Showing posts with label feline herpesvirus. Show all posts

Monday, May 6, 2013

New approaches to treating feline herpesvirus eye infections

Progress report on Winn grants MT10-007, MT11-007

Wilkes RP, Ward DA, Newkirk KM, Adams JK and Kania SA. Evaluation of delivery agents used for introduction of small interfering RNAs into feline corneal cells. Am J Vet Res. 2013; 74: 243-7.

Feline herpesvirus (FHV-1) is a cause of chronic recurrent infections that can cause severe eye disease. This research, funded by Winn Feline Foundation since 2010, examined several agents for usefulness as carriers for administration of a potential new antiviral agent, small interfering RNAs (siRNAs). siRNAs use the cell’s own machinery to inhibit viral replication through interfering with the function of essential FHV-1 genes. These investigators have proven that this approach works to inhibit FHV-1. The next step was to test various delivery agents for use in topical administration to the eyes, the site of chronic FHV-1 infection.

Three of the delivery agents tested were effective at facilitating cellular transfer of the siRNA and viral replication was inhibited. The agents were nontoxic and nonirritating. Unfortunately, none of the agents were effective at delivering the siRNA to the cells of the feline cornea. Winn has funded the next phase of this project as the search continues for another approach such as a nanoparticle delivery vehicle. [MK]

See also: Wilkes RP and Kania SA. Evaluation of the effects of small interfering RNAs on in vitro replication of feline herpesvirus-1. Am J Vet Res. 2010; 71: 655-63.

Related blog posts:
Treatment of feline ocular herpesvirus infection (June 2012)
New treatment for feline herpesvirus (Sept. 2009)

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Diagnosis of feline conjunctivitis

Hillström A, Tvedten H, Källberg M, Hanås S, Lindhe A and Holst BS. Evaluation of cytologic findings in feline conjunctivitis. Vet Clin Pathol. 2012; 41: 283-90.

Conjunctivitis is a common problem in cats. The most common causes of conjunctivitis are infections. Feline herpesvirus (FHV-1), Chlamydophila felis (C. felis), and Mycoplasma felis (M. felis) are the most common infectious agents present. PCR analysis has the highest sensitivity along with high specificity and is usually the preferred method for diagnosis. The objectives of this study were to describe the cytological findings in cats with conjunctivitis and compare the findings with the results of PCR analysis for these three main infectious agents. Conjunctival smears from 88 cats with conjunctivitis and 10 healthy control cats were evaluated.

Infectious agents identified by PCR analysis were FHV-1 in 9 cats, C. felis in 8 cats, and M. felis in 6 cats. All 8 cats that were positive for C. felis by PCR testing had epithelial inclusions interpreted as chlamydial inclusions on conjunctival smears. PCR analysis also detects potential co-infection of C. felis with M. felis and FHV-1. The cytological examination of samples from cats with and without M. felis infections resulted in both false positive and negative diagnoses. Therefore, cytological examination was not a highly specific or sensitive diagnostic test for M. felis infection. Many inflammatory cells were present in conjunctival smears from all cats infected with C. felis. This would support the finding that the absence of inflammation makes the diagnosis of C. felis infection unlikely. When many typical inclusions of C. felis are found, cytological examination can be diagnostic, but not when inclusions are considered “suspicious”. Finding eosinophils in conjunctival smears may be an indication to perform PCR testing for FHV-1. Viral inclusions of FHV-1 were not found in specimens stained with Romanowsky stains. Researchers found the effectiveness of cytologic diagnosis is greatly affected by the quality of the smears. [VT]

See also: Gould D. Feline herpesvirus-1: ocular manifestations, diagnosis and treatment options. J Feline Med Surg. 2011; 13: 333-46.

Related blog articles:
Treatment of feline herpesvirus (Feb 2009)
Pradofloxacin for feline upper respiratory tract disease (March 2008)

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Infectious diseases in cat shelters

DiGangi BA, Levy JK, Griffin B, et al. Prevalence of serum antibody titers against feline panleukopenia virus, feline herpesvirus 1, and feline calicivirus in cats entering a Florida animal shelter. J Am Vet Med Assoc. 2012; 241: 1320-5.

