Babesiosis caused by a large Babesia species in 7 immunocompromised dogs.

BACKGROUND: A large unnamed Babesia species was detected in a dog with lymphoma. It was unknown if this was an underrecognized pathogen. OBJECTIVE: Report the historical and clinicopathologic findings in 7 dogs with babesiosis caused by a large unnamed Babesia species characterize the 18S ribosomal ribonucleic acid (rRNA) genes. ANIMALS: Seven immunocompromised dogs from which the Babesia was isolated. METHODS: Retrospective case review. Cases were identified by a diagnostic laboratory, the attending clinicians were contacted and the medical records were reviewed. The Babesia sp. 18S rRNA genes were amplified and sequenced. RESULTS: Six of 7 dogs had been splenectomized; the remaining dog was receiving oncolytic drugs. Lethargy, anorexia, fever, and pigmenturia were reported in 6/7, 6/7, 4/7, and 3/7 dogs. Laboratory findings included mild anemia (7/7) and severe thrombocytopenia (6/7). Polymerase chain reaction (PCR) assays used to detect Babesia sensu stricto species were all positive, but specific PCR assays for Babesia canis and Babesia gibsoni were negative in all dogs. The 18S rRNA gene sequences were determined to be identical to a large unnamed Babesia sp. previously isolated. Cross-reactive antibodies against other Babesia spp. were not always detectable. Five dogs were treated with imidocarb dipropionate and 1 dog with atovaquone/azithromycin; some favorable responses were noted. The remaining dog was untreated and remained a clinically stable carrier. CONCLUSIONS AND CLINICAL IMPORTANCE: Dogs with pigmenturia, anemia, and thrombocytopenia should be tested for Babesia sp. by PCR. Serology is not sufficient for diagnosis of this Babesia sp. Asplenia, chemotherapy, or both might represent risk factors for persistent infection, illness, or both.

Evaluation of brain tissue or cerebrospinal fluid with broadly reactive polymerase chain reaction for Ehrlichia, Anaplasma, spotted fever group Rickettsia, Bartonella, and Borrelia species in canine neurological diseases (109 cases).

BACKGROUND: Vector-transmitted microorganisms in the genera Ehrlichia, Anaplasma, Rickettsia, Bartonella, and Borrelia are commonly suspected in dogs with meningoencephalomyelitis (MEM), but the prevalence of these pathogens in brain tissue and cerebrospinal fluid (CSF) of dogs with MEM is unknown. HYPOTHESIS/OBJECTIVES: To determine if DNA from these genera is present in brain tissue and CSF of dogs with MEM, including those with meningoencephalitis of unknown etiology (MUE) and histopathologically confirmed cases of granulomatous (GME) and necrotizing meningoencephalomyelitis (NME). ANIMALS: Hundred and nine dogs examined for neurological signs at 3 university referral hospitals. METHODS: Brain tissue and CSF were collected prospectively from dogs with neurological disease and evaluated by broadly reactive polymerase chain reaction (PCR) for Ehrlichia, Anaplasma, Spotted Fever Group Rickettsia, Bartonella, and Borrelia species. Medical records were evaluated retrospectively to identify MEM and control cases. RESULTS: Seventy-five cases of MUE, GME, or NME, including brain tissue from 31 and CSF from 44 cases, were evaluated. Brain tissue from 4 cases and inflammatory CSF from 30 cases with infectious, neoplastic, compressive, vascular, or malformative disease were evaluated as controls. Pathogen nucleic acids were detected in 1 of 109 cases evaluated. Specifically, Bartonella vinsonii subsp. berkhoffii DNA was amplified from 1/6 dogs with histopathologically confirmed GME. CONCLUSION AND CLINICAL IMPORTANCE: The results of this investigation suggest that microorganisms in the genera Ehrlichia, Anaplasma, Rickettsia, and Borrelia are unlikely to be directly associated with canine MEM in the geographic regions evaluated. The role of Bartonella in the pathogenesis of GME warrants further investigation.

