Nonsurgical fertility control for managing free-roaming dog populations: a review of products and criteria for field applications

In vitro evaluation of oral contraceptives on long-tailed macaque (Macaca fascicularis) primary ovarian cells

Hormonal contraception has been advocated as an alternative population control method for the long-tailed macaque population, which has increased exponentially due to anthropogenic changes and incidental food subsidies from human food waste. Risks of increased zoonosis and conflict are imminent if the population growth of long-tailed macaques is unchecked. However, there's a gap in the literature about the effect of hormonal contraceptives on long-tailed macaque reproductive tissues cell line. The present study aims to investigate the effect of oral contraceptives (Nordette, Noriday, and Ella) on long-tailed macaque ovarian cells. We determine the cell viability and cytotoxicity as well as the morphological changes of the drugs on long-tailed macaque ovarian cells using the MTT assay, Acridine orange/propidium iodide double staining method, morphological examination, and the 4, 6-diamidino-2-phenylindole (DAPI) staining method. For the MTT assay, The drugs were dissolved in culture media before use to have a concentration ranging from 0.5 μg/mL, 2.5 μg/mL, 0.125 μg/mL, 0.0625 μg/mL, and 0.0315 μg/mL to have three replicates for each treatment. In contrast, the concentration of 0.0315 μg/mL was used for the morphological and histopathological analysis. The result of the study indicates that human oral contraceptives (Nordette, Noriday, and Ella) inhibit the growth of long-tailed macaque ovarian cells and induce apoptosis in a concentration- and time-dependent manner (at a concentration of 0.0315 μg/mL and an IC50 lower than 10 μg/mL), With a statistically significant value of ****P < 0.001 for each drug compared to the negative control. The result of the present study contributes toward addressing the gap in the literature on the effect of oral contraceptives in long-tailed macaque ovarian cells. Hence, we conclude that human oral contraceptives (Nordette, Noriday, and Ella) are safe and effective in long-tailed macaque ovarian cells as such could be used to develop non-invasive oral contraceptives for controlling the population of long-tailed macaques as an alternative population control method.

Male animal sterilization: history, current practices, and potential methods for replacing castration

Sterilization and castration have been synonyms for thousands of years. Making an animal sterile meant to render them incapable of producing offspring. Castration or the physical removal of the testes was discovered to be the most simple but reliable method for managing reproduction and sexual behavior in the male. Today, there continues to be global utilization of castration in domestic animals. More than six hundred million pigs are castrated every year, and surgical removal of testes in dogs and cats is a routine practice in veterinary medicine. However, modern biological research has extended the meaning of sterilization to include methods that spare testis removal and involve a variety of options, from chemical castration and immunocastration to various methods of vasectomy. This review begins with the history of sterilization, showing a direct link between its practice in man and animals. Then, it traces the evolution of concepts for inducing sterility, where research has overlapped with basic studies of reproductive hormones and the discovery of testicular toxicants, some of which serve as sterilizing agents in rodent pests. Finally, the most recent efforts to use the immune system and gene editing to block hormonal stimulation of testis function are discussed. As we respond to the crisis of animal overpopulation and strive for better animal welfare, these novel methods provide optimism for replacing surgical castration in some species.

Development of peptides for targeting cell ablation agents concurrently to the Sertoli and Leydig cell populations of the testes: An approach to non-surgical sterilization

The surgical sterilization of cats and dogs has been used to prevent their unwanted breeding for decades. However, this is an expensive and invasive procedure, and often impractical in wider contexts, for example the control of feral populations. A sterilization agent that could be administered in a single injection, would not only eliminate the risks imposed by surgery but also be a much more cost-effective solution to this worldwide problem. In this study, we sought to develop a targeting peptide that would selectively bind to Leydig cells of the testes. Subsequently, after covalently attaching a cell ablation agent, Auristatin, to this peptide we aimed to apply this conjugated product (LH2Auristatin) to adult male mice in vivo, both alone and together with a previously developed Sertoli cell targeting peptide (FSH2Menadione). The application of LH2Auristatin alone resulted in an increase in sperm DNA damage, reduced mean testes weights and mean seminiferous tubule size, along with extensive germ cell apoptosis and a reduction in litter sizes. Together with FSH2Menadione there was also an increase in embryo resorptions. These promising results were observed in around a third of all treated animals. Given this variability, we discuss how these reagents might be modified in order to increase target cell ablation and improve their efficacy as sterilization agents.

Capturing free-roaming dogs for sterilisation: A multi-site study in Goa, India

Sterilisation and rabies vaccination programs seek to manage free-roaming domestic dog (Canis familiaris) populations with the aim to reduce inter-species disease transmission and conflicts. As effective, permanent, remotely-administered options are not yet available for sterilisation, and oral vaccination is not yet commonly used; free-roaming dogs are typically captured for these interventions. There is a paucity of information describing how dog capture rates change over time within defined areas following repeated capture efforts. This data is needed to allow efficient dog capture programmes to be developed. Using spatial co-ordinates of dog capture, we characterise where dogs are more likely to be captured in six catch-sterilise-release campaigns, in Goa state, India. Combining capture numbers with population survey data collected in five sites, we document the increasing difficulty of catching entire (non-sterilised) dogs as sterilisation coverage increases and demonstrate how this leads to increased unit costs. Accounting for the extra resources required to capture dogs when sterilisation coverage is high will improve estimation of the resources required to manage free-roaming dog populations and assist in planning the most efficient intervention strategies.