Feline panleukopenia virus (FPV), feline herpes virus 1 (FHV-1), and feline calicivirus (FCV) are widespread in the cat population, and particularly in shelter environments. The American Association of Feline Practitioners guidelines recommend that all cats at or over 4 weeks of age be vaccinated against these three viruses upon admission to animal shelters. However, the proportion of cats entering shelters that are already protected (i.e., seropositive) against infection (FPV) or disease (FHV-1 and FCV) because of prior vaccination or natural exposure is usually unknown. The objective of this study was to determine the prevalence of and factors associated with seropositivity for FPV, FHV-1, and FCV in cats entering a Florida animal shelter.

Of 347 cats enrolled in this study, prevalence of seropositivity was 39.8%, 11.0% and 36.6% against FPV, FHV-1, and FCV, respectively. Factors associated with seropositivity included sterilization, age equal to or greater than 6 months, and relinquishment by an owner. Surprisingly, community origin (i.e., rural or urban), health status, signs of previous caregiving aside from sterilization, and outcome (i.e., adopted, transferred, euthanized, or reclaimed by owner) were not associated with seropositivity and should not be used to determine an individual cat’s need for vaccination. This study suggests that most cats admitted to an animal shelter do not have adequate antibody protection against infection or disease; therefore, the recommendation to vaccinate all cats admitted to an animal shelter is reasonable and vaccination should not be withheld due to signs of previous veterinary care. [GO]

See also: DiGangi BA, Gray LK, Levy JK, Dubovi EJ and Tucker SJ. Detection of protective antibody titers against feline panleukopenia virus, feline herpesvirus-1, and feline calicivirus in shelter cats using a point-of-care ELISA. J Feline Med Surg. 2011; 13: 912-8.

Related blog articles:
Upper respiratory tract disease in shelters (November 2009)
Disease control in animal shelters (May 2011)
Coronavirus in California shelter cats (April 2012)

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Treatment of feline ocular herpesvirus infection

Each year, the Winn Feline Foundation receives proposals from veterinary researchers around the world who are interested in improving feline health. To date, Winn’s cumulative total in feline health research funding exceeds $4 million. Forty-four proposals were submitted by researchers seeking funding in this review cycle. This year, our team of veterinary consultants helped Winn select 10 projects for funding, for a total of $174,018. Here is one of those projects:

W12-042
Development and in vitro optimization of hydrogels for the delivery of FHV specific siRNAs encapsulated in chitosan nanoparticles
Investigators: Rebecca Wilkes, Scott Lenaghan, Christopher Stephens; University of Tennessee

Feline herpesvirus-1 (FHV-1) typically causes respiratory disease in cats. However, chronic infections can cause severe eye disease that may lead to blindness. Currently there is no effective treatment for these chronic cases. Previous Winn funding has helped the investigators design a therapeutic agent – small interfering RNAs (siRNAs) – which use the cell’s own machinery to inhibit viral replication through the targeting of essential herpesvirus genes. The investigators have developed a nanoparticle delivery vehicle composed of chitosan, a nontoxic substance, to package these siRNAs for delivery into cells. The goal of this study is to develop a hydrogel, similar to a soft contact lens, for delivery of the nanoparticles. The hydrogel can be placed directly into the cat’s eye, allowing for successful drug uptake. This method will also provide extended continuous delivery of the FHV-1 specific siRNAs into the cells of the cornea. This study will potentially lead to development of a product suitable for use in cats’ eyes for the treatment of FHV-1 infections.

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Feline facial dermatitis & herpesvirus

Persico P, Roccabianca P, Corona A, Vercelli A and Cornegliani L. Detection of feline herpes virus 1 via polymerase chain reaction and immunohistochemistry in cats with ulcerative facial dermatitis, eosinophilic granuloma complex reaction patterns and mosquito bite hypersensitivity. Vet Dermatol. 2011; 22: 521-7.

Ulcerative dermatitis secondary to feline herpesvirus (FHV) infection is an uncommon disease that may resemble other cutaneous diseases such as eosinophilic granuloma and mosquito bite hypersensitivity. The investigators compared two methods for diagnosis of FHV-associated dermatitis – polymerase chain reaction (PCR) for amplification and detection of viral genetic material and immunohistochemistry (IHC) for detection of viral protein. Skin biopsy specimens from 62 cats with ulcerative skin lesions were tested by both methods. Immunohistochemistry for viral protein is considered the gold standard for diagnosis. PCR detected the presence of FHV genetic material in 12 samples, while IHC was positive in only two. Because of its high sensitivity and ability to detect latent or vaccinal virus, the authors concluded that PCR alone could result in misdiagnosis of FHV-associated dermatitis. They recommend PCR as an initial screening test, and, if positive, confirmation testing should be performed using IHC. [MK]

Related articles: Lee M, Bosward KL and Norris JM. Immunohistological evaluation of feline herpesvirus-1 infection in feline eosinophilic dermatoses or stomatitis. J Feline Med Surg. 2010; 12: 72-9.

