Monika Huss, DVM, MS, received her D.V.M. from Western University of Health Sciences in 2010 and completed her residency training in Laboratory Animal Medicine at Stanford in 2015. Upon completion, she joined the Veterinary Service Center as a clinical veterinarian before becoming a clinical instructor for the Department of Comparative Medicine in 2016. Her interests include animal welfare, pain recognition, anesthesia and analgesia.

Academic Appointments

Professional Education

  • DVM, Western University of Health Sciences (2010)
  • MS, Stanford University, Biological Sciences (2006)
  • BA, Stanford University, Human Biology (2005)

2023-24 Courses

All Publications

  • Efficacy of Supplemental Diet Gels for Preventing Postoperative Weight Loss in Mice (Mus musculus). Journal of the American Association for Laboratory Animal Science : JAALAS Gates, K. V., Alamaw, E., Jampachaisri, K., Huss, M. K., Pacharinsak, C. 2022


    This study investigated whether the use of commercially available diet gels prevented the postoperative weight loss associated with major survival surgery in mice. C57BL/6 mice were divided into 3 groups (n = 9 per group) that received moistened chow pellets alone or with one of 2 commercially available diet gels. Mice began receiving the test diets 3 d before surgery (baseline) and were weighed daily for 7 d after surgery. On day 0, mice underwent ventral midline laparotomy, during which the intestines were manipulated for 2 min and a segment of jejunum was briefly clamped. Compared with the baseline value for the same group, body weights for the mice that received moistened chow only were significantly lower on all postoperative days (days 1 through 7). In contrast, body weights of mice that received both moistened chow and diet gel differed from baseline only on days 2 and 3 for one product and were never different from baseline for the other product. This study indicates that the combination of diet gel and moistened chow prevented or mitigated postoperative weight loss after a laparotomy procedure in mice.

    View details for DOI 10.30802/AALAS-JAALAS22-000030

    View details for PubMedID 36410729

  • A Review of Long-acting Parenteral Analgesics for Mice and Rats. Journal of the American Association for Laboratory Animal Science : JAALAS Huss, M. K., Pacharinsak, C. 2022


    Appropriate analgesia is a crucial part of rodent postoperative and postprocedural pain. Providing appropriate analgesia is an ethical obligation, a regulatory requirement, and an essential element of obtaining quality scientific results and conducting reproducible data. Meeting these requirements is facilitated by practical, efficient and safe delivery methods for providing analgesia. Over the last decade, long-acting analgesics have gained widespread use in research animal medicine to avoid or treat postoperative or postprocedural pain while minimizing handling-related time and stress. Long-acting formulations of analgesics suitable for rodents are available for opioids, NSAIDs, and local anesthetics. The goal of this review is to summarize the currently available long-acting formulations of analgesics for rodents and to provide recommendations to veterinarians and researchers regarding their use.

    View details for DOI 10.30802/AALAS-JAALAS-22-000061

    View details for PubMedID 36379476

  • Efficacy of 3 Buprenorphine Formulations for the Attenuation of Hypersensitivity after Plantar Incision in Immunodeficient NSG Mice. Journal of the American Association for Laboratory Animal Science : JAALAS Arthur, J. D., Alamaw, E. D., Jampachairsri, K., Sharp, P., Nagamine, C. M., Huss, M. K., Pacharinsak, C. 2022


