About

Karen Munana is associated with the College of Veterinary Medicine at NC State University, where she is involved in fostering student engagement and supporting the academic and personal growth of veterinary students. Her role includes overseeing student programs and initiatives that enhance the educational experience, as evidenced by her position as CVM Director of Student Engagement. The college emphasizes a caring, collaborative culture, with a focus on student achievement, well-being, and extracurricular development, including research projects and international study opportunities. While specific details about her research focus or scholarly contributions are not provided in the page text, her leadership role underscores her commitment to student success and the advancement of veterinary education.

Research topics

• Medicine
• Internal medicine
• Anesthesia
• Surgery
• Physical medicine and rehabilitation
• Bioinformatics
• Mechanical engineering
• Genetics
• Physiology
• Microbiology
• Cardiology
• Biology

Selected publications

• Gut Microbiome Alterations in Canine Idiopathic Epilepsy: A Pairwise Case-Control Study

  bioRxiv (Cold Spring Harbor Laboratory) · 2026-04-03

  articleOpen access

  Abstract Background Idiopathic epilepsy (IE) is the most common chronic nervous system disorder of dogs, and its cause is poorly understood. Emerging evidence suggests that microbiome alterations can occur with IE via the microbiota-gut-brain axis. Therefore, we analyzed the fecal microbiomes of 98 dogs (49 IE, 49 control) in a pairwise case-control observational study using 16S rRNA gene sequencing. Results Although the microbial community was mostly similar between groups, IE was associated with a modest but significant shift in Weighted-Unifrac distance (P = 0.042). We used six differential abundance (DA) methods to identify differentially abundant amplicon sequencing variants (ASVs) between IE and control groups. Notably, one Collinsella ASV was found to be significantly more abundant in IE dogs by all six methods. The gut microbial compositions varied drastically across households (accounting for about 69% of the total variation), but did not have significant differences between sex, age, or breed. Phenobarbital administration in IE dogs had a significant effect on seizure control, and was not associated with changes in the microbiome. Conclusion Our findings suggest a relationship between gut microbiomes and IE. However, the specific mechanism needs to be further investigated.

  PublisherOA PDFDOI

• Adverse Drug–Drug Interaction Between Phenobarbital and Fluconazole in Two Dogs

  Journal of Veterinary Internal Medicine · 2025-07-01

  articleOpen accessSenior authorCorresponding

  Phenobarbital (PB) is an antiseizure medication widely used in dogs that is metabolized by hepatic cytochrome P450 (CYP) enzymes. Fluconazole, a commonly prescribed antifungal medication, inhibits several CYP isoenzymes and can impair PB metabolism. Genetic polymorphisms such as the CYP2C41 gene deletion can alter CYP activity and influence drug interactions, although not well characterized in dogs. We describe two epileptic dogs on chronic PB treatment that developed marked sedation and ataxia, and increased serum PB concentrations after receiving fluconazole. Both dogs were homozygous for the CYP2C41 deletion. Discontinuation of fluconazole resulted in decreased PB concentrations and resolution of clinical signs. These findings suggest fluconazole can inhibit PB metabolism, leading to clinically relevant toxicity, and this interaction does not require CYP2C41 enzyme expression. Monitoring PB concentrations during fluconazole co-administration is advised. Further characterization of the role of CYP enzymes in PB metabolism in dogs is needed to better predict drug interactions.

  PublisherOA PDFDOI

• Dissolution Characteristics of Split and Crushed Levetiracetam Extended‐Release Tablets in Comparison With Immediate‐Release Formulation

  Journal of Veterinary Pharmacology and Therapeutics · 2025-05-12 · 1 citations

  articleOpen accessSenior authorCorresponding

  Levetiracetam (LEV) is a commonly used antiseizure medication in dogs, available in immediate-release (LEV-IR) and extended-release (LEV-XR) formulations. LEV-XR improves owner compliance with less frequent dosing, but its lowest concentration tablet (500 mg) often exceeds recommended doses for small dogs. This study evaluated how modifying LEV-XR tablets affects dissolution rates, comparing intact, split, and crushed LEV-XR tablets with intact LEV-IR tablets. Dissolution testing followed United States Pharmacopeia (USP) guidelines for LEV-XR tablets. Tablets were placed in a buffer solution (pH 6.0) and agitated at 100 rpm. Samples were collected at 0, 0.5, 2, 4, 6, and 8 h, then analyzed by high-pressure liquid chromatography (HPLC) using a USP reference standard. Results indicated that splitting LEV-XR tablets slightly increased drug release compared to intact tablets, while crushing eliminated extended-release properties, mimicking LEV-IR dissolution. These findings suggest that splitting LEV-XR tablets may be a viable strategy for dosing small dogs without compromising sustained release. Conversely, crushing LEV-XR tablets may be useful for rapid drug release in cluster seizure protocols. Future pharmacokinetic studies are needed to confirm if these in vitro results correlate with in vivo performance for both maintenance and emergency seizure management in dogs.

