Identifying ovarian tissue in the bitch using anti-Müllerian hormone (AMH) or luteinizing hormone (LH)

Half-life of serum anti-Müllerian hormone and changes after gonadectomy in adult female and male dogs with normal and abnormal gonads

Anti-Müllerian hormone (AMH) is a biomarker for the presence of gonadal tissue. Changes in serum AMH after gonadectomy are not well established, and its serum half-life is unknown in dogs. We measured serum AMH with a validated electro-chemiluminescent immunoassay in adult female (n = 12) and male (n = 7) dogs with normal gonads, as well as in dogs with gonadal pathology (ovarian remnant syndrome, ORS n = 3, testicular tumor [Leydig cell, Sertoli cell, seminoma] n = 3, unilateral abdominal cryptorchid n = 4) on the day of gonadectomy (D0), and on D3, D7, D14 (females and males), and D21, D28 (males only). Males had higher AMH concentrations than females independent of gonadal status (P < 0.001). Dogs with ORS had lower initial AMH (0.45 ± 0.43 ng/ml) than bitches with normal gonads (1.16 ± 0.44 ng/ml; P = 0.027). Cryptorchid dogs had higher initial concentrations (80.57 ± 52.81 ng/ml) than males with normal gonads (7.92 ± 2.45 ng/ml; P = 0.004), and those with testicular tumors (18.63 ± 5.04 ng/ml) were intermediate (P ≥ 0.250). AMH decreased over time (P ≤ 0.012) and was 0.01-0.04 ng/ml by D14 in females and 0.02-0.12 ng/ml by D28 in males. Serum half-life in the whole study population was 2.85 ± 0.51 days and did not differ between groups. In conclusion, serum AMH can differentiate between intact and gonadectomized status of adult dogs by 14 days after ovario(hyster)ectomy in females and by 28 days after surgical castration in males.

Abundance of Anti-Muellerian hormone in cat ovaries and correlation of its plasma concentration with animal age, weight and stage of the estrous cycle

In female animals of different species, Anti-Müllerian hormone (AMH) is produced by follicular granulosa cells and has been associated with the ovarian follicle pool. Because concentration of AMH in plasma of ovary-intact female cats is apparently more variable than previously assumed, we have analysed AMH concentration in blood of cats (n = 93) presented for routine ovariectomy and assessed ovarian histology and AMH protein expression in the surgically removed ovaries. We hypothesised that AMH is synthesized only in preantral and small antral follicles and that plasma AMH concentration reflects the antral follicle count (AFC). Corpora lutea were detected in 35% of the female cats, whereas plasma progesterone concentration was ≥1 ng/mL in 57% of the cats. Follicular cysts were present in 15 cats (16%). Positive immunostaining for AMH protein was detected in close to all primordial and antral follicles, ovarian cysts, 70% of corpora lutea and 28% of atretic follicles. Concentration of AMH in plasma averaged 6.8 ± 0.5 ng/mL (range 1.3-21.7 ng/mL). The AFC increased with increasing AMH concentration with a moderate positive correlation between AFC and AMH (r = 0.286, p < 0.01). Plasma AMH concentration was not affected by season or cats' age, weight, stage of the estrous cycle and presence of follicular cysts. In conclusion, AMH protein is expressed in all endocrine structures of the cat ovary. While AMH is a marker for the presence of ovarian tissue, its usefulness to assess ovarian function in individual female cats is of limited value.

Anti-Müllerian hormone levels in serum and testes of male dogs: relations with neuter status and bilateral abdominal cryptorchidism

