Comparative quantitative assessment of GnRH- and LH-receptor mRNA expression in the urinary tract of sexually intact and spayed female dogs

Chronic Use of Deslorelin in Dogs: Six Cases (2005-2022)

Deslorelin is currently registered for the induction of temporary infertility in male dogs, male cats, male ferrets, and also prepubertal female dogs, but research has shown its usefulness for other conditions requiring chronic treatment. This paper presents six cases of dogs chronically treated with deslorelin for indications such as benign prostatic hyperplasia, control of fertility, abnormal reproductive behavior and urinary incontinence. All animals were in good health during treatment. Treatment duration was 2-9 years. No short-term side effects were observed except for flare-up reactions, which were observed only in 1/4 intact males. Two dogs developed a neoplasia: a spayed bitch treated for urinary incontinence developed a pituitary carcinoma, and an intact male dog implanted for control of fertility developed a bladder carcinoma. While the pituitary carcinoma seems unlikely to be related to deslorelin, the bladder carcinoma could be due to the neutered condition of the dog (which was treated for 9 years) as urinary tract neoplasia is more common in dogs following gonadectomy. Chronic treatment with deslorelin is regarded as safe when an animal is being treated for life. The possibility that a pause in the treatment might be helpful for the animal should be investigated.

Long-term effect of repeated deslorelin acetate treatment in bitches for reproduction control

Long-acting gonadotropin-releasing hormone (GnRH) analogs, which are approved for male dogs and ferrets, have been used off-label to suppress estrus in bitches predisposed to the side effects of spaying. Health data from the past 12 years were evaluated from bitches without progestogen pretreatment that received deslorelin acetate (DA) to suppress estrus for the first time before the age of 4.5 years. The study population included 32 client-owned bitches repeatedly treated with either 4.7 mg or 9.4 mg DA implants for a period of 5.3 ± 3.4 years (range 0.5-11.3 years). Follow-up information concerning immediate side effects of DA occurring within five months after the first DA treatment (n = 23) as well as long-term side effects of sustained gonadal suppression occurring after five months up to three years (n = 2), three years up to five years (n = 2) or more than five years (n = 8) were assessed through a questionnaire. Treatment was considered successful if no major side effects requiring medical treatment occurred, which applied to 26 out of 32 (81 %) bitches. In the six remaining bitches, the following major side effects led to treatment discontinuation: persistent urinary incontinence (n = 1), reoccurring induced heat (n = 1), uterine disease (n = 3) and/or ovarian tumor (n = 3). The bitches recovered completely after surgical spaying and/or DA implant removal. Minor side effects that did not require therapy or affect animal welfare included body weight changes (n = 18), subtle behavioral changes (n = 13), induced heat (n = 12), coat changes (n = 11), pseudocyesis (n = 6), transient urinary incontinence (n = 4), and/or temporary thickening of the uterine wall with little anechogenic content (n = 2). To examine a possible causal relationship between adverse side effects and DA treatment, further studies should compare the frequency of pathologies between groups of GnRH-treated, intact and spayed bitches of similar breeds and ages. Nevertheless, DA application before the age of 4.5 years may be a means of postponing surgical spaying for several years in breeds at high risk for developing urinary incontinence. Before DA is used in bitches, owners should be fully informed regarding possible side effects.

A Mapping Study of Veterinary Literature on Perceptions and Attitudes of Female Canine Spaying

This is a mapping study conducted to evaluate the characteristics of where content that engages in perspectives or attitudes on female dog spaying is published. Three databases, CAB Direct, PubMed, and Scopus, were systematically searched. There were 84 out of 642 papers identified and screened for relevance on attitudes or perceptions on female canine spaying. These 84 articles were then examined for recurring authors, institutional representation, and publisher information. Additionally, information regarding the population being addressed, veterinarian or client, was noted with most literature addressing the veterinary perspective. Many important articles were published in a wide array of journals from many countries, which suggests the importance of not only browsing journals but also searching for relevant literature in databases like CAB Abstracts and MEDLINE.

Do prevalence rates and severity of acquired urinary incontinence differ between dogs spayed by laparoscopy or laparotomy? Comparing apples with apples with a matched-pair cohort study

OBJECTIVE

To compare the prevalence rates and severity of acquired urinary incontinence (AUI) between dogs spayed with laparoscopic and open laparotomy approaches.

STUDY DESIGN

Retrospective matched-pair cohort study.