  PublisherOA PDFDOI

• Characterization of post-ictal clinical signs in dogs with idiopathic epilepsy: A questionnaire-based study

  Journal of Veterinary Internal Medicine · 2025-01-01

  articleOpen accessSenior author

  BACKGROUND: Post-ictal (PI) clinical signs are a key defining stage of seizure manifestation in dogs. However, this phase remains poorly understood. OBJECTIVES: To further characterize PI signs and their relation to other parts of a seizure, and understand the owner's perception of how PI signs affect the quality of life (QOL) of the dog. ANIMALS: Eight-seven dogs with a diagnosis of idiopathic epilepsy from a single institution. METHODS: The prospective questionnaire-based study surveying owners of dogs previously and newly diagnosed with idiopathic epilepsy. RESULTS: Post-ictal signs were identified in 79/87 dogs, 5/5 of dogs with focal seizures and 74/82 of dogs with generalized seizures. Median duration of PI signs was 30 minutes (range, 5-4320 minutes). The most common PI signs reported were disorientation (50/79) and wobbliness or clumsiness (49/79). Within a year, a change in PI signs was seen in 18/79 dogs. The administration of benzodiazepines was significantly associated with an increase in duration of PI signs (P = .04). Post-ictal signs had more impact on dogs' quality of life compared with ictal signs (P < .01). Groupings of co-existing PI signs identified included disorientation, blindness and deafness. CONCLUSION: Post-ictal signs are a commonly reported aspect of seizures in dogs with idiopathic epilepsy, both in focal as well as generalized seizures. Co-existence of signs could provide some valuable insight into the relevance of this particular phase of a seizure. Owner-reported signs and documentation emphasize the need for a better understanding of PI signs in dogs with idiopathic epilepsy.

  PublisherDOI

• Case Report: Presumed cerebral salt wasting syndrome in a 10-week-old German Shorthaired Pointer

  Frontiers in Veterinary Science · 2025-03-27

  articleOpen accessCorresponding

  This case report describes a rare presentation of cerebral salt-wasting syndrome (CSW) in a 10-week-old German Shorthaired Pointer following a traumatic brain injury. The patient presented stuporous and tetraplegic with advanced imaging revealing a depressed skull fracture and active brain hemorrhage. Following surgical intervention, the dog exhibited persistent hypovolemia and hyponatremia prompting treatment with intravenous hypertonic saline and enteral sodium supplementation. Positive response to sodium supplementation, coupled with elevated fractional excretion of uric acid (FEUA) despite clinical improvement, supported the diagnosis of CSW. This report contributes novel insights into CSW in veterinary medicine, emphasizing the distinctive features of its presentation, diagnostic considerations, and treatment responses. The clinical utility of FEUA as a diagnostic tool is highlighted for the first time in a canine patient, providing a valuable tool for differentiation. This information enhances veterinary practitioners' awareness, facilitating more accurate diagnoses and tailored treatment strategies for similar cases in the future.

  PublisherOA PDFDOI

• An Exploratory Study on the Relationship Between Idiopathic Epilepsy and Sleep in Dogs

  Journal of Veterinary Internal Medicine · 2025-03-01 · 1 citations

  articleOpen accessSenior authorCorresponding

  BACKGROUND: The bidirectional relationship between epilepsy and sleep is well characterized in humans but has not been thoroughly explored in dogs. OBJECTIVE: Evaluate sleep differences between dogs with idiopathic epilepsy and healthy controls and determine associations among epilepsy characteristics, antiseizure medications (ASMs), and sleep. ANIMALS: Sixty-four dogs with idiopathic epilepsy and 64 non-epileptic control dogs matched by age, breed, and sex. METHODS: Owners of all dogs completed an online survey that included questions regarding signalment, epilepsy history if applicable, and sleep. Owners of epileptic dogs were asked whether their dogs experienced changes in sleep after a seizure. Sleep scores were calculated using the Sleep and Nighttime Restlessness Evaluation (SNoRE) questionnaire, consisting of two factors: "sleep quality" and "sleep interruptions caused by dreaming." Data were analyzed for differences in sleep scores between epileptic and control dogs and any effects of seizure frequency, cluster seizures, and ASMs. RESULTS: Significant differences in sleep scores were identified between epileptic dogs and controls (median, 12 vs. 8, respectively; p < 0.001), driven by poorer sleep quality in the epileptic group. No significant associations were found between sleep scores and seizure frequency, clusters, or ASM use. Fifty-nine percent of dog owners noticed changes in sleep patterns after a seizure, most often increased sleep duration. CONCLUSIONS AND CLINICAL IMPORTANCE: Dogs with idiopathic epilepsy experience negative changes in sleep, emphasizing the importance of monitoring and managing sleep disturbances in this cohort. Larger, multicenter studies controlling for confounding factors are needed to better understand the impact of epilepsy on sleep.

