April 15, 2017

Prostate-Specific Protein Can Be Used to Diagnose BPH in Middle-Aged Dogs

Measuring canine prostate-specific arginine esterase levels can be an alternative or complementary method to accurately diagnose benign prostatic hyperplasia in middle-aged dogs.
By JoAnna Pendergrass, DVM
Measuring canine prostate-specific arginine esterase (CPSE) levels can be an alternative or complementary method to accurately diagnose benign prostatic hyperplasia (BPH) in middle-aged dogs, according to a study recently published in BMC Veterinary Research.

The authors wrote that systematic CPSE quantification “can increase the likelihood of early [diagnosis of BPH] in apparently healthy middle-aged dogs.”
Prostatic diseases frequently affect middle-aged and older intact dogs. BPH develops spontaneously, with its development primarily influenced by testosterone. Because BPH can negatively affect fertility, an early diagnosis is preferable. However, clinical signs of BPH can be transient, making an early diagnosis potentially challenging.
Ultrasound-confirmed prostatomegaly often provides a conclusive BPH diagnosis. However, BPH can resemble other prostatic diseases (e.g., squamous metaplasia, prostatitis) on ultrasound, highlighting the need for additional diagnostic tools, such as CPSE measurement, to accurately diagnose the disease.
CPSE is an androgen-dependent protein that is similar to the human prostate-specific antigen. A previous study reported higher serum CPSE levels in dogs with BPH than in normal dogs.
For the current study, the authors evaluated 60 intact adult male dogs, each of which underwent a comprehensive examination:
  • Physical and digital rectal exam
  • Cytologic evaluation
  • Serum CPSE measurement
  • Transabdominal ultrasound
Ultrasound findings were classified as suggestive of BPH, cystic prostatic hyperplasia, or prostatitis. Cytologic samples were classified as BPH, squamous metaplasia, or prostatitis. Dogs were grouped according to cytologic presence or absence of BPH:
  • Study group: n = 29, BPH positive
  • Control group: n = 31, BPH negative
ELISA was performed to measure serum CPSE levels, using the manufacturer-provided cut-off value of 61 ng/mL for BPH.
The authors calculated a correlation coefficient to determine how well CPSE results agreed with other diagnostic results regarding BPH positivity or negativity. Using cytology as the reference method, CPSE sensitivity and specificity were also calculated.
Clinical Examination, Ultrasound, and Cytologic Findings
Median weight was markedly higher in the study group (66 lb) than the control group (42 lb). In addition, study group dogs were older (median age, 9 years) than control group dogs (median age, 5 years). Notably, 7 of 29 study group dogs showed no clinical signs of BPH.
In the study group, 8 of 29 dogs had prostatitis; the authors noted that multiple diseases can concomitantly exist in the canine prostate. In the control group, prostatitis was present in 6 dogs and squamous metaplasia was present in 2 dogs.
CPSE Levels
Median CPSE levels were significantly higher in the study group (160.1 ng/mL) than in the control group (29.1 ng/mL). CPSE levels were significantly correlated with age and prostatic volume, but not weight. The nonsignificant correlation between CPSE and weight was notable, indicating that CPSE levels can be used to diagnose BPH in large breeds, or even in obese dogs for which digital rectal examination is not possible.
Testing Agreement
CPSE results showed high levels of agreement with the other diagnostic tests, with the highest level of agreement being with cytology.
In the study group, 1 of 29 dogs had a CPSE level below 61 ng/mL (false negative). In the control group, 3 of 31 dogs had a CPSE level markedly above 61 ng/mL (false positive); these 3 dogs had either prostatitis or squamous metaplasia. The authors determined a 97% sensitivity and 90% specificity for CPSE.
Taken together, these study results demonstrate the diagnostic accuracy of CPSE levels for detecting BPH in middle-aged dogs. In addition to diagnostic accuracy, the authors proposed using CPSE levels to assess success of BPH medical treatment.
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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