Symptoms of Canine Parainfluenza Virus Infection: What
Characteristics of the Disease
The primary sources of infection are sick dogs or healthy carriers with the virus. Dogs of all ages and breeds are susceptible. Transmission primarily occurs through respiratory droplets, but can also be contactbased, often in conjunction with other pathogens. The disease is most common in puppies, characterized by an acute course, rapid spread, and widespread distribution, affecting dogs globally.
Clinical Symptoms
Infected dogs exhibit sudden onset of symptoms, including reduced appetite, elevated body temperature, coughing, and in the early stages, a large amount of serous or mucous nasal discharge, which may become purulent. Dogs may also experience severe coughing, red and swollen tonsils, decreased appetite, and a general lack of energy. Most dogs recover naturally within 37 days. However, if secondary infections occur, the illness may persist, with coughing lasting for weeks and the possibility of worsening conditions or even death. In recent years, it has been suggested that canine type II parainfluenza virus can also infect brain tissue and the intestines, leading to conditions such as encephalomyelitis, cerebrospinal fluid effusion, and encephalitis. A few affected dogs may only show neurological symptoms like hind limb paralysis and hemorrhagic enteritis.
Pathological Changes
The lungs may show minor hemorrhagic spots; the tonsils, trachea, and bronchi may exhibit inflammatory changes. Dogs that die from enteritis and neurological symptoms may show changes in the intestines, brainstem inflammation, and hydrocephalus.
Differential Diagnosis
1. Canine Parainfluenza Virus Infection vs. Canine Infectious Bronchitis
Both conditions present with coughing, elevated body temperature, and general malaise. The distinction lies in the presence of purulent nasal discharge, paroxysmal dry cough, and vomiting and diarrhea in cases of infectious bronchitis.
2. Canine Parainfluenza Virus Infection vs. Canine Cold
Similar symptoms include coughing, elevated body temperature, and malaise. The cold is more common in changing weather conditions, with clear nasal discharge, sneezing, and a rough respiratory sound on auscultation, along with conjunctival congestion and lacrimation. The throat and trachea are sensitive to touch.
3. Canine Parainfluenza Virus Infection vs. Canine Bronchitis
Both conditions present with coughing, elevated body temperature, purulent nasal discharge, and malaise. The main difference is that bronchitis is characterized by coughing, with initial dry, painful coughs progressing to moist coughs, with serous or purulent nasal discharge. The respiratory sound is enhanced on auscultation, and coughing is chronic, worsening with cold exposure.
4. Canine Parainfluenza Virus Infection vs. Canine Pneumonia
Both conditions present with coughing, elevated body temperature, and malaise. Lobar pneumonia is characterized by coughing, with a body temperature above 40°C, remittent fever, rough respiratory sounds, and dry or wet rales. Chest Xrays show widespread, homogeneous, dense shadows. Pneumonia with lobar consolidation presents with a body temperature above 40°C, persistent fever, iron锈colored nasal discharge, and chest Xrays showing widespread, homogeneous, dense shadows.
5. Canine Parainfluenza Virus Infection vs. Canine Toxoplasmosis
Both conditions present with fever, cough, nasal discharge, and in some cases, paralysis and hemorrhagic diarrhea. The distinction is that toxoplasmosis cases may have purulent ocular discharge, uveitis, and retinitis, with a decrease in red blood cell count and hemoglobin. Pathological examination can detect trophozoites.
6. Canine Parainfluenza Virus Infection vs. Canine Aspergillosis
When aspergillus invades a dog's nasal cavity and paranasal sinuses, the dog may exhibit sneezing and discharge of serous or mucous nasal fluid, similar to symptoms of canine parainfluenza. The distinction is that parainfluenza cases have elevated body temperature, severe coughing, and red and swollen tonsils. Additionally, microscopic examination of nasal secretions and pus may reveal branched, septate hyphae with连锁状 sporangia, leading to a diagnosis of canine aspergillosis.
Advice
A preliminary diagnosis can be made based on the clinical symptoms, epidemiological characteristics, and pathological changes of the disease. Since canine parainfluenza virus infection shares similar symptoms with canine respiratory diseases, laboratory tests should be employed for differential diagnosis.
Preventive Measures
1. Prevention
① Strengthen the management of breeding and environmental hygiene around the kennel.
② New dogs should be quarantined and vaccinated.
③ Isolate and treat infected dogs, and cull severely ill dogs. Vaccinate the rest of the dogs.
Treatment
The treatment principle is antiviral, preventing secondary infections, and symptomatic treatment for cough and expectoration.
① Antiviral therapy
Acyclovir, 510 mg/kg body weight, intravenous infusion, once daily for 10 days;
Ribavirin, 2050 mg/kg body weight, oral administration, once daily for 7 days, or 57 mg/kg body weight, subcutaneous, intramuscular, or intravenous injection, once daily;
Interferon, 1020,000 units per dose, subcutaneous or intramuscular injection, every other day.
② Antibiotic therapy to prevent secondary infections
Ampicillin, 2030 mg/kg body weight, oral administration, 23 times daily, or 1020 mg/kg body weight, subcutaneous, intramuscular, or intravenous injection, 23 times daily;
Cefazolin sodium, 1530 mg/kg body weight, intramuscular or intravenous injection, 34 times daily;
Suprocin (amoxicillin clavulanate potassium suspension), 0.1 mL/kg body weight, subcutaneous or intramuscular injection, once daily;
Enrofloxacin injection, 1 mL/kg body weight, subcutaneous or intramuscular injection, once daily;
Amikacin, 515 mg/kg body weight, subcutaneous injection, 13 times daily.
③ Relieving respiratory symptoms
Aminophylline, 1015 mg/kg body weight, oral administration, 23 times daily, or 50100 mg per dose, intramuscular or intravenous injection;
Phenylephrine, 25 mg per dose, oral administration, 23 times daily.
④ Antiinflammatory therapy
Dexamethasone, 0.5 mg/kg body weight, oral or intramuscular injection, 12 times daily.