We acknowledge the skilful assistance of Annie B. Kristensen, Elisabeth V. Andersen, Belinda B. Bringtoft and the animal caretakers at the Department of Experimental Medicine, Frederiksberg Campus, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark. Jacob L&#248;nholdt is thanked for his excellent technical assistance in filming the procedures. This study was supported in part by the LIFEPHARM Centre for in vivo Pharmacology and University of Copenhagen.

The shown procedures were performed according to protocols approved by the Danish Animal Experimentation Inspectorate under the Ministry of Food, Agriculture and Fisheries.
1. Blood Sampling from the Lateral Saphenous or Tarsal Vein
<ol>
	<li>Perform this procedure without anaesthesia and the help of one investigator, one handling the guinea pig, and one collecting the sample.</li>
	<li>Shave the tarsal region of the hind leg with an electric shaver until the veins are visible. Ensure the area is large enough to avoid fur interfering with the puncture site.</li>
	<li>Place the hind leg in a lukewarm water bath and gently rub the leg, making the veins more dilated and evident.</li>
	<li>Wipe the leg with a clean towel and disinfect the puncture site with gauze or a cotton swab dampened with 70% alcohol.</li>
	<li>Restrain the guinea pig and extend the hind leg downward while applying gentle pressure immediately above the knee joint to provide stasis.</li>
	<li>Puncture the vein using a 21 G needle or lancet. Collect blood e.g., by using a collection or capillary tube. Gently manipulate the leg to aid the blood flow.</li>
	<li>Release stasis, once the sample has been obtained. Apply a piece of gauze or cotton wool with gentle pressure to the puncture site until bleeding has stopped.</li>
	<li>Return the animal to its cage and monitor for 5-10 min to ensure hemostasis.</li>
</ol>
2. Blood Sampling from the Ear Vein
<ol>
	<li>Perform this procedure without anaesthesia either alone or preferably with the help of one colleague.</li>
	<li>Disinfect the dorsal surface of the ear using gauze or a cotton swab dampened with 70% alcohol.</li>
	<li>Apply light pressure to the base of the ear to provide stasis.</li>
	<li>Puncture the vein using a 21 G needle or lancet, and collect blood.</li>
	<li>Release stasis, once the sample has been obtained, Apply a piece of gauze or cotton wool with gentle pressure to the puncture site until bleeding has stopped.</li>
	<li>Return the animal to its cage and monitor for 5-10 min to ensure hemostasis.</li>
</ol>
3. Blood Sampling from the Jugular Vein
<ol>
	<li>Carry out this procedure using the help of one additional investigator; one handling the guinea pig and one collecting the sample.</li>
	<li>Anaesthetize the guinea pig with a suitable anaesthetic for the entire duration of this procedure. A mixture of tiletamine (0.93 mg/kg), zolazepam (0.93 mg/kg), xylazine (1.49 mg/kg) and butorphanol (0.06 mg/kg) can be used.</li>
	<li>Place the anaesthetized guinea pig on its back and gently retract the forelegs caudally.</li>
	<li>Shave and disinfect (e.g., with 70% alcohol) the ventral part of the neck.</li>
	<li>Coat the syringe with either heparin or EDTA prior to sampling in order to reduce risk of clotting.</li>
	<li>Palpate the clavicle and insert a 25 G (or 23 G) needle mounted on a 1 ml syringe approximately 1 cm lateral to the midline at the level of the shoulder joint. Keep the syringe in a slight upward and medial angle while applying a slight negative pressure. Avoid damaging the underlying structures as the jugular vein is situated quite superficial. Tilt the neck of the guinea pig slightly backwards to provide increased stasis of the vein.</li>
	<li>Release the front legs when the blood sample is obtained, and alleviate stasis before the needle is retracted. Use a dry piece of gauze or cotton wool to apply gentle pressure to the puncture site.</li>
	<li>Return the animal to a recovery cage and monitor to ensure hemostasis and recovery from anaesthesia.</li>
</ol>

