Renal conditions and urinary tract infections

01 November 2009, at 12:00am

Benazepril and heparin in dogs with chronic kidney disease 

Jorg Tenhundfeld and others, University of Veterinary Medicine, Hannover, Germany 

Systemic hypertension is common in dogs with chronic kidney disease and may accelerate the loss of renal function. Hypertension can be effectively treated with ACE inhibitors such as benazepril hydrochloride. Another common feature of CKD is an activation of the coagulation system and thrombosis may be prevented by administering an anticoagulant, such as heparin. 

The authors examine the effects of benazepril alone and in combination with heparin on renal function and blood pressure in dogs with CKD. Treated dogs received 0.5mg/kg with or without 150 U/kg heparin for the first six days of ACEi treatment. Dogs in both treated groups had a significantly better health status by day 180 than the placebo group. 

These results confirmed that benazepril has beneficial effects in dogs with kidney disease but short-term treatment with heparin provided no additional benefits. 

Journal of the American Veterinary Medical Association 234 (8): 1,031-1,037. 

Diagnostic value of bacterial culture in detecting urinary tract infections in dogs 

Musavenga Tivapasi and others, University of California, Davis 

Urinary tract infections may be difficult to identify in dogs with dilute urine as it may not be possible to observe sediment abnormalities. Bacterial culture will be routinely carried out on such samples in some laboratories but the value of this procedure is unclear. The authors retrospectively evaluated the frequency of positive bacterial cultures in 1264 urine specimens. Their findings suggest that bacterial culture is not cost-effective in dogs with urine specific gravity below 1.013 in the absence of other indications of infection. 

Veterinary Clinical Pathology 38 (3): 337- 342. 

Desmopressin or water deprivation in testing for the cause of canine polyuria/polydipsia 

Marjorie Chandler, University of Edinburgh 

There are many potential causes of polyuria and polydipsia in dogs. One common diagnostic method used in these cases is the water deprivation test to differentiate between central diabetes insipidus and psychogenic polydipsia. However, the author believes that water deprivation is potentially dangerous in patients with an abnormal glomerular filtration rate and argues for the greater safety of a desmopressin test. But even this method should be used with caution in certain patients such as geriatric animals, she states. 

Veterinary Medicine 104 (6): 284. 

Pentosan polysulphate in cats with idiopathic, lower urinary tract disease 

Barbro Wallius and Anna Tidholm, Alban Animal Hospital, Danderyd, Sweden 

Treatment with glycosaminoglycans, such as pentosan polysulphate, is one of various options used in cases of idiopathic feline lower urinary tract disease but there is little evidence from rigorously conducted trials to confirm its value. The authors describe a study in 18 cats with this condition, comparing the effects of pentosan polysulphate and placebo. There were no statistically significant differences in clinical signs at up to 12 months followup. However, it is suggested that treatment might be beneficial in a subpopulation of affected cats. 

Journal of Feline Medicine and Surgery 11 (6): 409-412. 

White spot lesions as an indicator of leptospirosis in sheep at slaughter 

Sithar Dorjee and others, Massey University, New Zealand 

Focal interstitial nephritis in sheep presents as small grey-white lesions on the cortical surface of the kidney. White spotted kidneys are frequently observed in sheep with natural or experimental leptospirosis although it is not clear whether this is pathognomic. The authors conducted serum agglutination tests on blood samples from sheep at slaughter with visible lesions. They found that white spotted kidneys were a poor predictor for the antibody and pathogen status of sheep carcases in respect to leptospirosis. 

New Zealand Veterinary Journal 57 (1): 28- 33. 

Diagnosis and treatment of urolithiasis in horses 

Alicia Foley and others, Kansas State University 

Given the alkalinity of equine urine and its high calcium content, it might be expected that horses would be vulnerable to developing uroliths but their prevalence in this species is low. However, stones do occur occasionally, usually in the bladder rather than kidneys. The authors review the factors thought to be involved in the aetiology of such cases. They note that the condition can be readily diagnosed through rectal palpation, ultrasonography or endoscopy, while laser or shock wave therapies will usually produce better outcomes than surgery. 

Compendium Equine: Continuing Education for Veterinarians 4 (3): 125-133. 

Estimating glomerular filtration rate in dogs 

Benjamin Nolan and others, Tufts University, Massachusetts 

Glomerular filtration is a more sensitive and accurate indicator of renal function than determining blood urea nitrogen (BUN) or serum creatinine levels. It is usually assessed by measuring urinary clearance following inulin administration. The authors describe an alternative method involving gadolinium diethylenetriamine pentaacetic acid. Measurements of this compound using an ELISA method produced comparable results to those achieved using HPLC-based measurements of iohexol or inulin clearance. 

American Journal of Veterinary Research 70 (4): 547-552. 

Comparison of laser lithotripsy and cystotomy in managing canine urolithiasis 

John Bevan and others, University of Minnesota 

Cystotomy is still the most widely used method for removing uroliths from the bladders of canine patients but less invasive methods have become more popular in human medicine. The authors compare the efficacy and postoperative complication rates of cystotomy and laser lithotripsy in a total of 66 dogs with urolithiasis. The duration of hospitalisation was significantly shorter in dogs undergoing laser lithotripsy. But the procedure time and anaesthetic costs were lower with cystotomy, while the complication rate was comparable. 

Journal of the American Veterinary Medical Association 234 (10): 1,286-1,294. 

Urinary cortisol/cortisone ratios in hypertensive and normotensive cats 

David Walker and others, Royal Veterinary College, London 

Hypertension is a common problem in older cats, usually seen in association with chronic kidney disease. It has been suggested that reduced conversion of cortisol to cortisone contributes to the development of this condition in some cats with CKD. The authors compared urinary cortisol to cortisone ratios in 60 diseased and healthy cats and found that the cortisol to cortisone shuttle is actually more effective in cats with CKD than in healthy animals. The mechanism for this potentially adaptive response to kidney disease is not clear. 

Journal of Feline Medicine and Surgery 11 (6): 442-448. 

Protocol for conducting diuretic renal scintigraphy in normal cats 

Silke Hecht and others, University of Tennessee 

Diuretic renal scintigraphy is a non-invasive method for assessing renal function in which a diuretic is used to facilitate clearance of a radiopharmaceutical from a dilated urinary tract. The authors applied this technique to investigate renal function in cats,aspecies with a high incidence of urolithiasis and ureteral obstruction. Excretion of the radionuclide TcDTPA was significantly faster in healthy cats receiving frusemide than controls. The results suggest that this technique may be of value in investigating obstructive uropathies in cats. 

Veterinary Radiology and Ultrasound 49 (6): 589-564. 

Increased renal vascular resistance in dogs with hepatic disease 

Rosa Novellas and others, Autonomous University of Barcelona, Spain 

Doppler ultrasound is a non-invasive method for assessing renal haemodynamics, and can be used to estimate vascular resistance through calculations of the resistive index (RI) and pulsatility index (PI). Those two indices are known to be elevated in human patients with liver diseases and so are measured to monitor disease progression. The authors investigate whether this method can identify dogs with hepatic disease. In 20 affected dogs, the mean renal RI, PI and systolic blood pressure were all significantly higher than in healthy animals. 

The Veterinary Journal 178 (2): 257-262.