Sep 01 2011

How did my dog get a urinary tract infection?

by Dr. Lisa Yung

WHAT:

A lower urinary tract infection (LUTI) is when there is an infection in the lower urinary tract – i.e., the bladder. The medical term is “cystitis,” and when the infection is caused by bacteria, it is a “bacterial cystitis.” Nobody gets a viral bladder infection, and fungal bladder infections are possible but extremely rare.

LUTI is different from a kidney infection – kidney infections are very serious and the pet is systemically ill and may show bloodwork signs of kidney failure. If untreated, LUTI can progress “upwards” towards the kidneys and cause a kidney infection, so we attempt to treat as soon as possible to prevent a more serious disease from occurring as well as relieve the patient of discomfort.

SYMPTOMS:

Patients with bladder infections can exhibit:

  • Increased or abnormal urination – asking to be let out more, urinating in the house. Pet will usually just urinate small amounts
  • Painful urination – whining when urinating and the discomfort can be severe enough (bladder infections can hurt!) that the pet can be lethargic, acting “off,” and even decreased appetite.
  • Blood in the urine – urine can be pink tinged, red, or even a dark brown.
  • No symptoms at all and we find evidence of infection on a routine urine sample on a wellness visit

HOW:

Most LUTI’s are from ASCENDING infections – this means that bacteria from the outside travel up the urinary tract and seed the bladder with infection.

Because of this…

WHO:

Most uncomplicated (more on this later) LUTI’s occur in FEMALE dogs since the urethral opening is close to the anal opening and bacteria from feces can contaminate the vulva area. For this reason, male dogs do NOT tend to get uncomplicated LUTIs – the anal opening in male dogs is quite far away from the urinary tract opening AND the male urethra is long, so bacteria has to travel a long way to get to the bladder. This is why veterinarians are often much more aggressive when presented with a bladder infection in a male dog.

DIAGNOSTICS AND TREATMENT:

Uncomplicated  In uncomplicated cases, expect that the attending veterinarian will at the very least run a urinalysis sample. It may be requested that you bring in a free catch urine sample in a clean container, or if that is difficult, we ask that you keep the pet from urinating for an hour prior to your appointment so that we will have urine in the bladder to collect.

The veterinarian will prescribe an empirical antibiotic (meaning an antibiotic that historically tends to resolve most uncomplicated infections) and monitor for response. A recheck urine sample 3-5 days after the last antibiotic dose is recommended to ensure resolution of infection. In most cases, the veterinarian may recommend a urine culture with the urinalysis or order a urine culture as a recheck instead of a urinalysis. Urine cultures are “gold standard” for defining a urinary tract infection since a urinalysis can sometimes miss the bacteria infection. Urine cultures also ensure that the right antibiotic is used for the particular bacteria species.

Complicated   Complicated cases are those in which there may be more involved than “just” a bacterial infection. Examples are if the infections keep reoccurring, patients who are either on immunosuppressive therapy such as corticosteroids or are immunosuppressed from a condition like cancer, if bladder stones are detected, or there are other concurrent illnesses like Diabetes or Cushing’s or Kidney Failure. These cases require a urine culture right off the bat, as well as potentially bloodwork to check kidney values. Imaging diagnostics like a bladder ultrasound may be attempted to evaluate the bladder wall integrity.

PROGNOSIS:

Good to excellent with uncomplicated infections, good to fair in complicated infections.

LifeLearn Admin | Pet Health Blog