"Is free-roaming a key factor determining lifespan? An epidemiological study on the life expectancy of Turkish companion dogs"

Companion dog lifespan data has exclusively been studied in developed economies. Here we report results from n = 1312 privately owned Turkish companion dogs (Free-roaming and non Free-roaming) from an online survey analyzed through Kaplan-Meier analysis and Cox regression. Median survival time (MST) was 13 years. Most common causes of death were viral infections (n = 126), cancer (n = 60), and cardiovascular disease (n = 36). Desexing (χ2 = 31.6, P = 2E-8), being a mixed breed (χ2 = 6.4, P = 0.01), and regular preventative care (χ2 = 5.3, P = 0.02) significantly increased lifespan. Roaming freely significantly decreased lifespan (χ2 = 19.5, P = 1E-5). Dogs living in duplexes and single-family homes lived longer than dogs living in apartments and houses on acreage (χ2 = 10.5, P = 0.01). Owner income or education levels did not correlate with lifespan. In a Cox model, only desexing (HR = 0.478, P = 0.0006), living in a house on acreage (HR = 2.30, P = 0.0064) and being allowed to roam freely (HR = 1.59, P = 0.041) remained significant. Even though there are studies that contain information about dog demographics and mortality data outside of the western countries, to our knowledge, this is the first study of factors that influence companion dog lifespan in a middle income economy. While much of our findings correlate with those from developed economies, our sample also lets us study the effects of factors not commonly found in developed economies on dog lifespan, such as being allowed to roam freely.

Analysis of human rabies deaths reported at two hospitals in Karachi, Pakistan: a call to save lives by reforming rabies prevention facilities

BACKGROUND

Rabies is endemic in low- and middle-income countries. It is caused mainly by the bite of a rabid dog and is fatal if not treated effectively and in a timely manner with quality post-exposure prophylaxis. Despite a profusion of private and public healthcare centres in Sindh province, most are ill-equipped to treat dog bites.

METHODS

We analysed 129 human deaths from rabies who presented at the emergency departments of two tertiary care hospitals in Karachi over 10 y. Demographic data, time, location of the bite and distance travelled to report symptoms of rabies were recorded.

RESULTS

Most victims were male, and children were more often affected; almost none had received post-exposure prophylaxis. A total of 12% of bites were on the face, head or neck. The mean incubation period was 56 d. Most (60%) of the rabies victims travelled long distances, hoping to receive treatment.

CONCLUSIONS

Rabies deaths were either due to a lack of awareness or the non-availability of rabies immunobiologicals within easy reach. Public health services must raise awareness, conduct surveillance and provide appropriately spaced centres for free treatment of dog bites. This lethal disease must be prevented at all costs.

Epigenetic repression of gonadotropin gene expression via a GnRH-mediated DNA delivery system

The reproductive axis is activated by gonadotropin-releasing hormone (GnRH), which stimulates the pituitary gonadotropes to secrete hormones that drive gonadal function and steroidogenesis. Thus repression of this axis, which is conserved across mammals and sexes, can reduce steroid levels and/or prevent reproduction. Steroid-dependent pathologies, including various cancers, are commonly treated with GnRH super-analogs which have long-term side-effects, while humane solutions for controlling reproduction in domestic and wild animal populations are lacking. GnRH-conjugated toxins are undergoing clinical trials for GnRHR-expressing cancer cells, and have been examined for gonadotrope ablation in animals, but showed low and/or transient effects and administration of toxins has many potential complications. Here we exploit GnRH targeting to gonadotropes to deliver DNA encoding an effector that induces gonadotropin gene repressive epigenetic modifications which are perpetuated over time. Several layers of specificity are endowed through targeting to GnRHR-expressing cells and due to local cleavage of the peptide packaging the DNA; the DNA-encoded effector is expressed and directed to the target genes by the DNA binding domain of a highly specific transcription factor. This design has multiple advantages over existing methods of shutting down the reproductive axis, and its modular design should allow adaptation for broad applications.

Effects of a Recombinant Gonadotropin-Releasing Hormone Vaccine on Reproductive Function in Adult Male ICR Mice

Gonadotropin-releasing hormone (GnRH) regulates the reproductive endocrine system in mammals. The GnRH immunocontraception vaccine can aid animal population control and management. We evaluated a recombinant GnRH fusion protein with the adjuvant MONTANIDE ISA 206 VG as a GnRH vaccine in adult male ICR mice by evaluating anti-GnRH antibodies; concentrations of follicle-stimulating hormone (FSH), luteinizing hormone (LH), and testosterone; testis size and histomorphology; and semen quality. Response was assessed after intramuscular administration of the vaccine to mice in weeks 0, 4, and 8. The vaccine induced specific antibody response by week 5, with peak of antibody levels observed by week 13 and a declining level thereafter until the end of the study at week 24. Furthermore, it reduced serum FSH, LH, and testosterone concentrations. The vaccinated mice exhibited testicular atrophy and reduced sperm quality, concentration, morphology, and viability compared to control males. The outcomes of pairings of treated males with untreated females revealed reduced mating, pregnancy rates and number of litters compared to control pairings. Assessment of this GnRH vaccine in different species could assist its development for future applications.

