About

Adam Birkenheuer is a faculty member associated with the College of Veterinary Medicine at NC State University. The page text does not provide specific details about his research focus, background, or key contributions. Therefore, no detailed biography information is available from the provided content.

Research topics

• Medicine
• Internal medicine
• Biology
• Anesthesia
• Virology
• Veterinary medicine
• Genetics
• Radiology
• Pathology
• Gastroenterology
• Nuclear medicine
• Urology
• Ecology
• Surgery
• Zoology
• Anatomy

Selected publications

• Factors influencing insulin prescribing practices among small animal specialists

  Frontiers in Veterinary Science · 2026-05-21

  articleOpen accessSenior author

  Initial management of diabetic ketoacidosis (DKA) often involves administration of regular insulin, and the transition from regular to intermediate or long-acting insulin can be challenging. While some guidelines exist for this, recent developments in the field have altered the diabetes treatment landscape. The objective of this study was to describe insulin prescribing practices of small animal specialists for patients with DKA and to explore the factors influencing the selection of insulin type and dose. An electronic survey involving two clinical case scenarios was distributed to diplomates of American College of Veterinary Internal Medicine (ACVIM) and American College of Veterinary Emergency and Critical Care (ACVECC) in Spring 2025. For the canine case, 76/162 participants (47%) selected insulin lente (Vetsulin ® or Caninsulin), with 74/162 (46%) selecting insulin lente administered twice daily (BID). The median dose for insulin lente BID was 0.43 U/kg/injection (range, 0.05–1.29 U/kg/injection). 62 out of 162 respondents (38%) selected insulin NPH (Humulin ® -N, Novolin ® -N) BID at a median dose of 0.43 U/kg/injection (range, 0.11–2.15 U/kg/injection). For the feline case, 120/151 participants (79%) selected insulin glargine 100 U/ml, with 118/151 (78%) selecting insulin glargine BID. The median dose for insulin glargine BID was 0.17 U/kg/injection (range, 0.04–1.87 U/kg/injection). The survey data describe current prescribing practices and clinical decision-making. As options for novel insulins and diabetic therapies expand, additional studies focused on outcomes related to clinical control, cost efficacy, and quality-of-life for pet and owner are needed.

  PublisherOA PDFDOI

• Utility of ChatGPT in generating accurate client handouts for common veterinary internal medicine diseases

  Journal of Veterinary Internal Medicine · 2026-01-01

  articleOpen access

  BACKGROUND: Chat Generative Pre-trained Transformer's (ChatGPT) ability to generate client educational materials for use in practice is unknown. HYPOTHESIS/OBJECTIVES: To assess the educational quality of ChatGPT-generated client handouts for common internal medicine diseases. We hypothesized that ChatGPT can be used to efficiently generate easy-to-understand, accurate handouts for client education. ANIMALS: Small Animal Internal Medicine (SAIM) diplomates and pet owners were administered 2 separate electronic surveys. METHODS: Client handouts on diabetes mellitus (DM) and immune-mediated hemolytic anemia (IMHA) in dogs and inflammatory bowel disease (IBD) in cats were generated by using a standardized prompt in ChatGPT-3.5. Electronic surveys were distributed to both pet owners and American College of Veterinary Internal Medicine (ACVIM)-SAIM diplomates. RESULTS: Pet owners (n = 50) reported a greater understanding of each disease process after reading the handouts for DM (Z = 5.865, P < .001), IMHA (Z = 5.953, P < .001), and IBD (Z = 5.508, P < .001). Median pet owner satisfaction scores (reported on a scale of 0 to 5, with 0 indicating poor satisfaction and 5 indicating maximal satisfaction) were 4 for DM, 4 for IMHA, and 5 for IBD. Many diplomates reported that they would use the handout on DM (n = 48/67; 71%), IBD (n = 47/62; 76%), and IMHA (n = 32/64; 50%) with either "minor" or "minimal to no" revisions. CONCLUSIONS AND CLINICAL IMPORTANCE: Although some refinement is warranted, ChatGPT-3.5 was able to successfully generate client educational handouts for common internal medicine diseases.

