Gene Expression of Fresh and Frozen/Thawed Canine Embryos.

BACKGROUND: Canine embryo cryopreservation and subsequent transfer are relevant in the use of reproductive technologies. OBJECTIVE: The purpose of this study is the identification and quantification of the gene expression BAX and Bcl2, AQP3, Na+/K+ ATPase alpha-1 and beta-1 and LIFr in canine embryos obtained in vivo and after freezing. MATERIALS AND METHODS: For the collection of embryos, the bitches were identified at pro-estrous until the detection of 80-90% superficial cells. After that, they were artificially inseminated with fresh semen. The embryos were collected after ovariohysterectomy. RNA was extracted and amplified, and embryos were randomly distributed into fresh (Fr) and frozen/thawed (Ft) groups. RESULTS: Eighteen blastocysts were collected from three bitches. Genes BAX, AQP3 and LIFr did not differ among the studied groups. CONCLUSION: We suggest, through these results, that the genes BAX, Bcl2, AQP3, Na + / K + ATPase alpha-1 and beta-1 and LIFr were expressed in canine blastocysts collected in vivo and after slow freezing cryopreservation.

Evaluation of follicular growth and tissue viability in vitrified/warmed domestic dog ovaries after in vitro culture.

Cryopreservation of gametes is an important tool to preserve fertility, but for most species, including domestic dogs, data regarding ovarian tissue cryopreservation are limited. We aimed to evaluate the follicular and tissue viability and follicular growth after in vitro culture of domestic dog ovarian cortical slices cryopreserved by vitrification. Ovarian cortex was obtained from ten pairs of ovaries from domestic dogs using two methods (A and B), one for each ovary from the same bitch. At least four slices for each method were obtained from each ovary, one was processed for histology and the other three were vitrified. When the vitrified slices were warmed, one slice from each method was processed for histology and the remaining two slices were cultured in vitro for 7 days, after which they were processed for histological evaluation. Density of follicles in fresh samples was similar for both methods. For Method A, density of secondary follicles decreased, while the density of primordial follicles was maintained throughout the process. For Method B, density of primary follicles decreased after 7 days of incubation, but density of secondary follicles increased, confirming follicular growth in Method B. Overall, there were no differences between Methods A and B in follicular integrity after incubation. Fresh samples showed better arterial, venous and follicle preservation, followed by vitrified-warmed samples, but no differences were observed between methods. In conclusion, the methodology used to isolate the ovarian cortex may affect tissue and follicle viability as well as follicular development during in vitro culture.

Lactate in bitches with pyometra.

Lactate is a compound produced by the anaerobic metabolism of glucose, and hyperlactataemia occurs when the rate of production of lactate exceeds the rate of elimination. This occurs in situations of hypoxia and tissue hypoperfusion. Lactate has been considered a useful prognostic indicator in critically ill patients. Pyometra is a disease of adult female dogs characterized by inflammation of the uterus with an accumulation of exudate, which occurs during the luteal phase. It is one of the most common diseases that occur in the genital tract of female dogs. A total of 31 dogs were diagnosed with pyometra. The diagnosis was confirmed at ultrasonography. Of the 31 dogs, 25 females had open cervix pyometra and six had closed cervix pyometra. Plasma lactate concentrations were determined by an enzymatic colorimetric method. The average concentration (±SD) of plasma lactate in all 31 bitches with pyometra was 3.55 ± 0.46 mm. Healthy dogs had plasma lactate concentrations between 0.3 and 2.5 mm (mean ± SD). Concentrations ranged from 0.8 to 2.9 mm when plasma lactate was measured with a portable device and 0.4-2.6 mm with the blood gas analyser. Even though plasma lactate values vary between several studies and equipment used to measure concentrations, our results for dogs with pyometra are higher indicating hyperlactataemia (Thorneloe et al. , Can Vet J 48, 283-288). Plasma lactate in dogs with closed cervix pyometra was mean ± SD and in dogs with open cervix pyometra, it was mean ± SD. The plasma lactate concentration in dogs with pyometra was higher than in healthy bitches, and there was no influence of patency of the cervix on the concentration of plasma lactate concentrations. Plasma lactate concentrations were similar for animals with open and closed pyometra (3.54 ± 0.52 to 3.64 ± 1.03 mm).