    Buprenorphine is perhaps the most prescribed analgesic for management of postoperative pain in mice. Although various buprenorphine formulations are effective in commonly used immunocompetent mouse strains, a knowledge gap exists regarding its efficacy in immunodeficient mice. Here we used a plantar incision to evaluate the efficacy of 3 buprenorphine formulations for attenuating postoperative mechanical and thermal hypersensitivity in the immunodeficient NSG mouse strain. We also characterized the pharmacokinetics of these formulations over a 72-h period. We hypothesized that all 3 buprenorphine formulations evaluated-the standard preparation and 2 extended-release products (Bup-HCl, Bup-ER, and Bup-XR, respectively)-would attenuate postoperative mechanical and thermal hypersensitivity resulting from a plantar incision in NSG mice. Male and female NSG mice (n = 48) were allocated to 4 treatment groups: saline (0.9% NaCl, 5 mL/kg SC once); Bup-HCl (0.1 mg/kg SC, BID for 2 d); Bup-ER (1.0 mg/kg SC once); and Bup-XR (3.25 mg/kg SC once). Mechanical and thermal hypersensitivity assessments were conducted 24 h before surgery and at 4, 8, 24, 48, and 72 h afterward. All groups of mice showed mechanical and thermal hypersensitivity within the first 24 h after surgery. Behavioral pain indicators (guarding, toe-touching [intermittent partial weight bearing], licking the incision, vocalizations) were observed in some mice from each group at every postoperative time point. Plasma buprenorphine was measured in a separate group of mice and concentrations surpassed the suggested therapeutic level (1.0 ng/mL) for less than 4 h for Bup-HCl, for at least 24 h for Bup-ER, and for 72 h for Bup-XR. Our results indicate that at the dosages studied, these buprenorphine formulations do not adequately attenuate postoperative mechanical and thermal hypersensitivity in the plantar incisional model in NSG mice. These findings support the need for strain-specific analgesic protocols for mice used in research.

    View details for DOI 10.30802/AALAS-JAALAS-22-000058

    View details for PubMedID 36068076

  • Extended-release Buprenorphine, an FDAindexed Analgesic, Attenuates Mechanical Hypersensitivity in Rats (Rattus norvegicus). Journal of the American Association for Laboratory Animal Science : JAALAS Alamaw, E. D., Franco, B. D., Jampachaisri, K., Huss, M. K., Pacharinsak, C. 1800; 61 (1): 81-88


    A new extended-release buprenorphine (XR), an FDA-indexed analgesic, has recently become available to the laboratory animal community. However, the effectiveness and dosing of XR has not been extensively evaluated for rats. We investigated XR's effectiveness in attenuating postoperative hypersensitivity in a rat incisional pain model. We hypothesized that high dose of XR would attenuate mechanical and thermal hypersensitivity more effectively than the low dose of XR in this model. We performed 2 experiments. In experiment 1, male adult Sprague-Dawley rats (n = 31) were randomly assigned to 1 of the 4 treatment groups: 1) saline (saline, 0.9% NaCl, 5 mL/kg, SC, once); 2) sustained-release buprenorphine (Bup-SR; 1.2 mg/kg, SC, once), 3) low-dose extended-release buprenorphine (XR-Lo; 0.65 mg/kg, SC, once), and 4) high-dose extended-release buprenorphine (XR-Hi; 1.3 mg/kg, SC, once). After drug administration, a 1 cm skin incision was made on the plantar hind paw under anesthesia. Mechanical and thermal hypersensitivity were evaluated 1 d before surgery (D-1), 4 h after surgery (D0), and for 3 d after surgery (D1, D2, and D3). In experiment 2, plasma buprenorphine concentration (n = 39) was measured at D0, D1, D2, and D3. Clinical observations were recorded daily, and a gross necropsy was performed on D3. Mechanical and thermal hypersensitivity were measured for 3 d (D0-D3) in the saline group. Bup-SR, XR-Lo, and XR-Hi effectively attenuated mechanical hypersensitivity for D0-D3. Plasma buprenorphine concentrations remained above 1 ng/mL on D0 and D1 in all treatment groups. No abnormal clinical signs were noted, but injection site reactions were evident in the Bup-SR (71%), XR-Lo (75%), and XR-Hi (87%) groups. This study indicates that XR-Hi did not attenuate hypersensitivity more effectively than did XR-Lo in this model. XR 0.65 mg/kg is recommended to attenuate postoperative mechanical hypersensitivity for up to 72 h in rats in an incisional pain model.

    View details for DOI 10.30802/AALAS-JAALAS-21-000081

    View details for PubMedID 34903316

  • Effectiveness of two extended-release buprenorphine formulations during postoperative period in neonatal rats. PloS one Zhang, M., Alamaw, E., Jampachaisri, K., Huss, M., Pacharinsak, C. 2022; 17 (10): e0276327