  PublisherOA PDFDOI

• Isolation and Characterization of <i>Rickettsia finnyi</i> , Novel Pathogenic Spotted Fever Group <i>Rickettsia</i> in Dogs, United States

  Emerging infectious diseases · 2025-11-01

  articleOpen access

  I n 2020, a unique spotted fever group Rickettsia (SFGR), Rickettsia sp.2019-CO-FNY, was identified in 3 clinically ill dogs in the southern and midwestern United States (1).Those dogs exhibited symptoms like those caused by R. rickettsii, the agent responsible for Rocky Mountain spotted fever (RMSF).SFGR are emerging tickborne pathogens infecting dogs and humans.Among tickborne pathogens infecting dogs, SFGR had the highest seroprevalence at 10.4% in the United States during 2004-2010 (2).The Centers for Disease Control and Prevention reported annual SFGR cases in humans in the United States increased substantially from 486 in 2000 to 6,248 in 2017 (3).Despite frequent exposure to SFGR, gaps remain in our understanding of pathogenic Rickettsia spp., disease severity, and tick vectors.In the United States, several SFGR species, including R. parkeri, R. rickettsii, and R. rickettsii subsp.californica, cause disease in humans (4,5).Among those species, R. rickettsii is the most virulent in dogs and humans and can be fatal without early antibiotic intervention (6).In addition to R. rickettsii, other SFGR species have been detected in dogs in the United States, including R. montanensis, R. amblyommatis, and R. parkeri, all of which caused asymptomatic infection (7,8).Until recently, R. rickettsii was the only SFGR known to cause disease in dogs in North America.Dogs with RMSF can demonstrate fever, lethargy, neurologic signs, and generalized or localized pain, like arthropathy (9,10).Clinical signs reported in dogs infected with Rickettsia sp.2019-CO-FNY resembled those seen in RMSF, indicating the existence of additional virulent SFGR in the United States and underscoring the importance of expanded vectorborne disease surveillance for canine and human health.In this study, we cultured and sequenced a novel, pathogenic SFGR, Rickettsia sp.2019-CO-FNY.We identified Rickettsia sp.2019-CO-FNY in 14 additional sick dogs and cultured it from 1 infected dog.On the basis of whole-genome sequencing (WGS) and imaging, we determined that Rickettsia sp.2019-CO-FNY is a new Rickettsia species, which we propose naming Rickettsia finnyi sp.nov., strain 2024-CO-Wats.

  PublisherOA PDFDOI

• Response to Correspondence on ‘Analysis of US Marketed Artemisinin Supplements for Use in Dogs’

  Journal of Veterinary Pharmacology and Therapeutics · 2024-10-14

  letterOpen access
  PublisherOA PDFDOI

• Case report: Severe hepatopathy following rivaroxaban administration in a dog

  Frontiers in Veterinary Science · 2024

  • Medicine
  • Internal medicine
  • Anesthesia

  Rivaroxaban, a specific factor Xa inhibitor and commonly utilized anticoagulant, has been known to cause hepatotoxicity and liver failure in humans. Although rivaroxaban is frequently used in veterinary medicine, hepatotoxicity has not been previously reported in dogs. The current case report describes a dog that developed severe hepatopathy following rivaroxaban administration for a large right pulmonary artery thrombus. An estimated 6-year-old spayed female mixed-breed dog developed anorexia and lethargy 9 days after rivaroxaban administration began. Subsequent labwork revealed severe hepatocellular hepatopathy, and rivaroxaban was discontinued. Additional diagnostics did not reveal an underlying etiology, although hepatic cytology could be consistent with a toxic injury. The hepatopathy and clinical signs improved after rivaroxaban was discontinued. The time to onset, type of hepatopathy, and time to resolution were all similar to those reported for human cases. This case provides precedence to advocate for improved and closer monitoring of dogs receiving factor Xa inhibitors. In cases of suspected hepatotoxicity with no other identifiable cause, a risk-benefit analysis should be performed, and discontinuation of rivaroxaban administration or alternative anticoagulant medications should be considered.

  PublisherOA PDFDOI

• Analysis of US Marketed Artemisinin Supplements for Use in Dogs

  Journal of Veterinary Pharmacology and Therapeutics · 2024-08-24 · 3 citations

  articleOpen access

  Oral artemisinin has antiparasitic activity and may help improve treatment success rates in dogs infected with Babesia gibsoni. However, these artemisinin products are unapproved and unregulated botanical supplements. They have not been evaluated for safety and efficacy or for strength, purity, or quality compared with a reference standard. Before considering these products for a clinical study, we evaluated the strength of four suppliers of artemisinin capsules using an high-performance liquid chromatography method validated in our laboratory. We found that the four artemisinin-labeled products that were tested had high within product and between product variability in capsule strength compared with the stated capsule strength on the product label. No products met the acceptance criteria of the United States Pharmacopeia and International Council for Harmonisation (ICH) as well as the criteria adapted by the authors. One product had no detectable artemisinin, and the other three products were much higher than the stated label strength. The results of this study reinforce the importance of testing unapproved and unregulated supplements before recommending a supplement for clinical use in dogs.

