Safe and effective use of the oral bihormonal drug for the long-term regulation of reproductive function in home cats

For citation: Zeinalov O. A., Belova E. E, Mukaseev S.V., Beloglazov D.V., Safe and effective use of the bihormonal drug for the oral long-term regulation of reproductive function in home cats, Russian veterinary journal (Rossijskij veterinarnyj zhurnal), 2020, No. 1, pp. DOI:

UDK 619: 616.995.1: 615

Keywords: safety, efficacy, bi-hormonal contraceptive drug, SEX BARRIER®, cats.

The article presents the results of monitoring the safety of prolonged use of the oral bihormonal contraceptive drug SEX BARRIER® for delaying and interrupting estrus in home cats by their owners. The use of the bihormonal contraceptive preparation SEX BARRIER® in the home cats by the owners does not lead to disturbances in the genital area, clinical status, morphological and biochemical parameters of animals blood. All owners have confirmed the 100 % effectiveness of the bi-hormonal preparation SEX BARRIER® for both interruption and delay of estrus.

Abbreviations: BB — blood biochemistry, AS – active substance, P3-EDTA – ethylenediaminetetraacetic acid tripotassium salt, SDA – small domestic animals, BW — body weight, CBC — complete blood count, US — ultrasound investigation.

Introduction

Currently, a steady tendency towards increase in the number of domestic cats and dogs is observed in Moscow, St. Petersburg and other cities with millions of residents. Pet owners have developed a need for more humane treatment of their pets, which makes it necessary to constantly improve the level of literacy in terms of feeding, housing, care and veterinary services. In this regard, the issues related to the regulation of undesirable sexual behavior of domestic meat-eaters, especially cats [1...3, 9], are still relevant. It should be noted that natural cyclic manifestations of the functioning of the reproductive system in domestic female cats create significant inconvenience for the owners and reduce not only the pleasure of communicating with the pet, but the quality of life of family members as well.

At the same time, it should be taken into consideration that the radical method of surgical castration of female cats does not guarantee 100% result for suppressing undesirable manifestations of heat, both behavioral and physiological [4], and it irreversibly affects the endocrine system of the animal. Currently, conservative methods of managing reproductive behavior in SDA have been developed and are widely used. These methods are based on the use of oral hormonal contraceptives [1...3].

Domestic veterinary market offers the owners two groups of oral hormonal contraceptives that differ in their qualitative and quantitative composition. The drugs of the first group were implemented in the veterinary practice in the last quarter of the last century and are registered in different countries. As an active substance, they contain a single hormone (in most cases, megestrol acetate, which is a synthetic analog of progesterone), therefore, they are classified as mono-hormonal contraceptives. A serious disadvantage of this group of drugs consists in the need to use large single and course doses of the AS to suppress behavioral manifestations of the heat, which is not safe in the long terms since it can lead to the development of a complex of cystic endometrial hyperplasia and pyometra [10], mammary gland fibroadenomatosis [11...13], as well as to clinical and pathological changes typical for diabetes mellitus [14...16].

It is clear that this limits and complicates the use of mono-hormonal contraceptives in cats and dogs. The second group contains bi-hormonal oral contraceptive drugs. They have been developed and registered in the Russian Federation and have been used in the veterinary practice in small domestic animals for the past 20 years. These are gestagen-estrogen compositions in which gestagen is represented by a synthetic analog of progesterone (mepregenol ether), and estrogen is represented by a synthetic analog of estradiol (ethinylestradiol). Bi-hormonal compositions are developed taking into account the principles applied in the modern human medicine, and are focused on the doses of gestagen and estrogen, which provide the necessary balance between the efficacy, safety and proper control of the sexual cycle. This approach is crucial in development of this type of drugs, since they must meet the safety requirements for the long-term hormone therapy [5]. A 20-year practice of using bi-hormonal contraceptives have demonstrated that their effect on the animal body, in contrast to castration, is reversible, with restoration of sexual cyclicity in SDA occurring in a fairly short time – in 2...3 months after discontinuation of the drug [8].

Recently, we have published data from a comprehensive experimental study investigating the effect of more than two years of continuous use of the oral bi-hormonal drug SEX BARRIER® (LLC Research and Production Company SKiFF, Moscow) on female cats, which was conducted in a clinic (BIO-VET, Moscow). They clearly suggest that according to the results of clinical, laboratory and instrumental diagnostics, no deviations from the physiological normal range were detected in all animals receiving the drug during the entire experiment [6]. There is every reason to believe that the obtained result is achieved due to the correct combination of gestagen with estrogen in the drug thus allowing to significantly reduce the dosage of the gestagen component (table 1), and with proper use of the bi-hormonal drug to avoid the development of adverse reactions in the genital and extragenital system of the animal's body, at the same time physiologically regulating estrous behavior.

