Michelle M Dennis

• DVM, PhD, DACVP
• Professor (Associate) at University of Tennessee College of Veterinary Medicine

Coyotes are exposed to many parasites and pathogens of veterinary and zoonotic concern. To assess the prevalence of the diseases caused by these microbes, we opportunistically obtained coyote samples from a variety of sources including a GPS collaring study, rabies testing facilities, wildlife resources agents, and road-side mortalities. We perform...

Many taxa around the globe are threatened by often unexplained mass mortality events (MMEs), which can decimate populations and compromise key ecosystem functions. One example of a highly threatened taxon facing frequent MMEs is freshwater mussels (Unionida). There has been a recent increase in interest in understanding the causes of freshwater mus...

Collection of coral for histologic examination requires holding of samples in seawater for a time before they are fixed for histologic processing. This could adversely affect the interpretation of morphologic changes during histologic examinations. We evaluated the microscopic morphology of Porites evermanni and Montipora capitata held (0–120 minut...

Babesia is a diverse genus of piroplasms that parasitize the red blood cells of a wide variety of mammals and avian species, including humans. There is a lack of knowledge on the Babesia species of carnivores and mesomammals in the eastern United States and the potential impacts of these species on the health of humans and domestic animals. We surv...

Freshwater mussels are integral components of riverine ecosystems, influencing water quality, nutrient cycling, and habitat characteristics. Enigmatic freshwater mussel declines, often characterized by sudden mass mortality events, pose significant challenges to conservation efforts. The Clinch River, a freshwater biodiversity hotspot in Virginia a...

Five adult Greater Caribbean manatees Trichechus manatus manatus were found stranded on various coasts of Puerto Rico; 2 stranded alive and 3 stranded dead. Clinical signs observed in live-stranded manatees included emaciation, weakness, bradypnea, arrhythmia, and nasal mucus discharge. Postmortem examinations revealed serosanguinous, mucohemorrhag...

Simple Summary This case report highlights two wild juvenile American black bears that were admitted to a rehabilitation facility but were euthanized due to severe immobility and joint laxity. Known musculoskeletal diseases of young bears are usually caused by trauma in the wild, or potentially rickets (a form of malnutrition) if raised in captivit...

Freshwater mussels are integral components of riverine ecosystems, influencing water quality, nutrient cycling, and habitat characteristics. Enigmatic freshwater mussel declines, often characterized by sudden mass mortality events, pose significant challenges to conservation efforts. The Clinch River, a freshwater biodiversity hotspot, has experien...

West Indian manatees (Trichechus manatus) harbor a variety of endoparasites, including the nasal trematode Pulmonicola cochleotrema, which infects the respiratory tract, especially the nasal passages. Previous studies have described and identified this digenean using morphological data only. This study presents the first molecular identification of...

In the last decades, there has been a concerning increase in the frequency and severity of coral disease outbreaks on a global scale, resulting in significant damage to the coral reef ecosystem and biodiversity. Growth anomalies (GAs) have been increasingly observed, with significantly higher occurrences in larger and older coral colonies compared...

This retrospective study aimed to characterize and determine the prevalence of spinal disease in nondomestic felids within a sanctuary population. A review of 304 postmortem examination reports in Panthera species from 2003 to 2021 revealed that 86/304 (28%) were diagnosed with spinal disease. Spinal lesions were categorized according to pathologic...

Stony corals (Scleractinia) are in the Phylum Cnidaria (cnidae referring to various types of stinging cells). They may be solitary or colonial, but all secrete an external, supporting aragonite skeleton. Large, colonial members of this phylum are responsible for the accretion of coral reefs in tropical and subtropical waters that form the foundatio...

Freshwater mussels are one of the most imperiled groups of organisms in the world, and more than 30 species have gone extinct in the last century. While habitat alteration and destruction have contributed to the declines, the role of disease in mortality events is unclear. In an effort to involve veterinary pathologists in disease surveillance and...

