About

Margaret Gruen is an Associate Professor of Behavioral Medicine at North Carolina State University College of Veterinary Medicine. She completed her veterinary degree at the University of Illinois and subsequently undertook an internship and residency in veterinary behavior at NCSU. She earned a Masters in Veterinary Public Health and became a board-certified veterinary behaviorist. After working on the faculty at NCSU, she pursued a PhD focused on understanding behaviors associated with pain in cats with naturally-occurring arthritis. She spent two years at Duke University, where she co-directed the Canine Cognition Center, before returning to NCSU. Her research areas include spontaneous animal disease models, animal behavior, chronic pain, welfare, cognition, and anxiety.

Research topics

• Medicine
• Psychology
• Neuroscience
• Cognitive psychology
• Internal medicine
• Audiology
• Computer Science
• Pathology
• Physical therapy
• Developmental psychology
• Embedded system
• Physical medicine and rehabilitation
• Simulation
• Engineering
• Evolutionary biology
• Psychiatry
• Biology

Selected publications

• Innovative modeling of the biopsychosocial model in animals: Validation of outcomes for assessing emotional and cognitive domains affected by naturally-occurring chronic pain in dogs

  Open MIND · 2026-02-19

  otherOpen access1st authorCorresponding
  OA PDFDOI

• Low-dose radiation therapy for idiopathic or interstitial cystitis in male cats

  Journal of Veterinary Internal Medicine · 2026-01-01

  articleOpen access

  BACKGROUND: Idiopathic cystitis (IC) accounts for the majority of lower urinary tract (LUT) disease in cats and is characterized by recurrent clinical signs or urethral obstruction (UO), presenting ongoing challenges in clinical management. HYPOTHESIS/OBJECTIVES: Determine the feasibility of using single-fraction low-dose radiotherapy (RT) to reduce rate of re-obstruction and recurrence of clinical signs in cats with feline idiopathic cystitis. ANIMALS: Fifteen client-owned male cats with recent history of severe IC and historical UO that remained symptomatic despite environmental modification and pharmacological management. METHODS: An IACUC-approved, single-arm, single-institution, prospective clinical trial was conducted to evaluate the clinical effects of irradiating the entire LUT with a single 6 Gy fraction. RESULTS: One cat was immediately lost to follow-up, and 1 died 516 days after RT. The remaining 13 cats were alive at the time of data analysis, with a median follow-up of 548 (range 70-1307) days. All but 1 had symptomatic improvement. Six had a single flare-up of signs of IC at a median of 243 days after RT (range 4-395 days). After RT, 1 cat had a recurrent UO, which occurred at 11 months and was managed surgically. CONCLUSIONS AND CLINICAL IMPORTANCE: In this cohort of severely affected cats, >90% had apparent improvement in clinical signs after RT, with no documented adverse effects, demonstrating that in addition to environmental modification, RT is a promising tool for managing IC in male cats.

  PublisherDOI

• Artemin/GFRA3 axis and TRP channels: molecular insights from a feline model of osteoarthritis