<ol>
	<li>DeOgburn, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Effects+of+increased+dietary+cholesterol+with+carbohydrate+restriction+on+hepatic+lipid+metabolism+in+Guinea+pigs.">Effects of increased dietary cholesterol with carbohydrate restriction on hepatic lipid metabolism in Guinea pigs.</a> Comp.Med. 62 (2), 109-115 (2012).</li><li>Fernandez, M., Volek, J. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Guinea+pigs+a+suitable+animal+model+to+study+lipoprotein+metabolism,+atherosclerosis+and+inflammation.">Guinea pigs a suitable animal model to study lipoprotein metabolism, atherosclerosis and inflammation.</a> Nutr Metab (Lond). 3 (17), (2006).</li><li>Frikke-Schmidt, H., Tveden-Nyborg, P., Birck, M. M., Lykkesfeldt, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High+dietary+fat+and+cholesterol+exacerbates+chronic+vitamin+C+deficiency+in+guinea+pigs.">High dietary fat and cholesterol exacerbates chronic vitamin C deficiency in guinea pigs.</a> Br J Nutr. 105 (1), 54-61 (2011).</li><li>Hem, A., Smith, A. J., Solberg, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Saphenous+vein+puncture+for+blood+sampling+of+the+mouse,+rat,+hamster,+gerbil,+guinea+pig,+ferret+and+mink.">Saphenous vein puncture for blood sampling of the mouse, rat, hamster, gerbil, guinea pig, ferret and mink.</a> Lab Anim. 32 (4), 364-368 (1998).</li><li>Parasuraman, S., Raveendran, R., Kesavan, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Blood+sample+collection+in+small+laboratory+animals.">Blood sample collection in small laboratory animals.</a> J Pharmacol Pharmacother. 1 (2), 87-93 (2010).</li><li>Guillen, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=FELASA+guidelines+and+recommendations.">FELASA guidelines and recommendations.</a> J Am Assoc Lab Anim Sci. 51 (3), 311-321 (2012).</li><li>Ye, P., Cheah, I. K., Halliwell, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High+fat+diets+and+pathology+in+the+guinea+pig+Atherosclerosis+or+liver+damage.">High fat diets and pathology in the guinea pig Atherosclerosis or liver damage.</a> Biochim Biophys Acta. 1832 (2), 355-364 (2013).</li><li>Tveden-Nyborg, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Maternal+vitamin+C+deficiency+during+pregnancy+persistently+impairs+hippocampal+neurogenesis+in+offspring+of+guinea+pigs.">Maternal vitamin C deficiency during pregnancy persistently impairs hippocampal neurogenesis in offspring of guinea pigs.</a> PLoS One. 7 (10), 12-18391 (2012).</li><li>Schjoldager, J. G., Tveden-Nyborg, P., Lykkesfeldt, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Prolonged+maternal+vitamin+C+deficiency+overrides+preferential+fetal+ascorbate+transport+but+does+not+influence+perinatal+survival+in+guinea+pigs.">Prolonged maternal vitamin C deficiency overrides preferential fetal ascorbate transport but does not influence perinatal survival in guinea pigs.</a> Br J Nutr. 110 (9), 1573-1579 (2013).</li><li>Greulich, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Secretory+products+of+guinea+pig+epicardial+fat+induce+insulin+resistance+and+impair+primary+adult+rat+cardiomyocyte+function.">Secretory products of guinea pig epicardial fat induce insulin resistance and impair primary adult rat cardiomyocyte function.</a> J Cell Mol Med. 15 (11), 2399-2410 (2011).</li><li>Swifka, J., Weiss, J., Addicks, K., Eckel, J., Rosen, P. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Epicardial+fat+from+guinea+pig+a+model+to+study+the+paracrine+network+of+interactions+between+epicardial+fat+and+myocardium.">Epicardial fat from guinea pig a model to study the paracrine network of interactions between epicardial fat and myocardium.</a> Cardiovasc Drugs Ther. 22 (2), 107-114 (2008).</li><li>Pilny, A. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Clinical+hematology+of+rodent+species.">Clinical hematology of rodent species.</a> Vet.Clin North Am Exot Anim Pract. 11 (3), 523-vii (2008).</li><li>Franco, N. H., Olsson, I. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Scientists+and+the+3Rs:+attitudes+to+animal+use+in+biomedical+research+and+the+effect+of+mandatory+training+in+laboratory+animal+science.">Scientists and the 3Rs: attitudes to animal use in biomedical research and the effect of mandatory training in laboratory animal science.</a> Lab Anim. 48 (1), 50-60 (2014).</li><li>Van, L. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=eAssessing+the+application+of+the+3Rs+a+survey+among+animal+welfare+officers+in+The+Netherlands.">eAssessing the application of the 3Rs a survey among animal welfare officers in The Netherlands.</a> Lab Anim. 47 (3), 210-219 (2013).</li><li>Sloan, R. C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=High+doses+of+ketamine-xylazine+anesthesia+reduce+cardiac+ischemia-reperfusion+injury+in+guinea+pigs.">High doses of ketamine-xylazine anesthesia reduce cardiac ischemia-reperfusion injury in guinea pigs.</a> J Am Assoc Lab Anim Sci. 50 (3), 349-354 (2011).</li><li>Jacobson, C. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+novel+anaesthetic+regimen+for+surgical+procedures+in+guinea+pigs.">A novel anaesthetic regimen for surgical procedures in guinea pigs.</a> Lab Anim. 35 (3), 271-276 (2001).</li><li>Saha, J. K., Xia, J., Grondin, J. M., Engle, S. K., Jakubowski, J. A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Acute+hyperglycemia+induced+by+ketamine+xylazine+anesthesia+in+rats+mechanisms+and+implications+for+preclinical+models.">Acute hyperglycemia induced by ketamine xylazine anesthesia in rats mechanisms and implications for preclinical models.</a> Exp Biol Med(Maywood). 230 (10), 777-784 (2005).</li></ol>