Aspergillosis of gorgonian sea fans is a Caribbean-wide disease characterized by focal, annular purple pigmentation with central tissue loss. We applied a holistic diagnostic approach including histopathology and a combination of culture and direct molecular identification of fungi to evaluate these lesions with the goal of determining the diversit...

The extinction risk of the whitespotted eagle ray Aetobatus narinari was recently elevated from near-threatened to endangered by the International Union for the Conservation of Nature. However, many aspects of its basic ecology remain poorly understood, hampering efforts to develop meaningful conservation strategies. In this photo-identification st...

Increasing hatchling survival is an important element of conservation of the critically endangered hawksbill sea turtle (Eretmochelys imbricata). Yet, there is little information regarding mortality-associated pathological states of hawksbill hatchlings. The aim of this study was to describe lesions affecting hawksbill hatchlings that died while un...

Climate change is a worldwide health problem. Veterinarians and other health professionals have been called upon to participate in mitigation and adaptation efforts to protect animals and people. The objectives of this article are to review the ways in which climate change impacts animal health and highlight ways in which veterinarians and other an...

Stenella clymene (Clymene Dolphin) is an oceanic endemic species of the Atlantic Ocean, well-documented in the Gulf of Mexico, but mostly unknown from the Caribbean. Here we report on the stranding, rescue, veterinary care, necropsy, and genetic species confirmation of 2 Clymene Dolphins from the Caribbean coast of Colombia in 2018 and 2020. Rescue...

The Antillean manatee (Trichechus manatus manatus) is an endangered species living along the Atlantic coasts of the Americas from Florida, throughout the Caribbean, to Brazil. On July 2020, a manatee with multiple wounds due to boat inflicted trauma was rescued from the coast east of Cayo Mata, Salinas, Puerto Rico. This manatee had neutropenia, le...

Free-ranging American black bears (Ursus americanus) often share habitat with humans and domestic animals, predisposing them to anthropogenic conflicts. Rehabilitation under professional care is a management option for orphaned, injured, and/or ill bears. Across several southeastern states, rescued bears are assessed and treated at the University o...

We report cross-reactive antibodies from prepandemic cats and postpandemic South Carolina white-tailed deer that are specific for that SARS-CoV RBD. There are several potential explanations for this cross-reactivity, each with important implications to coronavirus disease surveillance.

In late 2019, a novel coronavirus began circulating within humans in central China. It was designated SARS-CoV-2 because of its genetic similarities to the 2003 SARS coronavirus (SARS-CoV). Now that SARS-CoV-2 has spread worldwide, there is a risk of it establishing new animal reservoirs and recombination with native circulating coronaviruses. To s...

The Caribbean spiny lobster Panulirus argus , a long-lived decapod crustacean, is fished throughout its geographical range and generates close to 1 billion US dollars annually. Fisheries across this range are fully- or over-exploited, spurring management strategies such as closed seasons and minimum size limitations. The objective of this study was...

Standardization of tumor assessment lays the foundation for validation of grading systems, permits reproducibility of oncologic studies among investigators, and increases confidence in the significance of study results. Currently, there is minimal meth-odological standardization for assessing tumors in veterinary medicine, with few attempts to vali...

Growth anomalies (GAs) are a morphologically diverse and poorly understood group of lesions affecting corals. The aim of this study was to describe the prevalence and morphology of GAs affecting the faviid corals Diploria labyrinthiformis, Pseudodiploria strigosa, Psudodiploria clivosa, and Colpophyillia natans on St. Kitts. Three gross morphologic...

Most members of Echinodermata are dioecious and undergo sexual reproduction, with a few species reproducing asexually. Uniting features of all echinoderms include radial symmetry (pentamerous symmetry), a tricoelomate body cavity, and a body wall composed of calcite endoskeletal plates (dermal ossicles) connected by “mutable collagenous tissue.” Th...

Gastropoda is the largest group in the phylum Mollusca, comprising over 25000 genus‐group names that encompass snails, conch, whelks, cowries, abalone, limpets, slugs, sea hares, and nudibranchs among others. The presence of a well‐defined head and foot, and asymmetric organs, a feature resulting from the unique torsion process that occurs during e...

