Aetiology of corneal ulcers assume FHV-1 unless proven otherwise

Evaluation of compounded cidofovir, famciclovir, and ganciclovir for the treatment of feline herpesvirus ocular surface disease in shelter-housed cats

OBJECTIVE

To assess the efficacy of compounded cidofovir, famciclovir, and ganciclovir for the treatment of feline herpesvirus type 1 (FHV-1) ocular surface disease.

ANIMALS STUDIED

132 shelter-housed cats qPCR positive for FHV-1.

PROCEDURES

A masked placebo-controlled study design was utilized. Animals were enrolled in one of four treatment groups: topical ocular placebo + oral placebo (n = 32), compounded cidofovir 0.5% ophthalmic solution + oral placebo (n = 32), compounded famciclovir oral solution (90 mg/kg) + topical ocular placebo (n = 32), and compounded ganciclovir 0.15% ophthalmic solution + oral placebo (n = 36). Cats were treated with each medication twice daily for 7 days and were evaluated on Day 1 and Day 8 using an ocular scoring system, body weight, and qPCR for FHV-1 viral load.

RESULTS

Cidofovir significantly decreased viral load from Day 1 to Day 8 compared with placebo (p = .024). Neither famciclovir nor ganciclovir decreased viral load compared with placebo (p = .14, p = .41). There was no significant improvement of ocular scores for any drug group compared with placebo (p = .62). In all groups, 65%-75% of cats improved from Day 1 to Day 8. Juvenile cats had a significant increase in weight gain compared with placebo for cidofovir (p = .025) and ganciclovir (p = .023). All corneal ulcers in placebo animals failed to heal whereas 77% of ulcers in antiviral group animals healed.

CONCLUSIONS

Topical ophthalmic cidofovir significantly decreased ocular FHV-1 viral shedding and increased weight gain in juvenile cats. Ganciclovir increased weight gain in juvenile cats. Compounded famciclovir demonstrated limited efficacy for the treatment of FHV-1 ocular surface disease in shelter-housed cats.

In vitro efficacy of ganciclovir against feline herpesvirus type 1 and assessment of ocular tolerability in healthy cats

OBJECTIVES

Feline herpesvirus-1 (FHV-1) is a prevalent cause of ocular disease in cats and limited topical options for treatment currently exist. The first objective of this study was to confirm the efficacy of ganciclovir against FHV-1 in vitro. The second objective was to assess the safety and ocular tolerability of topically applied ganciclovir eye gel (GEG) in healthy cats.

METHODS

FHV-1 was used to infect tissue culture wells covered in maximally confluent Crandall-Rees feline kidney cells prior to the addition of three molarities of ganciclovir (8.9 µM, 17.8 µM and 89 µM) before being incubated for 48 h. Ganciclovir efficacy in vitro was then assessed using standard plaque reduction assay. Commercially available GEG (0.15%) was applied q8h to one randomly chosen eye of four healthy cats for 7 days. Commercially available lubricating eye gel (LEG) was applied to the opposite eye q8h. Complete blood counts (CBCs), blood chemistry panels (CHEM) and urinalysis (UA) were performed on all cats before and after the study period. Ocular lesions were assessed daily using a standardized scheme.

RESULTS

Ganciclovir led to a significant reduction in FHV-1 plaque number, area and diameter at all tested molarities in vitro. The highest molarity assessed (89 µM) caused a 100% reduction in viral plaque number. There was no significant difference in ocular lesion scores between eyes receiving GEG and LEG. Animals remained healthy throughout the study period with CBC, CHEM and UA showing no clinically significant alterations.

CONCLUSIONS AND RELEVANCE

Based on the in vitro results, ganciclovir appears to be effective against FHV-1 in vitro. When applied q8h as a commercial 0.15% gel to a small group of cats with normal eyes, this medication was well tolerated. Taken together, these data suggest this medication warrants further investigation in cats with ocular disease caused by FHV-1.