  PublisherOA PDFDOI

• Case Report: 3D-CISS and PC-MRI in the diagnosis and surgical planning of hydrocephalus secondary to presumptive lateral aperture obstruction in a dog

  Frontiers in Veterinary Science · 2025-10-10

  articleOpen access

  Introduction: This report describes the use of three-dimensional constructive interference in steady state (3D-CISS) and phase-contrast magnetic resonance imaging (PC-MRI) sequences to investigate the etiology of severe hydrocephalus, and the subsequent surgical management and long-term outcome. Case presentation: A 5-month-old male Rhodesian Ridgeback presented with acute, progressive neurological signs culminating in non-ambulatory tetraparesis. Clinical and imaging findings were consistent with non-communicating tetraventricular hydrocephalus with concurrent severe syringomyelia, but conventional MRI failed to identify the cause of cerebrospinal fluid (CSF) flow obstruction. Following failure of medical management, advanced MRI sequences were performed to clarify the underlying etiology and guide surgical planning. These included 3D-CISS for high-resolution anatomical assessment and PC-MRI for dynamic evaluation of CSF flow. The findings demonstrated patent intraventricular CSF flow and no evidence of arachnoid septations within the fourth ventricle, thereby excluding a fourth ventricle arachnoid diverticulum. Instead, the imaging findings supported a presumptive diagnosis of hydrocephalus secondary to lateral aperture occlusion. A ventriculoperitoneal (VP) shunt was placed, resulting in substantial clinical improvement, although mild residual cerebellar deficits persisted. Five months later, the dog experienced acute deterioration. Computed tomography revealed fracture of the distal catheter at the level of its abdominal wall anchoring site, likely due to progressive tension as the dog grew, resulting in the catheter snapping into two segments. Revision surgery restored CSF diversion and led to rapid clinical recovery. The patient remains neurologically stable at 28 months of age, 15 months post-revision. Conclusion: Advanced MRI sequences, particularly 3D-CISS and PC-MRI, were instrumental in supporting the presumptive diagnosis of lateral aperture obstruction as the underlying cause of hydrocephalus and in guiding an individualized, effective surgical strategy. This case highlights the diagnostic and clinical value of advanced MRI techniques in managing complex hydrocephalus.

  PublisherOA PDFDOI

• Clinical and imaging findings in dogs with nerve root signature associated with cervical intervertebral disc herniation

  Journal of Veterinary Internal Medicine · 2024-01-12 · 11 citations

  articleOpen accessSenior authorCorresponding

  BACKGROUND: Intervertebral disc herniation (IVDH) is the most common spinal cord disease in dogs. Little information is available regarding the clinical presentation of nerve root signature (NRS) associated with cervical IVDH. HYPOTHESIS/OBJECTIVE: To detail the clinical and magnetic resonance imaging (MRI) findings in dogs with NRS associated with cervical IVDH. ANIMALS: Forty-seven client-owned dogs presenting with thoracic limb NRS and MRI confirmed IVDH. METHODS: Medical records from 2010 to 2020 were retrospectively reviewed for dogs that met inclusion criteria. Imaging studies were evaluated by 2 individuals to characterize location and severity of neural tissue compression. RESULTS: Chondrodystrophoid dogs comprised the majority of the study cohort, with dachshund the most common breed (n = 10). Three-quarters of dogs were ≥7 years of age. Interobserver agreement was moderate or good for all of the imaging variables evaluated. The C6-C7 intervertebral disc space was significantly overrepresented (P = .01), comprising 32% (15/47) of the affected discs. However, 42% (20/47) of cases involved C2-C3 though C4-C5 disc sites. Disc material was more frequently located laterally compared to medially within the vertebral canal (P = .0005), and to be associated with compression of the nerve root at the level of the intervertebral foramen (P = .012). CONCLUSION/CLINICAL IMPORTANCE: NRS is most commonly associated with lateralized or foraminal cervical disc herniations. It is most prevalent with C6-C7 intervertebral disc involvement, suggesting that there might be unique anatomic factors that contribute to development of NRS at this site, but can be a clinical manifestation of IVDH occurring anywhere along the cervical spine.

