World Small Animal Veterinary Association Renal Pathology Initiative: Classification of Glomerular Diseases in Dogs.

Evaluation of canine renal biopsy tissue has generally relied on light microscopic (LM) evaluation of hematoxylin and eosin-stained sections ranging in thickness from 3 to 5 µm. Advanced modalities, such as transmission electron microscopy (TEM) and immunofluorescence (IF), have been used sporadically or retrospectively. Diagnostic algorithms of glomerular diseases have been extrapolated from the World Health Organization classification scheme for human glomerular disease. With the recent establishment of 2 veterinary nephropathology services that evaluate 3-µm sections with a panel of histochemical stains and routinely perform TEM and IF, a standardized objective species-specific approach for the diagnosis of canine glomerular disease was needed. Eight veterinary pathologists evaluated 114 parameters (lesions) in renal biopsy specimens from 89 dogs. Hierarchical cluster analysis of the data revealed 2 large categories of glomerular disease based on the presence or absence of immune complex deposition: The immune complex-mediated glomerulonephritis (ICGN) category included cases with histologic lesions of membranoproliferative or membranous patterns. The second category included control dogs and dogs with non-ICGN (glomerular amyloidosis or focal segmental glomerulosclerosis). Cluster analysis performed on only the LM parameters led to misdiagnosis of 22 of the 89 cases-that is, ICGN cases moved to the non-ICGN branch of the dendrogram or vice versa, thereby emphasizing the importance of advanced diagnostic modalities in the evaluation of canine glomerular disease. Salient LM, TEM, and IF features for each pattern of disease were identified, and a preliminary investigation of related clinicopathologic data was performed.

Depolarization of rat basophilic leukemia cells inhibits calcium uptake and exocytosis.

We have investigated the unusual observation that depolarization of rat basophilic leukemia cells in high potassium not only fails to induce secretion, but also inhibits the secretion induced when receptors for IgE are aggregated by antigen. Antigen-stimulated 45Ca uptake and the rise in cytoplasmic free ionized calcium measured with the fluorescent indicator quin2 were both inhibited in depolarized cells. 45Ca efflux, on the other hand, was unaffected, which confirms that IgE receptor activation was not impaired in high potassium. Unlike the large increase in total cell calcium seen when cells in normal saline solution were stimulated with antigen, there was a decrease in total cell calcium when depolarized cells were stimulated. This is consistent with our finding that 45Ca uptake was inhibited while 45Ca efflux was unaffected. Inhibition of 45Ca uptake and secretion closely paralleled the decrease in membrane potential, and could be overcome by increasing the extracellular calcium concentration. We conclude that changes in the electrochemical gradient for calcium are important in determining calcium influx and the magnitude of antigen-stimulated secretion from rat basophilic leukemia cells, while the release of calcium from intracellular stores is unaffected.

Clinicopathologic and Histopathologic Renal Abnormalities in Dogs with Coccidioidomycosis.

BACKGROUND: We observed evidence of protein-losing nephropathy in some dogs with coccidioidomycosis, suggestive of immune complex glomerulonephritis (ICGN). The goal of this study was to understand the prevalence of renal histopathologic lesions and proteinuria in dogs with coccidioidomycosis. HYPOTHESIS: Biochemical and histopathological evidence of glomerular lesions is present in dogs with coccidioidomycosis. ANIMALS: Hundred and fifty-six dogs with naturally occurring coccidioidomycosis. METHODS: Retrospective case series. Clinical information and results of clinicopathologic testing were retrieved from the University of California, Davis Veterinary Medical Teaching Hospital (VMTH). Microscopic sections of renal tissue procured from necropsy of dogs with coccidioidomycosis were examined to evaluate the nature and distribution of lesions. RESULTS: A total of 156 dogs with coccidioidomycosis were identified; 87 dogs had serum biochemistry and a urinalysis performed, 17 had urine protein:creatinine ratios (UPCs), and 24 had renal tissue available for histopathology. Eleven (13%) of the 87 dogs were azotemic, 55 (63%) were proteinuric (of which 14 [25%] had clinically relevant proteinuria defined as ≥3+ or ≥500 mg/dL), and 14 dogs had UPC ≥0.5 (range, 0.5-21.5, median 4.2). Thirteen (54%) of 24 dogs had renal histopathologic lesions suggestive of ICGN. Seven of these dogs had urinalyses performed; 5 (71%) had clinically relevant proteinuria as described above. Two dogs (33%) with normal glomeruli had granulomatous nephritis, 1 of which had intralesional Coccidioides spherules. CONCLUSIONS AND CLINICAL IMPORTANCE: Coccidioidomycosis should be considered as a possible contributor to glomerular disease in dogs. Whether similar lesions occur in other mammalian hosts, including humans, warrants further investigation.

