Testicular Torsion

Testicular torsion is an acute, painful condition characterized by rotation of the spermatic cord, leading to obstruction of testicular blood flow, ischemia, and potential necrosis of the testicle. It is a surgical emergency in veterinary medicine, most commonly reported in dogs, with rare occurrence in cats. The condition can affect either a scrotal testis or, more frequently, an undescended (cryptorchid) testis, where the torsion occurs within the abdominal cavity or inguinal canal. The rotation compromises the pampiniform plexus (venous drainage) and testicular artery (arterial supply), resulting in venous congestion, arterial occlusion, and eventual infarction. The severity of clinical signs depends on the degree of rotation (90° to 720°) and the duration of torsion. Early diagnosis and surgical intervention (orchiectomy or detorsion with fixation) are critical to preserve fertility and prevent systemic complications such as peritonitis or endotoxemia.

The exact cause of testicular torsion is often idiopathic, but several predisposing factors have been identified. In dogs, torsion most commonly occurs in cryptorchid testes, particularly those located in the abdomen, due to the increased mobility of the undescended testis and the lack of normal scrotal attachments. Trauma to the scrotum or abdomen can initiate rotation. Neoplasia, especially Sertoli cell tumors, seminomas, and interstitial cell tumors, can increase testicular weight and alter the normal suspensory apparatus, predisposing to torsion. Inguinal hernias or excessive mobility of the spermatic cord may also contribute. In some cases, vigorous exercise or breeding activity may trigger torsion. In cats, torsion is extremely rare but has been reported in both scrotal and cryptorchid testes, often associated with testicular neoplasia or trauma. Iatrogenic causes are uncommon but can occur during surgical manipulation.

Testicular torsion is a relatively uncommon condition in small animal practice. It is most frequently diagnosed in dogs, with a higher incidence in large-breed dogs such as German Shepherds, Golden Retrievers, and Labrador Retrievers, likely due to their higher prevalence of cryptorchidism. Cryptorchidism itself is a heritable condition, with an estimated incidence of 1% to 15% in dogs, and torsion occurs in approximately 10% of cryptorchid testes. The condition is typically seen in young to middle-aged dogs (1 to 5 years), but can occur at any age. There is no strong sex predilection since it affects males. In cats, torsion is exceedingly rare, with only a few case reports in the literature. Breed predispositions in cats are not well established. The condition is more common in intact males, as castration removes the testis and eliminates the risk. No significant geographic or seasonal variations have been reported.

The pathophysiology of testicular torsion involves a sequence of vascular and ischemic events. Initially, rotation of the spermatic cord causes partial or complete obstruction of the pampiniform plexus, leading to venous congestion and increased intratesticular pressure. As venous outflow is compromised, arterial inflow continues, causing the testis to swell and become edematous. If the torsion is not relieved, arterial occlusion occurs, resulting in ischemia and hypoxia. The testicular tissue is highly sensitive to ischemia; irreversible damage can occur within 4 to 6 hours of complete torsion. Cellular hypoxia leads to depletion of ATP, failure of the sodium-potassium pump, and accumulation of intracellular calcium, triggering cell death via necrosis and apoptosis. The release of reactive oxygen species and inflammatory mediators (cytokines, prostaglandins) exacerbates tissue injury. If torsion persists, hemorrhagic infarction and necrosis of the testis ensue, which can lead to scrotal or abdominal inflammation, peritonitis, and systemic signs of endotoxemia or sepsis. In cryptorchid torsion, the necrotic testis may become a nidus for infection or, rarely, torsion of a neoplastic testis can cause rapid growth and metastasis.

Intrinsic factors include cryptorchidism, which is the most significant risk factor, as undescended testes are more mobile and lack the normal scrotal ligament attachments. Testicular neoplasia, particularly Sertoli cell tumors, can increase testicular weight and alter the normal suspensory apparatus, predisposing to torsion. Large testicular size, as seen in some breeds, may also increase the risk. Extrinsic factors include trauma to the scrotum or abdomen, which can cause sudden rotation of the testis. Vigorous exercise, breeding activity, or excessive manipulation of the testis during examination may trigger torsion. Inguinal hernias can allow the testis to move into the inguinal canal, increasing the risk of torsion. Iatrogenic factors are rare but can occur during surgical procedures that involve excessive traction on the spermatic cord. Environmental stress and obesity may indirectly contribute by increasing intra-abdominal pressure.

