SFB Block 4

Kidney

Bean shaped organ located in dorsally in the abdominal cavity in the lumbar region
surrounded by fat
enables mammals to survive under conditions in which there is highly variable access to water and salts
functions: urine production, plasma filtration, metabolic waste and xenobiotics excretion, retrieves metabolic substances (water, glucose, electrolytes, low MW proteins), responds to water, electrolyte and acid-base disturbances, gluconeogenesis, endocrine functions (calcitriol, renin, and erthyropoietin)

Renin

a hormone activator, renal regulation of blood pressure, essential part of the renin-angiotensin-aldosterone system (RAA system)

Calcitriol

stimulated by PTH in response to hypocalcemia

Erythropoietin

hormone (glycoprotein, growth factor), essential for erythropoiesis

Cortex

outer layer of kidney where nephrons (blood filtering units) begin

Hilus

medially oriented
an indented area on the surface of an internal organ where vessels and functional ducts enter/exit that organ

Medulla

inner section that regulates urine concentration
contains renal pyramids and renal crest

Renal crest

where all the tips of the renal pyramids fuse

Renal Pyramids

each tip has an orifice

Renal pelvis

dilation of the ureter
where all the urine collects

Renal Sinus

contains fat at the level of the hilus
holds renal pelvis

Ureters

drain urine
emerge from the hilus of the kidney
run caudally to the dorsal aspect of the urinary bladder
oblique passage through its wall that is compressed when pressure arrives

Urinary bladder

deposits urine between micturitions
position varies based on its plentitude (flow of abdomen or floor of pelvic inlet)
no visible sphincter, but urethral muscle keeps urethra constricted

divided into apex, body, and neck (pointed towards urethra)

Urethral muscle

muscular structure that regulates the outflow of urine from the bladder into the urethra

Uretal orifice

orfice between bladder and urethra

Trigone

a triangular muscular structure located between the bladder and urethra. Effective connection between the ureters and the trigone are vital for proper functioning of the ureteral valve mechanism

Female Urethra

short, pelvic only
runs caudally in the pelvic cavity to open at junction of vagina and vestibule

Male urethra

long, 2 segments
pelvic - receives ducti deferentes
penile - inside the penis

Ovaries

female gonads (gametogenesis)
close to tips of uterine horns
attached to abdominal wall and uterus via ligaments, enclosed in an ovarian bursa
endocrine function (estrogen, progesterone, testosterone)

Ovary cortex

outer layer of ovary

follicles located within

Ovary medulla

a highly vascular stroma in the center of the ovary. It forms from embryonic mesenchyme and contains blood vessels, lymphatic vessels, and nerves

Uterine tubes

Salpinx, fallopian tube, oviduct
Catches the oocyte, after ovulation; site of fertilization; delivers fertilized ova in the uterine horn

Infundibulum

funnel shaped part of the uterine tube; covers the ovary to capture the oocyte, after the rupture of a mature follicle

Uterus

site of gestation, ensures physiological exchanges between fetus and the mother

endometrium (mucosa, Myometrium (muscle), perimetrium

Y shaped: uterine horns and uterine body

surrounded by broad ligament

cervix at the end

Cervix

controls access to and from vagina, partially projects into vaginal lumen

internal & external uterine orifices
cervical canal
cervix (muscle)

Vagina

copulatory organ and birth canal

urethral orifice separates vagina from vestibule

Vestibule

combines reproductive and urinary organs

Vulva

ventral commissure is pointed

dorsal commissure is rounded

fossa clitoridis & clitoris (not to be confused with urethral orifice)

Placenta

temporary organ for gestation

structure is species dependent

Mammary glands

modified sweat glands responsible for lactation

number of pairs varies with the species (5 in bitches)

lymphatic drainage is relevant for surgical removal of tumors

Scrotum

protects and supports testes

dual chambered pouch separated by septum

each half contains a testis, epididymis, & distal portion of the spermatic cord

Layers (E->I): Skin & dartos, external spermatic fascia, internal spermatice fascia, parietal vaginal tunic, vaginal cavity, visceral vaginal tunic (closest to testis)

Testes

male gonads

migrate from developmental position near kidneys to scrotum

spermatogenesis and endocrine function (testosterone)

Epididymis

maturation and storage of spermatozoa

one long duct coiled, presents in three parts

Head - sperm enter from testes
Body
Tail continuous with ductus deferens (the dangly bit)

Ductus deferens

continues from the tail of the epididymis

enters abdominal cavity as part of the spermatic cord

crosses lateral aspect of the urinary bladder to enter into the pelvic urethra

Accessory glands

responsible for production of the seminal plasma

Prostate gland: surrounds pelvic urethra (can lead to urinary issues if inflamed)

