honestly probably not as complete but still good to look at
Urinalysis
The first step in performance of a urinalysis is proper collection of a urine sample, which must be obtained carefully to ensure meaningful results. Four basic methods exist for collection of a urine sample:
1. Cystocentesis
2. Catheterization
3. Expressing the bladder
4. Natural voiding of the urine (urination)
Normal Urine Output/day in ml/lb:
Dog 12-30
Cat 4.5-9
Cattle 8-20
Horse 2-8
Swine 2-14
Sheep, Goat 4.5-18
The normal yellow color of urine is due to the presence of pigments called urochromes.
Colorless urine has a very low specific gravity.
Dark yellow to yellow-brown urine generally has a high specific gravity.
Yellow-brown to greenish urine that produces a greenish yellow foam when shaken is likely to contain bile pigments.
Red or reddish-brown urine indicates the presence of RBC's, called hematuria or hemoglobin, called hemoglobinuria.
brown pee when voided may contain myoglobin (myoglobinuria) excreted during conditions that cause muscle cell lysis, such as exertional rhabdomyolysis in horses.
Some drugs may alter the color of urine; red, green, or even blue urine may be observed.
Horse pee is normally cloudy, other species should have clear pee
Transparency is noted as clear, cloudy, or flocculent.
Cloudy samples usually contain large particles, and they yield a lot of sediment on centrifugation.
Substances that cause urine to be cloudy include RBC's, WBC's, epithelial cells, casts, crystals, mucus, fat and bacteria. Flocculent samples contain suspended particles that are sufficiently large to be seen
SpG specific gravity= weight (density) of a quantity of liquid as a compared w/that of an equal amount of distilled water
pH of standing open pee at room temperature will increase due to loss of CO2
- Alkaline pee found in pets on plant diets
- Acidic pee found in pets on high protein cereal diets or diets made of animals
- Nursing herbivores have acidic pee from consuming milk
PH
- Decreased pH may be due to things, like fever, starvation, high protein diet, acidosis, excessive muscular activity, or administration of certain drugs.
- Increased pH may be caused by alkalosis, infection of the urinary tract with urease bacteria, use of certain drugs, or by urine retention, as occurs with urethral obstruction or bladder paralysis.
Protein
The relationship of any protein measured in the urine and possible leakage through the renal glomeruli must be interpreted in light of the urine SpG, collection method, rate of urine formation, and contributions from any hemorrhage or inflammation noted by sample analysis.
- Very dilute pee may cause false neg results because protein concentration may be below sensitivity of test
- Trace protein in pee with a super dilute sample may be important to dr b/c dilute pee happens when a lot of pee is being made like in a pet w/ chronic renal failure (CKF)
○ Usually proteinuria (protein in pee) tells us there's some kind of disease in the urinary tract especially in the KIDNEYS
○ Both chronic and acute kidney disease leads to this
○ Mild proteinuria is seen w/passive congestion of the kidneys like congestive heart failute or any other impediment of blood flow from the kidneys
§ Inflammation of urinary or genital tract may cause proteinuria of post renal origin it may also be seen w. traumatic catheterization
Gluocse
- Glucosuria happens in diabetes mellitus high carb meal may lead to BG levels exceeding renal threshold
○ Fear, excitement or restraint (especially in cats) occasionally cause hyperglycemia and glucosuria as a result of epinephrine release
§ Rarely glucosuria is found in hyperthyroidism, cushings, and chronic liver disease
○ FALSE POS may be seen after using many drugs including vit C, morphine, salicylates (like asprin), cephalosporins and penicillin
Ketones
- Ketones: acetone, acetonacetic acid, and beta hydroxybutyric acid.
- Ketone bodies are made during incomplete catabolism of fatty acids.
○ Its normal to have a small amount of these in the blood
- Conditions characterized by altered carbohydrate metabolism may result in excessive amounts of fat catabolism to provide energy.
- When fatty acid metabolism is not accompanied by enough carbohydrate metabolism, excess ketones spill into the urine, (ketonuria).
