Exploring Cat and Dog Nutrition

Exploring Cat and Dog Nutrition We explore in plain everyday language the biological and species appropriate nutritional requirements of cats and dogs. Jones

Tune into our Podcast and watch for the soon to be released book Exploring Cat and Dog Nutrition by Sean B.

04/01/2025

When we think of hydration for our pets, we often focus on filling their water bowls. But just like in humans, hydration is not only about how much water pets drink, but also how much their bodies actually retain and utilize vs. just produce more urine output. Moisture-rich foods play a critical and often superior role in maintaining proper hydration in dogs and cats—especially given their unique physiology and evolutionary history.

Hydration Challenges in Dogs and Cats
Cats: Naturally Poor Water Drinkers
Domestic cats evolved from desert-dwelling ancestors (Felis lybica) who obtained nearly all their hydration from prey. As a result, cats have:

A low thirst drive, even when mildly dehydrated

Highly concentrated urine, which conserves water but stresses the kidneys

A preference for moisture from food over still water

This makes cats particularly vulnerable to chronic low-grade dehydration, which contributes to urinary tract disease and kidney issues—a leading cause of feline mortality.

Dogs: More Adaptive, But Still at Risk
Dogs, unlike cats, have a better thirst response but still benefit greatly from hydration through food, especially:

During exercise or hot weather

In older dogs, whose kidney function or thirst cues may decline

When eating dry kibble, which contains as little as 6–10% moisture

Moisture-Rich Diets Are Superior To Dry Diets
A dog or cat eating a dry diet must compensate by drinking significantly more water. But studies and field observations show this rarely happens to the degree required—especially in cats.

Physiological Benefits of Moisture-Rich Food
1. Better Water Retention
Moisture-rich foods hydrate more gradually and thoroughly, helping reduce water loss through urine. This is critical in:

Cats, where higher water intake via food is associated with reduced risk of FLUTD (Feline Lower Urinary Tract Disease)

Dogs, where hydration supports joint health, digestion, and thermoregulation

2. Supports Kidney Function
Adequate hydration via food dilutes waste products like urea and creatinine, reducing the kidneys’ workload and potentially delaying chronic kidney disease progression.

3. Improved Digestive Health
Hydrated food assists in smoother digestion and prevents constipation, particularly in cats and aging pets prone to GI sluggishness.

Scientific Evidence
A study in the Journal of Feline Medicine and Surgery found that cats on high-moisture diets produced more dilute urine and had lower incidence of urinary crystals and stones 【Markwell & Buffington, 1994†J Feline Med Surg†】.

Research in Veterinary Medicine showed that dogs fed canned food had significantly higher total water intake and lower urine specific gravity, indicating better hydration, even when their water bowl intake was unchanged 【Zanghi, 2016†Vet Med (Auckl)†】.

Another study showed that feeding wet food improved renal markers in aging cats and reduced dehydration-related complications 【Hall et al., 2003†J Vet Intern Med†】.

Feeding Recommendations
For Dogs and Cats:
Incorporate moisture-rich meals daily: wet food, gently cooked, raw, or rehydrated freeze-dried.

Aim for 70–80% moisture in at least one meal per day.

Use broths, goat’s milk, or hydrating toppers to boost moisture if feeding kibble.

Special Populations That Benefit Most:
Senior pets

Cats with urinary issues

Dogs with high activity levels

Pets prone to constipation or kidney concerns

Conclusion
Hydration for pets goes far beyond the water bowl. Moisture-rich foods mimic a natural prey-based diet and provide superior hydration, enhance kidney function, and reduce the risk of disease—especially in cats. Whether through raw, cooked, canned, or rehydrated foods, feeding water through food is one of the most effective health strategies you can adopt for your dog or cat.

References
Zanghi, B.M. (2016). “Evaluation of the hydration status of adult dogs fed a moisture-rich diet.” Veterinary Medicine (Auckl), 7: 209–217. https://doi.org/10.2147/VMRR.S103651

Markwell, P. J., & Buffington, C. A. (1994). “The effect of diet on lower urinary tract diseases in cats.” Journal of Feline Medicine and Surgery.

Hall, J. A., et al. (2003). “Effect of dietary moisture on renal function in cats.” J Vet Intern Med, 17(5), 660–665. https://doi.org/10.1111/j.1939-1676.2003.tb02498.x

National Research Council (2006). Nutrient Requirements of Dogs and Cats. The National Academies Press.

03/23/2025

A NOTE ON FOOD RESTRICTION IN OVERWEIGHT DOGS....

That post this morning got me thinking.

Food restriction studies in dogs, cruel as they seem and sometimes are, have shown us that if you feed dogs a touch less of their diet each day (20%) they do better, might even live longer, suggesting over-feeding is at play.

In fact, recently, we learned just one food meal a day for a dog instead of two seems to bestow health benefits including gastrointestinal, dental, orthopedic, kidney/urinary, and liver/pancreas conditions. The study, conducted by the Dog Aging Project, looked at data from over 24,000 dogs did not look at the type of food fed, sadly.

Now, MASSIVE CAVEAT here - you can't just slash the QUANTITY of food fed to a dog without a little prior consideration.

For example, complete dry food is made to MINIMUM standards. And they can't even manage to provide that. Studies show us 2/3 of complete dry dog food sold in the UK (and 94% of complete cans) fail to provide the MINIMUM nutritional needs to your pet at the recommended dose!

So, if you feed 20% less of a junk food like that you WILL go into nutritional deficiency over time.

And "light" dry pet foods are worse again. Studies show they just jack up the indigestible component of the kibble with cellulose, like a runway model chewing tissue before a show. These light dry foods are shown to result in nutritional deficiencies while leaving dogs hungry, massively increasing begging and scavenging behaviour.

The poor dogs starve on that crap.

For reasons known only to them, they insist on keeping the carb content up in these products! Does that make sense to you?! Like going to the gym on 50% bread rolls, as I keep saying. Yes, dogs in a cage can lose weight this way but when studies show simply replacing the carbs with more protein results in better weight loss endpoints (more weight loss WITH retention of LEAN body mass, crucial to the whole thing) why would you go any other way?

For overweight dogs fed real food it's much easier - you need to ensure your meaty mixes are lean, 3 or 4 parts protein to fat. That's the first step to slashing calorie intake - smarter meat inclusions / dodging crap, cheap, fatty raw dog food. At that, with careful attention on the treat end of things, the weight will slowly come off, lean muscle mass will stay in place and nutrients will stay topped up (they’re in the red meaty bit…).

Only with food and treats addressed in that manner can you think about reducing the amount of food fed to an overweight pet.

Once you have done that by 10%, 15% then say 20% (measure twice monthly), with no improvement after a few months, get the thyroid checked.

03/14/2025

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