant differences were detected in the numbers of inflammatory cells, with the exception of macrophages, which were more numerous in AI-P than AI-N mares. Although inflammatory cells were not detected in IUD mares, increased UF levels may indicate chronic inflammation. Young age and normality of the endometrial blood vessels may improve the efficacy of IUDs.

The effect of intra-uterine devices on the reproductive physiology and behaviour of pony mares.

Spherical (35 mm diameter) glass intra-uterine devices (IUDs) are commonly understood to modify sexual behaviour in performance mares. The effect of IUDs on the endocrinology (luteinising hormone, oestradiol, progesterone, testosterone), ovarian and uterine function, sexual and social behaviours associated with the ovarian cycle were evaluated during the natural breeding season in nine, nuliparous pony mares (4.6±0.5 years old, 230±12 kg bodyweight). Age and weight-matched groups were allocated to sham-treatment (n=5) or IUD-implantation (n=4) groups. Fifty complete ovarian cycles were evaluated, with 26 ovarian cycles monitored for the nine mares prior to treatment and a further 12 cycles were evaluated for mares in each of the groups post-treatment. Detailed characterisation of cyclic reproductive changes in the pony may be of value for controlled breeding programmes. The presence of an IUD was well-tolerated, but failed to modify any recorded aspect of reproductive physiology or behaviour.

Contraceptive efficacy of a novel intrauterine device (IUD) in white-tailed deer.

Overabundant white-tailed deer (Odocoileus virginianus) pose risks to property, health, and safety of human beings. Public concerns about lethal management can impair efforts to address these issues, particularly in urban settings. Several techniques developed for reducing reproductive output of deer have limited utility because they require repeated dosing to achieve permanent effect and face uncertain regulatory approval for use beyond experimentation. From 10 August 2006 through 30 December 2007, we evaluated the contraceptive efficacy of copper-containing intrauterine devices (IUDs) implanted trans-cervically in white-tailed deer at the E.S. George Reserve in Pinckney, Michigan. Intrauterine devices were implanted before (n=9) and shortly after (n=10) the breeding season. Post-breeding season IUD treatment was in conjunction with a 5cm(3) dose of 5mg/ml prostaglandin F(2alpha) (PGF(2alpha)), delivered subcutaneously. Intrauterine devices reduced pregnancy rates when administered prior to breeding (P<0.001) and prevented pregnancy for up to 2 years (the duration of the study). Two of 8 does that received IUDs prior to the breeding season and survived to the end of the study became pregnant (due to loss of the implant) during the second year while all (n=16) does without implants conceived. Cervical changes associated with early pregnancy made trans-cervical implantation after the breeding season challenging, and resulted in improperly placed IUDs in 2 treated does. The apparent expulsion of IUDs by pregnant does that received the combined treatment after breeding suggests IUD treatment should be limited to the pre-breeding season. Intrauterine devices show potential as a tool for small-scale deer population management via non-steroidal reproductive inhibition.

Efecto de la sincronización del estro con prostaglandina-f2a vs CIDR + 500 UI de eCG en ovejas bergamacia durante el inicio de la fase luteal / Effect of estrus synchronization with prostaglandins-F2a vs CIRD + 500 IU of eCG in bergamacia ewes during early luteal phase

Con el objeto de evaluar los efectos de la sincronización del estro con PGF2a vs CIDR + 500 UI de eCG, sobre el tiempo de presentación de estro, ovulación y las concentraciones plasmáticas de hormonas esteroidales durante el inicio de la fase luteal en ovejas, se seleccionaron 14 hembras Bergamacia distribuidas en dos grupos: el Grupo uno (Control), sometido a dos aplicaciones de prostaglandina-F2a (PG), con un intervalo de nueve días, y el Grupo dos, tratado con el dispositivo intravaginal impregnado con progesterona (CIDR) durante 12 días y 500 UI de eCG. La presentación del estro fue de 100%. Entretanto, el intervalo estro-ovulación fue de 36,0 ± 0,72 horas en el grupo dos. El grupo control tratado con PG presentó un intervalo estro-ovulación de 53,42 ± 3,0 horas (P<0,001). Hubo diferencia significativa (P<0,01) en las concentraciones plasmáticas de P4 entre los tratamientos. Los animales del Grupo dos presentaron aumentos significativos (P < 0,01) en las concentraciones plasmáticas de P4, desde el sexto hasta el décimo día después de la ovulación, comparados con las concentraciones de los animales control. Del mismo modo, también se constató una diferencia significativa en la interacción tratamiento y día (P< 0,05). Las concentraciones de E2 en el plasma sanguíneo fueron estadísticamente diferentes (P< 0,001) entre el grupo control y el grupo sincronizado con el CIDR + eCG. Fueron observadas diferencias significativas (P< 0,001) en las concentraciones plasmáticas de E2 entre los tratamientos después del día ovulatorio (día cero), siendo además constatada diferencia significativa entre los días (P< 0,001) y en la interacción tratamiento y día (P< 0,05). Se puede concluir que, la sincronización del estro en hembras Bergamacia, utilizando el CIDR + eCG disminuyó el intervalo estro-ovulación y provocó aumento de las hormonas esteroidales en plasma.

