Causes and Prevention Methods of Infertility in Male Dogs
Infertility in male dogs refers to the inability of a male dog to fertilize, or the inability of its sperm to fertilize an egg: there are many types of infertility, including primary infertility, low fertility, and acquired infertility.
Among primary infertility, the most common is testicular hypoplasia, with the testes being smaller in size and hard or soft in texture. Most affected dogs have normal libido but no sperm. In animals with segmental dysplasia of both epididymides, the ejaculatory reflex is normal, but the ejaculate contains no sperm. Low fertility usually refers to conditions such as a reduced sperm count, a normal sperm count but extremely poor motility, or a large number of abnormal sperm. The sperm of dogs with low fertility either have a proximal cytoplasmic droplet, a detached head, or tail or acrosome abnormalities. When the rate of any one type of abnormality exceeds 20%, fertility is reduced. The causes of acquired infertility are more complex, such as:
(1) Heat stress: when the temperature of the testes rises to equal body temperature, the sperm within them lose their motility, and if this lasts a little longer, the testes lose their spermatogenic capacity.
(2) Local ischemia: when torsion of the testis occurs, the blood supply to the testis is greatly reduced, causing severe ischemia and thereby affecting the spermatogenic capacity of the testis. In addition, reduced arterial perfusion of the testis, even for a relatively short time, can damage more than half of the cells that produce testosterone.
(3) Autoimmunity: when the testis is injured, sperm leak out, causing the autoimmune system to produce antibodies, which sensitize white blood cells and trigger a local immune response. The binding of antigen and antibody greatly reduces fertilizing capacity.
(4) Chemical poisoning: for example, zinc can cause severe necrosis of testicular interstitial cells and seminiferous tubules: drugs such as alpha-chlorohydrin and alkylating compounds (chlorambucil, phosphoramide) can cause pathological changes in the testes and epididymides: amphotericin B, estrogens, and anti-estrogens can cause testicular atrophy: antitumor mitotic agents such as phosphoramide and vinblastine can inhibit testicular cell division.
(5) Hormonal imbalance: in hyperthyroidism, the spermatogenic capacity of the testes declines; changes in adrenal steroid hormone levels can affect the function of the pituitary and testes: tumors of the hypothalamus or pituitary. Reduced production and release of gonadotropins can cause testicular degeneration and atrophy.
(6) Scrotal dermatitis: the scrotal skin of dogs is very sensitive, and trauma or chemical irritation easily causes inflammation. Scrotal dermatitis can lead to sperm abnormalities, such as poor motility and an increased number of sperm with coiled tails and ring-shaped heads.
(7) Excessive mating can reduce fertility.
(8) Changes in the environment can have a reversible adverse effect on the fertility of male dogs.
(9) Tumors: seminomas, Sertoli cell tumors, and interstitial cell tumors can all reduce the spermatogenic capacity of the testes.
(10) Obstruction of the testicular ducts: it occurs frequently in orchitis and epididymitis.
(11) Age: that is, senile infertility. The diagnosis of infertility includes history taking and general examination, semen quality examination, testicular biopsy, hormone testing, observation of sexual behavior, and so on. Treatment of infertility: for those with reproductive organ disease and/or systemic disease, corresponding treatment should be given for the primary disease; congenital infertility and senile infertility generally have no treatment value, and except for rare breeds, are generally culled; for infertility caused by feeding and management, feeding and management can be improved, exercise increased, and a nutritionally adequate and balanced diet provided; for infertility caused by poor semen quality, impotence, and so on, in addition to strengthening feeding and management and taking corresponding measures according to the cause, testosterone, pregnant mare serum gonadotropin, or human chorionic gonadotropin and other treatments may be tried according to the condition.