Blood Collection Techniques in Exotic Small Mammals Janis Ott Joslin, DVM

Topics in Medicine and Surgery Blood Collection Techniques in Exotic Small Mammals Janis Ott Joslin, DVM Abstract Blood collection from small exotic pocket pets can be difficult to achieve. The individual collecting the blood must know both the anatomy and behavior of the species to obtain suitable amounts of blood for diagnostic testing. Given the animals’ small size, it is often difficult to collect large volumes of blood. A clinician serious in developing an exotic small mammal practice should understand the limitations of blood sample collection and the risks involved with the procedure. Unlike domestic animals, these pets are often not comfortable with being handled and are often prone to induced complications when presented to a veterinary clinic and restrained for examination. For some cases, the clinician will have to determine if the risk of getting the sample is better achieved by anesthetizing the patient, and if doing so will have a detrimental effect on the animal. One will also need to consider the effect of the anesthetic versus the stress the restraint may have on the blood results. Copyright 2009 Elsevier Inc. All rights reserved. Key words: blood collection; exotic small mammal; ferret; rabbit; rodent; venipuncture he size of many small exotic pocket pets seen when handled, anesthetized, or transported. Fur- in private veterinary practices can make diag- thermore, while at the veterinary clinic, these ani- Tnostic blood sample collection problematic. mals are often exposed to bright lights and loud It is often difficult to access veins or arteries of noises and can hear, smell, and see predators such as adequate size to collect sufficient blood for diagnos- dogs and cats which are disturbing to these often tic testing. However, with the advent of in-house nocturnal and crepuscular species. If one can mini- analyzers that can measure hematologic and blood mize or eliminate the effect that outside stressors chemistry parameters from small volumes of whole have on these animals, they can reduce these effects ␮ blood (50-100 L; 0.05-0.1 mL), it is now possible to on stress-sensitive blood parameters. pursue diagnostic blood work on many of these exotic small mammals. Western University of Health Sciences, College of Veterinary Minimizing the Effects of Stress and Medicine, Pomona, CA USA. Other Effects on Blood Results Address correspondence to: Janis Ott Joslin, DVM, Professor, Zoo and Wildlife Medicine, Western University of Health Sciences, College of Veterinary Medicine, 309 East 2nd St, Pomona, CA The majority of the small exotic mammals that 91766. E-mail: [email protected]. present to veterinary clinics are prey species by na- © 2009 Elsevier Inc. All rights reserved. ture, with the ferret (Mustela putorius furo) being an 1557-5063/09/1802-$30.00 exception. Therefore, these animals are easily stressed doi:10.1053/j.jepm.2009.04.002 Journal of Exotic Pet Medicine, Vol 18, No 2 (April), 2009: pp 117–139 117 118 Ott Joslin Understanding the animal’s natural behavior and tion the rat for the procedure by putting treats in a making appropriate accommodations is also helpful similar syringe case. when collecting blood samples from exotic small There is evidence that the stress of anesthetic mammals. For species such as sugar gliders (Petaurus induction can have an effect on blood values in breviceps), which are mainly nocturnal, it is preferable laboratory animals. For example, ferrets anesthe- to schedule the examinations early in the morning tized with isoflurane (Forane; Baxter Health Care when they are less active and when the clinic is quiet. Corporation, Deerfield, IL USA) exhibit a rapid de- However, if you want to observe the same animal’s crease in their hematocrit, hemoglobin, and red activity levels, the appointment should be scheduled blood cell count, and these hematologic values do in the early evening when they are more active. On not return to preanesthetic levels until 45 minutes arrival at the clinic, these animals should be brought after the initiation of the procedure.3 The clinician directly into a warm (70-72°F, 21-22°C) examination must therefore consider the effect that anesthesia room with subdued lighting, away from other dis- has on laboratory data and the risk of the anesthesia turbing sights, sounds, and smells that are associated on an ill ferret. It is ultimately the veterinarian’s with veterinary hospitals.1 responsibility to determine the benefits and risks of For those small exotic mammals that are used to using anesthesia for these animals when collecting being handled, blood collection can be done quickly blood for diagnostic testing. with minimal restraint. Ideally, the owner should Many of the blood collection sites and sampling transport the animal to the clinic in its own cage, techniques used for small exotic mammals