Symptoms of Feline Enteric Coronavirus Infection

Characteristics of the Feline Enteric Coronavirus

The Feline Enteric Coronavirus (FECV) primarily spreads through the digestive system. Due to the presence of maternal antibodies, kittens younger than 35 days old rarely fall ill. Puppies between 42 and 84 days old may exhibit enteritis symptoms upon infection. Adult cats often show asymptomatic infections, but fatal cases can occur. Infected and asymptomatic cats can shed a large amount of virus through their feces, leading to transmission via the digestive tract.

Clinical Symptoms

FECV commonly affects weaned kittens, leading to symptoms such as elevated body temperature, decreased appetite, vomiting, diarrhea, and anal swelling. In severe cases, dehydration may be observed. Mortality rates are generally low. During the acute phase, there is a decrease in neutrophils in the blood to below 80%.

Pathological Changes

The disease presents similar lesions to those of feline infectious enteritis. Naturally infected kittens may show swollen mesenteric lymph nodes, edematous intestinal walls, and the presence of shed intestinal mucosa in the feces.

Differential Diagnosis

(1) Feline Coronavirus Infection vs. Feline Parvovirus Infection

Both infections present with similar symptoms such as vomiting, diarrhea, depression, and intestinal mucosal congestion, necrosis, and sloughing, along with enlarged and hemorrhagic mesenteric lymph nodes.

Distinguishing features: Parvovirus infections may show nonsuppurative necrosis in the myocardium or endocardium, with soft myocardium. In contrast, FECV infections often result in severe diarrhea with feces that may be white, yellow, green, or brown, sometimes explosive. The stomach mucosa may hemorrhage and slough, and the spleen and gallbladder may become enlarged.

(2) Feline Coronavirus Infection vs. Feline Hepatitis

Both infections cause symptoms such as depression, anorexia, vomiting, diarrhea, and blood in the feces.

Distinguishing features: Feline hepatitis cases may have a body temperature above 41°C for 36 days, with pain in the hepatic area upon palpation. Autopsy reveals enlarged liver with brown or reddish granules on the surface, friable and easily broken. The gallbladder wall thickens, and there is fibrin deposition on the mucosa. Subcutaneous edema is common, and ascites contains blood that clots when exposed to air. Inclusions are found in the nuclei of hepatocytes and sinusoidal endothelial cells. Emulsify, centrifuge the infected organs, and take the supernatant. Use formalin as the antigen for the变态反应, and if there is local redness, swelling, and pain, the result is positive.

(3) Feline Coronavirus Infection vs. Feline Common Gastroenteritis

Both infections present with symptoms such as vomiting, diarrhea, foulsmelling feces with blood, and anorexia.

Distinguishing features: Cases of common feline gastroenteritis may have a body temperature above 41°C, without contagiousness, with tense abdominal walls and tenderness. When gastritis is predominant, the mucosa and conjunctiva may become jaundiced.

(4) Feline Coronavirus Infection vs. Feline Coccidiosis

Both infections may present with symptoms such as a normal body temperature, vomiting, diarrhea, and sometimes blood in the feces.

Distinguishing features: Coccidiosis cases may show progressive weight loss, with occasional vomiting and pale, slightly yellow mucous membranes. Autopsy reveals white nodules on the intestinal mucosa, with cysts within the nodules. Oocysts can be found in the feces using the saturated salt floatation method.

(5) Feline Coronavirus Infection vs. Feline Hemorrhagic Gastroenteritis Syndrome

Both infections present with symptoms such as diarrhea, severe vomiting, foulsmelling feces, anorexia, and depression.

Distinguishing features: Hemorrhagic gastroenteritis cases may suddenly vomit 23 hours before diarrhea, with blood in the vomit, elevated body temperature, and abdominal pain.

Reminders

Intestinal inflammation should raise suspicion for this disease, but diagnosis can be challenging. Detecting the titer of neutralizing antibodies in infected cats can aid in diagnosis. The virus primarily resides in the small intestine and mesenteric lymph nodes, and can be detected using frozen section fluorescent antibody testing. The gold standard for diagnosis is electron microscopy to observe virus particles in the feces of infected cats.

Preventive Measures

(1) Prevention

The virus is widely distributed in cat populations, with many cats showing no clinical symptoms but acting as carriers, shedding the virus through their feces. Therefore, prevention is challenging. Strengthening husbandry management is the fundamental measure for prevention. Regularly maintain the cleanliness of the cat quarters, separate cats of different ages, and provide extra care for weaned kittens that have lost maternal antibody protection to reduce the incidence rate.

(2) Treatment

The treatment principle is timely fluid replacement and symptomatic treatment.

① Antimicrobial and Antiseptic

Berberine, 1015 mg/kg body weight for cats, twice daily;

Ampicillin, 2030 mg/kg body weight for cats, orally, twice to three times daily, or 1020 mg/kg body weight, subcutaneous or intramuscular injection or intravenous infusion, twice to three times daily; or

Supron (Amoxicillin and Clavulanate Potassium Suspension), 0.1 mL/kg body weight for cats, subcutaneous or intramuscular injection, once daily.

② Fluid Replacement

Sodium chloride injection, 5% glucose, and vitamin C.