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Does plasma volume expand after orally administered steroids in cats

Block CL, Oyama MA. Echocardiographic and biomarker evidence of plasma volume expansion after short-term steroids administered orally in cats. J Vet Intern Med [Internet]. 2019 Dec 9 

An association has long been observed between the administration of steroids and the development of congestive heart failure. In both dogs and humans, administration of steroids has been associated with diastolic dysfunction, and in cats intramuscular steroids have been shown to increase plasma volumes. The purpose of this study was to determine if a short course of oral prednisolone led to detectable changes in BNP or echocardiographic parameters in domestic cats.

The study was designed as a prospective uncontrolled clinical trial of cats presenting to a private specialty hospital and prescribed oral steroids by the attending clinician. Cats were excluded for any disease that may affect BNP (ie hyperthyroidism, hypertension, IRIS III or higher CKD, use of diuretics ACEIs, or fluid therapy, or use of steroids in the previous 2 weeks.

Baseline values measured included signalment and presenting complaint, weight, cardiac auscultation, blood pressure, PCV/TS/BG, BUN/Creat, TT4, nt-proBNP, and echocardiogram with concurrent ECG. Steroid therapy was initiated for 5-7 days, followed by repeat measurement of the above values.

10 cats were recruited and all completed the study, with a median age of 9.5 years. Eight cats had no evidence of cardiac disease on echo and normal BNP values. One cat had 4 chamber dilation and complete AV block, while another had hypertrophic obstructive cardiomyopathy and markedly elevated BNP. One cat was treated with budesonide, while the remainder received prednisolone (median 2mg/kg/day).

While there was no significant change in BNP after administration of steroids, 60% of cats had an increase in BNP >60%, and 38% of cats with a baseline BNP <100 increased to >100 after therapy. A significant increase in total solids was observed.

The LVIDd, LVIDs, LA dimension, LA/Ao ratio, LA area, and left auricular area all significantly increased after therapy.

These findings support the hypothesis that steroid administration is associated with an increase in plasma volume. The authors posit that hyperglycemia is an unlikely cause of this as there was no change in BG, and that a mineralocorticoid effect is more likely. Further work into investigating the effects of drugs such as dexamethasone (which has very little mineralocorticoid activity) may help to elucidate this further.

While it is unlikely that steroid administration causes the development of de novo heart disease, it is likely that changes in plasma volume, atrial and ventricular size, and potentially increased myocardial stretch (as evidenced by BNP changes) may result in a cat with pre-clinical heart disease progressing to CHF. While further work in larger sample sizes and different steroids is indicated, this suggests that even short courses of oral steroids in cats may alter cardiac parameters. (MRK)

See also:

Ployngam T, Tobias AH, Smith SA, Torres SMF, Ross SJ. Hemodynamic effects of methylprednisolone acetate administration in cats. Am J Vet Res. 2006;67(4):583-587.


Khelik IA, Berger DJ, Ward. JL, et al. Clinicopathologic, hemodynamic, and echocardiographic effects of short-term oral administration of anti-inflammatory doses of prednisolone to systemically normal cats. Am J Vet Res.  2019 Aug;80(8):743-755.