Epidemiology, diagnosis, and treatment of blastomycosis in dogs and cats

Blastomycosis is one of the most common systemic fungal diseases in dogs in North America, but it is rarely diagnosed in cats. The typical route of infection is inhalation of aerosolized conidia of Blastomyces dermatitidis. From the respiratory tract, the developing yeast form may disseminate throughout the body and affect multiple organ systems, most commonly the lymphatic, skeletal and central nervous systems, eyes and skin. Disseminated disease often is associated with nonspecific signs of illness including lethargy, inappetence and fever, as well as signs referable to specific organ systems like chronic cough and dyspnea, peripheral lymphadenopathy, endophthalmitis, and central nervous signs. Diagnosis is typically made by detection of Blastomyces dermatitidis yeast in affected tissues by fine-needle aspiration cytology or histopathology. The treatment of choice is itraconazole. Prognosis is fair in dogs without central nervous disease and guarded in cats.     

Clinicopathologic and radiographic features and etiologic agents in cats with histologically confirmed infectious pneumonia: 39 cases (1991-2000)

OBJECTIVE: To determine clinicopathologic and radiographic features and etiologic agents in cats that died as a result of infectious pneumonia. DESIGN: Retrospective study. ANIMALS: 39 cats. PROCEDURE: Medical records of cats in which infectious pneumonia was confirmed by histologic examination of necropsy specimens were reviewed. Signalment, clinical signs, and results of a CBC, viral serologic tests, and thoracic radiography were evaluated. Infectious agents were classified as bacterial, viral, fungal, protozoal, or parasitic. Histologic features (severity, duration, anatomic location, and distribution) were analyzed. RESULTS: Clinical signs referable to the respiratory tract were not detected in 14 of 39 (36%) cats, and results of a CBC (4/18 cats) and radiography (3/13) were unremarkable. Sixteen of 39 (41%) cats lacked clinical signs of systemic illness. Etiologic agents identified included bacteria (n = 21), viruses (11), fungi (6), protozoa (2), and parasites (1). Cats with clinical signs related to the respiratory tract (19/24 [79%] cats) were more likely to have severe histologic changes than cats without signs related to the respiratory system (6/14). Twenty-nine of 38 (76%) cats had histologic evidence of systemic disease, whereas the remaining cats had lesions limited to the respiratory tract. CONCLUSIONS AND CLINICAL RELEVANCE: Infectious pneumonia is uncommon in cats. Cats with infectious pneumonia may lack clinical signs and have unremarkable results for a CBC and thoracic radiography, yet frequently have systemic infections. Therefore, clinicians should maintain an index of suspicion for pneumonia and evaluate the respiratory tract when infection is detected in other organ systems.     

Fungal urinary tract infections in the dog and cat: a retrospective study (2001-2004)

Thirty-five animals (23 dogs, 12 cats) with fungal urinary tract infections (UTIs) were retrospectively studied. Dysuria, hematuria, increased frequency of micturition, anorexia, depression, and pyrexia were the most common clinical signs noted. Seven species of fungi were identified in the affected animals. Candida albicans was the most common isolate. Most animals diagnosed with fungal UTI also had other concurrent urinary tract or medical problems. Lower urinary tract diseases, diabetes mellitus, neoplasia, and renal failure were the most common concurrent or preceding diseases identified. Resolution of fungal UTI occurred in 12 animals that received specific antifungal treatment.     

Clinicopathologic features of an unusual outbreak of cryptococcosis in dogs, cats, ferrets, and a bird: 38 cases (January to July 2003)