Objective of the study

To determine the safety and efficacy of the drug for a long-term use at home in female cats from different age groups. This paper presents the results of the monitoring of a long-term use of the oral bi-hormonal contraceptive drug SEX BARRIER® for delaying and interrupting estrus in female cats by their owners at home. It was conducted simultaneously with the study conducted on the basis of the veterinary clinic [6] and the possibility of certain deviations from the recommendations stated in the instructions for the drug’s use could not be ruled out [8].

Materials and methods

The study was conducted from April 2016 till September 2018 on female cats kept at home, the condition of which was monitored at certain intervals by specialists of the veterinary clinic BIOVET (Moscow) under the supervision of the Head of the Department of Laboratory Diagnostics, Doctor of Veterinary Sciences E. E. Belova.

Criteria for enrolling the animals in the study

Based on the results of selection by the recruiting agency during April-May 2016, 30 intact female cats aged from 1 to 14 years old, with BW = 3.2...4.3 kg, were enrolled in the experiment, whose owners live in Moscow and during the animal’s life, with varying extent of regularity, use the bi-hormonal contraceptive drug SEX BARRIER® in drops according to the regimen for interrupting and delaying estrus. During the experiment, the animals were kept in regular conditions, which, according to the data obtained as a result of the preliminary survey of the owners, were different. In addition to information about the type of housing (home-kept animal or conditions with outdoor walking, type and area of housing, number of the family members) and feeding (ready-made menus, natural or mixed type of feeding), attention was paid to the information about the presence of certain chronic diseases in the animal.

Animal distribution in groups. All animals were divided into three groups according to the age and BW. The first group included 10 female cats aged from 1 to 5 years old, the second group included 10 female cats aged from 5 to 10 years old, and the third group included 10 female cats aged from 10 to 14 years old. The control arm of intact female cats (n = 10) aged from 2 to 5 years old, whose owners never used or are not using hormonal drugs for correction of sexual behavior, was also created.

The drug. Each female cat owner from the experimental groups was provided with a bihormonal contraceptive drug SEX BARRIER®, drops for female cats, in the required amount determined by the instructions for use. Active substances of the drug include a synthetic gestagen mepregenol acetate, water soluble, and estrogen ethinylestradiol. One ml of the drug contains 1 mg of water-soluble mepregenol acetate and 0.01 mg ethinylestradiol. According to the degree of impact on the body, the drug belongs to low-hazard substances (hazard class IV according to GOST 12.1.007-76) [7].

Mode of the experiment. All animals before the experiment were subjected to the clinical investigation in the veterinary clinic BIO-VET (Moscow), which included registration of age, breed, BW, general examination, assessment of the condition of the skin and fur coating, ears, teeth and oral mucosa, thermometry, examination of the external genitals, as well as palpation of the mammary glands. In addition to the above-mentioned manipulations, blood was drawn for CBC and BB testing; ultrasound examination of the uterus and ovaries was performed. The received data was entered into the individual registration cards. The changes in progesterone and estradiol concentrations over time were not determined due to the inability to create controlled conditions for keeping and feeding the animals included in the study. CBC and BB in cats of experimental and control groups were analyzed in the laboratory of the veterinary clinic BIOVET. For CBC, blood was drawn from the vein in the fasted condition in a vacuum tube with P3-EDTA in an amount of at least 1.0 ml and was tested on an automatic hematological analyzer HESKA Element HT5 (USA). The following parameters were determined: hematocrit, hemoglobin, red blood cells, white blood cells, platelets.

Blood for the BB was drawn from the vein in the fasted condition in a vacuum test tube with a coagulation activator in an amount of at least 1.0 ml. The serum was separated on a laboratory centrifuge CLMN-R10-01-Elecon-M (Russia) at 2700 min-1 for 3...5 minutes and then examined on an automatic biochemical analyzer Super Z (China). The following parameters were determined: fractional bilirubin, total protein, urea, creatinine, glucose, and cholesterol. For ultrasound of the uterus and ovaries in a 3D mode, a veterinary ultrasound scanner Cymedica (China) with a 5 MHz linear sensor was used. The study evaluated the size of the ovaries and the body of the uterus, as well as their structure. The obtained data were statistically processed using BioStat 3.03 software. In the future, during the entire time of the study investigating the effect of the use of SEX BARRIER® by owners at home on the clinical status, morphological and biochemical blood parameters of female cats, the same diagnostic procedures and studies were carried out every three months from the moment of the animal’s enrollment in the experiment, as prior to the experiment initiation. In addition, after 6 months of the experiment, an additional questionnaire was conducted with questions related to the compliance of using the drug during the past period with the requirements of the instructions.