Regulation of inositol 1,4,5-trisphosphate receptors in rat basophilic leukemia cells. I. Multiple conformational states of the receptor in a microsomal preparation.

A detailed characterization of the inositol 1,4,5-trisphosphate (IP3) receptor in rat basophilic leukemia (RBL) cells, a neoplastic mast cell line, has been possible through the growth of solid RBL cell tumors which provide a rich source of IP3 receptor. Equilibrium binding studies show a 1.6 +/- 0.1 pmol/mg of protein maximal binding capacity for [3H]IP3 at optimal Ca2+ (10 microM). The specificity of the RBL cell IP3 receptor towards phosphoinositides, ATP and heparin parallels those previously described with excitable and nonexcitable tissues. [3H]IP3 binding is slightly enhanced from < 1 nM to 10 microM Ca2+ and inhibited by > 10 microM Ca2+. Kinetic and equilibrium studies provide evidence for at least two classes or conformational states of binding sites with pico- and nanomolar affinities. At nM concentrations of IP3, neither binding to the IP3 receptor nor IP3-induced Ca2+ efflux from permeabilized cells demonstrates cooperativity. In contrast, at pM concentrations, IP3 binding kinetics deviate from simple mass action suggesting a complex interaction among binding sites for IP3 on the receptor-channel oligomer. The mechanisms that regulate [3H]IP3 binding in RBL cells are unique when compared to what has been reported in other cells.

Regulation of inositol 1,4,5-trisphosphate receptors in rat basophilic leukemia cells. II. Modulation of the receptor in permeabilized cells by the cytosolic compartment.

Engagement of the IP3 receptor by its ligand releases Ca2+ from intracellular stores of the rat basophilic leukemia (RBL) cell. The IP3 receptor in washed permeabilized cells has high affinity (Kd = 1.2 +/- 0.3 nM) for [3H]IP3 and is not sensitive to physiological concentrations of Ca2+. Moreover, washed permeabilized cells only release small amounts of Ca2+ when stimulated with IP3. When [3H]IP3 binding to permeabilized cells is performed in the presence of cytosolic constituents (unwashed cells), the IP3 receptor has a lower affinity for [3H]IP3 (Kd from 20 to 100 nM) and has enhanced Ca2+ release. Cytosolic supernatant, prepared by centrifugation of permeabilized cells and added back to washed permeabilized cells, decreases [3H]IP3 binding in a dose-dependent manner and increases the amount of Ca2+ released by IP3. Depletion of either MgATP or IP3 in the cytosolic supernatant does not affect the supernatant's ability to decrease [3H]IP3 binding. Though MgATP competitively inhibits [3H]IP3 binding, it cannot fully account for the shift in Kd or the modulation of IP3-stimulated Ca2+ release in the presence of cytosol. These findings suggest that components present in the cytosolic supernatant modulate the function of the IP3 receptor by maintaining it in a low affinity state capable of promoting Ca2+ release.

Failure of Herpesvirus saimiri to enhance atherogenesis in owl monkeys (Aotus trivirgatus).

A retrospective study was performed to evaluate the potential of a mammalian oncogenic virus, Herpesvirus saimiri, to cause atherosclerosis in owl monkeys (Aotus trivirgatus). This was undertaken since an avian oncogenic herpesvirus, Marek's disease virus, does so in chickens. Data from earlier studies were reviewed and 3 groups of animals were selected. These included 23 animals infected with herpesvirus that died an average of 156 days later with malignant lymphoma; 11 infected an average of 207 days before being killed without lymphoma; and 21 uninfected control animals that died from a variety of diseases. Aortas and hearts from all animals were recovered from storage in formalin and examined for histopathological evidence of atherosclerosis in aortas and coronary arteries. Mild to moderate atherosclerosis characterized by intimal proliferation and the presence of fat droplets was present in 60% of the monkeys and did not differ in occurrence between the groups. Mean intimal thickness did not vary significantly between groups either. A case of naturally-occurring severe atherosclerosis is also reported here. Thus, although this species is susceptible to atherosclerosis, neither the occurrence nor severity of that disease is affected by infection with an oncogenic virus within the time periods studied here.

