18 F-FDG-PET/CT as adjunctive diagnostic modalities in canine fever of unknown origin.

Fever of unknown origin (FUO) is a persistent or recurrent fever for which the underlying source has not been identified despite diagnostic investigation. In people, 18 F-fluoro-2-deoxyglucose positron emission tomography (18 F-FDG-PET) alone or in combination with computed tomography (CT) is often beneficial in detecting the source of fever when other diagnostics have failed. Veterinary reports describing use of these modalities in animals with fever of unknown origin are currently lacking. Aims of this retrospective case series were to describe 18 F-FDG-PET or 18 F-FDG-PET/CT findings in a group of dogs with fever of unknown origin. Dogs presenting to a single center between April 2012 and August 2015 were included. A total of four dogs met inclusion criteria and underwent either positron emission tomography (n = 2) or positron emission tomography/CT (n = 2) as a part of their diagnostic investigation. All subjects underwent extensive diagnostic testing prior to 18 F-FDG-PET/CT. Initial diagnostic evaluation failed to identify either a cause of fever or an anatomic location of disease in these four dogs. In each dog, positron emission tomography or positron emission tomography/CT was either able to localize or rule out the presence of focal lesion thereby allowing for directed sampling and/or informed disease treatment. Follow up 18 F-FDG-PET/CT scans performed in two patients showed improvement of observed abnormalities (n = 1) or detected recurrence of disease allowing for repeated treatment before clinical signs recurred (n = 1). Fever resolved after specific treatment in each dog. Findings from the current study supported the use of positron emission tomography or positron emission tomography/CT as adjunctive imaging modalities for diagnosis and gauging response to therapy in dogs with fever of unknown origin.

Retropharyngeal abscess with carotid involvement presenting as fever of undetermined origin in a dog.

A young dog was presented with lethargy and pyrexia of 2 days duration, not responding to empirical treatment. Thorough diagnostic investigation failed to determine the cause. A retropharyngeal abscess became apparent when it eroded into the carotid artery 2 days later. This case highlights the challenging nature of fever of undetermined origin (FUO) and the value of close monitoring for diagnosis and prompt intervention.

Abcès rétro-pharyngien avec une atteinte de la carotide et une fièvre d'origine indéterminée chez un chien. Un jeune chien a été présenté pour un abattement et une pyrexie d'une durée de 2 jours et il ne répondait pas au traitement empirique. Une enquête diagnostique complète n'a pas réussi à déterminer la cause. Un abcès rétro-pharyngien est devenu apparent lorsqu'il s'est érodé dans la carotide 2 jours plus tard. Ce cas souligne la nature difficile d'une fièvre d'origine indéterminée et la valeur d'une étroite surveillance pour le diagnostic et une intervention rapide.(Traduit par Isabelle Vallières).

Comparative microbiological features of Bartonella henselae infection in a dog with fever of unknown origin and granulomatous lymphadenitis.

We report the first documented case of Bartonella henselae infection in a dog from France and the first isolation of B. henselae from a dog with fever of unknown origin. This observation contributes to the "One Health" concept focusing on zoonotic pathogens emerging from companion animals. A 1-year-old female German shepherd dog was referred for evaluation of fever of unknown origin of 1 month duration. Diagnostic investigations confirmed diffuse pyogranulomatous lymphadenitis. The dog became afebrile, and lymph node size normalized in response to a 6-week course of doxycycline. Retrospectively, Bartonella DNA was amplified from an EDTA-anticoagulated blood sample obtained before antimicrobial therapy, with the gtlA fragment sharing 99 % identity with the 350-bp gtlA fragment of the B. henselae Houston-1 strain. The same strain was isolated in the blood of three healthy cats from the household. Two months after discontinuation of doxycycline, the dog experienced a febrile relapse. Bartonella DNA was again amplified from blood prior to and immediately after administration of a 6-week course azithromycin therapy. However, without administration of additional medications, PCR was negative 9 months after azithromycin therapy and the dog remains clinically healthy 12 months following the second course of antibiotics. The medical management of this case raises several clinically relevant comparative infectious disease issues, including the extent to which Bartonella spp. contribute to fever of unknown origin and pyogranulomatous inflammatory diseases in dogs and humans, and the potential of doxycycline and azithromycin treatment failures. The possibility that dogs could constitute an underestimated reservoir for B. henselae transmission to people is also discussed.

