Studies in the female domestic dog demonstrate that luteinizing hormone (LH) and follicle-stimulating hormone (FSH) have secretion patterns that are pulsatile, are inhibited by oestradiol during pro-oestrus and surge to maximal values before ovulation. Studies in ovariectomized bitches suggest that the periovulatory surge is triggered by a preovulatory decline at late pro-oestrus in the oestrogen:progesterone ratio. During the 3-8-month non-seasonal anoestrus, FSH concentrations usually are 50-100% of those of the periovulatory peak, whereas LH concentrations are only 10-20% of peak values. In ovariectomized bitches FSH concentrations are often 5-10 times preovulatory peak values, whereas LH concentrations are only the same as, or double, peak values. Increased LH concentration and pulse frequency are associated with the termination of anoestrus. Treatment with gonadotrophin-releasing hormone (GnRH) pulses or infusions of GnRH agonists can induce fertile oestrus in early anoestrous bitches, as can treatment with a dopamine agonist, presumably by suppression of prolactin secretion. Between 4 months of age and pubertal pro-oestrus at 8-12 months of age, serum concentrations of FSH and LH are similar to those in adult anoestrus, and are suppressed during chronic infusion of GnRH agonist. The latter resulted in a reversible inhibition of puberty during 1 year of treatment. Studies in vivo have shown that LH and prolactin are luteotrophic throughout most of the luteal phase. LH stimulated progesterone synthesis by bitch luteal cells in vitro in the presence or absence of stimulant factors or steroid precursors present in serum.
Avaliação da influência do ciclo estral e da hiperplasia endometrial cística-piometra sobre a sensibilidade à insulina e característica da ligação hormônio-receptor em músculo de fêmeas caninas.
O diabetes mellitus canino (DMC) é uma afecção freqüente em cães, apresentando diversos fatores etiológicos envolvidos, como raça, predisposição genética, alimentação desquilibrada, obesidade ou presença de antagonismos hormonais; como é o caso do diestro (fase luteal do ciclo reprodutivo). O DMC é mais freqüente em fêmeas, e cerca de 70% das fêmeas que desenvolvem diabetes encontram-se na fase do diestro. Muitos autores consideram o DMC, com início no diestro, análoga ao diabetes mellitus gestacional humano. Durante a fase do diestro, a progesterona induz não só resistência à insulina, mas também acarreta uma série de alterações no endométrio. Uma maior sensibilidade uterina à progesterona pode acarretar a ocorrência de hiperplasia endometrial cística (HEC) e piometra, condição séptica / inflamatória limitante à vida se não tratada. A ocorrência de qualquer anormalidade inflamatória, infecciosa, hormonal ou neoplásica apresenta um importante potencial de estimular resistência à insulina. O objetivo deste trabalho foi avaliar a sensibilidade à insulina durante as diferentes fases do ciclo estral e na presença da condição patológica hiperplasia endometrial cística. Ao todo 44 pacientes foram avaliadas neste estudo, sendo dividas nos grupos anestro (n = 11), estro (n = 7), diestro (n = 14), HEC (n = 5) e piometra (n = 8). Todas as pacientes passaram por avaliação física e exames laboratoriais de saúde geral. As pacientes que se enquadraram nos critérios de inclusão foram encaminhadas para realização de IVGTT (teste de tolerância à glicose intravenosa) após jejum de 8 a 12 horas (MATTHEEUWS et al., 1987), após o qual foi realizada a cirurgia de castração das pacientes, de forma eletiva das pacientes na diferentes fases do ciclo estral ou como parte do tratamento nas pacientes com HEC ou piometra. Durante o procedimento operatório foram colhidas amostras de músculo para estudos de ligação hormônio receptor conforme Kucharski et al., (1997) e estudos de fosforilação conforme Kucharski et al., (1999). Para análise dos resultados o trabalho foi dividido em dois capítulos: o primeiro sobre o impacto do ciclo estral sobre a sensibilidade à insulina; e o segundo sobre o impacto do complexo HEC-piometra sobre a sensibilidade à insulina. A análise dos resultados mostra que a ocorrência do estro e do diestro afeta a sensibilidade tecidual à insulina reduzindo a afinidade da ligação insulina-receptor nos sítios de alta afinidade e também leva a menor capacidade de fosforilação basal dos resíduos de tirosina. Contudo, a maior capacidade de ligação destes sítios tende a contrabalançar a menor sensibilidade tecidual a insulina não sendo possível observar estado de intolerância à glicose nestas pacientes. Entretanto, nas pacientes com HEC-piometra uma intensa resistência à insulina e intolerância à glicose pode ser observada, especialmente, em decorrência de uma severa redução na afinidade da ligação hormônio-receptor nos sítios de alta afinidade não acompanhada por um aumento na capacidade de ligação. A fosforilação dos resíduos de tirosina nas pacientes com piometra não difere da menor fosforilação basal observada nas pacientes em diestro. Na literatura consultada não foram encontrados estudos de alterações nos receptores de insulina ou nos eventos pós-receptor na etiopatogênia do DMC. Desta forma foi demonstrado pela primeira vez, alterações importantes na sensibilidade tecidual à insulina durante as fases do estro e diestro, bem como na presença de HEC-piometra, as quais podem causar uma maior predisposição à ocorrência do DMC; especialmente se as pacientes estiverem expostas a outros fatores de risco já descritos para ocorrência de diabetes.