Histological characterization and immunohistochemical localization of ki-67 and VEGF factors in bitches' corpus luteum at cyclic and early and late gestational diestrous.

The luteal phase on pregnant and non-pregnant bitches is characteristic of this species and resembles significantly with respect to the growth pattern and luteal regression. Histological and immunostaining studies of the corpus luteum (CL) may help to elucidate differences between the CL of pregnant and non-pregnant bitches. The purpose of this study was to characterize histologically and localize by immunohistochemistry the cell proliferation (Ki-67) and vascular endothelial growth (VEGF) factors in the CL of pregnant and non-pregnant bitches. Eighteen bitches were analysed and distributed into three groups: In group I (gestational diestrous), seven bitches were subjected to two inseminations at 4 and 6 days after the pre-ovulatory LH surge and ovariohysterectomized (OSH) at 8-21 days after the first insemination. In group II (cyclic diestrous; control), 6 (Ki-67) or 8 (VEGF) bitches that were determined as non-pregnant were OSH at 12-25 days of the pre-ovulatory LH surge. In group III (late pregnancy), three bitches had their ovary removed during caesarean section at 62-64 days after the pre-ovulatory LH surge. Portions of the ovarian cortex containing CLs were cut and stored for histological and immunohistochemical analysis. Histological evaluation of the ovarian cortex showed a marked similarity in the morphological pattern among the CLs in all three groups. The morphology and expression pattern of VEGF and Ki-67 factors in CLs of cyclic and gestational diestrous bitches were similar but significantly lower than that of late pregnant bitches (p < 0.05).

Progesterone (PR), oestrogen (ER-α and ER-ß) and oxytocin (OTR) gene expression in the oviduct and uterus of pregnant and non-pregnant bitches.

The aim was to assess hormone receptor gene expression in the oviduct and uterus during canine pregnancy. Nineteen pregnant bitches divided into four groups were ovariohysterectomized (OVH) at either day 8, 12, 21 or 60 of pregnancy, and five non-pregnant females underwent OVH 12 days after the pre-ovulatory Luteinizant Hormone (LH) surge and served as controls. RT-qPCR for progesterone (PR), oestrogen (ER-α and ER-ß) and oxytocin (OTR) receptors was performed on the oviduct and uterine tissue. The mRNA PR expression in the uterus during early stages of pregnancy and the luteal phase was higher than at other times. The mRNA ER-ß expression in the oviduct during early pregnancy was less than in non-pregnant bitches. In the uterus, the mRNA ER-ß expression was higher in the initial stages of pregnancy. The ER-α expression was higher in the oviduct and uterus in advanced stages of pregnancy. The mRNA OTR expression in the oviduct was lower than in the uterus in control group. The expression of this receptor in oviduct and the uterus was higher in the final stages of pregnancy, when compared with other phases. These data suggested that the serum progesterone concentrations probably exert a direct control on the PR and ER (α and ß) expression and indirectly on OTR expression in the bitch oviduct and uterus.

Evaluation of sperm DNA peroxidation in fertile and subfertile dogs.