    Information on the effectiveness of a new long-lasting buprenorphine formulation, extended-release buprenorphine, in the neonatal rat is very limited. This study compares whether a high dose of extended-release buprenorphine (XR-Hi) attenuates thermal hypersensitivity for a longer period than a low dose of extended-release buprenorphine (XR-Lo) in a neonatal rat incisional pain model. Two experiments were performed. Experiment one: Male and female postnatal day-5 rat pups (n = 38) were randomly assigned to 1 of 4 treatment groups and received a subcutaneous administration of one of the following: 1) 0.9%NaCl (Saline), 0.1 mL; 2) sustained release buprenorphine (Bup-SR), 1 mg/kg; 3) XR-Lo, 0.65 mg/kg; and 4) XR-Hi, 1.3 mg/kg. Pups were anesthetized with sevoflurane in 100% O2 and a 5 mm long skin incision was made over the left lateral thigh and underlying muscle dissected. The skin was closed with surgical tissue glue. Thermal hypersensitivity testing (using a laser diode) and clinical observations were conducted 1 hour (h) prior to surgery and subsequently after 1, 4, 8, 24, 48, 72 h of treatment. Experiment two: The plasma buprenorphine concentration level was evaluated at 1, 4, 8, 24, 48, 72 h on five-day-old rat pups. Plasma buprenorphine concentration for all treatment groups remained above the clinically effective concentration of 1 ng/mL for at least 4 h in the Bup-SR group, 8 h in XR-Lo and 24 h in XR-Hi group with no abnormal clinical observations. This study demonstrates that XR-Hi did not attenuate postoperative thermal hypersensitivity for a longer period than XR-Lo in 5-day-old rats; XR-Hi attenuated postoperative thermal hypersensitivity for up to 4 h while Bup-SR and XR-Lo for at least 8 h in this model.

    View details for DOI 10.1371/journal.pone.0276327

    View details for PubMedID 36251720

  • Mouse Anesthesia: The Art and Science. ILAR journal Navarro, K. L., Huss, M., Smith, J. C., Sharp, P., Marx, J. O., Pacharinsak, C. 2021


    There is an art and science to performing mouse anesthesia, which is a significant component to animal research. Frequently, anesthesia is one vital step of many over the course of a research project spanning weeks, months, or beyond. It is critical to perform anesthesia according to the approved research protocol using appropriately handled and administered pharmaceutical-grade compounds whenever possible. Sufficient documentation of the anesthetic event and procedure should also be performed to meet the legal, ethical, and research reproducibility obligations. However, this regulatory and documentation process may lead to the use of a few possibly oversimplified anesthetic protocols used for mouse procedures and anesthesia. Although a frequently used anesthetic protocol may work perfectly for each mouse anesthetized, sometimes unexpected complications will arise, and quick adjustments to the anesthetic depth and support provided will be required. As an old saying goes, anesthesia is 99% boredom and 1% sheer terror. The purpose of this review article is to discuss the science of mouse anesthesia together with the art of applying these anesthetic techniques to provide readers with the knowledge needed for successful anesthetic procedures. The authors include experiences in mouse inhalant and injectable anesthesia, peri-anesthetic monitoring, specific procedures, and treating common complications. This article utilizes key points for easy access of important messages and authors' recommendation based on the authors' clinical experiences.

    View details for DOI 10.1093/ilar/ilab016

    View details for PubMedID 34180990

  • Lipid bound extended release buprenorphine (high and low doses) and sustained release buprenorphine effectively attenuate post-operative hypersensitivity in an incisional pain model in mice (Mus musculus). Animal models and experimental medicine Navarro, K., Jampachaisri, K., Huss, M., Pacharinsak, C. 2021; 4 (2): 129-137


    Background: Extended-release buprenorphine (XR) is indicated for pain management in rodents, but little is known about its use in mice. This study aimed to investigate whether high dose XR effectively attenuates post-operative hypersensitivity better than low dose XR in a mouse model of incisional pain.Methods: Mice (n=44) were randomly assigned to 1 of 4 treatment groups: (a) saline (1ml/kg SC, once); (b) sustained release buprenorphine (Bup-SR, 1mg/kg SC, once); (c) low dose extended-release buprenorphine (XR-lo, 3.25mg/kg SC, once); (d) high dose extended-release buprenorphine (XR-hi, 6.5mg/kg SC, once). On days -1, 0 (4hours), 1, 2, and 3, mechanical and thermal hypersensitivities were evaluated, and plasma buprenorphine concentrations were measured.Results: Mechanical (days 0-2) and thermal (days 0-1) hypersensitivities were observed in the saline group. Bup-SR, XR-lo, and XR-hi attenuated mechanical hypersensitivity on days 0, 1, and 2. None of the treatment groups, except XR-Lo on day 0, attenuated thermal hypersensitivity on days 0 or 1. Plasma buprenorphine concentration peaked at 4hours (day 0) in all treatment groups and remained greater than 1ng/mL on days 0-2. No abnormal clinical observations or gross pathologic findings were seen in any groups.Conclusion: The results indicate XR-hi did not effectively attenuate post-operative hypersensitivity better than XR-lo. Thus both 3.25 and 6.5mg/kg XR are recommended for attenuating post-operative hypersensitivity for at least up to 48hours in mice.