Bartonella DNA in the blood and lymph nodes of Golden Retrievers with lymphoma and in healthy controls.

BACKGROUND: Although lymphoma is the most common neoplastic process reported in dogs, its precise etiology is unknown. Golden Retrievers are more likely to develop lymphoma, suggesting a breed predisposition; however, other factors, including environment, immunity, and infection, are likely contributors to oncogenesis. HYPOTHESIS: We hypothesized that the development of lymphoma in Golden Retrievers may be associated with vector-borne infections, specifically Bartonella, Anaplasma, or Ehrlichia species infections. ANIMALS: Golden Retrievers with lymphoma and healthy Golden Retrievers from across the United States were recruited for study participation. METHODS: A matched, case-control study was performed to determine the association of lymphoma and the presence of Bartonella, Anaplasma, and Ehrlichia species in serum, blood, and lymph node aspirates. RESULTS: Using PCR analyses and DNA sequencing, single and coinfections with Bartonella henselae, Bartonella elizabethae, Bartonella quintana, and/or Bartonella vinsonii (berkhoffii) were detected in the blood and lymph node aspirates of Golden Retrievers with lymphoma (5/28 dogs, 18%) and in healthy Golden Retrievers (10/56 dogs, 18%); no Anaplasma or Ehrlichia DNA was detected in any dog. When compared with dogs with lymphoma, a higher (P <.001) proportion of healthy Golden Retrievers were receiving monthly acaricide treatments (2.6 times higher). CONCLUSIONS AND CLINICAL IMPORTANCE: Bartonella DNA can be detected in blood and lymph nodes; importantly, in this report, Bartonella was detected in the same proportion of clinically healthy dogs and dogs with lymphoma. Longitudinal studies should be conducted to determine the mode of transmission of Bartonella in dogs, whether lymphatic infection is persistent, or whether these bacteria may contribute to the development of lymphoma.

Intermittent At-Home Suctioning of Esophageal Content for Prevention of Recurrent Aspiration Pneumonia in 4 Dogs with Megaesophagus.

BACKGROUND: Megaesophagus carries a poor to guarded prognosis due to death from aspiration pneumonia. Options for medical management of regurgitation are limited to strategic oral or gastrostomy tube feeding. OBJECTIVES: To describe the use and efficacy of intermittent esophageal suctioning to prevent regurgitation and associated episodes of aspiration pneumonia in dogs with megaesophagus. ANIMALS: Four dogs with acquired idiopathic megaesophagus and recurrent aspiration pneumonia. METHODS: Retrospective review of medical records of dogs with megaesophagus in which intermittent suctioning of esophageal content was employed for management of recurrent aspiration pneumonia. RESULTS: Intermittent suctioning of the esophagus was initiated in 4 dogs after failure of strict gastrostomy tube feeding failed to prevent regurgitation and repeated episodes of aspiration pneumonia. Suctioning was accomplished by esophagostomy tube in 3 dogs and per os in 1 dog. After initiation of esophageal suctioning, dogs survived for a median of 13.5 additional months (range, 10-30 months) during which time 2 dogs had no additional episodes of aspiration pneumonia and 2 dogs had infrequent episodes of pneumonia, but aspiration was suspected to be a contributing factor in their death. Complications included clogging of the esophagostomy tube, esophagostomy site infections, and esophagitis. CONCLUSIONS AND CLINICAL IMPORTANCE: Use of intermittent esophageal suctioning in dogs with megaesophagus that continue to regurgitate despite gastrostomy tube feedings can reduce or abolish clinical episodes of aspiration pneumonia.

There are at least three genetically distinct small piroplasms from dogs.