Diagnostic exercise: poor performance in a racehorse.

A 9-year-old Thoroughbred gelding presented with a 97-day history of poor performance and intermittent fever. Clinicopathologic changes included increased serum activity of γ-glutamyltransferase and alkaline phosphatase, mild hyperbilirubinemia, and leukocytosis with neutrophilia and lymphopenia. Abdominal ultrasound revealed hepatomegaly with hyperechoic hepatic parenchyma and biliary distention. Pathologic findings included marked hepatomegaly (liver 3.6% of body weight), firm hepatic consistency with a diffuse enhanced reticular pattern, severe portal bridging and sinusoidal fibrosis, oval cell/bile duct hyperplasia, and bile stasis. The differential diagnoses and diagnostic workup to achieve the diagnosis are briefly discussed.

Causes, diagnostic signs, and the utility of investigations of fever in dogs: 50 cases.

This study aimed to determine the distribution of diseases causing fever in dogs in France. Dogs with fever were reviewed and 50 dogs were retrospectively assigned to disease groups. Fever profile and intensity, the time taken to reach a diagnosis, and inflammatory status were compared among groups. Almost half the dogs (48%) were diagnosed with non-infectious inflammatory diseases. No final diagnosis was reached in 14 dogs, 13 of which belonged to owners who did not wish to pursue the investigations. No association was found between disease group and the intensity of fever, fever profile, or serum C-reactive protein concentration. Cytological examinations were most frequently found to be the most important determinant for diagnosis (55.7%). This study confirms the predominance of non-infectious inflammatory diseases as causes of fever. Neither clinical nor biological factors were found to be predictive of disease group.

The diagnostic approach to fever of unknown origin in dogs.

Identifying the cause of a fever of unknown origin (FUO) in dogs presents a considerable diagnostic challenge. The diagnostic workup can be frustrating for veterinarians and clients, especially when it fails to reach a final diagnosis after extensive testing. Fortunately, most causes of FUO can be found or treated successfully. This article discusses FUO in dogs and provides information about common causes, the diagnostic approach, and potential treatments.

The diagnostic approach to fever of unknown origin in cats.

Fever is a common clinical sign in cats, but its cause is not always apparent. This article presents a thorough overview of physical examination findings and diagnostic tests that can help guide diagnosis of the underlying condition.

Intestinal neoplasia in horses.

BACKGROUND: Intestinal neoplasia of horses is inadequately described. HYPOTHESIS: Intestinal neoplasia of horses has characteristic clinicopathologic features. ANIMALS: Thirty-four horses with intestinal neoplasia. METHODS: Retrospective study. RESULTS: Anamnesis, clinical signs, clinicopathologic and pathologic findings in 34 adult horses diagnosed histologically with intestinal neoplasia were reviewed. The horses ranged in age from 2 to 30 years (mean 16.6 years at presentation). The Arabian breed was most represented and there was no sex predisposition. The most common presenting complaints were weight loss, colic, anorexia, and fever. The most consistent clinical signs were poor body condition, tachycardia, tachypnea, fever, and diarrhea. Useful diagnostic tools included rectal examination, routine blood analyses, abdominocentesis, ultrasonographic examination, rectal biopsy, and exploratory laparotomy. Alimentary lymphoma was the most common intestinal neoplasia identified, followed by adenocarcinoma and smooth muscle tumors. The small intestine was the most common segment of intestine affected for all neoplasms. Intestinal neoplasia was diagnosed antemortem in 13 of 34 (38%) horses. The median time from onset of clinical signs to death or euthanasia was 1.9 months. The discharge rate was 15%. Although the longest survival was observed in horses with jejunal adenocarcinoma, all horses were eventually euthanized because of intestinal neoplasia. CONCLUSIONS: Arabian horses were 4.5 times more likely to have intestinal neoplasia diagnosed than were other breeds.

Retrospective study of fever in dogs: laboratory testing, diagnoses and influence of prior treatment.

