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Efficacy of antibodies therapy in cats with upper respiratory tract infections

Freidl Y, Schulz B, Knebl A, et al. Efficacy of passively transferred antibodies in cats with acute viral upper respiratory tract infection. Vet J. 2014 Sep; 201(3): 316-321.

Acute viral upper respiratory tract infections (URTI) in cats are common and can be caused by several pathogens. The two most common viruses involved, feline calicivirus (FCV) and feline herpesvirus-1 (FHV-1), account for at least 80% of feline upper respiratory tract disease (FURTD). In the nature of their infections, FHV-1 can develop a latency state where cats become carriers and will shed virus during a period of recrudescence, while FCV-infected cats can also become carriers but virus is shed more persistently.

In Germany, a commercial product, Feliserin (IDT Biologika), is advertised to contain antibodies against FCV, FHV-1, and feline panleukopenia. Efficacy of the product has not been sufficiently appraised in scientific studies. The investigators in this study performed a randomized, placebo-controlled, double-blind clinical trial to evaluate the efficacy of passively transferred antibodies given to cats with acute viral URTD caused by FCV and/or FHV-1. Included in the study were 42 cats with clinical signs of URTI of less than seven days duration. FCV and/or FHV-1 infection was confirmed by quantitative polymerase chain reaction from swabs of nasal/throat area and/or conjunctiva.  The hyperimmune serum (passively transferred antibodies) was given to 22 cats in one group and an equal amount of saline was given to a control group of 20 cats as a placebo for 3 consecutive days. For the young cats in the treatment group, cats ≤ 12 weeks of age received 2 ml while cats ≥ 12 weeks of age were administered 4 ml of serum subcutaneously once daily and a topically applied to eyes, nostrils, and the mouth every 8 hours. Scoring was recorded daily for 8 days and then again on day 21, including a ‘score for FURTD’ and the cat’s general health status.  Quantitative PCR was performed on days 0 and 21 to check for FCV shedding.

Results from the study demonstrated that clinical signs and health status significantly improved in both groups over time. The treatment group given the hyperimmune serum significantly improved in their ‘FURTD scoring’ and general health status by day 3 where the placebo group showed significant improvement later in time, by day 7. The cats shedding FCV did not exhibit any significant difference in the amount of virus shedding between the two groups over the trial period. This study indicates that Feliserin delivered systemically and topically to cats with acute URTIs did result in a quicker improvement in the ‘FURTD score’ and overall general health status compared to cats treated with placebo, 3 days versus 7 days. No adverse effects were noted with the Feliserin treated cats. The results raise the question if the more rapid resolution of most clinical signs by using hyperimmune serum in a period of 4 days justifies the additional expense and potential stress of administering the treatment. (VT)

See also:
Ballin AC, Schulz B, Helps C, et al. Limited efficacy of topical recombinant feline interferon-omega for treatment of cats with acute upper respiratory viral disease. Vet J. 2014 Oct 6; epub.