OBJECTIVE: To determine clinical and pathologic findings associated with an outbreak of cryptococcosis in an unusual geographic location (British Columbia, Canada). DESIGN: Retrospective study. ANIMALS: 1 pink-fronted cockatoo, 2 ferrets, 20 cats, and 15 dogs. PROCEDURE: A presumptive diagnosis of cryptococcosis was made on the basis of serologic, histopathologic, or cytologic findings, and a definitive diagnosis was made on the basis of culture or immunohistochemical staining. RESULTS: No breed or sex predilections were detected in affected dogs or cats. Eleven cats had neurologic signs, 7 had skin lesions, and 5 had respiratory tract signs. None of 17 cats tested serologically for FeLV yielded positive results; 1 of 17 cats yielded positive results for FIV (western blot). Nine of 15 dogs had neurologic signs, 2 had periorbital swellings, and only 3 had respiratory tract signs initially. Microbiologic culture in 15 cases yielded 2 isolates of Cryptococcus neoformans var grubii (serotype A) and 13 isolates of C. neoformans var gattii (serotype B); all organisms were susceptible to amphotericin B and ketoconazole. Serologic testing had sensitivity of 92% and specificity of 98%. CONCLUSIONS AND CLINICAL RELEVANCE: Serologic titers were beneficial in identifying infection in animals with nonspecific signs, but routine serum biochemical or hematologic parameters were of little value in diagnosis. Most animals had nonspecific CNS signs and represented a diagnostic challenge. Animals that travel to or live in this region and have nonspecific malaise or unusual neurologic signs should be evaluated for cryptococcosis.     

Assessment of infectious organisms associated with chronic rhinosinusitis in cats

OBJECTIVE: To determine detection rates for feline herpesvirus type 1 (FHV-1), Mycoplasma spp, fungi, and bacteria in flush samples and biopsy specimens from the nasal cavities of cats with and without chronic rhinosinusitis (CRS). DESIGN: Prospective study. ANIMALS: 10 CRS-affected cats and 7 cats without signs of respiratory tract disease. PROCEDURES: Nasal flush samples and biopsy specimens were collected from all cats for bacterial (aerobic and anaerobic), fungal, and mycoplasmal cultures; additional biopsy specimens were collected for virus isolation and polymerase chain reaction (PCR) assay (to detect FHV-1 DNA). RESULTS: Aerobic bacteria were detected in flush samples from 5 of 7 control cats; culture of flush samples from CRS-affected cats yielded aerobic bacteria (9/10 cats), anaerobic bacteria (3/10), and Mycoplasma spp (2/10). No fungal organisms were isolated from any cat. Potential pathogens were isolated significantly more often from CRS-affected cats than from control cats. Bacterial culture of biopsy specimens yielded aerobic bacteria (2/7 control cats and 4/10 CRS-affected cats) and anaerobic bacteria (2/10 CRS-affected cats). Although FHV-1 was not detected in nasal biopsy specimens from control or CRS-affected cats, FHV-1 DNA was detected via PCR assay in specimens from 4 of 7 control cats and 3 of 10 CRS-affected cats. CONCLUSIONS AND CLINICAL RELEVANCE: Compared with findings in control cats, anaerobic bacteria, Mycoplasma spp, and a variety of potentially pathogenic organisms were detected more commonly in samples from cats with CRS. In both groups, FHV-1 was detected via PCR assay as a nonviable organism or in noncultivable amounts.     

Transtracheal aspiration in the diagnosis of pulmonary blastomycosis (17 cases: 2000-2005)

Blastomyces dermatitidis is a common etiologic agent of fungal pneumonia in dogs. Definitive diagnosis is based on cytologic demonstration of the organism in affected tissues. Fluid obtained through transtracheal aspiration has previously been reported to have a low diagnostic yield for B. dermatitidis organisms. This retrospective study identified B. dermatitidis organisms in 76% of samples when transtracheal aspiration was performed in 17 nonsedated dogs with pulmonary blastomycosis. Transtracheal aspiration is a noninvasive and simple procedure that should be considered as an early diagnostic test whenever blastomycosis is a differential diagnosis in dogs with pulmonary disease.     

ECHOLARYNGOGRAPHY IN CATS

Twenty-five cats with clinical signs of upper respiratory tract disease and five cats without upper respiratory signs underwent echolaryngography. Direct inspection of the larynx under general anesthesia was undertaken in all cats and used as the 'gold standard' for the diagnosis of laryngeal diseases. The aims were to: (a) establish which anatomic structures of the larynx are visible ultrasonographically in cats without upper respiratory tract disease, (b) establish which laryngeal abnormalities can be detected and accurately localised using ultrasonography and (c) evaluate in which conditions the technique may provide complementary information or an alternative method of investigation. The ultrasound investigation accurately indicated the presence and location of cysts and masses. Abnormal laryngeal movements were also detected, although it was difficult to confirm whether these were unilateral or bilateral. Vocal cord thickening was seen but the underlying cause could not be established with this technique.     