An experiment was conducted to investigate the effects of estrous synchronization with PGF2a vs cidr + 500 IU of eCG on interval to estrus, ovulation and steroidal hormones plasma concentrations during early luteal phase in sheep. Fourteen ewes were treated, distributed in two groups: Group 1 (Control), synchronized with two injections of prostaglandin-F2a (PG), given 9 days apart, and Group 2, was treated with CIDR for 12 days and 500 IU of eCG. Estrous presentation was 100%. The interval estrus-ovulation was 36.0 ± 0.72 h in Group two. The control group presented an interval estrus-ovulation of 53.42 ± 3.0 hours (P<0.001).There were significant difference (P < 0.01) in P4 plasma concentrations among treatments. In Group 2, the animals showed significatives increases (P < 0.01) in P4 plasma concentrations during day 6 until day 10 when compared with control animals. It was observed significative difference at interaction treatment by day (P < 0.05). E2 plasma concentrations were statistically differents (P < 0.001) among control group and synchronized group with CIDR + eCG. There were significant difference (P < 0.001) in E2 plasma concentrations among treatments after ovulation day (Day 0) with significative difference among days (P < 0.001) and interaction treatment x day (P < 0.05). These results indicated that estrous synchronization in Bergamacia females, using CIDR + eCG diminished interval estrus-ovulation and elicit higher levels of steroidal hormones in plasma.

A new strategy for superior reproductive performance of ewes bred out-of-season utilizing progestagen supplement prior to withdrawal of intravaginal pessaries.

Two experiments were conducted to examine the effect of progestagen supplement 24h prior to intravaginal pessary withdrawal on reproductive performance of seasonal anestrous ewes. Ewes in each experiment were allocated to treatment and control and all were induced to estrus using either intravaginal MAP (Exp. 1; n=24) or CIDR-G (Exp. 2; n=28) pessaries for 12 days. Half of the ewes in each experiment were supplemented 24h before withdrawal of pessaries with either 10mg oral MAP tablets (Exp. 1) or 25mg i.m. progesterone (P(4)) administration (Exp. 2; P(4)-supplement-treated group). Fertile rams were allowed with the ewes at sponge removal (Day 0, 0h) and estrus was monitored at 6-h intervals for 3 days. Blood samples were collected for measurements of P(4) (Exp. 1 and Exp. 2) and LH (Exp. 2). In both experiments, the percent of ewes in estrus was greater (P<0.05) and intervals to estrus were longer (P<0.05) in progestagen-supplement-treated than control ewes. In Exp. 2, the occurrence and magnitude of LH surges were greater (P<0.01) and intervals to onset of LH surge were longer (P<0.01) in P(4)-supplement-treated than control ewes. In Exp. 2, P(4) supplement elevated P(4) levels from 1.8+/-0.1ng/mL on Day -1 to 4.2+/-0.3 on Day 0 (P<0.001). Following pessaries removal, P(4) concentrations fell to basal values on Day 1 in both groups and remained low until Day 5. Then, P(4) concentrations increased and remained elevated through Day 19 in all (100%) progestagen-supplement-treated in Exp. 1 (12/12) and Exp. 2 (14/14) and in only 5/12 (41.7%) and 6/14 (42.9%) control ewes, respectively. These ewes were confirmed pregnant by ultrasonography and lambed on Day 149.2+/-0.2 following Day 0. In conclusion, progestagen supplement 24h prior to removal of pessary can be used successfully to improve reproductive performance of ewes bred out-of-season.

Mechanisms behind intrauterine device-induced luteal persistence in mares.