Anti-Müllerian hormone (AMH) analysis has contributed to new information in the reproductive endocrinology of domestic animals, due to clinically available diagnostic tools. An accurate and rapid diagnostic method to distinguish between neutered and bilateral abdominal cryptorchid dogs is needed in veterinary practice. Therefore, this study uses an enzyme-linked immunosorbent assay to evaluate the clinical relevance of AMH analysis in peripheral blood as a diagnostic tool for dogs with suspected bilateral abdominal cryptorchidism. The possible alteration of the AMH localization in testicular tissue caused by this pathologic condition was also investigated using immunohistochemistry. Male dogs were divided into three groups of healthy intact (n = 14), healthy castrated (n = 14), and bilateral abdominal cryptorchid (n = 14) dogs. The results demonstrated a higher level of serum AMH in the cryptorchid group compared to the intact group (P < 0.01), while serum AMH levels of all castrated dogs were below the limit of detection (<0.05 ng/mL). Moreover, the percentage of positive AMH immunostaining of the intact group was less than that of the cryptorchid group (P < 0.01). A significantly positive correlation was found between serum AMH concentration and localization in testicular tissues (r = 0.93, P < 0.01). Our findings suggest that AMH levels in the peripheral blood could be used as an alternative and rapid screening method for detecting dogs with abdominal cryptorchidism.

Anti-Müllerian Hormone Concentrations for Determining Resumption of Sertoli Cell Function following Removal of a 4.7 mg Deslorelin Implant in Tomcats

Background: Deslorelin implant use in cats is a medical alternative to surgical sterilization, and due to its prolonged efficacy, its use has shown growing interest in the veterinary community. In the case of breeding facilities, its removal is often requested for the early restoration of testicular function. As anti-Müllerian hormones (AMH) in males is dependent of testosterone secretion, its assay may determine the restoration of testicular steroid secretion. An average of 3 weeks has been already described for tomcats' testicular function resumption after implant removal, but information about AMH concentrations in deslorelin-treated tomcats is lacking. Methods: Fourteen tomcats were treated for temporary suppression of fertility with a 4.7 mg deslorelin implant, which was surgically removed after 3, 6 or 9 months (n = 6, 4 and 4 tomcats, respectively). A general clinical and reproductive check with a gonadorelin stimulation test for testosterone determination was performed before deslorelin implant administration. After implant removal, tomcats' testicles were ultrasonographically checked for volume determination every 1-2 weeks with observation of the glans penis (presence or absence of spikes) and blood collection to assay both testosterone and AMH concentrations. Results: AMH concentrations increased significantly during the deslorelin treatment from 20.95 ± 4.97 ng/mL to 82.41 ± 14.59 ng/mL (p < 0.05). Following implant removal, AMH concentrations progressively decreased to pre-treatment levels, with a value of 28.42 ± 7.98 ng/mL on the third week post-removal where testosterone secretion was again detected. Conclusions: Even if a big variability of AMH concentrations exists between male individuals, resumption of tomcats' testicular function following a deslorelin treatment can be determined by AMH assay.

[Diagnostic utility of the anti-Mullerian hormone in companion animals]

The anti-Mullerian hormone is a glycoprotein secreted by Sertoli cells in males and granulosa cells in females. The initial identification of this hormone in canine and feline serum was achieved in 2011. Meanwhile, a variety of studies have demonstrated its clinical significance as a tool in the endocrine diagnosis. This review summarizes the current knowledge about anti-Mullerian hormone in small animal reproduction and describes future opportunities for its diagnostic usage.

Anti-Müllerian hormone concentrations in female rabbits and its relation to spay status, pseudopregnancy and ovarian follicle numbers

