Conditions We Diagnose › Infectious Disease Imaging

Imaging Evaluation of Infectious Disease in Dogs & Cats

Infectious diseases in veterinary patients can mimic cancer, cause organ failure, and produce life-threatening neurological signs. Accurate imaging is often the fastest path to the right diagnosis — distinguishing fungal granulomas from tumors, identifying discospondylitis before paralysis occurs, and staging systemic infections that bloodwork alone cannot fully characterize.

Why Imaging Matters for Infectious Disease

Common Misdiagnosis
Fungal granulomas frequently mimic neoplasia on examination — imaging patterns help distinguish the two
Multi-System Involvement
Many infections (blastomycosis, histoplasmosis, coccidiomycosis) affect lungs, bones, eyes, and CNS simultaneously
Treatment Monitoring
Serial imaging tracks antifungal or antimicrobial response over weeks to months of therapy
Regional Risk
Texas and the southern U.S. carry elevated risk for coccidiomycosis, heartworm, pythiosis, Chagas, and Heterobilharzia
Imaging Modalities

Choose Your Imaging Guide

Each modality reveals different aspects of infectious disease. Select a guide below for disease-specific imaging findings, clinical presentations, and case examples from Sage Veterinary Imaging.

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MRI of CNS Infectious Disease

Advanced neuroimaging of fungal, bacterial, protozoal, and viral infections affecting the brain and spinal cord. Includes meningoencephalitis patterns, granuloma characterization, and FIP evaluation.

Cryptococcus Coccidiomycosis Neospora FIP Bacterial Meningitis
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Radiographic Evaluation

Thoracic and skeletal radiography for parasitic, fungal, and bacterial infections. Heartworm staging, pulmonary patterns, discospondylitis evaluation, and osseous lesion characterization.

Heartworm Blastomycosis Histoplasmosis Discospondylitis Hepatozoonosis
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Ultrasound Evaluation

Abdominal ultrasound for GI, hepatic, splenic, and renal manifestations of fungal and parasitic infections. Pythiosis mass characterization, schistosomiasis mineralization patterns, and systemic staging.

Pythiosis Histoplasmosis Cryptococcus Schistosomiasis Mycobacterium
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Coming Soon

CT Evaluation

Cross-sectional CT imaging for nasal and sinus fungal disease, pulmonary nodule characterization, bony lysis evaluation, and thoracic staging of systemic fungal infections.

Aspergillosis Coccidiomycosis Pulmonary Staging Nasal Disease
Disease Categories

Infectious Agents We Evaluate

Veterinary infectious diseases span five major categories. Each presents with distinct imaging signatures that board-certified radiologists use to narrow differentials and guide treatment.

🍄 Fungal Infections

Coccidiomycosis, blastomycosis, histoplasmosis, cryptococcus, aspergillosis, and pythiosis. Often present as granulomatous masses mimicking cancer, pulmonary nodules, or systemic organ involvement. Endemic to specific geographic regions.

🧫 Bacterial Infections

Meningoencephalitis, discospondylitis, empyema, osteomyelitis, and Brucella canis. Sources include hematogenous spread, foreign body migration, surgical site infections, and direct inoculation. Often produce fever, pain, and acute neurological signs.

🐛 Parasitic Infections

Heartworm disease, lungworms, Heterobilharzia (schistosomiasis), hepatozoonosis, and Cuterebra. Range from incidental findings to life-threatening cardiopulmonary and GI disease. Diagnosis often requires combining imaging with specialized lab tests.

🔬 Protozoal Infections

Neospora caninum, Toxoplasma gondii, and Chagas disease (Trypanosoma cruzi). Protozoal organisms can cause devastating CNS disease, myocarditis, and systemic illness. MRI and echocardiography are key diagnostic tools.

🧬 Viral Infections

Feline infectious peritonitis (FIP), canine distemper, and rabies. FIP in particular produces characteristic MRI findings including periventricular enhancement and obstructive hydrocephalus. Early antiviral treatment has transformed FIP prognosis.

🩺 Rickettsial Infections

Ehrlichiosis, anaplasmosis, and Rocky Mountain spotted fever. While primarily diagnosed via serology and PCR, imaging helps evaluate secondary complications including splenic changes, effusions, and meningoencephalitis.

Clinical Significance

When to Image for Infectious Disease

Infectious diseases frequently present with vague clinical signs — fever, weight loss, lethargy, and pain that overlap with dozens of other conditions. Imaging becomes critical in several scenarios:

⚠ Infection vs. Neoplasia

Fungal granulomas (coccidiomycosis, blastomycosis, histoplasmosis) can appear as aggressive bone lesions, pulmonary masses, or intracranial space-occupying lesions that are radiographically indistinguishable from cancer on initial presentation. A board-certified radiologist can identify subtle patterns — such as regional distribution, concurrent sites of involvement, and characteristic enhancement patterns — that shift the differential toward infection rather than neoplasia.