Cystic endometrial hyperplasia complex
The cystic endometrial hyperplasia complex is an alteration of the uterus of bitches and queens. It is directly related to the repeated exposition or drawn out of hormones estrogen and progesterone. It is characterized by an exaggerated response along the production and release of the secretion of the endometrial glands and dependent on the degree of hydratation and present protein in this secretion, the alteration could be considered hydrometra or mucometra. Pyometra is considered when due to individual factors or because of virulence and proliferation of invading bacteria in the fluid causing other secondary signs and symptoms that can provoke death of the patient.
Neoplasias mamárias em cadelas: influência hormonal e efeitos da ovario-histerectomia como terapia adjuvante.
As neoplasias mamarias constituem aproximadamente 50% dos tumores diagnosticados em cadelas. Apesar dosharmónios sexuais femininos desempenharem papel fundamental no desenvolvimento desses tumores em mamíferos, o valor da supressão hormonal pela ovário-histerectomia como auxiliar no tratamento do tumor e mama em caninos permanece controver- so. Discute-se ainda se a realização da ováriohisterectomia após o diagnóstico influencia ou não o crescimento e progressão do tumor na glândula afetada ou em outras glândulas mamarias. O objetivo desta revisão é discutir alguns aspectos relacionados à influência hormonal na etiologia de tumores mamarias em cadelas, assim como o valor terapêutico da castração, quando realizada no momento da mastectomia.
Plasma oestrogen levels during the canine oestrus cycle.
Peripheral plasma samples were obtained during pro-oestrus and oestrus from two adult Beagle bitches and from one animal (bitch 124) during its first oestrous cycle. The animals were housed in a constant environment kennel and each showed a normal oestrous cycle as judged by clinical appearance, vaginal cytology and behavioural tests; in addition, a rise in plasma progesterone was noted during late oestrus and early metoestrus (Christie, Bell, Horth & Palmer 1971). Plasma oestrogens were measured by the radioimmunoassay technique of Abraham (1969), with modifications. No separation of oestradiol and oestrone was undertaken and the results are thus an estimate of total immunoreactive oestrogens. The water blank for the method was 16 ± 6·5 (S.D.) pg/ml while the solvent blank was 19 ± 4·7 pg/ml. The results were corrected for the solvent blank. The recovery of oestradiol added to water was 102 ± 12 (S.D.)%, and to plasma from a bilaterally ovariectomized, hemi-adrenalectomized.
Reproductive endocrinology of bitches.