Disseminated Mycobacterium avium infection in young cats: overrepresentation of Abyssinian cats

Disseminated Mycobacterium avium-intracellulare complex (MAC) infection was diagnosed in 10 young cats (1-5 years of age) from Australia or North America between 1995 and 2004. A further two cats with disseminated mycobacteriosis (precise agent not identified) were recognised during this period. Of the 12, 10 were Abyssinian cats, one was a Somali cat and one was a domestic shorthair cat. None of the cats tested positive for either FeLV antigen or FIV antibody. The clinical course of these infections was indolent, with cats typically presenting for weight loss, initially in the face of polyphagia, with a chronicity of up to several months. Additional clinical features included lower respiratory tract signs and peripheral lymphadenomegaly. A marked diffuse interstitial pattern was evident in thoracic radiographs, even in cats without overt respiratory involvement. Hair clipped to perform diagnostic procedures tended to regrow slowly, if at all. Diagnosis was generally made by obtaining representative tissue specimens from mesenteric lymph nodes, liver or kidney at laparotomy, or from a popliteal lymph node. The primary antecedent event was most likely colonisation of either the alimentary or respiratory tract, followed by local invasion and eventual lymphatic and haematogenous dissemination. Nine cases were treated using combination therapy with agents effective for MAC infection in human patients. Two cats are still undergoing initial therapy and have responded. Of the remaining seven, all responded during long courses (5-14 months) of clarithromycin combined with either clofazimine or rifampicin, and a fluoroquinolone or doxycycline. Of these, three cats remain well (with durations between 2 months and 2 years following therapy); two developed recurrent disease (at 3 months and 2 years, respectively, following therapy) and have restarted therapy. The remaining two cats improved 1 year and 5 months, respectively, after diagnosis but ultimately succumbed. The two cats in which therapy was restarted have improved dramatically. Certain lines of Abyssinian and Somali cats likely suffer from a familial immunodeficiency that predisposes them to infection with slow-growing mycobacteria such as MAC.     

Smoke exposure in cats: 22 cases (1986-1997).

OBJECTIVE: To review clinical findings and clinical course for cats exposed to smoke in residential fires and to determine clinical variables that may have prognostic importance. DESIGN: Retrospective study. ANIMALS: 22 cats admitted to our veterinary teaching hospital between 1986 and 1997 with a history of smoke exposure during a residential fire. PROCEDURE: Medical records were reviewed for history, clinical signs, physical examination findings, changes in respiratory tract signs, initial hematologic analysis, treatment, results of thoracic radiography, and outcome. RESULTS: Fifteen of 22 (68%) cats were categorized in the uncomplicated group, 5 (23%) in the complicated group, and 2 (9%) were discharged after a short period because of financial considerations. Twenty (91%) cats survived, but 2 (9%) were euthanatized because of severe respiratory compromise or neurologic changes. Predominant thoracic radiographic changes were diffuse interstitial pattern (6 cats) and focal alveolar pattern (5). The majority (8/13) of cats that were stable or had improved by the day after admission had an uncomplicated clinical course while hospitalized, whereas cats that were worse on the day after admission tended to have a complicated clinical course. CONCLUSIONS AND CLINICAL RELEVANCE: Cats that survive a residential fire and are admitted to a hospital have a good chance to be discharged. Cats that do not have signs of respiratory tract dysfunction at admission probably will not develop severe respiratory complications. For cats with signs of respiratory dysfunction at admission, better prognostic information will be determined by monitoring progression of the respiratory condition on the day after admission.     

