Diagnosis and Management of Dehydration in Children

AMY CANAVAN, MD, AND BILLY S. ARANT, JR., MD

Am Fam Physician. 2009;80(7):692-696

Author disclosure: Nothing to disclose.

The most useful individual signs for identifying dehydration in children are prolonged capillary refill time, abnormal skin turgor, and abnormal respiratory pattern. However, clinical dehydration scales based on a combination of physical examination findings are better predictors than individual signs. Oral rehydration therapy is the preferred treatment of mild to moderate dehydration caused by diarrhea in children. Appropriate oral rehydration therapy is as effective as intravenous fluid in managing fluid and electrolyte losses and has many advantages. Goals of oral rehydration therapy are restoration of circulating blood volume, restoration of interstitial fluid volume, and maintenance of rehydration. When rehydration is achieved, a normal age-appropriate diet should be initiated.

Clinical dehydration scales based on a combination of physical examination findings are the most specific and sensitive tools for accurately diagnosing dehydration in children and categorizing its severity. Overdiagnosis of dehydration may lead to unnecessary tests and treatment, whereas underdiagnosis may lead to increased morbidity (e.g., protracted vomiting, electrolyte disturbances, acute renal insufficiency).

Among children in the United States, fluid and electrolyte disturbances from acute gastroenteritis result in 1.5 million outpatient visits, 200,000 hospitalizations, and 300 deaths per year.¹ Additionally, children may become dehydrated because of a variety of other illnesses that cause vomiting, diarrhea, or poor fluid intake.

Diagnosis

PARENTAL OBSERVATION

Parental report of vomiting, diarrhea, or decreased oral intake is sensitive, but not specific, for identifying dehydration in children. If parents report that the child does not have diarrhea, has normal oral intake, and has normal urine output, the chance of dehydration is low. Likewise, when parents are asked about physical signs of dehydration, a number of positive answers suggest dehydration. However, if the parents report normal tear production, the chance of dehydration is low.^2,3

PHYSICAL EXAMINATION

Comparing change in body weight from before and after rehydration is the standard method for diagnosing dehydration.⁴ To identify dehydration in infants and children before treatment, a number of symptoms and clinical signs have been evaluated and compared with this standard method. Physical examination findings during dehydration represent desiccation of tissue, the body’s compensatory reaction to maintain perfusion, or both. The most useful individual signs for identifying dehydration are prolonged capillary refill time, abnormal skin turgor, and abnormal respiratory pattern.⁵ However, clinical dehydration scales based on a combination of physical examination findings are much better predictors than individual signs. ⁵

In one study, four factors predicted dehydration: capillary refill time of more than two seconds, absence of tears, dry mucous membranes, and ill general appearance; the presence of two or more of these signs indicated a fluid deficit of at least 5 percent.⁶ In a similar validated scale, general appearance, degree of sunken eyes, dryness of mucous membranes, and tear production were associated with length of hospital stay and need for intravenous fluids in children with acute gastroenteritis.⁷

Capillary refill time is performed in warm ambient temperature, and is measured on the sternum of infants and on a finger or arm held at the level of the heart in older children. The measurement is not affected by fever and should be less than two seconds.⁸ Assessment of skin turgor is performed by pinching skin on the lateral abdominal wall at the level of the umbilicus. Turgor (i.e., time required for the skin to recoil) is normally instantaneous and increases linearly with degree of dehydration. ⁹ Respiratory pattern and heart rate should be compared with age-specific normal values.

LABORATORY ASSESSMENT

Unlike in adults, calculation of the blood urea nitrogen (BUN)/creatinine ratio is not useful in children. Although the normal BUN level is the same for children and adults, the normal serum creatinine level changes with age (0.2 mg per dL [17.68 μmol per L] in infants to 0.8 mg per dL [70.72 μmol per L] in adolescents). BUN alone and urine specific gravity also have poor sensitivity and specificity for predicting dehydration in children.¹⁰

In combination with a clinical dehydration scale, a serum bicarbonate level of less than 17 mEq per L (17 mmol per L) may improve sensitivity of identifying children with moderate to severe hypovolemia.¹¹ Additionally, a serum bicarbonate level of less than 13 mEq per L (13 mmol per L) is associated with increased risk of failure of outpatient rehydration efforts.¹²

Treatment

PATHOPHYSIOLOGY

Most of the volume loss in dehydration is extracellular fluid. The extracellular fluid space has two components: plasma and lymph as a delivery system, and interstitial fluid for solute exchange.¹³ The goal of rehydration therapy is first to restore the circulating blood volume, if necessary; then to restore the interstitial fluid volume; and finally to maintain hydration and replace continuing losses, such as diarrhea and increased insensible losses caused by fever.

