• View in gallery View in gallery View in gallery

    Ventrodorsal (A), right lateral (B), and left lateral (C) abdominal radiographic images of a 12-year-old 6.6-kg sexually intact male Longhaired Dachshund referred because of a history of hematuria and suspected urinary bladder herniation.

  • View in gallery View in gallery View in gallery

    Same images as in Figure 1. The prostate is enlarged (black asterisks), resulting in dorsal deviation of the descending colon and rectum (black arrows) and cranial displacement of the urinary bladder (white asterisks). A single smoothly marginated, ovoid, soft tissue opaque mass is in the right inguinal region (white dashed circle).

  • View in gallery View in gallery

    Ultrasonographic images of the prostate (A) and right inguinal region (B) of the dog described in Figure 1. A—The prostate is hyperechoic and enlarged (dashed white circle), measuring 4.4 X 2 X 4.4 cm, with a heterogeneous echotexture and irregular margins. Small, anechoic, thin-walled cysts (black arrows) are in the prostate. B—Within the swelling of the right inguinal region, there is an irregularly shaped, thin-walled, distally enhancing, fluid-filled, anechoic cystic structure (white asterisk) measuring 3.0 X 1.0 cm.

  • 1.

    Waters DJ, Roy RG, Stone EA. Retrospective study of inguinal hernia in 35 dogs. Vet Surg. 1993;22(1):4449.

  • 2.

    Thrall DE, Robertson ID. The abdomen. In: Thrall DE, Robertson ID, eds. Atlas of Normal Radiographic Anatomy & Anatomical Variants in the Dog and Cat. 2nd ed. Elsevier, Inc.; 2016:241295.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 3.

    Atalan G, Holt PE, Barr FJ. Ultrasonographic estimation of prostate size in normal dogs and relationship to bodyweight and age. J Small Anim Pract. 1999;40(3):119122.

    • Search Google Scholar
    • Export Citation
  • 4.

    Smith J. Canine prostatic disease: a review of anatomy, pathology, diagnosis, and treatment. Theriogenology. 2008;70(3):375383.

  • 5.

    Renfrew H, Barrett EL, Bradley KJ, Barr FJ. Radiographic and ultrasonographic features of canine paraprostatic cysts. Vet Radiol Ultrasound. 2008;49(5):444448.

    • Search Google Scholar
    • Export Citation
  • 6.

    Vititoe KP, Grosso FV, Thomovsky S, Lim CK, Heng HG. Inguinal herniation of a mineralized periprostatic cyst in a dog. Can Vet J. 2017;58(12):13091312.

    • Search Google Scholar
    • Export Citation

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  • 1 Department of Clinical Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, MS

Abstract

In collaboration with the American College of Veterinary Radiology

Abstract

In collaboration with the American College of Veterinary Radiology

History

A 12-year-old 6.6-kg sexually intact male Longhaired Dachshund was presented for evaluation because of a history of hematuria. The owners reported that, aside from hematuria, the patient had been otherwise healthy. The patient was first seen by the referring veterinarian. Radiographic examination at that visit was reported to have been normal. A focal ultrasonographic examination was performed on reevaluation 3 days later, and the referring veterinarian reported a 1.0 X 1.5-cm anechoic, fluid-filled structure within the inguinal canal. The urinary bladder was visualized within the abdomen and contained hyperechoic sediment. The prostate was enlarged with numerous round, variably sized, anechoic cystic structures. The referring veterinarian expressed concern for urinary bladder herniation, and the patient was referred to the authors’ institution for further evaluation.

On referral examination, the patient was bright, alert, and responsive. A few drops of red-tinged urine dribbled from the penis during the initial triage workup. A smoothly marginated, freely movable, soft, subcutaneous mass approximately the size of a golf ball was palpated to the right of the prepuce. Rectal examination revealed an enlarged and irregularly marginated prostate. The remaining findings on physical examination were within reference limits. Results of a CBC and serum biochemical analyses were unremarkable. A urinalysis revealed 4+ proteinuria (reference range, 0 to 4+), hematuria (25 to 50 RBCs/hpf; reference range, 0 to 5 RBCs/hpf), and a large amount of bilirubin (reference range, negative to large). A sample of urine was submitted for bacterial culture, which yielded no signs of growth after 48 hours. Abdominal radiography was performed (Figure 1).

