Submitted by: Patricia Shea, DVM
J Am Vet Med Assoc 2023;261:104-110
Oil-based compounding flavors more accepted by feline patients
Nichelason AE, Schultz KK, et al.
The use of compounded medications is a cornerstone of feline practice. Getting cats to take pills or capsules is notoriously difficult and often ends in damage to the human-animal bond and little to no compliance with treatment. The use of oral liquid medications in lieu of solid formulations is generally considered to be easier in cats and therefore more “cat friendly.”
In this study of 46 healthy cats between 1 and 12 years of age, the investigators evaluated the animals’ voluntary acceptance of 10 commercially available compounding flavors used in formulating liquid medications for cats. The flavors were selected on the basis of results of previous studies of flavor preferences in cats, as well as the routine availability of certain flavors in compounding pharmacies. None of the study cats had received any oral medications in the six months prior to the study. Some of the flavors were oil-based: grilled chicken, natural, oil miscible; fish, artificial, liquid, oil-miscible; and liver, artificial, liquid, oil-miscible. The remaining flavors were water-based: liver, liquid, water-miscible; chicken pot pie; grilled tuna; marshmallow, artificial; and vanilla butternut, artificial. Identical flavors were not available to make both oil and water formulations, so similar flavors for both formulations in liver, chicken, and fish were selected.
Two control flavors, one oil-based and one water-based completed the available flavor selection. These represented the base (vehicle) for the other eight compounding flavors. The oil-based vehicle was a fixed oil suspension, while the water-based vehicle was Ora-Blend (Perrigo Company plc). Ora-Blend contains two sweeteners: sucrose and sorbitol, and has a citrus-berry flavoring. All of the compounding flavors had a pH of 4 to 4.5.
Each participating owner received a kit with each of the 10 flavors. Owners were asked to tell the investigators which of the flavors they predicted their cats would like most and least. The flavoring trials had a duration of 14 days; the first four days were an acclimation period, in which the cat received a high-value treat they liked on a feeding tray provided in the kit. During the remaining 10 days of the trial, the owner placed 5 mL of one of the flavorings, identified by number only, into the feeding tray. Then they would observe the cat’s response to the flavoring and willingness to consume it. The time of removal of the tray after the cat had time to consume it or not was recorded, as well as the owner’s perception of the cat’s response on a 7-point scale (1 = disliked it to 7 = loved it). Trays and syringes containing the liquid not consumed by the cat were returned to the investigators and weighed to calculate the amount of liquid actually consumed by each cat.
All of the study cats had been gonadectomized; there were 25 spayed females and 16 neutered males. Almost ¾ (74.2%) of the individual flavor samples were disliked by the cats (score 1-2); 14.0% of the samples had a moderate preference rating (scores 3-5), and 11.2% (scores 6-7) were well-liked. The flavoring base (oil or water) was the major determinant of whether or not the cats liked the flavoring, with the individual acceptance of oil-based flavors significantly higher than the water-based flavors. However, the cats still did not accept 60% of the oil-based flavor samples. Rejection of the water-based flavor samples was even higher at 85%. The investigators found that the residual weight or volume of a sample after the cat had consumed the amount, they wanted directly correlated with the owner’s evaluation of the cat’s enjoyment of the flavoring. The most accepted flavorings were the oil-based chicken and the oil-based fish. The least-liked flavors were the water-based marshmallow and water-based vanilla butternut. Sweet water-based flavorings were actually less accepted than the other water-based flavors, including the water-based control. Although some studies have reported that cats will accept sucrose and glucose, it is known that cats do not have a sweet receptor gene and are unable to taste sweet flavorings. The fact that the study cats disliked the sweet flavorings more than the water-based control suggests that they actively disliked the marshmallow and vanilla butternut flavors.
No difference in flavor preferences was found between subjects that had previously been given liquid medications (more than six months prior to the commencement of the study) and those that had not. Also, the owners of the cats were not adept at predicting which of the flavors their cats would like, but the cause of this was unclear. The results of the study indicate that when liquid medications are ordered for cats, oil-based flavorings should be selected if possible, and sweet flavorings should be avoided.