Cryptorchidism in Dogs: Management Guide

Comprehensive guide to cryptorchidism in dogs: causes, diagnosis (AMH, hCG, ultrasound), surgical removal, risks (Sertoli cell tumor), long‑term care and owner guidance.

Quick Overview

• What it is: Cryptorchidism (retained testicle[s]) is failure of one or both testicles to descend into the scrotum by an appropriate age. Retention can be in the inguinal canal (inguinal cryptorchidism) or inside the abdomen (abdominal cryptorchidism).
• Who’s at risk: Certain breeds (small and toy breeds, some terriers and spaniels) and individual dogs with a family history. Cryptorchidism is heritable and should not be passed on by breeding affected dogs.
• Prognosis: Excellent with timely surgical removal (orchiectomy / cryptorchidectomy). Retained testes have a higher risk of neoplasia (Sertoli cell tumor, seminoma) and torsion, so removal is recommended even if only one testicle is affected.

Pathophysiology — explained simply

Before birth and during early postnatal life, the testes form near the kidneys and descend through the inguinal canal into the scrotum under hormonal (testosterone, insulin-like factor 3), gubernacular, and mechanical influences. Cryptorchidism results when this descent fails. A retained testicle continues to produce hormones and may remain functional (secreting testosterone); retained testicles are exposed to higher abdominal temperatures, which impairs spermatogenesis and increases the long-term risk of testicular disease.

Types:

• Unilateral cryptorchidism: one testicle retained, the other in the scrotum. Fertility is usually preserved but the dog should not be bred.
• Bilateral cryptorchidism: both testicles retained — typically results in infertility.
• Location: inguinal (closer to the scrotum) or abdominal (more proximal). Abdominally retained testes have higher complication and tumor risk.

Breed-specific risk factors and prevalence

Cryptorchidism occurs across breeds but is most commonly reported in small and toy breeds and some terriers. Breeds with increased prevalence reported in the literature include:

• Chihuahuas, Yorkshire Terriers, Pomeranians, Toy Poodles (small breeds)
• Miniature Schnauzers, Boston Terriers
• Some lines of Boxers and other working breeds may also show familial clustering

Sources: ACVS client information and peer-reviewed veterinary reproduction texts (see citations).

Signs and stages

Common signs depend on whether the condition is unilateral or bilateral:

• Visible: an empty or smaller-than-expected scrotum on one or both sides
• Palpable: an inguinal retained testicle may be felt as a firm, small mass in the groin
• Non-specific: some dogs have no outward signs beyond empty scrotum
• Complications: abdominal pain, vomiting or acute signs if testicular torsion occurs; feminization (gynaecomastia, attraction of male dogs) if Sertoli cell tumor produces estrogen

Diagnostic approach

Goals: confirm presence/absence of testicular tissue and locate retained testes prior to surgery.

History and physical exam

• Palpation of scrotum and inguinal region is first-line. Many inguinal testes are palpable; abdominal ones often are not.

• Anti-Müllerian hormone (AMH) assay: AMH is produced by Sertoli cells and is highly sensitive and specific for the presence of testicular tissue. A single blood sample sent to a qualified lab can often confirm whether any testicular tissue is present.
• hCG stimulation test: baseline testosterone, administer hCG (human chorionic gonadotropin), then measure testosterone 60–120 minutes later. A rise in testosterone indicates functional testicular tissue. Protocols vary; typical practical dosing ranges are 250–1,000 IU IM (size-dependent) but follow your veterinarian’s or laboratory protocol. hCG testing requires serial blood draws and has more logistical complexity than AMH.

• Ultrasound: first-line imaging to locate retained testes in the inguinal region or abdomen. Sensitivity is operator-dependent; small or atrophic testes may be hard to visualize.
• Advanced imaging: CT or MRI can be used for difficult cases but are rarely necessary.
• Diagnostic laparoscopy: both diagnostic and therapeutic — direct visualization of abdominal cavity and ability to remove retained testicle(s) laparoscopically.

• Referral to a board-certified veterinary surgeon or reproductive specialist is advised when localization is uncertain, when prior surgery failed to locate testes, or when advanced techniques (laparoscopy) are being considered.