Domestic dogs are mono-oestrous and predominantly non-seasonal breeders with ovarian cyclicity unrelated to uterine function. During the first phase of dioestrus or pregnancy luteal function seems to be independent of gonadotrophic support and the gradual decline of progesterone concentration thereafter occurs in spite of an increased availability of prolactin and luteinising hormone (LH). Thus, the mean area under the curve (AUC) for LH (ng per 360 min ml−1) increased from 1672 in early dioestrus to 2510 in late dioestrus and from 2940 on day 20 to 5089 on day 55 of pregnancy. LH pulse frequency remained unchanged. An induced release of LH during each quarter of dioestrus had no immediate effect on progesterone concentration but production over the whole period of dioestrus was increased (P < 0.03). Results from blocking cyclooxygenase activity indicated that the rather precipitous luteolysis prior to parturition was PgF2α-mediated. During anoestrus LH pulse frequency did not change. The AUC for LH decreased from late dioestrus to early anoestrus (6332 vs. 3257 ng per 360 min ml−1) and increased from mid to the end of anoestrus (5830 ng per 360 min ml−1). Only during the terminal phase of anoestrus could resumption of ovarian activity be induced by treatment with oestradiol-17β. There was a depression of oestradiol-17β during mid anoestrus while it increased at the end of anoestrus.
Sexual characteristics of female dogs during successive phases of the ovarian cycle.
Five female beagles were examined periodically throughout their second biannual cycle of proestrus, estrus, metestrus, and anestrus for fluctuations in several physiological and behavioral charateristics. Physiological measures included plasma levels of estradiol and progesterone as well as the vulvar swelling and vaginal bleeding that begin with proestrus and continue in estrus. Behavioral tests revealed changes in female receptivity, attractivity, and proceptivity. Estradiol increased prior to the onset of proestrus and declined during estrus. Progesterone levels were low during most of proestrus, increased from the beginning to the end of estrus, and remained elevated during the first month or more of metestrus. While they were in proestrous females were not receptive but they and their vaginal secretions were highly attractive to males. Attractivity remained high throughout estrus and declined abruptly in the next 24 hr. Receptivity increased over the first 3 days of estrus and continued at a high level until the last 3 days during which it decreased slightly, and then dropped nearly to zero within the next 24 hr. “Sexual reflexes” of the vulva, tail, and hindquarters followed the same course of changes described for attractivity. Proceptive behavior, including seeking proximity to caged males and display of solicitation responses during mating tests was characteristic of females during proestrus and estrus but uncommon or absent in other phases of the cycle. It is hypothesized that in the natural cycle, attractivity and proceptivity develop during proestrus as a consequence of rapidly increasing secretion of estrogen. The onset of receptivity is due to synergistic action of estrogen and progesterone. Estrogen secreted during proestrus primes the system, and progesterone secreted just before and during estrus activates it. Termination of receptivity is thought to be due to the marked decline in estrogen, to inhibition by high concentrations of progesterone, or to a combination of these factors.
Emprego da neuroleptanalgesia com Droperidol e Fentanil em cesariana de cadelas.
No presente trabalho os autores descrevem uma das modalidades de neuroleptanalgesia na operação cesariana de cadelas. Foram usados 12 animais em condições clínicas variadas. A dose do droperidol (neuroléptico) foi de 2,0mg e a do Fentanil (analgésico), foi de 0,04mg para cada quilograma de peso vivo, mantendo a proporção de 50:1. A intervenção tinha início 10 minutos após a aplicação do Droperidol: via intramuscular e da anestesia local em linha de incisão. O Fentanil somente era aplicado no momento da exposição dos cornos uterino, para evitar a depressão respiratória nos fetos. A maioria dos animais, podia se manter de pé ou, em decúbito esterno-abdominal, logo após a intervenção cirúrgica.
Colpocitologia em cadelas comuns.
Dez cadelas jovens, sem raça definida, foram submetidas à colpocitologia, estando oito delas em proestro e duas em anestro. Na esfoliação epitelial sob estímulo estrogênico (proestro e estro), houve aumento do número de células superficiais, ao passo que a maior descamação das células profundas do epitélio vaginal (parabasais) correspondeu às fases de formação e atividade do corpo lúteo (metaestro e diestro). Já no diestro houve decréscimo do número de células superficiais e aumento das parabasais e das intermediárias. Nas fases de diestro e anestro evidenciou-se leucocitose, enquanto a presença de eritrócitos foi máxima na fase de proestro e decresceu lentamente nas fases seguintes.