Endogenous lipid pneumonia in cats: 24 cases (1985-1998)

OBJECTIVE: To determine clinical signs, radiographic and histologic abnormalities, and concurrent diseases in cats with endogenous lipid pneumonia (EnLP) and to determine the pathologic importance of EnLP in cats. DESIGN: Retrospective study. ANIMALS: 24 cats. PROCEDURE: Medical records of cats in which EnLP was confirmed by histologic examination of necropsy specimens were reviewed. Information collected from the medical records included signalment, body weight, clinical signs, and results of clinicopathologic tests. Thoracic radiographs were reviewed by a radiologist; histologic specimens were reviewed by a pathologist. RESULTS: All cats had nonspecific clinical abnormalities, such as lethargy, anorexia, or weight loss; 16 had signs of respiratory tract disease. All cats had concurrent systemic diseases, and clinicopathologic abnormalities were reflective of these conditions. Nonspecific abnormalities were detected on thoracic radiographs from 9 of 11 cats. Most cats had macroscopic, multifocal, subpleural lesions; inflammatory infiltrates, cholesterol clefts, and multinucleated giant cells were common. Ten cats had an underlying obstructive pulmonary disease that was the likely cause of EnLP. Lesions of EnLP were not considered to be severe enough or extensive enough to be the cause of death in any of these cats. CONCLUSIONS AND CLINICAL RELEVANCE: EnLP is an uncommon respiratory tract disorder of cats with no pathognomonic clinical, laboratory, or radiographic findings. Although EnLP was not the cause of death in any of these cats, results of the present study do suggest that EnLP may be a marker for potentially severe underlying obstructive pulmonary disease.     

Comparison of histologic lesions of endophthalmitis induced by Blastomyces dermatitidis in untreated and treated dogs: 36 cases (1986-2001)

OBJECTIVE: To compare prevalence of organisms and histologic changes in eyes from dogs with blastomycosis that were either untreated or undergoing treatment with itraconazole. DESIGN: Retrospective study. ANIMALS: 36 dogs with endophthalmitis associated with blastomycosis. PROCEDURE: Signalment, results of ophthalmic examination, and duration of treatment with itraconazole were extracted from medical records. Histologic sections from eyes were examined for prevalence and viability (ie, budding) of fungal organisms. A scoring system was devised to assess the degree of inflammation. RESULTS: Clinically, all eyes were blind and had signs of severe endophthalmitis. Histologically, the type and degree of inflammation and prevalence of Blastomyces dermatitidis were not significantly different between dogs treated with itraconazole and untreated dogs or among groups of dogs treated for different time periods (4 to 14, 15 to 28, or 29 to 72 days). Replication of the organisms in vascular tissues as well as avascular spaces in the eyes was similar in treated and untreated dogs. Lens rupture was seen in 12 of 29 (41%) eyes. CONCLUSIONS AND CLINICAL RELEVANCE: Persistence of inflammation in eyes of dogs with naturally occurring blastomycosis is likely attributable to the continued presence of B. dermatitidis, regardless of the duration of treatment with itraconazole. Lens capsule rupture, a common and previously unreported histologic finding, may contribute to cataract formation and continued inflammation.     

Histoplasmosis in dogs and cats

Histoplasma capsulatum is endemic throughout most of the United States with a high prevalence of infections in the Midwest and South. Histoplasmosis is the second most common systemic fungal disease in cats that may be more susceptible than dogs. Infection occurs by inhalation of conidia from the mycelial phase, which subsequently convert to the yeast form. Histoplasma capsulatum is phagocytized and harbored by cells of the mononuclear phagocyte system. Infection may be subclinical or cause clinical pulmonary granulomatous disease or dissemination. Disseminated disease predominantly affects the liver, spleen, gastrointestinal tract, bone and bone marrow, integument, and eyes. Primary gastrointestinal histoplasmosis also occurs. Clinical signs of histoplasmosis often are nonspecific, including chronic wasting, fever, anorexia, respiratory signs, and lameness. Gastrointestinal signs (eg, diarrhea with hematochezia or melena) are common in dogs. The definitive diagnosis is made by identification of the yeast in tissue samples. Itraconazole is the treatment of choice.     