Anti-Müllerian hormone (AMH), known for its role during fetal sexual differentiation, is secreted by the Sertoli cells in males and the granulosa cells in females during postnatal life. As serum AMH concentrations correlate with follicle numbers, AMH is utilised as a marker of ovarian reserve in many species. In dogs and cats, AMH is used as a diagnostic tool to determine spay or neuter status. In the available literature, no research regarding serum AMH levels in rabbits has been published yet. The objectives of the present study were to 1) measure serum AMH concentrations in female rabbits and investigate the value of AMH as a diagnostic tool to differentiate between spayed and intact does, and 2) relate measured AMH levels to pseudopregnancy and ovarian follicle numbers. For AMH measurement, serum samples were obtained from sexually intact (n = 64) and spayed (n = 22) female rabbits. Spayed does were of various breeds; intact rabbits were Zika hybrid rabbits. In the intact does, AMH measurement was complemented by determination of progesterone levels, gynaecological examination, and histopathologic evaluation of the uterus and ovaries, including follicle counts. Serum AMH and progesterone concentrations were measured using a human-based chemiluminescence immunoassay (CLIA) and an enzyme-linked fluorescence assay (ELFA), respectively. Depending on progesterone levels, sexually intact does were classified into follicular (n = 52) or luteal phase (n = 12). Median serum AMH levels were 1.53 ng/ml (range 0.77 - 3.36 ng/ml) in intact and 0.06 ng/ml (range ≤ 0.01 - 0.23 ng/ml) in spayed does. AMH concentrations between the intact and spayed rabbits differed significantly and did not overlap (p < 0.001). Receiver operating characteristic (ROC) curve analysis yielded a sensitivity and specificity of 100% for a cut-off level of 0.50 ng/ml. Follicular or luteal phase had no significant influence on measured AMH levels (t = 0.061, df = 62, p = 0.951). While the number of secondary follicles correlated significantly with AMH concentrations (r_s = 0.410, p = 0.001), the number of primary or antral follicles did not (r_s = 0.241, p = 0.055 and r_s = 0.137, p = 0.281, respectively). In conclusion, a single determination of serum AMH concentrations was adequate to distinguish spayed from intact female rabbits. Among sexually intact individuals, whether does were in follicular or luteal phase had no significant influence on measured serum AMH concentrations. The relationship between small growing follicles and AMH levels as described in other species could be partially confirmed, as secondary follicles correlated significantly with AMH.

Clinical use of Anti-Müllerian Hormone to monitor resumption of ovarian activity following removal of a 4.7 mg deslorelin implant in queens

OBJECTIVE

The use of deslorelin implants to control reproduction in cats is increasing but because of its prolonged duration, cat breeders often request implant removal before the end of the treatment. Assaying Anti Mullerian Hormone (AMH) concentrations might be useful to predict time of resumption of ovarian activity in deslorelin-treated queens following implant removal. In queens a minimum of 3 weeks during increasing photoperiod after implant removal has been described for resumption of ovarian activity but no information about AMH concentrations were observed for determining ovarian activity.

ANIMALS

Sixteen queens in which deslorelin implants were surgically removed after 3, 6 or 9 months (n = 6, 4 and 6 queens, respectively) were used in this study.

PROCEDURES

A general and reproductive health check with a GnRH stimulation test were performed before the treatment. After implant removal queens were checked every 1-2 weeks with reproductive ultrasonography, a vaginal smear and blood collection to assay AMH concentrations.

RESULTS

AMH concentrations decreased significantly at the end of the treatment to ≤ 2.5 + 0.6 ng/ml (p ≤ 0.05) and reached a nadir at 1.9 ± 0.9 (p < 0.05) one-week post-removal. Following implant removal AMH concentrations started to rise reaching a value of 3.9 ± 0.7 ng/ml on the third week and were not different from pre-treatment levels on week 6 post-removal (5.8 ng/ml + 0.9, p ≥ 0.05). AMH values did not differ depending on duration of deslorelin treatment but were lower in adult queens (p < 0.05).

CLINICAL RELEVANCE

AMH assay can be a useful tool to follow resumption of feline ovarian function following a deslorelin treatment.

Serum anti-Müllerian hormone concentration as a diagnostic tool to identify testicular tissue in canine disorders of sexual development