ANIMALS

In total, 1285 privately owned dogs spayed >5 years previously were included in the study.

METHODS

Laparoscopically spayed dogs were matched with dogs spayed by traditional laparotomy. Matching variables were breed, bodyweight, age at spaying, time of spaying in relation to the onset of puberty, time interval since spaying, and age. In 400 matched-paired dogs, the outcome of AUI was assessed by using an owner questionnaire. A conditional logistic regression for matched pairs was performed on the data of 308 dogs.

RESULTS

Among 308 dogs, 30 and 29 dogs spayed by laparotomy and laparoscopy, respectively, were affected by AUI. The identified risk factors for AUI were age and time interval since spaying. The surgical approach (laparoscopy or laparotomy) was neither revealed as a risk factor nor did it influence the severity of AUI.

CONCLUSION

The risk of AUI after spaying is not influenced by the surgical approach, (laparoscopy or laparotomy). Nearly every fifth dog spayed by laparotomy or by laparoscopy was affected by AUI. A relatively longer time interval since spaying and increased age of the dog increased the risk for AUI.

CLINICAL SIGNIFICANCE

Owners of dogs with a predisposition for AUI must be counseled about this risk when they present their dogs for spaying, regardless of surgical approach chosen.

Kastration der Hündin – neue und alte Erkenntnisse zu Vor- und Nachteilen

Die Beratung von Hundehaltern bezüglich der Vorteile und Nachteile sowie des optimalen Zeitpunktes der Kastration einer Hündin ist komplex und sollte sich auf verlässliche Daten aus der Wissenschaft stützen sowie individuelle Belange berücksichtigen. Bei genauerer Betrachtung der aktuellen Publikationen zu diesem Thema fällt auf, dass einige lange für robust gehaltene Informationen etwas angepasst oder aktualisiert werden müssen. Ein offensichtlicher Vorteil der elektiven Kastration ist, dass Erkrankungen der Ovarien und sexualsteroidabhängige Erkrankungen wie Metropathien nicht auftreten. Weiterhin ist ein gewisser protektiver Effekt einer frühzeitigen Kastration auf die Entstehung von Mammatumoren anzunehmen, wenngleich dafür derzeit eine schwache wissenschaftliche Evidenz besteht und der Effekt vermutlich geringer ausfällt, als in einigen älteren Publikationen angegeben wurde. Die Kastration hat jedoch auch Nachteile. Als häufigste negative Folge wird seit Jahrzehnten die Harninkontinenz beschrieben. Aussagen zur Inzidenz sowie zu weiteren Einflussfaktoren, wie Kastrationszeitpunkt in Bezug zur Pubertät, sind jedoch uneinheitlich. Aktuell werden vor allem das gehäufte Auftreten verschiedener Tumorerkrankungen, die nicht direkt mit dem Reproduktionstrakt in Verbindung stehen, sowie ein höheres Risiko für Erkrankungen des Bewegungsapparats bei kastrierten Tieren diskutiert. Weitere Einflussfaktoren wie der Ernährungszustand des Hundes, Alter und/oder Haltung wurden jedoch häufig nicht erfasst. Die Datenlage zur Auswirkung der Kastration auf den Stoffwechsel und das Immunsystem der Hündin ist derzeit ungenügend. Wünscht der Tierbesitzer eine Kastration, bedarf es in jedem Fall einer eingehenden Beratung, die individuelle, rasse- und haltungsbezogene Aspekte einschließt. Derzeit ist eine Kastration am ehesten zwischen der ersten und zweiten Läufigkeit zu empfehlen, da ein gewisser protektiver Effekt auf die Entstehung von Mammatumoren anzunehmen ist und das Risiko unerwünschter Nebenwirkungen nach heutigem Wissensstand moderat ausfällt.

High luteinizing hormone weakens urinary continence mechanisms in association with prostaglandin E2 elevation in a postmenopausal rat model

AIMS

To explore the role of luteinizing hormone (LH) in the urinary continence mechanism, urethral function was investigated using a postmenopausal rat model with high serum LH concentrations and the postmenopausal rat model given a gonadotropin releasing hormone (GnRH) antagonist to lower LH concentrations.

METHODS

Adult female rats were divided into: 1) sham group; 2) ovariectomy group (OVX) with removal of bilateral ovaries; 3) OVX and GnRH-antagonist administered group (OVX + G); and 4) sham and GnRH-antagonist administered group (Sham + G). Urethral function was evaluated by the sneeze-induced urethral continence reflex experiment, and serum LH and prostaglandin E2 (PGE2) concentrations were measured.