Corneal Ulcer in Dogs and Cats: Novel Clinical Application of Regenerative Therapy Using Subconjunctival Injection of Autologous Platelet-Rich Plasma

Background: Corneal ulcer could be a major source of distress in small animals, with many contributing agents. In recent years, few studies evaluated the efficacy of platelet-rich plasma (PRP) in healing corneal ulcers. Aim: This study aimed to assess the ability of subconjunctival injection of autologous PRP in the treatment of corneal ulcers in dogs and cats as well as estimate the expression of matrix metalloproteinase (MMP)-2, MMP-9, and oxidative stress biomarkers in these patients. Methods: A total number of 28 animals (16 cats and 12 dogs) were enrolled in this study. Each animal was subjected to clinical, neurologic, and ophthalmic examinations where the type of ulcer was documented. Tear samples were collected for evaluation of oxidative biomarkers and MMPs; conjunctival swabs were taken to identify the involved organism. PRP was prepared from each animal and given as subconjunctival injection; numbers of injections were done according to case response. Clinical follow-up was done and documented for each case. Results: In cat patients, female and Persian cats were most affected; unilateral and superficial ulcers were most recorded. In male dogs, unilateral, and superficial ulcers were most recorded. FHV-1 was most identified in cats, while Staphylococcus aureus was most identified in dogs. Numbers of injections needed to achieve healing were recorded, with 50% of dogs needing two injections with 1-week intervals and 50% of cats needed three injections with 1-week intervals. Alterations in both oxidative biomarkers and MMPs were recorded in affected animals. Conclusion: The use of autologous PRP as a subconjunctival injection in treating corneal ulcers in dogs and cats is effective. The number of injections is the case and corneal ulcer type-dependent. Clinical Significance: Autologous PRP as a subconjunctival injection in treating corneal ulcer is a relatively cheap, safe method and can be done in the clinical setting.

Persian cats under first opinion veterinary care in the UK: demography, mortality and disorders

Persian cats are a popular cat breed worldwide, and especially in the US, Europe and Asia. This study aimed to describe the demography, common disorders and mortality in Persians under general practice veterinary care in 2013 in the UK. The study population of 285,547 cats overall included 3235 (1.1%) Persians. Mean adult Persian bodyweight was 3.9 kg (SD 0.9) and median age was 7.0 years (IQR 3.3–11.6). At least one disorder was recorded in 2099 (64.9%) Persians. The most common specific disorders were haircoat disorders (411, 12.7%), periodontal disease (365, 11.3%), overgrown nails (234, 7.2%), and ocular discharge (188, 5.8%). The most common disorder groups were dermatological (578, 17.9%), ophthalmological (496, 15.3%) and dental (397, 12.3%). Median longevity was 13.5 years (IQR 9.9–16.0). The most common grouped causes of death were renal disease (102, 23.4%), neoplasia (37, 8.5%) and mass-associated disorder (35, 8.0%). This is the first study to use general practice data to examine the overall health of Persian cats. With haircoat, ocular and dental disorders being the predominant disorders identified, this study highlights the need for increased owner awareness to manage and prevent the typical health problems associated with this breed’s phenotype.

Cat flu: Broad spectrum polymeric antivirals

Feline herpesvirus type 1 (FHV-1) and feline calicivirus (FCV) are considered as main causes of feline upper respiratory tract disease and the most common clinical manifestations include rhinotracheitis, conjunctivitis, and nasal/facial ulcerations. While the primary infection is relatively mild, secondary infections pose a threat to young or immunocompromised cats and may result in a fatal outcome. In this study, we made an effort to evaluate antiviral potency of poly(sodium 4-styrenesulfonates) (PSSNa) as potent FHV-1 and FCV inhibitors for topical use. Mechanistic studies showed that PSSNa exhibits a different mechanism of action depending on target species. While PSSNa acts directly on FHV-1 particles blocking their interaction with the host's cell and preventing the infection, the antiviral potency against FCV is based on inhibition at late stages of the viral replication cycle. Altogether, PSSNa polymers are promising drug candidates to be used in the treatment and prevention of the viral upper respiratory tract disease (URTD), regardless of the cause.

Genomic, Recombinational and Phylogenetic Characterization of Global Feline Herpesvirus 1 Isolates

Feline herpes virus type 1 (FHV-1) is widely considered to be the leading cause of ocular disease in cats and has been implicated in upper respiratory tract infections. Little, however is known about interstrain phylogenetic relationships, and details of the genomic structure. For the present study, twenty-six FHV-1 isolates from different cats in animal shelters were collected from eight separate locations in the USA, and the genomes sequenced. Genomic characterization of these isolates includied short sequence repeat (SSR) detection, with fewer SSRs detected, compared to herpes simplex viruses type 1 and 2. For phylogenetic and recombination analysis, 27 previously sequenced isolates of FHV-1 were combined with the 26 strains sequenced for the present study. The overall genomic interstrain genetic distance between all available isolates was 0.093%. Phylogenetic analysis identified four main FHV-1 clades primarily corresponding to geographical collection site. Recombination analysis suggested that interclade recombination has occurred.