ORAL REHYDRATION THERAPY

The American Academy of Pediatrics recommends oral rehydration therapy (ORT) as the preferred treatment of fluid and electrolyte losses caused by diarrhea in children with mild to moderate dehydration.¹⁴ ORT is as effective as intravenous fluid in rehydration of children with mild to moderate dehydration—there is no difference in failure rate or hospital admission rate between the two treatments.¹⁵ Additionally, ORT has many advantages compared with intravenous fluid therapy. It can be administered at home, reducing the need for outpatient and emergency department visits; requires less emergency department staff time; and leads to shorter emergency department stays. Parents are also more satisfied with the visit when ORT had been used.¹⁶ With ORT, the same fluid can be used for rehydration, maintenance, and replacement of stool losses; and ORT can be initiated more quickly than intravenous fluid therapy.¹⁷

The principles of ORT to treat dehydration from gastroenteritis apply to the treatment of dehydration from other causes. Altered mental status with risk of aspiration, abdominal ileus, and underlying intestinal malabsorption are contraindications. Cost to the family may be a deterrent to home ORT; therefore, ORT solution provided by the physician’s office or emergency department increases the likelihood that parents will use ORT and reduces unscheduled follow-up visits.¹⁶

Nasogastric rehydration therapy with ORT solution is an alternative to intravenous fluid therapy in patients with poor oral intake. Nasogastric hydration using oral rehydration solution is tolerated as well as ORT. Failure rate of nasogastric tube placement is significantly less than that of intravenous lines, and significant complications of nasogastric tube placement are rare. Nasogastric rehydration therapy is also less expensive than intravenous fluid therapy.¹⁸

As soon as children with acute gastroenteritis are rehydrated, a regular age-appropriate diet should be initiated. This does not worsen the symptoms of mild diarrhea, and may decrease its duration.¹⁴

Preparations. Use of an appropriate ORT solution, such as commercial electrolyte solutions for children (e.g., Pedialyte), corrects and helps prevent electrolyte disturbances caused by gastroenteritis.^17–19 The World Health Organization ORT solution contains 90 mEq per L of sodium, mimicking the sodium content of diarrhea caused by cholera. Commercial ORT preparations typically contain around 50 mEq per L of sodium, which is more consistent with the sodium content of diarrhea caused by rotavirus.²⁰ Commercial ORT solutions contain 25 g per L of dextrose, which helps prevent hypoglycemia without causing osmotic diuresis,²¹ and 30 mEq per L of bicarbonate, which leads to less vomiting and more efficient correction of acidosis. ¹⁹ Commercial ORT solutions are recommended over homemade solutions because of the risk of preparation errors.²² Clear sodas and juices should not be used for ORT because hyponatremia may occur. Table 1 compares the electrolyte composition of commercial electrolyte solutions with other clear liquids.

Administration. For mild dehydration, 50 mL per kg of ORT solution should be administered over four hours using a spoon, syringe, or medicine cup¹⁴; this can be accomplished by giving 1 mL per kg of the solution to the child every five minutes. Patients may be treated at home.¹⁴ If the child vomits, treatment should be resumed after 30 minutes.¹⁵ After the four-hour treatment period, maintenance fluids should be given and ongoing losses assessed and replaced every two hours. Maintenance therapy includes providing anticipated water and electrolyte needs for the next 24 hours in the child who is now euvolemic with expected normal urine output. The Holliday-Segar method (Table 2²³) is a simple, reliable formula for estimating water needs.²⁴ Based on average weights of infants and children, this method can be further simplified to provide maintenance ORT at home: 1 oz per hour for infants, 2 oz per hour for toddlers, and 3 oz per hour for older children. To replace ongoing losses, 10 mL per kg for every loose stool and 2 mL per kg for every episode of emesis should be administered.