- Common CAUSE of ketonuria=ketonemia or ketosis in lactating cows & pregnant ewes + cows
- Ketonuria happens often in animals w/diabetes mellitus, high fat diets, STARVATION, fasting, long term anorexia and impaired liver function
Bile pigments
- Common ones found in pee are BILIRUBIN and UROBILINOGEN
○ Normal dogs (esp. males) sometimes have bilirubin in their pee, normal cattle also have a small amount in their pee
○ NOT USUALLY FOUND IN THE PEE OF NORMAL CATS, PIGS, SHEEP & HORSES
- Bilirubinuria seen in many diseases like obstruction of bile flow from liver to small intestine & some diseases of the liver.
○ Hemolytic anemia may also cause bilirubinuria especially in dogs
- In intestines BACTERIA convert bilirubin to sterobilinogen & urobilinogen. Bulk of these products is excreted in the poop but some is reabsorbed into the blood and excreted by the liver into the intestinal tract
- Sm amount of resorbed urobilinogen is excreted by the kidneys into pee
○ UROBILINOGIN IN PEE SAMPLE IS NORMAL
○ Screening for this is questionable due to instability of urobilinogen
Blood
- Tests for blood in pee detect hematuria (presence of intact RBC in pee), hemoglibinuria (presence of free hemoglobin in pee), & myoglobinuria (presence of myoglobin in pee)
- Hematuria is usually sign of disease causing bleeding somewhere in the urogenital tract or some systemic conditions vs hemoglobinuria usually means INTRAVASCULAR hemolysis
- In super dilute or highly alkaline pee, hemoglobinuria may NOT be due to hemoglobin entering the urine via glomerulis
○ Ghost cells (shed shells of lysed RBC) may be seen if the source of hemoglobin in lysis of RBC
• Red, brown or wine color, but with a transparent appearance that remains after centrifugation, indicates hemoglobinuria.
- With minute amounts of blood in the urine, a visible color change is not evident.
• Hemoglobinuria usually is due to intravascular hemolysis.
• Hemoglobin from RBC's broken down intravascularly, or hemoglobinemia, is normally bound to the plasma protein haptoglobin.
• When hemoglobin is bound to haptoglobin, it DOESN'T pass through glomeruli.
- If intravascular hemolysis overwhelms haptoglobin's binding ability, hemoglobinemia leads to hemoglobinuria because free hemoglobin filters through glomeruli.
- When hemoglobin concentration is sufficiently high in the urine to impart a red discoloration, the urine remains red after centrifugation.
- If discoloration is due to RBC's, the urine is clear above the pellet after centrifugation. Partial clearing after centrifugation indicates both hemoglobinuria and hematuria.
- Hemoglobinuria can be seen with many conditions that cause INTRAVASCULAR HEMOLYSIS
○ Things that cause intravascular hemolysis are IMHA, isoimmune hemolytic disease of neonates, incompatible blood transfusion, lepto, babesiosis, some heavy metals (copper) and eating poisonous plants
- Other conditions that cause hemoglobinuria are sever hypophosphatemia, postparturient hemoglobinemia in cattle, and hemolysis of cattle that occurs after they drink large quantities of H20 after being unable to obtain water.
Myoglobinuria
- Myoglobin is a protein found in muscle, severe muscle damage causes myoglobin to leak from the muscles into the blood
- Myoglobin passes through the glomeruli & is excreted in the pee. Pee that has myoglobin is very dark brown almost black but at low concentrations pee may have similar color seen w/hemoglobin (blood)
- Distinguishing myoglobinuria from hemoglobinuria is hard.
○ History and clinical features that suggest muscle damage help determine if a positive hemoglobin test is due to myoglobin.
○ Myoglobinuria is frequently seen in horses with exertional rhabdomyolysis (azoturia).
- Several methods have been used to try to distinguish hemoglobin from myoglobin. None of these methods are completely reliable.
Nitrate
- Some bacteria contain enzymes that reduce nitrate to nitrite in the urine. The presence of nitrite in urine suggests bacteriuria. However, a negative nitrite test does not indicate that bacteria are absent. Microscopic exam should be done to see bacteria in pee
Leukocytes
- WBC in pee may be got w/ leukocyte reaction of some strips, false neg may happen
- Microscope eval may be necessary
Microscope evaluation
- MUST be part of every urinalysis
- With the exception of horse pee, normal urine of domestic animals doesn’t have a large amount of sediment.