    View details for DOI 10.1002/ame2.12157

    View details for PubMedID 34179720

  • Sustained release buprenorphine effectively attenuates postoperative hypersensitivity in an incisional pain model in neonatal rats (Rattus norvegicus). PloS one Blaney, A. n., Jampachaisri, K. n., Huss, M. K., Pacharinsak, C. n. 2021; 16 (2): e0246213


    Despite the need for safe and effective postoperative analgesia in neonates, research regarding pain management in neonatal rodents is relatively limited. Here, we investigate whether sustained release buprenorphine (Bup SR) effectively attenuates thermal hypersensitivity in a neonatal rat model of incisional pain. Male and female postnatal day 3 Sprague Dawley rat pups (n = 34) were randomly assigned to one of four treatment groups: 1) saline (control), 0.1 mL, once subcutaneously (SC); 2) buprenorphine HCl (Bup HCl), 0.05 mg/kg, once SC; 3) low dose Bup SR (low-SR), 0.5 mg/kg, once SC; 4) high dose Bup SR (high-SR), 1 mg/kg, once SC. Pups were anesthetized with sevoflurane and a 0.5-cm long skin incision was made over the left lateral thigh. The underlying muscle was dissected and closed using surgical glue. Thermal hypersensitivity testing was performed at 24 h prior to surgery and subsequently at 1, 4, 8, 24, and 48 h post-surgery using an infrared diode laser. Thermal hypersensitivity was attenuated at 1 h post-surgery in the Bup HCl group, while it was attenuated through the entire postoperative period in both low-SR and high-SR groups. This data suggests that a single dose of low-SR (0.5 mg/kg) or high-SR (1 mg/kg) effectively attenuates thermal hypersensitivity for at least 8 h in neonatal rat pups.

    View details for DOI 10.1371/journal.pone.0246213

    View details for PubMedID 33534864

  • Buprenorphine, but not lidocaine, effectively attenuates post-operative thermal hypersensitivity in an incisional model in neonatal rats (Rattus norvegicus) SCANDINAVIAN JOURNAL OF LABORATORY ANIMAL SCIENCE Katz, E. M., Huss, M. K., Jampachaisri, K., Pacharinsak, C. 2021; 47 (1): 1–11
  • Continuous Rate Infusion of Alfaxalone during Ketamine-Xylazine Anesthesia in Rats. Journal of the American Association for Laboratory Animal Science : JAALAS Heng, K. n., Marx, J. O., Jampachairsi, K. n., Huss, M. K., Pacharinsak, C. n. 2020; 59 (2): 170–75


    Alfaxalone is an injectable anesthetic agent that is used in veterinary medicine for general anesthesia. We evaluated the safety and efficacy of alfaxalone delivered through continuous rate infusion by comparing ketamine-xylazine-alfaxalone (KXA) anesthesia with ketamine-xylazine (KX) anesthesia in Sprague-Dawley rats. Anesthesia was induced in male and female rats by using subcutaneous KX. After induction, rats in the KXA group received alfaxalone (10 mg/kg/h IV) for 35 min, whereas rats in the KX group did not receive alfaxalone. At the end of the trial, alfaxalone was discontinued, and xylazine was reversed in all rats by using atipamezole. Throughout anesthesia, we assessed forepaw withdrawal reflex (FPWR), hindpaw withdrawal reflex (HPWR), response to surgical stimulation, heart rate, respiratory rate, SpO₂, body temperature, and time to standing. KXA produced a reliable surgical plane of anesthesia, as evidenced by the loss of both FPWR and HPWR and lack of response to surgical stimulation in all 16 rats, whereas only 6 of the 16 rats in the KX group lost HPWR. No rat in the KXA group regained a paw withdrawal reflex during alfaxalone administration, whereas 3 of the 12 rats (25%) in the KX group that reached a surgical plane of anesthesia exited that plane within the 35-min timeframe. Neither heart rate, respiratory rate, SpO₂, body temperature, nor time to standing differed between KXA and KX groups; and there were no sex-associated differences in anesthesia response. These results indicate that alfaxalone (10 mg/kg/h IV) delivered through continuous rate infusion, in combination with ketamine and xylazine, provides a safe, prolonged, and reliable surgical plane of anesthesia in rats.