Disorders of sexual development (DSD) may have their origin in alterations of the chromosomal, gonadal or phenotypic sex. Affected animals are usually presented because of ambiguous external genitalia, seldom because of reproductive disorders. Anti-Müllerian hormone (AMH) is secreted in the gonads with higher amounts in males than in females and can be used to identify gonadal tissue in sexually normally developed dogs. The aim of this study was to examine the diagnostic potential of serum AMH to identify testicular tissue in 11 dogs with DSD. The diagnostic procedures applied were: determination of the phenotypic sex (n = 11), genital ultrasound (n = 9), determination of the SRY gene (n = 11), karyogram (n = 6), gonadectomy (n = 11), pathohistology of the gonads (n = 10), serum AMH measurement (n = 11). 39 female dogs described in a previous study and 19 male dogs with a normal spermiogram served as controls for the AMH serum concentrations in sexually intact dogs. The 11 dogs with DSD were classified as 7 XY DSD and 4 XX DSD. Presumptive testes were obtained in 10 dogs and 1 dog had an ovotestis combined with a testis. Mean serum AMH values of the dogs with DSD were significantly higher (P < 0.001) than in male and female controls. The upper limit of the AMH test (≥ 23ng/ml) was reached in 6 dogs. High AMH concentrations have been described previously in cryptorchid dogs. 1 dog with a male phenotype and 2 with a female phenotype had AMH values within the range of the male controls, although all of them had cryptorchid testes. A Poodle, in which epididymis were identified but no definitive gonads, had an AMH concentration of the lower limit of the test (≤ 0.01 ng/ml), comparable to previously described castrated dogs. This study indicates that serum AMH levels are a useful diagnostic tool to identify testicular tissue in dogs with DSD and suggests the possible use of AMH to diagnose testicular dysgenesis.

Uptake of exogenous estrogen as a differential diagnosis of ovarian-remnant-syndrome in a bitch: a case report

Background

Clinical signs of heat in bitches that have been previously spayed are often associated with the presence of ovarian remnant syndrome. The inclusion of exogenous estrogens as a differential diagnosis in this regard is often ignored and may lead to misinterpretation of the case.

Case presentation

Herein, we report a case of exogenous estrogen exposure over several months to a 6.5-year-old spayed crossbred bitch, weighing 8.4 kg. The bitch presented in the clinic because of suspected ovarian remnant syndrome. Castration was performed within the first 6 months after birth. Important endocrine parameters measured at the first appointment were Anti-Müllerian hormone (< 0.01 ng/mL), progesterone (0.36 ng/mL), estradiol-17ß (20.7 pg/mL), and luteinizing hormone (< 0.1 ng/mL). After an extensive conversation with the owner, it was revealed that she was using an estrogen spray because of severe menopausal symptoms. After the owner stopped using this spray, the symptoms of the bitch disappeared.

Conclusion

Therefore, the uptake of estrogens should be a differential diagnosis for symptoms of the ovarian remnant syndrome. A detailed anamnesis is crucial to identify the source of estrogen in the environment of the affected bitch.

Comparison of a Point-of-Care Analyzer With a Chemiluminescent Immunoassay for Serum Progesterone Measurement in Breeding Management of the Bitch

Accurate serum progesterone measurements for timing bitches during breeding management is critical for reproductive practice, especially as artificial insemination has become routine to facilitate breeding of animals that are geographically or temporally separated. To measure serum progesterone, chemiluminescent immunoassay (CLIA) has replaced radioimmunoassay as the current standard in the bitch due to its high correlation and increased practicality. In January 2019, a colorimetric point-of-care (POC) immunoassay for quantitative in-clinic canine serum progesterone measurements in <30 min was released. This study provides an independent comparison of the POC (Catalyst One, IDEXX) to the current industry standard, CLIA (Immulite-2000, Siemens). To assess inter-assay imprecision of POC and agreement of the POC and CLIA results, 100 canine serum samples were analyzed on three analyzers (POC-1, POC-2, and CLIA), of which, 74 (POC-1) and 75 (POC-2) results were within POCs' reportable range of 0.2–20 ng/mL and included in the study. To assess intra-assay imprecision, pooled canine serum samples at low (L1), intermediate (L2), and high (L3) progesterone concentrations were analyzed ten times each on POC-1 and CLIA. Relative to CLIA, POC values showed good correlation (POC-1, r² = 0.9366; POC-2, r² = 0.9438, P < 0.0001) and significant positive proportional bias at values >2 ng/mL. The POC inter-assay coefficients of variation (CVs) were 13.2% (0.2–2.9 ng/mL, 0.6–9.2 nmol/L, L1), 10.0% (3.0–9.9 ng/mL, 9.5–31.5 nmol/L, L2), 7.1% (10.0–20.0 ng/mL, 31.8–63.6 nmol/L, L3), and 11.2% (all samples). The intra-assay CVs for POC (L1, 15.3%; L2, 7.0%; L3, 4.7%) were higher than those for CLIA (L1, 5.89%; L2, 4.89%; L3, 3.44%). Based on the more rapid increase in serial serum progesterone concentrations in ovulating bitches and the greater imprecision of the POC, the clinical interpretations of serum progesterone measurements as they relate to canine breeding management should be made with caution.