In this study, we performed comprehensive pathology examinations on 83 Tripneustes ventricosus from 11 locations on St. Kitts to build baseline data necessary for disease diagnosis in this species. Gross abnormalities were observed in 23/83 (28%) urchins and included spine loss, visceral hyperpigmentation, test discoloration, and test ulceration. C...

Equine arytenoid chondritis causes airway obstruction and abnormal upper airway noise due to a space-occupying lesion(s) and decreased abduction. Our objective was to compare clinical scores and ultrasonographic findings with gross and microscopic lesions of naturally occurring arytenoid chondritis, in order to guide surgical treatment. Seventeen n...

Northwest Atlantic leatherback sea turtles (Dermochelys coriacea) are endangered and low hatch success limits potential for population recovery. We examined essential and nonessential metal concentrations in 43 eggs from nests on St. Kitts to determine if there was a relationship with hatch success. Whole homogenized embryos and undeveloped eggs co...

Disease is contributing to the decline of coral reefs globally, but the cause and pathogenesis of most coral diseases are poorly understood. Using Gorgonia ventalina and G. flabellum as a model for coral disease diagnosis, we histologically and microbiologically examined 45 biopsies of lesions resembling Gorgonia multifocal purple spots (MFPS) with...

The Caribbean spiny lobster, Panulirus argus (Latreille, 1804), is an important resource in the Western Atlantic Ocean, Caribbean Sea, and Gulf of Mexico. A nemertean egg predator of P. argus, Carcinonemertes conanobrieni Simpson, Ambrosio & Baeza, 2017, was recorded in Florida in 2017 and Colombia in 2018. This study sought to investigate the pres...

The Caribbean spiny lobster, Panulirus argus (Latreille, 1804) is a highly commercial species and comprises the largest spiny lobster fishery in the world. Although populations have declined throughout its range, there is little known regarding its diseases and pathogens. The objectives of this study were to provide illustrated and standardized met...

The endangered corals Orbicella annularis and O. faveolata are crucial to Caribbean reefs because of their large size and contribution to reef framework. The objective of this study was to describe the prevalence and progression of macroscopically evident lesions affecting Orbicella spp. in shallow fringing reefs in St. Kitts. Cross-sectional surve...

Globally, the hatch success of leatherback sea turtles (Dermochelys coriacea) is much lower than any other sea turtle species. Causes of embryonic mortality, a contributing factor to the low hatch success of the species, are poorly understood. Muscle necrosis, renal mineralization, and bacterial pneumonia are prevalent among embryos and hatchlings...

Melioidosis is an emerging infectious disease of humans and animals caused by the bacterium Burkholderia pseudomallei and endemic in tropical regions, principally Southeast Asia and northern Australia. In September 2017, after Hurricane Maria impacted the Dolphin Discovery facility in the Federation of St. Kitts and Nevis, a juvenile male bottlenos...

We describe the presence of the non-native Pacific ophiuroid species Ophiothela mirabilis on the island of St. Kitts, federation of St. Kitts and Nevis. Individuals were found in various states of asexual reproduction on common Caribbean sea fans (Gorgonia ventalina) at two locations. Definitive identification was based on morphological features an...

Trichuris spp. infections can cause typhlitis or typhlocolitis in many species, but there are no published studies about its pathology in cats. Trichuris sp. infection in cats appears to be rare in most parts of the world but is frequent in some tropical and subtropical regions. The purpose of this study was to describe intestinal lesions associate...

A 4-month-old intact male domestic shorthair kitten living in St Kitts, West Indies presented with respiratory distress, cachexia, and mucopurulent nasal discharge. Thoracic radiographs revealed a diaphragmatic hernia. The diaphragmatic hernia as well as subpleural pulmonary nodules suspicious for verminous pneumonia were identified during a postmo...

Studies of ectoparasites of wild-caught queenfish Scomberoides commersonnianus from several areas in northern Australia were reviewed to investigate relationships between parasite burdens, environmental conditions and external lesions. A sample of 27 queenfish captured near a dredge spoil disposal site in Gladstone Harbour, Queensland, Australia, i...

