As with humans, water is a major component of the blood and healthy cells of cats. Originally, cats evolved to absorb most of their hydration through their food, from eating prey such as mice and birds which consist of around 70% water. Cats have a naturally low thirst drive, meaning that unlike dogs, who are typically not picky about where they obtain water, cats are more particular and slower to respond to dehydration. It is important that cats remain in a constant state of hydration to allow for frequent urination, which prevents development of uroliths (urinary tract stones). Water is also essential for joint lubrication and maintenance of optimal organ function.
Owners who transition from a dry to a raw or wet diet will notice a reduction in their cat’s water consumption, due to this higher dietary moisture content which mimics their natural diet. Raw and wet diets contain a moisture content above 63%, which is essential to maintain a hydrated state. Dry diets typically contain <10% moisture, and although cats are typically seen to drink more water on these diets, they do not drink a sufficient amount to compensate for the significant lack of dietary moisture.
Sodium use in dry diets is controversial. It is incorporated in processed diets to enhance water intake and increase urine volume to reduce the risk of urolithiasis. Additionally, it is added to make these dry diets more palatable to cats. However, increased sodium levels may be of concern due to their potential adverse effects in cats with hypertension and renal diseases. With dry diets, the urine can become alkaline and very concentrated, which encourages formation of uroliths.
Living with chronic dehydration can contribute to development of renal issues, as well as diabetes. Signs of dehydration in cats include reduced urination, lethargy, reduced appetite, sunken eyes, dull coat and pale or dry gums. Chronic kidney disease is prevalent in around 40% of senior cats, and 80% of geriatric cats, and although the aetiology is not well understood, research indicates dehydration as a risk factor.
How to increase your cat’s hydration
Change their diet. Dietary moisture is paramount for maintaining a healthy urinary tract and raw diets contain the correct level of moisture to maintain hydration in cats. This causes an increase in urine volume and dilution which helps reduce and prevent stone formation. Some owners also choose to mix a bit of additional water into their cat’s raw or wet food.
Chicken and quail eggs have a high water content, and the yolks are great when added as an occasional topper to your cat’s meal. They have an abundance of nutrients, are highly digestible and contain choline which helps prevents hairballs. Bone broth is also an excellent choice to aid a cat’s hydration, it can be mixed in with their food or given on its own as a tasty treat.
Cats often do not like having their water bowl situated next to their food bowl, due to the potential for water contamination. It is advisable to offer multiple water bowls, especially in multi-cat households, and to ensure water is also placed away from the litter tray.
Some owners may opt to use fountain bowls. Some cats seem more drawn to running water, as this mimics the flow of a fresh stream and may be more appealing. Although research has found no statistically significant difference of water intake between bowls and fountains, cats show different individual preferences and owners can experiment and find what works best for their cat.
Lucy James, BSc (Hons) Bioveterinary Science