A novel approach to nonsurgical sterilization; application of menadione-modified gonocyte-targeting M13 bacteriophage for germ cell ablation in utero

There remains a compelling need for the development of nonsurgical sterilizing agents to expand the fertility management options for both domestic and feral animal species. We hypothesize that an efficacious sterilization approach would be to selectively ablate nonrenewable cell types that are essential for reproduction, such as the undifferentiated gonocytes within the embryonic gonad. Here, we report a novel strategy to achieve this goal centered on the use of a chemically modified M13 bacteriophage to effect the targeted delivery of menadione, a redox‐cycling naphthoquinone, to mouse gonocytes. Panning of the M13 random peptide ‘phage display library proved effective in the isolation of gonocyte‐specific targeting clones. One such clone was modified via N‐succinimidyl‐S‐acetylthioacetate (SATA) linkage to the N‐terminus of the major PVIII capsid protein. Subsequent deacetylation of the SATA was undertaken to expose a thiol group capable of reacting with menadione through Michael addition. This chemical modification was confirmed using UV spectrophotometry. In proof‐of‐concept experiments we applied the modified ‘phage to primary cultures of fetal germ cells and induced, an approximately, 60% reduction in the viability of the target cell population. These studies pave the way for in vivo application of chemically modified M13 bacteriophage in order to achieve the selective ablation of nonrenewable cell types in the reproductive system, thereby providing a novel nonsurgical approach the regulation of fertility in target species.

Short Term Safety, Immunogenicity, and Reproductive Effects of Combined Vaccination With Anti-GnRH (Gonacon) and Rabies Vaccines in Female Feral Cats

Overpopulation of free-roaming cats is a major problem leading to negative impacts on animal health and welfare, public nuisance, transmission of zoonotic diseases, and well-documented harm to wildlife. Surgical sterilization had failed to provide a practical solution to free-roaming cats' overpopulation under field conditions; therefore, efficient and safe non-surgical immunocontraception methods are aspired. Rabies is a deadly virus that may infect people and animals. However, the safety and efficacy of combined vaccination with anti-GnRH and rabies vaccines in feral cats, which often suffer from disrupted health conditions and experienced high stress level, has never been studied. Therefore, our objective was to examine the short-term safety and efficacy of anti-GnRH vaccine (Gonacon), in combination with rabies vaccine in female feral cats. Mature feral female cats were captured and divided into the following groups: (I) GonaconX1-Rabies: queens vaccinated with both Gonacon and rabies (n = 5); (II) GonaconX2-Rabies: queens vaccinated twice with Gonacon (3 weeks apart) and with Rabies (n = 4); (III) OVx-Rabies: queens ovariohysterectomized and vaccinated with rabies (n = 4); (IV) Intact-Rabies: queens vaccinated against rabies and remained intact (n = 3). Comprehensive veterinary examinations and blood tests were performed every 2 weeks for 14 weeks. Data were analyzed by Repeated-Measures-ANOVA or Fisher-Exact-Test. There were neither systemic nor local adverse reactions at the vaccination sites. Blood count (PCV, TS, RBC, HGB, HCT, WBC) and chemistry (Total protein, Total globulin, Albumin, Urea, Creatinine, Creatine kinase, Bilirubin, GGT, ALT, AST) analyses revealed no differences among groups. There were no differences in serum rabies antibodies titers among groups, and queens kept a protective titer (>0.5 IU/mL) starting at 2–4 weeks after vaccination. Anti-GnRH antibodies were detected in all Gonacon-vaccinated queens, excluding one queen (GonaconX2-Rabies group). Anti-müllerian hormone serum concentrations reduced significantly after ovariohysterectomy, as well as gradually following vaccination with Gonacon, but it remained high in intact queens. Evaluation of vaginal cytology and ovarian histology suggested that reproductive cyclicity was suppressed in Gonacon-vaccinated queens. Our results support the conclusion that in the short term, the combined vaccination with Gonacon and rabies is safe and effective in female feral cats. However, further long-term studies are warranted to test this immunologic regimen in feral cats.

Immunocontraceptive potential of a GnRH receptor-based fusion recombinant protein

BACKGROUND

The management of stray dog population has been of utmost importance due to their overpopulation, increase in dog bites incidence, and rabies. Contraceptive vaccines, a non-surgical alternative to spaying and neutering are viewed as a valuable option for the management of dog population. In this study, the contraceptive potential of a recombinant fusion protein containing the three genes GnRH, GnRH receptor, and ZP3 was explored.

RESULTS

The gene fragment encoding GnRH, GnRHR, and ZP3 along with the antigenic epitopes of canine distemper virus and tetanus toxoid was assembled, synthesized, and cloned into pET28a expression vector. The resulting construct GVAC08 was successfully transformed into BL21DE3 strain of E. coli and confirmed by colony PCR. The recombinant GVAC08 protein was expressed and purified using Ni-NTA and was confirmed to be a 50-KDa protein by SDS PAGE and Western blot. Mice were immunized with the GVAC08 protein using Freund's complete adjuvant followed by a booster using Freund's incomplete adjuvant. This induced a high antibody titer against GnRH, GnRH receptor, and ZP3 which was determined by ELISA.

