Consideration of a Veterinarian-based Outpatient Protocol for Treatment of Canine Parvoviral EnteritisSeptember 28, 2020
Despite another virus taking center stage for most of 2020, Canine Parvovirus (CPV) season is upon us. CPV is a highly contagious virus that attacks rapidly dividing cells such as intestinal cells, and is a significant cause of morbidity and mortality in young dogs. Reported mortality rates range from 4 to 48% with supportive care and up to 91% in untreated experimentally infected dogs.
Parvovirus Standards of Care
The gold standard of Parvovirus treatment involves continuous, round-the-clock supportive care in an ICU setting. Ideal treatment includes
- Hospitalization for aggressive intravenous fluid therapy (maintenance fluids for pediatric patients is already much higher than adults at around 80-100 mL/kg/day, however many Parvovirus dogs are significantly dehydrated, volume depleted, and experiencing profound ongoing fluid losses via vomiting and diarrhea, oftentimes needing fluid rates of up to 160-220 mL/kg/day or more).
- Intravenous antibiotics, antiemetics and gastroprotectants, analgesia, electrolyte and glucose supplementation, metoclopramide CRI for treatment of the inevitable ileus that so many of our Parvovirus pups develop.
- Deworming treatment as warranted,
- Often placement of a nasogastric tube for aspiration of gastric contents to relieve nausea as well for provision of supplemental enteral nutrition, consideration of ProcalAmine parenteral nutrition supplementation (a 3% amino acid and 3% glycerol solution which provides 0.25 kcal/mL of energy, can be given peripherally, and which can provide between 30-70% of RER).
- Plasma and/or albumin transfusion(s) as warranted.
- And close monitoring of blood pressure as well as lab work parameters, especially albumin, blood glucose, hematocrit, white blood cells, and electrolytes.
Unfortunately, this ideal treatment plan can be financially burdensome, often costing $3,000-5,000, sometimes more depending on length of treatment and severity of illness at the time of treatment.
Every ER and GP clinician alike is aware that while this may be the gold standard, not every owner is willing or financially able to pursue such treatment plan, therefore outpatient treatment plans must be considered. And except for the sickest, most clinically affected parvovirus patients, outpatient treatment may be a viable alternative to the ideal when inpatient care is not financially feasible and the dog is deemed medically suitable for outpatient care.
outcomes related to Outpatient Care
In a 2013 prospective study at Colorado State, CPV positive dogs were randomized to receive either standard inpatient (IP) or a modified veterinarian-based outpatient (OP) treatment protocol. Survival to hospital discharge was 90% in the hospitalized group and 80% in the outpatient group. There was no difference in duration of hospitalization between the two groups. Metabolic disturbances were common in both groups, and in regards to the OP group, 50% of the dogs needed oral dextrose and 60% needed oral potassium supplementation. All 4 dogs who failed the OP protocol (3 died and 1 transferred to the IP protocol due to decline) were less than 4 months of age, and less than 4 kg body weight. This study suggested that younger dogs or dogs of low body weight may not tolerate OP care and therefore may not be ideal candidates for OP protocol.
However, this plan was developed in a controlled hospital setting without the difficulties of owner compliance or other issues related to true outpatient care. In a 2017 retrospective study, for dogs receiving veterinarian-based outpatient treatment in a private practice setting, 97 (75%) dogs survived and 33 (25%) dogs failed to survive for ≥ 3 days after initial diagnosis of parvoviral enteritis. And in a 2020 retrospective study of 95 CPV positive dogs whose owners opted for outpatient care in a shelter based low-income clinic, 79 (83%) survived treatment. In the latter study, an increasing number of days with clinical signs prior to treatment and an increase in percent body weight during treatments were significantly associated with survival. Hypothermia on presentation (T < 98.6 F) was negatively associated with survival. Age was also statistically different between the two groups, with a median age of 2.4 months for dogs who died, and a median age of 4.5 months for survivors.
A modified outpatient protocol:
For those patients who are deemed a good candidate for OP care, and those clients who are dedicated to the task of returning their pets to the clinic twice daily for several days for veterinarian-based OP care, an OP protocol can be a viable alternative to hospitalization as follows:
- TPR, exam, blood work (ideally CBC/Chemistry, at minimum PCV/TS, BG, blood smear)
- Dogs exhibiting hypovolemic shock should have a peripheral IVC placed, followed by intravenous volume resuscitation with crystalloids at 15-45 mL/kg IV, with additional crystalloids or colloids at 2-5 mL/kg administered as needed.
- Stable patients may be provided fluid therapy at 40-60 mL/kg SQ.
- If low blood glucose is identified, bolus 25% dextrose 1-2 mL/kg IV, with recheck BW performed to confirm resolution of hypoglycemia.
- External warming during cardiovascular resuscitation as needed to maintain rectal temperature at 99 degrees.
- Once stabilization is reached based on adequate improvement in perfusion parameters (heart rate, pulse quality, CRT, mucous membrane color, temperature, and mentation), outpatient protocol can be initiated.
