By Dr. Becker
Bacterial urinary tract infections (UTIs) are fairly common in dogs, and similar to humans, females are more often affected. E. coli bacteria is responsible for about half of all canine UTIs.
The development of a urinary tract infection is the result of a change in a dog’s immune defenses that allows pathogenic bacteria to proliferate. This can be the result of a disease process, the dog’s individual anatomy, the use of catheters, and certain drugs.
For example, dogs with diabetes or Cushing's disease (hyperadrenocorticism), dogs who are treated repeatedly with steroids (e.g., prednisone), and hospitalized dogs who are catheterized have more E. coli-related bacterial UTIs than other dogs.
Unfortunately, adding antibiotics to the mix can further increase the risk, as does the increasing age of the dog.
Risks Associated With Chronic Urinary Tract Infections
Urinary tract infections are treated with antibiotics. For treatment to be successful, it’s important that the appropriate drug is selected (which requires a culture and sensitivity test), and the length of therapy is adequate.
There are many side effects of antibiotic use, including gastrointestinal (GI) symptoms that can lead to the dog’s owner not giving the drug as prescribed, the dog refusing the drug, and/or decreased absorption leading to inadequate levels of antibiotic in the blood or urine.
These issues can interfere with the elimination of the bacteria that is causing the UTI, and can also contribute to antibiotic resistance. When a dog has recurring UTIs, it can be the result of a too-short course of antibiotic therapy, or the inability of the drug to reach the location of the bacteria.
Sometimes, relapses occur very quickly after a course of antibiotics is finished; other times, the infection reappears after some time has passed, in which case it can be mistaken for a new infection.
Antibiotic resistance is a growing problem in both human and veterinary medicine. A 2008 study revealed that bacterial resistance is highest in dogs with recurrent E. coli-related urinary tract infections.1
An earlier study identified E. coli bacteria in two dogs that proved resistant to 12 different antibiotics over the span of two weeks.2
Study Shows Cranberry Extract May Prevent UTIs
Recently, a team of researchers from the College of Veterinary Medicine at National Chung Hsing University in Taiwan conducted a study to determine the effects of cranberry extract on the development of urinary tract infections in dogs.3
They also wanted to measure the adherence of E. coli bacteria to canine kidney cells.
The team studied 12 pet dogs in one experiment, and six additional dogs in a second experiment. In the first experiment, the 12 dogs all had a history of recurrent UTIs (at least three infections in the previous year).
Six of the 12 received an antibiotic for two weeks, while the remaining dogs received cranberry extract for six months. Over the course of the six-month study, none of the 12 dogs developed a UTI.
In the second experiment, six dogs received cranberry extract for 60 days. In urine samples taken at 30 and 60 days, E. coli adhesion to kidney cells was significantly reduced compared to samples taken before the dogs began the extract. The researchers concluded that:
“Oral administration of cranberry extract prevented development of a UTI and prevented E. coli adherence to MDCK [canine kidney] cells, which may indicate it has benefit for preventing UTIs in dogs.”4
Translation: Cranberry extract appears to be as or more effective in preventing E. coli-related urinary tract infections in dogs as short-term antimicrobial treatment — without the side effects. In addition, cranberry extract can help fight multi-drug resistant bacteria in dogs with recurrent E. coli UTIs.
I recommend choosing an organic cranberry extract with D-mannose, which is a simple sugar closely related to glucose that occurs naturally in cranberries, peaches, apples, other berries and some plants.
D-mannose is fully absorbed (but does not prompt an insulin release or rock blood glucose levels, so there’s no negative systemic side effects) and quickly travels to the kidneys, then the bladder, and is excreted in urine.
D-mannose goes to work in your dog’s bladder, where it adheres to E. coli lectins. Almost all the D-mannose winds up in urine, which in turn coats the E. coli bacteria so it can’t stick to the walls of the bladder, and is rinsed out of the body when your dog urinates.
Symptoms of a Urinary Tract Infection
Some signs your dog may have a urinary tract infection include:
✓ Suddenly urinating in the house
✓ Constant licking of urinary openings
✓ Visible blood in the urine; dark or cloudy urine
✓ Loss of bladder control; urine dribbling
✓ Inability to pass urine; passing very little urine
✓ Vomiting, lethargy and lack of appetite
✓ Straining to urinate; crying out in pain
✓ Drinking more water than usual
These are all signals that may indicate a potentially serious issue with your dog's urinary tract or bladder. It's important to get your canine companion, along with a urine sample, to your veterinarian as soon as possible.
A urinalysis will provide valuable information about why your dog is having urinary problems. In addition to providing information about the presence of blood, protein, glucose, ketones and bilirubin, a urinalysis will also determine how well your dog can concentrate his urine, which is an indicator of kidney health.
The urinalysis will also detect white blood cells, which means there is inflammation or infection, and a urine culture and sensitivity can determine if bacteria is present, and what type, to help devise a treatment plan. If an infection is present, medication will be needed to treat the problem.
However, sometimes pets experience inflammation or crystals without any infection present. In this latter case, a different set of medications may initially be needed, but ultimately, in both situations, this is often a sign that it may be time to change your dog’s diet (more about that shortly).
The Importance of Urine pH in Urinary Tract Health
Dogs are carnivores and should have a slightly acidic urine pH of between 6 and 6.5. (The higher the urine pH, the more alkaline it is.) Vegetarian mammals like rabbits and horses naturally have a very alkaline urine pH (above 8.0). Human urine is slightly more alkaline (between 6.5 and 7), and many pet owners wrongly assume their dog’s body functions in the same manner as their own.
It’s important to keep your healthy dog’s urine pH slightly acidic (below 7), because urine maintains its natural defenses when kept in the appropriate 6 to 6.5 range. When the pH creeps up toward the alkaline side, the urine loses its natural defenses and creates a more hospitable environment for bacterial growth and the development of struvite crystals.
The flip side of the coin is a urine pH below 6, which can cause your dog to develop a different type of problem — calcium oxalate stones. If your dog has had one or more infections or other problems with the urinary tract, I recommend buying pH strips from your veterinarian or at the local drug store, to check her urine pH at home so you know when it’s in or outside the desired range.
You should collect urine samples in the morning before you feed your dog. You can either hold the pH tape in the stream of urine while your dog is voiding, or you can catch a urine sample in a container and dip the tape into the sample to check the pH. This should be done immediately with a fresh sample to insure accuracy.
The Right Diet for a Healthy Urinary Tract
In my experience, poor or improper diet is the culprit in the vast majority of cases of dogs with chronic urinary tract problems. A prescription diet, which many conventional veterinarians recommend, typically combines high-carb foods with medications to lower your dog’s urine pH. This is never my approach. Instead, I transition dogs to a diet that does not contain pro-inflammatory alkalizing carbohydrates.
When we feed carnivores a cereal-based diet, their urine becomes alkaline as a result. Meat-based diets are naturally acidic, whereas alkalizing starch-based diets are frequently the cause of chronic UTIs, because lack of acidity removes the antimicrobial activity in urine.
Alkaline urine can also create cystitis (irritation of the lining of the bladder), crystals, and even uroliths, or stones, that require surgery.
Often, a dog’s urine pH can be maintained naturally between 6 and 6.5 by feeding a species-appropriate diet. To reduce urine pH, you must feed a low-carb, starch-free, potato/tapioca/lentil-free (so no “grain free” dry foods), and preferably fresh or at least canned food diet for the increased moisture content.
There are products on the market to reduce urine pH that contain the acidifying amino acid DL-methionine. This is a safe addition to your dog’s diet, but a more logical approach is to simply stop feeding grains and alkalizing foods.