  Frontiers in Pain Research · 2026-03-17

  articleOpen access

  Introduction: Degenerative Joint Disease (DJD) is a form of highly prevalent osteoarthritis in humans and animals, including cats, which causes significant pain and hypersensitivity. Despite its prevalence, the mechanisms underlying the DJD-associated pain in cats are poorly understood. While transient receptor potential (TRP) ion channels are expressed in the dorsal root ganglia (DRG) and are implicated in osteoarthritis pain (e.g., through Artemin/GFRA3-mediated changes to TRPV1 and TRPA1 electrical properties), there is currently only indirect evidence of TRP ion channel expression in the feline DRG. This study aims to address this knowledge gap. Methods: calcium imaging was used to confirm the functional expression of TRPV1, TRPV2, TRPA1, and TRPM8 in healthy cat DRG neurons. A quantitative reverse transcription-polymerase chain reaction (qRT-PCR) with SYBR green was used to confirm and compare mRNA expression of pain sensors including TRPV1, TRPV2, TRPV4, TRPA1, TRPM3, TRPM8, MRGPRD, TAC1, and GFRA3 in the DRG neurons of healthy cats and DJD group. Finally, serum artemin concentrations were quantified using enzyme linked-immunosorbent assay (ELISA) and compared between healthy and DJD cats. Results: Functional responses of TRPV1, TRPV2, TRPA1 and TRPM8 were determined via calcium imaging in DRG neurons obtained from healthy cats. Gene expression is further extended into healthy vs. DJD cats. While TRPV1, TRPV2, and TRPM8 showed a >1.5-fold increase in cats with DJD compared to healthy controls, MRGPRD mRNA expression showed a corresponding ∼1.5-fold decrease. However, these increases or decreases in fold-change did not reach statistical significance. GFRA3, a receptor for artemin, was found to be expressed in the cat DRG, though its levels remained unchanged in DJD-affected cats. Lastly, a significant association was found between serum artemin concentrations and radiographic DJD scores but not with veterinarian pain scores. Discussion: Our findings characterize functional expression of several pain and hypersensitivity-associated TRP ion channels in cat DRG neurons and identify the Artemin/GFRA3/TRP axis as a potential driver of chronic pain. The expression of channels, including TRPV1, TRPA1, and TRPM8 modulated by Artemin/GFRA3 pathway was confirmed. Bridging these cellular findings to DJD state, the observed correlation between serum artemin concentrations and radiographic DJD scores further implicates this pathway in disease severity. These results provide potential early evidence that the Artemin/GFRA3/TRP axis drives pain in feline DJD. This conservation is consistent with findings in other species, such as rodents and canines, suggesting translational relevance for therapeutic targeting.

  PublisherOA PDFDOI

• A reliable and holistic approach to evaluating hearing and cognitive auditory processing in adult and aged companion dogs

  Scientific Reports · 2026-02-10

  articleOpen access

  Presbycusis affects both peripheral and central auditory systems in people and dogs. While comprehensive behavioral hearing tests exist for people, veterinary audiology lacks methods to assess central auditory function in dogs. This study aimed to develop behavioral hearing tests for dogs. We introduced two novel assessments: the Enclosed Canine Hearing Observation (ECHO) test and the Evaluation of Auditory Reward Response (EARR) test. Fourteen adult dogs with normal hearing, five deaf and five senior dogs were included. The ECHO test evaluates a dog's ability to detect sounds; only hearing dogs responded to sounds with behaviors such as orienting the head or body towards the sound source. The EARR test assesses integration of auditory perception with learning and memory by associating sound cues with rewards; hearing dogs successfully learned and completed the sound-reward task while deaf dogs did not. Senior dogs were able to perform both tasks. Our findings confirmed that these tests are feasible in companion dogs and can differentiate between those with normal hearing and those with hearing impairment. Furthermore, both tests showed high test-retest, intra- and inter-observer reliability. These tests can be paired with electrophysiological tests and MRI evaluations, advancing our ability to detect and characterize presbycusis in dogs.

  PublisherOA PDFDOI

• Physical Activity Monitors in Companion Animal Chronic Pain Research—A Review Focused on Osteoarthritis Pain

  Animals · 2025-07-10 · 1 citations

  reviewOpen access

  Accelerometry-based physical activity monitors (PAMs) are a useful tool to collect objective measurements of physical activity and movement. Recently, there has been an increased utilization of PAMs in companion animal chronic pain research. However, a general lack of understanding of PAMs contributes to challenges and misconceptions around the interpretation and utility of these data. Commercially available devices differ in how they acquire, process, report, and, in some cases, interpret data. Furthermore, various factors relating to the subject, such as age, body condition, and species, clearly influence PAM data, and on top of this, understanding the biological meaning of PAM data is in its relative infancy. This review examines the principles of PAM technology and the technical and biological considerations when applying PAMs to companion animal chronic pain research, in particular osteoarthritis pain research. It also provides an overview of applications of these devices in veterinary chronic pain research thus far, and the potential of these devices in future studies.