Pharmacokinetics of enrofloxacin and its efficacy in comparison with doxycycline in the treatment of Chlamydophila felis infection in cats with conjunctivitis

The concentrations of enrofloxacin were measured in the tears, saliva and serum of 14 cats with signs of upper respiratory tract infection and eight with no signs, after daily doses of 5 mg/kg. Enrofloxacin concentrations above the minimum inhibitory concentration of Chlamydophila felis were found in the saliva and tears of the cats with and without signs of upper respiratory tract infection. In a prospective randomised clinical trial, the efficacy of enrofloxacin against C. felis infection in cats with conjunctivitis was compared with the efficacy of doxycycline. Twenty-five cats were randomly assigned to treatment with either enrofloxacin or doxycycline for 14 days; 15 of the cats tested positive for C. felis by an immunofluorescent antibody test on conjunctival swabs. The two treatment groups showed equal improvements in the clinical signs of conjunctivitis and C. felis infection status; in each group three cats were still C. felis antigen-positive after the 14-day course of treatment, indicating a persistent infection. No side effects were observed in the cats treated with enrofloxacin.     

Canine systemic fungal infections.

The principal route of infection for the disseminated fungal diseases discussed in this article is inhalation. In some cases, direct wound contamination and ingestion may also have an important role in the pathogenesis of the disease, especially in histoplasmosis. Another common theme of these diseases is the response of the immune system. If the inoculum is small and the animal is not immunocompromised, the infection may be limited to the respiratory tract and may resolve with few or no clinical signs. Dogs are usually presented to the veterinarian when the fungus has disseminated throughout the body via the circulatory or lymphatic systems, thus causing clinical signs secondary to specific organ infection. Draining skin tracts and lymphadenopathy occur in several of the diseases. The ocular location that is frequently affected is the choroid, where the organisms cause cell-mediated chorioretinitis. Early detection of these changes is important for saving vision and for diagnosing the systemic nature of the disease. Treatment is often effective, especially early in the disease, although it is expensive and long-term, with many animals needing over a year of treatment. Sometimes the treatment must continue lifelong. Ocular disease may not respond to treatment even when respiratory and other organ system clinical signs are rapidly improving. This isolation of the eye is similar to that of the CNS and requires regular monitoring of ocular disease, especially in the fundus, to ensure that systemic drugs are penetrating into the eye. Once the disease progresses to the anterior segment, the ocular prognosis worsens. Better penetration of the blood-retinal and blood-aqueous barriers may be achieved with fluconazole when compared with the other antifungal drugs. Secondary inflammatory ocular disease must also be monitored and treated appropriately to prevent scarring, which may cause vision loss or glaucoma.     

Relationship of Lower Urinary Tract Signs to Seropositivity for Feline Immunodeficiency Virus in Cats

A group of 41 cats with signs of lower urinary tract disease was compared to a group of 41 cats without any history of disease for prevalence of seropositivity for feline immunodeficiency virus (FIV). The group of healthy cats was similar in age and gender to the group of cats with signs of lower urinary tract disease. Three of the cats with lower urinary tract disease and one control cat were seropositive for FIV.
This difference was not statistically significant. The most common cause of lower urinary tract signs was idiopathic. Only 7 cats had urinary tract infection, most associated with perineal urethrostomy or catheterization. Six of the cats with bacterial urinary tract infections were FIV negative. J Vet Intern Med 1996;10:34–38. Copyright © 1996 by the American College of Veterinary Internal Medicine .     

Evaluation of serologic and viral detection methods for diagnosing feline herpesvirus-1 infection in cats with acute respiratory tract or chronic ocular disease

