Two studies reported in 2003 provide new insight on treatment of canine parvovirus (CPV), which affects more than a million U.S. dogs per year. The severe enteritis, anorexia, vomiting, hemorrhagic diarrhea, and shock carry a fatality rate of 16% to 35%, although intensive therapy has achieved survival rates of 85% to 96%. Traditionally, this difficult condition has been treated with "gut rest"-no food for 24 to 72 hours after vomiting has ceased-reflecting conventional wisdom despite a lack of controlled clinical studies.
One study suggests that treating the disruption of gut barrier function in CPV enteritis by an initial period of starvation withholds the most important stimulus for intestinal growth and repair-the presence of nutrients in the gut lumen-and may prolong the illness. The authors investigated the effect of early enteral nutrition on intestinal permeability, intestinal protein loss, and outcome in CPV enteritis in a randomized, controlled clinical trial. Dogs in the NPO group (n = 15) received no food until vomiting had ceased for 12 hours. Dogs in the enteral nutrition group (n = 15) received early enteral nutrition via nasoesophageal tube from 12 hours after admission. Intestinal permeability and epithelial integrity were assessed by recovery of lactulose and L-rhamnose in urine. Intestinal protein loss was measured by fecal α1-proteinase inhibitor concentrations. Although no significant difference was found between the 2 groups, lactulose was significantly decreased in the enteral nutrition group. Weight gain was significantly higher on all days in the enteral nutrition group than the NPO group. The median time for return of appetite, improvement in general attitude, and day of resolution of vomiting and diarrhea was consistently 1 day less for the enteral nutrition group. Enteral nutrition has the potential to prevent the protein-energy malnutrition seen in CPV patients. However, survival in the enteral nutrition group was not significantly higher than that in the NPO group.
In another study, clinical efficacy of a recombinant feline interferon (IFN) omega was evaluated in a multicentric, double-blind, placebo-controlled trial. Dogs from 1 to 28 months of age were randomly assigned to 2 groups treated intravenously either with IFN (43 dogs) or placebo (49 dogs). Treated animals improved significantly compared with control animals, and only 3 deaths occurred in the IFN group compared with 14 deaths in the placebo group-a 4.4-fold reduction. Prior vaccination status analysis suggested that IFN therapy resulted in a 6.4-fold reduction in mortality in the unvaccinated animals, which is a significant difference compared with vaccinated animals.
COMMENTARY: Treatment of the severely ill parvovirus patient can be a challenge. No true advances in therapy have been forthcoming, aside from recent studies showing that feeding through CPV with a liquid diet could reduce hospitalization by 24 hours. Now another giant step appears to have been taken if the results of the study on IFN can be confirmed in a larger clinical trial. Treatment with IFN really does seem to make a difference.
Effect of early enteral nutrition on intestinal permeability, intestinal protein loss, and outcome in dogs with severe parvoviral enteritis. Mohr AJ, Leisewitz AL, Jacobson LS, et al. J VET INTERN MED 17:791-798, 2003.
Treatment of canine parvoviral enteritis with interferon-omega in a placebo-controlled field trial. de Mari K, Maynard L, Eun HM, Lebreux B. VET REC 152:105-108, 2003.