Bladder stones are a common problem for lots of dogs. It can be painful and a lifelong issue, but luckily most bladder stones can be prevented with a good diet!

What are they? Bladder stones are minerals that clump together like rocks in the bladder. Over time they can become so large that they get trapped in the bladder - which as you can imagine is very painful.

Symptoms include:

blood in urine
pain when urinating
needing to pee a lot

Smaller dogs are more likely to be affected. Common breeds affected include cocker spaniel, miniature poodle, miniature schnauzer, shih tzu, dachshund, and bichon frise.

There are two main types of bladder stones: struvite stones and calcium oxalate stones. There are several other types of bladder stones but these two make up the majority (over 85%) of cases.

Struvite stones

Struvite stones are the most common type of bladder stone. They usually form after a bladder infection with a specific type of bacteria that produces an enzyme called urease. This enzyme produces ammonia which makes the urine more alkaline. Over time these conditions cause bladder inflammation and ultimately the formation of struvite crystals.

Struvite stones are most common in female dogs. They can often be resolved using food, after first getting rid of the bacterial infection. In more serious cases surgery is necessary to remove the stones.

Diet plays a huge role in both treatment and prevention.

Calcium oxalate stones

Calcium oxalate is also a common type of bladder stone. The cause is less obvious but the predominant causes are diet, metabolic issues and a genetic predisposition to stone formation. Dogs with this type of stone may lack something called nephrocalcin in their urine which naturally inhibits stone formation.

Calcium oxalate stones are more likely to occur in male dogs that are overweight, under exercised and fed kibble.

Unfortunately these stones typically require surgical intervention to remove. Because they cannot be resolved with diet, the focus is on using food to reduce the likelihood of stones forming again.

Approximately 50% of dogs with calcium oxalate stones will have a reoccurrence within two years. This tells me that the conventional method of prevention (most commonly a prescription kibble diet) is not very effective!

Urine concentration & pH

The biggest contributing factor to bladder stone formation is how concentrated the urine is. Dehydrated dogs have very concentrated pee, which significantly increases the risk of developing bladder stones.

This occurs because kibble is a dehydrated product. It contains around 6% moisture compared to around 70% moisture in meat based food. With so many dogs eating processed kibble it’s no wonder then that many dogs suffer from bladder stones. Simply offering more water or pouring water over dry food doesn’t fix the problem, it needs to be in the actual food itself.

The other important factor is that healthy dogs have slightly acidic urine. Raw fed dogs have a urine pH of 6-6.5 (slightly acidic) while kibble fed dogs have a urine pH of 7-8 (slightly alkaline). Feeding a fresh meat based diet is the most effective way to manage the pH of your dogs urine because their digestive system is designed for meat.

Diet for struvite stones

Typically a veterinarian diet for struvite stones involves reducing levels of protein, magnesium and phosphorous while lowering urine pH with a chemical called potassium citrate.

They don’t worry about kibble being 50% carbohydrate (which increases urine alkalinity) or that kibble is only 6% moisture (which increases urine concentration).

I don’t believe this is a rational approach.

The primary dietary factors are to reduce urine concentration and to reduce urine pH. The best way to achieve both of these goals is to feed a properly balanced raw diet made mostly with quality meat. A high proportion of meat will naturally improve the urine concentration as well as lower the urine pH to the optimal 6-6.5 zone.

Struvite stones are commonly seen alongside reoccurring bladder infections. It follows that the other primary objective is to reduce bladder infections from occurring in the first place. Cranberry extract has been shown to help to prevent urinary tract infections so is a good dietary addition if you are concerned. There is also evidence that probiotics are a safe and effective way to reduce UTIs.

Diet for calcium oxalate stones

Calcium oxalate stones are more difficult to deal with. Once formed diet is unlikely to help remove these stones, and they will most likely need a surgical intervention to remove them. The trick is to stop them from reoccurring.

Typical veterinarian advice is to increase urine pH, lower calcium and sodium, and to avoid ingredients containing oxalates.

High oxalate foods to avoid:

Grains (wheat, barley, bran)
Beetroot
Sweet potato
Legumes
Spinach & swiss chard

Urine pH affects crystal formation, with the optimal pH to prevent this being around 7.The pH for a raw diet will be slightly more acidic so this does need to be considered. Remember that prescription kibble mainly contains grains and might have high oxalates, making this choice complicated.

Reducing calcium below NRC guidelines is unwise in my view. Low calcium has been shown to be detrimental to your dogs health and should be avoided. Calcium affects the absorption of phosphorous in the body so it is more important to make sure they are in the right ratio. The ideal ratio is about 1.3:1 with slightly more calcium than phosphorous.

Finally there is evidence that probiotics can help break down oxalates which can help in the prevention of stone formation.

Prescription kibble vs raw food

Prescription vet diets are marketed as the only solution for dogs with bladder stones. It’s a great business model as the dogs need to be on them for life!

Aside from the low quality ingredients (seriously, look as the list) and high temperature processing (which destroys nutrients and denatures protein molecules) there are a couple of specific reasons why I don’t tend to agree with prescription food for bladder stones.

One big issue is that kibble is a dehydrated product, meaning that it does not contain moisture and concentrates the urine. Dogs with bladder stones need to have as diluted urine as possible to help prevent the formation of stones. For this reason in my opinion kibble or dehydrated food is not appropriate for dogs with bladder stones.

The other big issue is that alkaline urine is a primary factor in the formation of struvite bladder stones. Foods that are high in carbohydrate like kibble (even the expensive premium stuff) causes the urine to be alkaline. Foods that are made predominantly with raw meat cause the urine to be slightly acidic - which is what the bladder is naturally designed for.

For me, a properly formulated raw diet made with high quality ingredients will always be better than an expensive kibble. Just look at the ingredients 🐾