CONCLUSION

Mating studies showed that the GVAC08 recombinant protein was able to reduce the litter size in immunized mice showing improved efficacy. However, the vaccine candidate with further improvements will be a viable contraceptive vaccine.

A preliminary study of transabdominal ultrasonic wave treatment on the germinal tissues of dog ovaries as a contraceptive approach

The aim of this study was to investigate effects in dogs of ultrasonic waves on the ovarian germinal tissues. There was assignment of ovaries of each dog being a control (right ovary) or treated (left ovary) tissue, regardless of the estrous cycle status. For the treated ovary, the ultrasonic probe was set at a frequency of 1 MHz and power of 1.5 W/cm² and placed on the skin at a location in close proximity to the left ovary that was predetermined using ultrasonography. Subsequently there was a focusing of the waves for 5 min on the tissues of the treated ovary. The treatment was repeated three times at 48 -h intervals. There was placement of the probe at the same proximity to the control ovary; however, the probe was not activated. Ovariectomies for histological examination were performed 30 (five dogs) and 60 (five dogs) days following the ultrasonic treatments. Histopathological examination results indicated there was a reduction in numbers of primordial follicles of four dogs and oocyte degeneration in the Graafian and primordial follicles of five dogs. In most dogs, the degeneration of the granulosa cells of the Graafian follicle was observed in the treated ovaries. The results indicate the treatment of ovaries with transabdominal ultrasonic waves at a 1 MHz frequency, and 1.5 W/cm² power for three times with each treatment lasting for 5 min at a 48-h interval, did not result in complete ablation of the germinal tissues of the ovary during the 2-month period subsequent to treatment.

Effects of Gender, Sterilization, and Environment on the Spatial Distribution of Free-Roaming Dogs: An Intervention Study in an Urban Setting

Information concerning the factors affecting the circulation and distribution of free-roaming dogs is crucial in developing control actions and limiting the spread of zoonoses. The present study analyzes the influence of gender, sterilization, and environment on the spatial distribution of free-roaming dogs in urban settings. Animals were captured/recaptured in seven consecutive morning sampling efforts conducted at 2-monthly intervals in control and intervention areas in a medium-size town in southeastern Brazil. Capture locations were georeferenced and captured animals were microchipped before being released at their original capture sites. Dogs captured in the intervention area were subjected additionally to surgical sterilization prior to release. Home range (HR) areas were calculated by applying the minimum convex polygon method to dogs that had been captured at least three times. Land coverage zones were determined from satellite images and overlaid on maps of the study areas along with the locations of 22 commercial food outlets. HR areas showed a global mean of 448 m² and a median of 28 m², values that were smaller than those reported previously for dogs in rural regions. The median HR of females (64.m²) was higher than that of males (15 m²), while median HRs of animals in the control and intervention areas were similar (27 and 28.5 m², respectively). Variability of HR was high, although animals with small HRs predominated. Free-roaming dogs grouped primarily in urbanized and transitional regions, and their spatial distribution was positively correlated with locations of commercial food outlets. While sterilization did not influence HR size, the search for food was a key factor in determining mobility and spatial aggregation of free-roaming dogs. Our findings are pertinent in understanding the ecology of free-roaming dogs in urban environments and will be applicable to strategies aimed at promoting animal welfare and preventing the dissemination of zoonoses.

The effects of therapeutic ultrasound waves on testicular tissue, echogenicity, semen quality, oxidative stress, and acute-phase proteins in dogs

The application of high-intensity ultrasound waves has been investigated as one of the non-invasive methods of contraception in several species. This study was aimed to investigate the mechanism of contraception in dogs using ultrasound waves by measuring acute-phase proteins and oxidative stress indices. Ten mixed-breed adult and fertile dogs were divided into two equal treatment and control groups. The dogs' testes in the treatment group were exposed to ultrasound waves at an intensity of 1.5 W/cm² and a frequency of 1 MHz, 3 times for 5 min, and every 48 h. Blood sampling (before exposure, and 3, 5, 7, 21, 35, 49, and 63 days after exposure), semen collection (before exposure, and 4, 6, and 8 weeks after exposure), testicular ultrasonography (before exposure, and 4, 6, and 8 weeks after exposure), and testis histopathology (30 and 60 days after exposure) were performed during the study. The echogenicity of the dogs' testes significantly increased in the treatment group from week 6 onwards (P = 0.001). The concentration and progressive motility of spermatozoa in all samples, from both the control and the treatment groups, were normal at different times during the study. There was no significant change in the concentration of serum testosterone. The activity of superoxide dismutase and glutathione peroxidase enzymes on days 3, 5, and 7 and catalase activity on day 3 significantly decreased in the treatment group compared to those of the control group (P = 0.006). In addition, malondialdehyde concentration significantly increased in the treatment group on days 3, 5, and 7 (P < 0.0001). The concentrations of C-reactive protein, serum amyloid A, and alpha-1-acid glycoprotein significantly increased on days 3, 5, and 7 compared to those of the control group (P = 0.005). To sum up, high-intensity ultrasound waves could activate the process of the acute phase response of inflammation and oxidative stress and induce further damage to the testicular tissue in dogs. This was mainly observed in the first week after the testes were exposed to ultrasound waves.

