Urogenital System

• What are the functions of the urinary system of the dog?

  1. Regulate the chemical composition and volume of the body fluids through the process of osmoregulation.
  2. Remove the nitrogenous waste products and excess water from the body through excretion.
  3. Act as an endocrine gland by the secretion of the hormone erythropoietin.
• Erythropoietin

  • important in the red blood cell production and formation
• Kidney

  • paired reddish-brown organs
• Kidney


  located on the dorsal part of the abdominal cavity
• Kidney

  Right kidney is higher than the left
• Kidney


  Cranial part of the right kidney lies in a complementary fossa of the liver, which is known as the renal impression found on the caudate process of the right hepatic lobe
• Perirenal fat

  mass of protective fat surrounding the kidney and holding its place
• Fibrous capsule


  loosely attached (except at the hilus) covering of the kidneys
• Renal cortex

  outer layer of the kidney parenchyma beneath the capsule; characterized by their color and granular appearance
• Renal medulla

  inner layer of the kidney parenchyma; characterized by the striated appearance
• Renal crest

  ridge resulting from the complete fusion of the medulla and pyramids
• Renal calyx

  cup-shaped structure receiving urine from the renal papillae
• Renal sinus


  space occupied by the ureter, renal blood vessels and nerve entering the kidney
• Renal hilus


  opening to the renal sinus (renal vein, artery, and ureter passes through)
• Renal pelvis

  expanded proximal end of the ureter
• Pars of the kidney

  Functional units:

  • nephrons- urine production
  • renal tubules- convey the urine to the renal pelvis)
• Ureter


  muscular tube
• Ureter


  can be divided into an abdominal part or pelvic part
• Ureter

  passes caudally in the retroperitoneal space along the dorsal body wall
• Ureter

  turns medially to enter the broad uterine ligament in the female and the mesoductus deferens in the male
• Ureter

  ends by inserting into the dorsolateral surface of the urinary bladder
• Ureter

  The length of the intramural course prevents reflux of urine into the ureter when the pressure is raised within the bladder, but it does not hinder further filling of the bladder since the resistance is normally overcome by peristaltic contractions of the ureteric wall
• Urinary bladder

  hollow musculomembranous organ
• Urinary bladder


  functions in collecting and storing urine
• Urinary bladder

  varies in form, size, and position depending on the amount of urine it contains when it contracted
• Urinary bladder 


  small, and globular organ and lies on the pubic bone
• Urinary bladder

  extends in the abdomen, especially in carnivores, but for large animals, it is more confined in the pelvic cavity
• Urinary bladder

  during filling, it enlarges gradually and becomes a pear-shaped
• Parts of the urinary bladder

  • Body
  • Neck
  • Fundus
  • Detrusor muscle
  • Ureter ostium
  • Trigone
• Parts of the kidney

  • Fibrous capsule
  • Renal cortex
  • Renal medulla
  • Renal crest
  • Renal calyx
  • Renal sinus
  • Renal hilus
  • Renal pelvis
• Urinary bladder

  consists of:

  • inner layer- made up of transitional epithelium; enables the walls to expand when filling with urine
  • submucosal layer- elastic tissue and smooth muscle; arranged in folds to allow expansion
  • peritoneum- bladder is surrounded by a layer of peritoneum which covers only the cranial end lying in the abdomen
• Urinary bladder

  The bladder is kept in a position of three peritoneal folds:

  • Middle umbilical (median or ventral ligament)
  • Two lateral umbilical folds- contain in their free border the round ligament
• Urethra

  • tube that conveys urine caudally from the bladder through the pelvic cavity to the outside
• Urethra

  Female- serves in conveying urine

  • urethra is a short tube, opening into the floor of the reproductive tract at the junction of the vagina and vestibule

  Opening: external urethral orifiice

  • located on the center of a small ridge, which is the urethral tubercle
  • useful landmark when catheterizing a bitch and can be seen using a speculum

  Located: urethral tubercle
• Urethra

  Male- carries urine, semen, and seminal excretions

  Divided into two parts:

  • pelvic urethra
  • penile urethra