Discussion on the Application of Interferon in the Treatment of Canine Infectious Hepatitis

Canine infectious hepatitis is an acute septicemic infectious disease caused by adenovirus. It is characterized by central necrosis of hepatic lobules, intranuclear inclusion bodies in hepatic parenchymal cells and cortical cells, and prolonged bleeding time. Canine infectious hepatitis is seriously harmful to dogs and causes significant economic losses to the dog breeding industry. The virus has considerable resistance; under low-temperature conditions, it can survive in soil for a long time, remaining pathogenic after 10-14 d, and can also survive for a relatively long time in kennels. Sick dogs and recovered virus-carrying dogs are the source of infection for this disease, and their blood, secretions and excreta all contain large amounts of virus. Recovered virus-carrying dogs can shed virus in urine for as long as 6-9 months, becoming a dangerous source of infection. Dogs of all ages can be infected, with puppies having the highest morbidity and mortality, while most adults are subclinically infected. Clinically, this disease mainly presents with symptoms of hepatitis and corneal opacity (i.e., blue eye disease). During the treatment of this disease, the author used interferon instead of ribavirin for antiviral therapy, and the results were quite remarkable. The report is as follows.

1 Clinical Symptoms

A total of 11 cases of this disease were admitted to our hospital. A relatively typical case and the symptoms observed are presented here. The affected dog was 7 months old, female. The owner reported that the dog would not eat or drink, had white eyes, vomited, and had diarrhea. Body temperature 40.5°C, pulse 105 beats/min, respiratory rate 37 breaths/min, depressed spirit, complete loss of appetite, thin and weak. Both eyes had conjunctival hyperemia and cyanosis, with mucopurulent discharge; the corneas showed diffuse white opacity, with characteristic hepatitis and blue eye, and obvious visual impairment: heart sounds were weak, lung sounds unchanged, vomiting yellow foamy mucus, passing yellow watery stool, foul-smelling, with blood; compression of the left costal arch elicited biting and crying, with a pain response; urine was scanty and dark yellow, mucous membranes showed varying degrees of jaundice; the gingival area had blood spots and inflammation. The body temperature changes measured from presentation to recovery were as follows: Day 1 40.5°C, Day 2 39.0°C, Day 3 40.0°C, Day 4 40.0°C, Day 5 39.5°C, Day 6 39.0°C. The temperature curve showed a saddle-shaped pattern.

2 Pathological Changes

The liver was mildly enlarged, light brown to blood-colored, with a granular surface, and the hepatic lobules were obviously friable: the spleen was mildly congested and swollen: the intestinal mucosa had fibrinous exudate: the gallbladder wall was thickened, edematous and hemorrhagic, and the entire gallbladder mucosa had fibrin deposition (this is the characteristic lesion of this disease).

3 Diagnosis

A preliminary diagnosis of this disease can be made based on epidemiology, symptoms (characteristic), and pathological changes. For cases with atypical symptoms, laboratory tests (virus isolation, intradermal test, serological reaction and fluorescent antibody test) are required for confirmation.

4 Treatment

The treatment principles for this disease are comprehensive therapy including antiviral, anti-inflammatory, liver protection, fluid supplementation and detoxification.

4.1 Intramuscular injection of alpha-2b interferon 1 million IU, ceftriaxone sodium 60-80 mg/kg, canine triple hyperimmune serum 1-2 mL/kg, etamsylate 50-100 mg/kg, vitamin K 0.5 mL; enema with 150 mL of 0.1% warm KMnO4 solution; for dogs with keratitis, alternate eye drops of 0.5% lidocaine and chloramphenicol eye drops.

4.2 Intravenous drip of compound sodium chloride 30-80 mL/kg, adenosine triphosphate disodium injection 5-20 mg/kg, coenzyme A 30-50 IU/kg, vitamin C 50-100 mg/kg, vitamin B1 and vitamin B12 2 mL each, once daily; after 8 d, 10 dogs recovered.

5 Summary and Discussion

5.1 Based on the characteristic symptoms, an early diagnosis of this disease can be made. Body temperature changes show a "saddle" pattern, corneal opacity (blue eye disease), varying degrees of mucosal jaundice, and laboratory tests show the white blood cell count of affected dogs decreases to 2500-3000 cells/cubic cm, lymphocytes around 36, prolonged clotting time, and protein and bilirubin in the urine. After onset, early diagnosis and timely treatment generally lead to recovery. Because this disease is a viral disease, treatment results in the later stages are not ideal.

5.2 In the above affected dogs, after no other antiviral drugs were used, all 10 treated dogs recovered within 8 d. This fully demonstrates that recombinant artificial interferon has good broad-spectrum antiviral activity and immunomodulatory function, and particularly has certain efficacy against canine viral enteritis, hepatitis and viral influenza. Therefore, interferon has broad application prospects in the treatment of canine viral diseases.

5.3 Interferon (Interferon, abbreviated as IFN) refers to a class of special "glycoproteins" produced by relevant cells of the animal body induced by "interferon inducers." After being produced and released from their producing cells (i.e., "interferon-producing cells"), these glycoprotein interferons can act on other cells of the same species in the animal body, enabling these cells to acquire a fairly broad "immunity."

5.4 The characteristics of interferon action can be summarized as follows.

5.4.1 Interferon is an inducible protein; normal cells generally do not spontaneously produce interferon, and after being triggered by an inducer, the interferon gene is derepressed and expressed.

5.4.2 The interferon system is currently known as the fastest-acting first-line viral defense system, capable of placing the animal body in an antiviral state within a very short time (within minutes), and the animal body has resistance to repeated viral infection for 1-3 weeks.

5.4.3 The antiviral effect of interferon is achieved indirectly by binding to target cell receptors and inducing antiviral proteins (AVP), exerting an inhibitory effect on viruses rather than a killing effect.

5.4.4 Interferon has species specificity, and different viruses and different cells have different sensitivities to interferon.

5.4.5 Type I and Type II interferons exert different effects and cannot substitute for each other.