Back to home page

Interferon in cats with FeLV

Clinical Scenario

Sherbert is a 3 year old female neutered domestic shorthair that presented to you for weight loss. On clinical examination she has a body condition score of 1/5, is bright but her mucous membranes are very pale with a capillary refill time of 2 seconds. Her owner has noticed no abnormalities other than weight loss. Her PCV is 12% and the anaemia is non-regenerative but there is some autoagglutination on the slide. A patient side test is positive for FeLV and negative for FIV. You have sent some blood away for confirmatory testing but in the meantime you suggest her owner separates her from the other cats in the house. You are unsure what to prescribe and consider immunosuppressives and interferon, you wonder if there is any evidence supporting the using of feline interferon in cats like Sherbert  .....

3-Part Question (PICO)

In [cats with persistent FeLV infection] does [the use of feline interferon omega in combination with supportive therapy compared to supportive therapy alone] improve [the clinical signs of infection]?

Search Strategy and Summary of Evidence

Search Strategy

MEDLINE(R) In-Process & Other Non-Indexed Citations and MEDLINE(R) 1946 to Present using the OVID interface

(cat.mp OR cats.mp OR feline.mp OR felines.mp OR felis.mp. OR exp Cats/)

AND

(feline leukaemia virus.mp. OR feline leukemia virus.mp. OR felv.mp.)

AND

(ifn.mp. OR ifns.mp. OR interferon.mp. OR interferons.mp. OR virbagen omega.mp.)

CAB Abstracts 1910 to Present using the OVID interface

(cat.mp OR cats.mp OR feline.mp OR felines.mp OR felis.mp. OR exp Cats/)

AND

(feline leukaemia virus.mp. OR feline leukemia virus.mp. OR felv.mp.OR exp feline leukaemia virus/)

AND

(ifn.mp. or ifns.mp. or interferon.mp. or interferons.mp. or virbagen omega.mp. OR exp Interferon/)

Search Outcome

MEDLINE

  • 47 papers found in MEDLINE search
  • 43 papers excluded as they don't meet the PICO question
  • 0 papers excluded as they are in a foreign language
  • 3 papers excluded as they are review articles/in vitro research/conference proceedings
  • 1 total relevant papers from MEDLINE

CAB Abstracts

  • 65 papers found in CAB search
  • 50 papers excluded as they don't meet the PICO question
  • 9 papers excluded as they are in a foreign language
  • 5 papers excluded as they are review articles/in vitro research/conference proceedings
  • 1 total relevant papers from CAB

Total relevant papers

1 relevant papers from both MEDLINE and CAB Abstracts

Summary of Evidence

De Mari, K et al. 2004, USA

Title:

Therapeutic effects of recombinant feline interferon-omega on feline leukemia virus (FeLV)-infected and FeLV/feline immunodeficiency virus (FIV)-coinfected symptomatic cats

Patient group:

Cats with FeLV/FeLV and FIV. N= 81 cats

Study Type:

Randomised, controlled trial

Outcomes:
  • Clinical sign severity scores based on a scale of 0-3 for the following parameters: Rectal temperature, general behaviour, appetite, thirst dehydration, mucous membrane appearance, stomatitis and death (given a score of 20).
  • Blood samples collected -  White blood cell count, Red blood cell count and packed cell volume
  • Haematologic parameters in subgroups of cats with initial abnormalities (anaemia, leukopaenia, leucocytosis)
Key Results:
  • No significant differences in clinical signs between groups during the study.
  • The mortality in the IFN treated group was 39% and 59% in the placebo group at 9 months (p=0.049)
  • 5 cats in the study had adverse events including lethargy, vomiting and diarrhoea. No statistical difference between groups.
  • No significant differences in haematological parameters between groups overall
  • However, some increase in PCV in treated cats which were initially anaemic, and some ‘correction’ of parameters in cats initially presented with leucocytosis/ leukopaenia
Study Weaknesses:
  • No clear aim of this study is stated in the paper.
  • Method of randomisation not stated.
  • No sample size/power calculation was performed.
  • Other than on the first day of treatment, it was not clear which cats were infected with FeLV alone and which cats were FeLV/FIV co-infected.
  • Many cats lost to follow-up over the course of the study so it is unclear how many cats are in the statistical analysis for many outcomes
    Subgroup analyses performed on very small numbers of cats
Attachment:
No attachments.

Comments

The cats were diagnosed as FeLV or FeLV/FIV co-infected using an ELISA and no confirmatory tests were undertaken. In general these tests are not seen as a gold standard for retrovirus diagnosis.
No power calculation was done, no p value stated in the methods as significant, and many cats were lost to follow-up which means the results of this study are very hard to interpret.

 

Bottom line

The evidence would suggest that Interferon omega has no significant effect on clinical signs of infection but may improve haematological parameters in some cats.

Disclaimer

The BETs on this website are a summary of the evidence found on a topic and are not clinical guidelines. It is the responsibility of the individual veterinary surgeon to ensure appropriate decisions are made based on the specific circumstances of patients under their care, taking into account other factors such as local licensing regulations. Read small print

References

De Mari K, Maynard L, Sanquer A, Lebreux B, Eun HM. Therapeutic effects of recombinant feline interferon-omega on feline leukemia virus (FeLV)-infected and FeLV/feline immunodeficiency virus (FIV)-coinfected symptomatic cats.   J Vet Intern Med. (2004);18(4):477-82.

 

About this BET

First author:
Rachel Dean
Second author:
Jenny Stavisky
Institution:

CEVM, University of Nottingham

Search last performed:
2016-03-02 11:06:48
Original publication date:
2013-09-13 11:06:48
Last updated:
2016-03-02 11:06:48
About BETs?

A BET is a simple method of searching for and appraising evidence around a very specific clinical situation.

Read more …

Using BETs?

BETs don’t tell you what to do, they tell you about the evidence on a certain topic.

Read more …

Not a Vet?

This website has been designed to help vets use the best, most relevant, up to date science when they make decisions about their patients.

Read more …