  PublisherDOI

• Salivary cortisol is an unreliable correlate of serum cortisol in adult pet dogs and assistance dog puppies

  Scientific Reports · 2025-05-08 · 3 citations

  articleOpen accessSenior author

  Cortisol is widely used in mammals as a measure of HPA axis response. To estimate response to an acute stressor, minimize pain and ease sample collection, salivary cortisol has become preferred over serum cortisol across a variety of species. This includes domestic dogs in which research with laboratory dogs initially demonstrated the predicted relationship between cortisol concentrations in serum and salivary levels sampled within minutes of each other. The Model Population Hypothesis suggests a laboratory dog should be physiologically representative of all dogs. We provide a critical test of this idea by providing the first validation of salivary cortisol against serum measures in healthy puppies less than six months of age (n = 34; 8 to 20-week-old Labrador x Golden Retrievers) as well as a group of healthy adult pet dogs (n = 38). Following previously established methodology, blood and saliva were collected within 4 min of each other. Puppies were sampled multiple times while adults were sampled once. We found that salivary and serum cortisol are poorly correlated in our puppies r(216) = - 0.092, p = 0.178, and adult dogs (r(36) = 0.092, p = 0.582). Our results suggest that previously validated methods with laboratory dogs may not translate to healthy puppies and pet dogs, particularly those less than six months of age. Further research is now needed to identify a salivary sampling method that might allow for this less invasive sampling technique to be used in puppies and pet dogs living in a range of real-world contexts.

  PublisherOA PDFDOI

• An Integrated Wearable Sensor System for Simultaneous Pull and Pace Characterization in Guide Dogs

  2025-11-28

  article

  Guide dogs provide vital support to individuals with visual impairments, yet the training process demands significant investment of time and resources. A significant component of this process is mutually identifying the right individual for each guide dog based on factors such as natural walking speed and handle-pull characteristics. We present a novel proof-of-concept wearable sensor system that records pull-force and harness motion data to aid in guide dog training and evaluation. The system integrates a modified harness with force sensors and an inertial measurement unit (IMU), providing a user-friendly and low-cost wireless solution for data collection during training sessions. Preliminary results show a strong correlation between average pull-force and profiling from professionals at a prominent guide dog school. Variations in left-to-right force distribution was found across individual dogs. Additionally, the system enables collection of motion data simultaneously with pull. We present early work validating pace and gait estimation using harness-based IMU data, with commercial gait analysis equipment as ground truth. We apply preliminary machine learning techniques to extract key features from pull and motion data with the goal of enabling advanced visualization and analysis of future gait and pull characteristics. As a quantitative objective tool, the presented system paves the way for improving guide dog training, optimizing dog-handler pairings, and potentially improving the success rate of dog training programs in general.

  PublisherDOI

• Feline chronic pain management: the importance of a team approach for optimal outcomes

  Journal of Feline Medicine and Surgery · 2025-11-01 · 1 citations

  articleOpen accessSenior author

  This article reviews the importance of a team approach in feline chronic pain management for optimal outcomes. It discusses the role of different stakeholders and the importance of collaboration, communication and strategies for improved experiences for cats and caregivers on their journey. Chronic pain is maladaptive and negatively impacts on all domains of animal welfare. It can occur by itself, but most commonly is secondary to other chronic conditions. Ensuring that cats suffering from chronic pain are managed effectively requires a collaborative approach between all stakeholders, including client care staff, veterinarians, veterinary nurses or technicians, veterinary support staff and clinic management, as well as the cat and the caregiver. The journey starts with clinical signs displayed by the cat and perceived by the caregiver, and ends, for most cases, with end-of-life considerations. Diagnosis of chronic pain and design of a treatment plan result from a partnership between the caregiver and veterinary team. Management of chronic pain is focused on maintaining quality of life while empowering caregivers to be part of the healthcare team, avoiding adverse effects from medication and balancing comorbidities. The journey for cats and their caregivers is influenced by numerous factors, including the clinical condition of the cat and the caregiver's response to different burdens, but mostly by the care they receive from the clinic and veterinary teams involved in the process. Empathetic communication is paramount and helps to optimise the cat's care while supporting caregivers.

