The basics of canine hydration: what dogs need and why

Is your dog getting enough water? Here’s what you need to know about canine hydration and the important role of electrolytes!

You know that life cannot exist without water. But do you know how your dog’s hydration needs differ from your own? This blog provides an overview of how water regulation differs in humans and dogs, with a focus on the physiology of canine dehydration and overheating — conditions that can quickly become life-threatening.

Why water matters

Providing your dog with constant access to fresh water ensures he never goes thirsty. But its benefits don’t end there! Water also maintains the health of his cells, tissues and organs, supports his metabolism, transports nutrients and waste, regulates his body temperature and lubricates his joints (see Figure 1).

The role of electrolytes and nutrients

Water makes up approximately 60% of the weight of healthy, non-obese animals and is divided into different compartments or spaces – either inside cells (the intracellular compartment) or outside cells (the extracellular compartment). The intracellular compartment is the largest, containing 2/3 of the body’s water. The remaining 1/3 of body water is found in the extracellular compartment.

Plasma (a component of blood) contains water and solutes (e.g. electrolytes, minerals, sugars, proteins, amino acids, enzymes, etc.) that support normal cell function. These substances are often measured as an indicator of whole-organism health – and without adequate water, these substances deplete quickly!

The different hydration needs of dogs and humans

Panting is a strategy for heat dissipation that dogs share with other mammals, but not humans. Sweating is uniquely human.

Panting is a type of rapid breathing that enables heat dissipation through evaporation. Air is warmed and humidified upon intake. Heat is dissipated and water is lost through evaporation when the dog breathes out. Naturally, more vigorous exercise generates more heat. In dogs, this results in panting harder to dissipate more heat – an action that dogs are exceptional at!

In humans, heat dissipation involves profuse sweating with subsequent evaporative cooling, salt loss, and flushing of the skin. Dog skin not only lacks sweat glands and a robust network of cutaneous blood vessels (with the exception of their footpads) but also is covered by a layer of fur that provides insulation from the environment.

Dehydration: what are the signs?

How can you tell if a dog is dehydrated? Mild dehydration (5%) can be characterized by dry mucous membranes and lack of skin elasticity, while moderate dehydration (6%-8%) increases heartrate. More intense dehydration reduces performance in exercising dogs, and severe dehydration (8%-10%) will impact pulse quality and capillary refill time. Electrolyte loss and dehydration from any cause can become life threatening, with serious clinical signs including hypotension, hypothermia, weak to absent pulses, cold extremities, and/or altered mental abilities.

“So how much water does my dog need?”

Normal daily water intake for healthy dogs at maintenance (no excessive physiological demands, no illness, and/or no environmental/exercise-induced heat stress) can be found in Table 1. In such conditions, water is lost in urine and feces, and to a much lesser extent, via evaporation from the respiratory tract and footpads. Water loss via the respiratory tract will increase when there is a demand on a dog’s body to dissipate heat through panting. In other words, the harder your dog pants, the more water he needs!

There is no universal scientific consensus on what the daily water needs are in either dogs or humans because there are so many variables beyond the maintenance levels listed in Table 1, including but not limited to breed, age, ambient temperature, humidity, activity level, body composition, diet, conditioning, and acclimatization. But regardless of how much water he needs, providing him with constant access to fresh water is the best way to keep him hydrated. Electrolytes designed for dogs can also be added to water.

Several studies have found that:

  • Dogs acclimated to work and the environment were more likely to increase fluid consumption and hydration when provided a flavored oral electrolyte solution (Otto et al., 2017).
  • Dogs increase water intake when offered nutrient-enriched water (Zanghi and Gardner, 2018).
  • Oral pre-exercise hydration strategies for working dogs in hot environments (water, chicken-flavored water, and chicken-flavored electrolyte solution) suggested that electrolyte enrichment may reduce muscle injury and help dogs maintain lower peak temperatures (Niedermeyer et al., 2020).
  • Access to nutrient-enriched water reduced exercise-induced hyperthermia and improved pulse rate recovery in a population of working dogs (Zanghi et al., 2018).

Special considerations

There are a significant number of health conditions that can impact fluid and electrolyte balance. Examples include:

  • Dehydration in working dogs can be affected by diet effects on metabolism
  • Brachycephalic syndrome (breed-specific heat stress due to inefficient respiration)
  • Vomiting/diarrhea
  • Trauma/blood loss
  • Kidney disease
  • Endocrine disease

For these and other conditions, special consideration is merited, and a veterinarian should be consulted before using products that could affect fluid and electrolyte status.

All dogs need adequate water to survive, and in most cases, water absorption is enhanced with the addition of sugar, amino acids, and electrolytes. While plain water can address hydration needs, evidence suggests that dogs drink more total water when offered an oral electrolyte solution in addition to plain water. Happy hydrating!