OBJECTIVES: To analyse the demographic information of dogs referred for investigation of fever, to determine the usefulness of various diagnostic investigations and to assess the effect of treatment before referral on the presence of fever at referral, the duration of the investigation and the ability to reach a final diagnosis. METHODS: The clinical records of 66 dogs, in which fever was part of the clinical signs documented by the referring veterinary surgeon, were reviewed. The effects of treatment 24 hours before referral on temperature at initial consultation and on time to diagnosis were evaluated. The effect of body temperature at initial consultation on cost and on time to diagnosis was also determined. The effect of insurance on costs incurred was assessed. The utility of different diagnostic investigations was recorded, and cases were classified according to the final diagnosis. RESULTS: Only 34.8 per cent of dogs were diagnosed with immune-mediated disease, with most frequent diagnoses being steroid-responsive meningitis and polyarthritis. Treatment 24 hours before referral significantly increased the time to diagnosis (P = 0.004) and affected the presence of fever at referral (P = 0.006). Insurance status did not significantly affect cost incurred by the owner. CLINICAL SIGNIFICANCE: This study documents a high incidence of immune-mediated disease in dogs referred for investigation of fever. It also documents a higher incidence of inflammatory central nervous system disease in febrile dogs than that reported previously. Of the diagnostic modalities employed in the majority of cases, radiography, cytology and bacteriological and fungal cultures (fluids/tissues) were the most useful. It is suggested that treatment is withdrawn or withheld before commencing diagnostic investigation of fever.

Differentiating benign and malignant causes of lymphocytosis in feline bone marrow.

Differentiation of benign and malignant causes of lymphocytosis in blood or bone marrow can be problematic. In the present study, reports of examinations of bone marrow from cats, submitted over an 8-year period, were reviewed to identify cats with increased numbers of small lymphocytes. Of 203 reports reviewed, 12 (5.9%) indicated increased numbers of small lymphocytes. Diagnoses for these cats included chronic lymphocytic leukemia (CLL; n = 2), pure red cell aplasia (PRCA; n = 4), immune-mediated hemolytic anemia (IMHA; n = 3), thymoma (n = 1), cholangiohepatitis (n = 1), and fever of unknown origin (n = 1). Several factors were identified that could be used to differentiate reactive lymphocytosis from CLL. Cats with CLL tended to be older, and lymphocytes were slightly larger and had cleaved or lobulated nuclei. Reactive lymphocytosis was associated with immune-mediated anemias and inflammatory diseases. In reactive lymphocytosis, the proliferating lymphocytes were organized into lymphoid aggregates in bone marrow and were predominately B cells. Alternatively, in CLL and thymoma, the proliferating lymphocytes were diffusely distributed and were predominately T cells. Therefore, differentiation of the causes of lymphocytosis should include evaluation of signalment, concurrent disease conditions, lymphocyte morphology, lymphocyte distribution in bone marrow, and immunophenotype. Cat age, presence of severe anemia, and evidence of inflammatory disease also should be considered.

Molecular and serologic evidence of Anaplasma phagocytophilum infection in cats in North America.

Anaplasma phagocytophilum DNA was detected in blood of clinically ill cats from Massachusetts (n = 4) and Connecticut (1) by use of polymerase chain reaction assay and DNA sequencing. All 5 cats were allowed outdoors, and Ixodes scapularis were found on 3 cats. Clinical signs of fever, anorexia, and lethargy resolved quickly after treatment with doxycycline or tetracycline. Serum samples from each cat reacted with A. phagocytophilum morulae via an indirect fluorescent antibody assay; positive antibody titers persisted even after 21 to 30 days of treatment with tetracycline. To the authors' knowledge, this is the first report of A. phagocytophilum infection of domestic cats in North America. Results suggest that infection with the organism may be associated with clinical illness in some cats.

Recurrent fever as the only or predominant clinical sign in four dogs and one cat with congenital portosystemic vascular anomalies.

Fever is not considered a typical clinical sign in animals with portosystemic vascular anomalies (PSVA). In a time period of 8 years, PSVA was diagnosed in 23 cases (20 dogs, 3 cats) at the Animal Hospital of the University of Zurich. Of these, recurrent fever was the only, the predominant or an early sign in 5 animals. Fever and associated unspecific clinical signs like lethargy, inappetence, and reluctance to move were present for weeks to months before the final diagnosis of PSVA was made. It was the lack of typical and well-known signs of PSVA that obscured and delayed the diagnosis. Therefore, PSVA should be included in the differential diagnosis of animals with fever of unknown origin (FUO).