Relationships between maternal and fetal liver copper, iron, manganese, and zinc concentrations and fetal development in California Holstein dairy cows.

Associations between maternal trace element deficiencies and abortion have been made for many mammalian species. Objectives of this study were to estimate and correlate maternal and fetal hepatic Cu, Fe, Mn, and Zn concentrations through gestation. Additionally, aborted fetuses, stratified by cause of abortion (infectious or noninfectious), were compared to size-matched nonaborted fetuses to examine for magnitude and direction of change in hepatic trace element status. Dam and fetal liver were removed at slaughter from 103 Holstein dairy cows judged grossly normal by ante- and postmortem examination. Liver samples were collected from fetuses submitted by veterinarians for routine diagnosis of abortion (n = 80). Hepatic Cu, Fe, Mn, and Zn concentrations were determined by flame spectrophotometry. Comparisons of groups, estimations of correlations, and derived prediction equations were made by least-squares methods. Maternal liver Cu, Fe, Mn, and Zn concentrations did not vary during gestation. Compared with the dam, fetal liver Fe and Zn concentrations were higher (P < 0.05), fetal Cu concentrations were similar (P > 0.05), and fetal liver Mn concentrations were lower (P < 0.05). As fetal size increased, fetal liver Cu and Zn concentrations increased (P < 0.05), fetal liver Fe concentration decreased (P < 0.05), and fetal liver Mn did not change (P > 0.05). Aborted fetuses had lower liver Cu, Mn, and Zn concentrations than did nonaborted fetuses (P < 0.05). Liver Fe concentration was lower in aborted fetuses than in nonaborted fetuses in the second trimester only (P < 0.05). Consistently lower liver Cu, Fe, Mn, and Zn concentrations in aborted fetuses suggest a nonspecific change in trace element status, which implies an effect of abortion, not a cause of abortion.

Primary diffuse tracheobronchial amyloidosis in a dog.

Primary diffuse tracheobronchial amyloidosis was diagnosed at necropsy in an intact male Akita dog aged 11 years, a non-productive chronic cough having been the only related clinical sign. Histologically, eosinophilic hyalinized deposits were found as a band in the lamina propria underneath the epithelium of the trachea and bronchi. When stained with Congo red, apple-green birefringence was observed in the deposits viewed with polarized light. The amyloid did not lose sensitivity to Congo red staining after incubation with potassium permanganate, indicating that it was of the AL (amyloid light chain) type. Ultrastructural features of the amyloid included a typical fibrillar meshwork with individual fibrils measuring 9.5 to 10.5 nm in diameter. This is the first report of primary diffuse tracheobronchial amyloidosis in the dog.

Culture and initial characterization of the secretory response of neoplastic cat mast cells.

Mast cells isolated from feline splenic mastocytomas were cultured to study their structural and functional properties. Isolated cells from various cats were grown as monolayer cultures for a mean of 56 days (range, 30 to 76 days). Cat mast cells released allergic mediators in response to compound 48/80, anti-cat serum antibodies, and concanavalin A. On the basis of the finding that secretion from cat mast cells was stimulated by anti-cat serum antibodies and concanavalin A, these cells contain surface-bound immunoglobulins. The presence of mast cell-sensitizing antibodies has been suspected in cats, but never before directly demonstrated. Cultured cat mast cells have cytochemical and functional characteristics common to connective tissue-type mast cells and provide one of the few non-rodent models of cultured cells for the study of this type of mast cell.

Herpesvirus particles associated with oral and respiratory lesions in a California desert tortoise (Gopherus agassizii).

A 60-year-old captive California desert tortoise (Gopherus agassizii) which died in August 1990 at the University of California, Davis, California (USA), during treatment for colonic impaction had marked caseous necrosis of the oral cavity, choana, trachea, and lungs. Numerous intranuclear inclusion bodies and a large number of syncytial giant cells were seen in the oral cavity and respiratory tract along with bacterial granulomas. Pasteurella testudinis, Streptococcus veridans, and coagulase-negative Staphilococcus spp. were cultured from the lesions. Using electron microscopy, herpesvirus particles were observed in intranuclear inclusions and cytoplasm. Viral stomatitis, tracheitis, and bronchopneumonia complicated by bacterial infection were diagnosed. Although respiratory disease is common in desert tortoises, this is believed to be the first report of association with a viral infection.

