Key Points for Integrated Prevention and Control of Infectious Canine Hepatitis

Infectious canine hepatitis is an acute infectious disease caused by canine adenovirus infection, characterized by mainly affecting puppies under 1 year of age, often causing acute necrotizing hepatitis, and clinically often co-infecting with canine distemper. This disease occurs almost worldwide and is a common infectious disease of dogs, but is often overlooked or misdiagnosed by owners; therefore, adopting integrated prevention and control measures for this disease is very important for the healthy development of the dog breeding industry.

1 Outbreak situation

A dog-keeping household in Zhaoyuan County purchased 12 meat-purpose growing dogs from elsewhere on July 16, 2003, including 8 Saint Bernards and 4 Great Danes, and it was unclear whether they had been vaccinated against canine hepatitis. After being brought back, they were mixed with the originally kept dogs without isolation observation. On July 28, 1 Saint Bernard fell ill and died the next day; on July 30, another Saint Bernard and 1 Great Dane fell ill and were brought to the station for treatment; on August 4, another Saint Bernard fell ill.

2 Clinical symptoms

The early symptoms of the sick dogs were very similar to canine distemper, manifesting as depression, poor appetite, markedly increased thirst, vomiting, and diarrhea. The abdominal circumference increased, with fluctuation on palpation, horizontal dullness on percussion, and abdominal paracentesis draining a large amount of pale red fluid. Body temperature rose above 40°C and persisted for 3-5 days. The sick dogs had pain in the xiphoid cartilage area; corneal opacity disappeared after 3 days of treatment. Among the treated sick dogs, 1 dog had scrotal edema, and another dog had blood in the vomit and feces and died the next day.

3 Pathological changes

Necropsy of the dead dogs showed abdominal effusion, a layer of fibrin covering the mesentery and liver surface, enlarged and pale liver, edematous and thickened gallbladder wall, congested and enlarged mesenteric lymph nodes, and pinhead-sized hemorrhagic spots visible on the liver surface.

4 Laboratory examination and diagnosis

4.1 Bacteriological examination The heart and liver of the dead dogs were respectively inoculated onto ordinary agar medium and cultured at 37°C for 48 hours before observation; no bacterial growth was seen.

4.2 Histopathological examination After frozen sections of liver tissue were fixed and stained with basic fuchsin, microscopy showed multinucleated giant syncytial cells in the hepatocyte nuclei as intranuclear inclusion bodies, with thickened and deeply stained nuclear membranes and a clear gap between the nuclear membrane and the inclusion bodies.

4.3 Comprehensive diagnostic analysis Through comprehensive judgment based on the above clinical symptoms, necropsy changes, and laboratory examinations of the sick dogs, the 4 affected dogs were definitively diagnosed with infectious hepatitis.

5 Integrated prevention and control

5.1 Prevention and control

Through the diagnosis and treatment of the above 3 sick dogs and analysis of the onset and causes of death of the early dead dogs, based on the actual disease prevention and control practice in the dog breeding industry and our many years of animal epidemic prevention work experience, for dog-keeping households, especially large-scale dog breeding farms (households), the following four points should mainly be done well in dog disease prevention and control.

① Strengthen feeding management, feed complete compound feed and clean water at fixed times and in fixed amounts, and enhance their own disease resistance. Do a good job of sanitation in the kennels and of the dogs themselves, keep the kennels well ventilated, and keep the environment clean; ② Breed, raise, and keep dogs on their own, reducing or eliminating introduced diseases; ③ Carry out immunization with relevant vaccines (bacterins) on time, which is the key measure for preventing infectious diseases; ④ Promptly isolate sick dogs, feed them separately, and treat them as early as possible; at the same time, urgently vaccinate healthy dogs with vaccines (bacterins) related to the occurring disease.

5.2 Treatment

5.2.1 Puncture drainage Perform abdominal paracentesis drainage on sick dogs with relatively large amounts of abdominal effusion. However, be careful not to drain it all at once, so as to avoid a sharp drop in abdominal pressure, causing abdominal organ congestion and massive fluid loss that may lead to collapse of the sick dog. After the fluid is completely drained, inject 6-8 g of Xianfeng VI diluted with water for injection into the abdominal cavity through the puncture needle tube.

5.2.2 Oral diuretics Choose amiloride, 5 mg daily, taken orally in 2 divided doses. Other diuretics should be chosen cautiously to prevent hepatic coma. When taking diuretics, pay attention to stress reactions such as anorexia, vomiting, and dry mouth; if found, the dose may be reduced to 1.0-1.5 mg daily and maintained for 3-4 days.

5.2.3 Blood transfusion therapy Select healthy, immunized canine blood and conduct a three-drop test and a normal saline ratio test with the sick dog to find a suitable blood type, then transfuse 40-60 mL per day to the sick dog for 3 consecutive days.

5.2.4 Fluid replacement therapy Inject intravenously a mixture of 5% glucose 1.0 mL, normal saline 8-10 mL, 10% Vc 0.1-0.5 mL, 2.5% VB6 0.1 mL, and Xianfeng VI 0.2 g per kg body weight once daily for 3 consecutive days. Severely collapsed sick dogs may additionally be given 0.5 g of protein hydrolysate and intramuscular insulin.

6 Summary

For sick dogs with infectious hepatitis, after the above treatment, symptoms are noticeably reduced in about 4 days; at this point blood transfusion and fluid replacement may be stopped, but general symptomatic treatment should be adopted until recovery.

Practice shows that there is no other special effective therapy for infectious canine hepatitis. During treatment, medication should be given according to clinical symptoms and with reference to blood indices, liver function changes, and other factors. For severe sick dogs whose condition continues to worsen during treatment, such as oliguria, bleeding, and coma, adverse factors must be promptly eliminated to prevent secondary infection with other diseases and the occurrence of serious consequences such as hypoglycemia and coagulation disorders. Time must be gained as quickly and as much as possible for the recovery of liver function and the regeneration of liver cells.