*5.9.2 Interferons and biological response modifiers*

The interferon (IFN)-ω, a type I IFN (similar to IFN-α), is known for its antiviral, anti-proliferation, and antitumor activities. A notable therapeutic effect of rIFN-ω on CPV-infected dogs is reported [114]. Additionally, the promising therapeutic potential of other type I (IFN-α, IFN-β, IFN-ε, and IFN-κ) and III (IFN-λ) IFNs in CPVE has also been reported [115].

Recently, anti-CPV activity of the serum derived transfer factors (TFs), low molecular weight (<5000 daltons) biological response modifiers has been documented. It imparts therapeutic benefit in CPVE by altering the cytokine response of the host [116].

## **5.10 Probiotics**

Probiotics, primarily comprised of live microorganisms in fermented foods, protect gut from acute diarrhea through adherence and colonization on gut mucosa [117]. Therapeutic efficacy of probiotics has been verified in dogs with CPV associated illnesses [118]. In an earlier study, oral administration of probiotic preparations as an adjunct therapy to young dogs with CPVE has shown faster resolution of clinical signs, improved leukogram and decreased mortality as compared to supportive treatment alone [119]; whereas, no benefit with respect to length of hospital stay or case fatality was recorded in other study [120].

### **5.11 Antioxidants**

The disturbance in oxidant/antioxidant equilibrium is evident in CPVgastroenteritis and oxidative stress is believed to link with pathogenesis of CPVE [121]. Hence, addition of antioxidants in supportive therapy has emerged as a promising therapeutic option to improve the response of treatment in viral diseases. Treatment with *N-*acetylcysteine (NAC), a precursor to glutathione and the body's primary cellular antioxidant, along with supportive therapy markedly improved the leukogram in dogs with CPVE when compared with supportive therapy alone [122].