    View details for DOI 10.30802/AALAS-JAALAS-19-000122

    View details for PubMedID 32059754

  • Influence of Pain and Analgesia on Orthopedic and Wound-healing Models in Rats and Mice. Comparative medicine Huss, M. K., Felt, S. A., Pacharinsak, C. n. 2019


    The surgical stress response and resulting physiologic changes can lead to postoperative complications and negatively impact animal welfare. Although appropriate pain management is crucial to reduce the pain and stress response to surgery,analgesic choice can significantly affect bone and wound healing. This review aims to summarize data from rat and mouse studies and to provide recommendations for integrating analgesia into orthopedic and wound healing models in these species. Data from other species, such as humans, rabbits and other rodents, is included, where available. From these data, we conclude that for orthopedic surgical models, opioids, local anesthetics and dissociative agents have minimal impact onfracture healing; cyclooxygenase 2 (COX2) selective nonsteroidal antiinflammatory drugs (NSAID) may be used in the shortterm;and steroids should be avoided. For wound healing models, short-term systemic or topical opioids have negligible impact on wound healing; NSAID or local anesthetics may be used short-term; and systemic steroids should be avoided. Alternative analgesics such as tramadol, gabapentin, ketamine, and acetaminophen warrant consideration and further evaluation for both orthopedic and wound healing models. In all cases, researchers and veterinarians should work together todetermine the appropriate analgesic plan to minimize pain, as well as to minimize unwanted effects on the orthopedic and wound healing models themselves.

    View details for DOI 10.30802/AALAS-CM-19-000013

    View details for PubMedID 31561753

  • Evaluation of 3 Alcohol-based Agents for Presurgical Skin Preparation in Mice. Journal of the American Association for Laboratory Animal Science : JAALAS Huss, M. K., Casey, K. M., Hu, J. n., Moorhead, R. C., Chum, H. H. 2019


    Appropriate aseptic technique is a crucial component of rodent survival surgery. Ease of technique, surgical space constraint,batch surgery, and cost are factors that may affect researcher compliance with appropriate aseptic technique. The first part of this study compared 3 antiseptic preparation agents with the standard triplicate application of povidone-iodine and alcohol. Euthanized mice (n = 40) were shaved on the dorsum, and culture swabs were taken for RODAC plating and bacterial identification. Shaved sites were prepared by using one of the 4 antiseptic preparation agents. Culture samples were obtained immediately and at 20 min after antiseptic preparation. In the 2nd part of the study, 8 mice (n = 2 per group)were prepared for a survival surgical procedure by using one of the 4 antiseptic preparation agents to evaluate whether the antiseptic preparation agents caused skin irritation or impaired healing. Results from this study indicated that all 3 of the antiseptic agents evaluated were equally effective at reducing bacterial populations immediately and at 20 min after preparation. Histopathologic examination of the incision sites revealed signs of normal healing without lesions adjacent to the incision site. We conclude that all 3 of the products evaluated are comparable to traditional povidone-iodine and alcohol as agents for aseptic preparation of surgical sites.