  PublisherDOI

• Factors influencing, and associated with, physical activity patterns in dogs with osteoarthritis-associated pain

  Frontiers in Veterinary Science · 2025-03-19 · 5 citations

  articleOpen accessCorresponding

  Background: Accelerometry can be used to measure physical activity and is a validated objective measure for evaluating the impact of osteoarthritis (OA) pain in companion animals. However, several factors other than OA pain can affect physical activity in dogs, and relatively little is understood about their influence. Functional linear modeling (FLM) is an approach for analyzing and visualizing high-frequency longitudinal data such as physical activity and can be used to assess the influence of factors on activity patterns. This study aimed to use FLM to investigate the effect of various factors on physical activity patterns in a cohort of dogs with OA pain. Methods: Ninety-nine client-owned dogs with radiographic and clinical evidence of OA were fitted with a collar-based activity monitor (Actigraph GT3X). Average vector magnitudes were recorded once per minute over 7 days and averaged to create 24-h, per-minute activity profiles for each dog. Demographic information, owner completed OA Clinical Metrology Instruments (Liverpool Osteoarthritis in Dogs and Canine Brief Pain Inventory), and veterinary examination findings (joint pain, muscle atrophy) were collected. Data were analyzed using FLM and a custom R package to evaluate the effect of each factor on 24-h patterns of physical activity. Results: At times of peak activity within a 24-h period, dogs with hindlimb OA pain, higher age, higher Clinical Metrology Instrument scores, higher joint pain, greater Body Condition Score and greater muscle atrophy all had decreased activity profiles. However, only age, hindlimb joint pain, and hindlimb muscle atrophy had statistically significant effects on physical activity. Conclusions and clinical relevance: Several factors influence activity patterns in dogs with OA pain. Understanding what and how factors influence patterns in dogs with OA pain will help refine the usage of physical activity as an objective outcome measure in clinical pain studies.

  PublisherOA PDFDOI

• Aging is modifiable: current perspectives on healthy aging in companion dogs and cats

  Journal of the American Veterinary Medical Association · 2025-10-01 · 2 citations

  articleOpen access

  Aging is a universal, continuous, and complex process in which an animal's biological ability to resist, react to, and recover from environmental stressors declines and there is an alteration of physiological processes in response to accumulating cellular damage. In companion dogs and cats, aging is often perceived as an unmodifiable decline in physical and mental capabilities combined with increased morbidity, all aligned with chronological age. An insufficient understanding of healthy aging means missed opportunities to alter the trajectory of health span and maintain overall quality of life despite those changes that are inevitable. We believe that the course of aging is modifiable throughout an individual's entire life, with healthy, or successful, aging being an achievable goal. We explored herein 3 aspects of healthy aging: the need for a better scientific understanding of aging processes in dogs and cats and practical potential of biological aging clocks; a meaningful definition of healthy aging; and greater use of validated clinical monitoring tools and resources. A universal, meaningful, and actionable definition of healthy aging is needed to dissociate aging from declining health and poor quality of life in all their manifestations. The unique relationship between pets and their caregivers may demand a more expansive definition than that for humans. We propose that healthy aging in dogs and cats should be regarded as aging in which the individual maintains functional capabilities and develops resilience sufficient to meet their own physical, behavioral, social, and emotional needs throughout all adult life stages, while sustaining the human-animal bond.

  PublisherOA PDFDOI

Recent grants

• Longitudinal Cognitive and Emotional Development in Working Dogs

  NIH · $1.9M · 2019–2026

Frequent coauthors

• B. Duncan X. Lascelles

  North Carolina State University

  93 shared

• Emily H. Griffith

  39 shared

• Beth Case

  MedStar Washington Hospital Center

  34 shared

• Barbara L. Sherman

  North Carolina State University

  24 shared

• Andrea Thomson

  North Carolina State University

  22 shared

• Natasha J. Olby

  North Central State College

  22 shared

• Dávid Kňazovický

  North Carolina State University

  21 shared

• William Maixner

  DaVita Clinical Research (United States)

  20 shared

Labs

• Behavioral MedicinePI

Awards & honors

• Board-Certified Veterinary Behaviorist