The authors have nothing to disclose. All procedures were approved by the Animal Experimentation Act of Denmark, which is in accordance with the Council of Europe Convention ETS 123.

Compared to mice and rats, guinea pigs are fearful by nature and must be approached calmly and handled correctly in order to reduce stress. From an animal welfare point of view, acting with care is naturally a priority; however, this will also reduce the risk of anxiety-associated effects on the collected data e.g., increased blood levels of corticosteroids and glucose12. Likewise, daily handling will habituate the animals to normal procedures and may serve to reduce stress even further. Practical exp...

The guinea pig is a valuable and validated experimental animal model due to a number of biological similarities to humans such as a requirement for a dietary supply of vitamin C, comparable plasma lipoprotein metabolizing enzymes and lipoprotein profiles, as well as shared similarities with human placentation and prenatal development1-3,7,8. This makes the guinea pig an attractive and suitable model for studying effects of diet-associated diseases such as non-alcoholic fatty liver disease, cardiovascular diseases and putative effects of vitamin C deficiency but also the effect of e.g., maternal dietary intervention on the developing offspring.
Repeated blood sampling is often required in both long and short term in vivo studies. Due to species-specific anatomical differences modulation of the sampling technique is necessary in order to obtain blood samples in guinea pigs compared to other rodent models4,5. This includes variation in the course of veins and arteries, and also that guinea pigs do not have a tail, thus have different requirements and options for both sampling and handling. Sampling from the saphenous or tarsal vein, induces minimal discomfort and stress in the animal and does not require anaesthesia3,9. This technique allows repeated samples of small amounts of blood (100-400 &#181;l), e.g., to determine biochemical markers in plasma. If an even smaller sample size is sufficient (50-100 &#181;l), this can quite easily be obtained by puncturing the ear vein. This technique can also be carried out in conscious animals and is useful for example when measuring blood glucose10,11. Sampling from the jugular vein allows for collection of larger amounts of blood (1-2 ml) but requires anaesthesia.
Here, we present four different blood sampling techniques for either conscious or anaesthetized guinea pigs. The procedures are all non-terminal procedures provided that sample volumes and number of samples do not exceed guidelines for blood collection in laboratory animals6. It is in the interests of good science as well as of animal welfare that stress should be kept to a minimum. Consequently, only well-trained and competent personal should perform the animal procedures.

