26 Labora/ory Animals (1993) 27, 26-29

Practical venipuncture techniques for the ferretGLEN OTTO*, WILLIAM D. ROSENBLAD & JAMES G. FOX

Division of Comparative Medicine, Massachusetts Institute of Technology, Cambridge, MA 02139, USA

SummaryAs the number of ferrets (Mustela putorius Juro )used in research and kept as pets continues torise, so does the need for simple, humaneresearch and diagnostic techniques. We havedeveloped venipuncture methods for the ferretutilizing the jugular and cephalic veins. Usingthese methods it is possible to repeatedly samplemoderate volumes of blood and to perform intra-venous injections in both conscious and sedatedferrets.

Keywords: Ferret; Venipuncture; Bleedingmethods

Ferrets continue to grow in popularity as researchanimals and as pets, and as a result there is anincreasing demand upon veterinarians and techni-cians to obtain venous blood samples and/orestablish venous access. It has been previouslyreported that the superficial veins of the ferretare not satisfactory for routine venipuncture(Williams, 1976; Fox, 1988) or that anaesthesiais necessary to utilize them (Bleakley, 1980). Forthese reasons, a number of ferret bleeding techni-ques have been detailed in the literature. Cardiacpuncture (Fox, 1988), retro-orbital bleeding (Foxet 01., 1984), and the use of surgically-implantedcatheters (Greener & Gilles, 1985; Mesina et al.,1988) are useful under special circumstances butare too invasive for routine use. Although thetail bleeding technique (Bleakley, 1980; Curl &Curl, 1985) is adequate for obtaining small

'Present address: Animal Resources Center, Committee onComparative Medicine and Pathology, University of Chicago,Chicago IL 60637, USA.

Received 17 December /991; accepted 22 May 1992

volumes of blood under some circumstances,we have found the results to be too variable torely upon it for obtaining samples crucial to adiagnostic workup or research protocol. Collect-ing blood from a clipped toenail (Ryland et al.,1983) or punctured foot-pad (Andrews, 1987) isalso less than optimal since the resulting sampleis often poor in terms of both quantity andquality. Recently, some reports have mentionedjugular venipuncture but no description of thetechnique was given (Ryland et 01., 1983; Moodyet 01. 1985; Andrews, 1987; Randolph, 1989;Heard et al., 1990). Jugular venipuncture (forblood sampling) and cephalic venipuncture (forintravascular administration) are the methods ofchoice in dogs and cats. The purpose of thisreport is to describe similar techniques which wehave developed for use in the ferret.

Materials and methodsAnimalsAdult ferrets (Mustela putorius Jura) used toestablish these techniques were purchased andmanipulated as part of research protocols previ-ously approved by the institutional animal careand use committee. Animals were housed singlyor in compatible pairs in stainless steel cages andwere maintained in compliance with the standardsof the American Association for Accreditationof Laboratory Animal Care. A commercial catdiet (Purina Cat Chow, Ralston Purina Co., $tLouis, MO, USA) was fed once a day andanimals were given water ad libitum.

Cephalic venipunctureThe cephalic vein is readily utilized for intra-venous injections and for the placement of intra-venous catheters. We have adapted a techniquepreviously described for use in the hamster

Ferret venipuncture

Fig. 1. Cephalic venipuncture in the ferret.

(Ransom, 1984). An assistant firmly grasps theneck scruff of the ferret with one hand and therear legs with the other, holding the animalextended in a vertical position. Ferrets oftenremain immobile when held in this manner,possibly due to an instinctual reaction to a'dominant' grip. A quick release tourniquet(fashioned from a piece of rubber band and anaJIigator clip or bulldog clamp) is applied abovethe elbow to distend the vein. For single low-volume intravenous injections, a 25 gauge needleis advanced through the skin and into the vesselwhile slight negative pressure is maintained withthe syringe (Fig. 1). When blood is visualizedin the hub of the needle, one hand is used to holdthe leg and steady the syringe while the otherreleases the tourniquet prior to injection. Forintermittent injections or sustained infusions, a22 gauge indwelling catheter is placed in a similarfashion. Ferret skin is dense, and it may benecessary to carefully pierce the skin overlyingthe vessel with a 20 gauge needle prior to theplacement of an over-the-needle type catheter inorder to avoid catheter buckling.