RESULTS

In the sneeze-induced urethral continence reflex experiment, urethral baseline pressure (UBP) and the amplitude of the urethral response during sneezing (A-URS) were measured. The UBP was significantly decreased in the OVX group than in the other groups. A-URS was significantly lower in the OVX group than in the Sham group, but with no significant difference compared with the OVX + G group. Lowering the serum LH by a GnRH-antagonist improved UBP to the same level as in the Sham group. The serum PGE2 concentration was significantly higher in the OVX group than in the other groups.

CONCLUSIONS

The results suggested that the increased serum LH concentration in the OVX rat model worsened the continence mechanism. This mechanism is probably associated with an increased PGE2 concentration, because PGE2 caused urethral smooth muscle relaxation. A GnRH-antagonist might improve urinary incontinence by decreasing the serum LH and PGE2 concentrations.

Therapeutic Potential of Human Chorionic Gonadotropin Against Overactive Bladder

Overactive bladder (OAB) is a common form of urinary incontinence, resulting from spontaneous and random contractions of the urinary bladder. The affected individuals have an uncontrollable urge to urinate and experience incontinence and nocturia, which can greatly reduce the quality of daily life. There are several drugs for the treatment, and all of them have serious side effects. The following findings suggested that human chorionic gonadotropin (hCG) has a therapeutic potential that is worth investigating for the treatment of OAB. The finding are (1) human detrusor muscle contains hCG receptors, (2) detrusor muscle becomes quiescent during pregnancy, (3) hCG can inhibit detrusor muscle contractions induced by cholinergic stimulation in rats, and (4) hCG can mimic the anticholinergic drug on detrusor muscle contractions.

Urinary incontinence in the bitch: an update

Urinary incontinence (UI), defined as the involuntary loss of urine during the filling phase of the bladder (Abrams et al. 2002), is a commonly seen problem in veterinary practice. Urinary sphincter mechanism incompetence (USMI) after spaying is the most common micturition disorder, and its medical treatment is normally successful, even though the underlying pathophysiological mechanism is not fully understood. Hormonal changes inducing structural and functional alterations in the bladder, as well as in the urethra composition, are discussed. To manage incontinent patients successfully, possible underlying abnormalities besides USMI should be ruled out. In the majority of cases, history, physical examination and simple tests including urinalysis and urine bacterial culture lead to a presumed aetiology. If USMI is the most likely cause, then the advantage of further diagnostic tests should be discussed with the owner before starting a trial therapy with alpha-adrenergic drugs. Potential side effects of this therapy have to be mentioned even though they rarely occur. It is important to thoroughly evaluate the success of the initial treatment. Its failure should lead to further diagnostic testing. Specialized clinical assessments may provide an aetiological diagnosis, and this could serve as a basis for discussing further treatment options. Surgical procedures, which may in rare cases cause irreversible side effects, may be instituted. If incontinence reoccurs after initial treatment was successfully performed, the diagnostic work-up including urinalysis should always be repeated. As results of urinalysis did not correlate well with results of bacterial culture, a urine culture is recommended (Comer and Ling 1981). Cystocentesis is the preferred method of urine collection (Bartges 2004). Equivocal results of quantitative cultures of urine samples obtained during midstream voiding or by catheterization require repeat collection by cystocentesis (Comer and Ling 1981).

Molecular cloning, sequencing, and distribution of feline GnRH receptor (GnRHR) and resequencing of canine GnRHR

GnRH receptors play vital roles in mammalian reproduction via regulation of gonadotropin secretion, which is essential for gametogenesis and production of gonadal steroids. GnRH receptors for more than 20 mammalian species have been sequenced, including human, mouse, and dog. This study reports the molecular cloning and sequencing of GnRH receptor (GnRHR) cDNA from the pituitary gland of the domestic cat, an important species in biomedical research. Feline GnRHR cDNA is composed of 981 nucleotides and encodes a 327 amino acid protein. Unlike the majority of mammalian species sequenced so far, but similar to canine GnRHR, feline GnRHR protein lacks asparagine in position three of the extracellular domain of the protein. At the amino acid level, feline GnRHR exhibits 95.1% identity with canine, 93.8% with human, and 88.9% with mouse GnRHR. Comparative sequence analysis of GnRHRs for multiple mammalian species led to resequencing of canine GnRHR, which differed from that previously published by a single base change that translates to a different amino acid in position 193. This single base change was confirmed in dogs of multiple breeds. Reverse transcriptase PCR analysis of GnRHR messenger RNA in different tissues from four normal cats indicated the presence of amplicons of varying lengths, including full-length as well as shortened GnRHR amplicons, pointing to the existence of truncated GnRHR transcripts in the domestic cat. This study is the first insight into molecular composition and expression of feline GnRHR and promotes better understanding of receptor organization, and distribution in various tissues of this species.