Prevalence, seasonal and geographical distribution of parasitic diseases in dogs in Plateau State Nigeria: a 30-year retrospective study (1986-2015)

Parasitic diseases of dogs are now major economic and public health issues in Nigeria due to indiscriminate reproduction of dogs, lack of appropriate policies on pet ownership and diseases control as well as inadequate veterinary care. In order to understand the prevalence, seasonal variation and distribution of parasitic diseases of dogs in this region of Nigeria, the present study conducted a 30-year retrospective analysis in the referral veterinary centre, Vom, and analysed data using the Chi square test and the factor analysis. Of the 26,844 dogs handled between January 1986 and December 2015, 17,663 (65.8%) had different parasitic diseases. Yearly distribution of parasitic diseases varied significantly (p < 0.0001) and ranged between 52.0 and 85.4%. Age, seasonal and disease specific prevalence rates ranged between 2.8 and 80.5%. Prevalence rates in females 78.2% (95% CI 77.6-78.9) and indigenous breed 70.0% (95% CI 69.2-70.7) were significantly higher (p < 0.0001) from those of the males 47.2% (95% CI 46.2-48.1) and exotic breeds of dogs 60.7% (95% CI 59.8-61.6), respectively. Ancylostomosis was the most prevalent (15.9%) disease while Barkin Ladi recorded the highest regional prevalence. It is pertinent to enact appropriate disease control policies and observe control programmes including vector control and improved hygiene to curtail the economic and public health threats associated with these diseases.

Desexing Dogs: A Review of the Current Literature

Background: Desexing dogs is promoted for population control, preventative healthcare, and behavior modification. Common methods are orchiectomy and ovariectomy/ovariohysterectomy. GnRH superagonist implants are available in some areas. Alternative methods like vasectomy and salpingectomy/hysterectomy are uncommon. The terminology used to describe desexing is inconsistent and contradictory, showing a need for the adaption of standardized terminology. Population Control: Surprisingly, empirical studies show no effects of desexing on population control in companion and shelter dogs despite desexing being consistently recommended in the literature. There is evidence for a population control effect in free-roaming dogs, where desexing also has benefits on zoonotic disease and bite risk. Population control in free-roaming dogs is mostly correlated with female, not male desexing. Health and Lifespan: Desexing affects numerous disease risks, but studies commonly neglect age at diagnosis and overall lifespan, age being by far the most important risk factor for most diseases. We argue that lifespan is a more important outcome than ultimate cause of death. A beneficial effect of desexing on lifespan is consistently demonstrated in females, while evidence for a beneficial effect in males is inconsistent. Studies are likely biased in desexing being a proxy for better care and desexed dogs having already lived to the age of desexing. Desexing reduces or eliminates common life-limiting diseases of the female reproductive system such as pyometra and mammary tumors, while no analogous effect exists in males. Disease risks increases across sexes and breeds include cruciate ligament rupture, various cancers, and obesity. Urinary incontinence risk is increased in females only. Various other disease risk changes show considerable variability between breeds and sexes. Behavioral Effects: Desexed males show reduced libido, roaming, conspecific mounting, and urinary marking frequency, as well as reduced male dog-directed aggression in a majority of males desexed for behavioral reasons. There is a detrimental effect on the risk and progression of age-related cognitive dysfunction. Desexed dogs may be less likely to cause bite injuries across sexes. The evidence for other effects such as human-directed aggression, human or object mounting, resource guarding, or shyness and anxiety is inconsistent and contradictory. There are few studies specific to females or individual breeds. Conclusions: The evidence for a beneficial effect of desexing is stronger in female than in male dogs; however, there is significant variation between breeds and sexes, and more research is needed to further elucidate these differences and to arrive at individualized evidence-based recommendations for clinical practice.

Demographic characteristics of free-roaming dogs (FRD) in rural and urban India following a photographic sight-resight survey

An understanding of the core demographic characteristics of the sub-populations of FRD is essential to effectively implement both rabies control interventions through mass vaccination of FRD, and dog population control programmes. This study compares the data obtained following photographic sight-resight surveys in rural (Shirsuphal village in west India) and urban (Municipal Corporation Panchkula in north India) locations . A total of 263 and 1408  FRD were seen at least once through 617 and 3465 sightings in the rural and urban sites, respectively. The rural location had a lower proportion of females (OR 0.5, 95% CI 0.4-0.7) and a higher proportion of poor and fair conditioned dogs (OR 1.8, 95% CI 1.3-2.3) compared to the urban setting. The rural site also had fewer active FRD (OR 0.6, 95% CI 0.5-0.7) and FRD were less likely to be sighted within 20 m of garbage points (OR 0.3, 95% CI 0.2-0.3) compared to the urban site. The demographic composition of the FRD population was found to vary within the urban location, with the odds of sighting a de-sexed dog being significantly higher in residential areas compared to other areas. The study underlines the importance of knowing the demographic composition of FRD for implementation of effective interventions against rabies. Fewer female dogs in the rural location indicate that spaying could be an effective tool for dog population management in this setting, while presence of dogs within 20 m of garbage points in urban settings highlights that an improved garbage management may reduce the carrying capacity of the urban locality resulting in smaller FRD population. It is concluded that quick and low cost surveys can generate useful demographic data for FRD in urban and rural settings which can be useful to understand the epidemiology of rabies and its control.