Results and discussion

Medical history. Analysis of the results of the owners initial survey demonstrated that the majority (87 %) of female cats included in the study never leave the place of keeping, 70 % of the animals consume ready-made industrial meals, 20 % receive a mixed type of feeding and 10 % of animals are on natural feeding. When interviewing the owners in 6 months after the start of the study about compliance with the requirements of the instructions regarding the frequency of use and dosage of the drug, the following data were obtained:

• 40 % of the owners, who regularly administered SEX BARRIER® drops in their female cats for estrus delay, a few times violated the interval of drug use (towards increase) which constitutes 14 days according to the instruction;
• 20 % of cat owners multiple times insignificantly decreased the dosage;
• 10 % of cat owners increased the drug dosage during its use for interruption of already started heat (table 2).

No reduction or increase in the duration of the course of the drug used by for estrus interruption, which constituted according to the instructions 3 to 5 days, was observed.

All owners of the female cats from the experimental groups during the experiment also used the bi-hormonal drug SEX BARRIER® according to the regimen for delaying estrus, which allows the owners to maintain anestrus for a long time in the animal. In case of unintentional deviation from this schedule at the beginning of estrus, cat owners administered a drug to the animals on the same or the next day according to the regimen for interrupting estrus. Within 3...5 days of the course of the drug use, behavioral signs of estrous behavior completely stopped in 100% of cats, and in 10 days after the disappearance of estrus signs, owners were recommended to use the drug according to the scheme for delaying estrus, maintaining the dosage and frequency of use.

During the period of using the drug according to the scheme for delaying estrus, estrous behavior was not registered in any female cat from the experimental group. Animals of the control group during the study period spontaneously became in heat with different frequency.

Taking into account the possibility of similar violations in the drug use and in the further course of the experiment, it was decided to monitor compliance with the requirements of the instruction. For this purpose the owners were suggested to inform investigators both about the occurrence of estrus on the day of its beginning, and about the intention to use the drug according the scheme for estrus delay in order to receive necessary instructions from a specialist.

Clinical examination. According to the results of clinical examinations and determination of BW of female cats receiving SEX BARRIER®, there were no registered significant differences from the control group animals and deviations from the reference values of the target physiological normal parameters. Body weight of the female cats during enrollment in the study (April 2016) remained within 3.2...4.3 kg. According to the results of subsequent quarterly assessment, BW of animals in the experimental and control groups at each stage of the assessment varied within 10 ... 15%, both to the greater or lesser extent as compared to the number registered at the start of the study (table 3).

Uterine and ovarian US. Primary ultrasound of the uterus and ovaries demonstrated no deviations in the size and structure of the marked organs in all animals included in the study. This fact indicates the absence of pathology of reproductive organs in female cats at the start of the study. Subsequent quarterly ultrasounds of the reproductive organs in cats from the experimental and control group demonstrated normal size of the uterus, which did not significantly change until the study was completed. Ultrasound also ruled out polycystosis and other pathologies of the ovaries. Thus, ultrasound of the uterus and ovaries during the study did not reveal any negative effect of the drug SEX BARRIER® on the reproductive organs of female cats in conditions of its regular and not always proper use by owners at home.

Complete blood count and biochemistry. All monitored blood parameters in female cats of the experimental and control groups during the entire experiment were within the reference intervals.

Morphological parameters. The CBC results of female cats from the experimental group during the study period demonstrate that the concentration of hemoglobin, Erythrocytes, Leukocytes and platelets did not differ from the similar parameters in the control group and remained within the reference values (tables 4, 5). This indicates the safety of long-term use of the drug in relation to possible adverse effects on blood morphology.

Biochemical parameters. During the BB, the number of determined parameters included bilirubin as indicator associated with impaired hemoglobin metabolism, liver function and bile ducts; serum aminotransferases as markers of differential diagnosis of various diseases of internal organs; creatinine and urea as indicators of renal pathology; total protein for evaluating synthetic liver function; glucose and cholesterol as indicators of carbohydrate and fat metabolism, respectively. According to the results of a quarterly study of the specified parameters for 30 months, all controlled biochemical markers in female cats from the experimental groups were within the physiological normal range.