Figure 1
Figure 1
Figure 1
Figure 1

Ventrodorsal (A), right lateral (B), and left lateral (C) abdominal radiographic images of a 12-year-old 6.6-kg sexually intact male Longhaired Dachshund referred because of a history of hematuria and suspected urinary bladder herniation.

Citation: Journal of the American Veterinary Medical Association 259, S1; 10.2460/javma.20.12.0705

Formulate differential diagnoses, then continue reading.

Radiographic Findings and Interpretation

On radiographic examination, the prostate was enlarged and caused dorsal deviation of the descending colon and rectum, as well as cranial displacement of the urinary bladder (Figure 2). A single smoothly marginated, ovoid, soft tissue opaque structure was in the subcutaneous tissues of the right inguinal region and caused mild ventral deviation of the prepuce and os penis.

Figure 2
Figure 2
Figure 2
Figure 2

Same images as in Figure 1. The prostate is enlarged (black asterisks), resulting in dorsal deviation of the descending colon and rectum (black arrows) and cranial displacement of the urinary bladder (white asterisks). A single smoothly marginated, ovoid, soft tissue opaque mass is in the right inguinal region (white dashed circle).

Citation: Journal of the American Veterinary Medical Association 259, S1; 10.2460/javma.20.12.0705

To better characterize the changes to the prostate and the mass in the inguinal region, abdominal ultrasonography was performed (Figure 3). Ultrasonographic findings included an enlarged, irregularly shaped, and irregularly marginated prostate which measured 4.4 X 2 X 4.4 cm. Numerous round, sharply marginated, distally enhancing anechoic cysts were seen throughout the prostatic parenchyma. An irregularly shaped, thin-walled, distally enhancing anechoic structure measuring 3.0 X 1.0 cm was seen extending from the cranial aspect of the prostate into the right inguinal region. The urinary bladder was identified in its normal anatomic location and contained numerous hyperechoic foci consistent with proteinaceous, cellular, or hemorrhagic debris, as well as a larger (1.81 X 0.32 X 0.48 cm), irregularly shaped, sharply marginated, heterogeneously hyperechoic structure that was likely a blood clot. Based on imaging findings, the primary differential diagnosis was a periprostatic cyst that had herniated into the right inguinal region.

Figure 3
Figure 3
Figure 3

Ultrasonographic images of the prostate (A) and right inguinal region (B) of the dog described in Figure 1. A—The prostate is hyperechoic and enlarged (dashed white circle), measuring 4.4 X 2 X 4.4 cm, with a heterogeneous echotexture and irregular margins. Small, anechoic, thin-walled cysts (black arrows) are in the prostate. B—Within the swelling of the right inguinal region, there is an irregularly shaped, thin-walled, distally enhancing, fluid-filled, anechoic cystic structure (white asterisk) measuring 3.0 X 1.0 cm.

Citation: Journal of the American Veterinary Medical Association 259, S1; 10.2460/javma.20.12.0705

Treatment and Outcome

Fine-needle aspirates of the prostate were performed, as well as an ultrasound-guided centesis of the periprostatic cyst. The prostatic aspirate samples were consistent with benign prostatic hyperplasia. Fluid cytology from the periprostatic cyst showed minimal mixed inflammatory and low numbers of suspected reactive mesothelial cells, with no infectious agents identified. Follow-up bacterial culture performed on a sample of the cystic fluid did not yield any growth after 48 hours. The patient was discharged with instructions to follow-up with the referring veterinarian for surgical management of the periprostatic cyst that had herniated into the right inguinal region and castration to treat the benign prostatic hyperplasia and periprostatic cyst.