BOARD INVITED REVIEW: Immunocontraception as a possible tool to reduce feral pig populations: recent and future perspectives

The feral pig populations of many countries continue to increase. Scientific studies on population size are scarce, while the numbers of reported observations on presence of and damage caused by feral pigs are increasing. Feral pigs can carry and spread several diseases (including zoonotic), but African Swine Fever (ASF) is of most concern. It is a highly transmissible viral disease associated with an extremely high mortality rate. Since 2009 ASF has appeared in several European countries, with cases being identified first among local feral pigs and consequently in domestic pig production units, indicating a clear linkage with the movement of the feral pig population and the spread of the disease across national boundaries. Control of feral pig populations is currently under discussion. Because massive culling raises questions of animal welfare and ethics, fertility control could represent an important and effective means to control feral pig populations. Contraceptive vaccines have been used with some degree of success in many wild species because they are able to provide a long-term effect without any consequent health problems. However, extensive and efficacious use of vaccines to control feral pig populations is not simple. The aim of this article was to review the progress in immunocontraception use in feral pigs, providing an account of the current status and future perspectives.

Nanocarrier-mediated delivery of α-mangostin for non-surgical castration of male animals

The overpopulation of abandoned and stray companion animals has become a global crisis. The main purpose of this study was to develop a novel nanomedicine-based antifertility compound for non-surgical castration of male animals. Mangosteen (Garcinia mangostana L) pericarp extract has been shown to exhibit anti-fertility property. α-mangostin (AM)-loaded nanostructured lipid carrier (AM-NLC) was developed to improve male germ cell apoptosis. This study was conducted to investigate physicochemical properties of AM-NLC and determine the biological effects of AM-NLC on spermatogonia cells and testicular explants obtained from castrated testes. AM-NLC was produced through a hot homogenization technique. The negatively charged particle of AM-NLC was nano-sized with a narrow dispersity. AM-NLC exhibited antiproliferative activity towards spermatogonium cells. It induced apoptosis in the cells. In addition, AM-NLC exhibited anti-inflammatory activities in lipopolysaccharide-activated macrophages. Abnormal anatomy of seminiferous tubule was noted following treatment of testicular explant with AM-NLC. This nanomedicine-based sterilant would be a promising platform that may have utility in non-surgical castration of male animals by intra-testicular injection.

The Role of Dog Population Management in Rabies Elimination-A Review of Current Approaches and Future Opportunities

Free-roaming dogs and rabies transmission are integrally linked across many low-income countries, and large unmanaged dog populations can be daunting to rabies control program planners. Dog population management (DPM) is a multifaceted concept that aims to improve the health and well-being of free-roaming dogs, reduce problems they may cause, and may also aim to reduce dog population size. In theory, DPM can facilitate more effective rabies control. Community engagement focused on promoting responsible dog ownership and better veterinary care could improve the health of individual animals and dog vaccination coverage, thus reducing rabies transmission. Humane DPM tools, such as sterilization, could theoretically reduce dog population turnover and size, allowing rabies vaccination coverage to be maintained more easily. However, it is important to understand local dog populations and community attitudes toward them in order to determine whether and how DPM might contribute to rabies control and which DPM tools would be most successful. In practice, there is very limited evidence of DPM tools achieving reductions in the size or turnover of dog populations in canine rabies-endemic areas. Different DPM tools are frequently used together and combined with rabies vaccinations, but full impact assessments of DPM programs are not usually available, and therefore, evaluation of tools is difficult. Surgical sterilization is the most frequently documented tool and has successfully reduced dog population size and turnover in a few low-income settings. However, DPM programs are mostly conducted in urban settings and are usually not government funded, raising concerns about their applicability in rural settings and sustainability over time. Technical demands, costs, and the time necessary to achieve population-level impacts are major barriers. Given their potential value, we urgently need more evidence of the effectiveness of DPM tools in the context of canine rabies control. Cheaper, less labor-intensive tools for dog sterilization will be extremely valuable in realizing the potential benefits of reduced population turnover and size. No one DPM tool will fit all situations, but if DPM objectives are achieved dog populations may be stabilized or even reduced, facilitating higher dog vaccination coverages that will benefit rabies elimination efforts.

