The bitches are classified as seasonal monoesters species. In particular periods
of the year, they exhibit 1-2 estruses. This frequency is typically influenced
by specific factors like the breed, geographical position and management condition
which are the most important ones (Christiansen, 1984).
Typically in Albania, bitches exhibit two oestrus seasons in spring (March up to May) and in the entry of the autumn (September up to October). Some dog owners avoid the demonstration of their dogs oestrus. Therefore, they try to limit dogs reproduction activity. Also due to other effects, it is sometimes necessary to limit dogs reproduction activity.
The bitchs reproduction activity can be limit through surgical intervention
(ovaryhysteroectomy) which consists in the definitive interruption of reproductive
activity. Additionally, the reproductive activity can be limit in conservative
(medical) way (Sokolowski et al., 2001).
Another method consists in using of different natural or synthetic hormonal substances (mainly steroids) in order to inhibit to delay or cancel the oestrus without damaging the reproductive activity for the future. In bitches, the oestrus cycle is quite long compared with the others animals lasting about 6 months. Any phase of the cycle has different hormonal profile.
The progesterone is the main hormone of the cycle. It starts to increase from
yellow body in the end of pro-estrum (from luteinised follicles) during the
oestrus and metoestrum. During the anoestrus phase, the level of progesterone
is under basal level (<0.1 ng mL•1) (Morrow,
1986). The external injection of progesterone during this phase can cause
anti-gonadotrops effect. The inhibition of production of FSH and LH hormones
causes the interruption of follicles development and therefore, the interruption
of the estrus.
The treatment of bitches during pro-estrus or at the beginning of the estrus delay temporary the estrus exhibition. While its application during anoestrus inhibit the estrus for a long time depending of the substance and the purpose of its use. The clinical signs and the histological changes of genital tract are necessary for determination of the optimal moment of the progesterone use.
Every phase has clear clinical signs. However, laboratory test of vaginal cytology
is very helpful for their determination, especially during anoestrus phase.
The laboratory technique consist of detections of histological changes in vaginal
tract during the cycle phases under influence of different hormones concentrations
that circle in blood principally of 17-• Estradiol (Morrow,
1986; Fayrer-Hosken, 1996; Feldman
and Nelson, 2004). Histological changes can be examined in vaginal mucus
and according of its cells type, there can determine the exist cycle phase of
MATERIALS AND METHODS
This study was realised in some private clinics of Tirana district during the time period 2007-2009.
|| The evaluation of cycle phases through vaginal cytology in
bitches (Christiansen, 1984)
Animals: Sixteen bitches clinically healthy mixed-bred bitches, aged 2-6 years, weighing between 10 and 35 kg were selected for this study. The determination of cycle phase was performed through anamnesis, clinical control, vaginal examination and vaginal cytology.
Vaginal cytology: Researchers took samples from vagina. The samples of cytological examination were taken through a sterile cotton swab in the deepness of vagina. After their spread on the lama, fixation, dryness and dyeing was preformed their microscopic examination for evaluation of the vaginal cells. Their examination consisted on evaluation of vaginal cells.
Hormonal treatment: The bitches were treated with Proligestone (Covinan®,
Intervet) in doses 2 mg kg•1 or 0.1 mL kg•1
weigh. The oestrus inhibitory effects were evaluated through the calculation
of times, days from treatment time until next cycle.
RESULTS AND DISCUSSION
Cytology examination of the smear is one of the important in connection with
the gynaecological investigation of the bitch. Analysis of the epithelial cell
content of the vaginal secretion is used to demonstrate the stage of the cycle
and the optimum time for hormonal treatment or mating and artificial insemination.
All bitches were found to be in anestrous phase since microscopic analysis showed
the presence of a few basal-cells, parabasal and intermediate cells and a few
leukocytes. Treatment of the bitches in this phase of the cycle helps for delaying
the next phase. Findings on vaginal cytology were compared with that of Christiansen
(1984) (Table 1). The aim of this study is the quantification
of the effect of the treatment with Proligestone (Covinan®, Intervet)
for the purpose of limiting dogs reproduction activity. The time of treatment
is calculated with reference to the 1st day of treatment until the 1st day of
|| The records of hormonal treatment of experimental bitches
The results of the study are shown in Table 2. The extreme
limits of the oestrus change from 175-206 days. The Proligeston effects for
the inhibition of the oestrus in the experiment bitches are compatible with
the literature data (Schaefers-Okkens, 1996). The mechanism
of action of the hormonal substance used by us progesterone is explained with
its ability to inhibit the hypotalamo-hypophisis axis. This effect inhibits
the ovary activity and the manifestation of the oestrus. The experimental treated
animals did not exhibit side effects from the treatment. Nevertheless, the hormonal
treatment should not be repeated more than twice one after the other.
The bitches should be examined for different pathologies as breast tumours or infections of genital tract. The cytology of vaginal mucus is an efficient method for determination of the cycle phases in bitches. The regular hormonal treatment (progesterone) during anoestrus inhibits the oestrus about 190±14 day•1. The inhibition period of the oestrus has the tendency to be longer in young bitches even the statistical analyses do not confirm this tendency. It is not advisable that the bitches should be treated twice with progesterone preparations for the oestrus control. The frequent treatment can cause increase of the weight, hair drop and other major side effects.