Overview of Infertility in the Bitch
Dogs are the most common pet animals and being used as companion, shows, assistance for old people, as models for wildlife conservation. There is reported 80-90% fertilization in canines but infertility is still a deep topic to understand. These are the individual breeder or owner’s expectations and yet not been understood very well. Now more studies and use of ultrasound in pet animals led to understanding this very well.
- Ovarian Agenesis: It is rare and ovaries are not formed, lead to infertility if both ovaries are not present
- Segmental aplasia of the Müllerian duct system: Tubular duct system is not formed if failure of the formation of the paramesonephric ducts occurs, which also lead to absence of a uterine horns. Also, if failure of fusion of the caudal paramesonephric ducts occurs, which lead to duplication of the uterus (didelphus) or cranial vaginal septation; or a failure of the caudal paramesonephric ducts to fuse properly with the urogenital sinus, resulting in imperforate hymen
- Intersex: Intersex animals have ambiguous genitalia. In the bitch, this is usually recognised because of an abnormal phenotypic sex appearance; externally, the animal appears female, but when it reaches puberty, the clitoris enlarges and male-like behaviour may develop. It is due to the abnormalities of: (1) chromosomes, (2) gonads, or (3) phenotype.
- Fröhlich’s syndrome: Acquired atrophy of the genitalia has been seen with neoplasia of the hypothalamus or pituitary. It is a rare condition.
- Cystic endometrial hyperplasia: Cystic endometrial hyperplasia, which precedes pyometra as a clinical disease, may cause infertility by allowing the development of a mating-induced endometritis resulting in conception failure and embryonic resorption. High progesterone and infection like E. Coli cause this hyperplasia in luteal phase and characterized by brown color discharge with odour.
- Neoplasia: Ovarian tumors are uncommon in bitch around 1% and is found more in aged dogs 8 years. Granulosa cell tumors are most important lead to signs of ascites. The diagnosis of ovarian tumours is usually made on the basis of clinical signs, abdominal palpation, radiography, and ultrasonography.
The transmissible venereal tumour (TVT) affects the vagina and external genitalia of the bitch and the penis of the dog. Transmission of the tumour occurs at coitus when infected cells ‘seed’ the genital mucosa of the recipient. The use of surgical debulking and various chemotherapeutic regimes has been described, including cyclophosphamide and vincristine, and radiation therapy.
- Delayed Puberty and Prolonged Anoestrus: The age of puberty in the bitch ranges between 5 and 24 months, although this is influenced by breed, body weight, and environmental conditions. Bitches that do not reach puberty by 2.5 years of age are therefore considered to have delayed puberty. Because it is not uncommon for there to be few signs associated with the first oestrus, bitches that are thought to have delayed puberty may simply have had an unobserved oestrus. Failure to identify oestrus should also be considered in bitches that have prolonged interoestrous intervals. A high peripheral plasma progesterone concentration (> 2.0 ng/mL/ 6.5 nmol/l) demonstrates that ovulation has occurred within the last 60 days (i.e., a recent oestrus has been missed). The normal interoestrous interval is between 26 and 36 weeks.
- Silent Oestrus: Normal cyclical endocrine changes may occur in some bitches without obvious external signs of prooestrus or oestrus. It is possible that oestrous events are not observed by the owner because there is only slight vulvar swelling and minimal serosanguineous discharge or because the bitch is particularly fastidious. On some occasions, overt pseudopregnancy occurs in the absence of a preceding observed oestrus. However, ovulation can be confirmed by the measurement of peripheral plasma progesterone concentrations. If suspected, oestrus can be detected by the weekly examination of exfoliative vaginal cytology.
- Split Oestrus: Occasionally, and most commonly at their first oestrus, bitches develop vulvar swelling and a serosanguineous vulvar discharge of a short duration. However, ovulation does not occur; follicles presumably regress and the signs of proestrus disappear. A normal oestrus follows several weeks later. If the split oestrus (false oestrus) syndrome is recognised, it is important to ensure that mating occurs at the correct time in relation to ovulation. In some cases, the initial or subsequent oestrus is prolonged, and here induction of ovulation may be attempted using human chorionic gonadotrophin (hCG), although it can be difficult to be certain when to administer this preparation. This is most successful when administered at the peak of vaginal epithelial cell cornification. Occasionally, a split oestrus is not recognised, and the return to oestrus is mistaken for pyometra because of the development of a vulvar discharge.
- Prolonged Proestrus/Oestrus: The normal interval between the onset of proestrus and ovulation varies from 5 to 30 days. However, most bitches ovulate by Day 14 after the onset of proestrus, and those that ovulate later than this are often considered to have prolonged oestrus
- Ovarian Cysts: Cystic follicles and CL are very rare in the bitch. True oestrogen-secreting follicular cysts produce persistent oestrus with vulvar discharge, and after several months, there may be flank alopecia and hyperkeratosis. Ultrasonographically, large fluid-filled follicles may be identified but must be carefully differentiated from normal follicles and early CL, both of which have central fluid filled cavities. Some follicular cysts can be induced to luteinise by alternate day administration of hCG on three occasions. In others, such treatment does not succeed, but the cysts may respond to progestogen administration using hormones such as megestrol acetate. With the latter, there is an increased risk of pyometra because the progestogen is administered after a prolonged period of oestrogen priming. Ovariectomy may be necessary in cases that do not respond to exogenous hormone therapy. Scientist suggested that they may secrete progesterone and produce prolonged anoestrus (sic) and cystic endometrial hyperplasia; in some cases, this may progress to pyometra
- Habitual Abortion: There is little evidence to suggest that habitual abortion is a clinical problem in the majority of breeds of dog, with the exception of the German Shepherd, in whom inadequate luteal function has been documented. Cases of abortion and resorption with normal progesterone concentrations are commonly documented using real-time B-mode ultrasound. Most cases of abortion are probably related to an abnormal uterine environment (cystic endometrial hyperplasia), fetal defects, and/or the result of infectious agents.
- Infectious: Agents like Brucella canis, Herpesvirus, Parvovirus, Toxoplasma gondii are related to various infertility problems.
Abhishek Bhardwaj1*, Nakul Gulia2, Akshay Kumar3
Ph.D. Scholar 1*, M. V. Sc. Scholar 2, Department of Veterinary Gynecology and Obstetrics, GADVASU, Ludhiana, Punjab, Ph.D. Scholar Division of Veterinary Surgery and Radiology, IVRI, Bareilly, U. P.
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