Infections of the lower urinary tract: from diagnosis to treatment
Translated according to Patricia Dowling, DVM, MSC, Dacvim (Large Animal), DACVCP, Western College of Veterinary Medicine, Saskatoon, Saskatchewan, Canada
Bacterial urinary tract infections
Bacterial urinary tract infections are often diagnosed in dogs and cats. Although bacterial cystitis in dogs can occur in both sexes and in all age groups, it is observed older than 10 years, especially in castrated females and animals. The antimicrobial means used for treatment have not changed significantly, but concern about increasing antibiotic resistance increases. Careful and responsible handling of antimicrobial drugs is therefore essential. There are new recommendations for which types of bacteriuria should be treated, which antibiotics should be considered as first -line therapy and how long the treatment should take place.¹
diagnosis
The correct diagnosis of an infection requiring treatment comes first. In dogs and cats with clinical signs of urinary tract infection, a complete urine examination is indicated.
The indications for a urine culture and resistance test include:
- The anamnesis (e.g. sporadic or recurring infections)
- Clinical symptoms (e.g. painful urination, blood in urine, frequent urination, abnormal urine beam patterns)
- Visible detection of bacteria in the urine sediment
- Notes on Pyurie (pus in the urine)
Since urinary tract infections occur mainly in older cats - typically those with comorbidities - a urine culture and resistance test is already recommended when the initial diagnosis. However, reports from several veterinary clinics show that the correct diagnosis and the appropriate use of antibiotics in dogs and cats often do not match. In a recently carried out, unpublished study by the author, it was found that about 40 % of the diagnoses of a bacterial HWI in practice were not confirmed by a urine analysis in dogs and that urine cultures and resistance tests were not carried out in an accredited diagnostic animal laboratory.
Although the insufficient use of diagnostic laboratory services can be caused by factors such as costs and delays between sampling and the result, the administration of antibiotics on patients without infection requiring treatment is a serious misuse of these drugs.
Types of urinary tract infections
As soon as the diagnosis of urinary tract infection has been made, the exact type of infection should be determined before choosing an antimicrobial therapy plan.
Sporadic bacterial cystitis
Sporadic bacterial cystitis (SBC, also referred to as simple urinary tract infection) arises from a temporary break in the body's own defense mechanisms. Affected animals usually show typical symptoms of infection of the lower urinary tract and quickly address adequate therapy. Clinical symptoms do not occur afterwards or only rarely. Since most antibiotics in the urine achieve high concentrations, SBC is mostly one -off infections that respond well to adequate first -line therapy (see table).
If the infection diagnosis is correct, treatment in dogs can be empirically - based on the knowledge of the often isolated pathogens and their typical sensitivity to the antibiotics used. However Lower urinary tract disease is the Feline urological syndrome (formerly referred to as Feline idiopathic cystitis).
When choosing an antibiotic, the pharmacokinetics and pharmacodynamics of the active ingredient, possible side effects (both for the animal and the owner) should be taken into account, the simple handling of the administration and the costs.
The antibiotic concentrations achieved in urine are more important than the serum concentrations in the treatment of sporadic urinary tract infections. Usually the urine concentrations exceed the serum values because most antibiotics are excreted in an active form through the urine. If a concentration is achieved in the entire dosage interval, which is at least four times the minimal inhibition concentration (MIC), the effectiveness against the pathogen is secured with about 90 %.
be the first choice for initial infection with SBC by Escherichia Coli or Staphylococcus Pseudintermedius In contrast, initial or empirical treatment with amoxicillin/clavulanic acid is not recommended.
Since the symptoms of the SBC are usually caused by inflammation, the use of NSAID (non -steroidal anti -rheumatics) can also be considered - but with caution in cats. Antibiotic treatment should only be started when the clinical symptoms stop or worsen. New recommendations provide for antimicrobial therapy to be used for only 3 to 5 days, although longer treatment duration are often specified on the package insert. If the symptoms dissolve after short -term treatment, further urine examinations or cultures are not necessary.
Antimicrobial treatment options for urinary tract infections
The following options are listed in the order of their preference in accordance with the principles of a responsible antibiotic use.