Aplasia segmentar de corpo uterino em cadela sem raça definida: relato de caso
Relata-se um caso de aplasia segmentar parcial de corpo uterino em uma cadela sexualmente madura, em anestro, sem raça definida, em bom estado clínico geral. À necropsia, não foram identificadas alterações dos demais órgãos genitais, à exceção do corpo uterino, que apresentava redução de espessura numa extensão de 2mm na parte mediocaudal, com ausência de lúmen nesse ponto, e hidrometra em sua porção cranial e cornos uterinos. A avaliação histológica evidenciou redução da espessura total do corpo uterino no seu terço mediocaudal, porém presentes perimétrio, miométrio e endométrio, mas ausência de lúmen, bem como redução da espessura total da parede uterina nos cornos, com redução do número de glândulas endometriais. Nos ovários, foram identificados folículos em vários estádios de desenvolvimento e corpos lúteos em regressão, indicando que a cadela estava em atividade cíclica normal.
Alterações morfológicas no ovário e corno uterino da cadela. IV. Neoplasias ovarianas.
As neoplasias ovarianas, em cadelas criadas nas regiões metropolitanas de Belo Horizonte e do Rio de Janeiro, tendem a ocorrer com maior freqüência em animais velhos, atingindo, em todas as faixas etárias, 7,0% dos animais. Dentre os 14 casos diagnosticados, nove eram neoplasias epiteliais (cinco cistadenomas papilíferos, dois adenomas papilíferos, um cistadenocarcioma), coexistindo, em cinco animais, com o complexo hiperplasia endometrial cístico-piometrítico. Nos demais casos, quatro referiam-se a tumor de células da granulosa e um, a tumor metastático (linfossarcoma) em ambos os ovários e cornos uterinos correspondentes.
Alterações Morfológicas no Ovário e Corno Uterino da Cadela. III. Complexo Hiperplasia Endometrial Cístico-Piometrítico.
Descreve-se a ocorrência do complexo hiperplasia endometrial cistico-piometrítico em cadelas oriundas das regiões metropolitanas do Rio de Janeiro e Belo Horizonte. No total de 200 animais, 27 (13,5%) estavam afetados da enfermidade, com maior concentração de casos na faixa etária dos cinco aos 10 anos e nos tipos II, III e IV da classificação de Dow. Houve nítida tendência de associação do complexo com a presença de corpos lúteos ativos.
Estudo clínico e histopatológico de alterações útero ovarianas de cadelas submetidas à ovariohisterectomia. I - Tumor de células da granulosa.
Descreve-se a ocorrência de tumor de células da granulosa em cadelas provenientes do Hospital da Escola de Veterinária e de Clínicas Veterinárias de Belo Horizonte. No total de 70 animais, 16 (22,05%) apresentaram o tumor com maior concentração entre oito e 11 anos de idade. Houve associação ao complexo hiperplasia endometrial cístico-piométrico em 11 casos, à hemorragia endometrial em quatro casos e ao leiomioma em um caso. Clinicamente, as cadelas apresentaram prostração, anorexia, hipertermia, vômito, diarréia, poliúria, polidipsia, hiperplasia vaginal, secreção vaginal purulenta, metrorragia, alopécia, hiperpigmentação da pele no dorso e região dos membros posteriores.
Diurnal variation of serum progesterone, but not relaxin, prolactin, or estradiol-17B in the pregnant bitch.
The concentrations of progesterone (P), relaxin (Rlx), estradiol (E2) and PRL were measured by specific RIAs in serum samples collected twice daily at 8:00 am and 3:00 pm at weekly intervals after mating and until whelping in five Labrador Retriever bitches. From weeks 3 to 6 of pregnancy, P exhibited a conspicuous and statistically significant diurnal pattern (P < 0.05), its serum concentration being approximately twice as high at 8:00 am as at 3:00 pm. A similar but nonsignificant trend was observed weeks 2, 7, and 8, and the overall ratio of the am/pm P concentrations was 2.4 ± 0.28 (P < 0.001). Rlx, E2, and PRL did not show a diurnal pattern at any time during pregnancy.
The glandular sources and regulation of secretion of Rlx were further investigated. Rlx bioactivity was detected in canine placentas and ovaries, providing supportive evidence that these organs may be a dual source of the hormone in canine pregnancy. Injection of ovine PRL in three pseudopregnant bitches significantly increased serum P concentration as compared with seven untreated pseudopregnant controls, but Rlx was not detectable in serum before, during or after PRL treatment.
