Abstract
Benign Paraganglioma: A Potential Cause of Hypertension in Cats
Linda M Fleeman1, Brett Stone2, Sandra Martig3, Anu O’Reilly4, Sue F Foster5
1Animal Diabetes Australia, Melbourne, Victoria, Australia
2Queensland Medical Laboratory (QML) Pathology, Vetnostics, Brisbane, Queensland, Australia
3Centre for Animal Referral and Emergency, Melbourne, Victoria, Australia
4Melbourne EyeVet, Melbourne, Victoria, Australia
5Vetnostics Laboratory, Sydney, New South Wales, Australia
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Improved understanding of non-azotaemic hypertension in cats is required because 13–20% of feline hypertension is idiopathic.
A16-year-old neutered male cat presented with chronic weight loss, polydipsia, increased activity, bilateral pinpoint multifocal grey retinal lesions and non-azotaemic hypertension. Hyperthyroidism, hyperaldosteronism, hyperadrenocorticism and adrenal/periadrenal tumour were excluded. CT revealed pulmonary overinflation and bronchiectasis, potentially due to excess catecholamines. Urinary catecholamines/metanephrines were compared with four control cats with similar signalment, including the littermate of the patient. Urine collected in a stress-free manner was immediately frozen at –20°C. Urine creatinine analysis via rate-blanking Jaffe reaction and catecholamine/metanephrine analyses via liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) were performed. Unpaired, one-tailed f-tests were used to compare results.
Urinary normetanephrine:creatinine ratios in the patient (median [range], 123 [93-228] nmol/mmol) were approximately three times higher than in the controls (43 [27–70] nmol/mmol) (P = 0.06). There were no differences for the other urinary catecholamines/metanephrines. Results were consistent with benign paraganglioma. Retinal lesions stabilised with 1.25 mg amlodipine PO q12h before diagnosis. After diagnosis, treatment first with 2.5 mg, and then 5.0 mg of phenoxybenzamine PO q12h arrested weight loss.
This is the first feline case to fulfil criteria for diagnosis of benign paraganglioma in humans. This potential cause of hypertension in cats could have been previously overlooked. Measurement of urinary metanephrines might be a practical screening test for this condition. Oral amlodipine and phenoxybenzamine provided effective long-term control of signs.
Feline Ureteral Obstruction: A Case-Control Study of Risk Factors (2016–2019)
Alex Kennedy, Joanna White
SASH, North Ryde, New South Wales, Australia
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Ureteral obstruction (UO) in cats causes acute kidney injury and typically requires surgical intervention. Further information is required about potentially modifiable risk factors to inform prevention strategies.
A case-control study was performed to assess risk factors associated with feline UO. Cases had: (1) UO confirmed with pyelography; or (2) a creatinine concentration >140 ug/ml and both UO and pyelectasia ≥5 mm identified ultrasonographically. Controls had no evidence of UO on history, physical examination and abdominal ultrasound. Age, sex, breed (domestic or pedigree), diet (predominantly dry, mixed or predominantly wet food), housing (indoors or mixed) and total calcium were evaluated for their association with UO using multivariable logistic regression. A receiver operating characteristic (ROC) curve was created to evaluate the final model.
One hundred and sixty-eight cats (28 cases, 140 controls) were included. Neither age (P = 0.46), sex (P = 0.78), total calcium (P = 0.42), breed (P = 0.89) nor housing (P = 0.83) were significantly associated with UO.
Diet was significantly associated with UO. Compared with cats eating a predominantly wet food diet, cats fed a predominantly dry food diet were 15.9 times more likely to develop a UO (confidence interval 2.9–295, P = 0.009). There was no difference in the association between diet and UO in cats fed a mixed or predominantly wet food diet (P = 0.25). The area under the ROC curve was 72%.
While the study is limited by owner recollection of diet, changes in dietary formulation could provide a simple and economical method of reducing the risk of UO.
