Cat Urinary Infections: An Overview

Dog Breeds

Urinary tract infections, or UTIs, in people are most commonly associated with bacterial infections. However in cats, urinary tract infections are only caused by a bacterial infection in less than 10% of all diagnosed cases.

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Definition

A urinary tract infection (UTI) is a bacterial, fungal or algal infection anywhere along the urinary tract, which includes the kidneys and ureters (the upper urinary tract), and the bladder and urethra (the lower urinary tract).

How Urinary Tract Infections Affect Cats

Urinary tract infections in dogs (and in people) are most commonly associated with bacterial ascension from the outer environment up the urethra and into the bladder. In cats, UTIs are caused by simple bacterial ascension in less than 10% of all diagnosed cases. Perhaps the most frequent feline urinary tract disorder is a condition called feline idiopathic lower urinary tract disease (FLUTD), also called feline urological syndrome (FUS), lower urinary tract signs or idiopathic cystitis. This is not a “disease” per se but rather refers to a group of clinical signs which typically include hematuria, dysuria, pollakiuria and partial or complete urethral obstruction by uroliths (“stones”), calculi or crystals (more fully defined below). Please see the PetWave article on FLUTD for more information about this particular feline disorder, which tends not to be caused by bacterial infection.

Urinary tract infections are less common in cats than in dogs and are more common in females in both species. Frequently, they are unaccompanied by clinical signs, although they tend to be quite painful. When cats do show observable clinical signs of a UTI, they tend to include abnormally frequent attempts to urinate producing only small volumes of urine (pollakiuria), straining to urinate or excessive urgency (stranguria), difficulty urinating (dysuria), inappropriate urination in places that are not customary (outside the litterbox), malodorous urine, noticeable blood in the urine (hematuria), cloudy urine and possibly inflammation and irritation around the cat’s external genitalia. Cats also may become incontinent, feverish, lethargic, listless, depressed and/or anorexic.

Causes of Feline Urinary Tract Infections

Urinary tract infections are not common in cats. When they do occur, most feline UTIs develop as a result of some underlying medical condition or anatomical defect that predisposes the cat to infection by bacteria, viruses or fungi. Simple bacterial ascension with no predisposing condition is very uncommon. Feline leukemia virus, feline immunodeficiency virus, bladder tumors or polyps, bladder or kidney stones (uroliths), pyelonephritis, urinary retention disorders, kidney dysfunction or failure, strictures and congenital urachal remnants, other congenital deformities of the urinary tract, cancer, long-term immunosuppressive corticosteroid therapy and hyperadrenocorticism can predispose cats to repeated UTIs, even with aggressive antibiotic treatment. Elevated urine pH from any cause can facilitate bacterial overgrowth in the bladder. Diabetes mellitus is also associated with persistent or recurrent UTIs, because elevated blood and urine glucose levels create a supportive environment for bacterial overgrowth. Finally, an emerging and unfortunate cause of recurrent feline (and canine) urinary tract infections is bacterial resistance to antimicrobial drugs.

Some cats have recurrent UTIs that are termed “idiopathic,” which means that the cause of the infection is unknown. While still under investigation, it has been suggested that some types of immune-mediated hypersensitivity (allergies) can cause bladder irritation and inflammation, which may contribute to persistent urinary tract infections in cats. While uncommon, cats occasionally develop UTIs due to simple bacterial ascension into the urinary tract in the absence of predisposing conditions. Bacterial urinary tract infections are more common in females because they have a shorter urethra, and therefore bacteria have a shorter journey from the external genital environment to the bladder. Occasionally, other organisms are the culprit; these can include Chlamydia, mycoplasma, viruses and fungi. In addition to the pain and discomfort caused by these infections, the bacteria or other contributing organisms can proliferate and infect areas in addition to the lower urinary tract, particularly the ureters and kidneys. Even more serious is the potential for systemic infection, which is a life-threatening medical emergency.

Preventing Feline Urinary Tract Infections

Obviously, preventing or correcting any predisposing disorder is the best way to reduce the risk of UTIs in cats. When underlying predisposing medical or anatomical conditions cannot be controlled or eliminated, cats with bacterial UTIs may require long-term, low dose prophylactic antibiotic treatment, which carries its own risks. Another preventive measure is avoiding the indiscriminate use of urinary catheters. Free access to fresh water can promote hydration and help flush microorganisms out of the urinary tract. Regular urination is also important to prevent accumulation, reproduction and concentration of bacteria in the bladder.

Special Notes

Hard to prevent, difficult to detect and dangerous if untreated, urinary tract infections – although uncommon - can affect cats of all ages and breeds. Because so many UTIs are asymptomatic, it is especially important for cat owners to rely on veterinary protocols for accurate diagnoses. The prognosis for cats with uncomplicated bacterial urinary tract infections is excellent. Primary fungal infections, on the other hand, are extremely difficult to resolve. The prognosis for complicated UTIs caused by underlying predisposing conditions is quite variable.

Even asymptomatic UTIs, if left untreated, can lead to a number of much more serious conditions. We cannot overemphasize the importance of regular veterinary examinations, including blood tests and urinalyses, to identify and treat the UTIs that would otherwise go undiagnosed because the cats do not act unusual. Chronic, untreated UTIs can contribute to escalating damage to the lining and tissues of the urinary tract and elsewhere, which can be much more difficult to treat as time passes. Because UTIs are less prevalent in males, any UTI in a male cat should be considered serious.

Preventing Cat Urinary Infections