Benign Prostatic Hyperplasia

BPH

enlarged prostate

common disease in intact dogs over 5 years old

Penis

male copulatory organ

root: anchored to the ischial arch

body - just vibes ig

glans - most distal aspect, consists of bulbous glandis and pars longa glandis; contains os penis

Erectile tissues

corpus spongiosum penis

corpus cavernosum penis

Os penis

visceral bone in dog dicks to provide protection

urethral groove located along the ventral aspect

Erection

brought on by the relaxation of the retractor penis muscle and erectile tissues filling with blood

tumescence

parasympathic - electrical stimulation; when discontinued ejaculation occurs

somatic system - sensory and motor neurons responsible for contraction of ischocavernous and bulbospongiosus muscles

sympathetic system- hypogastric nerve and pelvic plexus inhibitory for erection

musculocavernous

large amounts of erectile tissue: dog, stallion, horse

engorges and grows in lengths

fibroelastic

limited amounts of erectile tissue: bull, boar, ram

does not change girth

sigmoid flexure is smoothed out to "extend" length

Prepuce

fold of skin covering the glans penis
external lamina is the hair part
internal terminates at the fornix and becomes continuous with the skin of the glans

Blood vessels of le dick

internal pudendal artery and vein

deep vein and artery of penis

dorsal artery and vein of penis

Actinomycosis

Lumpy Jaw
Bovine mouth disease
Actinomycres bovis (G+ O-)
cause: abrasion/lesion of the oral mucosa
treatment to kill bacteria& stop lesion spread: sodium iodine IV & antibiotics
guarded prognosis

Actinobacillosis

Wooden Tongue
bovine mouth disease
Actinobacillus lignieresii (G-)
Treatment: IV sodium iodine, antibiotics (anti G-), and surgical debulking of lesions
prognosis good if only tongue is infected

Esophageal obstruction

Choking
Bovine Esophageal condition
caused by lack of chewing or ingestion of foreign body
treatments: tubing, corkscrew plastic trocar (life threatening cases only), or temporary rumen fistula (surgical)

Traumatic reticulo-peritonitis

Hardware disease (TRP)
Bovine reticulum condition
reticulum is perforated from the inside
Rumenotomy: reach in through the rumen to remove object as there is no access to reticulum surgically
If undiagonosed, object could move cranially and cause congestive heart failure

Traumatic Percarditis

brisket edema
TRP Congestive Heart Failure
Euthanasia

Left Displacement of Abomasum (LDA)

abdominal distension
auscultation of PING
surgical correction --> through right side flank abomasum is deflated and brought back to its anatomical location (exteriorization of the pylorus)

Omentopexy

-opexy : fixation, anchoring
omentum is attached to abdominal wall to avoid any recurrence of abomasal displacement

Hemorrhagic Bowel Syndrome

Clostridium perfingen type A (normal biota in bovine GI tract)
Aspergilluas fumigatus (fungus in feed and forages)
affects dairy cows more than beef cows
obstruction of intestinal lumen by blood clots
Treatment: surgery (manual massage of blood clots), IV fluids, and antimicrobials
guarded prognosis

Intussesception

intussusceptum: invaginated part (oral)
intussescipiens: outer layer (aboral)
looks like a bull's eye on sonograph
treatment: surgical resection of affected intestinal segment
guarded prognosis

Cecal dilation

distention without a twist
70% of cecum issues
unknown cause
presenting signs: drop in milk production/reduced appetite
Treatment: IV fluids, electrolytes, anti-inflammatory drugs, +/- antimicrobial therapy

Cecal torsion

rotation along the long axis
5% of cecum issues
unknown cause
presenting signs: severe colic, tachycardia, ruminal atony
treatment: typhlotomy or partial thyphlectomy

Cecal volvulus

dorsal retroflexion (clockwise volvulus)
ventral retroflexion (counterclockwise volvulus)
25% of cases
unknown cause
presenting signs: severe colic, tachycardia, ruminal atony
treatment: typhlotomy or partial thyphlectomy

Extracellular Fluids

(ECF) 20% of total body water
about 1% of this is transcellular water that is localized in specific places within the body
lymph in lymphatic vessels, cerebrospinal fluid in brains, synovial fluid in joints, aqueous humor and vitreous body in the eyes, endolymph and perilymph in th eears, pleural, pericardial, and peritoneal fluids between serous membranes, glomerular filtrate in kidneys

Water intake

ingested liquid
ingested food
metabolic water (water of oxidation)

Water losses

Urine
skin excretes water as sweat
lungs, as exhaled water vapor
gastrointestinal tract, in feces

Nephron

the functional unit of the kidney
cannot be replaced, only partially regenerated
two types of nephrons
in humans about 1 million per kidney; cows about 4 millions; dogs 400,000; cats 190,000

Cortical nephrons

Glomerulus located far from the cortex/medulla junction Short loops of Henle
Blood supply by peritubular capillaries

Juxtamedullary nephrons

Glomerulus located near the cortex/medulla junction
Efferent arterioles give rise to long straight capillaries (vasa recta) that descend into the renal medulla
Extremely long loops of Henle (critical for urine concentration!)

