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

PodcastFeline MedicineInfectious diseaseHaematology
Written By Laura Jones

We see anaemia in cats pretty frequently, but it isn’t always down to things like IMHA or haemorrhage.

 

There are infectious causes as well, and we need to be aware of them as veterinary nurses and technicians, so we can care for our patients well (and confidently!) and advise our clients accordingly.

The main one we think about in cats is feline infectious anaemia, aka haemoplasmosis - and that’s exactly what we’ll be discussing today.

So if you’ve ever felt a little unsure when managing an anaemic cat, or wondered why your vet is treating anaemia with antibiotics, we’ll dive into it all in this episode.

Starting, of course, with what FIA is, and how our patients get it.

Feline infectious anaemia, or FIA, or haemoplasmosis, is an infectious disease caused by a group of tiny bacteria called haemoplasmas. We might not think about it that often (unless you see a LOT of anaemic patients), but it’s relatively common, with prevalences of up to 26-27% of cats reported.

There are three types of haemoplasma, and the main culprit is Mycoplasma haemofelis.

Mycoplasma bacteria are very small, lack a cell wall, and are resistant to many antibiotics, meaning we need to use specific ones to treat them - our ‘normal’ antibiotics, like amoxiclav, won’t touch them.

It’s worth mentioning here that different types of Mycoplasma bacteria affect our patients. If you’ve listened to our episode on cat ‘flu, episode 66 (in our respiratory series), you’ll know that Mycoplasma infection can also cause upper respiratory signs. 

This is a different type of Mycoplasma, specifically Mycoplasma felis, a non-haemotrophic species. Today, we’re talking about Mycoplasma haemofelis - sounds similar (because veterinary medicine likes to make things complicated!) but it’s in fact very different.

Though Mycoplasma haemofelis causes most cases of FIA, there are a couple of other bacteria that can cause disease, specifically Candidatus Mycoplasma haemominutum and Candidatus Mycoplasma turicensis. These species aren’t as pathogenic, but can cause disease in immunocompromised or otherwise unwell patients.

Regardless of the specific bacteria that infect our patients, the result is the same.

The bacteria attach to the wall of our patients’ red blood cells, induce haemolysis, destroy the cells, and cause often significant anaemia. 

The more red cell destruction, the lower our patients’ oxygen-carrying capacity, and the poorer their perfusion. Ultimately, they’ll present with signs of transfusion-dependence as their anaemia progresses.

OK, so that’s what haemoplasmosis is - but how do our patients get it?

Haemoplasmosis is transmitted in various ways, including through vectors, contaminated blood transfusions, bite wounds, and from queen to kitten.

We had previously thought of this disease as being transmitted mostly via fleas; however, recent studies have shown that the previously reported high infection rates in fleas were likely false.

There are also several risk factors for developing haemoplasmosis.

These include outdoor access, the presence of concurrent diseases that cause immunosuppression (such as FeLV or FIV, as discussed in episode 77), stressful conditions, or other illnesses that cause weakened immunity.

Interestingly, studies have also documented that male cats, non-pedigree cats, and older cats are at an increased risk of infection; however, when younger cats develop the disease, they are usually more severely affected.

Perhaps unsurprisingly, due to the outdoor risk factor, stray cats have a higher incidence of infection, and this is interesting because, whilst we commonly test for things like FeLV and FIV in our strays, we don’t tend to test for other diseases like haemoplasmosis.

Interestingly, cats can become immune after previous infection, but only to the species that infected them.

Studies have documented that patients can become immune to repeat infection with the same haemoplasma species (if they clear the bacteria completely), but not to other haemoplasmas - and, in fact, they can develop more severe disease if infected with a second pathogen.

What signs do we see when a patient gets haemoplasmosis?

Patients with haemoplasmosis present with signs of haemolytic (destructive) anaemia, so think similar to IMHA, though not quite as severe. Remember that cats are the masters of hiding their disease, so many patients (and especially cats with chronic anaemia) will have less severe (or sometimes no) clinical signs, and many patients have vague, non-specific signs initially.

Common clinical signs in a haemoplasmosis patient include:

  • Varying changes in mentation - from mild lethargy to collapse

  • Pale (rarely jaundiced) mucous membranes

  • Weakness

  • Hyporexia

  • Dehydration

  • Weight loss

  • Intermittent pyrexia

Depending on the severity of the patient’s anaemia, they may present with signs of severe cardiovascular compromise/hypoperfusion, including:

  • Tachypnoea (in an attempt to increase oxygen delivery)

  • Tachycardia

  • Bounding pulses

  • Bradycardia

  • Weak pulses

  • Haemic murmurs (where the decreased blood viscosity causes a heart murmur)

Enlarged lymph nodes and an enlarged spleen can sometimes be palpated on physical examination.

If your patient is showing signs of hypoperfusion, they’ll need rapid stabilisation.

And this is an area that we really excel at as nurses and technicians - we’re often the ones triaging these patients, placing IV catheters, running emergency blood panels, discussing with the vet, and doing things like administering crystalloid boluses under their direction, and planning and preparing a blood transfusion - something we’ll come onto when we discuss treatment.