Primary hyperparathyroidism caused by a functional parathyroid adenoma in a horse.

A 14-year-old Arabian gelding had weight loss and anorexia of 3 weeks' duration. Results of repeated laboratory tests revealed persistent hypercalcemia and serum phosphorus concentration that was within or less than the reference range. Parathyroid hormone concentration was high. Histologic examination of specimens obtained at necropsy revealed parathyroid adenoma. A diagnosis of primary hyperparathyroidism attributable to a functional parathyroid adenoma was made. Abnormalities in calcium and phosphorus concentrations were similar to those seen with primary hyperparathyroidism in dogs, in which this syndrome is best described. Primary hyperparathyroidism should be considered to be a potential cause of hypercalcemia in horses in which other more common causes of hypercalcemia, such as humoral hypercalcemia of malignancy, nutritional secondary hyperparathyroidism, chronic renal failure, vitamin D toxicosis, and bony or granulomatous disease, are ruled out.

Odontogenic keratocyst in a cat.

Odontogenic cysts are derived from odontogenic epithelium, can be locally invasive and destructive and have been reported rarely in cats. A 16-year-old, male domestic shorthair cat had a 3-year history of a slowly progressive, right mandibular swelling. Intraoral dental radiographs revealed a multilocular, radiolucent, cystic mass within the right mandible that extended from the distal aspect of the canine tooth to the mesial aspect of the fourth premolar tooth. Radiographically, the mass was associated with distortion and regional destruction of the right mandibular bone and resorption of regional tooth roots. Histological examination of an incisional biopsy sample revealed multiple ruptured cysts lined by stratified squamous epithelium of odontogenic origin with luminal parakeratinization and a prominent palisading basal cell layer. The cyst contained abundant orthokeratotic and parakeratotic keratin. The clinical, radiographical and histological features were consistent with a diagnosis of odontogenic keratocyst, as seen in man. This is the first report of an odontogenic keratocyst in a cat.

Neuroendocrine tumour at the carina of a dog.

A 10-year-old, neutered female, crossbred pit bull terrier was presented for cough, haemoptysis and rapidly progressive respiratory difficulty. Thoracic radiographs suggested a soft tissue density at the carina and bronchoscopy revealed a large, broad-based mass obstructing the entire left mainstem bronchus and half of the entrance to the right mainstem bronchus. Microscopically, the mass consisted of neoplastic cells that were packeted into small nests and had strong granular cytoplasmic immunoreactivity to synaptophysin and chromogranin A. Cytoplasmic neurosecretory granules stained strongly by the Grimelius method. A diagnosis of obstructive neuroendocrine tumour was made.

Clear cell ependymoma in a dog.

A 13-year-old, mixed breed dog presented with a 1-month history of seizures. Magnetic resonance imaging of the brain revealed a 2.2 × 1.0 × 0.9 cm ovoid and elongate cystic mass within the white matter of the left frontal lobe extending caudally from the cribriform plate to the rostral left lateral ventricle. Three fractions of stereotactic radiotherapy were administered and resulted in reduction of the volume of the tumour; however, the clinical signs failed to improve. On post-mortem examination, a single mass 1.5 × 0.3 × 1 cm was found within the left frontal lobe. It consisted of gelatinous, grey, friable tissue bordering a central empty cavity. Microscopical evaluation revealed polygonal neoplastic cells with distinct cytoplasmic borders and one or more intracytoplasmic solid, brightly eosinophilic, sharply defined globules. Immunohistochemically, the neoplastic cells expressed glial fibrillary acidic protein and S100 but were negative for pan cytokeratin, vimentin, olig-2 and synaptophysin. Ultrastructurally, neoplastic cells had dense whorls of intracytoplasmic intermediate filaments and were connected by multiple intermittent long zonula adherens-type junctions. Based on these findings, a diagnosis of clear cell ependymoma was made. This is the first report of this subtype in the dog.