For moderate dehydration, 100 mL per kg of ORT solution should be given over four hours in the physician’s office or emergency department. ¹⁴ If treatment is successful and ongoing losses are not excessive, the child may be sent home. At home, caregivers should provide maintenance therapy and replace ongoing losses every two hours as described for mild dehydration. ORT is considered to be unsuccessful if vomiting is severe and persistent (i.e., at least 25 percent of the hourly oral requirement) or if ORT cannot keep up with the volume of stool losses.¹⁷

Severe dehydration should be treated with intravenous fluids until the patient is stabilized (i.e., circulating blood volume is restored). Treatment should include 20 mL per kg of isotonic crystalloid (normal saline or lactated Ringer solution) over 10 to 15 minutes.²⁵ No other fluid type is currently recommended for volume resuscitation in children.²⁶ Treatment should be repeated as necessary, with monitoring of the patient’s pulse strength, capillary refill time, mental status, and urine output. Stabilization often requires up to 60 mL per kg of fluid within an hour. ²⁵ Electrolyte measurement should be performed in all children with severe dehydration and considered in those with moderate dehydration because it may be difficult to predict which children have significant electrolyte abnormalities.²⁷ After resuscitation is completed and normal electrolyte levels are achieved, the patient should receive 100 mL per kg of ORT solution over four hours, then maintenance fluid and replacement of ongoing losses. If ORT fails after initial resuscitation of a child with severe dehydration, intravenous fluid therapy should be initiated. First, 100 mL per kg of isotonic crystalloid should be administered over four hours, followed by a maintenance solution. This method also may be used when a child with moderate dehydration fails ORT.

The electrolyte content of intravenous maintenance fluid for infants and children with normal serum electrolyte levels should be 5 percent dextrose and 25 percent normal saline, plus 20 mEq per L of potassium. ^23,28,29 Intake, output, and vital signs must be checked every four hours, and adjustments made to the therapy as necessary (e.g., in the setting of ongoing losses, such as excessive stool output, or persistent fever). If stool output exceeds 30 mL per kg per day, it should be replaced in an equal volume every four hours with an intravenous solution comparable in electrolytes with the stool (50 percent normal saline plus 20 to 30 mEq per L of potassium), in addition to the volume of maintenance fluid, until ORT can be tolerated. Children with persistent fever may require 1 mL per kg per degree centigrade every hour, in addition to the calculated maintenance therapy. Postoperatively and in children with central nervous system infection or injury, 20 to 50 percent less fluid and fluid with higher sodium content may be needed because of abnormal antidiuretic hormone secretion.²⁸ These adjustments in fluid rates are guided by regular measurement of urine output and vital signs.

MEDICATIONS

Pharmacologic agents are not recommended to decrease diarrhea because of limited evidence and concern for toxicity. Although Lactobacillus has no major toxic effects, its effectiveness in patients with diarrhea has not been demonstrated.¹⁴ A single dose of ondansetron (Zofran) has been shown to facilitate ORT by reducing the incidents and frequency of vomiting and, therefore, reducing the failure of ORT and the need for intravenous fluid therapy.³⁰ Recurrent dosing of ondansetron has not been studied.

Complications

Hypernatremia, hyponatremia, and hypoglycemia occasionally complicate dehydration. Serum electrolyte levels should be measured in children with severe dehydration and in those with moderate dehydration that presents in atypical ways.

Hypernatremia (serum sodium level of greater than 145 mEq per L [145 mmol per L]) indicates water loss in excess of sodium loss. Because sodium is restricted to the extracellular fluid space, the typical signs of dehydration are less pronounced in the setting of hypernatremia, and significant circulatory disturbance is not likely to be noted until dehydration reaches 10 percent. Findings that may aid in the diagnosis of hypernatremia in children include a “doughy” feeling rather than tenting when testing for skin turgor, increased muscle tone, irritability, and a high-pitched cry.³¹ Hyponatremia is often caused by inappropriate use of oral fluids that are low in sodium, such as water, juice, and soda. If severe dehydration is present, a child with hypernatremia or hyponatremia should receive isotonic crystalloid until stabilized. If after initial volume repletion, hyponatremia or hypernatremia remains moderate to severe (serum sodium level of less than 130 mEq per L [130 mmol per L] or greater than 150 mEq per L [150 mmol per L]), replacement of the remaining fluid deficit should be altered, with a principal goal of slow correction.