Changes in LH, progesterone and sexual behavior associated with preovulatory luteinization in the bitch.
LH and progesterone were assayed in plasma collected at 0800, 1600 and 2400 h daily from each of 6 Beagles during proestrus and estrus. The bitches’ sexual behavior in response to males was assessed daily. Preovulatory LH surges lasting 24-40 h peaked (4.4-11.1 ng/ml) at 2400 or 0800 h between three days before and one day after the onset of estrus. Estrous behavior in each bitch was observed only after an increase in progesterone. The initial increase in progesterone occurred either just prior to, or concomitant with, the initiation of the LH surge. Mean (± SEM) progesterone at -56, -40, -24, -16, -8, 0, 24 and 48 h from the LH peak was 0.7 ± 0.1, 0.9 ± 0.1, 1.2 ± 0.1, 1.4± 0.2, 1.5 ± 0.2, 2.6 ± 0.3, 3.2 ± 0.4 and 5.4 ± 0.6 ng/ ml. LH at the same times was 1.7 ± 0.3, 1.1 ± 0.2, 1.5 ± 0.3, 1.8 ± 0.3, 4.9 ± 1.0, 7.3 ± 1.0, 2.0 ± 0.3 and 1.4 ± 0.4 ng/ml. Ovulation time in the bitch was estimated by correlating results of gross and histological examination of ovaries removed from each of 10 Beagles during proestrus or estrus with LH and progesterone measured in plasma collected two to three times a day prior to obtaining the ovaries. Ovaries were removed from 6 of these bitches at approximately 4, 8, 20, 38, 44 and 50 h after the LH peak, when plasma progesterone was 1.3, 2.8, 4.2, 3.3, 4.4 and 6.9 ng/ml, respectively. The respective ovulated:nonovulated mature follicle ratios were 0:10, 0:6, 0:7, 0:8, 4:3 and 11:0. The sexual behavior of 6 ovariectomized bitches was observed daily for 5 weeks during which 16 days of estrogen treatment was initiated either 8 days before or 8 days after initiation of a 16 day progesterone treatment. Initial progesterone (4.8 ± 0.4 ng/ml plasma) had no effect. Induction of full sexual receptivity occurred 8 days after superimposing estrogen (65 ± 5 pg/ml plasma) on progesterone. Initial estrogen caused bitches to be attractive to males but failed to induce any acceptance of the males. Full sexual receptivity was induced within 18 h of superimposing progesterone on estrogen, was not affected by removal of estrogen 8 days later but was lost entirely within 18 h of progesterone removal after another 8 days.
The results suggest that, in the bitch: 1) ovulation occurs between 1 day before and 5 days after the onset of estrus and approximately 38-44 h following the LH peak; 2) follicle luteinization and increased progesterone secretion begins just prior to or concomitant with initiation of the LH surge some 60-70 h prior to ovulation and 3) the initial preovulatory rise in progesterone is synergistic with the preceding late-proestrous estrogen peak in eliciting estrous behavior.
Biology and endocrinology of ovulation, pregnancy and parturition in the dog.
There is considerable variation among bitches in commonly encountered intervals between cycles (5-12 months), durations of anoestrus (1-8 months), durations of follicular phase pro-oestrus (3-21 days) and periovulatory oestrous behavior (3-21 days), intervals from preovulatory LH surge to oestrus onset (-2 to 5 days), and intervals from fertile mating to parturition (57-68 days). The extent of variation within bitches ranges from slight to great. However, there appears to be very little variation in the intervals from LH surge to ovulation (2 days), to post-ovulatory oocyte maturation (approximately 4 days), to implantation (approximately 18 days), to selected developmental stages of pregnancy, or to parturition (64-66 days). There are no tests diagnostic of early pregnancy. The onset times of persistent pregnancy-specific changes have been estimated, including radio-opaque fetal details (Day 46), elevated blood prolactin values (Day 35), elevated blood relaxin values (Day 25), echogenic heart beats (Day 24) and embryonic vesicles (Day 19), and potentially palpable uterine enlargements (Day 21). As in humans, there is an anaemia of pregnancy involving a 30% reduction in haematocrit and an increased incidence of insulin resistance during the second half of gestation. Ovarian progesterone is required throughout pregnancy. LH and prolactin are luteotrophic in the pregnant bitch as well as during the 2-month luteal phase of the non-pregnant bitch. Parturition follows a luteolysis which occurs during an increase in prostaglandin F-2 alpha that begins 36 h pre partum. Factors regulating the duration of anoestrus are not known but termination of anoestrus is associated with increased pulsatile secretion of LH.