Pathologic evaluation of canine renal biopsies: methods for identifying features that differentiate immune-mediated glomerulonephritides from other categories of glomerular diseases.

BACKGROUND: Human renal biopsies are routinely evaluated with light microscopy (LM) using a panel of histologic stains, transmission electron microscopy (TEM), and immunofluorescence (IF) microscopy to obtain a diagnosis. In contrast, the pathologic evaluation of glomerular disease in veterinary medicine has relied mostly on LM and was of limited utility. To address this problem, recently established veterinary renal diagnostic centers have adopted methods used in human nephropathology for evaluation of renal biopsies. Three broad categories of disease, which have the greatest implications for clinical management of proteinuric dogs, have been established and include amyloidosis, immune complex-mediated glomerulonephritis (ICGN), and non-ICGN. OBJECTIVE: To demonstrate histopathologic, ultrastructural, and IF findings in renal biopsy specimens that experienced veterinary nephropathologists utilize to make accurate and clinically useful diagnoses in dogs with proteinuric glomerular disease and to provide guidelines for the proper evaluation of renal biopsies. METHODS: Renal biopsy specimens were routinely examined by LM, IF, and TEM. Samples were reviewed by members of the World Small Animal Veterinary Association Renal Standardization Study Group to identify lesions that were diagnostic for, or suggestive of, the presence of immune complexes (IC) or amyloidosis in all modalities. Ten guidelines for renal biopsy evaluation were formulated. RESULTS: Each method of investigation contributed important findings that were integrated to make an accurate final morphological diagnosis. The guidelines were validated by an independent group of veterinary pathologists. CONCLUSIONS AND CLINICAL IMPORTANCE: Routine evaluation of renal biopsies with LM, TEM, and IF is feasible and necessary for making accurate, morphologic diagnoses that can be used to guide clinical management of dogs with glomerular disease.

Fuel oil-induced adrenal hypertrophy in ranch mink (Mustela vison): effects of sex, fuel oil weathering, and response to adrenocorticotropic hormone.

Environmental contamination by petroleum hydrocarbons from anthropogenic sources can be a cause of stress for free-ranging wildlife. The response of wildlife to chemical contaminants requires that the hypothalamic-pituitary-adrenal (HPA) axis be precisely regulated to allow for proper glucocorticoid-mediated adaptive responses. Chronic oral exposure to low concentrations of bunker C fuel oil causes the development of adrenal hypertrophy in male ranch mink (Mustela vison) without increasing serum or fecal glucocorticoid concentrations. This hypertrophy is an adaptive response to fuel oil-induced adrenal insufficiency. To determine if the same phenomenon occurs in female mink or male mink exposed to artificially weathered fuel oil, female mink were fed 0 ppm (mineral oil) or 420 ppm fuel oil and male mink were exposed to 0 ppm, 420 ppm fuel oil, or 480 ppm artificially weathered fuel oil in the diet for 60-62 days. At the end of the exposure, serum glucocorticoid concentrations were assayed along with body and organ weight measurements. Fecal glucocorticoid concentrations were assayed at time points throughout the exposure. Male mink fed fuel oil or weathered fuel oil and female mink fed fuel oil had adrenal enlargement without any significant increases in the serum or fecal concentration of glucocorticoids, which is consistent with fuel oil-induced adrenal insufficiency. To address the physiological consequences of adrenal insufficiency, fuel oil-exposed male mink were administered an adrenocorticotropic hormone (ACTH) stimulation test. Fuel oil-exposed animals had a smaller incremental increase in serum glucocorticoid concentration after ACTH challenge compared to control animals. Our findings provide further evidence that the HPA axis of fuel oil-exposed animals is compromised and, therefore, not able to respond appropriately to the diverse stressors found in the environment.

Chronic oral exposure to bunker C fuel oil causes adrenal insufficiency in ranch mink (Mustela vison).