  PublisherOA PDFDOI

• ACVIM consensus statement on the diagnosis of immune thrombocytopenia in dogs and cats

  Journal of Veterinary Internal Medicine · 2024-05-16 · 29 citations

  articleOpen access

  Immune thrombocytopenia (ITP) is the most common acquired primary hemostatic disorder in dogs. Immune thrombocytopenia less commonly affects cats but is an important cause of mortality and treatment-associated morbidity in both species. Immune thrombocytopenia remains a diagnosis of exclusion for which diagnostic guidelines are lacking. Primary, or non-associative, ITP refers to autoimmune platelet destruction. Secondary, or associative, ITP arises in response to an underlying disease trigger. However, evidence for which comorbidities serve as ITP triggers has not been systematically evaluated. To identify key diagnostic steps for ITP and important comorbidities associated with secondary ITP, we developed 12 Population Evaluation/Exposure Comparison Outcome (PECO) format questions. These questions were addressed by evidence evaluators utilizing a literature pool of 287 articles identified by the panelists using a structured search strategy. Evidence evaluators, using panel-designed templates and data extraction tools, summarized evidence and created guideline recommendations that then were integrated by diagnosis and comorbidity domain chairs. The revised PECO responses underwent a Delphi survey process to reach consensus on final guidelines. A combination of panel expertise and PECO responses were employed to develop algorithms for diagnosis of ITP in dogs and cats, which also underwent 4 iterations of Delphi review. Comorbidity evidence evaluators employed an integrated measure of evidence (IME) tool to determine evidence quality for each comorbidity; IME values combined with evidence summaries for each comorbidity were integrated to develop ITP screening recommendations, which also were subjected to Delphi review. Commentary was solicited from multiple relevant professional organizations before finalizing the consensus. The final consensus statement provides clinical guidelines for the diagnosis of, and underlying disease screening for, ITP in dogs and cats. The systematic consensus process identified numerous knowledge gaps that should guide future studies. This statement is a companion manuscript to the ACVIM Consensus Statement on the Treatment of Immune Thrombocytopenia.

  PublisherOA PDFDOI

• Transmission of Cytauxzoon felis by injection of Amblyomma americanum salivary glands

  Parasitology International · 2023-04-20 · 2 citations

  articleOpen accessSenior authorCorresponding

  BACKGROUND: Cytauxzoonosis is a life-threatening disease of cats, caused by the tick-borne piroplasmid hemoparasite, Cytauxzoon felis. Current experimental models for cytauxzoonosis rely on either tick transmission or direct injection of infected cat tissues. These models require researchers to directly work with infected ticks or use cats with acute cytauxzoonosis. To improve the feasibility and accessibility, there is a need to establish sharable resources among researchers. In related piroplasmid parasites, sporozoite-based inoculums are routinely produced from tick salivary glands, cryopreserved and distributed to other investigators and facilities. For these parasites, sporozoites have been the basis for vaccine development and in vitro cultivation, both of which remain lacking for C. felis research. If infectious sporozoites can be similarly isolated for C. felis, it would significantly broaden our capabilities to study this parasite. Aims of this study was to determine if C. felis sporozoites inoculums collected from the salivary glands of Amblyomma americanum ticks were capable of inducing cytauxzoonosis in naïve cats. MATERIALS AND METHODS: A. americanum nymphs were acquisition-fed on a donor cat chronically infected with C. felis and allowed to molt to adults. Four groups of adult ticks (n = 50/group) were either stimulation-fed for 4 days on naïve cats or were heated at 37 °C for 4 days. After these treatments, salivary glands (SG) of each group of ticks were collected to create inoculums. Infectivity of these inoculums was then tested by subcutaneous injection into naïve cats. RESULTS: The two naïve cats used for stimulation feeding and as controls both developed cytauxzoonosis, indicating these groups of ticks were capable of producing infectious sporozoites. Of the 2 cats that were injected with SGs from the stimulation-fed ticks, one cat developed cytauxzoonosis and C. felis infection was confirmed by both light microscopy and PCR. The other cat did not develop cytauxzoonosis and only had equivocal evidence of infection. Neither cat injected with SGs from the heated ticks developed cytauxzoonosis. One of these cats had equivocal evidence of infection and one had no evidence of infection. CONCLUSION: This study validates the feasibility of collecting infectious sporozoites from C. felis-infected ticks that can be used to infect naïve cats. While this model requires further optimization, it has the potential to expand resources to study C. felis and further advance research in this field.

