29 Parvovirus infection in a dog
Initial presentation
Acute haemorrhagic diarrhoea and vomiting with some streaks of blood in vomitus
Signalment: 5-month-old entire male Rottweiler puppy, body weight 20.0 kg
Case history
The puppy presented out of hours as an emergency. Thirty-six hours prior to presentation he had become dull. He had started to retch and then to vomit bile stained fluid. This progressed to vomiting blood stained fluid and the presence of diarrhoea. The diarrhoea had become progressively bloody, with both dark digested appearing blood (melaena) and some bright red blood present. There was no mucus in the stools and the puppy did not strain to defecate. The puppy had not eaten since the onset of the vomiting and was also not drinking.
He had been de-wormed with febantel and praziquantel 1 month prior to presentation. He had been vaccinated against parvovirus, adenovirus, parainfluenza and distemper once after the owner obtained him from the breeder at 6 weeks of age. He had not received a booster vaccination. His usual diet was a commercial dry puppy food.
Physical examination
On presentation the puppy was extremely depressed. He had a body condition score of 4/9. His mucous membranes were slightly dry and pale pink, with a capillary refill time of 3 seconds. A skin tent was present. He was drooling, which was thought likely to be due to nausea. His heart rate was 90 beats per minute with somewhat weak peripheral pulses. Respiratory rate was 40 breaths per minute and rectal temperature was 39.6° C. There were bloody faeces present on the thermometer.
Problem list discussion of problems
The puppy’s main problems were acute haemorrhagic diarrhoea and vomiting. While there was some fresh blood present in the faeces, the diarrhoea was thought to be primarily small intestinal in origin. The vomiting and diarrhoea were combined for the differential lists in this puppy as the concurrent onset suggested a single disorder.
Differential diagnosis
Potential causes of acute vomiting and haemorrhagic diarrhoea in this puppy included:
Case work-up
Emergency diagnostic tests and treatment
The puppy was admitted for diagnostic tests and treatment and was housed in an isolation unit to prevent spread of a possibly contagious disease to other animals.
Nursing tip for infectious diseases
With cases of possibly infectious disease, patients should be kept in an area separate from other patients, especially those patients that may be immunocompromised (e.g. on corticosteroids or chemotherapeutic agents, elderly or young patients). Gloves and protective clothing should be worn to handle the patient and the same materials should not be worn when handling other patients. Scrupulous washing of hands and a dip bath or covers for shoes should also be used. When possible, different staff members should handle a potentially infected case than those handling other patients, especially immunocompromised patients. A thermometer should be kept for use in the potentially infected patient only and a cover used on the thermometer. Stethoscopes and any other equipment used should be cleaned after use or kept only for that patient.
Parvovirus may survive outside the host and is resistant to many disinfectants. For parvovirus, kennel cleaning should be done with bleach at 1 : 32 dilution (half cup bleach per gallon water). Also note that hand sanitizers are probably not viricidal since they are alcohol-based.
The puppy was estimated to be approximately 8% dehydrated. A balanced intravenous crystalloid fluid therapy (lactated Ringers) was initiated at 116 ml/hour.
Clinical tip
Calculation of intravenous fluid amounts
Fluid therapy is calculated based on the amounts needed for maintenance, rehydration and to replace ongoing losses. Maintenance requirements are 40 to 60 ml/kg/24 hour. In this puppy, they were calculated as: 20 kg × 60 ml/kg = 1200 ml/24 hour or 50 ml/hour. The upper end of the maintenance requirement was used in this dog as he was a puppy and they have a larger percentage of body weight as fluid compared to increased body fat in adult animals. Usually the lower end is used for large breed dogs.
To correct his hydration over 24 hours, his body weight times his percent dehydration was used: 20 kg × 0.08% = 1.6 l (1600 ml)/24 hours or 66 ml/hour. This was added to the maintenance amount so that the initial fluid rate was 116 ml/hour. The dehydration could also have been corrected in a shorter time period, e.g. 10 to 12 hours with a faster fluid rate (210 ml/hour for 10 hours or 183 ml/hour for 12 hours).
Estimates of the amount of fluid lost in vomiting or diarrhoea may be added to the maintenance plus rehydration rates. The hydration status should be re-evaluated frequently (hourly while on the fast rates) to determine if the rate should be changed and to assess for overhydration.
Clinical tip
Choice of fluids
For rehydration a crystalloid fluid containing some electrolytes is usually appropriate. With dehydration due to diarrhoea and most cases of vomiting (other than those caused by upper gastrointestinal tract obstruction), the patient is in a state of metabolic acidosis due to decreased tissue perfusion. Buffered crystalloid intravenous solutions such as lactated Ringers are more alkalinizing than 0.9% sodium chloride and may help correct the acidosis, although reperfusion of the tissues is the most crucial part of the treatment.
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