Clinical signs of testicular torsion vary depending on the location (scrotal vs. cryptorchid) and duration. In scrotal torsion, the most common presentation is acute onset of severe pain, swelling, and erythema of the affected scrotal sac. The testis may be firm, enlarged, and painful on palpation. The dog may exhibit lameness, reluctance to move, and signs of systemic illness such as fever, lethargy, and anorexia. In some cases, the torsion may be intermittent, causing recurrent episodes of pain. In cryptorchid torsion, the signs are more vague and may include acute abdominal pain, vomiting, anorexia, and abdominal distension. The affected testis is not palpable externally, and the diagnosis is often delayed. Systemic signs such as fever, tachycardia, and dehydration may be present due to peritonitis or endotoxemia. In chronic cases, the testis may become atrophied or necrotic, and the animal may present with a non-painful abdominal mass. In cats, signs are similar but may be less pronounced.

Differential diagnoses for scrotal torsion include: 1) Orchitis and epididymitis (bacterial, viral, or fungal) – typically associated with fever, scrotal swelling, and pain, but may have a more gradual onset and respond to antibiotics; 2) Testicular neoplasia – may present as a painless mass, but can cause acute pain if hemorrhage or necrosis occurs; 3) Scrotal trauma – history of injury, bruising, and swelling; 4) Inguinal hernia – may present with a soft, reducible mass in the inguinal region; 5) Testicular abscess – localized infection with purulent discharge; 6) Spermatic cord hematoma – following trauma or surgery. For cryptorchid torsion, differentials include: 1) Acute pancreatitis – presents with vomiting, abdominal pain, and elevated lipase; 2) Intestinal obstruction – history of foreign body ingestion, vomiting, and lack of defecation; 3) Peritonitis – due to other causes such as gastrointestinal perforation; 4) Prostatitis or prostatic abscess – may cause abdominal pain and systemic signs; 5) Splenic torsion – acute abdominal pain and shock; 6) Renal calculi or pyelonephritis – may cause flank pain and hematuria. Definitive diagnosis requires imaging and surgical exploration.

The diagnostic approach begins with a thorough history and physical examination. In scrotal torsion, palpation of the scrotum may reveal a painful, enlarged testis, and the spermatic cord may be thickened. In cryptorchid torsion, abdominal palpation may reveal a painful mass. The following steps are recommended: 1) Complete blood count (CBC) and serum biochemistry to assess for inflammation, dehydration, and organ dysfunction. 2) Abdominal ultrasonography is the imaging modality of choice. In scrotal torsion, Doppler ultrasound can assess blood flow to the testis; absence of flow confirms torsion. In cryptorchid torsion, ultrasound may identify a mass in the abdomen or inguinal region, and Doppler can evaluate vascularity. 3) Radiography may be helpful in cryptorchid torsion to identify a soft tissue mass or signs of peritonitis (loss of abdominal detail). 4) If torsion is suspected, surgical exploration is indicated for definitive diagnosis and treatment. In cases where the testis is not viable, orchiectomy is performed. If the testis is viable and the animal is intended for breeding, detorsion and orchiopexy may be considered, but this is rarely successful in torsion due to the high risk of recurrence and ischemic damage.

Hematological findings may include leukocytosis with a left shift, neutrophilia, and toxic neutrophils, indicating inflammation or infection. In cases of peritonitis or endotoxemia, thrombocytopenia and prolonged clotting times may be observed. Serum biochemistry may show elevated liver enzymes (ALT, AST) due to hepatic hypoxia or inflammation, and elevated renal parameters (BUN, creatinine) if dehydration or sepsis is present. Electrolyte imbalances, such as hyperkalemia or hyponatremia, may occur. In cryptorchid torsion, serum testosterone levels may be elevated if the testis is functional, but this is not diagnostic. Urinalysis may reveal hematuria or proteinuria if there is concurrent urinary tract involvement. Vaginal cytology is not applicable in males. Testicular biopsy is not recommended in torsion due to the risk of spreading neoplastic cells or worsening ischemia. Histopathology of the removed testis is essential to confirm the diagnosis and identify any underlying neoplasia.

