Crystals

Question 1

Calcium

Oxalate

Dihydrate

Answer 1

• “Envelope” shaped
• Forms in acidic urine
• Occurs normally in many species
• Occurs in animals with uroliths

Question 2

Calcium

Oxalate

Monohydrate

Answer 2

• Vary in size and shape
• Ovals, dumbbells, spindles, or picket fence slat
• Associated with ethylene glycol toxicity

Question 3

Struvite

AKA

Triple Phosphate

Answer 3

• “Coffin” like prisms
• Form in alkaline to neutral urine
• May assume a fern-leaf shape, especially when the urine contains a high concentration of ammonia

Question 4

Amorphous

Urates

Answer 4

• Granular precipitate
• Seen in acidic urine

Question 5

Calcium

Phosphates

(Amorphous)

Answer 5

• Forms in alkaline urine

Question 6

Ammonium

Urate

AKA

Ammonium Biurate

Answer 6

• Seen in slightly acidic, neutral, or alkaline urine
• Brown in color and round with long irregular spicules (“thorn apple” shape)
• Most commonly seen in animals with severe liver disease and portal vascular anomalies

Question 7

Cystine

Answer 7

• Thin, transparent, colorless hexagonal rings
• Single or aggregate in layers
• Forms in concentrated acidic urine
• Can be associated with renal tubular dysfunction or cystine urolithiasis

Question 8

Bilirubin

Answer 8

• Yellow to reddish brown needles or granules
• Can be seen in highly concentrated normal dog urine
• Abnormal bilirubin metabolism