Anti-Müllerian hormone in dogs and cats reproduction

The anti-Müllerian hormone (AMH) is a glycoprotein secreted by Sertoli cells in males and granulosa cells in females. It has first been determined in blood serum of dogs and cats by Place et al. in 2011 with the use of a human-based ELISA test. Meanwhile, different immunoassays have been validated for AMH determination in animals and a variety of studies have demonstrated the clinical significance of AMH. This review summarizes the current knowledge about AMH in dogs and cats and describes future opportunities for its diagnostic use.

Investigation of interference from canine anti-mouse antibodies in hormone immunoassays

BACKGROUND

Canine anti-mouse antibodies are a potential source of immunoassay interference, but erroneous immunoassay results are not always easily identifiable. Anti-Müllerian hormone (AMH) is a marker for the presence of gonads in dogs, but elevated AMH concentrations in neutered dogs could also be caused by antibody interference. For other assays, a discrepant result obtained after antibody precipitation might indicate antibody interference.

OBJECTIVES

We aimed to evaluate if canine anti-mouse antibodies are a source of erroneous results in the AMH assay and if antibody precipitation with polyethylene glycol (PEG) is a useful tool for detecting antibody interference in a variety of immunoassays used in the veterinary clinical laboratory.

METHODS

Twenty-nine positive and 25 negative samples for anti-mouse antibodies were analyzed for AMH, canine total thyroxine (TT₄ ), canine thyroid-stimulating hormone (TSH) and progesterone before and after treatment with PEG. Results that differed by more than four SDs from the intra-assay coefficients of variation were considered discrepant. Elevated AMH concentrations in neutered dogs with anti-mouse antibodies and no visible gonads present were considered evidence of interference.

RESULTS

Evidence of antibody interference was found in two samples analyzed for AMH. The presence of anti-mouse antibodies did not lead to a higher proportion of discrepant results after PEG treatment for any of the immunoassays. The overall incidence of discrepant results for healthy controls was very high (73%).

CONCLUSIONS

Canine anti-mouse antibodies are a source of erroneous AMH results. Antibody precipitation with PEG is not a useful tool for detecting interference caused by such antibodies.

Field study assessing the performance of a patient-side blood test to determine neuter status in female cats based on detection of luteinising hormone

OBJECTIVES

The aim of this study was to assess the performance of a patient-side blood test in determining neuter status in female cats.

METHODS

Residual blood samples from female cats of unknown neuter status that were admitted to four cat adoption centres in the UK were tested for luteinising hormone (LH) using the Witness LH test (Zoetis). A positive LH test result indicated that the cat was neutered. Cats were assessed for evidence of a surgical scar suggestive of prior neutering; if none was found, an exploratory laparotomy was performed to confirm neuter status. The LH test performance was assessed (sensitivity, specificity, negative and positive predictive value).

RESULTS

Two hundred and thirty-six cats had both LH test and exploratory laparotomy data. The specificity of the test in detecting neutered cats was 100% (95% confidence interval 96.2-99.9) and the sensitivity was 69% (95% confidence interval 59.3-76.8). The prevalence of neutered cats in this sample was 49%. The positive and negative predictive values were 1 and 0.77, respectively.

CONCLUSIONS AND RELEVANCE

The Witness LH test correctly detected all unneutered cats and thus there were no false-positive results that incorrectly indicated a cat was neutered. This study therefore suggests that positive LH test results avoid the need to perform surgery to confirm neuter status. This has significant welfare benefits for cats as it provides a lower risk, faster and less traumatic alternative to surgery and, in the shelter setting, it will have a positive impact on the cost, speed of assessment and time to rehoming of cats.