    View details for DOI 10.30802/AALAS-JAALAS-19-000053

    View details for PubMedID 31753064

  • The Physiologic Effects of Isoflurane, Sevoflurane, and Hypothermia Used for Anesthesia in Neonatal Rats (Rattus norvegicus). Journal of the American Association for Laboratory Animal Science Huss, M. K., Chum, H. H., Chang, A. G., Jampachairsi, K., Pacharinsak, C. 2016; 55 (1): 83-88


    Information regarding effective anesthetic regimens for neonatal rat pups is limited. Here we investigated whether isoflurane or sevoflurane anesthesia maintains physiologic parameters more consistently than does hypothermia anesthesia in neonatal rat pups. Rat pups (age, 4 d) were randomly assigned to receive isoflurane, sevoflurane, or hypothermia. Physiologic parameters monitored at 1, 5, 10, and 15 min included heart rate (HR), respiratory rate (RR), and oxygen saturation (%SpO2). Other parameters evaluated were loss and return of righting reflex, paw withdrawal reflex, and maternal acceptance. Corticosterone and glucose were sampled at 20 min and 24 h after anesthesia induction. Once a surgical plane of anesthesia was achieved, a skin incision was made on the right lateral thigh. After the procedure, all pups were accepted and cared for by their dam. Isoflurane- and sevoflurane-treated pups maintained higher HR, RR, %SpO2, and glucose levels than did hypothermia-treated pups. For both the isoflurane and sevoflurane groups, HR and RR were significantly lower at 10 and 15 min after anesthesia than at 1 min. Compared with hypothermia, isoflurane and sevoflurane anesthesia provided shorter times to loss of and return of the righting reflex. Although corticosterone did not differ among the groups, glucose levels were higher at 20 min after anesthesia induction than at 24 h in all anesthetic groups. We conclude that both isoflurane and sevoflurane anesthesia maintain physiologic parameters (HR, RR, %SpO2) more consistently than does hypothermia anesthesia in 4-d-old rat pups.

    View details for PubMedID 26817984

  • Echocardiographic and Electrocardiographic Characteristics of Male and Female Squirrel Monkeys (Saimiri spp.). Journal of the American Association for Laboratory Animal Science Huss, M. K., Ikeno, F., Buckmaster, C. L., Albertelli, M. A. 2015; 54 (1): 25-28


    Cardiomyopathy is a leading cause of mortality in aging squirrel monkeys (Saimiri spp.). However, data regarding echocardiographic measures obtained from clinically healthy nonsedated squirrel monkeys have not been published, and few electrocardiographic data are available. Here we obtained echocardiographs without sedation and electrocardiographs with minimal sedation from 63 clinically healthy squirrel monkeys that ranged from 3 to 20 y in age. 2D and M-mode echocardiography were performed on nonsedated monkeys to determine the left ventricular internal diameters at systole and diastole and the ejection fraction. Electrocardiography was performed under sedation with ketamine (15 mg/kg). Parameters evaluated included heart rate; P-wave duration; lengths of the PR, QRS, and QT intervals; R-wave amplitude, and P-wave amplitude. Initial physical examination, electrocardiography, and echocardiography indicated normal cardiac function for all monkeys. The objectives of this study were to provide reference values for nonsedated echocardiography and ketamine-sedated electrocardiography of clinically normal squirrel monkeys and to determine correlates of age and sex in these values.

    View details for PubMedID 25651087

  • Supplemental Diet Aids Early Weaning of Crl:CD1(ICR) Mouse Pups. Huss, M., Chang, A., Nagamine, C. LAS Pro. . 2015
  • Prevalence of Batrachochytrium dendrobatidis in 120 Archived Specimens of Lithobates catesbeianus (American Bullfrog) Collected in California, 1924-2007. EcoHealth Huss, M., Huntley, L., Vredenburg, V., Johns, J., Green, S. 2013; 10 (4): 339-343


    The chytrid fungus, Batrachochytrium dendrobatidis (Bd), has been identified as a major cause of the recent worldwide amphibian decline. Numerous species in North America alone are under threat or have succumbed to Bd-driven population extinctions. The American bullfrog (Lithobates catesbeianus) has been reported as a tolerant carrier of Bd. In this report, we used a qPCR assay to test 120 archived American bullfrog specimens collected between 1924 and 2007 in California, USA and Baja California, Mexico. The overall prevalence of Bd infection in this archived population of L. catesbeianus was 19.2%. The earliest positive specimen was collected in Sacramento County, California, USA in 1928 and is to date the earliest positive archived Bd specimen reported globally. These data demonstrate that Bd-infected wild amphibians have been present in California longer than previously known.

    View details for DOI 10.1007/s10393-013-0895-6

    View details for PubMedID 24419668