Owned dog ecology and demography in Villa de Tezontepec, Hidalgo, Mexico

Dog overpopulation in developing countries has negative implications for the health and safety of people, including the transmission of zoonotic diseases, physical attacks and intimidation to humans and animals, as well as impacts on canine welfare. Understanding the ecology and demographic characteristics of a dog population can help in the planning and monitoring of canine population control programs. Little data exist regarding demography and dynamics of domestic dog populations in semi-urban areas in Mexico. A cross-sectional study was carried out between October 21 and November 7, 2015, to characterize the dog ecology and demography in Villa de Tezontepec, Hidalgo, Mexico. A face-to-face survey was used to collect data from randomly selected households in four contiguous communities using stratified two-stage cluster sampling. Within each household, adults answered questions related to their dogs and their experiences with dog bites and aggression. A total of 328 households were interviewed, representing a participation rate of 90.9% (328/361) and 1,450 people. Approximately 65.2% of the households owned one or more dogs, with a mean of 1.3 (SD=1.5) and 2.0 (SD=1.5) owned dogs in all participant households and dog-owning households, respectively. The human: owned dog ratio for all participant households was 3.4:1 (1450/428), and for the dog-owning households was 2.3:1 (984/428). The owned dog male: female ratio was 1.4:1 (249/179). Approximately 74.4% (95.0% CI=69.8% - 78.7%) of the owned dogs were older than one year (mean age: 2.9 years; SD=2.5). The mean age of owned female dogs at first litter was 1.9 years (SD=1.2) and the mean litter size was 4.2 puppies (SD=2.1). Approximately 36.9% (95.0% CI=31.8% - 46.4%) of the females were spayed, and 14.1% (95.0% CI=10.7% - 19.7%) of the males were neutered. Only 44.9% (95.0% CI=40.1% - 49.7%) were always confined when unsupervised. Approximately 84.4% (95.0% CI=80.6% - 87.7%) were reported to have been vaccinated against rabies in 2015. The knowledge of owned dog demography and ecology provided by this study can inform local government planning of dog population control interventions, and could serve as a baseline for the development of agent-based models to evaluate the effects of different dog population control strategies on dog demography.

Recombinant rabies virus expressing dog GM-CSF is an efficacious oral rabies vaccine for dogs

Developing efficacious oral rabies vaccines is an important step to increase immunization coverage for stray dogs, which are not accessible for parenteral vaccination. Our previous studies have demonstrated that recombinant rabies virus (RABV) expressing cytokines/chemokines induces robust protective immune responses after oral immunization in mice by recruiting and activating dendritic cells (DCs) and B cells. To develop an effective oral rabies vaccine for dogs, a recombinant attenuated RABV expressing dog GM-CSF, designated as LBNSE-dGM-CSF was constructed and used for oral vaccination in a dog model. Significantly more DCs or B cells were activated in the peripheral blood of dogs vaccinated orally with LBNSE-dGM-CSF than those vaccinated with the parent virus LBNSE, particularly at 3 days post immunization (dpi). As a result, significantly higher levels of virus neutralizing antibodies (VNAs) were detected in dogs immunized with LBNSE-dGM-CSF than with the parent virus. All the immunized dogs were protected against a lethal challenge with 4500 MICLD₅₀ of wild-type RABV SXTYD01. LBNSE-dGM-CSF was found to replicate mainly in the tonsils after oral vaccination as detected by nested RT-PCR and immunohistochemistry. Taken together, our results indicate that LBNSE-dGM-CSF could be a promising oral rabies vaccine candidate for dogs.

Free-Roaming Dogs in Nepal: Demographics, Health and Public Knowledge, Attitudes and Practices

In Nepal, most dogs are free to roam and may transmit diseases to humans and animals. These dogs often suffer from malnutrition and lack basic health care. Minimal information is available about their demographics and about public attitudes concerning dogs and diseases. We carried out a study in Chitwan District (central Nepal), to collect baseline data on free-roaming owned dog demographics, assess knowledge, attitudes and practices of dog owners concerning dogs and rabies, evaluate rabies vaccination coverage and anthelmintic treatment of dogs, measure dogs' response to rabies vaccination and assess dog health through body condition scores and parasites. We conducted household interviews with owners of free-roaming female dogs (n = 60) and administered dogs with rabies vaccination and anthelmintics. Dog owners regularly fed free-roaming dogs but provided minimal health care; 42% of respondents did not claim ownership of the dog for which they provided care. We collected skin, faecal and blood samples for parasite identification and for measuring rabies virus-specific antibodies. Ninety-two per cent of dog owners were aware of the routes of rabies virus transmission, but only 35% described the correct post-exposure prophylaxis (PEP) following a dog bite. Twenty-seven per cent of the dogs had measurable rabies virus-specific antibody titres and 14% had received anthelmintics in the previous year. Following rabies vaccination, 97% of dogs maintained an adequate antibody titre for ≥6 months. Most dogs appeared healthy, although haemoprotozoans, endoparasites and ectoparasites were identified in 12%, 73% and 40% of the dogs, respectively. Poor skin condition and parasite load were associated. Seventy-four per cent of the females had litters in 1 year (mean litter size = 4.5). Births occurred between September and February; we estimated 60% mortality in puppies. We concluded that vaccination coverage, PEP awareness and anthelmintic treatment should be emphasized in educational programmes focussed on animal welfare, veterinary and public health.