Intrauterine glass balls are used to prevent oestrous signs in sports mares, but the mechanism of action is unknown. It has been suggested that the glass ball can mimic an embryo or act via an induced chronic uterine inflammation and absent or continuous low-grade prostaglandin (PG) release. The purpose of this study was to induce prolonged luteal function in mares using a small intrauterine device (IUD) and to study the mechanisms behind prolonged IUD-induced luteal function. A uterine swab and a biopsy specimen were obtained in early oestrus. A water-filled plastic ball, diameter 20mm and weight 3.6g, was inserted into the uterus 2-4 days after ovulation; the control mares underwent similar cervical manipulation without ball insertion. The mares were examined three times per week until day 23 and twice weekly thereafter until they returned to oestrus (transrectal palpation, ultrasonography and progesterone determination). The location of the IUD was recorded and ultrasound scans were video-recorded to assess the frequency of uterine contractions. When the mare returned to oestrus, a uterine swab and biopsy specimen were obtained and the bacteriological, cytological and histological (inflammation and glandular dilation) results compared with the samples obtained before the IUD insertion. The PG F(2alpha) metabolite levels were measured in the plasma of four control mares and eight IUD mares on days 11-16. The IUD induced a prolonged luteal phase in 75% of the mares (9/12; IUD-P); the mean dioestrous length was 57.0 days. The three mares that did not respond to the IUD (IUD-N) showed a mean dioestrous length of 15.7 days and the 12 control mares 16.1 days. The inflammation and glandular dilation scores were not significantly different in pre- and post-manipulation biopsy specimens. Although locational changes of the IUD were observed, they occurred over very small distances and were mostly limited within the body-bifurcation area. The IUD-N and control mares showed increased uterine contractility 11-16 days post-ovulation, whereas the IUD-P mares did not. The control mares (n=4) and IUD-N mares (n=2) showed increased PG levels from day 14 post-ovulation, while the IUD-P mares (n=6) showed basal levels only. We concluded that the IUD did not cause continuous PG release and suggest that close contact of the IUD with the endometrium may prevent the endometrial cells from releasing PGF(2alpha).

Aplicación de dispositivos intravaginales impregnados con progesterona para la sincronización del estro y ovulación en yeguas pura sangre de carrera / Application of an intravaginal progesterone device for the oestrus and ovulation synchronization of thoroughbred mares

Se utilizaron distintos dispositivos intravaginales (DI) impregnadas con progesterona para determinar el tiempo entre de colocación del DI y el momento cuanto el folículo preovulatorio alcanzó más de 35 mm (FPO > 35mm) y desde este momento hasta la ovulación. Con 30 yeguas Pura Sangre de Carreras (PSC) se formaron dos grupos al azar: Grupo 1, n=15; DI con 1,38 g de progesterona y 25 mg i.m de benzoato de estradiol (BE), Grupo2, n= 15; DI con 1,0 g de progesterona y 25 mg i.m de BE. Se realizaron ecografías desde el 4to día de colocado el DI hasta FPO > 35mm, en ese momento se retiraron los DI y presentaron las yeguas para detectar estadísticamente el estro y monitorear la ovulación mediante ecografía. La presentación del estro fue analizada estadísticamente mediante el test de Fisher, el tiempo de colocado el DI hasta FPO > 35mm y la ovulación, mediante el test de Mann Whitney. La presentación del estro fue de 80 y 93,3%, en 12 yeguas ante el calentador (14). El promedio desde inserción de DI hasta FPO > 35mm y la ovulación fue 150 ± 20, 96 ± 34 h en G1 y 149 ± 19, 79 ± 24 h en G2. Se concluye que en yeguas PSC es posible retirar los DI al día 6-7 y que el contenido de progesterona en los DI no tuvo efecto sobre la presentación del estro, tiempo hasta FPO > 35mm y a la ovulación (P>0,05).

