Feline herpesvirus (FHV)
There is only one ‘strain’ FHV and it usually causes severe signs of flu. Thick secretions can block the nose and glue up the eyes, needing careful nursing care and antibiotic cover. Kittens are often very quiet, unable or unwilling to eat and have a high temperature. Some kittens, or adults with preexisting diseases that suppress the immune system (eg FIV, diabetes, cancer chemotherapy or on steroid therapy) may die.
For infected cats, it can take weeks for the signs to improve, and the tissue damage that results from the virus infection can cause severe damage to the delicate respiratory and eye tissues leading to long-term problems such as a chronic rhinitis (snotty nose) or conjunctivitis (runny eyes). Even in cats that recover entirely, those that have been infected by FHV are infected for life, becoming ‘carriers’ of the infection. Cats that are carriers of FHV do not shed virus all the time – it ‘hides’ in the cat and is only shed at times of stress. Known stresses that can start a cat shedding virus include re-homing, going to shows or catteries (including stud), having kittens or lactating.
In studies, carrier cats start to shed virus around one week after the stress and shed the virus for up to 14 days after that. Some cats do show mild signs of flu when they are shedding virus, but many cats have no symptoms at all. It can be hard to detect carrier cats, as they do not shed virus all the time, and a negative swab cannot therefore be taken to mean that the cat is clear.
A positive swab on the other hand does mean that the cat is infected. The virus cannot be eliminated from carrier cats. As an infected queen will usually infect successive litters of kittens, probably the best way to manage cats known to be infected with FHV is to remove them from the breeding population by neutering and re-homing.