27 Aug 2018
Francesco Cian
Job Title
This image is from a urine sediment from an adult male cat with acute history of vomiting and oliguria. Urinalysis and selected biochemistry results are provided in Table 1.
| Table 1. Urinalysis and biochemistry | ||
|---|---|---|
| Biochemistry | Result | Reference interval |
| Urea (mmol/L) | 20.4 | 7.1 to 10.7 |
| Creatinine (umol/L) | 260 | 0 to 140 |
| Urinalysis | ||
| Urine specific gravity | 1.015 | >1.035 |
| pH | 5.8 | 5.5 to 7.5 |
| Bilirubin | Negative | Negative |
| Blood | + | Negative |
| Glucose | + | Negative |
| Protein | +++ | Negative |
| Urine protein:creatinine ratio | 4.5 | <0.2 |
The image is a photomicrograph at high power (50×) of the unstained urine sediment.
What is your interpretation?
The evidence of poorly concentrated urine, in association with azotaemia and oliguria, are supportive of decreased glomerular perfusion rate due to renal disease. Glucosuria and proteinuria are also present, suggesting an existing tubular damage.
On sediment analysis, no signs of inflammation exist; however, large numbers of casts are seen.
Casts are cylindrical moulds that form in the lumen of renal tubuli. They are made of a mucoprotein matrix, with or without cells, or cellular debris. Increased casts formation (cylindruria) can occur in association with kidney disease. In this particular case, the majority of the casts were granular casts. Granular casts contain variably sized and shaped cell fragments and are the result of an acute renal insult, which can damage the tubular cells. This causes the cell fragments to be incorporated in the mucoprotein matrix and to form the casts.
In this case, the owner reported seeing the cat chewing a few leaves of a white lily flower (Lilium longiflorum) and vomiting within two hours of ingestion. Most pet owners know little about the danger these plants pose to cats. In fact, although cats are finicky eaters, for an unknown reason they eat leaves and flowers of lilium plants. Both leaves and flowers are reportedly toxic and the ingestion of one or two leaves or one whole flower may cause toxicosis.
The toxic compound contained within this flower is reported as being particularly nephrotoxic to the feline species, and causing acute tubular necrosis. Dialysis has been used in the management of lily toxicity in cats and shown to improve outcome in several nephrotoxicoses.
The mortality rate from lily toxicosis is reported to be as high as 50% to 100%, depending on the time symptomatic treatment is initiated. High mortality rate is reported if treatment is not initiated before onset of anuric renal failure, which occurs 18 to 24 hours after exposure.