First choice
- Amoxicillin
dosage: 11–15 mg/kg, oral, every 8–12 hours
recommended first selection therapy for SBC. A gift every 8 hours can improve the effectiveness. Ampicillin should be avoided because of its low bioavailability. Not suitable for prostatitis or pyelonephritis due to a lack of tissue perfusion. - Sulfadiazin/Trimethoprim
Dosage: 15–30 mg/kg, orally, suitable every 12 hours
as an initial selection therapy for SBC, but is less often used in clinically due to possible side effects in dogs and bad taste in cats. Can be considered in prostate infections. However, enterococci are naturally resistant. - Cephalexin and Cefadroxil
dosage: 12–25 mg/kg, oral,
first generation Cephalosporins; Potential first selection option at SBC if amoxicillin is not suitable. Enterococci are of course resistant. Due to the low tissue penetration, not recommended for prostatitis or pyelonephritis. - Nitrofurantoin
dosage: 5 mg/kg, orally, every 6–8 hours
can be considered as an initial election option at SBC if amoxicillin is not suitable and multidrug-resistant pathogens are available. Cannot be used in prostatitis or pyelonephritis, since no therapeutic concentrations are achieved in the tissues.
Second election
- Amoxicillin/Clavulanic acid
dosage: 12.5–25 mg/kg, orally,
no proven advantage over amoxicillin at SBC every 12 hours, unless susceptibility data demonstrate a high level of resistance to amoxicillin, but sensitivity to the combination. Here too, tissue penetration in prostatitis or pyelonephritis is insufficient. - Cefpodoxim
Dosage: 5–10 mg/kg, oral, every 24 hours (for dogs)
a third generation cephalosporin, reserved in cases with documented resistance to the first generation. Enterococci are inherently resistant. - Cefovecin
dosage: 8 mg/kg, subcutaneous, unique; Repetition possible after 7–14 days
also a third generation cephalosporin, intended for documented resistance to the first -line medication. Enterococci show natural resistance.
Third choice
- Enrofloxacin
Dosage:- Dogs: 5–20 mg/kg, oral, every 24 hours
- Cats: 5 mg/kg, orally, reserved for multidrug-resistant pathogens every 24 hours
, but can be used as a first election in prostatitis and pyelonephritis. In cats, the application is restricted due to the risk of retinopathy.
- Marbofloxacin
dosage: 2.75–5.5 mg/kg, orally,
reserved every 24 hours for multidrug-resistant pathogens and uropathogenic E. coli (UPEC), but can also be considered as first election in prostatitis and pyelonephritis. - OrbiFloxacin
dosage: 2.5–7.5 mg/kg, oral, every 24 hours
similar to marbofloxacin-reserved for multidrug-resistant pathogens and UPEC, but possible as a first election in prostatitis and pyelonephritis. - Pradofloxacin
Dosage:- Dogs: 3–5 mg/kg, oral, every 12 hours
- Cats: 3–7.5 mg/kg, orally,
reserved every 24 hours for multidrug-resistant pathogens and UPEC, can also be considered in prostatitis and pyelonephritis as a first selection. Pradofloxacin shows a higher activity against some bacteria than enrofloxacin, marbofloxacin and orbibloxacin. Not approved for dogs in the United States, but is available in other countries. In addition, it does not cause retinopathy in cats.
- Chloramphenicol
Dosage:- Dogs: 40–50 mg/kg, oral, every 8 hours
- Cats: 50 mg per cat, orally,
reserved every 12 hours for multidrug-resistant pathogens and UPEC. Can be considered in pyelonephritis or prostatitis if fluorchinolone is not an option. However, due to the risk of myelosuppression (especially in cats) and a potential risk of an idiosyncratic, dose -independent aplastic anemia in humans, chloramphenicol should be used with caution.
- Doxycycline
dosage: 5 mg/kg, oral, reserved every 12 hours
for methicillin-resistant staphylococci and UPEC. Can be considered as an alternative in pyelonephritis or prostatitis if fluorchinolone are not suitable. There is special caution in cats, since tablets or capsules can be a risk of esophageal ulcerations. It is recommended to administer each tablet or capsule with about 6 ml of water using syringe. - Fosfomycin
dosage: 40 mg/kg, oral, every 8–12 hours (for dogs)
reserved for multidrug-resistant pathogens. Can be used every 8 hours in pyelonephritis or prostatitis if fluorchinolone does not display an option.