Gonadotropin-releasing hormone immunization for the treatment of urethral sphincter mechanism incompetence in ovariectomized bitches

We have investigated GnRH immunization for the treatment of urethral sphincter mechanism incompetence in ovariectomized bitches. It has been reported that decreasing LH secretion through the use of GnRH agonists temporarily restores continence in some bitches. Therefore, decreasing the circulating LH concentrations by immunizing against GnRH might temporarily maintain continence in incontinent dogs. Sixteen incontinent dogs given phenylpropanolamine (PPA) to control incontinence were recruited for this study. Eleven dogs were immunized against GnRH (novel treatment group) at week 0, and nine dogs were vaccinated again 4 weeks later. Five dogs (standard treatment group) were vaccinated with a placebo twice at 4-week intervals. PPA was discontinued in the novel treatment group 2 weeks after revaccination, and standard-treatment dogs were given PPA for the duration of the study. Blood samples were collected before each treatment and at 6, 8, 10, 12, 16, 20, and 24 weeks and owners recorded episodes of incontinence throughout the study. Ten of the eleven dogs in the novel treatment group experienced side effects as a result of vaccination; two of these dogs experienced more severe side effects after the first vaccination and were withdrawn from the study as a result. Of the nine dogs that completed the vaccination series, four dogs remained continent after PPA was discontinued. For these four dogs, there was no difference in incontinent episodes when they were given PPA versus treatment with the vaccine. All nine novel-treatment dogs developed a GnRH antibody titer and experienced a significant decrease in circulating LH concentrations. In conclusion, GnRH immunization was effective in maintaining continence in four of the nine incontinent ovariectomized dogs, and in these dogs, treatment with the vaccine was comparable with treatment with PPA.

The heart: a novel gonadotrophin-releasing hormone target

Gonadotrophin-releasing hormone (GnRH) is a hypothalamic hormone transported by the hypophyseal portal bloodstream to the pituitary gland, where it binds to GnRH receptors. However, GnRH receptors are expressed in multiple extrapituitary tissues, although their physiological relevance is not fully understood. GnRH agonists are employed extensively in steroid deprivation therapy, especially to suppress testosterone in prostate cancer. Because GnRH agonist treatment is associated with increased coronary heart disease and myocardial infarction, we investigated the impact of GnRH on cardiomyocyte contractile function. Cardiomyocytes were isolated from mouse hearts and mechanical and intracellular Ca(2+) properties were evaluated, including peak shortening amplitude (PS), time-to-PS (TPS), time-to-90% relengthening (TR(90) ), maximal velocity of shortening/relengthening (± dLdt), electrically-stimulated rise in Fura-2 fluorescence intensity (ΔFFI) and Ca(2+) decay. GnRH (1 ng/ml) increased PS, ± dL/dt, resting FFI and ΔFFI, and prolonged TPS, TR(90) and Ca(2+) decay time, whereas 1 pg/ml GnRH affected all these cardiomyocyte variables, except TPS, resting FFI and ΔFFI. A concentration of 1 fg/ml GnRH and the GnRH cleavage product, GnRH-[1-5] (300 pg/ml), had no effect on any cardiomyocyte parameter. The 1 pg/ml GnRH-elicited responses were attenuated by the GnRH receptor antagonist cetrorelix (10 μm), the protein kinase A (PKA) inhibitor H89 (1 μm) but not the protein kinase C inhibitor chelerythrine chloride (1 μm). These data revealed that GnRH is capable of regulating cardiac contractile function via a GnRH receptor/PKA-dependent mechanism. If present in the human heart, dysfunction of such a system may play an important role in cardiac pathology observed in men treated with GnRH agonists for prostate cancer.

Effects of the gonadotropin-releasing hormone antagonist ganirelix on normal micturition and prostaglandin E(2)-induced detrusor overactivity in conscious female rats

BACKGROUND

Gonadotropin-releasing hormone (GnRH) antagonists have been reported to have beneficial effects on lower urinary tract symptoms in patients with benign prostatic hyperplasia.