- Small numbers of epithelial cells, mucus threads, RBC's, WBC's, hyaline casts, and crystals of various types can be found in the urine of normal animals.
- The urine of horses usually has large amounts of calcium carbonate crystals.
- The best samples for sediment examination are morning samples, or samples collected after several hours of water deprivation. Because such samples are more concentrated, chances of finding formed elements are increased
- If voided sample got, midstream sample is best since its not as likely to be contaminated by cells, bacteria, and debris from external genial surfaces
- Cysto is the best tbh
Procedure
- Place 5 ml of a well mixed sample in a graduated, conical centrifuge tube and centrifuged for 3-5 minutes at 1000-2000 rpm.
- Excessive force compacts the sediment and may distort or disrupt formed elements. After centrifugation, the volume of sediment is recorded, and the supernatant is gently poured off, leaving about 0.3 ml of urine adhered to the sides of the tube.
- This remaining urine is allowed to run down the inside of the centrifuge tube, and the sediment is resuspended by gently flicking the bottom of the tube with your finger.
- To examine unstained sediment, a small drop of the suspended sediment is placed on a clean glass slide, covered with a coverslip, and examined immediately.
- Subdued light that partially refracts the elements must be used to examine unstained urine sediment. Proper lighting is achieved by partially closing the microscope's iris diaphragm and adjusting the condenser downward.
- Satisfactory stains include Sternheimer-Malbin stain (Sedi-stain) or 0.5% new methylene blue containing a small amount of formalin.
- One drop of stain is mixed with suspended sediment before placing a drop on the slide. The amount of illumination is less critical when examining a stained specimen than with an unstained one.
The specimen is scanned under low power (10X) to gain an impression of what is present and to identify larger elements, such as casts or aggregates of cells. The entire area under the coverslip should be examined because casts tend to migrate toward the edge of the coverslip. Casts and crystals are identified and reported as the number observed per low- power field (LPF). High power (40X or 50X oil immersion) is necessary to accurately identify most objects, to detect bacteria, and to differentiate cell types. Epithelial cells, RBC's, and WBC's are reported as the average number observed per high power field (HPF). Bacteria and semen are reported as + (less than 1/HPF), ++ (1-5/HPF), +++ (6- 20/HPF), ++++ (Greater than 20/HPF), and their morphology (cocci, bacilli) is noted.
Parts of the Urine sediment
Erythrocytes/RBC
- RBC can look many different ways depending on urine concentration, pH and time elapsed btween collection and exam
- In FRESH sample RBC usually have smooth edges and look yellow to orange but may b colorless if they hemoglobin has diffused during standing
- In CONCENTRATED pee RBC shrink and crenate (ruffled edges and darker)
- In DILUTE alkaline pee, RBC swell and may lyse, smooth rbc w/ pale yellow or orange
- Lysed rbc may be colorless rings (shadow/ghost cells) that vary in size
- Normally pee sediment has less than 2-3 RBCs/HPF
- The slightest trauma from catheterization, cystocentesis, and manual expression of the bladder may slightly increase the number of RBC's in the sediment.
Leukocytes
- Few WBC are normally found in animal pee w/out urinary or genital tract disease
- Leukocytes are spherical and have a granular appearance; they are larger than RBC's & smaller than renal epithelial cells.
○ The granular appearance is b/c most WBC's in urine are neutrophils, which have lots of granules.
- Finding more than 2-3/HPF means inflammation somewhere in the urinary or genital tracts.
- Pyuria: excessive WBC's in the urine is.
- Pyuria is indicative of nephritis, pyelonephritis, cystitis, urethritis, or ureteritis. Urine with increased numbers of leukocytes should be cultured for bacteria even if organisms are not observed by microscopic examination.
Epithelial Cells
Squamous Epithelial
- From distal urethra, vagina, vulva, or prepuce & are sometimes found in voided samples
- Their presence doesn’t mean much
- These flat cells with a homogenous appearance are the largest cells found in urine sediment. They often have straight edges and distinct comers. They may show a small round nucleus. Squamous epithelial cells are not normally found in samples obtained by cystocentesis or catheterization
Transitional epithelial
- These cells come from the bladder, ureters, renal pelvis, and proximal urethra. They are usually round, but they may be pear shaped or caudate. They are granular, have a small nucleus, and are larger than WBC's. Occasional transitional cells (0-1/HPF) may be found in urinary sediment as a result of sloughing of old cells, but and increased number suggests cystitis or pyelonephritis. Increased numbers also may be seen if catheterization was used to obtain a sample. Clumping of these cells may point toward neoplasia and should be noted.