In one study, blood glucose levels of less then 60 mg per dL (3.33 mmol per L) were detected in 9 percent of children younger than nine years (mean age 18 months) admitted to the hospital with diarrhea.²⁷ History and physical examination findings did not indicate that these children were at risk; therefore, blood glucose screening may be indicated for toddlers with diarrhea.

Severe Dehydration: Symptoms, Causes & Treatment

Severe hydration is a medical emergency. It’s important to know how to recognize this advanced state of dehydration and know what to do.

You may need intravenous fluids in an emergency room and other treatments to avoid organ damage and other health complications if you experience severe dehydration.

Children, older adults, and those who are pregnant are especially susceptible to serious health problems related to severe dehydration. Let’s take a look.

Dehydration defined

The body is in a state of dehydration when fluid levels drop to a point at which organs and bodily functions, such as circulation and respiration, can’t function normally. It occurs when the body loses more fluids than it takes in.

You can usually remedy mild dehydration by drinking water or drinks packed with electrolytes.

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• Heat. Excessive sweating due to extreme temperature exposure, such as being active in hot weather or spending too much time in a sauna, may cause dehydration.
• Illness. An illness that triggers bouts of diarrhea or vomiting can also rob the body of fluids in a short amount of time. If you’re vomiting or have diarrhea and you can’t keep down replenishing fluids, mild dehydration can progress into severe dehydration.
• Not drinking enough or often enough. You can also become dehydrated by not drinking enough to keep up with typical fluid loss.
• Medications. If you take certain medications, such as diuretics for high blood pressure, fluid loss may be quicker.

If you don’t notice the early signs of dehydration or you don’t rehydrate soon enough, you can move from being mildly to severely dehydrated.

Symptoms of severe dehydration include:

• Thirst. You may think that feeling thirsty is the first indication that you may become dehydrated. The reverse is usually true: Your body starts to feel thirsty after dehydration has already started.
• Peeing less. In addition to feeling thirstier than usual, the signs of dehydration include less-frequent urination and darker colored urine.
• Not peeing. If you’re not urinating at all, it’s likely you’re severely dehydrated and should get immediate medical attention.
• Not sweating. Without enough fluids to function normally, your body can start to overheat, which can quickly lead to heat-related illnesses, such as heat stroke and heat exhaustion.
• Headache and dizziness. Dizziness and lightheadedness are signs of mild or moderate dehydration. If those symptoms worsen and you have trouble concentrating and communicating, seek medical attention.
• Poor skin turgor. Poor turgor is when your skin takes longer to return to its original appearance after lightly pinching an area.

Severe dehydration can lead to brain damage and even death in some cases.

Older adults need to be especially mindful of staying hydrated as they may be less aware of when they’re thirsty and becoming dehydrated.

Skin fold and dehydration

You can get a sense of how dehydrated you are by pinching or folding your skin between the pads of two fingers. If you pinch the skin on your arm, for example, it should quickly return to its normal appearance once you let go. The term for this kind of skin elasticity is turgor.

If the skin appears to “tent” or sticks together under the surface, it’s usually a sign that you’re severely dehydrated.

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In very young children, severe dehydration may be the case when they have:

• no tears accompany crying
• signs of lethargy
• dry diapers for longer than usual
• cold, clammy limbs

Serious health consequences can happen fast in children if severe dehydration isn’t treated quickly.

Symptoms of severe dehydration during pregnancy include:

• extreme thirst
• sunken eyes
• rapid heart rate
• drop in blood pressure
• dry mouth
• dry skin, as well as poor turgor
• early labor

Dehydration can also trigger Braxton-Hicks contractions, which feel like real contractions, but are considered to be signs of false labor.

Rehydrating through severe dehydration usually requires more than providing water or other beverages.

Treatment with intravenous fluids should begin as soon as you can get medical care.

