Source: Kay Stewart, RVT, RLATG, CMAR; Valerie A. Schroeder, RVT, RLATG. University of Notre Dame, IN

The collection of blood from mice and rats for analysis can be done through a variety of methods. Each method of collection has variations in the type of restraint required, the invasiveness of the procedure, and the necessity of a general anesthetic.¹Historically, the use of the retro-orbital sinus cavity has been used, but not without debate. The controversy related to the potential tissue damage,or even blindness,caused by retro-orbital bleeds has led to the development of facial and submandibular vein bleeding methods in mice.Blood collection from the saphenous vein in both mice and rats is another technique that has been developed. These procedures do not require anesthesia and therefore are suitable when the use of anesthetics may confound blood results or other data.

1. Facial vein bleed in mice

1. Equipment
   1. Collection of blood is from a free catch into a blood tube or an Eppendorf tube. In some cases, it is desirable to collect blood directly into hematocrit tubes.
   2. Goldenrod lancets will be selected based on the appropriate size for the animal according to age and sex.
      1. Lancets are selected according to the age/size of mice as follows:
         4mm lancet: 3-4-week-old mice (under 15 grams body weight)
         5mm lancet: female mice und

The method of blood collection can cause a variation in the analysis of the sample. The skill level of the technician performing the sample collection has an impact on the quality of the sample and the welfare of the animal. The use of anesthetics can also affect the sample quality. The methods described here are all performed without the use of anesthesia, thus that variable has been eliminated. Also, all of these techniques can be used for serial sampling with minimal discomfort to the animal.