Subclinical bacteriuria — a hidden diagnosis for both dogs and veterinarians

Background

Urinary tract infections (UTIs) are relatively common in dogs and can cause problems and suffering for both the dog and the owner. In the past, urine was considered sterile, and a high bacterial count was usually interpreted as a sign of infection. Recent research shows that bacteria can be present without the dog showing any symptoms. This phenomenon is called subclinical bacteriuria. Since urinary tract infections in dogs are a problem often treated with antibiotics, it is of the utmost importance to increase knowledge about subclinical bacteriuria to ensure that antibiotics are not given to dogs that carry bacteria but show no signs of illness.

Project overview

There are significant gaps in our knowledge regarding subclinical bacteriuria. Only a few scientific studies have been conducted, and none of them have been carried out in Sweden.

In the planned study, we will begin with a screening using bacteriological analysis of spontaneously collected urine samples from dogs showing no signs of urinary tract infection. The urine will be analyzed for the presence of bacteria to determine (i) whether, and if so, to what extent, subclinical bacteriuria occurs in Swedish dogs, and (ii) whether the dog’s sex (female/male) plays a role. Dogs with suspected subclinical bacteriuria—i.e., bacterial growth in conventional cultures—will be specifically studied by collecting urine samples directly from the bladder on multiple occasions via cystocentesis in order to (iii) quantify the bacterial load and (iv) determine how long the dogs may remain carriers of bacteria in their urine. The bacteria detected will be identified to the species level using MALDI-TOF MS and stored at -70°C. The bacteria will undergo whole-genome sequencing and be compared with bacterial species detected in dogs with urinary tract infections.

Objectives

The aim of the project is to gain a better understanding of the prevalence of subclinical bacteriuria in dogs in Sweden and to determine whether dogs can be chronic carriers of bacteria in their urine or whether the bacteria are present only for a limited time.  In addition, we want to gain an understanding of which bacteria are most commonly found in subclinical bacteriuria; specifically, whether the bacterial species present in subclinical bacteriuria are the same as those found in dogs with urinary tract infections that exhibit signs of illness. One objective of studying the genome of bacteria detected in subclinical bacteriuria is to gain a better understanding of the possible presence or absence of virulence factors.