Renal Corpuscle

Malpighian body
located in the renal cortex, consists of glomerulus (capillaries) sorrounded by Bowman‘s capsule (double-walled capsule)

Proximal tubule

the longest part of the nephron (ca. 10 mm), consisting of a proximal convoluted (PCT) and a straight part (PST)

Reabsorbs most filtered solutes
e.g. glucose, amino acids, peptides,
proteins, Na+, K+, Cl-, HCO3 - Ca ++, Mg++ Reabsorbs water
Excretion of wastes

The loop of Henle

consists of a thick descending limb (extending into the renal medulla), a thin descending limb, a thin ascending limb (ONLY in nephrons which have long loops!), and a thick ascending limb (TAL, macula densa!)

Thin Limbs of Henle's Loop

Reabsorbs water, Na+, Cl-

Thick ascending limb

Reabsorbs Na+, K+, Cl-

Distal convoluted tubule

Reabsorbs Na+, Cl-, Ca ++, Mg++ Regulate acid, bicarbonate, ammonia, and water excretion

Collecting Ducts

Regulates acid, bicarbonate, ammonia, Na+, K+, and water excretion

The distal tubule

convoluted part (DCT) and straight (DST)

The collecting ducts (CD)

extend through the renal cortex and medulla

Glomerular Filtration

The first step in urine formation is the filtration of large amounts of fluid through the glomerular capillaries into Bowman‘s capsule
Most (99%+) of this is reabsorbed, leaving less than 1 liter to be excreted (highly variable)

Glomerulus

is a compact network of capillaries that retains cellular
components and proteins (medium-to-high-molecular weight proteins)
semipermeable membrane is key

Filters the blood and forms the primary urine

Primary Urine

The ultra filtrate that accumulates in the
capsular space between glomerulus and Bowman's capsule (Bowman’s space).
Contains the same concentration of salt and glucose as plasma

Tubular fluid

Filtrate inside the tubular system
In its passage through the nephron’s tubular system, the tubular fluid is being continuously modified by tubular reabsorption and becomes “final urine”
Tubular reabsorption recovers most filtered substances (100% of glucose, 99% of H2O, Na+, Ca2+, Cl-, HCO3-)

Glomerular FIlterability

Filterability of substances by glomerular capillaries based on molecular weight (a proxi of size)
electrolytes such as sodium and small organic compounds such as glucose are filtered as freely as water

Electrical charge

Cationic (+) substances are more easily filtered than anionic (-) substances. This due to the negative charge of the glomerullar basement membrane

Plasma protein binding

This can be seen as a protective mechanism for some solutes such as calcium. Some drugs will be retained in the circulation for a defined time period before being eliminated

Osmolality

is the number of osmoles of solute per kilogram of solvent
because volume is temperature-dependent, osmolality is more suitable in living organisms (Osm/Kg water)

Glomerular Capillary Hydrostatic Pressure

The main driving force for filtration is the glomerular capillary hydrostatic pressure

The forces opposing filtration are the hydrostatic pressure in Bowman‘s space and
the oncotic pressure of the blood plasma

The oncotic pressure of the filtrate is essentially
non-existent

Functions of the Kidney in water balance

maintain the water content of the body and plasma tonicity (extracellular osmolality)

do so by concentrating the urine and reabsorbing water so we dont need to drink as much water to survive

How is water reabsorbed in the kidneys?

