Treating respiratory disease in dogs and cats

Host:

Welcome to the Bova UK Podcast, where we discuss diseases from diagnosis through to management. These podcasts are aimed at registered veterinary surgeons and veterinary nurses. If you’re listening as a pet owner, we always advise that if you have any concerns about your animal, please consult with your local veterinary surgeon.

So welcome this evening, Val. We have Val here from Vet Specialists Online. After graduating from Edinburgh University, Val spent 11 years working in small animal practice before taking an internship at Dick White Referrals. She then completed a three-year residency in small animal medicine at Glasgow Vet School and passed her European Diploma in Small Animal Internal Medicine in 2016. Val is joining us this evening to talk about respiratory disease and the use of doxycycline.

Dr Valerie Lamb:

Thank you.

Host:

To begin, let’s talk about typical use in feline upper respiratory tract infections and where you’d use doxycycline. Which infectious agents are typically involved?

Dr Valerie Lamb:

For feline upper respiratory tract infections—what we typically call cat flu—that’s often viral. Herpesvirus and calicivirus are the main culprits. Then we can get secondary infections with various bacteria like Pasteurella multocida, Escherichia coli, Staphylococcus aureus, and Streptococcus pneumoniae. We can also get primary bacterial infections like Bordetella and Mycoplasma.

For many cats, especially if it’s viral, we just offer supportive care—meloxicam, good nursing, encouraging eating with strong-smelling food. But if they’re really unwell—off food, lethargic, clearly poorly—then I’d start an antibacterial. My first choice is doxycycline. It’s broad-spectrum, covers gram-positives, Bordetella, Mycoplasma, and Chlamydophila.

Host:

And what are the benefits of testing or investigating these cases?

Dr Valerie Lamb:

In general practice, I don’t think we need to investigate initially. If it’s suspected cat flu and the cat is either well or only mildly unwell, I’d trial 10 days of doxycycline. PCR tests for herpes and calicivirus exist, but bacterial culture from the upper respiratory tract can be hard to interpret due to commensals. Also, Mycoplasma won’t grow in standard cultures. I’d only investigate further if they’re not responding or have chronic signs—then I’d consider imaging for chronic rhinitis or turbinate destruction, and possibly viral testing.

Host:

Why should doxycycline be considered a first-line antimicrobial in respiratory tract disease?

Dr Valerie Lamb:

There are multiple reasons. The ISCAID guidelines (in the Journal of Veterinary Internal Medicine — open access) list doxycycline as a first-line for many upper respiratory cases. It’s effective against the main suspects—Mycoplasma, Bordetella, Chlamydophila. Also, studies show it outperforms convenience antibiotics like cefovecin (Convenia) in shelter cats. There’s no evidence that fluoroquinolones are better. So doxycycline is an effective, evidence-based choice.

Host:

Most practices display the Protect ME poster. Amoxicillin-clavulanate is often the go-to for many. Doxycycline and amoxicillin-clavulanate are listed at the same level. Based on guidelines, would you say doxycycline is preferable?

Dr Valerie Lamb:

Yes, especially if you’re concerned about Bordetella or Mycoplasma. Doxycycline is a better choice for those organisms and is still broad-spectrum. I think it’s a good first-line option.

Host:

Are there scenarios where doxycycline shouldn’t be used as a first-line treatment?

Dr Valerie Lamb:

If the animal is critically ill—dyspnoeic, needs oxygen, has suspected pneumonia—then they need IV antibiotics. In those cases, I’d reach for amoxicillin-clavulanate.

Host:

For cats, what dose and treatment duration would you typically recommend?

Dr Valerie Lamb:

10 mg/kg once daily, usually for 10 days. There’s no firm evidence for exact duration, but I’d reassess at 7–10 days. If not improved, I might extend to 14 days. Beyond that, I’d consider imaging to investigate turbinate destruction or chronic rhinitis.

Host:

Why is doxycycline often used in chronic idiopathic rhinitis?

Dr Valerie Lamb:

Because it acts as an immunomodulatory antibiotic. It reduces immune overreaction to commensals in the nose. It downregulates inflammatory pathways—interleukin-1 beta, for example—and has shown benefit in sepsis models. So it’s ideal for chronic rhinitis. I’d always start with doxycycline before trying anything else.

Host:

And how long would you treat those cases?

Dr Valerie Lamb:

Start with four weeks alongside a non-steroidal anti-inflammatory. Then reassess. You’re unlikely to cure chronic rhinitis—so sometimes it becomes a long-term or intermittent treatment. A couple of weeks on/off can help. I always dose by mg/m² for accuracy.

Host:

And how about side effects?

Dr Valerie Lamb:

It’s generally well-tolerated. Occasionally we see vomiting, diarrhoea, or inappetence. It can increase liver enzymes, but that usually resolves when stopped. The biggest concern is oesophageal ulceration—especially in cats given doxycycline hyclate tablets. It’s acidic and if not swallowed properly, can cause strictures.

Host:

Are there alternative formulations?

Dr Valerie Lamb:

Yes—doxycycline monohydrate is preferred for cats. It’s less acidic and comes as a palatable paste, which is much easier to administer. Most owners manage well with it.

Host:

Cats are notorious for being difficult to medicate!

Dr Valerie Lamb:

They are. And yes, studies show that tablets can stay longer in the feline oesophagus. That increases the risk. So it makes sense to choose monohydrate paste whenever possible.

Host:

Final take-home messages for GPs treating feline upper respiratory infections?

Dr Valerie Lamb:

If the cat is stable, try supportive care. If not, doxycycline monohydrate is a good first-line option—it’s effective and safer for cats. The cascade allows this under VMD guidance. You’re treating the right pathogens and reducing the risk of harm.

Host:

Thank you so much, Val. That’s been incredibly helpful.

Dr Valerie Lamb:

Thank you very much.