Feline lower urinary tract diseases are characterized by hematuria, pollakiuria, and dysuria, and are common problems encountered in feline practice. It is estimated that they affect over one half million cats in the United States annually. Although there are numerous recognized causes of these signs, the exact cause is never identified in the majority of cases.
Hyperthyroidism is one of the most commonly diagnosed diseases of the older cat. Geriatric cats with hyperthyroidism may also have concurrent chronic kidney disease (CKD). Systemic hypertension, proteinuria, and urinary tract infection (UTI) can be consequences of either hyperthyroidism or CKD.
Most bacterial infections of the lower urinary tract respond quickly to antimicrobial treatment; however, urinary tract infections (UTI) associated with defects in the host immune system (complicated UTI) often fail to respond or recur after antibiotic withdrawal and can be a therapeutic challenge.
Azotemia is defined as increased concentrations of urea and creatinine (and other nonproteinaceous nitrogenous substances) in the blood. The interpretation of serum urea nitrogen and creatinine concentrations as a measure of renal function requires a knowledge of the production and excretion of these substances.
By altering pre-glomerular resistance, healthy kidneys can maintain relatively stable glomerular capillary pressures despite variations in systemic blood pressure. This process is termed "renal autoregulation". Autoregulation can be reduced when renal disease results in loss of nephrons.
Over the last several years, there has been a shift in the mineral content of uroliths in cats from predominantly magnesium-ammonium phosphate (MAP) to calcium oxalate (CaOx). Of the nephroliths and ureteroliths analyzed by the Minnesota Urolith Center in 2002, 70% of 170 renolith submissions and 98% of ureterolith submissions were CaOx.
Persistent proteinuria of renal origin is an important marker of chronic kidney disease (CKD) in dogs and cats. Unfortunately, due to the high incidence of false-positive results for proteinuria on the urine dipstick screening test and proteinuria associated with lower urinary tract inflammation, positive reactions for urine protein are quite common and therefore often disregarded.