Oxidative stress (OS) has been recognized as one of the most important causes of male infertility. The antioxidant activities of seminal plasma and epididymal fluid are not enough to prevent OS, which can damage sperm membranes and DNA, so antioxidant supplementation has been used as a treatment of male infertility. The aim of this experiment was to evaluate the DNA peroxidation before and after antioxidant supplementation with vitamin C and E in dogs with and without fertility problems. A total of eleven dogs were used and were divided in two groups: fertile group (G1), dogs with normal spermiogram (n = 5); subfertile group (G2): dogs with low sperm count (<20 × 10(6) sptz/ml) and/or more than 30% of total sperm pathology (n = 6). Both groups received 500 mg/day of vitamin C and 500 mg/day of vitamin E for 60 days. A semen sample was collected before (M1) and after (M2) oral supplementation. Samples were analysed for DNA peroxidation by measuring the 8-hydroxy-2'-deoxyguanosine concentration. No significant difference was observed between groups at either time. Oral supplementation with 500 mg/day of vitamin C and 500 mg/day of vitamin E did not change the DNA peroxidation in fertile and subfertile dogs.

Osteopontin in seminal plasma and sperm membrane of dogs.

The objective of this work was to describe the presence of osteopontin (OPN) in canine seminal plasma and sperm membranes. A pool of seminal plasma and sperm membrane extract from 30 dogs was used. Polyacrylamide electrophoresis gels were performed and the bands were transferred to nitrocellulose paper and Western blot was undertaken using an antibody anti-OPN. Two and 12 bands were marked in the seminal plasma (77.2 and 15.6 kDa) and sperm membrane extracts (70.6-26.6 kDa), respectively. However, from 12 marked bands in the sperm membrane extract, only three (46.4, 37.7 and 36.5 kDa) were strongly marked. We conclude that, seminal plasma and sperm membranes from dogs contain different isoforms of OPN; yet, further studies will be necessary to determine their function in this species.

Fertilizing capacity of frozen epididymal sperm collected from dogs.

The collection of epididymal sperm may be a valuable tool for canine reproduction especially since it can enable collection of cells after death of a valuable dog. The aim of the present study was to evaluate the viability of epididymal sperm after freeze-thawing. Epididymides were obtained from four adult dogs by elective orchiectomy. The caudal portion of the epididymides and part of the deferential ducts were squeezed by means of an anatomic clamp into a Petri dish containing either 0.9% saline solution (Group 1) or Ringer solution without lactate (Group 2). Samples were centrifuged at 800 x g for 10 min, the supernatant was removed and the pellet was diluted in one step with a Tris/citric acid/OEP (Orvus Es Paste) extender containing 7% glycerol and subjected to semen freezing. Oocytes were obtained from canine ovaries, after ovariohysterectomy. Only oocytes that were approximately 100 mum in diameter, with a dark ooplasm surrounded by three- or four-well formed cumulus cell layers were used for sperm testing. Frozen semen samples were thawed in a water bath at 70 degrees C for 8 s and analysed at room temperature for sperm motility and velocity. Oocytes were incubated with spermatozoa in humidified atmosphere containing 5% CO(2) at 38 degrees C for 18 h. Morphological and functional characteristics of spermatozoa were similar in both groups. However, the percentage of sperm cells bound to oocytes was significantly higher in Group 2 than in Group 1. This result suggests that the Ringer solution without lactate was a more suitable medium for collecting epididymal canine sperm than 0.9% saline.

Ultrastructural characteristics of non-matured and in vitro matured oocytes collected from pre-pubertal and adult domestic cat ovaries.

The present study describes the ultrastructural characteristics of cat oocytes before maturation and after 12- and 24-h in vitro maturation (IVM). Oocytes were recovered from pre-pubertal and adult queen ovaries after ovariohysterectomy and a proportion were stored in glutaraldehyde at 4 degrees C until examination by transmission electronic microscopy (TEM). Those selected for maturation were cultured before TEM in DMEM for 12 and 24 h at 38 degrees C in a humidified environment of 5% O(2), 5% CO(2) and 90% N(2). Specimens were divided into six groups: non-matured oocytes from pre-pubertal queens (PP0), non-matured oocytes from adult queens (A0), 12-h in vitro matured oocytes from pre-pubertal queens (PP12), 12-h in vitro matured oocytes from adult queens (A12), 24-h in vitro matured oocytes from pre-pubertal queens (PP24) and 24-h in vitro matured oocytes from adult queens (A24). Across the treatment groups, it was possible to observe differences in the thickness of the perivitelline space, the penetration of cumulus cell projections forming a junctional complex, distribution and density of small vesicles, lipid droplets, microvilli, mitochondria and cortical granules and variable degrees of development of Golgi complexes. These findings demonstrated that ultrastructural analysis of oocytes matured in vitro is a valuable tool to evaluate oocyte cytoplasmic maturation and that this IVM protocol was efficient in inducing gradual morphological changes necessary for cytoplasmic maturation of pre-pubertal and adult cat oocytes.