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Cats and Viruses

Hellard E, Fouchet D, Santin-Janin H et al: When cats' ways of life interact with their viruses: a study in 15 natural populations of owned and unowned cats (Felis silvestris catus), Preventive Veterinary Medicine 101:250, 2011.

Cats are susceptible to a number of important viruses that can cause significant disease. The living conditions and behavior of various cat populations will affect their susceptibility and risk of exposure to these viruses. The investigators examined 15 populations of non-sterilized unvaccinated cats living in the same area of France. These populations had one of two different lifestyles – owned (sheltered and fed, socialized) and unowned (no shelter or food provided, unsocialized). Blood samples were tested for exposure of the cats to feline herpesvirus (FHV), calicivirus (FCV), parvovirus (FPV), immunodeficiency virus (FIV), and leukemia virus (FeLV). Not surprisingly, the unowned cats were more likely to have been infected with FHV, FCV, and FIV – these viruses largely require direct contact between cats, including fighting. The owned cats were more likely to have been infected with FPV. For each virus, the likelihood of having been infected varied with the population. For example, FIV infection was more likely in older, male, unowned cats; FHV was more likely to infect kittens at an earlier age in unowned versus owned populations; FPV infection was more likely in owned populations perhaps because of shared environments in human settlements. The main crux of this paper was that the epidemiology of a particular virus within cat populations can be affected by their behavior and lifestyle. Failure to consider these aspects can skew results of epidemiologic analyses. For example, when the status of the owned and unowned cats were combined, a different epidemiologic picture was seen for the various viruses examined – the risk factors were different, and included such factors as body mass. Pooling different types of cats in a single sample without taking behavior and lifestyle into account could give a misleading picture of the epidemiology of their viruses. [MK]

Related articles: Pontier D, Fouchet D, Bahi-Jaber N et al: When domestic cat (Felis silvestris catus) population structures interact with their viruses, C R Biol 332:321, 2009.

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PCR Testing for Feline Respiratory Viruses

Ruch-Gallie RA, Veir JK, Hawley JR et al: Results of molecular diagnostic assays targeting feline herpesvirus-1 and feline calicivirus in adult cats administered modified live vaccines, J Feline Med Surg 13:541, 2011.

Diagnostic testing to identify the cause of a respiratory infection in a cat today often involves molecular testing of swabs collected from the nasal and pharyngeal areas. These assays detect the genetic material of the virus of interest. These molecular assays, known as real-time polymerase chain reaction (RT-PCR), are very sensitive, able to detect very small amounts virus. Vaccines given to cats, including cats entering shelters, are usually live virus vaccines. When respiratory disease occurs in these cats soon after vaccination, the concern is that the molecular assays may detect the vaccine virus, confusing the diagnosis. These researchers investigated the likelihood of detecting virus in the days immediately following vaccination. They tested multiple samples collected from six cats given an intranasal vaccine and six given a subcutaneous vaccine. Overall, the detection of virus within days after vaccination was uncommon. The risk was slightly higher with intranasal vaccines versus the subcutaneous vaccines. But the percentage of samples collected that gave positive results was quite small. Thus, the risk of false positive results from vaccination appears to be low. [MK]

Related articles:
Maggs D, Clarke H: Relative sensitivity of polymerase chain reaction assays used for detection of feline herpesvirus type 1 DNA in clinical samples and commercial vaccines, Am J Vet Res 66:1550, 2005.

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Feline Gingivostomatitis

Dowers KL, Hawley JR, Brewer MM et al: Association of Bartonella species, feline calicivirus, and feline herpesvirus 1 infection with gingivostomatitis in cats, Journal of Feline Medicine & Surgery 12:314, 2010.

Feline gingivostomatitis (FGS) is a common and devastating disease in cats that results in painful erosive lesions in the throat, oral mucosa, tongue, and gingiva. In many situations, there is not a cure and therapy must be intermittent or chronic. Three of the more common differential diagnoses are feline calicivirus (FCV), feline herpesvirus 1 (FHV-1), and Bartonella species. A total of 131 client-owned cats were involved in this study, 70 of which had FGS confirmed by histopathology and 61 healthy control cats. Results of this study did not find an association between Bartonella species test results (Bartonella species antibodies and DNA in the blood and tissues) and the presence of FGS. Additionally, detection of FHV-1 DNA was not significantly different between groups. With FCV, RNA was present in significantly more cats with FGS (40.5%) than the control cats (0%). This would suggest that in some of the cats, FCV was associated with FGS. An association could not be shown however between FCV RNA in tissues and lesion severity or location. [VT]

Related articles:
Quimby JM, Elston T, Hawley J et al: Evaluation of the association of Bartonella species, feline herpesvirus 1, feline calicivirus, feline leukemia virus and feline immunodeficiency virus with chronic feline gingivostomatitis, J Feline Med Surg 10:66, 2008.