The 18S nuclear subunit ribosomal RNA (18S rRNA) gene of small piroplasms isolated from dogs from Okinawa (Japan), Oklahoma, North Carolina, Indiana, Missouri, and Alabama, was isolated and sequenced. Phylogenetic analysis of these sequences and comparisons with sequences from other Babesia, Cytauxzoon, and Theileria species revealed that all canine small babesial isolates, with the exception of isolates from California and Spain, were placed in a group containing the Babesia spp. sensu stricto. Within the Babesia spp. sensu stricto, there was support for separating the small canine piroplasms from the large canine piroplasm, Babesia canis. The isolate from California was in a distinct phylogenetic clade, closely related to babesial isolates from wildlife and humans from the Western US. The canine isolate from Spain was closely related to Babesia microti. These results suggest that there are multiple small piroplasm species in dogs. The isolates from the Midwestern and Eastern US and the one from Japan probably represent a single species with wide geographic distribution.

Detection and molecular characterization of a novel large Babesia species in a dog.

Babesia canis has generally been considered the only large Babesia to infect dogs. Here we describe the molecular characterization of a large Babesia species that was detected in the blood and bone marrow of a dog with clinical and hematological abnormalities consistent with babesiosis. Analysis of the 18S rRNA genes revealed a unique sequence that shared 93.9% sequence identity with B. bigemina and 93.5% sequence identity with B. caballi, compared to 91.2-91.6% identity with B. canis canis, B. c. vogeli, and B. c. rossi. Cross-reactive antibodies against B. canis, B. gibsoni (Asian genotype), or B. gibsoni (California genotype) antigens were not detected in acute or convalescent serum samples. The dog was treated with imidocarb diproprionate, which resulted in the resolution of clinical signs, and subsequently Babesia DNA was not detectable by PCR in post-treatment samples. The organism described in this report represents a genetically unique large Babesia sp. and is the eighth genetically distinct piroplasm capable of infecting the domestic dog.

Splenosystemic shunts in cats: a retrospective of 33 cases (2004-2011).

BACKGROUND: Portosystemic shunts are uncommonly reported in cats. The majority of reports describe congenital shunts in young cats originating from the left gastric vein. Although they are only rarely reported, acquired portosystemic shunts in cats appear to be more variable in their anatomic location. HYPOTHESIS/OBJECTIVE: To describe the signalment and disease conditions found in cats with splenosystemic shunts. ANIMALS: Thirty-three client-owned cats with documented splenosystemic shunts. MATERIALS AND METHODS: Retrospective study. All cats with vascular communications between the splenic and left renal veins or the splenic vein and caudal vena cava diagnosed ultrasonographically between 2004 and 2011 were included. Collected data included age, breed, sex, presenting complaints, clinicopathologic data, as well as clinical diagnosis when available. RESULTS: Splenosystemic shunts were identified in 1.3% of the cats that had an abdominal ultrasound performed during the study period. Older, spayed female cats were found to be significantly overrepresented when compared with the total population of cats having undergone ultrasound over the same time period. A large proportion of cats (42%) had a hepatopathy with the potential for associated portal hypertension. CONCLUSIONS AND CLINICAL IMPORTANCE: Neither the signalment of cats in this report nor the anatomy of their portovascular anomalies shared similarities with those cats previously identified with single-vessel shunts. The relevance and etiology of these newly described splenosystemic shunts remain elusive and warrantsfurther investigation.

Diminazene diaceturate for treatment of chronic Cytauxzoon felis parasitemia in naturally infected cats.

BACKGROUND: Cytauxzoon felis is a hemoprotozoal parasite that causes substantial morbidity and mortality during the acute phase of infection in cats. However, cats that survive the acute illness remain persistently infected and may serve as a reservoir for the tick-transmitted pathogen. OBJECTIVE: We investigated the ability of the antiprotozoal compound diminazene diaceturate to eliminate the pathogen from naturally infected C. felis carriers. ANIMALS: Seven healthy, chronically infected domestic cats housed in a research setting. METHODS: Prospective clinical trial. Cats were treated in a masked fashion with diminazene diaceturate (3 mg/kg) or placebo IM in a series of 2 injections 7 days apart. Clearance of the organism was assessed by light microscopy and real-time polymerase chain reaction (PCR) at 0, 3, 6, and 10 weeks. In addition, cats were monitored for behavioral changes or for changes on physical examination, CBC, plasma biochemical profile, and urinalysis periodically. Cats that remained parasitemic at the end of 10 weeks were switched to the alternative treatment and similarly monitored for an additional 10 weeks. RESULTS: Adverse events associated with treatment were limited to self-resolving hypersalivation and injection site soreness; the former was ameliorated by premedication with atropine. Parasite burden, as assayed by both light microscopy and real-time PCR, was similar between diminazene- and placebo-treated cats. CONCLUSIONS AND CLINICAL RELEVANCE: Diminazene diaceturate was unable to eliminate the pathogen or decrease parasite burden in healthy, chronically infected cats.