Effect of progesterone and ionomycin on domestic cat sperm motility patterns and acrosome reaction.

This study was aimed at assessing the changes in sperm motion patterns and the percentage of acrosome reaction (AR) in domestic cat semen after treatment with either ionomycin or progesterone (P(4)). Ten ejaculates were collected from five tomcats using an artificial vagina, and were diluted, centrifuged and resuspended in a capacitation medium. Samples were evaluated and divided into seven equal aliquots and, after 2 h at 25 degrees C, were incubated for 30 min at 38 degrees C in 5% CO(2) and then analyzed. Computer-assisted sperm analysis and a combination of three fluorescent probes were used to assess sperm plasma, acrosomal membrane integrity and mitochondrial transmembrane potential. Thirty minutes after the start of incubation, P(4) was added (10 microg/ml) to the P1 group. Groups P2 and P3 were supplemented with P(4) (10 and 20 microg/ml, respectively) only after 2 h of incubation, and groups I1 and I2 were supplemented with ionomycin (4 and 8 mum, respectively) 2 h after incubation. Group E was supplemented with ethanol (0.6%) at 2 h after incubation and group C received no supplementation. Ionomycin and P(4) treatments led to a hyperactivation-like sperm motion and an increase (p < 0.05) in the percentage of AR. Although a higher (p < 0.05) percentage of AR was obtained in group I2 when compared with all P(4) groups, a decrease (p < 0.05) in total and progressive motility was observed in I2 group. As I1 group was similar to I2 to induce AR without diminishing sperm motility, we can conclude that ionomycin at 4 microm seems to be more suitable to trigger AR in domestic cat sperm.

Impact of 24-h cooling prior to freezing on the survival of domestic cat (Felis catus) epididymal sperm.

The aim of this study was to investigate the impact of a 24-h cooling period prior to freezing on domestic cat epididymal sperm viability. Fifteen tomcats were submitted to routine orchiectomy and sperm samples were retrieved from both epididymides in a Tris-glucose-20% egg yolk extender. For each tomcat, the diluted sperm was split into two equal volumes and cooled to 5 degrees C at a rate of 0.5 degrees C/min; one sample for 60 min (control) and the other for 24 h (cooled). After the cooling period, samples from both groups were frozen using an identical freezing protocol. Sperm samples were evaluated in three different periods: immediately after harvesting, after cooling at 5 degrees C for 24 h (cooled group) and after freezing-thawing of control and cooled groups. Evaluations consisted of sperm motility and progressive status, sperm morphology and plasma membrane integrity (PMI) using two fluorescent probes. After cooling for 24 h, a decrease (p < 0.05) in sperm motility, progressive status and PMI was observed when compared to sperm samples immediately after collection. Comparing the results obtained after thawing, no difference (p < 0.05) was found regarding sperm motility, progressive status, PMI and sperm morphology between control and cooled groups. The results from the present study show that cooling cat epididymal spermatozoa at 5 degrees C for 24 h prior to freezing does not lead to major damage of spermatozoa impairing the freeze-thaw process.

Is the right testis more affected by cryptorchidism than the left testis? An ultrasonographic approach in dogs of different sizes and breeds.