<table><tbody><tr><td>Electric shaver</td><td>Wella (Contura), Denmark</td><td>273207</td><td>Alternative product may be used. Multiple suppliers</td></tr><tr><td>Syringes&amp;nbsp;</td><td>B.Braun-Omnifix-F, Germany</td><td>9161406V</td><td>Alternative product may be used. Multiple suppliers</td></tr><tr><td>Needles</td><td>BD Microlance, Spain</td><td>301156</td><td>Alternative product may be used. Multiple suppliers</td></tr><tr><td>Microvette collection tube&amp;nbsp;</td><td>Sarstedt, D-51588N&amp;uuml;mbrecht, Germany</td><td>201,288,100</td><td>Alternative product may be used. Multiple suppliers</td></tr><tr><td>Accu-Check analyzer</td><td>Roche A/S Diagnostics, Denmark</td><td></td><td>Alternative product may be used. Multiple suppliers</td></tr><tr><td>Heparin 5000 IE/ml</td><td>LEO Pharma, Denmark</td><td></td><td>Alternative product may be used. Multiple suppliers</td></tr><tr><td>Anesthesia</td><td>Zoletil 50, Chemvet, Denmark</td><td></td><td>Alternative product may be used. Multiple suppliers</td></tr><tr><td>Anesthesia</td><td>Narcoxyl vet 20 mg/ml, Intervet, Denmark</td><td></td><td>Alternative product may be used. Multiple suppliers</td></tr><tr><td>Anesthesia</td><td>Torbugesic vet 10 mg/ml, Scanvet, Denmark</td><td></td><td>Alternative product may be used. Multiple suppliers</td></tr><tr><td>Neutral eye ointment</td><td></td><td></td><td>Alternative product may be used. Multiple suppliers</td></tr><tr><td>Gauze or a cotton swab&amp;nbsp;</td><td></td><td></td><td>Alternative product may be used. Multiple suppliers</td></tr><tr><td>Disinfectant (70% alcohol)</td><td></td><td></td><td>Alternative product may be used. Multiple suppliers</td></tr></tbody></table>

non-terminal blood sampling techniques in guinea pigs

Guinea pigs possess several biological similarities to humans and are validated experimental animal models1-3. However, the use of guinea pigs currently represents a relatively narrow area of research and descriptive data on specific methodology is correspondingly scarce. The anatomical features of guinea pigs are slightly different from other rodent models, hence modulation of sampling techniques to accommodate for species-specific differences, e.g., compared to mice and rats, are necessary to obtain sufficient and high quality samples. As both long and short term in vivo studies often require repeated blood sampling the choice of technique should be well considered in order to reduce stress and discomfort in the animals but also to ensure survival as well as compliance with requirements of sample size and accessibility. Venous blood samples can be obtained at a number of sites in guinea pigs e.g., the saphenous and jugular veins, each technique containing both advantages and disadvantages4,5. Here, we present four different blood sampling techniques for either conscious or anaesthetized guinea pigs. The procedures are all non-terminal procedures provided that sample volumes and number of samples do not exceed guidelines for blood collection in laboratory animals6. All the described methods have been thoroughly tested and applied for repeated in vivo blood sampling in studies within our research facility.

Four different approaches to non-terminal in vivo blood sampling techniques in either conscious or anaesthetized guinea pigs have been presented. Figure 1 illustrates the course of the lateral saphenous and tarsal vein in the guinea pig and possible puncture sites. Ear veins visible on the dorsal surface of a guinea pig ear are illustrated in Figure 2. These veins can be used for blood sampling when only a very small volume is required. The position of the guinea pig for jugular...

Watch this Scientific Journal Video about Non-Terminal Blood Sampling Techniques in Guinea Pigs at JoVE.com

Non-Terminal Blood Sampling Techniques in Guinea Pigs

Though a known model, the guinea pig currently represents a niche in experimental animal sciences and limited data is available on the execution of most procedures. Here we present four different approaches to non-terminal in vivo blood sampling techniques in either conscious or anaesthetized guinea pigs.

Guinea pigs possess several biological similarities to humans and are validated experimental animal models1-3. However, the use of guinea pigs currently ...

non-terminal-blood-sampling-techniques-in-guinea-pigs

Research

JoVE Journal

Biology

37.4K Views.  University of Copenhagen. Though a known model, the guinea pig currently represents a niche in experimental animal sciences and limited data is available on the execution of most procedures. Here we present four different approaches to non-terminal in vivo blood sampling techniques in either conscious or anaesthetized guinea pigs. 

Video: Non-Terminal Blood Sampling Techniques in Guinea Pigs

Drawing Blood from Rats through the Saphenous Vein and by Cardiac Puncture

Drawing blood from rodents is necessary for a large number of both in vitro and in vivo studies. Sites of blood draws are numerous in rodents: retro-orbital sinus, jugular vein, maxillary vein, saphenous vein, heart. Each technique has its advantages and disadvantages, and some are not approved any more in some countries (e.g., retro-orbital draws in Holland). A discussion of different techniques for drawing blood are available 1-3.
Here, we present two techniques for drawing blood from rats, each with its specific applications.
Blood draw from the saphenous vein, provided it is done properly, induces minimal distress in animals and does not require anesthesia. This technique allows repeated draws of small amounts of blood, such as needed for pharmacokinetic studies 4,5, determining plasma chemistry, or blood counts 6.
Cardiac puncture allows the collection of large amounts of blood from a single animal (up to 10 ml of blood can be drawn from a 150 g rat). This technique is therefore very useful as a terminal procedure when drawing blood from the saphenous would not provide a large enough sample. We use cardiac puncture when we need sufficient amounts of serum from a specific strain of rats to grow T lymphocyte lines in vitro 4-9.

