Today's Veterinary Practice

MAR-APR 2018

Today's Veterinary Practice provides comprehensive information to keep every small animal practitioner up to date on companion animal medicine and surgery as well as practice building and management.

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PEER REVIEWED 72 FOCUS ON virus, peste des petits ruminants virus, phocine distemper virus, CDV, dolphin morbillivirus, porpoise morbillivirus, equine morbillivirus (Hendra virus), and porcine morbillivirus (Menangle virus) 6 —the primary cause of distemper in ferrets is infection with CDV. 8 EPIDEMIOLOGY Several outbreaks of CDV infections in ferrets have been documented throughout the world over the past 10 years. In an outbreak of distemper in Spain in 2006, 14 domestic ferrets died. 4 Three confirmed cases of CDV infections in ferrets that were euthanized in 2006, 2012, and 2013 were reported in New South Wales and the Australian Capital Territory. 1 Two cases of distemper in domestic ferrets were reported in Germany in 2006. 10 A major outbreak of distemper was reported in Denmark in 2012. Danish farmed mink (Neovison vison) were mainly affected. In a study of this outbreak, Trebbien showed that carnivores (foxes, raccoons, dogs, and ferrets) in that area affected by the disease died of CDV, showing an identity at the nucleotide level of 99.45% to 100%. 9 In the United States, free-ranging raccoons (Procyon lotor) are the main species affected by CDV in wildlife, serving as a potential disease reservoir. 3 A large outbreak of distemper in raccoons living around a large suburban zoo in the United States was reported in 2001. 11 PATHOGENESIS Infections caused by a morbillivirus are spread by aerosol transmission and show a highly contagious pattern. Contact with exudates (eg, conjunctival and nasal), urine, feces, and skin is often a source of transmission. The virus shows a strong affinity for epithelial cells and lymphoid tissue of the upper respiratory tract. This is where the first phase of viral replication occurs. 6 Clinically, this phase is observed 3 to 6 days after infection. It is characterized by lymphopenia and pyrexia. The patient has viremia at this point, resulting in systemic infection of the lymphatic tissue. There is a strong correlation of immunosuppression and virulence. The fever is biphasic and recurs in the second phase of viremia a few days later. The systemic infection of the epithelial cells severely affects the patient, resulting in damage to the mucosal tissue. At this stage, patients show serous nasal discharge, conjunctivitis, and anorexia, clinically resembling an influenza infection ( FIGURE 2 ). Dermatologic signs, including facial and perineal dermatitis, as well as dermatitis on the abdomen, completely resolve between 17 and 22 days after infection. 12 The entire respiratory and gastrointestinal tract can be severely affected, and disturbance of the epithelial cell layer predisposes patients to secondary bacterial infections. 6 Because of the clinical resemblance to influenza infectious, it is important to diagnose distemper early to avoid potential shedding of the virus and potential contamination of the clinic. Neurologic signs resulting from acute encephalomyelitis have been described but are not always present in affected animals. Of note, during the previously mentioned 2006 outbreak in Spain, none of the affected animals showed any neurologic signs. 4 Depending on the strain of the virus, patients may be moribund after 16 days of infection, a condition that justifies humane euthanasia or results in death. Dermatologic signs, such as hyperkeratosis of footpads or the nasal plane, as observed in canines, are rare 12 ( FIGURE 3 ). FIGURE 2. The catarrhal phase of CDV involves anorexia, pyrexia, photosensitivity, and serous nasal discharge. Mucopurulent ocular and nasal discharge with possible bacterial pneumonia may be seen with a secondary bacterial infection, which resembles an influenza infection. Photo courtesy of Dr. Jeff Baier FIGURE 3. The hard pad lesions on affected ferrets are usually not as pronounced as those on dogs, most likely because of the rapid progression of the disease. Photo courtesy of Dr. Jeff Baier

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