While we humans are in the midst of an Influenza Epidemic, we regularly see cats showing very similar symptoms – sneezing, runny noses, sore and runny eyes, a fever and unwillingness to eat. This condition has been called “Cat Flu” and in recent years we’ve seen people worrying about whether they’ll infect their cats – and there have even been reports of people rehoming or, tragically, abandoning their cats to try and protect themselves and their families. So the time seemed right to do a short blog explaining what Cat Flu actually is and how it can be managed!
Do cats get flu?
Strictly speaking, it is possible for cats to contract the flu. There have been a handful of reported cases where cats developed influenza – involving strains H5N1, H3N2, and H1N1. However, this is incredibly rare, and is probably due to cats eating infected birds, having contact with infected dogs, and infected humans, respectively. There are, however, no records of humans ever catching influenza from cats.
In addition, it’s fantastically rare for a cat to contract it! While other species, such as most birds and pigs, easily contract and pass on influenza strains (indeed, the virus is probably a bird virus originally), infection of carnivores (dogs, ferrets and cats) is incredibly rare – and is so uncommon that we don’t even need to consider it in most situations.
So what is Cat Flu?
It’s a complex syndrome caused by four different infectious agents. Its technical names are FURI (Feline Upper Respiratory Infection) and Feline Viral Rhinotracheitis, but most people refer to it as “Cat Flu”, as it clearly describes the symptoms! The four pathogenic agents that cause this syndrome are:
- Feline Herpesvirus. This is probably the most common cause of upper respiratory infections in cats; it also attacks the eyes, causing soreness and runniness, and occasionally ulcers. Like all herpes viruses, though, once a cat is infected they will never clear the virus. Instead, it will go into hibernation (probably in the big nerves of the head and face). While the cat will get better, the virus is still there and later in life, if stressed or ill, the virus can reactivate causing the symptoms to reappear. This is sometimes called “recrudescence” or “viral reactivation”, but is most commonly described as Chronic Cat Flu.
- Feline Calicivirus. This is another very common cause of infections, but usually results in less severe disease. However, this virus rapidly mutates, and there are strains out there that cause “stomatitis” – ulcers of the mouth – and even some that can be life threatening, although these are very uncommon. Cats infected with Calicivirus will usually clear the infection, although it may take many months before they stop spreading the virus.
Between them, these two viruses account for over 90% of all Cat Flu cases.
- Bordetella bronchiseptica is an uncommon, but recognised, cause of symptoms. This is the same bacterium that causes Kennel Cough in dogs, and closely related to the Whooping Cough bug in humans. As you’d expect, it’s the only Cat Flu agent that is commonly associated with coughing as well as sneezing!
- Chlamydophila felis, also known as “Feline Chlamydia”, mainly causes eye symptoms, but can be involved in sore throats as well. It can cause other health problems though, and may be a cause of poor fertility in breeding queens.
How can cat flu be treated?
To some extent it depends on the cause. There are very few treatments available against the two viruses – treatment revolves around managing the symptoms and preventing secondary bacterial infections. It’s important to encourage cats to eat (e.g. with warmed, strong-smelling foods) and drink, and keep them warm and comfortable. In severe cases, vets may prescribe antibiotics to prevent bacteria from taking advantage of the cat’s weakened state.
There is a medical treatment for herpesvirus (aciclovir) but this is quite dangerous in cats, unless used in exactly the right way. More promising is the use of Lysine paste, which is thought to slow down the replication of the virus.
The only veterinary treatment available with a well described protocol for treating these two viruses is a synthetic interferon, that “supercharges” the cat’s immune system, increasing their ability to fight the virus. However, it is very expensive and does have significant side effects in some cats, so it only used for the most severe cases.
Most cats with Cat Flu will recover with good nursing care, and this is therefore the mainstay of treatment.
The bacteria (Bordetella and Chlamydia) can of course be managed with antibiotics, although they are uncommon causes of the disease.
Can it be prevented?
Yes! The best way to protect your cats from Cat Flu is to get them vaccinated. There are fairly good vaccines available against Calicivirus and Herpesvirus, and one against Chlamydia. While they are not perfect, they massively reduce the risk of infection, and the severity if the cat does develop symptoms. In addition, it is thought that vaccinated cats infected with herpes may be able to avoid becoming long-term carriers.