Abdominal ultrasonography is the most valuable imaging modality. In scrotal torsion, B-mode ultrasound may show an enlarged, hypoechoic testis with a heterogeneous parenchyma, and the epididymis may be enlarged. Color Doppler or power Doppler is crucial to assess blood flow; absence of flow in the testicular artery or pampiniform plexus is diagnostic of torsion. In cryptorchid torsion, the affected testis may be identified as a mass in the abdomen or inguinal region, with similar echogenicity changes. The surrounding fat may appear hyperechoic due to inflammation. Radiography may show a soft tissue mass in the abdomen or loss of abdominal detail, but is less specific. Computed tomography (CT) and magnetic resonance imaging (MRI) are rarely used but can provide detailed anatomical information, especially in complex cases. Vaginoscopy is not relevant in males.

Cytology of fine-needle aspirates from a scrotal testis may show necrotic debris, inflammatory cells, and possibly neoplastic cells if a tumor is present. However, aspiration is not recommended in suspected torsion due to the risk of hemorrhage and infection. Histopathology of the removed testis is the gold standard. Grossly, the testis may be dark red to black, swollen, and hemorrhagic. Microscopically, there is extensive coagulative necrosis of the seminiferous tubules, interstitial hemorrhage, and edema. The spermatic cord vessels may show thrombosis. If a neoplasm is present, the histopathological type (e.g., Sertoli cell tumor, seminoma, interstitial cell tumor) is identified. Special stains, such as immunohistochemistry for inhibin or cytokeratin, may be used to differentiate tumor types. In chronic torsion, the testis may be atrophied and fibrotic.

Treatment of testicular torsion is primarily surgical. In scrotal torsion, emergency orchiectomy of the affected testis is recommended to relieve pain and prevent systemic complications. If the testis is viable and the animal is a valuable breeding animal, detorsion and orchiopexy (fixation of the testis to the scrotal wall) may be attempted, but this is rarely successful due to the high risk of recurrence and ischemic damage. In cryptorchid torsion, exploratory laparotomy is required to locate the affected testis and perform orchiectomy. Preoperative stabilization is essential: intravenous fluids (e.g., lactated Ringer's solution at 10-20 ml/kg/h) to correct dehydration and maintain blood pressure, and analgesics (e.g., opioids such as morphine 0.5-1 mg/kg IM or IV, or buprenorphine 0.01-0.02 mg/kg IV) for pain management. Broad-spectrum antibiotics (e.g., amoxicillin-clavulanate 20 mg/kg IV q8h, or cefazolin 22 mg/kg IV q8h) are indicated if there is evidence of infection or peritonitis. In cases of severe systemic illness, supportive care with antiemetics (e.g., maropitant 1 mg/kg SC q24h) and gastroprotectants (e.g., omeprazole 1 mg/kg IV q24h) may be needed. Postoperatively, the animal should be monitored for signs of peritonitis, and pain management should be continued.

The prognosis for testicular torsion is generally good if surgical intervention is performed early, before irreversible ischemic damage occurs. In scrotal torsion, if the testis is removed promptly, the animal typically recovers without long-term complications. However, if torsion is undiagnosed or untreated for more than 24 hours, the testis will become necrotic, and the risk of peritonitis and systemic infection increases, leading to a guarded prognosis. In cryptorchid torsion, the prognosis is more guarded due to the delay in diagnosis and the potential for peritonitis. The overall survival rate is high with appropriate surgical treatment, but the affected testis is usually non-viable and must be removed. Fertility may be preserved if the contralateral testis is normal, but if both testes are affected or if the torsion is bilateral, infertility may result. Recurrence is unlikely after orchiectomy. Negative prognostic indicators include delayed presentation, severe systemic signs, and the presence of neoplasia.