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Feline Herpesvirus

Lee M, Bosward KL, Norris JM: Immunohistological evaluation of feline herpesvirus-1 infection in feline eosinophilic dermatoses or stomatitis, J Feline Med Surg 12:72-79, 2010.

Feline herpesvirus (FHV) is well known cause of upper respiratory tract disease. Less commonly, it is also associated with inflammatory oral disease (stomatitis) and dermatitis, primarily on the face. Cats with FHV dermatitis have erythema, swelling, crusting, and ulceration typically around the muzzle and around the eyes. Diagnosis may be difficult as it relies on finding intranuclear viral inclusion bodies on biopsy samples. Many cases are misdiagnosed as eosinophilic granuloma complex (EGC) or another skin disease. This study used immunohistochemistry (IHC) and histopathology to detect the presence of FHV in biopsy samples from cats suspected of having EGC, other eosinophilic skin diseases, and stomatitis. Cases were taken from samples submitted to the University of Sydney between 1996 and 2008. Of the 30 cases examined, two showed a positive reaction for FHV using IHC. In both cases, intranuclear inclusion bodies were found on histopathology, but were difficult to detect. The authors conclude that FHV is uncommonly associated with EGC or similar skin diseases in cats in Sydney, Australia. They also point out that misdiagnosis can easily occur, and FHV should be considered in cats with severe ulcerative skin lesions, especially when unresponsive to corticosteroid treatment. IHC is helpful to differentiate FHV dermatitis from other skin diseases. [SL]

Related articles:
Malik R, Lessels NS, Webb S et al: Treatment of feline herpesvirus-1 associated disease in cats with famciclovir and related drugs, Journal of Feline Medicine & Surgery 11:40-48, 2009.

Holland JL, Outerbridge CA, Affolter VK et al: Detection of feline herpesvirus 1 DNA in skin biopsy specimens from cats with or without dermatitis, J Am Vet Med Assoc 229:1442-46, 2006.

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Lysine for Feline Upper Respiratory Tract Disease

Drazenovich, T. L., A. J. Fascetti, et al. (2009). "Effects of dietary lysine supplementation on upper respiratory and ocular disease and detection of infectious organisms in cats within an animal shelter." Am J Vet Res 70(11): 1391-400.

Feline herpesvirus (FHV) is a common cause of respiratory infections in cats housed in shelter situations. Cats latently infected with feline herpesvirus are important sources of the virus for cats that are susceptible to infection. Medications that interfere with latency establishment or reactivation of latent infections would be extremely useful, especially in rescue facilities, where animals are often highly stressed, and have variable vaccination history and immune status. Lysine has shown promise in mediating antiviral effects in cats. These researchers investigated the usefulness of dietary supplementation with lysine for cats in shelters to decrease incidence of infection and detection of FHV shedding. Using 261 adult cats, basal diets (control group) and diets supplemented with lysine (treated group) were fed for four weeks. Unexpectedly, they found that treated cats were actually more likely to manifest severe disease than untreated controls at certain time points in the study (week 4). In addition, FHV was detected more commonly in treated cats (found in week 2 only). A confounding factor was that cats in both groups were also allowed access to commercial diets when hospitalized for illness in addition to the control and test diets. The researchers concluded that continuous dietary supplementation with lysine did not successfully control respiratory disease in a shelter situation, and is not an optimal use of funds in rescue facilities. Bolus treatment of cats with lysine may provide better plasma lysine levels than continuous dietary supplementation, and may provide more beneficial effects.
>> PubMed Abstract

Related articles:
Maggs, D. J., J. E. Sykes, et al. (2007). "Effects of dietary lysine supplementation in cats with enzootic upper respiratory disease." J Feline Med Surg 9(2): 97-108.
>> PubMed Abstract

Rees, T. M. and J. L. Lubinski (2008). "Oral supplementation with L-lysine did not prevent upper respiratory infection in a shelter population of cats." J Feline Med Surg 10(5): 510-3.
>> PubMed Abstract

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Latent Feline Herpesvirus Infection

Richter M, Schudel L, Tobler K et al: Clinical, virological, and immunological parameters associated with superinfection of latently with FeHV-1 infected cats, Vet Microbiol 138:205, 2009.

