Cats with Avian Influenza exhibit symptoms that can result in death. They are one of the few species that can get
Avian Influenza
Avian influenza, known informally as avian flu or bird flu, is a variety of influenza caused by viruses adapted to birds. . The specific virus that they get is H5N1, which is a subtype of Avian Influenza. In order to get the virus, cats need to be in contact with waterfowl, poultry, or uncooked poultry that are infected.
Two of the main organs that the virus affects are the lungs and liver.
History
The H5N1 virus has been found in China, Thailand, Vietnam, Indonesia, Iraq, Austria, and Germany. Besides being found in domestic cats, the virus has infected a variety of wild cats such as the
Asiatic golden cat
The Asian golden cat (''Catopuma temminckii'') is a medium-sized wild cat native to the northeastern Indian subcontinent, Southeast Asia and China. It has been listed as Near Threatened on the IUCN Red List since 2008, and is threatened by poac ...
, the
clouded leopard,
tigers
The tiger (''Panthera tigris'') is the largest living cat species and a member of the genus ''Panthera''. It is most recognisable for its dark vertical stripes on orange fur with a white underside. An apex predator, it primarily preys on un ...
, and
leopards
The leopard (''Panthera pardus'') is one of the five extant species in the genus ''Panthera'', a member of the cat family, Felidae. It occurs in a wide range in sub-Saharan Africa, in some parts of Western and Central Asia, Southern Russia, a ...
.
H5N1 was first discovered in domestic and wild cats in Asia,
specifically in 2003 in the Thai zoo where two tigers and two leopards died. In 2004, the Thai zoo had 147 tigers that died or were euthanized.
This was then followed by an outbreak in Germany in 2006, where three stray cats were found to be either dying or dead during the peak time of the virus outbreak.
Because the virus infects the lungs of cats, it is one of the preferred model animals to study the effects of H5N1 in humans.
Virus
The most common way a cat can obtain H5N1 is by consuming an infected bird. This has been studied in the 2006 and 2007 cases in Germany and Austria where the strains between the cat and the infected birds were not different between the species.
A cat is able to then transfer the virus via the respiratory tract and the digestive tract to other cats. However, studies suggest that a cat cannot transfer the virus to a dog, and vice versa, while sharing a food bowl.
Though there is no concrete evidence, there is a potential link between the transfer of the virus between poultry, wild birds, and humans.
Once the cat is infected, after an incubation period of 2 to 3 days,
the virus can be found in the respiratory tissues, attached to the type II pneumocytes and alveolar
macrophages
Macrophages (abbreviated as M φ, MΦ or MP) ( el, large eaters, from Greek ''μακρός'' (') = large, ''φαγεῖν'' (') = to eat) are a type of white blood cell of the immune system that engulfs and digests pathogens, such as cancer ce ...
,
as well as the intestinal tissues. There have also been some cases where the virus has been found in the brain and other systems in the body.
As of right now the H5N1 virus has not adapted to transfer in between mammals, but there is a fear that this can occur.
Studies done with cats
One epidemiological study that was performed in Germany and Austria on 171 cats found that less than 1.8% of this population had H5N1. In this same sample population of cats, less than 2.6% had antibodies to H5N1. Even though Germany and Austria are among the countries that have had naturally occurring cases, this study shows that very few cats have contracted the disease.
There have also been studies looking at the
T cell
A T cell is a type of lymphocyte. T cells are one of the important white blood cells of the immune system and play a central role in the adaptive immune response. T cells can be distinguished from other lymphocytes by the presence of a T-cell r ...
s, specifically CD4 and CD8, in the cat after viral infection. Though the mechanism is not fully known, there seems to be an inverse relationship with the amount of T cells present and the amount of infected cells.
Another study to test whether the ALVAC recombinant canarypox virus could prime the immune system in cats was performed. This vaccine has the same
hemagglutinin
In molecular biology, hemagglutinins (or ''haemagglutinin'' in British English) (from the Greek , 'blood' + Latin , 'glue') are receptor-binding membrane fusion glycoproteins produced by viruses in the '' Paramyxoviridae'' family. Hemagglutinins a ...
as the H5N1 virus, and therefore worked on preventing death from two different strains of the virus, HPAIV A/Vietnam/1194/2004 and HPAIV A/Indonesia/05/2005. However, some of the cats that were vaccinated did exhibit hyperthermia and weight loss, and all of the cats did have some disease change (assuming lesions) in their lungs. All of the cats, except one, still excreted the virus even after being vaccinated.
Symptoms
A cat that is infected with a high dose of the virus can show signs of
fever
Fever, also referred to as pyrexia, is defined as having a temperature above the normal range due to an increase in the body's temperature set point. There is not a single agreed-upon upper limit for normal temperature with sources using val ...
,
lethargy
Lethargy is a state of tiredness, sleepiness, weariness, fatigue, sluggishness or lack of energy. It can be accompanied by depression, decreased motivation, or apathy. Lethargy can be a normal response to inadequate sleep, overexertion, overwo ...
, and
dyspnea
Shortness of breath (SOB), also medically known as dyspnea (in AmE) or dyspnoea (in BrE), is an uncomfortable feeling of not being able to breathe well enough. The American Thoracic Society defines it as "a subjective experience of breathing di ...
.
There have even been recorded cases where a cat has neurological symptoms such as circling or
ataxia
Ataxia is a neurological sign consisting of lack of voluntary coordination of muscle movements that can include gait abnormality, speech changes, and abnormalities in eye movements. Ataxia is a clinical manifestation indicating dysfunction of ...
.
In a case in February 2004, a 2-year-old male cat was panting and convulsing on top of having a fever two days prior to death. This cat also had lesions that were identified as renal congestion, pulmonary congestion,
edema, and
pneumonia
Pneumonia is an inflammatory condition of the lung primarily affecting the small air sacs known as alveoli. Symptoms typically include some combination of productive or dry cough, chest pain, fever, and difficulty breathing. The severi ...
. Upon inspection, the cat also had cerebral congestion,
conjunctivitis
Conjunctivitis, also known as pink eye, is inflammation of the outermost layer of the white part of the eye and the inner surface of the eyelid. It makes the eye appear pink or reddish. Pain, burning, scratchiness, or itchiness may occur. The ...
, and
hemorrhaging
Bleeding, hemorrhage, haemorrhage or blood loss, is blood escaping from the circulatory system from damaged blood vessels. Bleeding can occur internally, or externally either through a natural opening such as the mouth, nose, ear, urethra, vag ...
in the
serosae of the intestines.
However, a cat that is infected with a low dose of the virus may not necessarily show symptoms. Though they may be asymptomatic, they can still transfer small amounts of the virus.
Treatment and prevention
Cats can be protected from H5N1 if they are given a vaccination, as mentioned above. However, it was also found that cats can still shed some of the virus but in low numbers.
If a cat is exhibiting symptoms, they should be put into isolation and kept indoors. Then they should be taken to a vet to get tested for the presence of H5N1. If there is a possibility that the cat has Avian Influenza, then there should be extra care when handling the cat.
Some of the precautions include avoiding all direct contact with the cat by wearing gloves, masks, and goggles. Whatever surfaces the cat comes in contact with should be disinfected with standard household cleaners.
Researchers have given tigers an antiviral treatment of Oseltamivir with a dose of 75 mg/60 kg two times a day. The specific dosage was extrapolated from human data, but there hasn't been any data to suggest protection. As with many antiviral treatments, the dosage depends on the species.
References
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Cat diseases