Any cat lovers out there are probably aware that urinary problems are common in cats. Whether it’s straining, spraying, or blood in the urine, your first port of call for urinary issues should be your local vet. Perhaps because they are common in humans, many owners wonder if their cat could have a urinary tract infection (UTI). While UTIs in cats are certainly not impossible, how often do they really occur? 

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FLUTD

Feline lower urinary tract disease (FLUTD) describes any disease affecting the bladder or urethra of a cat. Common causes of FLUTD include non-infectious cystitis (bladder inflammation), UTIs, bladder crystals or stones, polyps (benign masses) and certain cancers. Many cats also have idiopathic FLUTD (iFLUTD), where an obvious cause of urinary disease cannot be identified – stress is often a big factor.

The diseases causing FLUTD often have similar symptoms, making distinguishing them without testing difficult. FLUTD often causes: difficulties urinating; painful urination; urination in abnormal places; more or less frequent urination; blood in the urine; stress-signs like overgrooming and aggression; a hunched over appearance; difficulties walking; and systemic disease. In certain cases, FLUTD can result in bladder blockage, a serious emergency situation that can lead to bladder rupture, kidney damage and death if untreated. The biggest warning sign is a cat painfully straining but not producing any urine. 

It is commonly reported that around 1-3% of cats have FLUTD, with the majority being iFLUTD. Middle-aged cats, non-neutered cats, male cats and overweight cats are more likely to have urinary issues. It is also often reported that female cats are more likely to get UTIs.

When Is It a UTI?

In the past, it was generally assumed that UTIs in cats were rare. And certainly, older studies have shown this, reporting that of cats with FLUTD, 3% or less had UTIs. However, more recent studies have shown that UTIs may be more common than previously thought. One study from 2022 showed that of 2712 feline urine samples collected in the UK, 425 (15.7%) showed evidence of bacteria in the urine (bacteriuria). Other studies agree. A study in Indonesia identified 47 of 185 cats (25.3%) with bacteriuria, in Germany 57 of 302 cats (18.9%), and in Norway 33 of 134 cats (25%) showing bacteriuria. 

Though the studies seem to indicate that the number of cats with UTIs are likely to be higher than previously thought, they do point out problems with their results, particularly the larger British study – they note that sampling will not be representative of the general cat population, and many of the urine samples did not have information about the status of the cat, in particular whether they had already had antibiotics affecting the results. They also note that the presence of bacteria does not necessarily indicate treatment is necessary, and the cat’s symptoms should be taken into account too. The other studies are limited by small sample size. 

Other Findings

It is commonly believed that older cats are more likely to get UTIs, often because they have other underlying diseases. The German study showed there were significant differences between the ages of cats with FLUTD that had UTIs; 12.9% of cats under 10 versus 41.8% of cats over 10. The Indonesian study agrees, while the Norwegian study did not find a significant difference; the British study could not give results regarding age.

The British study went further than the other studies by analysing what sort of bacteria were present 

The most common was E. coli, followed by other Enterobacteriaceae (bacteria in the same family), Enterococcus spp. and Staphylococcus spp.. The numbers reported were similar to other older studies. More interestingly, they found that only 16.7% and 20.7% of E. coli bacteria were resistant to the common antibiotics amoxicillin and cephalexin respectively. This was lower than a previous study from Norway (64% and 60%). The similar Enterobacterales, however, were highly resistant to certain penicillin antibiotics. Enterococcus were highly resistant to trimethoprim-sulfamethoxazole (TMPS) (94.3%) and tetracycline (60%). Staphylococcus were also rarely resistant to amoxicillin (20%). 

These results indicate that since resistance varies between different antibiotics and different bacteria, testing the susceptibility of bacteria before treatment is important. Much of this resistance will be due to overuse of antibiotics in veterinary medicine, and certainly treating urinary tract infections without culture and sensitivity testing will be a factor too. It was positive to see that the most common cause of UTIs in cats, E. coli, is still highly susceptible to most antibiotics. 

Urine collection method might make a difference

Urine from cats can be collected via catching it as the cat urinates normally (free-catch), from a catheter, or via cystocentesis where a needle and syringe are used to take urine directly from the bladder. It is commonly argued that since cystocentesis is performed by a vet under sterile conditions, it is the most representative sample from the bladder, and that catheterisation or free-catch may result in bacterial contamination that could falsely show bacteriuria (a false positive result). The studies all used differing methods for collecting their urine. 

However, the Norwegian study found no significant difference between sampling method; indicating that the choice of sampling may not be that important. They did note that their analysis was performed quickly in ideal situations, so may not be reflective of general vet practice. It thus seems that cystocentesis is still likely to be the best method to assure an accurate urine sample, but other methods can still yield accurate results when performed correctly, if cystocentesis is not possible. 

What is the Lesson to Be Learned

The biggest lesson to be learned from these studies is that urinary tract infections in cats are more common than we think. While they are still rare compared to iFLUTD or cystitis, the numbers are high enough we should not discount them, especially in some cats (females, and possibly older cats in particular). 

It is impossible to know if a UTI is present without testing

Treating a cat without this information could lead to misdiagnosis, over- or underuse of antibiotics, the creation of resistance or lack of effective treatment, depending what treatments are selected before testing. Thus, all cats with FLUTD should have a urine test (other tests may be recommended to rule out other causes of FLUTD, such as blood tests or ultrasonography).

Urine should ideally be collected via sterile cystocentesis and analysed promptly to ensure the most accurate results. However, for cats that are very nervous or aggressive, or cannot be safely sedated, free-catch or catheterisation are acceptable provided the sample is taken carefully. 

Simply identifying bacteria is not sufficient for proper treatment

The treatment will be dependent on the bacteria present, certain antibiotics may or may not be effective. This means culturing the bacteria for sensitivity testing is essential (again, meaning cystocentesis is ideal). Since previous antibiotic use can affect these results, this should be done before starting any antibiotics. As always, treatment should be based on clinical signs, and a cat identified as bacteriuric with no clinical signs should not be treated with antibiotics. 

These guidelines are, of course, for ideal settings; for many owners, this level of testing may not be practical due to financial or patient reasons. In these situations, the use of broad-spectrum antibiotics may be appropriate once a UTI has been identified, as long as the owner is aware of the risks of not treating the infection and creating resistance. We would, however, strongly advise against the use of antibiotics for FLUTD with no evidence of a UTI.

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