Plus-Hex CLINICAL
Patient signalment
Species Breed Age Sex Weight
Presentation
Cat Domestic shorthair 2 years Male, neutered 4.46 kg
A 2-year-old male neutered domestic shorthair cat( not pictured) presented with a history of 3 days of anuria and 2 days of vomiting, followed by inappetence and lethargy. These clinical signs are common in cats with a urinary obstruction [ 1 ].
On triage, the urinary bladder was palpated and found to be large, firm, painful and unable to be expressed with gentle pressure. The cat ' s pain score was 3 / 4 on the Feline Acute Pain Scale [ 2 ]. Feline urethral obstruction was immediately suspected.
A body weight of 4.46 kg and body condition score of 5 / 9 using the World Small Animal Veterinary Association( WSAVA) [ 3 ] scale were recorded. The patient was very anxious, hissing and trying to escape.
Assessment and admission
Urethral obstruction is a life-threatening emergency [ 4 ]. Cats with suspected lower urinary tract disease should immediately be triaged and have their bladder palpated. On triage, in line with best practice and following the practice ' s standard protocol, the owner ' s consent for analgesia was obtained, an intravenous( IV) catheter was placed and blood tests were performed to help assess the patient ' s condition.
Male cats have narrower and longer urethras than females and are more likely to develop an obstruction [ 1 ]. In this patient, the cause was a urethral plug, resulting from a build-up of proteins, cells, crystals and debris in the bladder that moved and became lodged in the urethra [ 5 ].
Blood chemistry and blood gas analysis should be prioritised to assess the severity and likely outcome, to help to stabilise the patient [ 6 ]. Hyperkalaemia, if not corrected with fluids, can cause shock and death [ 7 ]. Azotaemia triggers nausea and inappetence [ 8 ]. Metabolic acidosis can cause reduced renal and hepatic blood flow [ 9 ]. Therefore, the patient ' s biochemistry must be stabilised prior to the unblocking procedure.
This patient was tachycardic, with a heart rate of 248 bpm, which could suggest hyperkalaemia [ 6 ] or pain and distress. However, electrocardiogram( ECG) changes can be due to patient variables rather than being dependent on serum potassium levels [ 10 ]. The patient had tacky mucous membranes, which suggested dehydration [ 10 ]. Otherwise, the patient was normotensive, bright, alert and responsive.
Pain relief should be prioritised, using appropriate analgesia [ 6 ]. This patient was in severe pain, so methadone( Comfortan, Dechra) 0.3 mg / kg was promptly administered by the intramuscular route.
Blood gas analysis and chemistry
An IV catheter was placed and blood taken for blood gas analysis and biochemistry. Biochemistry test results( Table 1, page 52) revealed azotaemia, due to an acute kidney injury. Urea and creatinine, both of which are excreted by the kidneys [ 11 ], were elevated. Specific nursing care for acute kidney injury includes intravenous fluid therapy( IVFT), monitoring urine production, appropriate nutrition, and administration of analgesia and antiemetics [ 10 ].
Blood gas analysis revealed a metabolic acidosis, which can reduce renal and hepatic blood flow [ 9 ]. Management included matching the IVFT to the urine output, and monitoring blood gases every 12 hours.
The blood results also identified marked hyperkalaemia, which occurs due to post-renal obstruction [ 12 ]. Hyperkalaemia can cause arrhythmias and asystole. It is therefore important to attempt to correct hyperkalaemia prior to sedation of the patient [ 13 ].
The patient needed to be stabilised as a priority. Calcium gluconate lowers serum potassium immediately, so it is usually the medication of choice [ 14 ]. For this patient, 0.5 ml / kg calcium gluconate( Fresenius Kabi), diluted 1:4 in saline, was administered IV over 10 minutes. An ECG monitoring the patient during administration showed tented T waves, which are found in patients with potassium levels above 7 mmol / l [ 1 ]. If bradycardia and QT interval shortening are seen on the ECG, the calcium gluconate should be stopped [ 13 ].
Dextrose helps to reduce potassium for a longer period than calcium gluconate [ 13 ]. This patient ' s calcium gluconate infusion was therefore followed by 0.5 ml / kg dextrose 50 %( Vétoquinol), diluted 1:4 in saline, administered IV over 5 minutes.
The patient ' s potassium level was lowered by these treatments but did not return to normal prior to the procedure to unblock the urethra. Acute kidney injury does not resolve until after a urinary obstruction has been relieved and supportive care has been provided through IVFT [ 10 ]. Therefore, it was important to continue the IVFT and to monitor the ECG throughout the procedure and until the urinary obstruction was resolved.
Volume 40( 6) • December 2025
51