Once the patient is cardiovascularly stable, the next step is to start thinking about diagnosis. While we’re not diagnosing these patients as veterinary nurses and technicians, we’re heavily involved in the process and need to have a good understanding of how to do that.

Let’s talk about the diagnostic tests these patients need.

As these patients are anaemic, we’ll need to prioritise haematology testing, including a blood smear examination, while testing for haemoplasma species specifically.

The tests we’ll perform in these patients include:

  • Complete blood count

  • PCV and total solids

  • Blood smear examination (sometimes you can see haemoplasma species on a smear, though rarely, and just because you can’t see them, doesn’t mean your patient doesn’t have them!)

  • Blood typing

  • (Ideally) cross-matching, and this must be performed if the patient has had blood products previously (unless their first transfusion was within the last 3 days)

  • Haemotrophic mycoplasma species PCR panel

The PCR panel looks for bacterial DNA from not only Mycoplasma haemofelis but also other species causing haemoplasmosis. 

It’s the gold standard method for diagnosing these patients and is performed on whole blood in EDTA at an external lab. However, please ensure that your patient hasn’t received antibiotics before taking the sample, as this can cause false-negative results.

A quick (slightly off-topic) note about blood donors…

In an ideal world, all feline blood donors should have a haemoplasma PCR panel performed before donation to prevent the spread of infection. 

These tests can take a few days to return, so if you need to use your donor in an emergency, you won’t be able to wait for the results. 

This means that the caregiver of your recipient cat ideally needs to be informed of the theoretical risk of (treatable) infection and provide consent to this as part of the transfusion process.

Ok, so your patient has haemoplasmosis. What next?

The good news is that treating Haemoplasma infection is relatively simple. These patients have a 2-4-week course of either doxycycline or pradofloxacin, depending on the individual patient and the clinician’s preference. Doxycycline is usually used as a first-line treatment, as we prefer to keep fluoroquinolones for as-needed cases as part of responsible antibiotic use.

Steroids have also been used in the management of hemoplasmosis, as these patients can develop an immune-mediated haemolytic anaemia (IMHA) secondary to the infection. However, their use is not recommended unless the patient fails to respond to antibiotics.

However, if you’ve got a significantly anaemic patient, they’ll need more than ‘just’ antibiotics to recover.

Transfusion medicine and supportive care are equally as important, and they’re also where we really come into our own as nurses and technicians.

Patients with significant anaemia displaying ‘transfusion triggers’ will need blood.

We prefer to administer packed red blood cells where possible, as these patients have haemolysis and don’t need the extra plasma volume that whole blood provides.

However, this isn’t always possible, since many countries don’t have access to banked feline blood products.

In these cases, a fresh whole blood transfusion is performed, where blood is collected from a healthy donor cat and transfused to the recipient within 4 hours.

Now, transfusions are a whole episode in themselves (and we chatted about them in episode 47, so give that a listen next if you haven’t already), but I’ll sum them up here. And I’ll leave my favourite resource for feline transfusions - the ISFM Consensus Guidelines - in the description box below the episode, so please check those out, too.

A whistle-stop tour of feline blood transfusions

  • Your donor cat (if doing a donation in-house) needs to be aged 1-8 years old, ideally indoor-only, weigh at least 4.5kg, and be in excellent health with no history of disease. They need to have the right temperament for donation and pass pre-donation screening.

  • A maximum of 10-12ml/kg of fresh whole blood should be collected. If you only need the packed cells, you can stand the syringes up in the fridge before administration so the RBCs settle, and then discard most of the plasma before use.

  • Your donor and recipient must be the same blood type - this is essential for cats, and ideally, we’d also crossmatch them to ensure they’re compatible.

  • Transfusions are administered over 4-6 hours (ideally 4), starting at a low rate and then increasing after the first 30-60 minutes, while monitoring the patient carefully for signs of reaction.

  • Parameters to monitor include heart rate, respiratory rate, pulse quality, temperature, mentation, and blood pressure - both before and at regular intervals throughout the transfusion.

What about supportive care?

These patients also benefit from:

  • Oxygen supplementation (in some cases) to improve oxygen delivery

  • Supportive treatments with antiemetics/appetite stimulants if anorexia or inappetence persists

  • Nutritional support

  • Careful monitoring of fluid balance, looking for signs of hypoperfusion, dehydration, or fluid overload

  • And careful monitoring, particularly throughout and shortly after their transfusion.

So there you have it - how to care for patients with haemoplasmosis (aka feline infectious anaemia) easily as a veterinary nurse or technician. 

It can be an intimidating condition, particularly when these patients present as unstable emergencies, but with a careful, step-by-step approach, they do very well.

Our role in caring for these patients is vast, and with that, we have a wide range of skills to utilise. 

Our first priority is to triage them promptly and stabilise their cardiovascular system - either with crystalloid boluses initially or blood products, depending on what is available.

Once they’re stable, we’ll assist with diagnosis, which is usually relatively simple. 

And then, whilst administering treatment with doxycycline, we’ll continue monitoring them carefully, administering transfusions where needed, and providing that all-important supportive care.

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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78 | How to REALLY understand, recognise and successfully care for patients with FIP