- Administer Medications:
- Convenia 8 mg/kg SQ
- Pyrantel pamoate 10 mg/kg PO
- Cerenia 1 mg/kg SQ
- Metoclopramide 0.5 mg/kg SQ
- Famotidine 1 mg/kg SQ
- If painful, Buprenorphine 0.01-0.02 mg/kg IM
Subsequent Visits (ideally Twice Daily):
- TPR, exam, PCV/TS, BG, blood smear
- Administer Medications:
- Cerenia 1 mg/kg SQ q24 hr
- Metoclopramide 0.5 mg/kg q12 hr
- Famotidine 1 mg/kg SQ q24 hr or 0.5 mg/kg SQ q12 hr
- If Pt vomiting >3 times since last visit, rescue antiemetic protocol: Ondansetron 0.5 mg/kg SQ, to be repeated as needed according to the vomiting criteria
- If painful, Buprenorphine 0.01-0.02 mg/kg IM q12 hr
- If BG < 80 mg/dL, supplement with 1-5 mL Karo syrup bucally, to be repeated q4-6 hr
- If K+ < 3.4 mEq/L, supplement with 2 mmol/L(mEq)/4.5kg
- oral potassium supplement q4-6 hr (Tumil-L potassium gluconate)
- Enteral nutrition: If no interest in commercial convalescence diet offered at 1 mL/kg every 6 hours, syringe feed 1-3 mL at a time onto the tongue and allow dog to swallow – if patient is no longer receptive to this or exhibiting worsening nausea, syringe feeding should be stopped until next scheduled feeding attempt owners can be taught to administer syringe feedings at home between scheduled appointments, unless concern arises regarding owner’s inability to perform procedure safely, patient’s risk of aspiration, or other contraindications
- Fluid therapy: 40-60 mL/kg SQ q12 hr
Additional Treatment Options:
Another treatment to consider which is easy to administer in an OP setting is fecal microbiota transplant (FMT), using 10 grams of feces from a healthy dog diluted in 10mL of saline and administered rectally using a red rubber catheter and deposited into the proximal portion of the rectum.
In a clinical trial of CPV positive dogs receiving either standard Parvovirus treatment (STD) vs standard treatment plus FMT, among survivors treatment with FMT was associated with faster resolution of diarrhea, shorter duration of hospitalization, and 36.4% mortality in the STD group compared to 21.2% in puppies treated with FMT. FMT can be repeated every 48 hours during a CPV dog’s treatment. Donor feces can be collected and frozen in 10g aliquots for future use, making this an easy addition to any parvovirus protocol.
Failure to respond to outpatient protocol should be evaluated daily, and recommendation of inpatient hospitalization or humane euthanasia should be considered as warranted. This may include:
- Development of stuporous or obtunded mentation.
- Decline in body condition,
- Hyperlactatemia >4 mmol/L.
- Fever of >104 degrees
- Uncontrolled hemorrhagic diarrhea
- Intractable emesis
- >10% dehydration or loss of >10% body weight for 2 consecutive appointments
- or other subjective criteria for decline.
Given the 75-83% success rates reported for outpatient protocols, this can provide a viable option for the right patients and dedicated owners. Clinicians should note the 20-25% mortality rate of dogs with parvoviral enteritis that receive outpatient care when discussing treatment options with owners who are financially unable to pursue hospitalization. Additionally, success of an OP protocol still requires diligent monitoring (TPR, body weight, dehydration status, nausea, pain, blood work parameters) and follow-up assessments by a veterinarian to ensure they are responding appropriately.
- Olan N and Prittie J. Retrospective evaluation of ProcalAmine administration in a population of hospitalized ICU dogs: 36 cases (2010-2013). J Vet Emerg Crit Care 2015; 25(3):405-412.
- Pereira G, Gomes L, Santos I, Alfieri A, Weese JS, and Costa M. Fecal microbiota transplantation in puppies with canine parvovirus infection. J Vet Intern Med. 2018; 32: 707-711.
- Perley K, Burns C, Maquire C, Shen V, Joffe E, Stefanovski D, et al. Retrospective evaluation of outpatient canine parvovirus treatment in a shelter-based low-cost urban clinic. J Vet Emerg Crit Care. 2020: 1-7.
- Prettie J. Canine parvovirus enteritis: a review of diagnosis, management, and prevention. J Vet Emerg Crit Care. 2004; 14(3): 167-176.
- Sarpong K et al. Evaluation of mortality rate and predictors of outcome in dogs receiving outpatient treatment for parvoviral enteritis. J Am Vet Med Assoc. 2017 Nov 1;251(9):1035-1041.
- Venn E, Preisner K, Boscan P, Twedt D, and Sullivan L. Evaluation of an outpatient protocol in the treatment of canine parvoviral enteritis. J Vet Emerg Crit Care. 2017; 27(1): 52-65.