The most common cause of infertility in dogs and cats is related to husbandry problems (timing, techniques, male selection). Breeding with a proven fertile male must occur at the optimal time for the female. Infectious, anatomical, metabolic, and functional problems associated with infertility occur less frequently.
Canine brucellosis is a highly contagious disease caused by Brucella canis, resulting in abortion in bitches and infertility associated with orchitis and epididymitis in males. Neutered dogs can be infected and display diskospondylitis, osteomyelitis, uveitis, and lymphadenitis. Effective therapy does not exist. Brucellosis is a zoonotic disease.
Other infectious causes of infertility in the bitch include the following:
minute virus
Cryptosporidium
opportunistic bacterial infections: Escherichia coli, Salmonella
In queens, infectious causes of infertility include the following:
feline herpesvirus
opportunistic bacterial infections: Campylobacter, Salmonella, E coli, Streptococcus spp
These infections may cause abortion, neonatal death, fetal resorption, and apparent infertility.
Anatomical causes of infertility include acquired and congenital problems.
Fibrosis of the oviducts or uterine horns, probably a result of inflammation after infection or trauma, leads to infertility. Similarly, bilateral obstruction of the sperm ducts can cause azoospermia and infertility.
High environmental temperature and excessive conditioning resulting in increased body temperature can induce either temporary or permanent azoospermia. Kennel or cattery management should allow for breeding males to remain cool during the summer.
Scrotal dermatitis can also lead to infertility.
Metabolic causes of infertility, other than in severely ill individuals, are rare. Hypothyroidism has no effect on male libido or semen quality. Hypothyroid female dogs may have prolonged interestrous intervals.
Prolonged estrus in the bitch can be caused by estrogen-producing ovarian cysts, functional ovarian tumors, or exogenous estrogens (including human transdermal hormone replacement therapy). Exogenous hormones should be discontinued. Laparotomy with histological examination is usually indicated, because medical attempts at inducing ovulation (with human chorionic gonadotropin, follicle-stimulating hormone, GnRH) are usually unrewarding.
Prolonged diestrus in the bitch can result from luteal cysts or a progesterone-producing ovarian tumor. Medical manipulation with prostaglandins is usually unrewarding, and ovariectomy with histological examination is indicated.
Epididymitis and orchitis in dogs should always prompt evaluation for brucellosis but can be secondary to other bacteria, most commonly E coli. Usually the entire genitourinary tract is involved. Semen quality is usually markedly impacted.
Canine prostatitis (bacterial) can be subclinical and contribute to subfertility and infertility, primarily by impacting semen quality (see bacterial prostatitis ultrasonogram).
Courtesy of T. W. Baker.
Benign prostatic hyperplasia does not affect fertility but results commonly in hemospermia, a benign condition except for making semen cryopreservation unsuccessful, because hemoglobin interferes with membrane stability in the freeze/thaw process.
Cystic benign prostatic hyperplasia is nonmalignant, with hemospermia resulting; however, it may predispose the dog to bacterial colonization of the cysts and result in septic prostatitis.
Benign prostatic hyperplasia and cystic benign prostatic hyperplasia can be treated successfully with finasteride (1–5 mg, PO, every 24 hours).
Rarely, prostatic hyperplasia causes clinical discomfort. The volume of prostatic fluid will diminish with finasteride; the use of semen extenders may be indicated. See ultrasonographic images of benign hyperplasia, transverse and sagittal views.
Courtesy of T. W. Baker.
Courtesy of T. W. Baker.
Prostatic neoplasia is a serious condition, usually causing marked clinical signs (pain, dysuria, tenesmus) and impacting fertility.
Testicular neoplasia, sometimes functional and producing estrogen, can cause infertility. Unilateral gonadectomy of the affected testis may allow the other testis to regain its ability to produce sperm, but the prognosis is guarded.