Postoperative follow-up is essential to monitor for complications such as infection, seroma formation, or recurrence of torsion in the contralateral testis. The animal should be re-examined 7-10 days after surgery to assess wound healing and remove sutures. If the animal is intended for breeding, semen evaluation should be performed 60-90 days after surgery to assess sperm quality and count. Serial ultrasonography of the remaining testis may be recommended to monitor for any abnormalities. In cases of cryptorchid torsion, the animal should be monitored for signs of peritonitis or abscess formation. Long-term follow-up is recommended for animals with testicular neoplasia, as some tumors (e.g., Sertoli cell tumors) can metastasize. Regular physical examinations and imaging may be advised.

Pearls: 1) Always consider testicular torsion in any intact male dog with acute scrotal pain or abdominal pain, especially if cryptorchid. 2) Doppler ultrasound is the most reliable diagnostic tool; absence of blood flow is pathognomonic. 3) In cryptorchid torsion, the testis may be located in the abdomen or inguinal canal; thorough abdominal exploration is necessary. 4) Early surgical intervention is crucial to prevent testicular necrosis and systemic complications. 5) In valuable breeding animals, detorsion and orchiopexy may be attempted if the testis is viable, but the risk of recurrence is high. Pitfalls: 1) Delaying surgery while awaiting diagnostic tests can lead to irreversible testicular damage. 2) Misdiagnosing cryptorchid torsion as acute pancreatitis or other abdominal emergencies can delay treatment. 3) Attempting to manually detort the testis without surgery is ineffective and may worsen the condition. 4) Failing to perform a thorough abdominal exploration in cryptorchid cases may miss the affected testis. 5) Overlooking the possibility of testicular neoplasia in chronic cases can lead to inadequate treatment.

Analgesics: Morphine (0.5-1 mg/kg IM or IV q4-6h) or buprenorphine (0.01-0.02 mg/kg IV q8-12h) for pain management. NSAIDs such as carprofen (2.2 mg/kg PO q12h) or meloxicam (0.2 mg/kg SC once, then 0.1 mg/kg PO q24h) may be used postoperatively, but caution with renal function. Antibiotics: Amoxicillin-clavulanate (20 mg/kg IV or PO q8h) or cefazolin (22 mg/kg IV q8h) for perioperative prophylaxis. In cases of peritonitis, metronidazole (10 mg/kg IV q12h) may be added. Fluids: Lactated Ringer's solution or Normosol-R at 10-20 ml/kg/h IV during surgery, then adjusted based on hydration status. Antiemetics: Maropitant (1 mg/kg SC q24h) for vomiting. Gastroprotectants: Omeprazole (1 mg/kg IV q24h) or famotidine (0.5 mg/kg IV q12h) to prevent stress ulcers. Hormonal therapy is not indicated for torsion. In cases of testicular neoplasia, additional chemotherapy may be required, but this is beyond the scope of emergency treatment.

Testicular torsion is a well-documented but relatively rare condition in veterinary medicine. Most literature consists of case reports and retrospective studies. A retrospective study by Johnston et al. (2001) in the Textbook of Canine and Feline Theriogenology reported that torsion occurs most commonly in cryptorchid testes, with a higher incidence in large breeds. Another study by England and von Heimendahl (2010) in the BSAVA Manual of Small Animal Reproduction highlighted the importance of Doppler ultrasound in diagnosis. A case series by Smith et al. (2015) described 12 cases of scrotal torsion in dogs, all treated with orchiectomy, with excellent outcomes. There are no prospective randomized trials due to the rarity of the condition. Expert consensus from the American College of Theriogenologists (ACT) and the European College of Animal Reproduction (ECAR) recommends immediate surgical exploration in suspected cases. The use of detorsion and orchiopexy is controversial, with most experts recommending orchiectomy due to the high risk of recurrence and ischemic damage. Overall, the evidence supports early surgical intervention as the standard of care.