  PublisherDOI

• A practical protocol to prepare paraffin-embedded whole tick histology sections

  Ticks and Tick-borne Diseases · 2023-03-23 · 3 citations

  articleOpen accessSenior authorCorresponding

  Ticks are important ectoparasites that are capable of transmitting multiple classes of pathogens and are currently linked with many emerging tick-borne diseases worldwide. With increasing occurrences of tick-borne diseases in both humans and veterinary species, there is a continuous need to further our understanding of ticks and the pathogens they transmit. Whole tick histology provides a full scope of the tick internal anatomy, allowing researchers to examine multiple organs of interest in a single section. This is in contrast to other techniques that are more commonly utilized in tick-borne disease research, such as electron microscopy and light microscopy of individual organs. There is a lack of literature describing a practical technique to process whole tick histologic sections. Therefore, the current study aims to provide researchers with a workable protocol to prepare high quality paraffin-embedded whole tick histology sections. Amblyomma americanum adults were used as an example species for this study. After a series of pilot experiments using a combination of various fixatives, softening agents and processing techniques, we elected to compare two common fixatives, 10% neutral-buffered formalin (NBF) and Bouin's solution for whole ticks. Equal numbers of A. americanum unfed adults (n = 10/fixative) were processed identically and their whole tick histology coronal sections were individually scored. Higher scores were assigned to whole tick sections that contained more internal organs that are crucial for tick-borne disease research (e.g. salivary glands and midgut), high integrity of tissues and exoskeleton on the section, and good fixation and staining quality of the tissues. The mean total scores for Bouin's-fixed ticks were significantly higher compared to NBF-fixed ticks (p = 0.001). To further assess our preferred technique, we also demonstrated the feasibility of producing high quality whole tick sections for three other common tick species of medical importance (Rhipicephalus sanguineus, Ixodes scapularis, and Dermacentor variabilis) using Bouin's solution. While this technique may require further optimization for other tick species, we described a feasible protocol that uses commonly available tools, reagents and standard histologic equipment. This should allow any investigator to easily make adjustments to this protocol as needed based on their experimental goals.

  PublisherDOI

• A Novel Vaccine Strategy to Prevent Cytauxzoonosis in Domestic Cats

  Vaccines · 2023-03-02 · 2 citations

  articleOpen access

  Cytauxzoonosis is caused by Cytauxzoon felis (C. felis), a tick-borne parasite that causes severe disease in domestic cats in the United States. Currently, there is no vaccine to prevent this fatal disease, as traditional vaccine development strategies have been limited by the inability to culture this parasite in vitro. Here, we used a replication-defective human adenoviral vector (AdHu5) to deliver C. felis-specific immunogenic antigens and induce a cell-mediated and humoral immune response in cats. Cats (n = 6 per group) received either the vaccine or placebo in two doses, 4 weeks apart, followed by experimental challenge with C. felis at 5 weeks post-second dose. While the vaccine induced significant cell-mediated and humoral immune responses in immunized cats, it did not ultimately prevent infection with C. felis. However, immunization significantly delayed the onset of clinical signs and reduced febrility during C. felis infection. This AdHu5 vaccine platform shows promising results as a vaccination strategy against cytauxzoonosis.

  PublisherOA PDFDOI

Frequent coauthors

• Leah A. Cohn

  Missouri College

  49 shared

• Henry S. Marr

  41 shared

• Edward B. Breitschwerdt

  North Carolina State University

  35 shared

• Michael G. Levy

  31 shared

• Megan E. Downey

  North Carolina State University

  18 shared

• Margaret A. Booth-Sayer

  Carolina Veterinary Specialists

  16 shared

• Sonya G. Gordon

  Texas A&M University

  16 shared

• Marlyn S. Whitney

  University of Missouri

  16 shared

Awards & honors

• Andy Quattlebaum Distinguished Chair in Infectious Disease R…
• Diplomate, American College of Veterinary Internal Medicine