Immune-mediated fever in the dog. Occurrence of antinuclear antibodies, rheumatoid factor, tumor necrosis factor and interleukin-6 in serum.

Contents of antinuclear antibodies (ANA), rheumatoid factor (RF), tumor necrosis factor (TNF-alpha) and interleukin-6 (IL-6) were measured in serum from 20 dogs with immune-mediated fever. Seven out of 20 patients were ANA positive, 1 out of 20 was positive to antibodies against extractable nuclear antigens (ENA), 1 out of 20 was positive to antibodies against deoxynucleoproteins (DNP), 2 out of 13 were RF positive and none out of 20 patients had antibodies against native DNA in the serum. TNF-alpha was not detected in any serum of 15 dogs with immune-mediated fever, while 10 out of 13 presented with elevated IL-6. The results varied between patients, but the IL-6 level was high in most of them. This indicate a role for IL-6 in the pathogenesis of immune-mediated fever in most cases.

Seroepidemiology of undifferentiated fever in feedlot calves in western Canada.

The relationships between 4 bacterial and 3 viral antibody titers and morbidity (undifferentiated fever (UF)) and mortality were investigated in recently weaned beef calves. Blood samples from 100 animals that required treatment for UF (Cases) and 100 healthy control animals (Controls) were obtained: upon arrival at the feedlot (Arrival), at the time of selection as a Case or Control (Selection), and at approximately 33 d of the feeding period (Convalescent). Seroconversion to Pasteurella haemolytica antileukotoxin was associated with an increased risk of UF (OR = 2.83); however, seroconversion to bovine herpesvirus-1 G-IV glycoprotein was associated with a decreased risk of UF (OR = 0.43). Higher Arrival bovine viral diarrhea virus antibody titer was associated with a decreased risk of UF (OR = 0.83). Increases in Mycoplasma alkalescens antibody titer after Arrival were associated with an increased risk of UF (OR = 1.10). Higher Arrival Haemophilus somnus antibody titer and increases in Haemophilus somnus antibody titer after Arrival were both associated with a decreased risk of UF (OR = 0.76 and OR = 0.78). The odds of overall mortality (OR = 5.09) and hemophilosis mortality (OR = 11.31) in Cases were significantly (P < 0.05) higher than in the Controls. Higher Arrival bovine herpesvirus-1 antibody titer was associated with an increased risk of mortality (OR = 1.30). Protective immunity to Pasteurella haemolytica antileukotoxin, Haemophilus somnus, bovine herpesvirus-1 G-IV glycoprotein, bovine viral diarrhea virus, and Mycoplasma spp. may be necessary to reduce the occurrence of UF. Animals with UF are at an increased risk of overall and hemophilosis mortality.

Inheritance of renal amyloidosis in Chinese Shar-pei dogs.

Renal amyloidosis (RA) and recurrent fever of unknown origin (RFUO) are characteristics of familial Mediterranean fever (FMF), a human disorder inherited as an autosomal-recessive trait. Although no animal model has been established for FMF, a similar syndrome of RFUO and RA has been reported in Chinese Shar-pei (CSP) dogs. This report addresses two questions: (1) Is RA inherited in CSP dogs? (2) If it is, is it possible to hypothesize the type of inheritance involved? Two studies were conducted to answer these questions: a historical cross-sectional comparison, which included CSP and non-CSP dogs with RA; and a prospective study that included CSP dogs with RA, RFUO, or both. The cross-sectional comparison resulted in an odds ratio of 10 for RA in CSP dogs under 7 years of age. The prospective study of 28 dogs with RA or RFUO identified 20 that had RFUO and RA, three with RA alone, and five with RFUO alone. RFUO preceded RA in all cases with both conditions. The RFUO/RA combination was observed in both sexes. Four dogs with RFUO with or without RA were born to parents that either were alive at age 7 or had died because of conditions other than kidney failure/RA. When one parent was known to express one of these conditions, the prevalence of RA was between 25% and 50% among littermates.(ABSTRACT TRUNCATED AT 250 WORDS)