Why retained testicles must be removed

Key reasons to remove retained testicles:

• Neoplasia risk: Retained testes have an increased risk of testicular tumors, particularly Sertoli cell tumors and seminomas. While reported rates vary by study and population, retained testes show a several-fold higher incidence of neoplasia compared with scrotal testes. Sertoli cell tumors can produce estrogen, causing feminization, bone marrow suppression and other systemic problems.
• Testicular torsion: Retained testes are more prone to torsion, which causes acute, severe abdominal pain and is an emergency.
• Infertility and heat stress: Retained testes do not usually produce viable sperm because of higher internal temperatures; removal eliminates ongoing poor spermatogenesis.
• Genetics: Cryptorchidism is heritable. Removing affected dogs from breeding reduces transmission to future generations.

Treatment options

Surgical

• Standard recommendation: surgical removal of retained testicle(s) — cryptorchidectomy. For unilateral cryptorchidism, this typically includes removal of the contralateral scrotal testis (bilateral orchiectomy) to prevent breeding.
• Approach:

• Intraoperative considerations: careful dissection to avoid hemorrhage from spermatic vessels; identification and removal of the entire testis and epididymis; submission of tissues for histopathology to detect occult neoplasia.

• There is no reliable medical treatment to correct an established cryptorchidism in dogs. Hormonal induction of descent (e.g., hCG, GnRH analogs) has been attempted in young animals with variable success and is not routinely recommended as an alternative to surgery. These treatments are less reliable and do not remove the risk of malignancy if descent occurs late or partial.

• Laparoscopic cryptorchidectomy is increasingly common and preferred for abdominal retained testes by many surgeons. It is both diagnostic and therapeutic.

• Pre-operative bloodwork (CBC, chemistry) is recommended. Imaging or hormonal testing as above.
• Analgesia: multimodal analgesia (opioids perioperatively — e.g., hydromorphone, methadone IV/IM as per vet dosing; non-steroidal anti-inflammatory drugs post-op such as carprofen 2.2 mg/kg PO q12–24 h or meloxicam 0.1 mg/kg PO q24 h, adjusted by clinician) — follow your vet for exact dosing and contraindications.
• Antibiotics: not routinely required for elective cryptorchidectomy unless contamination, concurrent disease, or surgeon preference (perioperative cefazolin 20 mg/kg IV is commonly used when indicated).

Long-term management and monitoring

• Histopathology: Always submit removed testicle(s) for histopathology to detect occult tumors.
• Recovery: rest and limited activity for 10–14 days, monitor incision for swelling, drainage or dehiscence, and keep E-collar until sutures/staples are removed or healed.
• Behavior and hormones: removal of testes eliminates most testosterone-driven behaviors over time; if problem behaviors persist, discuss behavior modification and targeted medical therapy with your vet.
• Reproductive advice: do not breed cryptorchid dogs or their close relatives.
• Follow-up: if histopathology reveals neoplasia, your vet or oncologist will advise on staging (chest radiographs, lymph node evaluation) and additional treatment if needed.

Prognosis and quality of life

• Prognosis after appropriate surgical removal is excellent. Most dogs recover without lasting complications, maintain normal quality of life, and experience decreased risk of testicular neoplasia going forward.
• If a retained testicle has developed a tumor (e.g., Sertoli cell tumor) prognosis depends on tumor type, size, metastasis and whether systemic effects (e.g., bone marrow suppression from estrogen) occurred prior to removal. Early removal improves outcomes.

Living With Cryptorchidism — practical daily tips

• If your dog is awaiting surgery:

• Post-op care:

• Lifestyle:

When to See Your Vet Urgently

Seek immediate veterinary attention if your dog has:

• Sudden onset of severe abdominal pain, pacing, restlessness, vomiting (possible testicular torsion)
• Rapidly enlarging inguinal swelling or scrotal swelling with pain
• Lethargy, pale gums, bleeding or signs of systemic illness (possible estrogenic effects from Sertoli cell tumor)
• Persistent fever, incision bleeding, or wound dehiscence after surgery

This guide is for educational purposes. Always consult your veterinarian for diagnosis and treatment.

References and further reading

• American College of Veterinary Surgeons (ACVS) client information – Cryptorchidism: https://www.acvs.org/small-animal/cryptorchidism
• Tobias, K.M., Johnston, S.D. (2012). Veterinary Surgery: Small Animal Expert Consult. (textbook chapters on cryptorchidism and orchiectomy).
• Johnston, S.D., Root-Kustritz, M.V., Olson, P.N.S. (2001). Canine and Feline Theriogenology (reproductive medicine chapters).
• Peer-reviewed reviews on AMH and hCG testing in dogs (veterinary reproduction journals) — AMH has high sensitivity and specificity for identifying testicular tissue and is increasingly preferred for ambiguous cases.

Frequently Asked Questions