80 | Care for parvo and panleukopenia patients confidently with these simple steps

PodcastInfectious diseaseEmergency + Critical CareGastroenterologyNursing
Written By Laura Jones

Today we’re taking a long, hard look at two of the worst infectious diseases we see - parvovirus in dogs, and its not-so-distant cousin, panleukopenia virus in cats.

 

These patients are often critically ill and need a great deal from us as nurses and technicians. In this episode, we’ll explore exactly how these diseases impact our patients and the nursing care and treatment they require so that you can care for these patients with confidence.

We’ll be doing things a little differently to normal in this episode, too - because these viruses are closely related and managed in similar ways - with a few key differences - we’ll spend the episode discussing and comparing them side-by-side so that you know exactly what the differences and considerations are whether you’re nursing a parvo puppy or a panleukopenia kitten.

So let’s waste no time and get stuck straight into what these diseases are, and why they impact our patients so severely.

Let’s start by looking at parvovirus.

Canine parvovirus, or canine parvovirus-2 (CPV2), is a highly contagious viral infection commonly affecting the gastrointestinal system (and other organs) in dogs.

It actually has three strains - A, B, and C - and they’re all highly virulent. Types A and B are common in the UK, whereas Type C is more prevalent in Europe. Regardless of the strain, the transmission route and pathophysiology remain the same.

Parvovirus is transmitted via the faeco-oral route, either directly from infected animals or indirectly through contaminated fomites (e.g., food bowls, water bowls, surfaces, bedding, etc.).

The virus is incredibly resistant and can survive in the environment for up to a year, including in soil and under extreme temperatures. This makes strict barrier nursing and isolation, as well as proper cleaning and disinfection, key considerations when managing patients with this virus.

Once ingested, the virus travels to local lymphoid tissue where it replicates, then moves to its target organs - the GI tract and bone marrow.

CPV specifically targets rapidly dividing cells - and in our patients, these are mostly found within the intestinal crypts (small glands that sit between the villi in the small intestine), bone marrow (which is full of immature blood cells - and this is important to note because it explains the immunocompromise we see in these patients) and the lymphoid tissue. In puppies under two weeks old, it can also affect the myocardium, leading to myocarditis, progressive cardiac injury, or sudden death.

The result? A severely unwell patient with:

  • Bone marrow destruction leading to decreased white blood cell production, immunosuppression, and a significantly decreased risk of fighting off infection, often leading to sepsis.

  • Severe GI signs due to intestinal crypt cell damage, resulting in severe diarrhoea, vomiting, electrolyte and fluid losses, and bacterial translocation, which is where bacteria from the intestinal lumen move into the bloodstream, potentially causing sepsis.

  • Immune dysfunction from lymphoid tissue damage further decreases our patients’ ability to heal, recover, and protect themselves against other pathogens.

And then we have feline panleukopenia virus, aka FPV.

Feline panleukopenia virus is closely related to parvovirus. Like parvo, it targets rapidly dividing cells, including those in the bone marrow, lymphoid tissues, and intestinal crypts. 

The result is similar to parvovirus in dogs: severe leukopenia (as the name suggests), immunosuppression, and gastrointestinal disease, potentially leading to complications such as sepsis.

However, FPV comes with other complications - when kittens are infected in utero or as a neonate, for example, the disease causes cerebellar hypoplasia. In these cases, the cerebellum (the brain’s movement, posture and balance centre) does not form normally. These patients have lifelong incoordination and ataxia as a result.

Like parvovirus, panleukopenia is highly contagious and transmitted via the faeco-oral route, with indirect transmission occurring through contaminated environments, clothing, hands, and equipment. It’s resistant to many household disinfectants, requiring specific disinfectants (like those used in the clinic) to eliminate it.

Ok, so that’s how these diseases affect our patients. What clinical signs do they cause?

Patients with parvovirus typically present as an emergency.

The classic presentation is a young, unvaccinated puppy aged between six weeks and six months, though older dogs can be affected, particularly if they’re unvaccinated or otherwise immunocompromised.

These puppies often present with an acute onset of:

  • Lethargy and profound weakness

  • Anorexia

  • Persistent and profuse vomiting

  • Severe and often haemorrhagic diarrhoea

Not all patients with parvovirus will have haemorrhagic diarrhoea, so the absence of blood does not necessarily exclude parvo. 