BACKGROUND: Considered the most common congenital testicular abnormality of companion animals and a predisposition factor to the development of testicular neoplasia, cryptorchidism is defined as the non-descent of one or both testes to their normal anatomical location. Data on the occurrence of cryptorchidism in Brazil are scarce. The purpose of this work was to verify the occurrence of cryptorchidism in dogs of different sizes and breeds. MATERIALS AND METHODS: Cryptorchidism identification was carried out by ultrasound scanning, from November, 1994 to March, 2007, at the Centre for Veterinarian Diagnosis and Support (Centro de Apoio e Diagnóstico Veterinário - CAD), in Rio de Janeiro. 4924 male dogs of different breeds were examined, revealing 403 (8.2%) cryptorchidism. RESULTS: In this study, occurrence took place more often on the right testicle (59.5%), more frequently displaying inguinal localisation (59.5%) and unilateral occurrence (70%). Regarding bilateral presentation, the symmetrical form was the most common (86.8%). Cryptorchidism was more common in the inguinal region of dog of small sized breeds and in the abdominal region in dogs of medium- and large-sized breeds. CONCLUSIONS: Ultrasound scan proved a valuable diagnosis tool for cryptorchid testes, giving precise localisation and parenchymal changes thus leading to a safe clinical treatment.

Testicular cytology by fine needle aspiration in domestic cats.

In cases where semen collection in tom-cats is not possible, FNA of testes is the alternative to evaluate sperm production. Although this technique for the diagnosis of fertility problems has been well discussed in other mammals (men, dogs, stallions), data for domestic cats are limited. Therefore, the aim of this study was to verify the reliability of FNA using needles of small diameters (22G and 29G) in testes of domestic cats of different ages to assess the spermatogenesis status and to present description of germ cells and Sertoli cells for cytological examinations. Thirty-four mixed breed cats aged between four months and two years presented for neutering to a Veterinary Hospital were used in this study. Under general anesthesia, testicular measures and FNA were followed by orchiectomy and imprints of the parenchyma of testes and epididymides. Cats were assigned into 3 groups: (G1) 10 cats aged less than 6 months, (G2) 14 cats aged between 6 months and one year and (G3) 10 cats aged more than one year. Cats weighted between 1.5 and 6.0 kg. The mean testicular volume (TV cm3) was 0.55 (G1), 1.18 (G2) and 2.66 (G3). Hemorrhages in the needle path were observed in more than 70% of testes. Few samples (4/68) were excluded due to blood contamination. All germ cells and Sertoli cells were identified and quantified in imprint and FNA smears. Incomplete spermatogenesis was observed in cats aged less than 6 months using both techniques (FNA and imprint); therefore, testicular FNA should not be recommended for cats at this age. Complete spermatogenesis was found in 64% of cats aged from 6 months up to one year and in all cats aged more than one year. There were no differences of Sertoli cell Index (SEI) and Spermatic Index (SI) between FNA and imprints of cats older than 6 months. In conclusion, FNA using needles of small diameter in the testes of domestic cats is viable, reliable and can be used as a tool for the analysis of the spermatogenesis status of cats older than 6 months, mainly in cases in which semen collection is not possible.

Characteristics of seminal plasma proteins and their correlation with canine semen analysis.