Queen conch (Lobatus gigas) is a marine gastropod endemic to the Caribbean. This species is a cultural symbol, being a significant local food source and the second largest commercial fishery in the region. However, over-exploitation and natural habitat degradation have exerted high survival pressure on this species. This work aims to provide novel...

Acanthurus spp. of St. Kitts and other Caribbean islands, including ocean surgeonfish A. bahianus, doctorfish A. chirurgus, and blue tang A. coeruleus, frequently show multifocal cutaneous pigmentation. Initial reports from the Leeward Antilles raised suspicion of a parasitic etiology. The aim of this study was to quantify the prevalence of the dis...

Background Four species of Strongyloides, Strongyloides felis, Strongyloides planiceps, Strongyloides stercoralis and Strongyloides tumefaciens, have been identified in cats based on morphology and location in the host with limited data on the prevalence and disease potential of these different species. Strongyloides tumefaciens adults are located...

Sustained hatchling production is a priority for leatherback sea turtle (Dermochelys coriacea) conservation. Yet the species is challenged by notoriously low hatch success, much lower than other species of sea turtles, and the result of a high rate of embryo mortality for which the causes are not understood. The aim of our study was to describe the...

The queen conch Lobatus gigas is the second largest commercial fishery in the Caribbean, and overharvesting has resulted in significant population declines. Depleted populations are at greater risk of stochastic events, including disease epidemics; however, disease diagnosis in L. gigas has been limited by the lack of standard procedure and histolo...

Unusual inclusion bodies occur within the epithelial cells of the digestive gland of queen conch, Lobatus gigas, and have previously been described as apicomplexan parasites. The aim of this study was to investigate the parasitic features of these inclusion bodies in queen conch. L. gigas from St. Kitts (Caribbean Sea) consistently (100% of n = 61)...

Queen conch, Lobatus gigas, are one of the largest commercial fisheries in the Caribbean and are severely depleted due to overharvesting. Dwindling and fragmented populations are at high risk to stochastic events such as disease epidemics; however, there is a paucity of literature regarding queen conch disease. A histopathological survey was conduc...

Introduction. Leptospirosis is a zoonotic bacterial disease of global distribution affecting humans and animals. The initial phase of leptospirosis resembles many other febrile illness and due to its broad and biphasic clinical manifestations, selection and implementation of appropriate diagnostic tests can be challenging. Case presentation. This r...

A 10-year-old female mixed-breed dog presented for acute dyspnoea developing nine months after multiple mammary tumours were identified. The dog was euthanased and postmortem examination revealed widespread embryonal rhabdomyosarcoma of the myotubular variant involving the largest mammary tumour, the spleen, kidney, liver, lung and heart. The diagn...

The aim of this study was to describe two epizootics of high mortalities from infection with Streptococcus agalactiae, occurring in captive rays held in a marine display aquarium in south-east Queensland, Australia, in 2009 and 2010. Five different species of rays were affected, including mangrove whiprays (Himantura granulata), estuary rays (Dasya...

In recent years, an emergent Klebsiella pneumoniae hypermucoviscous (HMV) phenotype has been associated with increased invasiveness and pathogenicity in primates. The HMV phenotype is characterized by different capsular serotypes, associated with several genes including the rmpA (regulator of mucoid phenotype) and magA (mucoviscosity-associated) ge...

Case summary A case of cerebral phaeohyphomycosis caused by Cladophialophora bantiana is described in a 15-week-old domestic shorthair kitten. Relevance and novel information Cerebral phaeohyphomycosis is a rare condition in cats caused by dematiaceous fungi. This report describes the clinical and histopathological findings in the youngest case do...

Streptococcus agalactiae, the aetiological agent of streptococcosis in fish, is an important pathogen of cultured and wild fish worldwide. To gain a better understanding of the pathogenesis of streptococcosis in Nile tilapia (Oreochromis niloticus), and to identify the experimental route of infection that most closely mimics natural disease, finger...