Blood draws are necessary in a large number of studies, for example to study the pharmacokinetics profile of a compound. Here, we demonstrate how to draw blood from rats using two techniques: blood draw from the saphenous vein or by cardiac puncture.

Drawing blood from rodents is necessary for a large number of both in vitro and in vivo studies. Sites of blood draws are numerous in rodents: ...

Optimized Interferon-gamma ELISpot Assay to Measure T Cell Responses in the Guinea Pig Model after Vaccination

The guinea pig has played a pivotal role as a relevant small animal model in the development of vaccines for infectious diseases such as tuberculosis, influenza, diphtheria, and viral hemorrhagic fevers. We have demonstrated that plasmid-DNA (pDNA) vaccine delivery into the skin elicits robust humoral responses in the guinea pig. However, the use of this animal to model immune responses was somewhat limited in the past due to the lack of available reagents and protocols to study T cell responses. T cells play a pivotal role in both immunoprophylactic and immunotherapeutic mechanisms. Understanding T cell responses is crucial for the development of infectious disease and oncology vaccines and accommodating delivery devices. Here we describe an interferon-gamma (IFN-&#947;) enzyme-linked immunospot (ELISpot) assay for guinea pig peripheral blood mononuclear cells (PBMCs). The assay enables researchers to characterize vaccine-specific T-cell responses in this important rodent model. The ability to assay cells isolated from the peripheral blood provides the opportunity to track immunogenicity in individual animals.

The development of the interferon-gamma ELISpot assay for guinea pig PBMCs allows the characterization of T-cell responses in this highly relevant model for studying infectious diseases. We have applied the assay to measure T cell responses associated with intradermal delivery of DNA vaccines.

The guinea pig has played a pivotal role as a relevant small animal model in the development of vaccines for infectious diseases such as tuberculosis, ...

Immunology and Infection

Subclavian Vein Puncture As an Alternative Method of Blood Sample Collection in Rats

Blood collection with enough blood volume is essential in animal experiments. Blood collection from the tail vein of rats is popular and less stressful compared to other more aggressive methods such as retro-orbital plexus sample collection. However, this blood collection method is sometimes limited by an unsatisfactory success rate. Here, we introduce a method for blood collection through the subclavian vein puncture. The subclavian vein is located just under the clavicle and this vein is large enough to fulfill the volume requirements of blood collection. Our results show that this method is safe and applicable for blood collection sampling with the required blood volume. Blood collection through the subclavian vein puncture could serve as an alternative blood collection method in case of failed tail vein blood sampling in rats.

Here, we present a protocol to collect blood samples from the rat subclavian vein.

Blood collection with enough blood volume is essential in animal experiments. Blood collection from the tail vein of rats is popular and less stressful ...

Medicine

A Revised Surgical Approach to Induce Endolymphatic Hydrops in the Guinea Pig

Endolymphatic hydrops is an enlargement of scala media that is most often associated with Meniere&#39;s disease, though the pathophysiologic mechanism(s) remain unclear. In order to adequately study the attributes of endolymphatic hydrops, such as the origins of low-frequency hearing loss, a reliable model is needed. The guinea pig is a&#160;good model because it hears in the low-frequency regions that are putatively affected by endolymphatic hydrops. Previous research has demonstrated that endolymphatic hydrops can be induced surgically via intradural or extradural approaches that involve drilling on the endolymphatic duct and sac. However, whether it was possible to create an endolymphatic hydrops model using an extradural approach that avoided dangerous drilling on the endolymphatic duct and sac was unknown. The objective of this study was to demonstrate a revised extradural approach to induce experimental endolymphatic hydrops at 30 days post-operatively by obliterating the endolymphatic sac and injuring the endolymphatic duct with a fine pick. The sample size consisted of seven guinea pigs. Functional measurements of hearing were made and temporal bones were subsequently harvested for histologic analysis. The approach had a success rate of 86% in achieving endolymphatic hydrops. The risk of cerebrospinal fluid leak was minimal. No perioperative deaths or injuries to the posterior semicircular canal occurred in the sample. The presented method demonstrates a safe and reliable way to induce endolymphatic hydrops at a relatively quick time point of 30 days. The clinical implications are that the presented method provides a reliable model to further explore the origins of low-frequency hearing loss that can be associated endolymphatic hydrops.