Recurrent bacterial cystitis
Recurring bacterial cystitis arises from a persistent underlying disturbance in the urinary tract or the immune defense, which leads to at least three episodes of urinary tract infections in the previous 12 months or at least two episodes in the past 6 months. That can vary and is not always Effectively treatable, so that long -term, repeated antibiotic therapy usually promises little success.
- Reinfection occurs when after successful therapy (documented by a negative urine culture) a new infection occurs with another bacterial species or another trunk. In such cases, extended diagnostic measures should be taken into account in order to identify treatable predispositions. The treatment then takes place as with sporadic cystitis - long -term antibiotic therapy is not recommended.
- Relapse exists if the original infection has not been fully eliminated despite the therapy. Relapses can occur secondarily to pathological conditions such as biofilm formation, urolithiasis or pyelonephritis that prevent an adequate concentration of the antibiotic at the point of infection. Escherichia coli is the most frequently isolated pathogen that causes urinary tract infections in dogs and cats.
relapses in an E. coli infection can occur, which enable the pathogen to penetrate the urin epithelium, multiply there and to avoid high urine concentrations of antibiotics . Especially when the resistance pattern remains constant-an uropathogenic E. coli (UPEC) infection is considered. With recurrent urinary tract infections, it is important to ensure that sufficient antibiotic concentrations are achieved in the urine and in the bladder to eliminate the infection. The choice of antibiotic, the dosage scheme, the resistance pattern and the compliance of the pet owner should be checked, since only a few medication treats intracellular infections or biofilm infections effectively.¹ In addition, a high proportion of antibiotic resistance was documented in dogs with UPEC.¹
graph
The diagram : Pathogenesis of UPEC infections:
The urinary bladder UROEPITHEL is a pseudostratified transition epithelium that is lined by large surface cells (facet cells) (a). UPEC that reach the bladder attachment via Pili on the surface of the Facet cells (B). After adherence, UPEC penetrate (C) and replicate (D).
They then form intracellular bacterial communities (E) that are protected from antibiotics because they do not penetrate the cells in sufficient concentration. The host's immune response recruits neutrophil granulocytes, and infected cells can be repelled and excreted by the urine, which contaminates the environment and transferred the infection to new hosts (f). Alternatively, bacteria from the intracellular community can develop a filamentous morphology and attach again to other facet cells in bladder lumen (G), which means that the infection cycle begins.
Subclinical bacteriuria
Subclinical bacteriuria is not unusual for otherwise healthy animals, in patients with comorbidities (e.g. diabetes mellitus, chronic kidney disease) or those that are treated immunosuppressive. Despite the fear that secondary complications such as sepsis or pyelonephritis could occur, there is only a few indications that subclinical bacteriuria increases the risk of clinical urinary tract infections or other infectious complications in dogs or cats.¹
In human medicine, a subclinical bacteriuria is usually not treated, not even with immunocompromised patients. Treatment can lead to the elimination of the bacteriuria at short notice, but a new settlement is common and associated with increasing antibiotic resistance. Therefore, it is now recommended if bacteria are detected in the urine, but there are no clinical signs of urinary tract infection, no urine culture or susceptibility test and not to treat the animal with antibiotics. Even the detection of a multi -resistant pathogen does not necessarily justify treatment.
The clinical decision as to whether a patient should be treated without symptoms (for example due to a spinal cord injury or immunosuppressive treatment) must be made individually.
Treatment
First line therapy for patients with sporadic bacterial cystitis is the administration of amoxicillin over a period of 3 to 5 days.¹ If the clinical symptoms no longer occur after short -term therapy, no further diagnostic measures or treatments are required. In the case of reinfections, as with SBC, special attention is paid to the identification of underlying abnormalities. Relapses can occur due to complex pathologies in which UPEC and biofilms require special therapeutic considerations. Patients with subclinical bacteriuria should not be routinely treated with antimicrobial means even if commentary diseases exist.
Common questions about infection of the lower urinary tract
What are urinary tract infections and what symptoms can occur in dogs and cats?