  PublisherOA PDFDOI

• Pharmacokinetics of subcutaneous ketamine administration via the Omnipod® system in dogs

  Journal of Veterinary Pharmacology and Therapeutics · 2024-03-27 · 1 citations

  articleOpen access

  Ketamine is an injectable anesthetic agent with analgesic and antidepressant effects that can prevent maladaptive pain. Ketamine is metabolized by the liver into norketamine, an active metabolite. Prior rodent studies have suggested that norketamine is thought to contribute up to 30% of ketamine's analgesic effect. Ketamine is usually administered as an intravenous (IV) bolus injection or continuous rate infusion (CRI) but can be administered subcutaneously (SC) and intramuscularly (IM). The Omnipod® is a wireless, subcutaneous insulin delivery device that adheres to the skin and delivers insulin as an SC CRI. The Omnipod® was used in dogs for postoperative administration of ketamine as a 1 mg/kg infusion bolus (IB) over 1 hour (h). Pharmacokinetics (PK) showed plasma ketamine concentrations between 42 and 326.1 ng/mL. The median peak plasma concentration was 79.5 (41.9-326.1) ng/mL with a Tmax of 60 (30-75) min. After the same infusion bolus, the corresponding norketamine PK showed plasma drug concentrations between 22.0 and 64.8 ng/mL. The median peak plasma concentration was 43.0 (26.1-71.8) ng/mL with a median Tmax of 75 min. The median peak ketamine plasma concentration exceeded 100 ng/mL in dogs for less than 1 h post infusion. The Omnipod® system successfully delivered subcutaneous ketamine to dogs in the postoperatively.

  PublisherOA PDFDOI

• ACVIM Consensus Statement on the management of status epilepticus and cluster seizures in dogs and cats

  Journal of Veterinary Internal Medicine · 2023-11-03 · 24 citations

  articleOpen access

  BACKGROUND: Seizure emergencies (ie, status epilepticus [SE] and cluster seizures [CS]), are common challenging disorders with complex pathophysiology, rapidly progressive drug-resistant and self-sustaining character, and high morbidity and mortality. Current treatment approaches are characterized by considerable variations, but official guidelines are lacking. OBJECTIVES: To establish evidence-based guidelines and an agreement among board-certified specialists for the appropriate management of SE and CS in dogs and cats. ANIMALS: None. MATERIALS AND METHODS: A panel of 5 specialists was formed to assess and summarize evidence in the peer-reviewed literature with the aim to establish consensus clinical recommendations. Evidence from veterinary pharmacokinetic studies, basic research, and human medicine also was used to support the panel's recommendations, especially for the interventions where veterinary clinical evidence was lacking. RESULTS: The majority of the evidence was on the first-line management (ie, benzodiazepines and their various administration routes) in both species. Overall, there was less evidence available on the management of emergency seizure disorders in cats in contrast to dogs. Most recommendations made by the panel were supported by a combination of a moderate level of veterinary clinical evidence and pharmacokinetic data as well as studies in humans and basic research studies. CONCLUSIONS AND CLINICAL RELEVANCE: Successful management of seizure emergencies should include an early, rapid, and stage-based treatment approach consisting of interventions with moderate to preferably high ACVIM recommendations; management of complications and underlying causes related to seizure emergencies should accompany antiseizure medications.

  PublisherOA PDFDOI

Frequent coauthors

• Natasha J. Olby

  North Central State College

  76 shared

• Peter J. Early

  North Carolina State University

  45 shared

• Christopher L. Mariani

  North Carolina State University

  37 shared

• Nicholas Sharp

  Nvidia (United States)

  34 shared

• Luisa De Risio

  Animal Health Trust

  24 shared

• Holger A. Volk

  University of Veterinary Medicine Hannover, Foundation

  16 shared

• Simon R. Platt

  15 shared

• Todd M. Skeen

  Carolina Veterinary Specialists

  14 shared

Labs

• CVM: Spontaneous Animal Disease ModelsPI

Education

• Ph.D., Animal Science

  University of California, Davis

  2002

• M.S., Animal Science

  University of California, Davis

  1998

• B.S., Animal Science

  University of California, Davis

  1996

Awards & honors

• Member, International Veterinary Epilepsy Task Force
• Diplomate, American College of Veterinary Internal Medicine…
• Nettifee Named American Humane Veterinary Nurse Hero of the…