At the same time, no significant differences between the experimental and control animals were detected as well (tables 6, 7). Based on the data obtained, it can be concluded that the long-term use of SEX BARRIER® drops by owners at home according to the schemes for delaying and interrupting estrus, even taking into account their not always correct use by owners, does not lead to changes in the exchange of macronutrients in the animals. This confirms the safety of long-term use of the drug in relation to its effect on the metabolism of proteins, fats, carbohydrates and the functioning of the main excretory body systems.

* reference interval of the veterinary laboratory Assistant-Vet

* reference interval of the veterinary laboratory Assistant-Vet

* reference interval of the veterinary laboratory Assistant-Vet

* reference interval of the veterinary laboratory Assistant-Vet

Conclusion

The effects of prolonged use of oral bi-hormonal contraceptive drug SEX BARRIER® by owners for delays and interruption of estrus in domestic female cats were monitored for more than two years from April 2016 till September 2018. The initial survey of the owners demonstrated that the initial data of animals in relation to the type of their housing and feeding differed significantly. In addition, a survey conducted in 6 months from the start of the drug use demonstrated that over the past period 40 % of owners who regularly administered SEX BARRIER® drops to their female cats to delay estrus, sometimes exceeded the interval of the drug use; 20 % of owners reduced, and 10% of cat owners exceeded the recommended dosage of the drug when using it to interrupt the onset of estrus.

At the same time, all owners confirmed 100% efficacy of the bi-hormonal drug SEX BARRIER® for both interrupting and delaying estrus in female cats. In our opinion, this is related to the minimum effective dose of AS and a variable course of the drug to interrupt estrus. These parameters make it possible to create the concentration of hormones in the target organs necessary for suppression of behavioral manifestations of estrus during the stated period. It should be noted that suppression of estrous behavior is maintained without a long-term negative effect of the drug on the clinical status, genital area, morphology and biochemistry of the cats’ blood due to the synergy of low doses of the AS and the availability of a reserve in duration of the course for interrupting estrus.

Obviously, to some extent the fact that the sample was analyzed among animals whose owners had a history of positive experience of the drug use to regulate the sexual behavior of female cats also played an important role. These theses were confirmed in this study and in the previous work [6]. Thus, it can be stated that oral bi-hormonal oral SEX BARRIER® takes into account the physiological characteristics of the estrous cycle, sexual constitution and hormonal status of the female cats; it allows the owners to effectively, safely and in a reversible manner regulate the reproductive function and is an alternative to surgical castration. Surgical removal of the ovaries and uterus in cats in 13% of cases does not allow to achieve a lifelong suppression of estrous behavior [4]. This surgical intervention is irreversible and causes significant damage to the endocrine system, which leads to certain metabolic disorders that can significantly reduce the quality of life of the animal [7].

. In a physical and instrumental study of the animals conducted for more than two years on a quarterly basis, it was determined that in the experimental cats the target parameters for the entire period did not exceed the limits of the physiological norm. There were also no significant differences in the BW of experimental and control female cats. Ultrasound of the uterus and ovaries during the study did not reveal a negative effect of the drug SEX BARRIER® on the reproductive organs of female cats from the experimental groups in the conditions of its regular use by owners at home, even though there are some deviations from the exact recommendations given in the instructions. The results of the CBC during the study period showed complete safety of a long-term use of the drug regarding the possibility of adverse effects on blood morphology.

According to the results of the quarterly BB, all controlled biochemical parameters in female cats of the experimental groups were within the physiological normal range, which is the evidence of the absence of significant changes in the metabolism of female cats during the long-term use of a bi-hormonal contraceptive. Taking into account the results of the study [6] and the results of this work, the use of oral bi-hormonal drug SEX BARRIER® drops for regulation of reproductive function in both clinical and household conditions (where there are the differences in the conditions of keeping and feeding the animals and the possibility of some deviations from the conditions recommended in the instructions for the drug use) does not lead to impairment in the genital sphere, clinical status, morphological and biochemical parameters of the blood of the female cats. Based on this, we can conclude that the use of the oral bi-hormonal contraceptive drug SEX BARRIER® is currently the most humane, physiological and safe method that allows the owners to effectively regulate the reproductive function of female cats in domestic conditions.

Conflict of Interes

The manufacturer of the drug SEX BARRIER® and the sponsor of this study is LLC Research and Production Company SKiFF. The decision to publish the results of scientific work belongs to the developer LLC Research and Production Company SKiFF.

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