Severe Orchitis in Dogs — Treatment Protocol

Overview

Etiology (Identify Before Treating)

Diagnostic Workup (Concurrent with Treatment Initiation)

• CBC + serum chemistry — assess systemic infection, leukocytosis, organ function
• Brucella canis serology — RSAT, AGID, or PCR; mandatory before any treatment
• Scrotal/testicular ultrasound — abscess formation, testicular torsion, neoplasia
• Urinalysis + urine culture — ascending infection source
• Semen culture / epididymal aspirate culture — if Brucella negative, guide antibiotic selection
• Blood culture — if systemic sepsis suspected

Treatment Protocol

1. Brucella canis — If Positive

Castration (orchiectomy) is the treatment of choice. Medical management alone does not eliminate B. canis and dogs remain infectious reservoirs.

• Castration: bilateral orchiectomy + closed scrotal ablation
• Post-castration antibiotics (reduce shedding, not curative as sole treatment):
  • Doxycycline 10 mg/kg PO q12h × 4 weeks + enrofloxacin 5 mg/kg PO q24h × 4 weeks
  • OR minocycline 12.5 mg/kg PO q12h × 4 weeks
• Notify owner of zoonotic risk; advise testing of in-contact humans
• Retest serology 3 and 6 months post-treatment

2. Non-Brucella Bacterial Orchitis — Breeding Dog (Fertility Preservation Attempted)

• Enrofloxacin 5–10 mg/kg PO/IV q24h (excellent tissue penetration, broad gram-negative coverage)
• OR trimethoprim-sulfonamide 15 mg/kg PO q12h (good scrotal tissue penetration)
• Duration: minimum 4–6 weeks; adjust when culture results available

• Carprofen 2.2 mg/kg PO q12h or meloxicam 0.1 mg/kg PO q24h
• Reduces pain, edema, and thermal damage to spermatogenesis
• Do not use corticosteroids — immunosuppression worsens bacterial infection

• Hydrotherapy: cool water compresses or cool hydrotherapy to the scrotum 3–4×/day for 10–15 min (reduces thermal injury to germinal epithelium)
• Prevent self-trauma: E-collar; scrotal support bandage if needed
• Restrict exercise; cage rest during acute phase

• Reassess at 48–72 hours; if no improvement, repeat ultrasound to rule out abscessation
• Semen evaluation 2–3 months post-recovery (spermatogenesis cycle ~62 days)

3. Non-Brucella Bacterial Orchitis — Non-Breeding Dog or Failed Medical Management

• Eliminates infection source
• Prevents contralateral spread via lymphatics
• Consider if: abscess formation, scrotal necrosis, systemic sepsis, or no response to 5–7 days of medical therapy
• Closed castration technique; scrotal ablation if severe dermatitis or necrosis present

• Continue systemic antibiotics 2–4 weeks post-castration based on culture/sensitivity

4. Abscess Management

• Ultrasound-guided drainage is not recommended as primary treatment (high recurrence, risk of peritonitis/fistula)
• Orchiectomy + aggressive debridement is preferred
• Intra-operative culture of abscess material
• Leave wound open for second-intention healing if contamination is extensive; daily wound lavage

5. Systemic Sepsis

• IV fluid resuscitation (lactated Ringer's or Plasmalyte, 20–30 mL/kg bolus, titrate)
• IV antibiotics: ampicillin-sulbactam 22 mg/kg IV q8h + enrofloxacin 5 mg/kg IV q24h (diluted, slow infusion)
• ICU monitoring; pain management with opioids (buprenorphine 0.02 mg/kg IV/IM q6–8h)
• Proceed to surgical castration once patient is stabilized

Prognosis

Key Points

• Always rule out Brucella canis first — it overrides the entire treatment plan and has zoonotic implications.
• Fluoroquinolones (enrofloxacin) and trimethoprim-sulfonamides are the preferred antibiotics due to their penetration into testicular tissue.
• Cool hydrotherapy is an often-overlooked but critical adjunct to preserve remaining spermatogenesis.
• If medical management has not produced clear improvement within 5–7 days, proceed to castration rather than continuing to delay.