Rethink Hydration: Don’t let fluid and electrolytes become the forgotten nutrients this Christmas

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No matter how many awareness campaigns we run, the festive period remains a time of year when veterinary teams expect to be dealing with a higher volume of dietary indiscretions, toxic food ingestion, and general gastrointestinal (GI) disturbances. Whilst in severe cases we are automatically focused on emergent toxin neutralisation and stabilisation, when it comes to those with mild to moderate GI issues that are not considered at immediate risk of significant dehydration, the most overlooked aspect of treatment is often that of fluid and electrolyte balance. Yet clinicians can benefit significantly by learning to ‘rethink hydration’ and including the likelihood of potential dehydration in all clinical assessments. 

Water and electrolytes: vital for life 

Water makes up approximately 60-65% of the bodyweight of all mammals, with fluid homeostasis intrinsically linked to movement of electrolytes. In healthy animals electrolytes dynamically shift between intracellular and extracellular compartments with water osmotically following to maintain equilibrium (Wellman, DiBartola & Kohn, 2016), a process that is essential for the normal functioning of all cells, tissues, and organs. It is no surprise then that even minor electrolyte disturbances can lead to dehydration with subsequent impairment of normal cellular functions.

In humans, studies have shown us that cognitive dysfunction and fatigue can occur with as little as 2% dehydration, yet in dogs and cats, dehydration of <5% is often not detectable from clinical exam alone (Tello & Perez-Freytes, 2017). 

Rethink Hydration, this festive season 

We expect most acute gastrointestinal cases we see over the festive period to resolve with supportive therapy delivered on an ‘out-patient’ basis. Treatment plans often incorporate analgesics, antiemetics, nutraceuticals, gastro-protectants, and dietary modifications. Without active signs of clinical dehydration however, fluid and electrolyte requirements may not always be accurately perceived. And yet acute decompensation, as a result of significant hypovolemia and acid-base disturbances, remains an ever-present risk in these cases. Occurring secondary to hypersecretory stimulation of electrolyte transport channels in enterocytes or increased faecal solute load; both resulting in hyperosmotic water losses into the intestinal lumen
(Silverstein & Hopper, 2015).

In dogs and cats 99% of all fluid ingested is absorbed via the gastrointestinal tract meaning any damage to the intestinal epithelium, or disruption of intestinal electrolyte secretory and absorptive mechanisms, can rapidly lead to dehydration (Silverstein & Hopper, 2015). Therefore, as veterinary professionals we need to ‘rethink hydration’ and not just base treatment plans on perceived current clinical status but consider proactive management anytime there is anticipated increased fluid losses or decreased fluid intake. Examples of this would include decreased appetite, vomiting, diarrhoea, polyuria, increased panting, or supressed thirst mechanisms (as found in very young and older animals).

Oral Rehydration Therapy: the proactive choice

Oral Rehydration Therapy (ORT) using Oral Rehydration Solutions (such as Oralade®, Macahl Animal Health) represents the most physiologic way to provide water and electrolytes to correct dehydration. In cases of mild to moderate dehydration, using appropriate ORT has been shown to be as effective as intra-venous fluid therapy (IVFT) for managing fluid and electrolyte losses in several common clinical scenarios, including haemorrhagic diarrhoea in dogs (Reineke, Walton & Otto, 2013). In fact, ORT is considered inappropriate as the sole source of hydration only in cases of hypovolaemic shock, severe and persistent vomiting (at least 25% of the hourly oral requirement), or if the volume of stool losses cannot match oral intake (Reineke, Walton & Otto, 2013). Compared to IVFT, ORT offers cost savings, easier administration that requires no special training or equipment, and no risks of complications such as phlebitis or overhydration. 

Prevention is better than cure and therefore the management of any condition or situation that creates fluid losses or disturbance to fluid metabolism should include a proactive oral hydration strategy.

Dr Gemma Davidson BVSc MRCVS

Gemma qualified from the University of Liverpool in 2010. Having spent 5 years in small animal practice, she moved into the veterinary nutraceutical industry in 2015 and is now Veterinary Technical Manager at Macahl Animal Health

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Reineke, E., Walton, K. and Otto, C., (2013). Evaluation of an oral electrolyte solution for treatment of mild to moderate dehydration in dogs with hemorrhagic diarrhea. Journal of the American Veterinary Medical Association, 243(6), pp.851-857.

Silverstein, D. and Hopper, K., (2015). Small animal critical care medicine. 2nd ed. St. Louis, Mo.: Saunders/Elsevier, pp.622-626.

Tello, L. and Perez-Freytes, R., (2017). Fluid and Electrolyte Therapy During Vomiting and Diarrhea. Veterinary Clinics of North America: Small Animal Practice, 47(2), pp.505-519.

Wellman, M., DiBartola, S. and Kohn, C., (2016). Applied Physiology of Body Fluids in Dogs and Cats. [online] Veterian Key. Available at: [Accessed 10 December 2021].


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