Feline herpesvirus (FHV) is a common respiratory and ocular pathogen of cats. It may be associated with recurrent ocular disease, even in vaccinated cats. These investigators examined the role of superinfecting FHV strains in recurrent disease. To do this, they genetically engineered a FHV strain to fluoresce, so that it could be distinguished from wild type strains of the virus. It was used to superinfect nine cats that were latently infected with a wild type strain of FHV. Active infection of the mutant virus in the inoculated cats was documented, but reactivation of the latent wild type strain did not occur. Following infection, no change in the clinical condition of the cats occurred. A rise in antibody titer and increased interferon production were noted. Thus, superinfection did induce an immune response, but was not associated with reactivation of latent virus. The authors concluded that vaccination of latently infected cats does not lead to reactivation of the latent virus, nor clinical disease. Sixteen months after superinfection, the cats were temporarily immunosuppressed, and assessed for reactivation of FHV. Mild signs were observed in all cats. Interestingly, only the wild type virus was identified; there was no evidence of mutant virus reactivation. Thus, it was not clear that the mutant virus was able to establish latency. The clinical disease observed was due to the reactivation of the latent wild type strain. The researchers continue to investigate the usefulness of this mutant marker virus to establish the pathogenesis of recurrent FHV disease. [MK]
>> PubMed Abstract

Related articles:
Weigler BJ, Babineau CA, Sherry B et al: High sensitivity polymerase chain reaction assay for active and latent feline herpesvirus-1 infections in domestic cats, Vet Rec 140:335, 1997.
>> PubMed Abstract

Thiry E, Addie D, Belak S et al: Feline herpesvirus infection. ABCD guidelines on prevention and management, J Feline Med Surg 11:547, 2009.
>> PubMed Abstract

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Upper Respiratory Tract Disease in Shelters

Dinnage, J.D., J.M. Scarlett, and J.R. Richards, Descriptive epidemiology of feline upper respiratory tract disease in an animal shelter. J Feline Med Surg, 2009. 11(10): p. 816-25.

Upper respiratory tract disease (URTD) is a common disease in cats and can spread quickly among cats residing in animal shelters. These infections cause suffering, consume vital personnel and financial resources, and limit adoptions. In a large urban shelter in the northeast United States, 531 kittens, 701 litters, and 2,203 adult cats were observed during their stays on a daily basis over a period of 50 weeks for signs of URTD. The median lengths of stay for adult cats and kittens were 5 and 4 days, respectively. Approximately 1/3 of the cats exhibited signs of infectious respiratory disease. Regardless of age group, the probability of developing URTD rose steadily with increasing time spent in the shelter. The probability of exhibiting signs remained low until day 6 and then rose steadily to where by day 14, the cumulative probabilities had risen to 84% (litters), 86% (individual kittens), and 80% (adult cats). In different categories, adult cats over 11 years of age had a significantly higher risk of URTD than younger cats. Neutered males cats had higher rates of URTD than spayed females, and purebred cats were at higher risk than ones of mixed breeding. Strays were more likely to have URTD than owner-surrendered cats. The study documented the strong association between the length of the residence in a shelter and the risk of developing URTD. The results suggest shelters should focus efforts and programs at minimizing the length of time cats spend in a shelter. [VT]
>> PubMed Abstract

Related articles:
Zicola, A., et al., Feline herpesvirus 1 and feline calicivirus infections in a heterogeneous cat population of a rescue shelter. J Feline Med Surg, 2009.
>> PubMed Abstract

Edwards, D.S., et al., Risk factors for time to diagnosis of feline upper respiratory tract disease in UK animal adoption shelters. Prev Vet Med, 2008. 87(3-4): p. 327-39.
>> PubMed Abstract

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Probiotic Supplementation in Cats

Lappin MR, Veir JK, Satyaraj E et al: Pilot study to evaluate the effect of oral supplementation of Enterococcus faecium SF68 on cats with latent feline herpesvirus 1, J Feline Med Surg 11:650, 2009.