Ovulation timing. Concepts and controversies.
While the luteinizing hormone (LH) surge has long been accepted as the key event in the estrous cycle of the bitch, historically, there has been no practical way to identify it. In the past, the veterinary practitioner had to rely on general and/or subjective information received from vaginal cytology, physical examinations, and observations. With the recent development of in-clinic progesterone and LH assays, and the wider availability of laboratory quantitative progesterone assays, the LH surge can either be identified directly or estimated by the detection of changes in progesterone. As a result, ovulation time can now be predicted with high accuracy in a private practice setting.
Canine placenta: a source of prepartal prostaglandins during normal and antiprogestin-induced parturition.
Expression of cyclooxygenase 2 (COX2, now known as PTGS2), prostaglandin E2 synthase (PTGES, PGES), and prostaglandin F2A synthase (PGFS), of the respective receptors PTGFR (FP), PTGER2 (EP2), and PTGER4 (EP4) and of the progesterone receptor (PGR, PR) was assessed by real-time PCR, immunohistochemistry (IHC), or in situ hybridization (ISH) in utero/placental tissue samples collected from three to five bitches on days 8–12 (pre-implantation), 18–25 (post-implantation), and 35–40 (mid-gestation) of pregnancy and during the prepartal luteolysis. Additionally, ten mid-pregnant bitches were treated with the antiprogestin aglepristone (10 mg/kg bw (2x/24 h)); ovariohysterectomy was 24 and 72 h after the second treatment. Plasma progesterone and 15-ketodihydro-PGF2A (PGFM) concentrations were determined by RIA. Expression of the PGR was highest before implantation and primarily located to the endometrium; expression in the placenta was restricted to the decidual cells. PTGS2 was constantly low expressed until mid-gestation; a strong upregulation occurred at prepartal luteolysis concomitant with an increase in PGFM. PGFS was upregulated after implantation and significantly elevated through early and mid-gestation. PTGES showed a gradual increase and a strong prepartal upregulation. PTGFR, PTGER2, and PTGER4 were downregulated after implantation; a gradual upregulation of PTGFR and PTGER2 occurred towards parturition. ISH and IHC co-localized PGFS, PTGFR, PTGES, and PTGS2 in the trophoblast and endometrium. The changes following application of aglepristone were in the same direction as those observed from mid-gestation to prepartal luteolysis. These data suggest that the prepartal increase of PGF2A results from a strong upregulation of PTGS2 in the fetal trophoblast with the withdrawal of progesterone having a signalling function and the decidual cells playing a key role in the underlying cell-to-cell crosstalk.
Effects of prostaglandins on ovarian blood flow in the bitch.
Oestrous and anoestrous mongrel dogs were anaesthetized with chloralose–urethane. In one group, the ovaries were isolated in situ and the effects of a 15-min infusion of PGF-2 and PGE-2 infused into the ovarian bursa for 15 min. Intra-arterial infusion of 25,50,100 or 200ng PGF-2 /kg/min did not affect perfusion pressure; PGE-2 doses of 3·1, 6·2, 12·5 or 25 ng/kg/min caused reductions in proportion to the dose. All doses of PGF-2 (50·0, 100or 200 ng/kg/min) or PGE-2 (25, 50 or 100 ng/kg/min) increased blood flow in the ovarian stroma in proportion to the dose when administered by infusion into the ovarian bursa. There were no differences in the results from oestrous and anoestrous dogs. It is concluded that PGF-2 changes intraovarian blood distribution without interfering with the total blood flow while PGE-2 increases both the total and local ovarian blood flow.
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