Due to the combination of vomiting, diarrhoea, and anorexia, these patients are severely dehydrated on presentation and often hypovolaemic, so when triaging these patients, we need to assess their cardiovascular parameters closely, looking for:

  • Tachycardia with bounding pulses

  • Bradycardia with weak pulses

  • Pale mucous membranes

  • Prolonged capillary refill time

  • Hypotension

  • Hypothermia.


If these signs are seen, we’ll need to prioritise stabilisation ASAP.

In addition to these signs of hypovolaemic shock, evidence of severe dehydration - including tacky or dry mucous membranes, severe skin tenting, and acute weight loss - is present.

Parvo patients are also at high risk of hypoglycaemia due to anorexia, particularly young puppies who have limited energy reserves and are at an increased risk of hypoglycaemia anyway, let alone with parvo on top.

Since the brain is the body’s largest user of glucose, hypoglycaemia predominantly leads to neurological signs. Dull or obtunded mentation and even seizures can be seen in severe cases.

Lastly, due to bone marrow suppression, leukopenia, and destruction of the gut barrier, these patients are at a significant risk of bacterial translocation, as we’ve touched on. This can lead to sepsis and endotoxic shock, causing:

  • Bright red/injected mucous membranes

  • A rapid CRT

  • Bounding pulses and tachycardia progressing to bradycardia as the patient decompensates.

Feline panleukopenia virus causes similar signs.

Like parvo, feline panleukopenia virus predominantly affects kittens, usually between three and five months of age. 

Clinical signs are very similar and often include severe lethargy, anorexia, vomiting, and diarrhoea with evidence of severe dehydration and hypovolaemia. Unlike dogs, hypovolaemic cats are less likely to present with tachycardia and bounding pulses. In general, they cannot compensate for their reduced circulating volume like dogs can, so bradycardia and weak pulses are seen more commonly.

Due to the marked panleukopenia caused by the virus, these patients are also severely immunocompromised, leading to an increased risk of secondary infections and sepsis.

Like dogs, neurological signs such as dull or obtunded mentation and seizures may be observed due to hypoglycaemia. However, different neurological signs may be present if the infection occurred at a very young age and the patient has cerebellar hypoplasia as a result. These patients are ataxic and often exhibit intention tremors instead, which can persist despite treatment.

Regardless of whether you’ve got a parvo puppy or a panleukopenia kitten, if they’re severely unwell, they’ll need prompt stabilisation.

This is an area in which we’re heavily involved as nurses and technicians. Our role includes:

  • Securing IV access, running emergency blood panels and presenting the vet with the results

  • Calculating and administering crystalloid boluses to stabilise hypovolaemia

  • Administering glucose boluses and calculating and preparing CRIs to manage hypoglycaemia

  • Careful warming in hypothermic patients

  • Intensive monitoring of the patient’s cardiovascular parameters, neurological status, and vital signs

  • Administering antibiotics promptly under vet direction where sepsis is suspected

  • Strict barrier nursing to prevent spread within the hospital, whilst allowing the patient to get the care and monitoring their condition requires

And after stabilisation, we’ll be assisting with their diagnosis.

In most cases, these patients are diagnosed based on a combination of signalment and clinical signs in a young puppy or kitten without a partial or complete vaccination history. Alongside this, we’ll perform routine bloodwork, potentially imaging if needed, and confirmatory testing.

In dogs, we’ll see:

  • An often marked leukopenia in most (up to 85%) of cases

  • Hypoalbuminaemia

  • Hyponatraemia

  • Hypokalmaeia

  • Hypochloraemia

  • Hypoglycaemia

  • Acid-base imbalances (eg, metabolic acidosis, metabolic alkalosis) due to diarrhoea or vomiting, respectively.

We’ll likely perform a faecal antigen test (SNAP test) to increase our suspicion of infection. However, like many other infectious disease tests, this isn’t perfect, and won’t be accurate in 100% of cases. 

False positives can occur in recently vaccinated patients. If you’re concerned that your result might not be 100% accurate, or you’ve got a negative SNAP in a very suspicious patient, a PCR test on faeces is recommended for confirmation.

If your patient has parvovirus, diagnostic imaging may not be required, but concurrent complications like intussusception are common due to severe diarrhoea, and ultrasound will help to identify this where present. Thoracic x-rays are also commonly used to check feeding tube placement - but more on that later in the episode.

What about diagnosing panleukopenia?