Jugular venipunctureManual restraint using a towel-wrapping techni-que is adequate to successfully bleed the majorityof ferrets. The animal is firmly but carefullygrasped around the anterior thorax and suspendedin a vertical position. The forelegs of the ferretare extended down along its body and held in this

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Fig. 2. The neck of a shaved ferret. The dotted lines indicatethe position of the external jugular veins.

position while a towel is tightly wound aroundthe animal 3 or 4 times in a manner which leavesthe head and neck uncovered. Venipuncture isperformed with the wrapped animal lying on atable in dorsal recumbency with an assistantrestraining and positioning the head of theanimal as necessary. The external jugular veinsof the ferret are relatively superficial and whendistended they can be seen to extend cranio-laterally from the midline at the thoracic inlet toa point just below the base of the ears (Fig. 2).Venipuncture is most successful if the neck ofthe animal is supported by the last three fingersof one hand while the vein is occluded with thethumb. The index finger is then used to 'milk'blood down the vein and occlude it above thepoint of venipuncture (Fig. 3). This will resultin full distension of the vein, greatly increasingthe probability of successful venipuncture. Theskin is stretched taut between the thumb andindex finger in order to minimize the tendencyof the vessel to roll. Blood is drawn with asyringe tipped with a 20, 22 or 23 gauge I in.needle bent at an approximate 300 angle. Theneedle is first advanced through the relativelytough skin of the ferret at a point slightly lateral

'111//1

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.'ig. 3. The vein is occluded both above and below the pointof needle insertion. The distended vein has been movedmedially and immobilized by applying tension on the

overlying skin.

Fig. 4. A conscious, towel-wrapped ferret being bled via thejugular vein. The animal is being distracted by placing a small

amount of Nutri-cal(!) paste on its nose.

to the vein, and then is redirected in order topierce the vessel. A slight 'pop' may be felt asthe distended vessel is entered by the needle.

This method has allowed us to obtain singleblood samples of up to 8 ml from large maleadults. As in other species, a maximum of 10-15070of blood volume should be withdrawn at anyonetime. Repeated sampling of smaller volumes overshort periods is possible if both jugular veins are

Otto, Rosenblad& Fox

used and haematoma formation is minimized byusing a 23 gauge needle and applying carefuldigital pressure for haemostasis. It has beensuggested that cumulative blood collection shouldnot exceed 20% of total blood volume within any2 week period (Fox, 1984). In those cases wherethe animal does not need to be maintained in afasting state after blood withdrawal, we havefound it useful to distract the animal by offeringit a small amount of a commercially availablenutritional supplement paste (Nutri-cal®; Evsco,Buena, NJ, USA) during bleeding (Fig. 3).Jugular venipuncture is generally performed withone person bleeding and another assisting withrestraint. However, during serial samplinganimals become acclimatized to the procedureand under these circumstances it is often possiblefor one person to bleed the animal with noassistance. As an alternative to manual methodsof restraint, chemical restraint may be used if it isnot contraindicated by the test being performedor the health status of the animal. A combinationof ketamine (30 mg/kg 1M) and acepromazine(0' 3 mg/kg 1M) has proven to be safe andefficacious for jugular bleeding.

DiscussionUsing these methods, it is possible to obtainblood for routine diagnostic procedures, toperform protocols involving repeated bloodsampling, and to administer intravenous therapyin much the same way as one would when dealingwith a dog or cat. The techniques are relativelysimple and can be easily mastered, especially bythose who have prior experience in small animalvenipuncture.

AcknowledgmentThis work was supported in part by Public HealthService grants RROI046 and T32-RR07036 fromthe Division of Research Resources, NationalInstitutes of Health, USA.

Ferret venipuncture

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