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Canine Herpesvirus
Yvonne Drechsler, PhD

College of Veterinary Medicine, Western University of Health Sciences, Pomona, CA, USA

Etiology/Pathophysiology Signalment

Canine herpesvirus (CHV), a member of the Herpesviridae Neonatal puppies up to 3 weeks are at greatest risk for
family, is a DNA virus that infects and replicates in severe disease and death. Male and female dogs older
mucosal epithelial cells and lymphoid tissue. Clinical signs than 3 weeks generally develop mild clinical signs and
vary depending on the age and immune status at time of recurring infections.
infection. The virus replicates most efficiently at tempera-
tures lower than 98.6 °F. Therefore, the ability to mount a
febrile response aids in fighting infection. In addition, rep- History and Clinical Signs
lication is favored in cooler body locations such as mucous
membranes. As is common for herpesviruses, CHV will Infection and associated clinical signs occur by exposure
exist as a latent form in ganglia or lymphoid tissue after to other dogs, and may be particularly common in ken-
initial infection. The virus can be reactivated by stressors nels and other multidog environments. Clinical signs
at any time, leading to shedding and transmission. may also occur due to reactivation of previous infection
In naive pregnant females, infection will lead to sys- provoked by various stressors. Immunocompromised
temic viremia, resulting in fetal death, abortion, and animals are at higher risk of reoccurring infections, par-
mummification. Puppies typically acquire the infection ticularly dogs with diabetes mellitus, immune‐mediated
in utero, during passage through the birth canal, via con- diseases, and lymphoma.
tact with oronasal secretions of the dam, or from contact In young puppies 1–3 weeks of age, signs include depres-
with other infected dogs shedding the virus. Acute neo- sion, respiratory signs, anorexia, soft yellow or green stools
natal viremia is associated with very high mortality in and diarrhea, persistent crying, abdominal pain, petechial
puppies younger than 3 weeks. Pregnant females, previ- hemorrhages on mucous membranes and occasional pres-
ously exposed to the virus, will confer passive immunity ence of vesicles on genitals. Death usually occurs within
through nursing, while remaining asymptomatic. Older, 24–48 hours of showing clinical signs. Surviving puppies
naive puppies and adult dogs will usually show disease of will most likely develop neurologic signs.
the genitals, respiratory tract or eyes. Older puppies and adults may present with upper res-
piratory signs, but in rare cases, more severe lower res-
piratory disease can occur. Signs of primary genital
Epidemiology infection are characterized by vesicular lesions on the
genital mucosa. Ocular signs may include conjunctivitis,
Canine herpesvirus is common in several canine species, corneal ulceration or keratitis, blepharospasm, photo-
including dogs, coyotes, and wolves, and has a world- phobia, and ocular discharge.
wide distribution. Studies in Europe have shown a sero-
prevalence of 39–88% in dogs. Infection is more common
in multidog environments, such as shelters and kennels. Diagnosis
Studies in shelter dogs have also shown that CHV may be
implicated as an etiologic agent in canine infectious res- History, clinical signs, physical examination, a history
piratory disease complex. of stress or evidence of immunosuppression should
Clinical Small Animal Internal Medicine Volume II, First Edition. Edited by David S. Bruyette.
© 2020 John Wiley & Sons, Inc. Published 2020 by John Wiley & Sons, Inc.
Companion website: www.wiley.com/go/bruyette/clinical