This cat is 6-7% dehydrated, hallmarked by dry mucous membranes and reduced skin turgor, but normal cardiovascular parameters. An appropriate fluid rate is 20 ml/h. This accounts for both her maintenance fluid needs (40 ml/kg/d x 4.4 kg = 176 ml/day or 7.3 ml/h) and a 7% dehydration deficit.
Recall the formula to calculate dehydration deficit:
% dehydration (expressed as a decimal) x body weight in kgs = L fluid needed
Therefore, to correct the dehydration deficit:
0.07 x 4.4 kg = 0.308 L
0.308 L x 1000 ml/L = 308 mls
308 mls/24 h = 12.8 ml/h
7.3 ml/h (maintenance) + 12.8 ml/h (dehydration deficit) = 20.1 ml/h
Fluid therapy is rarely cut and dry and veterinary medicine evolves: some resources cite multiplying by a correction factor of 0.6 to account for total body water, while others do not. The biggest mistake made in creating a fluid plan is infrequent reassessment and adjustment! As bloodwork becomes available, and you monitor the cat’s response to fluids, you can adjust your fluid plan.
Assess the cat every four to eight hours using a combination of physical exam/vital parameters, blood pressure, and PCV/TS. Keeping a cat on a high rate of fluids without adjusting to the patient’s needs may lead to fluid overload, hypoalbuminemia, anemia, and coagulopathy.
Account for ongoing losses through vomiting, regurgitation, and diarrhea, and add this to the fluid plan if appropriate. Do not wait for completed diagnostics before starting this cat on IV fluids, because in that time period, her dehydration could progress and she could develop shock.