A very common infectious disease in cats is feline herpesvirus-1 (FHV-1). The virus is frequently associated with morbidity because of recurrent ocular and respiratory signs of disease. One dietary supplemental probiotic, Enterococcus faecium strain SF68, has immune enhancing properties. SF68 supplementation is considered safe for use in cats. Twelve cats with chronic FHV-1 infections were given either SF68 or a placebo. The cats were then monitored for clinical signs of disease, monitored for FHV-1 shedding, and evaluated for FHV-1 specific humoral and cell-mediated responses and fecal microbiome stability. The researchers found that clinical results varied amongs individual cats, although overall findings suggested that administration of the probiotic lessened morbidity associated with chronic FHV-1 infection in some cats. This was a pilot study and additional research is warranted to evaluate this protocol in a clinical setting. [VT]
>> PubMed Abstract

Related articles:
Veir JK, Knorr R, Cavadini C et al: Effect of supplementation with Enterococcus faecium (SF68) on immune functions in cats, Vet Ther 8:229, 2007.
>> PubMed Abstract

Veir JK, Lappin MR, Dow SW: Evaluation of a novel immunotherapy for treatment of chronic rhinitis in cats, J Feline Med Surg 8:400, 2006.
>> PubMed Abstract

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New Treatment for Feline Herpesvirus

Winn funded research

Wilkes RP, Kania SA. Use of interfering RNAs targeted against feline herpesvirus 1 glycoprotein D for inhibition of feline herpesvirus 1 infection of feline kidney cells. Am J Vet Res 2009; 70: 1018-25.

Feline herpesvirus causes at least 50% of upper respiratory infections in the cat. While vaccines are available, the virus persists in cat populations and spreads readily from infected to naive cats. As well, chronic disease occurs in latently infected cats. Most antiviral medications approved for a similar virus in people are either too toxic for cats or are only minimally effective. Small interfering RNAs (RNAi) are novel therapies that can be used to inhibit expression of genes of interest. This study evaluated the use of RNAi targeted against feline herpesvirus glycoprotein D in order to inhibit herpesvirus infection of cell cultures. Six chemically produced RNAi constructs were evaluated, and two of them proved highly effective in reducing expression of the target glycoprotein. Treatment of cell cultures with RNAi resulted in inhibition of herpesvirus replication. The researchers were able to show that glycoprotein D is essential for the virus to infect cells, and is a potential new target for antiviral treatment. [SL]
>> PubMed Abstract

Related articles:
Thiry E, Addie D, Belak S, et al. Feline herpesvirus infection. ABCD guidelines on prevention and management. J Feline Med Surg 2009; 11: 547-55.
>> Free, full text article

Malik R, Lessels NS, Webb S, et al. Treatment of feline herpesvirus-1 associated disease in cats with famciclovir and related drugs. Journal of Feline Medicine & Surgery 2009; 11: 40-48.
>> PubMed Abstract

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Herpesvirus Infections in Cats

Westermeyer, H. D., S. M. Thomasy, et al. (2009). "Assessment of viremia associated with experimental primary feline herpesvirus infection or presumed herpetic recrudescence in cats." American Journal of Veterinary Research 70(1): 99-104.

Feline herpesvirus-1 is associated with respiratory disease, often in kittens. Most infected cats remain latently infected for life; these latent infections may reactivate during times of stress. While herpesviruses in other species commonly spread to other tissues in infected animals via the bloodstream, this appears to be infrequent in cats. These researchers investigated the occurrence of virus in the blood of infected cats during acute infection, as well as during reactivation of latent infections. Following infection of six cats with FHV-1, virus was detected in the blood for up to two weeks post-infection. However, virus was not detected in the blood of 34 shelter cats, 25 of whom had evidence of FHV-associated disease and tested positive for the virus on conjunctival samples, using either virus isolation or polymerase chain reaction (PCR) testing. The authors conclude there may be a brief period of viremia in cats following acute infection, but none associated with reactivation of latent infection. [MK]
>> PubMed Abstract

Related articles:
Maggs, D., M. Lappin, et al. (1999). "Evaluation of serologic and viral detection methods for diagnosing feline herpesvirus-1 infection in cats with acute respiratory tract or chronic ocular disease." J Amer Vet Med Assoc 214(4): 502.
>> PubMed Abstract

Bannasch, M. and J. Foley (2005). "Epidemiologic evaluation of multiple respiratory pathogens in cats in animal shelters." J Fel Med Surg 7(2): 109-119.
>> PubMed Abstract

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Feline Eosinophilic Keratitis

Spiess, A. K., J. S. Sapienza, et al. (2009). "Treatment of proliferative feline eosinophilic keratitis with topical 1.5% cyclosporine: 35 cases." Vet Ophthalmol 12(2): 132-7.

