Ultrasonographic Features of the Prostate Gland in Dogs in Jaipur, Rajasthan

The canine prostate gland, an integral component of the male reproductive system.In dogs, the prostate gland serves as the sole male accessory gland, playing a crucial role in the secretion of components of seminal plasma (Smith, 2008).
       
The prostate gland in adult dogs is bilobed (Russo et al., 2012) and oval-shaped, exocrine gland, positioned dorsally adjacent to the rectum, ventrally to the pubic symphysis, laterally to the abdominal wall and cranially to the bladder. It serves as a pathway for the urethra and the vas deferens, facilitating the transport of sperm to the urethra (Leis-Filho et al., 2018).
       
The size of the canine prostate gland can vary due to factors such as the natural aging process, breed, body weight, sexual maturity and disease (Dennis et al., 2010; Gadelha et al., 2009).
       
Various clinical procedures including history, physical and laboratory exams, rectal palpation, radiography, ultrasonography, computed tomography, magnetic resonance imaging and other diagnostic techniques are the main methods for diagnosing prostatic disorders. Radiography, ultrasonography, computed tomography, magnetic resonance imaging and history, physical and laboratory exams are the main methods for diagnosing prostatic disorders.
       
The normal prostate gland is typically not well-defined on radiographic imaging. However, when enlarged, it alters the anatomical position of the rectum and urinary bladder, making it more distinguishable. While radiography cannot differentiate parenchymal abnormalities of the prostate, ultrasonography can identify those abnormalities (Singh et al., 2021).
       
Leroy et al., (2013) observed that transabdominal ultrasonography has become the preferred imaging method for evaluating the prostate gland in dogs.
       
B-mode ultrasound is frequently employed to examine the shape, size, position, margin and internal architecture of parenchymatous organs. This technique has been adapted for the examination of prostate gland in order to diagnose and differentiate diseases, as well as to monitor response to treatment (Kawakami et al., 1993).
       
Diagnostic ultrasonography has been widely used for examining the female reproductive tract but less frequently in males. However, ultrasonography (US) can offer valuable insights into the evaluation of male reproductive health (Ali et al., 2022).
       
In conclusion, ultrasonography is an effective and reliable technique for evaluating the nature and severity of disease, which aids in assessing the prognosis and outcome of the condition (Kumar et al., 2012).
       
The primary objective of the present observational study was to provide a comprehensive reference for the dimensions of the prostate gland in male dogs, devoid of any current or prior lower urogenital system diseases. A secondary aim of the study was to evaluate the impact of age and body weight on prostatic size in dogs.

The research work was conducted at the Department of Veterinary Medicine in collaboration with Department of Veterinary Clinical Complex (VCC), Post Graduate Institute Veterinary Education and Research (PGIVER), Jaipur, Rajasthan, from October 2021 to March 2022. Selected dogs were divided into three age groups: 2-3 years, 3-4 years and 4-5 years. A minimum of 10 dogs were assigned to each age group and designated as groups I, II and III, respectively. Ultrasonographic examination was performed using a convex transducer with a frequency ranging between 1 MHz to 8 MHz. The ultrasonography machine utilized for this purpose was the MY LAB SEVEN (make-ESOTE).
       
Transabdominal ultrasonography was conducted on all 60 dogs using a 1-8 MHz probe operating at a frequency of 6 MHz. The transducer was positioned on the caudoventral abdomen, on one side of the penis or prepuce, cranial to the scrotum. The urinary bladder was initially identified on the scan. Once located, the prostate gland was scanned in both longitudinal and transverse planes.

The prostate gland can be effectively imaged via a trans-abdominal modality, utilizing the prepubic or parapubic areas, in both German shepherd and Labrador breeds across various age groups. The gland is situated adjacent to the trigone of the distended urinary bladder. Both sagittal and transverse planes of the prostate gland can be visualized effectively using transabdominal ultrasonography (Image 1, 2), as imagined by Atalan et al., (1999), Cooney et al., (1992) and Gadelha et al., (2009).




       
Prostatic urethra was centrally positioned within the gland, exhibiting a hypo- or anechoic area bordered by a thin hyperechogenic layer, consistent with the findings described by Freitas et al., (2015).
       
The prostate gland exhibited a characteristic appearance characterized by a hypoechoic homogeneous parenchyma with moderately echogenic stippling distributed uniformly throughout. The capsule appeared relatively echogenic (Image 1, 2) and was easily identifiable. Similar prostatic appearances were also reported by Feeney et al., (1987), Juniewicz et al., (1989), Divya et al. (2010) and Khanbazi et al., (2021), who noted that prostates were clearly differentiated sonographically.
 
A. The ultrasonographic features of prostate gland
 
The ultrasonographic features of prostate gland in German Shepherd- (Table 1)
 
The ultrasonographic features of prostate gland in Labrador- (Table 2)
 
In a similar study involving 36 male dogs, Gadelha et al., (2009) also observed a positive correlation between body weight and animal age. Furthermore, Ruel et al., (1998) reported a significant positive correlation (p<0.001) between each prostatic parameter and both body weight and age in a study including 100 healthy intact male dogs aged between 9 months and 14 years.
       
Moresco and Goncalves (2019) studied 21 mixed breed dogs. They found mean ultrasonographic measurements for length and width in each group as follows: G I (0-3 years, n=11): 2.04±0.30 cm and 2.40± 0.46 cm, G II (3-7 years, n=7): 2.28±0.27 cm and 2.82± 0.43 cm and G III (7 years and above, n=4): 3.02±0.80 cm and 3.33±0.97 cm, respectively.
       
Ghadiri et al., (2013) examined 10 intact male dogs aged 2 to 4 years, weighing between 16 and 23 kg and reported ultrasonographic measurements of prostate gland length and width as 3.35±0.4 cm and 3.42±0.53 cm, respectively. The slight differences observed between the present and previous studies may be attributed to variations in sample size and age groups of the dogs examined.
       
In a study by Ruel et al., (1998) involving 100 sexually mature male intact dogs with a mean age of 5.1±3.4 years and body weight of 18±11.8 kg, transabdominal ultrasono-graphy showed mean length 3.4±1.1 cm and width  3.3±0.9 cm of prostate gland. The observed higher measurements in Ruel et al., (1998) study compared to the GSD and Labrador groups (21.49±0.78 kg and 20.31±0.89 kg) can be attributed to differences in both breed characteristics and sample size.
 
Analysis of ultrasonographic features with age and body weight of dogs
 
In all three age groups and body weight categories of German Shepherd (GSD) and Labrador retriever dogs, both prostatic parameters, length and width, exhibited a positive correlation with age and body weight (Table 1, 2). These findings are consistent with the observations made by Kadambari et al., (2015).




       
Ultrasonography of prostate gland in Labrador and German shephered dogs in this area is done first time. Study reveals a positive correlation between prostate gland size with age and body weight.

The prostate gland has hypoechoic homogenous parenchyma and hyperechoic capsule with moderately echogenic stippling present in a uniform pattern throughout the gland in ultrasonography. Prostate appeared bi lobbed in longitudinal plane and appeared single lobed in transverse plane. Ultrasonography proved to be a very effective diagnostic imagining tool to know about prostate gland parameters which help in clinical evaluation of prostatic diseases and in evaluation of response to therapy.

Authors are thankful for the Dean, PGIVER, Jaipur for providing the facilities for this work, also thankful to dog owners for their kind cooperation during the ultrasonography examination.

The authors declare no conflict of interest.