IV fluids are usually a saline solution, made of water, sodium, and other electrolytes. By getting fluids through an IV rather than by drinking them, your body can absorb them more quickly and recover faster.

While in the hospital, your blood pressure and heart rate will probably be monitored to make sure they return to normal as your body recovers.

You’ll also be encouraged to drink water or other hydrating beverages, too.

For children

While sport drinks do contain a lot of added sugar, they also contain water and important electrolytes, such as sodium and potassium.

• A diluted sports drink — 1 part sports drink to 1 part water — may be helpful for children.
• Try giving very young children diluted sports drinks or water a teaspoon at a time. If swallowing is difficult, try using a syringe.

This can help keep fluid levels in a healthy range after mild dehydration or IV rehydration treatment.

When you’re pregnant

You can also rehydrate with water or sports drinks. If you feel nauseated in the morning or any time of day, try to find a time when you’re feeling better to get your fluids down.

Good drinks for rehydrating

Along with water and certain electrolyte sports drinks, soup, milk, and natural fruit juices all count as rehydrating beverages.

Drinks to avoid

Keep in mind that not all beverages help with rehydration.

• Colas and sodas. Sugar-sweetened soft drinks can actually make your dehydration worse and lead to further kidney-related dehydration problems.
• Alcohol, including beer. As refreshing as a cold beer might sound when you’re exceptionally thirsty, you should avoid alcohol if you’re trying to rehydrate.
• Caffeinated drinks. Caffeinated and alcoholic beverages act as diuretics, causing you to urinate more than usual and increasing your fluid loss compared to your fluid intake. This includes coffee, black tea, green tea, and energy drinks.

Severe dehydration is a potentially life-threatening medical emergency. It can cause serious damage to your kidneys, heart, and brain. To avoid severe hydration, respond to signs of dehydration by drinking fluids that rehydrate you.

You can also avoid even the hint of dehydration if you consume fluids throughout the day. How much you should drink depends on several factors, including your age, weight, and overall health.

People with kidney disease, for example, need to drink less than other individuals. People who are physically active need to drink more than others.

If you’re not sure, talk to your doctor. You can also do a quick check by looking at the color of your urine. If you’re peeing regularly each day and the color is almost transparent, you’re probably well hydrated.

Dehydration in cats. How to increase the water intake of cats

Anatoly Chernikov

K.I. Scriabin (2009). Specialist in dentistry, gastroenterology, endoscopy. Regularly takes part in domestic and international Veterinary Conferences: “Moscow International Veterinary Congress”, National Veterinary Conference (NVC), “Congress of the European Association for Veterinary and Comparative Nutrition” (ESVCN), “Southern European Veterinary Conference” (SEVC), International Community Conference Felinological Medicine (ISFM), Conference of the Russian Gastroenterological Academy (RGA), International Veterinary Conference Purina Partners.

Water is the basis of life. It is an indispensable nutrient and is critical for a variety of physiological functions, in particular, the regulation of metabolic processes and the excretion of metabolic products through the organs of the urinary system. The need of cats for water is underestimated. Normal saturation of the body with water is necessary to maintain an optimal balance of electrolytes, minerals and fluids.

The ancestors of the domestic cat, as inhabitants of arid areas, in the process of evolution received a unique ability to concentrate urine and, thus, retain water in the body. Cats are one of the few animals that can meet their fluid needs by relying almost entirely on prey: the average moisture content of typical feline prey is over 60%. When their diet is dehydrated, cats tend to compensate for the most by increasing urine concentration rather than the amount of water they drink, which allows them to survive on less liquid than dogs and answers the burning question: why does a cat drink so little? However, over time, a lack of fluid can deplete the reserves of the urinary system and serve as one of the main prerequisites for its diseases.

Healthy cats with free access to a source of drinking fresh water with adequate water intake can maintain a normal water balance by eating food with a wide range of moisture: from dry (less than 10%) to wet (70% and above). But sometimes animals of this species cannot provide adequate hydration to their body. In particular, with kidney disease, diabetes mellitus, as well as syndromes manifested by vomiting and diarrhea, which cause increased fluid loss in the body, or anorexia and adipsia, in connection with which the intake of moisture decreases. Increased water intake in cats is indicated in animals with lower urinary tract disease and in the prevention and treatment of obesity. The causes of dehydration in cats are not always obvious, but their detrimental effect on the animal’s body is enormous.

