82 | The five most vital considerations when caring for dogs with distemper virus

PodcastInfectious diseaseNeurological DiseaseRespiratory DiseaseNursing
Written By Laura Jones

Today we’re talking all about a disease I hope you never see (because it’s awful) - but one that’s hard to spot and even harder to nurse - canine distemper virus.

 

Thankfully, due to vaccination, it’s rare - but we do see it, and when we do, it’s a real challenge.

To care for these patients confidently, and stop the spread of this incredibly contagious disease, we first need to understand it - and that’s what I’m here for today.

In the next 20 minutes or so, we’ll discuss what distemper virus is, how it progresses and the impact it has on our patients, as well as how we spot it early, test for it, and - most importantly - give patients with it the best care we can.

So if the only time you’ve seen distemper mentioned is in your college notes or when discussing vaccinations - listen on, because I’ve got you covered.

Let’s start by looking at what distemper REALLY is.

Distemper is a single-stranded RNA virus belonging to the paramyxovirus family, similar to the human measles virus. It’s a very highly contagious virus affecting both domestic and wild dogs, as well as other canid species like foxes, wolves, skunks and raccoons, worldwide.

It’s a multisystemic disease affecting various body systems, including the respiratory system, urogenital system, gastrointestinal system, immune system and nervous system - meaning we see a wide range of clinical signs in these patients, and making identifying it - especially in the early stages - very challenging!

How is distemper virus spread, and which patients are most at risk?

Like many of our other infectious diseases, distemper primarily spreads through indirect contact (contaminated items or surfaces) as well as - less commonly - directly from an infected patient to a susceptible host.

Inhalation of aerosolised droplets from coughing and sneezing is the main route of transmission. However, infected patients will also shed the virus in urine, faeces, saliva, and even in their skin. This shedding can persist for weeks after the patient recovers and their clinical signs stop, so careful infection control and client education and advice are essential nursing considerations for these patients.

In most cases, infection is rare - particularly in areas with widespread vaccination or without a large population of street dogs or wildlife. However, areas with large volumes of unvaccinated dogs, street dogs, or foxes (for example) will have a higher proportion of infected patients. There is also some suggestion that imported dogs can increase the frequency of distemper infection in the UK, particularly in dogs imported from areas of eastern Europe.

Patients at the greatest risk of infection are:

  • Unvaccinated or partially/incompletely vaccinated dogs

  • Rescue centres and shelter populations

  • Immunocompromised patients

  • Young dogs - most cases are seen in dogs under 1 year of age

And, even in vaccinated areas, there’s always a chance of vaccination failure - so we do need to bear this in mind. Maternal antibodies, for example, can interfere with immunity when dogs are vaccinated at a young age, leaving them vulnerable to infection (if their ongoing vaccines are not administered).

So when our patient gets distemper, what happens? How does it affect them, and what clinical signs do we see?

The virus enters the body by inhalation and begins to replicate in the lymphatic tissue in the respiratory tract.

The virus rapidly affects the lymphatic tissues within the body, before it infects the other body systems we’ve already mentioned - the GI tract, the respiratory system, the central nervous system, and the optic nerves.

One of the first things it causes is a biphasic pyrexia - so a period of pyrexia, then a period of normothermia, and then another period of pyrexia. This usually occurs around 3-6 days after initial infection, and can be quite easy to miss, especially if you assess the patient in the dip between their two spikes in temperature.

Usually, by the time the pyrexia recurs, patients also develop respiratory signs, including bilateral serous nasal discharge, mucopurulent ocular discharge, coughing, pneumonia, and, in severe cases, hypoxaemia and respiratory distress.

In this acute period of infection, patients commonly have concurrent GI signs including vomiting, diarrhoea and anorexia, alongside lethargy, dehydration and weakness.

Patients who survive this acute phase of disease (which, sadly, is rare, as the mortality rate is around 80%) will develop chronic signs, including dermatological and neurological signs.

And what signs do we see in the chronic stages of distemper?

Patients can develop hyperkeratosis of the nose and paw pads, leading to the nickname ‘hard pad disease’. As these patients lay down more and more keratin on their nose and pads, these areas become thickened, hard, and are prone to cracking, pain, and secondary bacterial infection.

Alongside this, secondary skin infections, pustules and dermatitis can be seen - many of which will rupture, leaving scarring. Many dogs with distemper have classic white pustules and alopecia on their ventral abdomen, especially.

Immunological signs are also seen in chronic distemper cases. A lymphopenia (low lymphocyte count) is commonly documented, meaning these patients are at increased risk of developing further infection in the hospital.

Some of the most classic chronic distemper signs are neurological. These include:

  • Myoclonus (repetitive, rhythmic muscle contraction, even when resting - I’ve seen quite a few distemper patients do this with their facial muscles, to the extent that they can’t unclench their jaws - making feeding these patients virtually impossible!)

  • Focal or generalised seizures

  • Ataxia

  • Nystagmus

  • Circling

  • Head tilt

  • Blindness

  • Behavioural changes

  • Mentation changes

We may see these neurological signs early in a patient’s infection, but they can also appear months after their initial systemic signs resolve - so advising your clients accordingly (so that they can prevent further transmission) is really important.

