Urine sediment in a cat: when the danger hides in the house!

Lucia Sanchini, DVM, MSc, Dip. ECVCP, FRCPath, MRCVS, EBVS Specialist in Veterinary Clinical Pathology. BattLab, UK.

 

 

SIGNALMENT AND HISTORY

A 7 year-old male neutered DSH cat was presented to the out of hours service for acute onset of vomiting and oliguria. The patient was a strictly indoor cat with a limited access to the balcony.

PHYSICAL EXAMINATION:

On clinical examination, the cat was dehydrated, depressed, hypothermic and drooling. He had tacky mucous membranes and in the consult room he retched several times. On palpation there was no evidence of abdominal pain, only a mild discomfort in the gastric area.

INVESTIGATIONS:

The following table reports the results of biochemistry and urinalysis performed during the emergency consultation.

What is your interpretation of these results and the most likely diagnosis?

INTERPRETATION OF THE RESULTS

There was moderate azotaemia with isosthenuric urine. These findings, combined with the dehydration of the patient, ruled out pre renal azotaemia and pointed towards renal disease. Glucosuria with glycaemia within reference range suggested tubular disease, which was confirmed by marked proteinuria with severely increased Urine Protein: Creatinine ratio.

The examination of urine sediment revealed high numbers of granular casts, with no evidence of inflammation. These cast often contained epithelial cells embedded within the protein material.

Low numbers of granular casts are considered a normal finding in urine sediment of healthy animals, however when they are so markedly increased they indicate renal tubular injury. Moreover, the presence of numerous epithelial cells is due to dead epithelial cells sloughed from the renal tubules when severe renal tubular injury occurs.

DIAGNOSIS

Acute renal failure due to tubular damage.

TREATMENT AND FOLLOW UP

Given the severity of tubular damage, the owner was questioned about a potential lily exposure. He reported that  the cat was seeing playing with a plant of white lily flower (Lilium longiflorum)  the previous afternoon, then he remained hidden for several hours until he was seeing vomiting copiously.

The cat was treated with aggressive fluid therapy and for 24 hours and he showed mild signs of improvement. Repeated Urea and Creatinine results revealed minimal decrease of both renal markers (Urea 15.6 mmol/L, creatinine 240 umol/L) but the urine output remained minimal. On the second day of hospitalization, the cat started vomiting again, the temperature dropped to 34.5 C and he started seizing. Despite several attempts of resuscitation, unfortunately he died.

DISCUSSION

Lilies are popular ornamental plants mainly sold for indoor use, which makes indoor-only house cats more at risk of intoxication, although cat owners are very often unaware of lily toxicity. Cats appear to be very sensitive to lily poisoning and no age, sex or breed predisposition has been identified. All parts of the plant are toxic— petals, stems, leaves, and pollen. The precise toxic dosage of lilies in cats is unknown, but it has been reported that ingestion of as little as 1 or 2 leaves or a whole flower  can elicit toxicosis. The nephrotoxic compound present within lilies is rapidly absorbed and it leads to acute renal tubular epithelial cells necrosis. The first clinical signs are salivation, vomiting, anorexia, and depression and they typically develop within 1 to 3 hours post ingestion. Development of polyuria occurs 12 to 30 hours after ingestion, followed by a resultant dehydration. The anuric phase begins from 24 to 48 hours into the syndrome and it is generally associated with high mortality rate. Aggressive fluid therapy must be administered within the first 24 hours after ingestion and before the development of anuria. This fluid diuresis must be maintained for 24 to 72 hours, accompanied by serial serum chemistry panels and urinalysis to assess both the level of kidney failure and the response to therapy. At present, only peritoneal dialysis and haemodialysis are effective forms of treatment once anuric renal failure has developed. The prognosis depends on the severity of clinical signs, time of presentation and establishment of acute anuric renal failure.

Preventing exposure of cats to houseplants is the most effective method to ensure their safety and cat owners should be aware if the plants in their household may have potential toxic effects on their animals.