A comprehensive study of disorder of sex development in Staffordshire bull terrier dog

An 8-month-old female Staffordshire bull terrier was clinically examined because of external sexual organs abnormality-clitoral hypertrophy. As stated by the owner, the female dog had not been in heat yet. Serum profile of testosterone (3.39 ng/ml), as well as an anti-Műllerian hormone (24.0 ng/ml), suggested the presence of testicular tissue. On the contrary, the estimated level of 17β-oestradiol (24.6 pg/ml) was approximately two times higher when compared with the normal anoestrus values (5-10 pg/ml). A midline laparotomy was performed to detect the cranial parts of the genital system. Gonads resembling testicle or ovotestis (left) and hypoplastic testicle (right) was visible. Cranial portion of gonads was attached to structures indicative of bilateral epididymidis. The next tubular structures-oviducts were resected along with adherent parts of a hypoplastic uterus. Histological evaluation confirmed that the examined gonad samples were testicles with modified interstitial testicular tissue. Hypertrophy of interstitial space was predominantly formed by Leydig cells. Examination of a cross-section through the head of suspected epididymidis confirmed their characteristic structures. In addition, the characteristic configuration of the oviducts was presented. The uterus consisted of three walls, in which the endometrium was hypoplastic with the presence of endometrial glands. No Y chromosome was detected by chromosomal analysis using CFA Y probe and the amplification of SRY-gene coding region (813 bp) indicated genotype 78, XX; SRY-negative. Sequencing of SOX9 gene exons 1-3 did not reveal any differences in exon 1 and 3. On the contrary, a few changes were determined in the SOX9 exon 2 sequences: G instead of A at position 103; C instead of reference T at position 115; GCG instead of reference CGC at position 138-140; T instead of reference C at positions 161, 164 and 167.

Changes in anti-Müllerian hormone concentrations in bitches throughout the oestrous cycle

Studies in female dogs proved the measurement of anti-Müllerian hormone (AMH) as a diagnostic tool to distinguish ovarioectomized from intact females or to diagnose ovarian remnant syndrome. Furthermore, its usability to diagnose a granulosa cell tumour and predict litter size was also investigated in female dogs. Although serum AMH was previously shown to increase during the transition from anoestrus to pro-oestrus in dogs, changes in AMH concentration over the entire oestrous cycle have not yet been determined. The aim of this study was to investigate the secretion pattern of AMH throughout the oestrous cycle in non-pregnant bitches. As a preliminary step, we tested our assay by measuring AMH concentrations in serum samples of 19 intact bitches (10 in anoestrus, 3 in pro-oestrus, 3 in oestrus, 3 in metoestrus) and 19 spayed females of different age and breed. For the main study, 20 healthy female dogs were examined (10 Beagles, and 10 Labrador crossbreeds, body weight 10-28 kg, age 1-6 years) during a normal oestrous cycle. Serum samples were collected in late anoestrus, at several times during pro-oestrus and oestrus, as well as 28 days and 4.5 months after ovulation. Blood collection was combined with a gynaecological examination including progesterone measurement. Serum concentration of AMH was determined using a chemiluminescence immunoassay validated for dog serum. In the preliminary test, intact bitches in various stages of the oestrous cycle had significantly higher serum AMH levels (0.19-1.45 ng/ml) than spayed females (0.01-0.06 ng/ml, P < 0.001). In cycling Beagle and Labrador crossbreed bitches participating in our main study, AMH concentrations were between 0.09 and 2.65 ng/ml with higher AMH concentrations in Beagles but overall high inter-individual and intra-individual variation. The highest AMH values were reached in the last three weeks before the onset of heat until six days before ovulation, and the lowest AMH concentrations were recorded during preovulatory oestrus in 6, metoestrus in 7 or anoestrus in 7 dogs. Serum AMH concentrations increased significantly from late anoestrus up to six days before ovulation and decreased significantly over the last three days before ovulation. A further significant decrease occurred from the last days of oestrus to metoestrus and mid anoestrus. This study shows that the used AMH assay can clearly distinguish between intact and spayed females and that the serum AMH pattern over the oestrous cycle is similar in all bitches, but with high variation among the breeds and among and within bitches. These changes in the AMH concentration are a challenge in timing serum sample collection and interpreting AMH values in bitches. Further studies are necessary to emphasize the factors influencing the AMH concentration.