Eosinophilic keratitis is a progressive corneal disease seen in cats of any age. While the etiology is unknown, an immune-mediated response to feline herpesvirus is a suspected cause. The disease is unilateral in up to 75% of cases. The lesions are typically raised, irregular, white to pink masses. Scrapings of the lesions contain eosinophils, mast cells, and mixed inflammatory cells. Treatment is with topical corticosteroids, although some cases become refractory. Relapse is common if treatment is discontinued. The purpose of this study was to evaluate the efficacy of topical cyclosporine for feline eosinophilic keratitis. The disease was diagnosed by clinical appearance and corneal cytology in 35 cats. The mean age of affected cats was 6 years. Topical cyclosporine was administered either two or three times daily. The minimum follow up period was 5 months. Improvement was seen in 89% of cats. Recurrence was seen in 23% of cases. The researchers conclude that topical cyclosporine is an effective treatment for the majority of cats with eosinophilic keratitis, and that chronic, often life-long therapy is recommended. [SL]
>> PubMed Abstract

Related articles:
Andrew, S. E. (2008). "Immune-mediated canine and feline keratitis." The Veterinary clinics of North America. Small animal practice 38(2): 269-290.
>> PubMed Abstract

Moore, P. A. (2005). "Feline corneal disease." Clin Tech Small Anim Pract 20(2): 83-93.
>> PubMed Abstract

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Response to Vaccinations in Cats

Lappin, M. R., J. Veir, et al. (2009). "Feline panleukopenia virus, feline herpesvirus-1, and feline calicivirus antibody responses in seronegative specific pathogen-free cats after a single administration of two different modified live FVRCP vaccines." Journal of Feline Medicine & Surgery 11(2): 159-162.

Researchers at Colorado State University evaluated the antibody response of cats to a single inoculation of one of two modified live vaccines containing feline panleukopenia virus (FPV), feline herpesvirus (FHV) and feline calicivirus (FCV). These pathogens commonly infect cats, and some cats at greatest risk, such as those in shelters or pet stores, may suffer severe disease, or even death. In these situations, rapid onset of immunity following vaccination is needed. The investigators sought to determine the timing of seroconversion in 10 seronegative cats following a single vaccination with either an intranasal vaccine or one given subcutaneously (both are commercially available vaccines). This study had limitations, in that the number of cats tested were small, and protection was evaluated by antibody levels only. In addition, the cats tested were adults not kittens; thus, the ability to break through maternal immunity could not be evaluated. Nevertheless, results were informative. While all cats developed detectable FPV and FCV antibody titers; only two cats developed detectable FHV-1 antibody titers indicating two vaccinations are required for adequate protection. For FPV and FHV-1, there were no differences in seroconversion rates between the cats that were given the intranasal versus the injectable vaccine. However, for FCV, the cats that were administered the IN FVRCP vaccine were more likely to seroconvert earlier than cats that were administered the injectable vaccine. These results suggest that the FVRCP vaccine administered IN should be considered in populations of FCV naive cats with high risk of exposure. [MK]
>> PubMed Abstract

Related articles:
Lappin, M. R., R. W. Sebring, et al. (2006). "Effects of a single dose of an intranasal feline herpesvirus 1, calicivirus, and panleukopenia vaccine on clinical signs and virus shedding after challenge with virulent feline herpesvirus 1." J Feline Med Surg 8(3): 158-63.
>> PubMed Abstract

Lappin, M. R., J. Andrews, et al. (2002). "Use of serologic tests to predict resistance to feline herpesvirus 1, feline calicivirus, and feline parvovirus infection in cats." J Am Vet Med Assoc 220(1): 38-42.
>> PubMed Abstract

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Treatment of Feline Herpesvirus

Malik R, Lessels NS, Webb S, et al. Treatment of feline herpesvirus-1 associated disease in cats with famciclovir and related drugs. Journal of Feline Medicine & Surgery. 2009;11(1):40-48.

