**5.3 Antiemetic treatment**

Apart from fluid and electrolyte imbalance, emesis is another clinical manifestation in CPVE. So, antiemetic treatment is warranted in CPVE otherwise persistent vomition may enhance the duration of hospital stay and further aggravates the condition of patient. The clinical efficacy of number of antiemetics in CPVE had been investigated with varying degree of results. The earlier studies showed that metoclopramide, a dopaminergic antagonist, was found to be effective in reducing episode of vomition by exerting a prokinetic effect in the upper intestinal tract and blocking the chemoreceptor trigger zone when administered as a bolus or as a constant-rate infusion in dogs. The ondasetron or dolasetron, the serotonin receptor antagonists, are also found effective in reducing the number of vomiting events [85]. Recently, a substantial antiemetic effect of maropitant, an antagonist of neurokinin1 receptors, by stimulation of either central or peripheral emetic pathways has been reported in dogs however, the efficacy of maropitant in CPVE has yet to be thoroughly investigated [91]. The administration of maropitant once daily, singly or in combination with metoclopramide, is very effective in reducing vomition in CPVE [5].

### **5.4 Antimicrobial treatment**

Translocation of bacteria from intestinal compartment to systemic circulation is very common in CPVE because of villous collapse and disruption of the mucosal barrier. The translocation with concurrent marked neutropenia leads to a high risk of septicemia and endotoxemia. Additionally, hypotension from fluid loss and sepsis make dogs with CPVE at high risk of developing acute kidney injury. Therefore, parenteral administration of broad-spectrum bactericidal antibiotics is necessary in dogs with CPVE. Ampicillin and cefoxitin as single-agent treatments or in combination with enrofloxacin are the choice antimicrobials against Gram-positive and negative bacteria [85]. Aminoglycosides may also be considered in well-hydrated animals otherwise it may be avoided due to its inherent risk of nephrotoxicity. Puppies with CPVE often have comorbidities, including gastrointestinal parasitism. Hence, antiparasite therapy should be initiated once the puppy can tolerate oral therapies [6].

### **5.5 Nutritional support and pain management**

Restoration of early mucosal integrity and prevention of bacterial translocation from gut compartment to systemic circulation are very important for faster recovery of dogs with CPVE. Enteral feeding is reported to improve the mucosal integrity and faster repair, resulting in lower possibilities for bacterial translocation [8]. In earlier study, it was demonstrated that early enteral nutrition via

*Canine Parvovirus-2: An Emerging Threat to Young Pets DOI: http://dx.doi.org/10.5772/intechopen.104846*

nasoesophageal catheter starting 12 hours post-admission led to clinical improvement, significant weight gain, and improved gut barrier function was more early as compared to withholding of the traditional food until cessation of vomiting for 12 hours [92].

Severe vomition, enteritis, and or concurrent intussusception in CPVE are the possible reasons for abdominal pain. Hence, analgesic treatment to reduce visceral pain is one the important aspect in therapeutic management in CPVE. Partial muagonists such as buprenorphine (0.01–0.02 mg/kg IV every 8 hours) or an agonist– antagonist such as butorphanol (0.1–0.2 mg/kg/h) are the preferred analgesics over the pure mu agonists as opioid analgesics can promote ileus and vomiting. The α-2 agonists that promote extreme vasoconstriction and limit gastrointestinal perfusion, and non-steroidal anti-inflammatory drugs that impair gastrointestinal and renal perfusion, both are not indicated [93].

#### **5.6 Antiviral drugs**

Like other viral infections, prophylaxis is the cornerstone for prevention of CPV in dogs. Although, an adequate number of killed and live CPV vaccines are marketed by pharmaceuticals but vaccines sometimes fail to protect completely due to poorly responding breeds (Rottweilers and Doberman pinschers), variation in genetic makeup of field and vaccine viruses, interference by presence of maternal antibodies and adjunct factors [94]. Therefore, development of some suitable antiviral drugs is utmost important for effective management of the CPVE in its acute illness stage. Till now, only few antiviral drugs have been evaluated for its clinical efficacy against CPVE. In an earlier placebo-control study, the therapeutic efficacy of Oseltamivir, a neuraminidase inhibitor, in CPVE had been evaluated and noted that Oseltamivir did not produce any additional benefit in terms of reduction of mortality or duration of hospitalization except some improvements in body weight and hemogram in dogs with CPV-illness [95]. In another study on naturally infected dogs, a promising anti-CPV activity of recombinant feline interferon-ω (rFeIFN-ω) has been recorded as compared to placebo-group. The intravenous administration of rFeIFN-ω at the dose rate of 2.5 mU/kg daily for consecutive three days remarkably reduced the clinical symptoms and mortality [96, 97]. Although the drug is currently available for use in Europe and Australia, the high price and frequent non-availability are major limitations. Recently, another antivital drug, Acyclovir, guanine analogue commonly used to treat herpes simplex virus infection, have been shown to improve the disease conditions [98]. Further, an *in-vitro* study on A72 cell line showed that 9-(2- hydroxyethomethyl) guanine phosphoromonomorpholidate (ACV PMMPD), a phosphorimidate analogue of acyclovir inhibits CPV-2 replication with exhibiting 50% inhibitory concentrations (IC50s) in the low-micromolar range (50 μM) [99]. Recently, broadspectrum anti-CPV activity of some anti-parasitic drugs such as Nitazoxanide, Closantel Sodium, and Closantel have also been shown using F81 cells [100].

#### **5.7 Passive immunotherapy**

Passive immunization with specific antibodies against enteric viral infections in animals confers significant protection, reduces diarrhea and virus shedding and increase survival rates [101]. Thus, the of immunotherapeutics in viral infections is promising treatment approach because of lower adverse effects as well as no chance of any resistance as in antiviral drugs. The passive immunization by means of oral

or intravenous administration of IgY specific for CPV-2 shows the protective effect in dogs challenged with the virus [102]. The reduction of clinical scores, duration of symptoms and mortality and improvement of body weight gain has been reported by anti-CPV-2 IgY therapy in experimentally produced CPVE [103]. Recent study reported that chicken IgY- single chain fragment variables (scFv) generated against the virus capsid protein could be a promising therapeutic target against CPV [104, 105]. Aside from IgY, the neutralization of CPV by anti-feline panleukopenia virus antibodies is also reported from an *in-vitro* study [106]. However, the prospective, randomized, placebo-controlled, double-blinded study on CPVE did not produce substantial benefits when compared with placebo group [86]. Apart from above therapeutics, plasma therapy is also another option. Although the administration of CPV-hyperimmune plasma is reported to decrease the clinical signs and improve the survival rate in dogs under experimental conditions, however the findings remain inconclusive in natural cases [107]. Another study showed that lyophilized IgG treatment reduced clinical signs and duration of hospitalization of dogs naturally infected with CPV [108].