PT reabsorbs water through aquaporins (AQP‘s) and solute reabsorption. Additionally, Na+ reabsorption favors the movement of water into the cells and into the interstitium as well
- The thin descending limb of Henle‘s loop reabsorbs water by osmosis
...And finally, the collecting ducts do the last big water reabsorption (adjustable by ADH-sensitive AQP‘s)

Serum urea and serum creatinine

a lab parameter measured to evaluate kidney function

• Predominantly dependent on the glomerular filtration rate
(GFR)
• Provide an estimation of GFR = flow of plasma from the glomerulus into Bowman’s space over a specified period

Urine specific gravity (USG)

a lab parameter measured to evaluate kidney function

• Provides an estimation of urine osmolality
• Index of tubular reabsorption = kidney's "response ability" to concentrate (remove water in excess of solute) or dilute (remove solute in excess of water) urine

Acute Kidney Injury

Abrupt damage to the renal parenchyma resulting in reduction in kidney function reflected by alterations in glomerular filtration, urine production and tubular function (acute renal failure)

• Retention of uremic wastes that may lead to azotemia
• Deranged fluid status, electrolyte imbalances and acid-base disorders

Pre-renal (hemodynamic)

Insufficient delivery of blood to the kidneys

Dehydration, hypovolemia, hypotension, decreased effective circulating volume, trauma, shock, drugs (NSAIDs, ACEi), etc.

Reversible provided compromised renal perfusion is corrected before the onset of ischemic nephron damage

> Elevated serum BUN or creatinine concentrations
> Oliguria
> High urine specific gravity (1.035 in dogs; 1.040 in cats) > Detection of underlying cause
> Rapid correction of azotemia after administration of appropriate therapy to restore renal perfusion

Intrinsic renal

Damage to any section of the kidney:
Glomeruli, tubules, interstitium, or vessels

Ischemia, toxins, infectious, immune- mediated, neoplasia, etc.

Intrarenal azotemic renal failure may be caused by many disease processes that destroy ≥ 3⁄4 of the parenchyma of both kidneys

> Dehydrated/Hydrates patient, with increased BUN and creatinine and impaired ability to concentrate urine.
> More definitive studies (e.g., ultrasonography, radiography, biopsy, exploratory surgery) to establish the underlying cause
> Azotemia does not resolve after appropriate therapy

Total inability of the nephrons to concentrate or dilute urine (isosthenuria) results in the formation of urine that is similar to that of glomerular filtrate (approximately 1.008 to 1.012)

Post renal

Urine leakage within tissue or urinary obstruction

Trauma, calculi, mucous plugs, tumors, blood clots, urethral/ureteral strictures

Reversible provided compromised renal perfusion is corrected before the onset of ischemic nephron damage

Obstruction or Rupture

Obstruction of the excretory pathway

> Elevated serum BUN and creatinine concentrations
> Oliguria or anuria, dysuria and tenesmus
> Obstructive lesions detected by physical examination (e.g., urethral plug, herniated bladder), radiography, ultrasonography, etc.
> Variable urine specific gravity values

obstruction for longer than 3 days = death

long term prognosis depends on reversibility of underlying cause

Rupture of the excretory pathway

> Progressively elevated serum BUN or creatinine concentrations
> Progressive depression, painful abdomen, ascites
> A history of trauma and associated physical examination findings
> Inability to palpate the urinary bladder
> Detection of a modified transudate or exudate by abdominocentesis
> Abnormalities detected by ultrasonography or retrograde contrast (positive or negative) cystography or urethrocystography.

long term prognosis depends on reversibility of underlying cause

azotemia

a condition that occurs when your kidneys have been damaged by disease or an injury

Phase 1 Initiation

Renal insult (Ischemic,nephrotoxic,obstructive)

Direct damage to renal tubular cells and ischemia

Hypoxia -> depletion in ATP -> increased cellular calcium concentration -> activates proteases and phospholipases -> ROS and free radicals ->cellular damage -> inflammatory reaction

Phase 2 – extension phase

Amplification of the initial renal insult by ongoing hypoxia from ischemia and the resulting inflammatory response

When clinical signs appear

lack of baseline may make detection tricky, intervention not always successful at this stage

Phase 3 – maintenance phase

In this stage, a critical amount of irreversible damage has occurred - stabilization of the GFR at its nadir

Apoptosis continues but renal blood flow returns to normal, leading to cellular repair

Proliferation and migration of renal tubular cells occurs, beginning the process of re-establishing cell polarity and tubular integrity

AKI is usually detected in this stage

Phase 4 – recovery phase

GFR rises as cellular repair continues

Very important to avoid any additional renal injury during this period

What are the effects of early spay/neuter?

prevents mammory cancer

prevents puppies

neutering prevents roaming males

Decreased metabolism

failure to achieve full development

can become incontinent

Concentrations of LH and FSH in dogs that have been spayed are ____

increased as there is nothing being produced to trigger the negative feedback

How does progesterone work as a contraceptive?

stops the cycle because it is a pro-pregnancy hormone

side effects mammary enlargement and pyometra

How would an androgen work for contraception in female dogs?

Increase aggression

Increase muscle mass

Immunosterilization

Can vaccinate against GnRH to prevent fertilization