Urinary tract infections (HWI) affect the lower urinary tract, especially the urinary bladder and the urethra. Dogs and cats are mostly bacterial infections, which through the penetration of pathogens - often Escherichia coli or staphylococcus SPP. - arise in the urinary tract. The typical symptoms include:
Painful urination (dysuria): Affected animals often show signs of discomfort or pain when urinating.
Frequent urination (pollakiuria): It can lead to increased but frequent urination in small quantities.
Blood in urine (hematuria): Visible blood or a reddish color stitch in the urine is a common symptom.
Changed urine beam patterns: Some animals show a weak or interrupted urine beam, which can indicate a changed anatomy or inflammation.
General discomfort: fever, reduced activity or loss of appetite can also be signs of infection, especially if the infection has extended to the kidneys (pyelonephritis).
HWI appear more often in older cats, especially neutered females. Early detection and treatment is important to avoid complications and to maintain the quality of life of the animal.
How is the diagnosis of urinary tract infection made?
A urinary tract infection is diagnosed by a systematic and multi -stage approach, which ensures that the correct treatment takes place. The most important diagnostic steps include:
anamnesis and clinical examination: The veterinarian first raises a detailed medical history and observes the behavior of the animal. Symptoms such as painful urination, frequent urination or blood in the urine are noted.
Urine analysis: A complete urine analysis is essential. Parameters such as pH value, density, the presence of white blood cells (pyuria), red blood cells and bacteria are examined. This investigation provides initial indications of an infection.
Urine culture and antibiotic sensitivity test: Especially in recurring infections or in cases in which the risk of antibiotic resistance exists, an urine culture is made. The bacteria are isolated and their sensitivity to various antibiotics are tested. These tests help to determine the best possible therapy and to ensure the targeted use of medication.
Other imaging methods: In some cases, especially if anatomical anomalies or structural changes are suspected, additional imaging methods such as ultrasound or X -rays can be used.
These careful diagnostic steps ensure that not only a urinary tract infection is determined, but also recognized the exact type and possible causes. In this way, targeted and effective therapy can be initiated.
What types of urinary tract infections are there and how do they differ?
Urinary tract infections can be divided into different categories, whereby the distinction helps especially with the choice of treatment. The most important species are:
sporadic bacterial cystitis (SBC):
This is the most common form and arises from a temporary breakdown of the body's defense mechanisms. The symptoms suddenly occur and usually sound after a short, usually 3 to 5-day antibiotic therapy. Another infection is rare if there are no underlying causes.
Recurring bacterial cystitis:
With this form, at least three infections occur within 12 months or two within 6 months. Often there is a persistent disorder of urinary tract or insufficient immune defense. Either new pathogens (reinfection) or the recurring of the same pathogen (relapse) can be the cause.
Subclinical bacteriuria:
This is the detection of bacteria in urine without the presence of clinical symptoms. This is not unusual in older animals or those with chronic diseases such as diabetes or kidney diseases. As a rule, this form is not treated because it is not associated with an increased risk of serious complications and treatment can often lead to resistant bacteria.
The distinction between these forms is important because it directly influences the treatment strategy and the use of antibiotics. While sporadic infection usually responds well to a short therapy, recurrent infections often require further diagnosis for the identification of precursor diseases.
What are the treatment options and how is the choice of antibiotic made?
The treatment of urinary tract infections is primarily based on the type and severity of the infection and the results of the antibiotic sensitivity tests. Here are some important points for treatment:
first -line therapy for sporadic cystitis:
For most uncomplicated cases, amoxicillin is recommended over a period of 3 to 5 days. This therapy is based on the fact that amoxicillin is excreted in high concentrations in the urine, which means that an effective effect can still be achieved with a possible resistance pattern in laboratory test.
Selection of the antibiotic:
In addition to pure effectiveness, pharmacokinetics (how the drug is distributed and excreted in the body) and pharmacodynamics (how the drug works) plays an important role. Possible side effects, simple administration and costs are also taken into account. There are various options, from cephalosporins to fluorchinolons, which are considered in complicated cases such as prostatitis or pyelonephritis.
Treatment of recurrent infections:
In recurring infections, it is important to identify and treat the underlying causes. Long -term, repeated antibiotic agency is usually not recommended because it can lead to an increased risk of resistance.
Non -antibiotic approaches:
In the case of slight inflammation, non -steroidal anti -inflammatory drugs (NSAID) can also be used to reduce the inflammatory reaction. Supportable measures, such as an increase in water absorption, can also be helpful to wash out the bacteria.