Efecto de eCG e inseminación laparoscópica sobre el comportamiento reproductivo en ovejas F1 (damara x merino) / Effect of eCG and laparoscopic insemination on reproductive performance in F1 (damarax merino) ewes

Cuarenta y cinco ovejas F1 (Damara x Merino) con 123 ± 27,6 días post parto mantenidas en clima tropical húmedo fueron utilizadas para evaluar el efecto de dosis de gonadotropina coriónica equina (eCG) en el porcentaje de sincronización del estro, fertilidas por inseminación laparoscópica (IL) prolificidad. Para sincronizar estros en la ovejas se les colocó un dispositivo intravaginal (CIDR) inpregnado con 0,03 de progesterona por 12 d. Las ovejas fueron asignadas aleatoriamente a tres tratamientos. T1: CIDR y monta natural; T2: CIDR más 150 UI de ecG e IL a las 42-46 h al retiro del dispositivo con semen de machos de la raza Damara; T3. CIDR más 300 UI de eCG e IL a las 42-46 h de retiro del dispositivo con semen de machos de la raza Damara. La fertilidad del estro sincronizado fue de 40; 40 y 46,6% para T1, T2 y T3 respectivamente, no encontrando diferencias (P> 0,05) entre ellos. El porcentaje de prolificidad presentó diferencias (P<0,05) entre tratamientos y fue de 100; 100 y 133,3% para T1, T2 y T3. Estos resultados permitirán hacer ajustes en estudios futuros sobre la metodología de programas de sincronización de estros e inseminación artificial laparoscópica a tiempo fijo con semen congelado, con el objetivo de mejorar el comportamiento reproductivo de ovejas F1 (Damara x Merino) bajo condiciones de clima tropical húmedo en México.

Contraception in the chimpanzee: 12-year experience at the CIRMF Primate Centre, Gabon.

The Primate Centre of the International Center for Medical Research in Franceville, Gabon (CIRMF) has had a chimpanzee (Pan troglodytes) colony for more than 20 years. A contraceptive policy was started in 1990, following a rapid increase in the number of individuals in the 1980s. Intrauterine devices were first used in 24 females; 10 failures occurred over a period of about 4 years. Depo-provera was then used in 28 chimpanzees for between 4 months and 4 years; 10 failures occurred, the animals gained weight, and cyclic swelling of the external genitalia was markedly modified. Starting in late 2000, 25 females received progestin implants; only one failure has so far occurred, and the main side effect is a complete abrogation of cyclic sexual swelling.

Intrauterine device for contraception in dogs.

A new intrauterine device for contraception was tested on nine bitches. After it had been implanted, the bitches were mated but none of them became pregnant. Over a two-year period no side effects were observed, except in a bulldog bitch in which signs of oestrus persisted until the device had been removed.

Pharmacokinetics and residual behaviour in milk of oxytetracycline in cows following administration of uterine pessaries.

The plasma kinetics and residual depletion in milk of cows treated by the intrauterine route with pessaries containing oxytetracycline (OTC) were evaluated. The antibiotic was administered to five healthy Friesian cows at a dosage of 3g/head in the early post partum phase. Blood samples were collected before and at different time intervals (3, 6, 12, 24, 48, 72, 84, and 96 h) after treatment. Milk was drawn before treatment and at 12-h intervals for 4 consecutive days. Samples were analysed by a high-performance liquid chromatography method and the pharmacokinetic parameters were processed using the minimum Akaike information criterion estimation (MAICE) test. The mean values obtained indicated a relatively low area under the concentration time curve (25.19+/-12.61 microg/mg per h) and maximum plasma concentration (Cmax) (0.549+/-0.278 microg/mL) with delayed time to Cmax (11.71+/-4.15 h) and elimination half-life (21.96+/-4.42 h). A similar pattern could be shown for milk, in which measurable residual levels are found in two out of five animals until the 72nd hour after treatment. Data obtained demonstrate that OTC administered as a solid form is poorly and slowly absorbed from the uterus of cows.

Use of intrauterine devices (IUDs) for contraception in the common chimpanzee (Pan troglodytes).

The common chimpanzee (Pan troglodytes) is a species phylogenetically very close to man. It was not many years ago that the captive population of chimpanzees (P. troglodytes) was considered at risk because of perceived problems with reproductive success. With the potential need for many individuals for research in a variety of areas, particularly in the areas of parasitic and viral infections, an NIH-funded program was established to promote the breeding of the species. That program, the 'National Chimpanzee Breeding and Research Program', was highly successful, so successful, in fact, that there is now a surplus of animals available for current research programs. This situation has prompted the use of intrauterine devices (IUDs) as a method of fertility control. Overall, this method is successful and associated with a failure (of pregnancy) rate similar to that reported in the human. Physical and logistic constraints, however, render the method less than ideal for situations where a pregnancy rate of zero is desired.