So with all of this considered, we can see why distemper is easy to miss - particularly in the early stages of disease. How many patients present with lethargy, dehydration, GI signs, anorexia and respiratory changes? Lots, right? And virtually none of them have distemper… this disease is great at mimicking parvovirus, kennel cough, and meningitis - so have it in the back of your mind if your patient’s circumstances fit.

How do we diagnose these patients?

Distemper should be considered in dogs presenting with pyrexia alongside respiratory, GI and/or neurological signs - especially if they’re unvaccinated, or their vaccination status is unknown.

In these patients, confirmatory testing is performed for diagnosis, and just like our other infectious diseases, there are lots of different testing methods, each with their own considerations.

Antibody testing determines whether the patient has previous exposure to distemper virus - but it doesn’t determine whether that exposure is from vaccination (which it will be in many cases) or actual disease. Because of this, comparing antibody levels between the blood and cerebrospinal fluid is often performed where disease is expected. Patients with natural infection tend to have a higher number of antibodies in the CSF than in the blood.

PCR testing may be used to further rule in or out the disease, depending on the method used. RT-PCR (reverse transcriptase PCR testing) is better at differentiating between natural infection and vaccination-induced immunity.

RT-PCR can be performed on:

  • Smears of the conjunctival, trachea, nasal or genital epithelium

  • A bronchoalveolar lavage or transtracheal wash sample

  • Urine

  • Bone marrow samples

  • And on the buffy coat of the blood, too

Unfortunately, due to the high mortality rates seen with distemper, many patients are diagnosed based on histology at post-mortem.

But we’re not just testing for distemper virus.

Distemper is an awful disease causing severe clinical signs, and we need to manage those - meaning we’ll likely perform biochemistry, haematology and potentially a blood gas too, if you have access to it in practice.

Common changes include haemoconcentration due to dehydration/hypovolaemia, hypokalaemia due to anorexia, and varying changes to oxygenation, ventilation and acid-base depending on the severity of the patient’s respiratory disease. 

These tests will help guide our decision-making around things like fluid therapy rates, potassium supplementation, antibiotics to manage secondary infection, and much more.

And speaking of treatment, let’s talk now about how we can support these patients in the hospital.

As with most viral diseases (except for perhaps FIP), we’re not treating the virus itself - instead, we’re supporting our patient and keeping them (as much as we can) in a position where they can fight off the virus themselves.

Nutrition and hydration support, protecting against secondary infections, neurological and respiratory support and intensive monitoring are needed, alongside supportive nursing care.

Commonly-prescribed treatment includes:

  • Broad-spectrum antibiotics, to protect against infection in an immunocompromised patient and manage any secondary infections (eg upper respiratory or skin infections)

  • Crystalloid fluid therapy, with or without additives such as potassium chloride

  • Antipyretic medications (eg paracetamol) where indicated

  • Analgesics where needed based on patient pain assessments and vital signs

  • Anticonvulsant medications where required depending on the patient’s neurological signs

Aside from that? It’s all about nursing.

Patients with distemper virus need a LOT of support from us. The five areas to especially consider include neurological and recumbency care and monitoring, nutrition, respiratory monitoring and support, maintaining fluid balance and infection control.

First, let’s look at nutrition. These patients are likely anorexic, and in severe cases, may be unable to eat due to their neurological signs. Distemper is also a highly catabolic disease - meaning that significant fat and muscle loss is common. Meeting their energy needs is vital - either by supporting them to eat if they’re able to do so themselves, or placing a feeding tube if they can’t.

These patients are often dehydrated, so monitoring their fluid balance is crucial - alongside things like potassium supplementation as needed.

Many patients will have significant respiratory signs, often needing nebulisation to loosen and clear respiratory secretions and oxygen support where needed. Patients with upper respiratory signs will also require cleaning of dried nasal and ocular discharge to maintain comfort.

Neurological patients are also at risk of aspiration, so we’ll need to monitor this carefully - especially if the muscles impacting chewing and swallowing are affected. Keeping these patients comfortable, repositioning them often, preventing ulcers and pressure sores, and managing their eliminations is also vital.

Lastly, we need to think about infection control. Distemper is a highly, highly contagious disease that can easily spread to other patients. Strict isolation is needed - but, of course, if the patient is critically unwell, we need to be able to monitor and care for them appropriately. Keeping them housed in a separate area from other patients is essential - alongside using separate equipment and consumables, wearing full PPE (not just an apron and gloves) and even changing scrub suits if needed after periods of patient exposure.

Client education and support are other crucial areas for us to consider as nurses and technicians.

Distemper is a devastating disease, often in young, recently acquired or rescued dogs. It can be incredibly challenging for their families, so client support is vital. Set honest but kind expectations, and ensure they know how long things like isolation and shedding last so that they can protect any other dogs they may come into contact with.

So there you have it, that’s a quick refresher on all things distemper, and how to support patients with it. Now we’ve gone through it all, I hope you don’t see one - but if you do, you’ve at least now got the skills and the knowledge to do it confidently, and ensure that your patient receives the best possible care.

To recap everything we’ve discussed, distemper is a severe, highly contagious multisystemic disease affecting the lymphatic, respiratory, CNS, ocular and gastrointestinal systems. It causes varying signs, including pyrexia, GI signs, respiratory signs and neurological signs - and can be hard to spot. We diagnose these patients using a combination of antibody or PCR testing and clinical findings, and our care is supportive - and with this, of course, there are lots of skills we can use as nurses and technicians.

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
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