Population Estimation Methods for Free-Ranging Dogs: A Systematic Review

The understanding of the structure of free-roaming dog populations is of extreme importance for the planning and monitoring of populational control strategies and animal welfare. The methods used to estimate the abundance of this group of dogs are more complex than the ones used with domiciled owned dogs. In this systematic review, we analyze the techniques and the results obtained in studies that seek to estimate the size of free-ranging dog populations. Twenty-six studies were reviewed regarding the quality of execution and their capacity to generate valid estimates. Seven of the eight publications that take a simple count of the animal population did not consider the different probabilities of animal detection; only one study used methods based on distances; twelve relied on capture-recapture models for closed populations without considering heterogeneities in capture probabilities; six studies applied their own methods with different potential and limitations. Potential sources of bias in the studies were related to the inadequate description or implementation of animal capturing or viewing procedures and to inadequacies in the identification and registration of dogs. Thus, there was a predominance of estimates with low validity. Abundance and density estimates carried high variability, and all studies identified a greater number of male dogs. We point to enhancements necessary for the implementation of future studies and to potential updates and revisions to the recommendations of the World Health Organization with respect to the estimation of free-ranging dog populations.

Single-layer tungsten oxide as intelligent photo-responsive nanoagents for permanent male sterilization

Permanent male sterilization has been recognized as useful tools for the development of neuter experimental animals and fattening livestock, as well as efficient control of pet overpopulation. Traditional routes such as surgical ways, chemical injections, and anti-fertility vaccines have addressed these crucial problems with idea outcomes. However, these routes usually bring out serious pain and infection towards animals, as well as induce long-term adverse reaction and immune suppression. Thus, a convenient, but non-surgical strategy for male sterilization under a mild manner is highly desirable. Here, for the first time, we demonstrate a novel platform for male sterilization by using single-layer WO2.72 nanosheets as smart photo-responsive sterilants. Upon a 980 nm irradiation, these nanoagents can possess intrinsic NIR-induced hyperthermia and sensitize the formation of singlet oxygen due to the cooperation of photothermal and photodynamic effects. Mechanism of cellular injury can be attributed to the denaturation of protein and apoptosis-related death. Moreover, long-term toxicity and possible metabolism route after testicular injection are discussed, indicating the neglectable systemic toxicity and high bio-compatibility of our nanoagents. Overall, our strategy can extremely overcome the shortcomings in various routine routes and suggest the new biological application of nanomaterials.

Ovarian blood vessel occlusion as a surgical sterilization method in rats

PURPOSE

To evaluate the female sterilization by occlusion of the ovarian blood flow, using the rat as experimental model.

METHODS

Fifty-five females rats were divided into four groups: I (n=10), bilateral ovariectomy, euthanized at 60 or 90 days; II (n=5), opening the abdominal cavity, euthanized at 90 days; III (n=20), bilateral occlusion of the ovarian blood supply using titanium clips, euthanized at 60 or 90 days; and IV (n=20), bilateral occlusion of the ovarian blood supply using nylon thread, euthanized at 60 or 90 days. The estrous cycle was monitored by vaginal cytology. After euthanasia, the reproductive tissues were evaluated histologically.

RESULTS

Ovarian atresia was identified macroscopically at 60 days after surgery in the rats in groups III and IV; however, most of the rats in group III maintained cyclicity. Histology of the tissues from group IV revealed that the ovarian tissue was replaced by dense fibrous connective tissue that was slightly vascularized and that intact follicles were absent by 90 days.

CONCLUSION

Ovarian blood vessels occluded caused ischemia, leading to progressive tissue necrosis, and bilateral occlusion using a nylon ligature is a viable method for surgical sterilization.

Fertility control to mitigate human–wildlife conflicts: a review

As human populations grow, conflicts with wildlife increase. Concurrently, concerns about the welfare, safety and environmental impacts of conventional lethal methods of wildlife management restrict the options available for conflict mitigation. In parallel, there is increasing interest in using fertility control to manage wildlife. The present review aimed at analysing trends in research on fertility control for wildlife, illustrating developments in fertility-control technologies and delivery methods of fertility-control agents, summarising the conclusions of empirical and theoretical studies of fertility control applied at the population level and offering criteria to guide decisions regarding the suitability of fertility control to mitigate human–wildlife conflicts. The review highlighted a growing interest in fertility control for wildlife, underpinned by increasing numbers of scientific studies. Most current practical applications of fertility control for wild mammals use injectable single-dose immunocontraceptive vaccines mainly aimed at sterilising females, although many of these vaccines are not yet commercially available. One oral avian contraceptive, nicarbazin, is commercially available in some countries. Potential new methods of remote contraceptive delivery include bacterial ghosts, virus-like particles and genetically modified transmissible and non-transmissible organisms, although none of these have yet progressed to field testing. In parallel, new species-specific delivery systems have been developed. The results of population-level studies of fertility control indicated that this approach may increase survival and affect social and spatial behaviour of treated animals, although the effects are species- and context-specific. The present studies suggested that a substantial initial effort is generally required to reduce population growth if fertility control is the sole wildlife management method. However, several empirical and field studies have demonstrated that fertility control, particularly of isolated populations, can be successfully used to limit population growth and reduce human–wildlife conflicts. In parallel, there is growing recognition of the possible synergy between fertility control and disease vaccination to optimise the maintenance of herd immunity in the management of wildlife diseases. The review provides a decision tree that can be used to determine whether fertility control should be employed to resolve specific human–wildlife conflicts. These criteria encompass public consultation, considerations about animal welfare and feasibility, evaluation of population responses, costs and sustainability.