Mysterious Canine Disease Spreads in Bay Area: Clinical Signs to Watch

Updated February 18, 2026

Veterinary clinics across the San Francisco Bay Area are reporting cases of a mysterious canine disease that appears to be contagious and potentially fatal in some cases. While the causative agent remains unidentified, the consistent clinical presentation demands immediate attention from the veterinary community.

Current Situation

Timeline: Cases first reported February 13, with additional reports through February 18
Geographic Area: San Francisco Bay Area (multiple counties affected)
Affected Species: Dogs (no reports in cats, other species)
Transmission: Appears contagious between dogs

Multiple veterinary practices have independently reported similar clinical presentations, suggesting a common infectious agent rather than isolated incidents.

Clinical Signs to Monitor

Affected dogs typically present with:

Respiratory Signs:

• Persistent, non-productive cough
• Rapid or labored breathing
• Reluctance to exercise
• Open-mouth breathing at rest

Gastrointestinal Signs:

• Acute vomiting (often projectile)
• Diarrhea (watery to bloody)
• Decreased appetite
• Dehydration

Systemic Signs:

• High fever (often >103.5°F)
• Lethargy and depression
• Weakness or collapse in severe cases

Disease progression appears rapid, with some dogs developing severe illness within 24-48 hours of initial symptoms.

Isolation and Safety Protocols

Until the agent is identified, treat suspected cases as highly contagious:

Immediate Actions:

• Isolate suspected cases immediately upon arrival
• Use separate examination rooms with dedicated equipment
• Implement strict PPE protocols (gowns, gloves, masks)
• Limit staff exposure - designate specific personnel when possible

Environmental Controls:

• Disinfect all surfaces with broad-spectrum disinfectants
• Ensure proper ventilation in isolation areas
• Delay appointments for healthy dogs if possible
• Consider separate entrances/exits for suspected cases

Client Communication:

• Inform owners of potential contagion risk
• Recommend isolation at home from other dogs
• Provide clear discharge instructions for monitoring

Differential Diagnoses

While awaiting identification of the causative agent, consider:

Viral Causes:

• Canine influenza (H3N8, H3N2 strains)
• Canine parainfluenza virus
• Canine adenovirus type 2
• Novel respiratory virus (possible new strain)

Bacterial Causes:

• Bordetella bronchiseptica (kennel cough complex)
• Streptococcus zooepidemicus (see recent Oregon outbreak)
• Mycoplasma species
• Secondary bacterial pneumonia

Other Considerations:

• Toxic ingestion (regional environmental exposure)
• Parasitic pneumonia
• Fungal respiratory disease

Diagnostic Approach

Immediate Diagnostics:

• Complete blood count with differential
• Comprehensive chemistry panel
• Arterial blood gas if respiratory distress
• Thoracic radiographs (three views)

Infectious Disease Testing:

• Respiratory PCR panel (include canine influenza, Bordetella, Mycoplasma)
• Fecal parasite examination
• Bacterial culture from tracheal wash (if indicated)

Sample Submission:

• Contact your state veterinary laboratory
• Follow proper sample handling for unknown infectious disease
• Document all clinical findings thoroughly

Treatment Considerations

Supportive Care:

• IV fluid therapy for dehydration
• Oxygen therapy for respiratory distress
• Anti-emetics for persistent vomiting
• Temperature management

Antimicrobial Therapy:

• Broad-spectrum antibiotics pending culture results
• Consider Bordetella-effective agents (doxycycline, fluoroquinolones)
• Avoid immunosuppressive medications until etiology determined

Monitoring:

• Frequent vital sign assessment
• Daily thoracic radiographs if hospitalized
• Serial complete blood counts

The rapid progression seen in some cases necessitates aggressive monitoring and early intervention.

Geographic and Transmission Pattern

Current cases show clustering in specific Bay Area regions, suggesting either:

• Common source exposure (environmental, food, water)
• Dog-to-dog transmission through parks, daycare, or boarding facilities
• Vector-borne transmission (less likely given season)

High-risk locations may include dog parks, training facilities, boarding kennels, and grooming salons in affected areas.

Public Health Considerations

While no human cases have been reported, veterinary staff should maintain appropriate biosecurity until zoonotic potential is ruled out. This includes standard PPE protocols and hand hygiene practices.

Reporting and Communication

Veterinarians should:

• Report suspected cases to local health authorities
• Share information with regional veterinary communities
• Document detailed case presentations for epidemiological tracking
• Maintain client communication about evolving situation

As more information becomes available, diagnostic and treatment protocols will be updated. The veterinary community’s rapid recognition and reporting of this outbreak demonstrates the value of clinical vigilance.

For continuing education on infectious disease recognition and outbreak management, VetOnIt CE offers expert-led courses designed for practicing veterinarians facing emerging health challenges.

This is a developing story. Check back for updates as more information becomes available from veterinary health authorities.