Animals living in the near-shore marine environment are predisposed to contact with chemical contaminants through land- and ocean-based activities. The release of petroleum hydrocarbons into the marine environment is a stressor to this environment and its resident wildlife. The stress response to chemical threats is dependent on an intact hypothalamic-pituitary-adrenal axis, which also may be a target to the effects of these chemicals. Ranch mink (Mustela vison) were used as surrogates for sea otters (Enhydra lutris) to examine the development of adrenal hypertrophy after chronic, oral exposure to low concentrations of bunker C fuel oil. Animals were fed three different concentrations of fuel oil (48, 520, and 908 ppm) or mineral oil (control) for 60-62 days. At the end of the exposure, blood and fecal samples were collected and organs were weighed and examined microscopically. In all fuel oil groups, exposure resulted in adrenal hypertrophy, an adaptation suggestive of adrenal activation. However, concentrations of serum and fecal glucocorticoids and serum progesterone were not elevated over control values. Hematologic parameters and serum chemistries showed no changes consistent with increased adrenal activity. In addition, adrenal glands from animals fed the higher concentrations of fuel oil contained large numbers of heavily vacuolated cells. We conclude that petroleum hydrocarbons are inducing an adrenal insufficiency that leads to the adaptive enlargement of the gland. This would increase the susceptibility of fuel oil-exposed animals to the deleterious effects of other environmental stressors.

Assessment of effects in mink caused by consumption of carp collected from the Saginaw River, Michigan, USA.

Polychlorinated hydrocarbons, including polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs), and polychlorinated dibenzofurans (PCDFs), are ubiquitous environmental contaminants that bioconcentrate in the food chain. Numerous studies have demonstrated mink (Mustela vison) to be one of the most sensitive species to this group of compounds. In recent studies, a lesion characterized by osteoinvasion of epithelial cells into the mandible and maxilla of young mink fed diets containing 3,3',4,4',5-pentachlorobiphenyl (PCB 126) and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) was observed. The objective of the present study was to determine if proliferation of maxillary and mandibular squamous epithelia could be induced in ranch mink exposed to environmentally-derived polychlorinated hydrocarbons (PCBs, PCDDs, and PCDFs) in utero, during lactation, and throughout the growth period. Adult female mink were fed diets containing 0, 10, 20, or 30% carp (Cyprinus carpio) collected from the Saginaw River, Bay City, Michigan, USA, that provided 0.03, 0.83, 1.1, and 1.7 mg total PCBs (tPCBs)/kg feed and 2.5, 28, 47, and 73 ng TCDD toxic equivalents (TEQs)/kg feed, respectively, three weeks prior to breeding through weaning of the resulting offspring. Mink kits were maintained on their respective diets for up to 27 weeks of age. At 6 and 27 weeks of age, six to eight mink in each treatment group were necropsied and their jaws examined for evidence of maxillary and mandibular squamous epithelial proliferation. Results indicated that inclusion of up to 30% carp in the diet (1.7 mg tPCBs/kg feed, 73 ng TEQs/kg feed) had no effect on mink reproduction and kit survivability. However, maxillary and mandibular squamous epithelial proliferation was evident in four of the seven 27-week-old juveniles in the 20% carp group (1.1 mg tPCBs/kg feed, 47 ng TEQs/kg feed) and six of the eight juveniles in the 30% carp group (1.7 mg tPCBs/kg feed group, 73 ng TEQs/kg feed). Hepatic concentrations of tPCBs and TEQs increased in both the 6-week-old kits and the 27-week-old juveniles as the percentage of dietary carp increased. The livers of 6-week-old kits were also assessed for the presence of polybrominated diphenyl ethers, which increased as the percentage of Saginaw River carp in the diet increased.

Pathology of bartonella endocarditis in six dogs.

In a 5-year retrospective study of dogs presenting to the Veterinary Medical Teaching Hospital at the University of California, Davis, there were 31 histologic diagnoses of valvular endocarditis. By polymerase chain reaction (PCR) amplification of embedded valvular tissue, Bartonella organisms were exclusively associated with 6 out of 31 cases (19%). Confirmed Bartonella cases involved the aortic valve alone (five out of six) or in combination with the mitral valve (one of six). Microscopic features of Bartonella endocarditis were compared with valves from non-Bartonella endocarditis and with valvular change unrelated to infectious agents (endocardiosis). Features of Bartonella endocarditis included a combination of fibrosis, mineralization, endothelial proliferation, and neovascularization with variable inflammation. None of these features is specific; however, the combination is distinct both from endocarditis caused by culturable bacteria and from endocardiosis. Ultrastructural analyses revealed both extracellular and intraendothelial bacteria. Clinical history, serology, and PCR are currently necessary to establish an etiologic diagnosis of Bartonella endocarditis.