Herpesvirus is the most common cause of ocular and upper respiratory disease in the cat, but is also associated with other clinical presentations such as dermatitis and pneumonia. Systemic antiviral treatment for feline herpesvirus has been problematic. First generation nucleoside analogues such as acyclovir have little clinical efficacy and significant adverse effects in cats. Famciclovir (Famvir, Novartis) is a newer drug that is often used by veterinary ophthalmologist and appears to be well tolerated by cats. This article details oral famciclovir treatment of 10 cats with presumptive herpesvirus infection as a cause of ocular disease, rhinosinusitis, and dermatitis. Famciclovir doses ranged from 62.5 mg/cat once or twice daily, up to 125 mg/cat three times daily. In all cases, the drug was well tolerated and caused clinical improvement. These and other reports support the use of famciclovir as anti-herpesvirus therapy in cats. Further research should be conducted to determine the optimal dose, dosing interval, and duration of treatment.
>> PubMed Abstract

Related articles:
Thomasy SM, Maggs DJ, Moulin NK, Stanley SD. Pharmacokinetics and safety of penciclovir following oral administration of famciclovir to cats. Am J Vet Res. Nov 2007;68(11):1252-1258.
>> PubMed Abstract

More on cat health: Winn Feline Foundation Library

Causes of Gingivitis in Cats

Quimby, J. M., T. Elston, et al. (2008). "Evaluation of the association of Bartonella species, feline herpesvirus 1, feline calicivirus, feline leukemia virus and feline immunodeficiency virus with chronic feline gingivostomatitis." J Feline Med Surg 10(1): 66-72.

Gingivostomatitis is a common medical condition in cats. Clinical signs include red and swollen gums that may bleed easily, halitosis, and oral pain. The discomfort can lead to dysphagia, decreased appetite, and weight loss. The syndrome is likely to be multifactorial and it is suspected to involve an exaggerated immune response to either infectious or non-infectious antigens. Other factors that may be involved include genetic predispostion, diet, stressors, and the effects of domestication. Several infectious agents have been found in cats with gingivostomatitis such as feline leukemia virus (FeLV), feline immunodeficiency virus (FIV), calicivirus (FCV), herpesvirus (FHV-1), and Bartonella. However, all these agents can also be found in healthy cats so proving cause and effect has been difficult. The 45 cats in this study were housed together, had a history of flea exposure, and were vaccinated with a modified live FVRCP vaccine. At the time of sample collection, 36 of the cats had active gingivostomatitis. Samples were collected and analyzed for infectious agents. All of the agents were found in the population with the exception of FeLV. However, evidence of infection with Bartonella species, FHV-1, FCV, FeLV or FIV was not overrepresented in the cats with gingivostomatitis and so the data fail to support the hypotheses that these organisms were a cause of gingivostomatitis in this population of cats. The researchers conclude that diagnostic test results for these infectious agents should be interpreted carefully as none appear to correlate to the presence or absence of disease.
>> PubMed abstract

Related articles:
Southerden, P. and C. Gorrel (2007). "Treatment of a case of refractory feline chronic gingivostomatitis with feline recombinant interferon omega." J Small Anim Pract 48(2): 104-6.
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More on cat health: Winn Feline Foundation Library

Treatment of Feline Herpesvirus with Cidofovir

Fontenelle, J. P., C. C. Powell, et al. (2008). "Effect of topical ophthalmic application of cidofovir on experimentally induced primary ocular feline herpesvirus-1 infection in cats." Am J Vet Res 69(2): 289-93.

The efficacy of twice-daily topical application of 0.5% cidofovir in cats with experimentally induced ocular feline herpesvirus-1 (FHV-1) infection was evaluated in this project. Twelve cats were infected with an FHV-1 field strain and divided into treatment and control groups. The treatment group received 1 drop of cidofovir solution in both eyes twice daily for 2 weeks, starting on day 4. The control group received 1 drop of the same solution but without cidofovir. The cats were evaluated with a standard scoring system for 24 days. Ocular viral shedding was assessed with PCR every 3 days. During the treatment period, the clinical scores and amount of viral shedding were significantly lower in the treatment group compared to the control group. No systemic or local adverse effects were seen in the cats treated with cidofovir, and all cats were monitored for at least 1 year following the end of the project. Cidofovir may represent an effective new treatment for FHV-1 with the added benefits of causing less local irritation than currently available topical treatments, and requiring less frequent administration.
>> PubMed abstract

For further reading:
van der Meulen, K., B. Garre, et al. (2006). "In vitro comparison of antiviral drugs against feline herpesvirus 1." BMC Vet Res 2: 13.
>> Free full text article

Sandmeyer, L. S., C. B. Keller, et al. (2005). "Effects of cidofovir on cell death and replication of feline herpesvirus-1 in cultured feline corneal epithelial cells." Am J Vet Res 66(2): 217-22.
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More on cat health: Winn Feline Foundation Library

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