Comments

Benign prostatic hyperplasia (BPH) is the most common prostatic disorder in sexually intact male dogs,1 especially those older than 7 years of age. The gold standard for definitive diagnosis is usually through biopsy, but a presumptive diagnosis is often made through a combination of history, physical examination, imaging, and prostatic fine-needle aspiration. The prostate should not be visible on radiographs under normal circumstances, but an enlarged prostate protrudes visibly from the cranial aspect of the iliopubic eminence in sexually intact males.2 Similarly, it has been reported that the prostatic size on ultrasonography will vary with age, breed, body weight, and neuter status.3

Although the exact etiology of periprostatic cysts remains unclear, they may be remnants of the uterus masculinus or the result of ductal occlusion from squamous metaplasia or a chronic prostatic hematoma.4,5 Periprostatic cysts attach externally to the prostate through adhesion or a piece of tissue,4,5 and as such, they do not communicate with the urethra. This differs from a retention prostatic cyst, which is reported to be more associated with the prostatic walls and often does communicate with the urethra.4,5 Although rare, this disease is usually seen in older, sexually intact male, large-breed dogs accompanied by concurrent BPH.6 As with other cysts, they are usually benign until fluid accumulates and the structure grows to the point where it can interfere with the surrounding structures. Usually, these cystic structures compress on the urinary bladder or colon, leading to dysuria and tenesmus, respectively.

Imaging is useful in cases such as this to fully assess the palpable swelling, to determine whether the swelling is a mass or a hernia, and to determine which organs are contained within the hernia. One concern when addressing a case such as this is the location of the urinary bladder. Positive-contrast cystography can be used to localize the urinary bladder; however, cystography provides no information about the prostate or the presence or location of a periprostatic cyst. Curiously, mineralization of periprostatic cysts may be more common than previously reported, and if present, can help differentiate the structure from the urinary bladder on survey radiographs.5 Because mineralization of these cysts is often thin, it may be more easily seen on survey radiography than on ultrasonography5; however, mineralization was not seen in this case. Ultrasonography was elected in this case to further investigate the clinical swelling due to the lower cost of ultrasonography, compared with CT, and the ease of ultrasound-guided aspiration of the prostate and cyst. Ultrasonographic examination additionally confirmed an appropriate abdominal location of the urinary bladder and confirmed that the anechoic structure within the inguinal hernia was confluent with the prostate, resulting in the diagnosis of inguinal herniation of a periprostatic cyst. Another consideration would have been abdominal and pelvic CT. Although CT would have provided greater detail of the abdominal structures, this imaging modality is more costly and would not have allowed for immediate aspiration of the cyst as easily as did ultrasonography.

In this patient, we suspected BPH contributed to the hematuria. It was unclear whether the underlying origin for the inguinal hernia was congenital or traumatic; however, the mass effect of the periprostatic cyst combined with the effects of the hormone relaxin might have played a role in weakening of the pelvic musculature.5,6 Although both are rare, perineal herniation of periprostatic cysts is more commonly reported than inguinal herniation.5,6 Herniation of the periprostatic cyst was likely secondary to the BPH that grew slowly until the cyst passed through the hernia. In cases such as this, surgical correction of the hernia is warranted. Neutering of the patient will also help address BPH and hopefully in turn the periprostatic cyst.

Acknowledgments

The authors declare no financial or other conflicts of interest.

References

  • 1.

    Waters DJ, Roy RG, Stone EA. Retrospective study of inguinal hernia in 35 dogs. Vet Surg. 1993;22(1):4449.

  • 2.

    Thrall DE, Robertson ID. The abdomen. In: Thrall DE, Robertson ID, eds. Atlas of Normal Radiographic Anatomy & Anatomical Variants in the Dog and Cat. 2nd ed. Elsevier, Inc.; 2016:241295.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 3.

    Atalan G, Holt PE, Barr FJ. Ultrasonographic estimation of prostate size in normal dogs and relationship to bodyweight and age. J Small Anim Pract. 1999;40(3):119122.

    • Search Google Scholar
    • Export Citation
  • 4.

    Smith J. Canine prostatic disease: a review of anatomy, pathology, diagnosis, and treatment. Theriogenology. 2008;70(3):375383.

  • 5.

    Renfrew H, Barrett EL, Bradley KJ, Barr FJ. Radiographic and ultrasonographic features of canine paraprostatic cysts. Vet Radiol Ultrasound. 2008;49(5):444448.

    • Search Google Scholar
    • Export Citation
  • 6.

    Vititoe KP, Grosso FV, Thomovsky S, Lim CK, Heng HG. Inguinal herniation of a mineralized periprostatic cyst in a dog. Can Vet J. 2017;58(12):13091312.

    • Search Google Scholar
    • Export Citation

Contributor Notes

Corresponding author: Dr. Lee (aplumley@cvm.msstate.edu)