OBJECTIVE

Our aim was to investigate the effects of ganirelix, a GnRH receptor antagonist, on bladder function and detrusor overactivity (DO) in female rats.

DESIGN, SETTING, AND PARTICIPANTS

Female Sprague-Dawley rats received 2 wk of daily systemic (0.1 mg/kg) or acute intravesical administration (IVES; 0.14 mg/l or 1.4 mg/l) ganirelix or vehicle (controls).

MEASUREMENTS

Assessments were obtained using cystometry in awake rats, organ bath studies, enzyme-linked immunosorbent assay, and western blot (WB).

RESULTS AND LIMITATIONS

Luteinising hormone levels were lower in rats treated systemically with ganirelix than in controls. No differences were observed in body or bladder weights. Micturition interval (MI), micturition volume (MV), residual volume, and bladder capacity (BC) were similar in both groups at baseline. No differences in urodynamic pressure parameters were observed between groups at baseline. Intravesical prostaglandin E(2) reduced MI, MV, and BC, and it increased basal pressure (BP), threshold pressure (TP), flow pressure (FP), and maximum pressure (MP) in all rats. MI, MV, and BC were reduced by 43%±4%, 50%±4%, and 43%±4% (controls) versus 22%±3%, 23%±3%, and 21%±3% (ganirelix-treated rats; p<0.001). TP and FP increased by 38%±8% and 30%±4% (controls) versus 16%±7% and 16%±5% (ganirelix; p<0.05). The maximal force of contractions for carbachol was larger in detrusor from ganirelix-treated rats (231% vs 177% of 60 mM K+-induced contractions). At 0.14 mg/l, but not 0.14 mg/l, IVES ganirelix increased MI, MV, and BC and decreased BP, TP, FP, and MP. In vitro, ganirelix had no effect on detrusor function. The gonadotropin-releasing hormone receptor was expressed (by WB) in the bladder mucosa.

CONCLUSIONS

Systemic treatment with ganirelix counteracted experimental DO in female rats. Because bladder preparations from these rats exhibited larger contractions to carbachol and because intravesical ganirelix affected both micturition intervals and urodynamic pressure profiles, a peripheral site of action of ganirelix in the urinary bladder cannot be excluded.

Effects of gonadotrophin-releasing hormone outside the hypothalamic-pituitary-reproductive axis

Gonadotrophin-releasing hormone (GnRH) is a hypothalamic decapeptide with an undisputed role as a primary regulator of gonadal function. It exerts this regulation by controlling the release of gonadotrophins. However, it is becoming apparent that GnRH may have a variety of other vital roles in normal physiology. A reconsideration of the potential widespread action that this traditional reproductive hormone exerts may lead to the generation of novel therapies and provide insight into seemingly incongruent outcomes from current treatments using GnRH analogues to combat diseases such as prostate cancer.

Differences in the expression of luteinizing hormone and follicle-stimulating hormone receptors in the lower urinary tract between intact and gonadectomised male and female dogs

Receptors for LH (LHR) and FSH (FSHR) are expressed in the canine lower urinary tract (LUT). As gonadectomy results in an increase in plasma LH and FSH, the objective of this study was to determine whether there are any differences in the expression of LHR and FSHR in the LUT between intact and gonadectomised dogs. Four regions of the LUT, i.e. body and neck of the bladder as well as proximal and distal urethra, were collected from 20 healthy dogs (5 intact males, 5 intact anoestrous females, 4 castrated males and 6 spayed females). The mRNA and protein expression of receptors was determined by in situ hybridization and immunohistochemistry, respectively, and assessed semi-quantitatively incorporating both the distribution and the intensity of specific staining. Expression of LHR and FSHR was present in all tissue layers (epithelium, sub-epithelial stroma and muscle) of each region with different levels of the expression. Overall mRNA and protein expression for both LHR and FSHR was significantly (P<0.001) lower in gonadectomised dogs. Intact dogs had more (P<0.05) LHR and FSHR mRNA and protein in all tissue layers of the four regions, except for LHR mRNA expression in the sub-epithelial stroma where no differences were observed between the two statuses. Decreases in LHR and FSHR mRNA and protein in gonadectomised dogs appeared to be more consistent in spayed bitches compared to castrated males. Lower expression of LHR and FSHR observed in gonadectomised dogs may adversely affect the normal canine LUT function.