The objectives were to separate canine seminal plasma proteins (with SDS-PAGE) and to determine the correlation between specific proteins and semen characteristics. Three ejaculates from 20 mixed-breed dogs, of unknown fertility, were collected by digital manipulation. Ejaculate volume and color, sperm motility, sperm vigor, percentage of morphologically normal spermatozoa, and membrane integrity (hypoosmotic swelling test and fluorescent staining) were assessed. For each dog, seminal plasma was pooled from all three ejaculates and proteins were separated with SDS-PAGE, using polyacrylamide concentrations of 13% and 22% in the separation gels. After staining, gel images were digitized to estimate molecular weights (MW) and integrated optical density (IOD) of each lane and of individual bands. Total seminal plasma protein concentration was 2.19+/-1.56 g/dL (mean+/-SD; range 1.12-5.19 g/dL). A total of 37 protein bands were identified (although no dog had all 37 bands). In the 13% gel, molecular weights ranged from 100.6 to 17.1 kDa, with four bands (49.7, 33.2, 26.4, and 19.5 kDa) present in samples from all dogs. In the 22% gel, molecular weights ranged from 15.6 to 3.6 kDa, with nine bands (15.6, 13.5, 12.7, 11.7, 10.5, 8.7, 7.8, 5.6, and 4.9 kDa) present in samples from all dogs. Combined for both gels, the majority of bands (85%) had molecular weights <17 kDa, with B20 (15.6 kDa) in high concentrations in samples from all dogs. There were positive correlations (P < or = 0.01) between two bands, B4 (67 kDa) and B5 (58.6 kDa), and sperm motility (r=0.66 and r=0.46), sperm vigor (r=0.56 and r=0.66), percentage of morphologically normal spermatozoa (r=0.55 and r=0.59), the hypoosmotic swelling test (r=0.76 and r=0.68), and fluorescent staining (r=0.56 and r=0.59), respectively. In conclusion, 37 proteins were identified in seminal plasma; two were significantly correlated with semen characteristics.

Morphological and functional characteristics of chilled semen obtained from domestic feline epididymides (Felis catus).

The objective of this study was to determine morphological and functional characteristics of semen retrieved from the feline epididymis before and after cooling. Sixteen adult male cats were orchiectomized. The distal portion of the epididymis and proximal part of the deferent ducts were dissected and squeezed to obtain their content. After centrifugation, the supernatant was removed, sperm were resuspended in a 0.9 mL Tris-fructose-citric acid extender containing 20% egg yolk, aliquoted into three 0.3 mL samples, placed in a refrigerator (4.8 degrees C) and cooled (0.5 degrees C/min). Semen evaluations were performed on four occassions: immediately after epididymal sperm retrieval (T0), and at 24 h (T1), 48 h (T2) and 72 h (T3) after cooling. On each occasion, progressive motility, vigor and sperm morphology were determined. Mean motility and vigor decreased (P < 0.05) between each successive examination. Although the majority of sperm cell damage occurred within the first 24 h, there was a decrease (P < 0.05) in mean percentage of morphologically normal sperm between T0 and each evaluated time (T1, T2, T3) after cooling, due to an increase in coiled and bent sperm tails. Further studies are needed to evaluate the effects of cooling on the fertilizing capacity of cat epididymal spermatozoa in assisted reproduction programs.

Cryopreservation effects on domestic cat epididymal versus electroejaculated spermatozoa.

Frozen-thawed epididymal spermatozoa have already been successfully used in artificial insemination in the domestic cat, proving to be a valuable resource for the reproduction of felid species, which are threatened with extinction. The aim of this study was to compare the effects of freezing and thawing on domestic cat semen collected by electroejaculation (EL) and from the epididymides (EP) and vasa deferentia. Ten adult cats were anesthetized, electroejaculated and immediately thereafter, orchiectomized. Epididymal spermatozoa were collected through the compression of caudae epididymidis and vasa deferentia. Spermatozoa were frozen-thawed following a single protocol. Sperm motility, sperm progressive status (0-5), plasma membrane integrity and morphology (light and transmission electron microscope) were assessed on two occasions, immediately after collection and after freezing and thawing. There were no significant differences between the electroejaculated and epididymal fresh or frozen-thawed spermatozoa for any of the variables. However, the incidence of acrosome defects after freezing and thawing increased by 19% based on light microscopy, whereas ultrastructural images revealed acrosome damages in most sperm cells. Since these acrosomal changes are known to affect sperm fertilising capacity, further studies are needed to optimize cryopreservation techniques for epididymal as well as electroejaculated domestic cat spermatozoa.