This article demonstrates an extradural approach to obliterate the guinea pig endolymphatic sac and injure the endolymphatic duct with a fine pick in order to induce experimental endolymphatic hydrops.

Endolymphatic hydrops is an enlargement of scala media that is most often associated with Meniere&#39;s disease, though the pathophysiologic mechanism(s) ...

Neuroscience

Continuous Blood Sampling in Small Animal Positron Emission Tomography/Computed Tomography Enables the Measurement of the Arterial Input Function

For quantitative analysis and bio-kinetic modeling of positron emission tomography/computed tomography (PET/CT) data, the determination of the temporal blood time-activity concentration also known as arterial input function (AIF) is a key point, especially for the characterization of animal disease models and the introduction of newly developed radiotracers. The knowledge of radiotracer availability in the blood helps to interpret PET/CT-derived data of tissue activity. For this purpose, online blood sampling during the PET/CT imaging is advisable to measure the AIF. In contrast to manual blood sampling and image-derived approaches, continuous online blood sampling has several advantages. Besides the minimized blood loss, there is an improved resolution and a superior accuracy for the blood activity measurement. However, the major drawback of online blood sampling is the costly and time-consuming preparation to catheterize the femoral vessels of the animal. Here, we describe an easy and complete workflow for catheterization and continuous blood sampling during small animal PET/CT imaging and compared it to manual blood sampling and an image-derived approach. Using this highly-standardized workflow, the determination of the fluorodeoxyglucose ([18F]FDG) AIF is demonstrated. Further, this procedure can be applied to any radiotracer in combination with different animal models to create fundamental knowledge of tracer kinetic and model characteristics. This allows a more precise evaluation of the behavior of pharmaceuticals, both for diagnostic and therapeutic approaches in the preclinical research of oncological, neurodegenerative and myocardial diseases.

Here a protocol for continuous blood sampling during PET/CT imaging of rats to measure the arterial input function (AIF) is described. The catheterization, the calibration and setup of the system and the data analysis of the blood radioactivity are demonstrated. The generated data provide input parameters for subsequent bio-kinetic modeling.

For quantitative analysis and bio-kinetic modeling of positron emission tomography/computed tomography (PET/CT) data, the determination of the temporal ...

Sampling Blood from the Lateral Tail Vein of the Rat

Blood samples are commonly obtained in many experimental contexts to measure targets of interest, including hormones, immune factors, growth factors, proteins, and glucose, yet the composition of the blood is dynamically regulated and easily perturbed. One factor that can change the blood composition is the stress response triggered by the sampling procedure, which can contribute to variability in the measures of interest. Here we describe a procedure for blood sampling from the lateral tail vein in the rat. This procedure offers significant advantages over other more commonly used techniques. It permits rapid sampling with minimal pain or invasiveness, without anesthesia or analgesia. Additionally, it can be used to obtain large volume samples (upwards of 1 ml in some rats), and it may be used repeatedly across experimental days. By minimizing the stress response and pain resulting from blood sampling, measures can more accurately reflect the true basal state of the animal, with minimal influence from the sampling procedure itself.

Blood samples are useful for assessing biomarkers of physiological states or disease in vivo. Here we describe the methodology to sample blood from the lateral tail vein in the rat. This method provides rapid samples with minimal pain and invasiveness.

Blood samples are commonly obtained in many experimental contexts to measure targets of interest, including hormones, immune factors, growth factors, ...

Repetitive Blood Sampling from the Subclavian Vein of Conscious Rat

Rats are widely used in pharmacokinetics (PK) and toxicokinetic (TK) studies that need to collect a certain amount of blood at specific time points to detect drug exposure. The rat blood sampling method determines the quality of the plasma and further affects the precision of the test results. The subclavian vein blood collection method described in this protocol collects blood samples repeatedly in the conscious state of animals to meet the needs of PK and TK tests. The skills of restraint handling and appropriate procedure of needle incision ensure the success rate of blood collection. It is easy to operate while ensuring the quality of plasma and at the same time catering to animal welfare. However, this method requires skilled operation, and an improper one may cause animal weakness, pain, lameness, and even mortality. The current method has been used in the testing facility for a 4-week oral toxicity study in Sprague Dawley (SD) rats with TK. The maximum amount of blood collected within 24 h did not exceed 20% of the animal's total blood. The animals' body weight was more than 200 g for males and females. The data showed that the animals' bodyweight increased steadily every week, and the clinical observation was normal after repetitive sample collection.

