June 25, 2017

Computed Tomography and Canine Prostate Disease

Computed tomography has potential for evaluating the canine prostate, potentially adding to the tools that can assist practitioners with the diagnosis of prostate disease.
By JoAnna Pendergrass, DVM
Computed tomography (CT) has potential diagnostic value for evaluating the canine prostate, according to a retrospective study recently published in BMC Veterinary Research. “By measuring the density, homogeneity, the tissue surrounding prostatic cysts, and the prostatic size,” the researchers wrote, “it is possible to draw conclusions concerning the health of the prostate.”
 
Canine prostatic disease commonly occurs in older, intact male dogs and is a frequent reason for veterinary visits. The traditional diagnostic tools available for canine prostatic disease—digital rectal exam (DRE), radiography, and ultrasound—have drawbacks. For example, DRE and radiography results may be insufficient. Also, prostate visualization is limited with transabdominal ultrasound.
 
CT presents a viable alternative for detailed canine prostate examination. To date, however, few studies have evaluated CT’s diagnostic usefulness for canine prostatic disease. The aim of the current study was 2-fold:
  • Examine age-related canine prostatic morphology
  • Determine the diagnostic value of measuring canine prostate density
 
Study Design
The researchers analyzed the CT records of 50 intact, male pet dogs. Dogs were grouped by age (<4 years, 4–8 years, >8 years) and prostate morphology (homogeneous prostate, inhomogeneous prostate, cysts).
 
Each dog underwent pre- and postcontrast CT scans of the prostate. Images were evaluated for prostate size and density. Density was measured using Hounsfield Units (HU), which are standardized units of measure.
 
Of the 50 dogs, 47 also received a transabdominal ultrasound for prostate examination. These images were evaluated for prostate size, echogenicity, and tissue texture and compared with CT results.
 
Results
­Age-related Prostate Morphology
Dogs younger than 4 years of age had predominantly homogeneous prostates. In the older dogs, prostatic cysts were the most common morphologic type; notably, nearly 70% of dogs older than age 8 years had prostatic cysts. Such results align with a previous study that described age-related canine prostatic development, namely hyperplastic growth between 6 and 10 years of age.
 
Prostate Density
Density was analyzed in the pre- and postcontrast scans according to morphologic group. Across groups, HU values were significantly higher in the postcontrast than in the precontrast scans.
 
Postcontrast HU values were highest for inhomogeneous prostates, which were most common in the study’s oldest dogs. Age-related prostatic hyperplasticity and histologic changes (increased glandular tissue, decreased stromal tissue) could have caused diffuse and inhomogeneous contrast agent uptake.
 
Postcontrast HU values were lowest for homogeneous prostates, indicating low tissue density. The researchers noted that a normal, healthy prostate is generally homogeneous with hypodense tissue structure. Interestingly, for cystic prostates, postcontrast HU values were higher for the tissue surrounding the cysts than for the cysts themselves, suggesting greater vascularization in the surrounding tissue. 

Researchers concluded that “the different HUs reflected age-related changes and alterations in the prostate.”
 
Prostate Size
Prostate size varied between morphologic groups. Overall, homogeneous prostates were smallest and cystic prostates were largest. The increased size of cystic and inhomogeneous prostates likely indicated benign prostatic hyperplasia (BPH) and natural aging. However, the researchers noted, suspected cases of BPH were not confirmed in this study.
 
Ultrasound
Generally, ultrasound and CT results were similar. In some cases, ultrasound and postcontrast CT results differed, reflecting the ability of contrast CT to detect more clearly changes in tissue structure and vascularization.
 
Discussion
The researchers concluded that measuring prostatic density using CT has diagnostic usefulness for canine prostatic disease. They proposed further CT examination of the canine prostate, taking into consideration other factors of canine aging, such as breed and weight.
 
 
Dr. JoAnna Pendergrass received her Doctor of Veterinary Medicine degree from the Virginia-Maryland College of Veterinary Medicine. Following veterinary school, she completed a postdoctoral fellowship at Emory University’s Yerkes National Primate Research Center. Dr. Pendergrass is the founder and owner of JPen Communications, a medical communications company.

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