Effects of four anaesthetic protocols on the neurological and cardiorespiratory variables of puppies born by caesarean section.

Twenty-four bitches which had been in labour for less than 12 hours were randomly divided into four groups of six. They all received 0.5 mg/kg of chlorpromazine intravenously as premedication, followed 15 minutes later by either 8 mg/kg of thiopentone intravenously (group 1), 2 mg/kg of ketamine and 0.5 mg/kg of midazolam intravenously (group 2), 5 mg/kg of propofol intravenously (group 3), or 2.5 mg/kg of 2 per cent lidocaine with adrenaline and 0.625 mg/kg of 0.5 per cent bupivacaine with adrenaline epidurally (group 4). Except for group 4, the bitches were intubated and anaesthesia was maintained with enflurane. The puppies' heart and respiratory rates and their pain, sucking, anogenital, magnum and flexion reflexes were measured as they were removed from the uterus. The puppies' respiratory rate was higher after epidural anaesthesia. In general the puppies' neurological reflexes were most depressed after midazolam/ketamine, followed by thiopentone, propofol and epidural anaesthesia.

Amniocentesis and biochemical evaluation of amniotic fluid in ewes at 70, 100 and 145 days of pregnancy.

The objectives of this study were to determine the technical viability of amniocentesis in sheep and to observe biochemical changes in the amniotic fluid components. Amniotic fluid samples were collected by puncture in the greatest curvature of the uterine horn at days 70, 100, and 145 of pregnancy. The surgical procedure for collection of amniotic fluid samples was safe and efficient. For three stages of pregnancy, the following results were obtained: pH values 8.36, 7.34 and 7.37; glucose concentrations, 16.06. 8.58, and 3.79g/dl; urea values, 42.68, 33.53, and 25.49mg/dl; creatinine, 0.85, 5.04, and 11.25g/dl; Gama-GT enzyme, 12.58, 14.20, and 12.30UI/l; sodium concentrations, 146.60, 129.42, and 103.8mmol/l: potassium concentrations, 9.79, 6.15, and 8.65mmol/l; chloride, 96.59, 85.28, and 65.35mmol/l; total protein, 0.14, 0.23, and 0.24g/dl, respectively.

Ovarian activity reversibility after the use of deslorelin acetate as a short-term contraceptive in domestic queens.

The objective was to evaluate ovarian activity reversibility in domestic queens after short-term contraceptive treatment with deslorelin acetate. Ten mature queens were used. In all queens, the estrous cycle was evaluated every 72 h by vaginal cytology (VC) and behavior assessments. When queens had VC characteristic of interestrus or diestrus, one deslorelin acetate implant (4.7 mg) was placed in the subcutaneous tissue of the interscapular region (day of insertion = Day 0). Thereafter, VC was performed every 48 h and on Day 90, implants were removed. At Day 100, estrus and ovulation were induced with 100 IU eCG (im), followed by 100 IU hCG (im), 84 h later (Day 103.5). Queens were ovariohysterectomized on Day 106. Corpora lutea (CL) were counted, oviducts were flushed, and oocytes were identified, isolated and stained to assess viability. In all queens, blood samples for plasma progesterone concentrations were collected once a week, from Days -21 to 106. After deslorelin acetate application, four queens had VC and behavior typical of estrus, and one ovulated. Furthermore, ovulation occurred in three queens that did not have VC or behavior consistent with estrus. After the initial ovarian stimulation, all females had anestrous VC during the deslorelin treatment period. Implants were readily removed. Following implant removal, all females responded to treatments to induce estrus and ovulation. There were (mean ± SEM) 13.1 ± 5.5 CL and 8.1 ± 5.5 oocytes per queen; the oocyte recovery rate was 56.8 ± 25.4% and all recovered oocytes were viable. We concluded that deslorelin acetate can be used as a reversible short-term contraceptive in domestic cats, because estrus and ovulation were successfully induced following implant removal.