The objective of this study was to assess the extent and describe the nature of a multispecies marine finfish and crustacean disease event that occurred in Gladstone Harbour, Australia, 2011-2012. Finfish were examined for this study in January to April 2012 from sites where diseased animals were previously observed by the public. Gross abnormaliti...

BACKGROUND: Squamous cell carcinomas (SCC) are uncommon in reptiles and there have been few reports of neoplasia in Australian crocodiles, despite increased numbers being raised in captivity. CASE REPORT: We report a locally invasive SCC in the hindlimb of a wild-caught saltwater crocodile (Crocodylus porosus) with hepatic metastasis. The gross ap...

Soft tissue sarcomas (STSs) are locally invasive and surgery with or without radiation therapy is the current standard of care in dogs. Typical protocols for treating incompletely excised STSs involve curative intent radiation with total dose in excess of 50 Gy. Forty-eight dogs with histologically confirmed incomplete or closely excised STSs were...

Case reportA 2-month-old Standardbred filly was presented for examination and treatment of extensive congenital skin lesions that had a linear distribution on the left front leg extending from the dorsal midline to the metacarpal region.The lesions were surgically excised under general anaesthesia.Surgical excision was curative and there were no si...

A retrospective study evaluated the clinical data and histologic features of non-neoplastic dermatologic lesions in skin biopsies from horses, donkeys, and mules submitted over a 10-year period to the Colorado State University Diagnostic Medicine Center and to the University of Saskatchewan Western College of Veterinary Medicine and Prairie Diagnos...

Objective: To identify epidemiological trends in cutaneous neoplasms affecting equids in central North America and compare them with previously reported trends. Design: Retrospective case series. Sample: 3,351 cutaneous biopsy specimens from 3,272 equids with a neoplastic diagnosis. Procedures: Diagnostic reports from 2 diagnostic laboratori...

The objective of this study was to determine the prevalence of angiostrongylosis in tawny frogmouths (Podargus strigoides) and brushtail possums (Trichosurus vulpecula) with signs of neurological disease, and to describe the clinicopathological features of angiostrongylosis in both species. Tawny frogmouths and brushtail possums with signs of neuro...

During meat inspection, unusual pigmented lesions were found in the abdomens of 411 sheep from a flock raised in the Northern Tablelands of New South Wales. In each affected sheep there were multiple discrete, soft, yellow homogeneous plaques beneath the parietal peritoneum and extending into marginating facial planes of the diaphragm and body wall...

The objective of this study was to describe chronological changes in infection status and enteric lesions of sheep naturally exposed to Mycobacterium avium subspecies paratubercuolosis. Samples of terminal ileum (TI) and mesenteric lymph node (MLN) were collected from 77 Merino sheep via surgical biopsy at 12, 18, and 24 months of age and necropsy...

The objective of this study was to describe the frequency of histopathological lesions and categorize histopathologically evident infections in sick ornamental fish from pet shops in New South Wales, Australia. We examined 108 fish that had evidence of morbidity or mortality, including 67 cyprinids, 25 osphronemids, 11 poeciliids, 4 characids and 1...

Protozoa morphologically consistent with Cryptosporidium sp. were histologically-evident in the stomach of three cohorts of Murray cod (Maccullochella peelii peelii) from a single aquaculture facility in Australia. One cohort was asymptomatic. A second cohort had shown low-level mortalities, reduced appetite, and slowed growth, and fluid distension...

Two outbreaks of mortality in juvenile barramundi (Lates calcarifer) with a high prevalence of gastrointestinal cryptosporidiosis are described. Juvenile barramundi at a separate hatchery and grow-out facility were demonstrating markedly increased mortality rates. Histological examination in all cases indicated a heavy infection of Cryptosporidium-...

Three direct fluorescent-antibody staining assay kits for the detection of zoonotic Cryptosporidium species were used to detect Cryptosporidium molnari from Murray cod, and the cryptosporidia were characterized by using small-subunit (SSU) ribosomal DNA (rDNA). To facilitate rapid diagnosis of infection, this study demonstrated that all three kits...