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Fever of Unknown Origin (FUO): When bloodwork and physical exam cannot localize the source, abdominal ultrasound and thoracic radiographs can reveal hepatosplenomegaly, lymphadenopathy, GI wall thickening, or pulmonary infiltrates that point toward specific infections.
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Acute Neurological Signs: Seizures, ataxia, circling, and altered mentation in young to middle-aged patients warrant MRI to distinguish infectious meningoencephalitis from immune-mediated disease (MUE/GME) — a distinction that fundamentally changes treatment from immunosuppression to antimicrobials.
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Chronic Weight Loss and GI Signs: Pythiosis and histoplasmosis can produce segmental bowel wall thickening, loss of wall layering, and mesenteric lymphadenopathy on ultrasound that mimics GI lymphoma or carcinoma. Ultrasound-guided FNA helps differentiate these.
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Treatment Monitoring: Serial radiographs and ultrasound track response to antifungal therapy over weeks to months. Coccidiomycosis bone lesions and blastomycosis pulmonary nodules show measurable changes that guide treatment duration and discontinuation decisions.
Regional Awareness

Geographic Distribution of Key Infections

Many infectious diseases have strong geographic associations. Sage Veterinary Imaging's locations in Texas and Utah place our patients in endemic zones for several important pathogens:

Texas & Gulf Coast

Coccidiomycosis (Valley Fever), heartworm disease, Heterobilharzia americana (canine schistosomiasis), pythiosis, Chagas disease, hepatozoonosis, and Brucella canis. Warm, humid conditions and tick populations drive year-round exposure risk.

Utah & Intermountain West

Coccidiomycosis from desert soils, blastomycosis in patients with travel history, and heartworm in relocated rescue animals. Tick-borne diseases are less common but seen in patients from endemic areas.

Expert Interpretation

Board-Certified Radiologist Review

Every study at Sage Veterinary Imaging is interpreted by a board-certified veterinary radiologist (DACVR) with extensive experience in infectious disease imaging. Our radiologists have presented on infectious disease imaging at national and regional veterinary conferences and have evaluated thousands of cases across endemic regions.

Dr. Jaime Sage, DVM, MS, DACVR

Jaime Sage, DVM, MS, DACVR

Founder & Chief Radiologist, Sage Veterinary Imaging

Dr. Sage has lectured extensively on MRI, radiographic, and ultrasonographic evaluation of infectious disease at conferences including MCVMA. His case-based approach draws from thousands of real patient studies across Texas, where fungal, parasitic, and tick-borne infections are everyday diagnostic challenges.

Suspect an Infectious Disease?

Our board-certified radiologists differentiate infection from neoplasia, stage systemic disease, and monitor treatment response — giving you answers when clinical signs alone cannot.

SVI Round Rock
Round Rock, Texas
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SVI Spring
Spring, Texas
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SVI Sandy
Sandy, Utah
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Frequently Asked Questions

Infectious Disease Imaging FAQ

Many fungal infections — particularly coccidiomycosis, blastomycosis, and histoplasmosis — produce granulomatous masses and bone lesions that look remarkably similar to aggressive tumors. A board-certified radiologist evaluates the pattern of involvement (multifocal vs. solitary, geographic distribution, concurrent organ involvement) and specific imaging characteristics (enhancement patterns on MRI, bone reaction type on radiographs) that help shift the differential. However, definitive diagnosis often requires combining imaging with serology, cytology, or culture.
Fever of unknown origin (FUO) is one of the strongest indications for diagnostic imaging. Abdominal ultrasound can reveal hepatosplenomegaly, lymphadenopathy, or GI wall changes consistent with systemic fungal disease. Thoracic radiographs can identify pulmonary infiltrates or tracheobronchial lymphadenopathy. If neurological signs accompany the fever, MRI of the brain and spine may be warranted. Your veterinarian can help determine which imaging modality is most appropriate based on your pet's specific symptoms and bloodwork results.
Heartworm staging relies primarily on thoracic radiographs and echocardiography. Radiographs evaluate pulmonary artery enlargement and tortuosity, right heart size (reverse "D" cardiomegaly in severe cases), and lung parenchymal changes ranging from pneumonitis to alveolar disease. Echocardiography can directly visualize adult worms in the right heart and main pulmonary artery in severe (Class 4) disease. The American Heartworm Society classifies disease from Class 1 (asymptomatic, minimal radiographic changes) through Class 4 (caval syndrome with worms visible on echo). Radiographic changes from heartworm disease do not fully resolve even after successful treatment.
Sage Veterinary Imaging provides same-day or next-business-day reporting for all modalities. Urgent cases — patients with acute neurological deterioration, respiratory distress, or suspected sepsis — receive expedited reporting. Our radiologists also offer direct consultation with the referring veterinarian to discuss findings and recommended next steps, including which confirmatory tests (serology, PCR, culture, FNA) are most appropriate.
Yes. When abdominal ultrasound identifies suspicious lesions — such as GI wall masses, enlarged lymph nodes, or altered organ architecture — our radiologists can perform ultrasound-guided fine needle aspiration (FNA) during the same appointment. This allows cytologic evaluation for organisms like Histoplasma, Cryptococcus, and Blastomyces, often providing a same-day diagnosis that avoids the need for more invasive surgical biopsy.