Phylogenetic and recombination analysis of the herpesvirus genus varicellovirus

BACKGROUND

The varicelloviruses comprise a genus within the alphaherpesvirus subfamily, and infect both humans and other mammals. Recently, next-generation sequencing has been used to generate genomic sequences of several members of the Varicellovirus genus. Here, currently available varicellovirus genomic sequences were used for phylogenetic, recombination, and genetic distance analysis.

RESULTS

A phylogenetic network including genomic sequences of individual species, was generated and suggested a potential restriction between the ungulate and non-ungulate viruses. Intraspecies genetic distances were higher in the ungulate viruses (pseudorabies virus (SuHV-1) 1.65%, bovine herpes virus type 1 (BHV-1) 0.81%, equine herpes virus type 1 (EHV-1) 0.79%, equine herpes virus type 4 (EHV-4) 0.16%) than non-ungulate viruses (feline herpes virus type 1 (FHV-1) 0.0089%, canine herpes virus type 1 (CHV-1) 0.005%, varicella-zoster virus (VZV) 0.136%). The G + C content of the ungulate viruses was also higher (SuHV-1 73.6%, BHV-1 72.6%, EHV-1 56.6%, EHV-4 50.5%) compared to the non-ungulate viruses (FHV-1 45.8%, CHV-1 31.6%, VZV 45.8%), which suggests a possible link between G + C content and intraspecies genetic diversity. Varicellovirus clade nomenclature is variable across different species, and we propose a standardization based on genomic genetic distance. A recent study reported no recombination between sequenced FHV-1 strains, however in the present study, both splitstree, bootscan, and PHI analysis indicated recombination. We also found that the recently sequenced Brazilian CHV-1 strain BTU-1 may contain a genetic signal in the UL50 gene from an unknown varicellovirus.

CONCLUSION

Together, the data contribute to a greater understanding of varicellovirus genomics, and we also suggest a new clade nomenclature scheme based on genetic distances.

Dellen and corneal perforation after bilateral pterygium excision in a patient with no risk factors

Corneal perforation associated with dellen is a rare but serious complication of a primary pterygium excision. In this case report, we describe a 60-year-old man who underwent a corneal perforation in the centre of corneal dellen in his right eye and corneal dellen in his left eye after the surgical treatment of a bilateral pterygium with a bare sclera technique without adjunctive therapy. He was successfully treated with lamellar keratoplasty in his right eye and a conservative approach in his left eye, consisting of the use of artificial tears, antibiotic ointment and a patch. The clinical evidence from this brief interventional case report indicates that topical lubricants are proper therapy for corneal dellen. However, if corneal perforation is observed, lamellar keratoplasty is a good option.

ABCD: Update of the 2009 guidelines on prevention and management of feline infectious diseases

OVERVIEW

In this article, the ABCD guidelines published in the JFMS Special Issue of July 2009 (Volume 11, Issue 7, pages 527-620) are updated by including previously unavailable and novel information. For a better picture, the reader is advised to consult that issue before focusing on the novel features.

Felid herpesvirus type 1 infection in cats: a natural host model for alphaherpesvirus pathogenesis

Feline herpesvirus 1 (FeHV-1) is an alphaherpesvirus that causes feline viral rhinotracheitis, an important viral disease of cats on a worldwide basis. Acute FeHV-1 infection is associated with both upper respiratory and ocular signs. Following the acute phase of the disease lifelong latency is established, primarily in sensory neuronal cells. As is the case with human herpes simplex viruses, latency reactivation can result in recrudescence, which can manifest itself in the form of serious ocular lesions. FeHV-1 infection in cats is a natural host model that is useful for the identification of viral virulence genes that play a role in replication at the mucosal portals of entry or are mediators of the establishment, maintenance, or reactivation of latency. It is also a model system for defining innate and adaptive immunity mechanisms and for immunization strategies that can lead to better protection against this and other alphaherpesvirus infections.