Similar to our parvo dogs, panleukopenia is diagnosed based on signalment, clinical signs, and haematology and biochemistry. Diagnostic imaging is rarely needed but may be used to exclude other causes of GI disease.

The results typically show:

  • Marked panleukopenia - reduction in all different white blood cell lines

  • Hypoalbuminaemia

  • Electrolyte abnormalities.

You can use in-house faecal antigen testing (canine parvovirus testing), though FPV PCR testing is the gold standard for confirming infection.

Ok, so know you’ve got a patient with parvo or panleukopenia. Let’s talk about the care they’ll need.

Neither disease has a specific treatment. Instead, our focus is on aggressive supportive management, helping to maintain the patient’s health and prevent complications as best we can whilst their immune system clears the virus.

We’ll focus on maintaining perfusion, preventing sepsis, managing gastrointestinal symptoms, and supporting the immune system while the patient recovers.

Treatment for both CPV and FPV includes:

  • Aggressive fluid therapy with crystalloids to maintain hydration and correct hypovolaemia

  • Electrolyte supplementation (particularly potassium) as required based on the patient’s blood results

  • IV glucose supplementation for hypoglycaemic patients

  • Broad-spectrum antibiotics where indicated to manage bacterial translocation and sepsis risk

  • Antiemetics like maropitant or ondansetron to control vomiting and nausea, improving patient comfort, allowing us to administer early nutrition, and reducing the risk of aspiration.

  • Analgesia with opioids if the patient is painful, but avoiding NSAIDs due to the patient’s severe gastrointestinal disease

And then there’s nutrition.

Nutrition, as we know, is an essential area of managing these patients and an area where we truly excel as nurses and technicians.

Historically, feeding was delayed in these patients, but we now know that early enteral nutrition significantly improves morbidity and mortality. Unless patients have severe, uncontrollable vomiting, early feeding should be prioritised.

These patients should have a naso-oesophageal or nasogastric tube placed as soon as they are stable enough. Following this, trickle-feeding them with an easily digestible, energy-dense liquid diet is recommended - even if they won’t tolerate much food, getting SOMETHING to the GI tract will help to nourish the intestinal cells, promote their recovery and function, and prevent further complications like bacterial translocation.

If patients won’t tolerate enough (or any) enteral nutrition - i.e., they have ongoing vomiting, regurgitation, or ileus that prevents enteral feeding - we’ll need to consider parenteral nutrition instead, though this isn’t without risk. 

Our nursing isn’t limited to nutritional support - there are lots of other considerations, too.

These patients require intensive monitoring throughout their hospitalisation, including:

  • Strict barrier nursing and isolation 

  • Intensive fluid balance monitoring

  • Regular assessment of things like vital signs and mentation to detect deterioration early

  • Pain management, as these patients often have abdominal pain from severe gastroenteritis

  • Gentle grooming and elimination care, keeping the patient clean, dry, and comfortable to prevent faecal scalding and further discomfort.

  • Preventing and managing hypothermia through passive and active warming

  • Minimising stress and considering the behavioural considerations of these patients, particularly young puppies and kittens who are hospitalised during a critical time in their development.

Lastly, let’s talk about prevention.

Whilst there’s lots we can do to treat and care for these patients, the preferred option is, of course, that we don’t see them in the first place!

Both panleukopenia virus and parvovirus are highly preventable through vaccination.

For canine parvovirus, modified-live vaccines are core and recommended for all dogs, starting as early as 6 weeks of age, with boosters given until 16 weeks, a further booster at 1 year, and then every 3 years for life.

For feline panleukopenia, vaccination is also core, starting at 8-9 weeks with follow-up doses at intervals until at least 16 weeks, followed by a booster at 1 year and then every 3 years.

And, of course, we, as nurses and technicians, play an essential part in this process as well. We must discuss vaccination protocols during puppy and kitten clinics, and at other times you’re seeing these patients or discussing their care, remembering that this disease isn’t limited to young patients, and regular vaccination is equally important in older patients, particularly those with immunocompromise or concurrent disease.

Did you enjoy this episode? If so, I’d love to hear what you think. Take a screenshot and tag me on Instagram (@vetinternalmedicinenursing) so I can give you a shout-out and share it with a colleague who’d find it helpful!

Thanks for learning with me this week, and I’ll see you next time!

References and Further Reading

Laura Jones
Next

79 | The step-by-step guide to managing feline infectious anaemia confidently as a vet nurse