Signs of dehydration in cats

It is worth noting that a healthy cat is 60% water. Dehydration in a cat even by 5% can affect metabolism and serve as a trigger factor for exacerbation of diseases. Decreased hydration or dehydration in a cat by less than 10% is manifested by the following symptoms:

• dry mucous membranes,
• violation of skin turgor,
• increased thirst,
• tachycardia,
• tachypnea,
• deterioration of capillary refill.

With the degree of dehydration of the body by 10-15%, a lethal outcome is possible [1,2,3].

There are three degrees of development of dehydration in cats:

1. Mild degree of dehydration – characterized by a decrease in hydration in a cat by less than 5%.

The danger of this stage lies in the fact that it is difficult to notice, since there are almost no symptoms. You can suspect a problem by a slight decrease in the cat’s activity, as well as by the nose – in a healthy animal, it should be wet and cool. A dry and warm nose can normally be found in a sleeping cat.

2. Average degree of dehydration – hydration deficit is 5-10%.

Distinctive features – dryness and pallor of the oral mucosa, sticky and viscous saliva.

3. Severe dehydration – water deficit of 10% or more.

Signs – a marked decrease in activity, increased drowsiness, decreased appetite, anorexia, increased heart rate, shortness of breath. The cat prefers to lie in the dark, away from noise and bright light. Only a veterinarian can save a cat with dehydration at the last stage.

The amazing and in its own way unique compensatory mechanism that allows cats to concentrate their urine while consuming even small amounts of water can have a significant negative impact on their health. This is why the question of natural hydration of cats and methods of stimulating water intake are important for the veterinarian and owner.

How much water does a cat need? environment, composition of the diet) [1]. Based on the data obtained, it is possible to estimate how much water a cat should drink.

Due to the wide variability of factors affecting water requirements, there is no single recommendation for all animals. However, the US National Research Council (NRC) recommends determining the amount of moisture required for healthy animals at the rate of 1 ml of water for every 1 kcal of feed consumed (but not less than 26 ml per 1 kg of body weight per day) [3]. To estimate the energy requirements of a cat under hospital treatment (RER), you can use the formula: 70 x Animal weight (kg) 0.67. Of course, when assessing the needs of sick cats, one should pay attention to additional water losses depending on the pathological condition.

Table 1: Basic daily energy requirement for an adult cat kcal/kg bw [3, 4]

What water sources should be considered for cats?

Excluding parenteral nutrition, cats have three main sources of water: dietary, drinking and metabolic [1]. When determining the amount of water, it is important to consider all three sources.

Diet water

The amount of moisture in the finished industrial feed ranges from 70%. Dry foods typically contain less than 10% moisture. Thus, an animal fed a dry diet needs a source of clean drinking water. At the same time, a healthy cat eating only wet food can meet the basic, that is, the minimum requirements for water, without additional sources of fluid.

Drinking water

Regardless of the type of diet, it is necessary to provide the cat with a source of fresh drinking water and ensure that it is adequately consumed. What other recommendations can be given to increase the water intake of cats?

There are not many studies that cover the topic of drinking habits of cats [5]. Standard recommendations include separating eating and drinking areas, and using wider and shallower drinking bowls.
Drinking water can be provided by stagnant water (bowls) or running water from a fountain, dripping faucets. It is traditionally believed that cats drink running water better. However, poll 549of cat owners in Germany and Austria showed that, given both options for water sources, cats preferred standing water to a fountain. Respondents also did not note preferences in the bowl material (ceramics, metal, glass) [5].

Metabolic water

During the catabolism of macronutrients during the production of ATP, one of the products of the reactions taking place is water. So each gram of protein, fat and carbohydrates provides 0.41; 1.07; 0.6 grams of water, respectively. On average, the metabolism of 100 kcal leads to the formation of 10-16 ml of metabolic water [1].