The combination of precise diagnostics and the selection of a suitable, often empirically used antibiotic ensure that therapy is targeted and unnecessary use of medication is avoided.
How can you prevent renewed urinary tract infection and what should be considered in long -term treatment?
The prevention of urinary tract infections and the handling of recurrent cases are an important part of veterinary care. Here are some approaches to prevent and long -term care:
Identification and treatment of underlying causes:
Often there are anatomical or functional disorders of urinary tract, such as urinary stones or structural anomalies, before that favor repeated infections. Comprehensive diagnostics, often supplemented by imaging methods such as ultrasound, can help to recognize such causes and to treat them in a targeted manner.
Optimization of hygiene measures:
regular and careful hygiene, especially in cats, can reduce the risk of renewed infection. This also includes cleaning the cat toilet and ensuring that the animal has access to fresh water at any time.
Adapted nutrition and lifestyle:
A balanced diet that contributes to general health and function of urinary tract is important. In certain animal species or breeds, the addition of cranberry products or other natural preparations can be supportive, although the scientific evidence varies for this.
Avoiding unnecessary antibiotic therapy:
Responsible handling of antibiotics (antibiotic stewardship) is crucial to avoid resistance. In the case of subclinical bacteriuria in particular, treatment should be dispensed with, since it often leads to a new settlement and resistance.
Regular checks:
Regular checks (urine analyzes and cultures) are useful for animals that have already suffered repeatedly urinary tract infections in order to react early to changes and to monitor the course.
A combination of preventive measures, targeted therapy and regular control can significantly reduce the risk of renewed urinary tract infections, so that the animal's quality of life is sustainably improved.
Conclusion
Your urinary trouble problem is an important topic for many pet owners. Infections of the lower urinary tract are a common problem. Many dogs and cats suffer from infections of the lower urinary tract . Treatment of the lower urinary tract infections can make the treatment much easier. Even if infections of the lower urinary tract are often uncomplicated, an exact examination is necessary.
The causes of infections of the lower urinary tract are diverse and range from bacterial pathogens to structural anomalies. A common cause of infections of the lower urinary tract is the bacterial settlement by Escherichia coli . Hormone disorders can also contribute infections of the lower urinary tract Veterinarians emphasize that infections of the lower urinary tract are often favored by inadequate hygiene or accompanying diseases. An early detection of infections of the lower urinary tract is essential to avoid complications.
The diagnosis of infections of the lower urinary tract is through a combination of clinical examination and laboratory analyzes. A urine analysis provides information on infections of the lower urinary tract and supports the decision for further diagnostics. Cultural investigations confirm infections from the lower urinary tract and help choose the right antibiotic. Modern techniques make it possible to precisely identify infections of the lower urinary tract Knowledge of infections of the lower urinary tract significantly improves the success of the treatment. Long -term studies show that infections of the lower urinary tract can be checked faster in the event of early intervention.
The treatment of infections of the lower urinary tract depends on the type and severity of the disease. In many cases, infections of the lower urinary tract treated with short -term antibiotic therapy. Recurring infections of the lower urinary tract often require a detailed examination of the underlying causes. Veterinary doctors recommend taking preventive measures infections of the lower urinary tract An adapted diet can help infections from the lower urinary tract . Regular checks minimize the risk of infections of the lower urinary tract . With the right care, infections of the lower urinary tract often be successfully avoided.
In summary, it is important to recognize infections of the lower urinary tract Preventive measures can often avoid infections of the lower urinary tract A timely diagnosis ensures that infections of the lower urinary tract are treated quickly. Advanced diagnostic methods make it possible to precisely identify infections of the lower urinary tract
The selection of the right antibiotic is crucial to effectively combat infections of the lower urinary tract Veterinarians should always make sure that infections of the lower urinary tract do not become recurring problems. Regular examinations can be recognized at an early stage Good communication between the vet and owner helps to optimally manage infections of the lower urinary tract In the long term, the goal is to completely avoid infections of the lower urinary tract With the right management, infections of the lower urinary tract significantly improve the quality of life of the animals.
Note: This article was originally published in February 2022 under the title "Lower Urinary Tract Infections".
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