are simi- covered with a towel so that it is in a darkened lar to those described for cats and dogs. However, for enclosure. The animal should be removed from its some of the blood collection sites, such as the cranial cage for venipuncture and then returned to its cage vena cava, an inexperienced handler and phleboto- rather than being put into an unfamiliar enclosure. mist would benefit from anesthetizing the patient For animals that are not easily restrained, anesthesia until the necessary skills are acquired to perform the is recommended to facilitate sample collection. Tra- procedure on an alert animal. Doing so reduces the ditionally, small exotic, pocket pets have been bled stress on the animal, the owner, and the veterinary using manual restraint but the author believes that personnel performing the procedure. in the majority of the cases anesthesia is indicated in There are a number of other physiologic and these animals. The author prefers to anesthetize the environmental factors that can affect hematologic animal in its cage before handling and then return it test results, including gender, age, strain, circadian directly to its cage to recover. rhythms, stage of reproductive cycle, pregnancy, Conditioning an animal before sample collection diet, and season (e.g., animals that hibernate such as can reduce the potential effects of stress on the a hamster). Laboratory processing (e.g., type of an- results. A study by Fluttert and coworkers1 demon- ticoagulant used) and venipuncture site can also 4 strated that rats handled for 2 minutes for 4 to 5 days affect the blood test results. It is important for cli- before blood collection produced levels of plasma nicians to consider the potential effects of these corticosterone 8 to 10 times lower than those in rats factors when interpreting test results. Ideally, if one’s not preconditioned. Furthermore, corticosterone practice has a large enough small exotic mammal caseload, then in-house reference ranges can be de- levels in the nonpreconditioned rats did not return veloped, but this requires one to follow a consistent to normal until 120 minutes later.2 The precondi- methodology when collecting blood samples includ- tioning of the rats consisted of placing the rat in a ing the use of anesthesia, type of anesthetic agent, towel, loosely folded around the animal, for 2 min- and form of anticoagulant. utes, thereby allowing the subject to explore the “tunnel.”2 The rat’s tail was stroked and gently squeezed to simulate the blood collection. After the Basic Restraint and Anesthesia for preconditioning period, the blood sample was col- Blood Collection lected.2 This type of preconditioning can easily be done by the pet’s owner before it is brought to the Basic handling and anesthetic protocols for small clinic. The towel used to handle the animal during exotic mammals have been well covered in several preconditioning can be used for the blood collec- recent articles1,5-10 and books,11-13 and thus will not tion, because it will have the animal’s scent on it and be covered in this article. Specific restraint proce- should minimize the stress level of the patient. If a dures for handling of small exotic mammals for syringe case with holes in the end is used for re- collecting blood from sites unique to these patients straint, the owner should be instructed to precondi- will be described. Blood Collection in Small Mammals 119 Total Blood Volume and Recommended Table 2. Relationship between total Maximum Blood Sample Size blood volume (mL) and whole blood volume as a percentage of body weight The total volume of blood that can be safely col- 13 lected from small exotic mammals for blood analysis (%) as weight increases in rats should be based on the size of the animal being bled. Total Blood Whole Blood Volume A standard of collecting 1% of the animal’s lean Volume as a Percentage of body weight is often given as the best estimate for a Body Weight (g) (mL) Body Weight (%) safe sample volume; however, there are a number of 250 17.4 6.97 cases where sampling at this volume is not recom- 300 19.5 6.51 mended. For example, it is generally recommended 350 21.1 6.04 that smaller volumes of blood be collected for pa- 400 22.3 5.58 tients that are geriatric or suspected of being anemic or hypoproteinemic. It is important for the veterinarian to consider the potential negative effects of collecting too much blood from a compromised or obese patient. The most accurate techniques use sodium radio- Ideally, the amount of blood collected from a chromate or sodium pertechtate as a red cell label to patient should be based on published data of the determine red cell volume, and human serum la- total blood volume of a given species. However, be- beled with radioiodine as a plasma label to measure 14 fore using the published figures, one needs to know plasma volume.

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