Fluid Therapy

If your pet is dehydrated, fluid therapy is indicated. Water can be administered parenterally (intravenously – in the form of droppers, subcutaneously, intraosseously, and so on) if oral administration is impossible or insufficient [1]. During hospitalization, intravenous fluid therapy is used to manage the cat’s signs of dehydration, meet basic water needs, and compensate for additional fluid losses. A thorough daily assessment of the cat’s condition is required to correct and calculate fluid volumes.

When cats benefit from increased water intake

Diseases associated with high fluid loss and lack of fluid in the body increase the risk of dehydration. Particular attention should be paid to conditions and diseases accompanied by polyuria and polydipsia, since fluid loss is mainly carried out through the urinary system.

Diseases associated with dehydration

Chronic kidney disease is a common disease in cats [6]. It is accompanied by loss of the ability of the kidneys to concentrate urine, polyuria and compensatory polydipsia as the main clinical features. Dehydration in cats in these cases further aggravates the course of the disease by negatively affecting renal perfusion [7]. Most often, these conditions require parenteral fluids (CKD when dehydration or uremia occurs). Diabetes mellitus is also accompanied by polyuria and can lead to dehydration [8]. Animals with any disease that is accompanied by vomiting, diarrhea, bleeding, anorexia may also have problems with hydration of the body. An experienced veterinarian can give advice on how to prevent dehydration in cats.

Thus, the treatment of any pathological condition, accompanied by a decrease in water intake and/or an increase in water loss, can be supplemented by the use of various strategies to increase fluid intake, using different sources of water for cats.

Lower urinary tract disease (FLUTD)

Increased water intake in cats results in increased volume and decreased urine concentration, which may be of interest in the treatment of urolithiasis and feline idiopathic cystitis (FIC). This strategy is widely recommended by the American College of Enteral Veterinary Medicine (ACVIM) for the treatment of urolithiasis [1]. The rationale for this is that increasing water intake and diluting urine helps to reduce the concentration of urolith precursors and inflammatory mediators. Also, higher water intake in cats increases the frequency of urination and reduces the residence time of urolith precursors and other substances in the lower urinary tract. The recommended density of urine to achieve a positive effect is 1.030 or lower.

Urolithiasis (UCD) is a complex condition in which many factors can influence the formation of uroliths, including urinary pH, concentrations of urolith precursors and crystallization inhibitors, and overall water intake. There are studies demonstrating the effectiveness of high-moisture diets for both the treatment and prevention of KSD in cats [9,10].
As for FCI, unambiguous data on a significant positive effect of dietary moisture on this disease as an independent strategy for treatment and prevention are currently insufficient and the issue requires further research.

It can be said that the promotion of water intake and especially the use of diets above 70% moisture when used in combination with other strategies may be beneficial in the treatment and prevention of urolithiasis and idiopathic cystitis in cats.

Prevention and treatment of obesity

Increasing the moisture content of the diet leads to an increase in the amount of food consumed and a decrease in its energy density. The energy density of wet food ranges from 0.6 to 1.5 kcal/g, while the energy content of dry food is usually above 3 kcal/g. It is certainly possible for a cat to increase the daily caloric intake by increasing the total amount of food consumed, but there are studies demonstrating the clear effectiveness of wet diets in the prevention and treatment of obesity.
Moreover, dilution of dry diets with water has also been shown to be clinically effective in combating obesity. Some studies suggest that a high moisture diet can increase physical activity and alter activity patterns in cats, also influencing weight loss, but this needs further study [11,12,13,14].

What should I do if my cat is dehydrated? Strategies for increasing water intake

How can I get my cat to drink enough water? To understand why a cat is dehydrated and to recommend the best method for encouraging water intake, the clinician must take a history and understand the causes of dehydration. As concomitant recommendations for the treatment of the underlying disease, recommendations should be made to increase fluid intake and prevent further development of dehydration.

There are several strategies for increasing fluid intake to ensure adequate hydration and/or reduce urine concentration. If the goal is not achieved with one strategy, some of these techniques can be combined.

Using wet diets or adding water to dry foods

What to feed a dehydrated cat? The easiest way to increase your water intake is to use a wet diet. In this case, the moisture content of the diet rises to 60% – 80%. This information is available on the wet food label (moisture is not always listed on dry food packages).

