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'&-*/& 3)*/*5*4 611&3 3&41*3"503: %*4&"4& ] Virus Reactivation UÊ LoÕÌÊnä¯ÊovÊV>ÌÃÊiÝ«iÀiinViÊniÕÀon>lÊl>ÌinVÞÊovÊ FHV in the trigeminal ganglion; the virus can then be reactivated due to stress, illness, or immuno- suppression (| 50% of cats).5 UÊ nÌiÀmiÌÌinÌÊÀi>VÌiÛ>ÌionÊovÊ 6Ê}iÛiÃÊÀiÃiÊÌoÊÛiÀ>lÊ shedding in oronasal and conjunctival secretions. UÊ7hinÊÀi>VÌiÛ>ÌionÊiÃÊ>ÃÃoVi>Ìi`ÊÜiÌhÊVliniV>lÊÃi}nÃÊ it is termed recrudescence; however, shedding can occur in the absence of clinical signs in cases of chronic, latent FHV infection. Etiology of Clinical Signs UÊ6iÀ>lÊ 1,/Ê inviVÌionÊ V>nÊ V>ÕÃiÊ iiÌhiÀÊ >VÕÌiÊ oÀÊ chronic clinical signs (Figures 1 and 2), depend- ing on the immune status of the affected cat (and potentially other factors). UÊ nviVÌionÊ iÃÊ >ÃÃoVi>Ìi`ÊÜiÌhÊmÕlÌivoV>lÊ i«iÌhili>lÊ necrosis, neutrophilic inflammation, and fibrin- oÕÃÊiÝÕ`>Ìion]ÊÀiÃÕlÌin}ÊinʺVl>ÃÃiV»ÊVliniV>lÊÃi}nð Prevention UÊ ÌÊiÃÊim«oÀÌ>nÌÊÌoÊnoÌiÊÌh>ÌÊÛ>VViniÃÊ>ÀiÊnoÌÊniViÃ- Ã>ÀilÞÊ «ÀoÌiVÌiÛipÌhiÞÊ >ÀiÊ `iÃi}ni`Ê ÌoÊ `iVÀi>ÃiÊ severity of clinical signs (especially with FCV, due to its great antigenic diversity).6 UÊ1,/Ê ÛiÀÕÃiÃÊ >ÀiÊ }iniÀ>llÞÊ ÌÀ>nÃmiÌÌi`Ê V>ÌÊ ÌoÊ V>ÌÊ via URT secretions and aerosol transmission over short distances; however, environmental contami- nation can occur, especially in multicat situations. » FHV is susceptible to common disinfectants, antiseptics, and detergents. » FCV, however, can persist in the environment for about a month and is resistant to many com- mon disinfectants; bleach is the preferred agent for killing the virus. UÊ >ÌÃÊ ÜiÌhÊ 1,/Ê Ãi}nÃÊ ÃhoÕl`Ê LiÊ iÃol>Ìi`Ê `ÕÀin}Ê their hospital stay in an area with adequate venti- lation. Strict hygiene practices should be followed, including bleaching of cages and other items in contact with infected cats. H1N1 Influenza Virus H1N1 influenza virus (swine flu) has been identified in cats, receiving some interest given its significance in human medicine. Naturally occurring H1N1 infection was first docu- mented in cats in 2009 and was associated with the human pandemic.7-9 Cats most likely acquired the virus from their human household companions.10 Thus, the virus is essen- tially absent from surveyed feral cat populations.11 H1N1 infection appears to occasionally result in signs of acute upper and lower respiratory tract disease in V>ÌÃ°Ê oÀÌ>liÌÞÊiÃÊ>ÌÌÀiLÕÌ>LliÊÌoÊÃiÛiÀiÊ«niÕmoni>° Bacterial Infection "ÌhiÀÊ«Àim>ÀÞÊ1,/Ê«>Ìho}inÃÊinVlÕ`i\1,3,12 UÊChlamydia psittaci UÊMycoplasma felis UÊM gatae UÊBordetella bronchiseptica. Although these can be primary bacterial pathogens, they are more commonly secondary to and concurrent with viral infection. Notably, viral agents damage the respi- ratory epithelium, especially in young cats, making the cat more susceptible to opportunistic pathogens, such as staphylococci, streptococci, pasteurellae, and coliforms. Fungal Infection Fungal infections (eg, nasal cryptococcosis) can also occur. OTHER CAUSES Nasopharyngeal Polyps Nasopharyngeal polyps can cause chronic URT signs. UÊ/hiÃiÊ «olÞ«ÃÊ oÀi}in>ÌiÊ inÊ ÌhiÊ ÕÃÌ>Vhi>nÊ ÌÕLiÊ or middle ear and are a source of upper airway obstruction.13 UÊ7hiliÊn>Ão«h>ÀÞn}i>lÊ«olÞ«ÃÊ>ÀiÊinvl>mm>ÌoÀÞÊinÊ nature, their exact etiology is not known. UÊ*olÞ«ÃÊ >ÀiÊ }iniÀ>llÞÊ voÕn`Ê inÊ ÞoÕn}Ê V>Ìð14 They are a rare cause of URT signs in older cats; in this age group, neoplastic processes predominate.15 Figure 1. Bilateral, moderate serous ocular dis- charge and marked, mucopurulent nasal dis- charge in a cat with feline URT disease. Figure 2. Bilateral, serosanguineous ocular dis- charge, blepharospasm, and nasal discharge in a 4-year-old, neutered male cat with recrudes- cence of FHV-1 and associated superficial ulcer- ation and keratoconjunctivitis in both eyes. July/August 2012 Today's Veterinary Practice 15