Hypocalcemia and hypovitaminosis D in dogs with induced endotoxemia.

BACKGROUND: Hypocalcemia is a documented electrolyte disturbance in people and animals with sepsis, but its mechanism is poorly understood. OBJECTIVE: To investigate mechanisms of hypocalcemia in dogs with experimentally induced endotoxemia. ANIMALS: Six healthy mixed breed dogs were included in this nonrandomized, placebo-controlled, crossover study. METHODS: Dogs initially were injected with placebo (0.9% NaCl; 1 mL, IV) and then lipopolysaccharide (LPS; 2 µg/kg, IV) after a 5-day washout period. Blood and urine samples were collected for measurement of serum total calcium (tCa), ionized calcium (iCa), total magnesium (tMg), ionized magnesium (iMg), parathyroid hormone (PTH), 25-hydroxyvitamin D (vitamin D), venous blood gases, and fractional excretion (FE) of calcium. RESULTS: After LPS administration, body temperature increased and blood pressure decreased. Both iCa and tCa decreased (P < .01), but iMg was not significantly different between control and LPS treatments. PTH concentrations increased (P < .01) and vitamin D concentrations decreased (P < .01). Venous pH, bicarbonate, base excess, and blood glucose also decreased (P < .01). Urine tCa concentration was below the limit of detection for all dogs after LPS administration. CONCLUSIONS: Hypocalcemia occurs during endotoxemia in dogs and is associated with hypovitaminosis D. Hypomagnesemia, hypoparathyroidism, alkalosis, and increased calciuresis are not associated with hypocalcemia in endotoxemic dogs.

Efficacy of atovaquone and azithromycin or imidocarb dipropionate in cats with acute cytauxzoonosis.

BACKGROUND: Imidocarb or a combination of atovaquone and azithromycin (A&A) has been suggested for treatment of cats with cytauxzoonosis, but neither has been prospectively evaluated for efficacy. HYPOTHESIS/OBJECTIVES: That survival to hospital discharge is improved by treatment with A&A as compared with imidocarb. ANIMALS: Eighty acutely ill cats with Cytauxzoon felis infection treated at one of 18 veterinary clinics in 5 states. METHODS: An open-label, randomized prospective study compared survival in cats treated with atovaquone (15 mg/kg p.o. q8h) and azithromycin (10 mg/kg p.o. q24h) or imidocarb (3.5 mg/kg i.m.). All received heparin, fluids, and supportive care. Clinical and clinicopathologic data from initial presentation were collated. Parasitemia was quantified (n = 79) and pathogens genotyped (n = 60). Logistic regression was used to determine the impact of treatment group on the primary endpoint, survival to hospital discharge or death. Covariants were analyzed by rank-sum testing. RESULTS: Of 53 cats treated with A&A, 32 (60%) survived to discharge while only 7 of 27 cats (26%) treated with imidocarb survived (P = .0036; odds ratio 7.2, 95% CI 2.2, 24). Cats with a lower parasitemia were more likely to survive, as were cats with higher white blood cell counts and lower total bilirubin. Unique pathogen genotypes were identified from 15 cats, while genotype isolated from 21 cats had been described previously. There were multiple pathogen genotypes identified in 24 cats. CONCLUSIONS AND CLINICAL IMPORTANCE: Survival to discharge was more likely in cats treated with A&A as compared with imidocarb, although case fatality rate remained high.

Molecular evidence of prevalent dual piroplasma infections in North American raccoons (Procyon lotor).