However, feeding wet diets is sometimes not possible: not all cats like wet food, and for some owners, this option may be too expensive. Also, animals may require a special diet for the treatment of comorbidities that exists only in a dry form (for example, diets with hydrolyzed protein). In these cases, adding water to dry food can be an effective option to replace a wet diet.

The use of such diets does help increase water intake and reduce urine density, although there is high individual variability due to the large number of factors (diet, type of disease, activity, environmental factors, and others) that affect these processes. Thus, to achieve the desired effect (density less than 1.030) when changing the moisture content of the diet, it is necessary to monitor urine tests. In the future, the amount of water consumed can be adjusted in accordance with the targets for urine density.

Changing the composition of the diet

There are several dietary factors that affect urine volume and density, in addition to the water content of the diet. These include protein content, mineral composition and concentration of minerals. In particular, an increase in the sodium content in the diet (>2.5 grams per 1000 kcal) contributes to an increase in thirst and, as a result, an increase in water consumption [15]. Such a nutritional strategy may be useful in reducing urine density in the treatment of lower urinary tract diseases. It is worth noting that using this method seems to be effective only if the cat is provided with sufficient water.

Promotion of drinking water intake

How to stimulate water intake in cats? This can be done, as mentioned above, by changing the composition of the diet and increasing the salt content, as well as using various strategies to encourage cats to drink. Evidence for the effectiveness of these strategies is lacking, but due to safety, their use is widespread. This is especially important in cases where the use of high-moisture diets does not lead to the expected results.

How to give a cat water to increase fluid intake? You can use fountains or, conversely, stagnant water, experiment with the size of bowls and the materials from which they are made, praise the cat when drinking water, or, conversely, let it retire with a bowl. It is best to use several containers of water placed around the apartment in different places. At the same time, it is important to ensure that the water is always fresh and clean, as well as regular cleaning and disinfection of bowls.

Flavored water

Chicken broth (unseasoned) or tuna “water” (liquid preserved in fish’s own juice) can be added to drinking water. Some cat owners also use lactose-free milk or cow’s milk diluted in water. Unfortunately, there are no published studies on the effect and safety of adding such products to water.

Nutrient-fortified water

There are three published studies [16,17,18] on the use of nutrient-fortified water in healthy cats without changing feeding patterns. So in the study of M.B. Zangi in 18 cats for 56 days was assessed the level of fluid intake. During the first week, all animals remained in their original state and the only source of moisture for them was tap water (WW). After that 9cats were given only nutrient-fortified water (NW) for 10 days and then, until the end of the study, both NF and BB in separate bowls, swapped. The remaining 9 animals still received only BB. Throughout the study, blood and urine samples were taken from the animals, and total body water content, lean body mass, and fat mass were assessed by quantitative MRI.

The study demonstrated that animals fed nutrient-fortified water exhibited higher fluid intake, which contributed to a decrease in urine density.

There are now special products that can increase the water intake of cats. For example, such as
Purina® PRO PLAN® HC Hydracare. This product is a liquid, non-complete cat food that contains osmolytes and is highly palatable to cats. The use of this food as a standalone product, provided to the cat in a separate bowl, leads to an increase in the variety of available water sources and, as a result, additional stimulation of fluid intake. It also increases the overall level of hydration.

Conclusion

The role of water as an essential nutrient cannot be overestimated. Healthy cats, due to natural evolutionary physiological mechanisms of urine concentration, are able to maintain an adequate level of hydration over a wide range of water intake. However, in many cases, the use of hydration promotion strategies can be extremely beneficial. So, many diseases are accompanied by conditions associated with increased water loss, and animals with anorexia often suffer from adipsia – all this leads to a rapid violation of the hydration of the body with the ensuing consequences.

A growing body of evidence suggests that promoting water intake is also desirable in animals with lower urinary tract diseases such as urolithiasis and idiopathic cystitis. Many clinicians have successfully used dietary approaches with a high daily intake of water to treat and prevent obesity.

Encouragement of water intake is especially important in cats, which are generally poor drinkers and tend to produce highly concentrated urine. The use of modern nutritional approaches in combination with other strategies is an important therapeutic support that every veterinarian should keep in mind.

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