Renal Epithelial
- These are the smallest epithelial cells seen in urine. They originate in the renal tubules, are only slightly larger than a WBC, and are often confused w/them. Renal epithelial cells are generally round and contain a large nucleus and non-granular cytoplasm.
- They are rarely found (0-1/HPF). Increased numbers of these cells occur in diseases of the kidney parenchyma.
Microorganisms
- Bacteria are minute and can be identified only at higher magnifications. They may be round (cocci) or rod shaped (bacilli), usually refract light, and appear to be quivering as a result of Brownian movement.
- Fungi are filamentous and usually branching. Septa may be seen when the microscope is optimally adjusted. Fungal infections of the urinary tract are uncommon, but they are very serious when they occur.
Casts
- formed in the lumen of the distal & collecting tubules of the kidney, where the concentration and acidity of urine are greatest.
- In the renal tubules, secreted protein precipitates in acidic conditions form casts shaped like the tubules in which they are made.
- All casts are cylindric, with parallel sides. Cells in the area also may be incorporated into casts, imparting the morphologic features that allow them to be identified specifically.
- Casts dissolve while in alkaline urine, so cast identification and quantitation are best performed in fresh samples that have not become alkaline with standing.
- b/c casts dissolve quickly in alkaline urine they are rarely seen in the sediment of herbivores, which characteristically have alkaline urine.
- A few hyaline casts or granular casts (0-1/HPF) may be seen in normal urine, but larger numbers of casts indicate a lesion in the renal tubules. The number of casts observed is not a reliable indicator of the severity of the urinary disease.
Hyaline Casts
- Few can be seen in normal pee. They're clear, colorless & highly refractile. Hard to see and usually only seen w/ dim light
- Hyaline casts are cylindric w/ parallel sides & usually rounded ends, easier to ID in stained sediment
- Increased # of these can mean theres a mild form of renal irritation, they numbers r also increased w/fever, poor renal perfusion, strenuous exercise or general anesthesia
Granular Casts
- Super common, these are just hyaline casts with granules
- These granules r from tubular epithelial cells & WBC that became incorporated in the cast & then degenerated
- They are seen in Lg numbers w/ ACUTE nephritis & indicate more severe kidney damage
Epithelial Casts
- Made of epithelial cells from the renal tubules
- Epithelial cells in in casts always are epithelial type b/c this is the ONLY epithelial cell present at the site of cast formation granular casts r usually with em
- These casts are seen in acute nephritis or other conditions that cause degeneration of the renal tubular epithelium
Leukocyte Casts
- Has WBC, usually accompanied by free WBX
- Presence of WBC and leukocyte casts mean inflammation in renal tubules
Erythrocyte casts
- Deep yellow to orange, RBC may or may not B visible
- Erythrocyte casts can mean RENAL BLEEDING
- Bleeding may be strictly from hemorrhage resulting from trauma or bleeding disorders, or it may occur as part of an inflammatory lesion.
Waxy casts
- Resemble hyaline casts but r wider w/ square ends rather than round ends & a dull, homogenous, "waxy: appearance, more opaque than hyline casts
- Indicate chronic, severe degeneration of renal tubules
Fatty Casts
- Has small droplets of fat that appear as refractile bodies, usually seen in cats w/ renal disease b/c cats have lipid in their renal parenchyma
- Occasionally seen in dogs w/ diabetes mellitus
- Lg # of fatty casts suggest degeneration of renal tubules
Mucus Threads
- resemble a twisted ribbon more than a cast.
- A large amount of mucus is normally present in equine urine because horses have mucus glands in the renal pelvis and ureter. In other animals, mucus indicates urethral irritation or contamination of the sample with genital secretions.
Sperm. They are there. Sperm does not come from kidney. Not relevant.
Parasite Ova, Microfilariae
- Parasite ova may be seen in the urine sediment of animals with urinary parasites or because of fecal contamination at the time of collection of the urine sample.
