Canine Parvovirus Infection & Outpatient Monoclonal Antibody Therapy

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Roxy’s Case

Roxy, a 12-week-old female Labrador retriever, was initially presented emergently for vomiting, anorexia, and bloody diarrhea of 1 days’ duration. Roxy had not yet received veterinary care or any vaccines. Her owners reported that she was given several doses of dewormer from their local farm supply store.

On physical examination, Roxy was ≈10% dehydrated, lethargic, and febrile, with a slow capillary refill time. She defecated hemorrhagic, fetid-smelling diarrhea on the examination table. Fecal ELISA point-of-care SNAP test was positive, and Roxy was diagnosed with canine parvovirus infection. A fecal centrifugation float showed no evidence of parasites. CBC revealed moderate lymphopenia and neutropenia. Serum chemistry revealed mild hypoglycemia, hypokalemia, hypochloremia, hypoproteinemia, and azotemia.

Canine Parvovirus

Canine parvovirus is one of the most widely recognized causes of infectious diarrhea in dogs. It is transmitted through feces and fomites and can persist for months to years, depending on the environment.¹ Vaccination is effective; however, dogs and puppies that have not been fully vaccinated are at high risk for severe, sometimes fatal, infection.¹

In the past, treatment for canine parvovirus has been supportive, with no specific therapies available. More recently, Canine Parvovirus Monoclonal Antibody (CPMA) received USDA conditional approval to directly target canine parvovirus and treat the infection.² CPMA targets parvovirus directly and works by selectively binding and blocking parvovirus from entering and destroying enterocytes.³ One IV dose can shorten the disease course and improve patient outcomes.⁴ Further, CPMA carries a high safety profile and has been shown to be well-tolerated in patients as young as 6 weeks of age.⁵

In a placebo-controlled efficacy study, no dogs died from canine parvovirus infection when treated with CPMA as a monotherapy as compared with a 57% mortality rate in placebo-control dogs.⁶ Incidence of severe signs (eg, diarrhea, lymphopenia, fever, inappetence, vomiting) were lower in the CPMA-treatment group as compared with placebo controls.⁷ CPMA-treated dogs also had improved survival times and shorter length of disease as compared with placebo-treated dogs.⁶ Many dogs treated with CPMA also had faster times to resolution of vomiting, inappetence, and lethargy as compared with placebo-treated dogs.⁶

Back to Roxy’s Case

The veterinarian recommended treatment with CPMA and hospitalization with IV fluids and electrolyte support, antiemetics, gastroprotectants, nutritional support, antimicrobials, pain control, and regularly rechecking laboratory values to adjust treatment as needed; however, the owners insisted that they wanted to try to care for Roxy at home, given that inpatient care was financially not an option, despite it offering the best prognosis.

After a lengthy discussion on what homecare would entail, as well as its risks, the owners elected to treat Roxy at home with subcutaneous fluid therapy and an oral treatment regimen. They planned to return with Roxy if her signs did not significantly improve within a few days or if she started worsening. The veterinarian also recommended an injection of CPMA to target the virus itself and hopefully shorten the clinical disease course, which the owners approved. In addition to a single dose of IV CPMA, the owners allowed for IV fluids during her hospital visit to help correct Roxy’s dehydration and provide antimicrobials and antiemetics. Afterward, they elected to administer further supportive care at home.⁸

The veterinarian checked in with Roxy’s owners regularly. Within 2 days of starting therapy, her diarrhea was significantly better. Her vomiting completely resolved within 3 days and her appetite improved as well. As Roxy continued to recover, her energy level returned. Her owners reported that Roxy was completely back to herself in <1 week.

Conclusion

Although no treatment is 100% effective for canine parvovirus, targeted treatment can help improve outcomes. In Roxy’s case, inpatient therapy was declined, despite better outcomes associated with inpatient therapy.⁷ CPMA provided an additional option to improve her chances of survival and shorten the duration of disease, even in an outpatient setting.

Traditional methods of supportive care do not specifically target the virus and often result in intensive labor and extended hospitalization stays. When owners elect to treat patients at home, ensuring appropriate care can be especially difficult. CPMA provides a way to shorten the time of treatment and care as well as a method to target the virus itself, resulting in improved outcomes with a single injection.

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