OBJECTIVE: To determine the value of virus isolation (VI), immunofluorescent antibody (IFA) assay, serum neutralization (SN), and ELISA for the diagnosis of clinical feline herpesvirus-1 (FHV-1) infection in cats. ANIMALS: 46 clinically normal cats, 17 cats with signs of acute respiratory tract disease, and 38 cats with signs of chronic ocular disease. PROCEDURE: Conjunctival swabs for VI, conjunctival scrapings for IFA testing, and venous blood samples for SN or ELISA testing were obtained from all cats. RESULTS: FHV-1 was detected in 10.9 and 28.3% of clinically normal cats and in 18.2 and 33.3% of cats with FHV-1-associated disease by VI and the IFA assay, respectively. There were no significant differences in the viral detection rate between cats with acute respiratory tract disease and cats with chronic ocular disease or between diseased cats and clinically normal cats; however, FHV-1 was never detected by both methods in clinically normal cats. Overall FHV-1 seroprevalence was 97% when tested by ELISA and 66% when tested by SN. Seroprevalence did not vary significantly among the 3 groups for either serologic test. Magnitude of SN and ELISA titers varied greatly but independently of presence or absence of clinical signs of FHV-1-associated disease. Sensitivity, specificity, and positive and negative predictive values were assessed for VI and the IFA assay--jointly and individually--and for each SN and ELISA titer magnitude. Values never all exceeded 50%. CLINICAL IMPLICATIONS: Because FHV-1 can be detected commonly in clinically normal cats by the IFA assay or VI, neither test appears to aid in the clinical diagnosis of FHV-1 infection. Seroprevalence does not appear to vary between affected and clinically normal cats. SN, ELISA, VI, and the IFA assay appear to be of limited value in the diagnosis of FHV-1-associated disease in cats. Concurrent assessment of the IFA assay and VI results may permit exclusion of FHV-1 as an etiologic agent if results of both tests are negative.     

Clinical, radiographic, and pathologic features of bronchiectasis in cats: 12 cases (1987-1999)

OBJECTIVE: To determine clinical, radiographic, and pathologic features of bronchiectasis in cats. DESIGN: Retrospective study. ANIMALS: 12 cats with histologic evidence of bronchiectasis. PROCEDURE: Information on signalment, body weight, clinical signs of respiratory disease, concurrent diseases, method by which lung tissue specimens were obtained (surgical biopsy or necropsy), and histopathologic findings was obtained by reviewing medical records from January 1987 to June 1999 for cats with confirmation of bronchiectasis by histologic examination. Available thoracic radiographs were reviewed by a board-certified radiologist. RESULTS: Bronchiectasis was most commonly identified in older male cats. Clinical signs referable to the lower portion of the respiratory tract were detected in only 5 cats but, when evident, were usually chronic (duration > 1 year). Radiographic pattern of bronchiectasis was cylindrical in 4 cats, and in 1 of these cats, a saccular pattern was also identified. For most cats, bronchiectasis was detected in a single lung lobe. Radiographic evidence of bronchiectasis was not detected in 2 cats. Concurrent respiratory diseases included chronic bronchitis and bronchiolitis, neoplasia, bronchopneumonia, endogenous lipid pneumonia, and emphysema. CONCLUSIONS AND CLINICAL RELEVANCE: Bronchiectasis appears to be an uncommon respiratory tract disorder that predominantly affects older male cats. Thoracic radiography may not be sensitive for the diagnosis of bronchiectasis in cats. Bronchiectasis in cats appears to be a sequela of chronic inflammatory bronchopulmonary diseases, especially chronic bronchitis, neoplasia, and bronchopneumonia.     

COMPUTED TOMOGRAPHIC FINDINGS OF FUNGAL RHINITIS AND SINUSITIS IN CATS

The computed tomographic (CT) findings of fungal rhinitis/sinusitis in cats were characterized. The CT images of 10 cats ranging in age from 7 to 13 years were examined. The mean age was 10.8 years and all were neutered males. Nasal aspergillosis was diagnosed in five cats, cryptococcosis in three cats, hyalohyphomycosis in one cat, and trichosporonosis in one cat. Bilateral disease was present in eight cats, seven had abnormal soft tissue attenuation in two-thirds of the nasal cavity, and six had turbinate lysis. Seven cats had also lysis of the hard palate, nasal septum, or frontal bone. One cat had lysis of the cribriform plate. Five of the nine cats whose lymph nodes were imaged had lymph node enlargement. There was contrast medium enhancement in the nasal cavity in all cats, with either a primarily peripheral rim or heterogeneous pattern. There appears to be an overlap of clinical signs, age, and CT features of cats with nasal neoplasia and those with fungal rhinitis/sinusitis.