Low-grade alimentary lymphoma (LGAL) is a recently described entity displaying many microscopical features similar to lymphoplasmacytic enteritis (LPE). The aim of this study was to review the histopathological and immunohistochemical features of LPE and LGAL to determine if specific features are useful in distinguishing between these disorders. Fi...

There is an increasing need for more accurate prognostic and predictive markers in veterinary oncology because of an increasing number of treatment options, the increased financial costs associated with treatment, and the emotional stress experienced by owners in association with the disease and its treatment. Numerous studies have evaluated potent...

Neoplastic diseases are typically diagnosed by biopsy and histopathological evaluation. The pathology report is key in determining prognosis, therapeutic decisions, and overall case management and therefore requires diagnostic accuracy, completeness, and clarity. Successful management relies on collaboration between clinical veterinarians, oncologi...

Soft tissue sarcomas (STSs) develop from mesenchymal cells of soft tissues, and they commonly occur in the skin and subcutis of the dog. Although phenotypically diverse with frequently controversial histogenesis, STSs are considered as a group because they have similar features microscopically and clinically. Following resection, local recurrence r...

Cardicola forsteri is a blood fluke that is highly prevalent among cultured southern bluefin tuna (SBT), Thunnus maccoyii, in South Australia. The role of C forsteri in annual SBT mortality outbreaks, which peak 6 to 12 weeks poststocking, is unknown. The objective of this study was to identify lesions unique to cultured SBT that died during a mort...

Viruses in three genera of the family Iridoviridae (iridoviruses) affect finfish. Ranaviruses and megalocytiviruses are recently emerged pathogens. Both cause severe systemic disease, occur globally and affect a diversity of hosts. In contrast, lymphocystiviruses cause superficial lesions and rarely cause economic loss. The ranavirus epizootic haem...

To determine the suitability and estimate the sensitivity of an immunohistochemical (IHC) test for disease-associated prion protein (PrP(Sc)) in biopsy specimens of rectoanal mucosa-associated lymphoid tissue (RAMALT) for diagnosis of scrapie in sheep. 762 sheep at high risk for having scrapie and indemnified by the National Scrapie Eradication Pro...

Exocrine pancreatic carcinoma is a particularly malignant neoplasm of the dog. Clinical and pathologic findings of an unusual variant of exocrine pancreatic neoplasia termed hyalinizing pancreatic adenocarcinoma were evaluated in 6 dogs. On microscopic examination, neoplasms were composed of tubules and acini of epithelial cells, with bright eosino...

Disseminated infection (DI) of Mycobacterium avium subspecies paratuberculosis (MAP) in cattle may impair cow health, potentiate spread of disease, and is a potential food-safety risk. The objectives of this study were to determine the association between severity of histologic enteric lesions and the occurrence of DI, clinical signs, and positive...

Mycobacterium avium subspecies paratuberculosis (MAP) disseminated infection in dairy cattle affects animal health and productivity and is also a potential public health concern. The study objectives were to characterize MAP disseminated infection in dairy cattle and to determine the role of antemortem tests in detecting cattle with disseminated in...

To describe the character and frequency of causes of death and associated lesions in long-distance racing sled dogs. Retrospective case series. 23 dogs. Medical records of dogs that died during or soon after competition in the Iditarod Trail sled dog races (1994 through 2006) were examined for fi ndings of gross necropsy and histologic evaluation o...

The protease-resistant infectious prion protein, PrPres, that causes transmissible spongiform encephalopathies, is remarkably resistant to conventional physical and chemical sterilization methods, including heat. It was hypothesized that thermal-dependent PrPres degradation has been underestimated, and the effect of prolonged incubation at 37 degre...

To categorize histologic lesions affecting the tongue, determine the frequency with which they develop, and identify risk factors associated with their development in dogs. Retrospective case series. 1,196 dogs. Diagnostic reports of lingual biopsy specimens from dogs evaluated from January 1995 to October 2004 were reviewed. Neoplasia comprised 54...