# Comparing Blood Sampling Techniques in Canines: A Pilot Study Using Oclacitinib

## TL;DR

This study compared two blood sampling methods in dogs and found that using a catheter reduces stress without affecting drug measurement accuracy.

## Contribution

The study provides evidence that catheter-based blood collection is less stressful for dogs while maintaining reliable pharmacokinetic data.

## Key findings

- Both blood collection methods produced similar drug concentration measurements.
- Catheter use showed a trend of lower cortisol levels, indicating reduced stress in dogs.
- Catheter-based sampling is recommended for less invasive and welfare-friendly procedures in drug development.

## Abstract

This study aimed to identify whether different blood sampling methods affect the measurements of drug levels and stress in dogs. For this, the dogs were treated with a drug called Apoquel, a drug commonly used for treating allergic skin diseases in dogs. Two techniques, namely, direct needle draws from a major vein in the neck and collections through a preplaced forearm catheter were compared. With the final four dog participants in the study, blood samples were taken at regular intervals for six hours to track the movement of the drug and measure the stress hormone levels, cortisol. Results showed that both the blood collection methods were equally reliable, but the use of the catheter tended to reduce the stress associated with blood collection. The study highlights how small changes in medical procedures can improve animal welfare without compromising data quality, benefiting both pets and veterinary care standards.

Pharmacokinetic studies are critical to assess drug absorption, distribution, metabolism, and excretion in companion animals. Blood collection methods such as direct venepuncture or indwelling catheters could influence pharmacokinetic outcomes and animal welfare. A direct comparison of drug concentrations of two blood sampling methods was investigated in this study to identify any potential differences and their impact on animal welfare. Four canines (male = 3, female = 1) were treated with Apoquel® (oclacitinib 0.4–0.6 mg/kg) and blood samples were obtained via direct venepuncture into the jugular and a cephalically placed catheter. The drug distribution and cortisol concentration were examined over several time points (0.25, 0.5, 1, 2, 4, and 6 h post treatment). Statistical analysis revealed no significant differences (p > 0.05) in the concentration of the drug between the two collection methods, indicating that both methods are acceptable in generating reliable results for pharmacokinetic data. Nevertheless, cortisol levels indicated a trend suggesting catheter collection may be associated with reduced stress compared to direct venepuncture (Catheter = 201 ± 91; Direct venepuncture = 208 ± 96. This study provides evidence to use a less invasive blood collection such as via a catheter during intensive bleeding schedules that are required in early drug development, thereby improving the overall welfare for the animal.