Based on 18S rRNA sequence analyses 2 distinct genotypes of piroplasms have been described in raccoons. One genotype resides in the Babesia sensu stricto clade and the other in the Babesia microti-like clade. Since these organisms appear morphologically indistinguishable, it is unclear which strain is responsible for the majority of the infections in raccoons. In order to overcome these limitations we performed a molecular survey of raccoons using polymerase chain reaction assays specific for each genotype. We tested blood samples from 41 wild raccoons trapped in eastern North Carolina using PCR assays and found that 95% (39/41) had detectable piroplasm DNA. Ninety percent (37/41) of the samples contained Babesia sensu stricto DNA and 83% (34/41) samples contained Babesia microti-like DNA. DNA from both genotypes was present in 76% (31/41) samples suggesting a very high rate of co-infections. The presence of dual piroplasma infections in carnivores appears to be an uncommon finding. This study highlights the need for molecular assays for the accurate identification of piroplasma. Further studies are indicated to investigate the ability of these parasites to infect domestic animals as well as their zoonotic potential.

The identification of a genetically unique piroplasma in North American river otters (Lontra canadensis).

During a routine health check of a wild-caught North American river otter (Lontra canadensis) small piroplasms were noted within erythrocytes. Analyses of the 18S ribosomal ribonucleic acid (rRNA) gene sequences determined that this was a genetically unique organism most closely related to Babesia microti-like parasites found in other small carnivores. Subsequently 39 wild-trapped North American river otters from North Carolina were tested for the presence of piroplasma deoxyribonucleic acid (DNA) via polymerase chain reaction and piroplasma DNA was detected in 82% (32/39) of these samples. Sequencing of partial 18S rRNA genes from selected cases determined that they were identical to the sentinel case. This report documents the existence of a genetically unique piroplasma in North American river otters and indicates that the prevalence of piroplasma in North Carolina otters is quite high. The pathogenic potential of this organism for otters or other species remains unknown.

Canine Rocky Mountain Spotted fever: a retrospective study of 30 cases.

Rocky Mountain spotted fever (RMSF) was diagnosed in 30 dogs examined at North Carolina State University, Veterinary Teaching Hospital between 1984 and 1997. Historical, physical examination, and laboratory abnormalities were reviewed. Diagnostic criteria included a four-fold rise in antibody titer to Rickettsia rickettsii (R. rickettsii) (n=15) or a single R. rickettsii antibody titer of 1:1,024 or greater (n=15; when this initial titer was determined one week or more after the onset of clinical signs). Fifteen (50%) dogs were greater than seven years of age, and 13 (43%) dogs were between two and seven years of age. There was no sex predilection. Only five (17%) dogs had a history of known tick exposure. Presumably due to delayed diagnosis, dogs with antibody titers of 1:1,024 or greater at the time of presentation had a higher incidence of more severe neurological dysfunction (e.g., ataxia, hyperesthesia, vestibular disease, and seizures) and cutaneous lesions (e.g., hyperemia, edema, petechiae, ecchymoses, and necrosis). Laboratory findings included anemia, leukocytosis accompanied by toxic granulation of neutrophils, hypoalbuminemia, and coagulation abnormalities; signs were generally more severe in the 15 dogs with R. rickettsii antibody titers of 1:1,024 or greater at the time of presentation. Twelve (40%) dogs in this study were severely thrombocytopenic (less than 75 x10(3) platelets/microl; reference range, 200 to 450 x 10(3)/microl), without clinical evidence of fulminant disseminated intravascular coagulation. In this study, the survival rate following R. rickettsii infection was 100%.

Babesia gibsoni infections in dogs from North Carolina.

The recognition of canine babesiosis in North Carolina caused by Babesia gibsoni documents the expansion of the previously reported endemic area of this disease. Clinical signs ranged from severe hemolytic anemia and thrombocytopenia to subclinical infections. No infected dogs had traveled to endemic areas. Antibabesial treatment failed to eradicate the organism from infected dogs.