The present protocol describes a simple and efficient method for collecting blood from the subclavian vein in rats. It enables rapid, timely, and easily identifiable sampling without anesthesia and obtains high-quality blood through repetitive sample collection.

Rats are widely used in pharmacokinetics (PK) and toxicokinetic (TK) studies that need to collect a certain amount of blood at specific time points to ...

Transdermal Measurement of Glomerular Filtration Rate in Mechanically Ventilated Piglets

Transdermal measurement of glomerular filtration rate (GFR) has been used to evaluate kidney function in conscious animals. This technique is well established in rodents to study acute kidney injury and chronic kidney disease. However, GFR measurement using the transdermal system has not been validated in pigs, a species with a similar renal system to humans. Hence, we investigated the effect of sepsis on transdermal GFR in anesthetized and mechanically ventilated neonatal pigs. Polymicrobial sepsis was induced by cecal ligation and puncture (CLP). The transdermal GFR measurement system consisting of a miniaturized fluorescence sensor was attached to the pig's shaved skin to determine the clearance of fluorescein-isothiocyanate (FITC) conjugated sinistrin, an intravenously injected GFR tracer. Our results show that at 12 h post-CLP, serum creatinine increased with a decrease in GFR. This study demonstrates, for the first time, the utility of the transdermal GFR approach in determining renal function in mechanically ventilated, neonatal pigs.

Glomerular filtration rate (GFR) is the ideal marker for assessing kidney function. However, the standard measurement method using inulin injection with serial blood and urine analysis is impractical. This article delineates a practical method to measure GFR transdermally in piglets.

Transdermal measurement of glomerular filtration rate (GFR) has been used to evaluate kidney function in conscious animals. This technique is well ...

Comparative Study of Blood Collection Techniques in Rats

Modified Tail Vein and Penile Vein Puncture for Blood Sampling in the Rat Model

Blood samples are required in most experimental animal designs to assess various hematological parameters. This paper presents two procedures for blood collection in rats: the lateral tail vein puncture and the dorsal penile vein puncture, which offer significant advantages over other previously described techniques. This study shows that these two procedures allow for fast sampling (under 10 min) and yield sufficient blood volumes for most assays (202 &#956;L &#177; 67.7 &#956;L). The dorsal penile vein puncture must be done under anesthesia, whereas the lateral tail vein puncture can be done on a conscious, restrained animal.
Alternating these two techniques, therefore, enables blood draw in any situation. While it is always recommended for an operator to be assisted during a procedure to ensure animal welfare, these techniques require only a single operator, unlike most blood sampling methods that require two. Moreover, whereas these previously described methods (e.g., jugular stick, subclavian vein blood draw) require extensive prior training to avoid harm to or death of the animal, tail vein and dorsal penile vein puncture are rarely fatal. For all these reasons, and according to the context (e.g., for studies including male rats, during the perioperative or immediate postoperative period, for animals with thin tail veins), both techniques can be used alternately to enable repeated blood draws.

Author Spotlight: Context Dependent Blood Collection Methods in Rats 

Here, we present a protocol to offer rapid, easy, and reliable blood collection alternatives for the rat model. We describe three different blood sampling methods according to the context: tail vein puncture under anesthesia or on a conscious animal, and dorsal penile vein puncture under anesthesia.

Blood samples are required in most experimental animal designs to assess various hematological parameters. This paper presents two procedures for blood ...

Blood Withdrawal I

Source: Kay Stewart, RVT, RLATG, CMAR; Valerie A. Schroeder, RVT, RLATG. University of Notre Dame, IN
Blood collection is a common requirement for research studies that involve mice and rats. The method of blood withdrawal in mice and rats is dependent upon the volume of blood needed, the frequency of the sampling, the health status of the animal to be bled, and the skill level of the technician.1 All methods discussed-retro-orbital sinus bleeds, initial tail snip bleeds, and intracardiac bleeds-require the use of a general anesthesia.