Treatment of severe parvoviral enteritis (Proceedings) - Veterinary Healthcare


Treatment of severe parvoviral enteritis (Proceedings)


In dogs with intractable vomiting, metoclopramide and chlorpromazine may be used together, but only with caution because the potential for side effects may increase. Dogs should be monitored for restlessness, hyperactivity, bizarre behavior, or extreme drowsiness and if any of these signs occur anti-emetic therapy should be discontinued. Intractable vomiting may respond to treatment with the serotonin antagonist odansetron (Zofran, Cerenex Pharmaceuticals, Research Triangle Park, NC; 0.1 - 0.15 mg/kg IV q 6 - 12 h). Although the drug is highly effective and safe, it is also very expensive. Anticholinergic drugs should not be administered to dogs with CPV enteritis, as they increase the potential for gastric atony, ileus, and intussusception of an irritated bowel segment. Dogs with intractable vomiting should always be evaluated for foreign body obstruction or intussusception. Other causes of continued vomiting include reflux esophagitis and acute pancreatitis. Reflux esophagitis may be manifested by signs of drooling, nausea, and exaggerated swallowing motions. Treatment involves administration of a systemic antacid (famotidine 0.5 mg/kg IV or ranitidine 2 mg/kg IV q 12 h) and an oral suspension of sucralfate (1 gram dissolved in 10 ml warm water q 8 h). Ideally, the antacid should be administered 1 - 2 hours after sucralfate. The new antiemetic maripotan (Cerenia, Pfizer, Inc) is not approved for puppies less than 16 weeks, but it has been used off-label by many veterinarians to treat puppies with CPV. The drug inhibits the vomiting center and the chemo-receptor trigger zone, and is less expensive than the serotonin antagonists. The dose is 1 mg/kg SC q 24 h. It can also be diluted with saline and given IV. It has been very effective in the author's hands, and has not been associated with any signs of toxicity.

Aggressive Adjunctive Treatments

Bacterial endotoxemia is believed to be an important factor in the terminal acute shock which occurs in severe cases of CPV. A polyvalent equine origin antiserum against LPS endotoxin is available for use in small animals (SEPTI-serum, Immvac, Inc., Columbia MO 75201). It is recommended that the product be administered over 30 - 60 minutes at the dosage of 4.4 ml/kg and diluted 1:1 with intravenous crystalloid fluids. Antiendotoxin should be most effective if it is administered before antibiotic therapy because circulating plasma LPS concentrations can increase dramatically following antibiotic kill-off of gram negative bacteria. Patients receiving equine origin antiserum must be observed closely during administration for signs of anaphylaxis. If a second administration of antiserum is deemed necessary, it should be given within 5 - 7 days following the initial treatment. After that time, a severe immunologic reaction is more likely to occur.

In one report, the use of recombinant granulocyte colony stimulating factor (rG-CSF) in dogs with leukopenia secondary to CPV enteritis was described. The recommended dosage was 5 - 10 ug/kg per day SC. Animals that responded generally showed an increase in white blood cell count within 24 hours. Unfortunately, there was no increase in survivability with use of this product, and it is very expensive (approximately $130 - $150 to treat a puppy).

Anecdotal reports describe the use of convalescent serum (1.1 - 2.2 ml/kg IV or SC) collected from CPV-recovered dogs in an effort to provide passive immunity to exposed or infected dogs. Research is needed to determine the efficacy and safety of this practice.

The most recent adjunctive therapy to be recommended is oseltamivir (Tamitlo). This product is a neurominidase inhibitor that has anecdotally been reported to reduce the severity of disease in puppies with CPV. Neurominidase is necessary for bacteria to adhere to the intestinal endothelium and penetrate mucin layers. By inhibiting neurominidase, Tamiflu may reduce bacterial translocation, sepsis, and endotoxemia in dogs with CPV. In a study done at Auburn University, dogs with CPV that were treated with Tamiflu had increased weight gain and 100% survival rate compared to dogs that received a placebo (weight loss and 81% survival). The dosage of Tamiflu is 1 mg/lb PO q 12 h. The incidence of vomiting is reduced if the drug is diluted 50:50 with water or chicken broth immediately prior to administration.

Eradication of Intestinal Parasites

The presence of intestinal parasites has been identified as a factor which can exacerbate CPV infection by enhancing intestinal cell turnover and subsequent viral replication. Fecal samples should be evaluated to identify coccidia, Giardia sp, hookworms, roundworms, or whipworms. Appropriate oral therapy can be initiated as soon as vomiting ceases, or ivermectin (250 ug/kg SC) can be given to non-Collie mix dogs.


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