Selkirk Rex: morphological and genetic characterization of a new cat breed

Rexoid, curly hair mutations have been selected to develop new domestic cat breeds. The Selkirk Rex is the most recently established curly-coated cat breed originating from a spontaneous mutation that was discovered in the United States in 1987. Unlike the earlier and well-established Cornish and Devon Rex breeds with curly-coat mutations, the Selkirk Rex mutation is suggested as autosomal dominant and has a different curl phenotype. This study provides a genetic analysis of the Selkirk Rex breed. An informal segregation analysis of genetically proven matings supported an autosomal, incomplete dominant expression of the curly trait in the Selkirk Rex. Homozygous curl cats can be distinguished from heterozygous cats by head and body type, as well as the presentation of the hair curl. Bayesian clustering of short tandem repeat (STR) genotypes from 31 cats that represent the future breeding stock supported the close relationship of the Selkirk Rex to the British Shorthair, Scottish Fold, Persian, and Exotic Shorthair, suggesting the Selkirk as part of the Persian breed family. The high heterozygosity of 0.630 and the low mean inbreeding coefficient of 0.057 suggest that Selkirk Rex has a diverse genetic foundation. A new locus for Selkirk autosomal dominant Rex, SADRE, is suggested for the curly trait.

Feline calicivirus: a neglected cause of feline ocular surface infections?

OBJECTIVE

To investigate the prevalence of feline calicivirus (FCV) infection in relation to ocular surface lesions in cats with upper respiratory tract diseases (URTD).

ANIMALS STUDIED

Ninety-nine cats with ocular surface infection and symptoms or recent history of URTD were examined at various rescue shelters and hospitals.

PROCEDURE

A complete general and ophthalmic examination was performed including Schirmer tear test, slit-lamp biomicroscopy, fluorescein and lissamine green staining. Clinical and ocular symptoms were scored and recorded. Conjunctival samples were collected using a cytobrush, and nucleic acid extraction using RT-PCR was carried out to analyze for the presence of various infectious agents.

RESULTS

RT-PCR detected either FCV, feline herpes virus type 1 (FHV-1), Chlamydophila felis or Mycoplasma spp. in 63/99 samples. 30/63 samples were positive for FCV, 23/63 for C. felis, 21/63 for Mycoplasma spp., and 16/63 for FHV-1. Out of the 30 FCV-positive samples, 11 were positive only for FCV and in 19 samples FCV was seen in combination with other agents. FCV infection was highest in animals examined at the rescue centers and in the age group of 0-2 months. Erosive conjunctivitis was an important ocular finding. Oral ulcers were detected in all FCV-infected cats.

CONCLUSION

Results indicate that FCV is highly prevalent in cats with URTD either as a sole infectious agent or in combination with other pathogens and therefore is a potential cause for ocular surface lesions during the URTD.

Treatment of Corneal Ulcers: What are the Medical Options?

Practical relevance Corneal ulcers in cats (ulcerative keratitis) are a common presenting complaint, and are a frequent sequela to feline herpesvirus (FHV-1) infection. In fact, it is fair to assume an FHV-1 aetiology until proven otherwise. In practice, therefore, many cases of corneal ulceration can be treated medically, but treatment can frequently be challenging, with the need to tailor therapy carefully to the type of ulcer, the individual cat and its temperament.

Patient group All age groups and breeds can suffer with ulcerative keratitis although some breeds are over-represented for some types of corneal ulceration.

Evidence base The scientific literature on feline ulcerative keratitis is extensive, particularly that related to FHV-1 infection. This article reviews the medical treatment options for corneal ulceration in cats with reference to the current evidence base.

Treatment of corneal ulcers: when is surgery indicated?

PRACTICAL RELEVANCE

While corneal ulcers in cats frequently arise secondarily to feline herpesvirus (FHV-1) infection, and thus medical therapy is often indicated, other causes include trauma, eyelid abnormalities (agenesis, entropion, dermoids and neoplasia), tear film abnormalities and neurological deficiencies (trigeminal nerve paralysis or facial nerve paralysis). In some such cases, surgery is required. Treatment always needs to be tailored carefully according to the depth and progression of the ulcer, any concurrent ophthalmic disease, the patient's general health and demeanour, and owner compliance and financial circumstances.

PATIENT GROUP

All age groups and breeds can suffer with ulcerative keratitis although some breeds are over-represented for some types of corneal ulceration.

EVIDENCE BASE

The scientific literature on feline ulcerative keratitis is extensive. This article reviews the surgical indications for corneal ulceration in cats with reference to the current evidence base.