- Parasites of the urinary tract include Capillaria plica, a bladder worm of dogs and cats; Dioctophyma renale, a kidney worm of dogs; and Stephanurus dentatus, a kidney worm of pigs.
Microfilariae may be seen in the urine sediment of dogs with adult heartworms and circulating microfilariae. Hemorrhage into the urine occurs either from disease of, or as a result of trauma during collection.
Fat droplets
- Lightly green-tinged, highly refractile, spherical bodies of different sizes
- Due to size difference they can be distinguished from RBC and yeast
- If a sediment smear is allowed to sit for a few moments b4 its examined, fat droplets rise to a plane just beneath the coverslip while other formed elements settle to the top of the slide so fat is usually not in focus
- Small, round structures found under the coverslip are usually fat globules.
- In sediment stained with Sudan III, fat droplets appear orange or red.
- usually, fat droplets from catheter lubricants or from oily surfaces of collecting vials and pipettes may contaminate urine.
- Lipuria=fat in urine kinda seen in most cats. Lipuria also is seen with obesity, diabetes
mellitus, and hypothyroidism, and rarely after a high-fat meal
Crystals
- Crystalluria=Presence of crystals in pee
- May or may not be of clinical significance
- Some crystals form due to metabolic diseases. Conditions that lead to crystal formation may also cause formation of urinary calculi.
- The type of crystals formed depends on the urine pH, concentration and temperature, and the solubility of the elements.
- If a urine sample is allowed to stand and cool before examination, the number of crystals in the sample increases because the materials that make up crystals are less soluble at lower temperatures.
- Refrigerated samples often have more crystals than warm, fresh samples. Sometimes crystals dissolve when a refrigerated sample is warmed to room temperature.
○ Crystals are generally reported as occasional, moderate, or many.
Triple Phosphate (Struvite)
- found in alkaline to slightly acidic urine.
- Generally struvite crystals are eight-sided prisms, with tapering sides and ends.
- Triple phosphate (Struvite) crystals typically are described as resembling coffin lids, although they may assume other shapes. Occasionally they may assume a fem-leaf shape, esp. when the urine contains a high concentration of ammonia.
Amorphous Phosphate
- These crystals are common in alkaline urine and appear as a granular precipitate.
Calcium Carbonate
- these crystals, commonly seen in the pee of horses, are round, with many lines radiating from their centers.
- may have a "dumbbell" shape.
Amorphous Urates
- Amorphous urates appear as a granular precipitate similar to amorphous phosphates.
- seen in acidic urine.
Ammonium Biruate
- these crystals are round and brownish, w/long spicules (thorn apple shape).
- Often the spicules fracture and the remaining crystal is brown with fine radiating lines.
- They are most common in animals with severe liver diseases, such as portacaval shunts.
Calcium Oxalate
- Calcium oxalate dihydrate crystals generally look as small squares, containing an X across the crystal, resembling the back of an envelope.
- Calcium dihydrate crystals are found in acidic and neutral urine and are commonly seen in small numbers in dogs and horses.
- Calcium oxalate monohydrate crystals may be small and dumbbell shaped or they may be elongated and pointed at each end (resembling a slat from a picket fence).
- The urine of animals poisoned w/ethylene glycol (antifreeze) often has large numbers of calcium oxalate crystals, esp. calcium monohydrate crystals.
- Animals with oxalate urolithiasis may have large numbers of calcium oxalate crystals in their urine, and large numbers of oxalate crystals may indicate predisposition to oxalate urolithiasis.
Sulfonamide
- Sulfonamide crystals may be seen in animals being treated w/sulfonamides.
- These crystals are round, usually dark, with individual crystals radiating from the center.
- They are less likely to be observed in alkaline urine because these crystals are more soluble in alkaline mine.
- Prevention of precipitation of these crystals in the renal tubules is assisted by maintenance of alkaline urine and encouraging the animal to drink.
Leucine and Tyrosine
- Animals with liver disease may have leucine and tyrosine crystals in their urine. Tyrosine crystals are dark and needlelike.
- found in small clusters.
Cystine
- Cystine crystals appear as six-sided (hexagonal), flat plates and can be associated with renal tubular dysfunction or cystine urolithiasis.
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