Title: Canine distemper

{{Short description|Viral disease affecting some mammals}}
{{Virusbox
| name = Canine distemper virus
| image = Canine Distemper Virus Cytoplasmic Inclusion Body (Blood smear, Wright's stain).jpg
| image_alt = Canine distemper virus cytoplasmic inclusion body (blood smear, Wright's stain)
| image_caption = Canine distemper virus cytoplasmic inclusion body (blood smear, Wright's stain)
| parent = Morbillivirus
| species = Morbillivirus canis
| synonyms = ''Canine distemper virus''
| synonyms_ref = &lt;ref name=&quot;ICTVcm&quot;&gt;{{cite web |title=ICTV Taxonomy history: ''Canine morbillivirus'' |url=https://ictv.global/taxonomy/taxondetails?taxnode_id=20181613 |website=International Committee on Taxonomy of Viruses (ICTV) |access-date=15 January 2019}}&lt;/ref&gt;
}}

'''Canine distemper''' ('''CDV''') (sometimes termed &quot;'''footpad disease'''&quot;) is a [[virus|viral]] [[disease]] that affects a wide variety of mammal families,&lt;ref&gt;{{ Cite journal | url=http://www.cabi.org/isc/datasheet/121101 | title=canine distemper – Invasive Species Compendium – CABI | date=2015 | doi=10.1079/cabicompendium.121101 | last1=Whitehouse | first1=Chris A. | journal=CABI Compendium | volume=CABI Compendium | doi-access=free }}&lt;/ref&gt; including domestic and wild species of [[dogs]], [[coyotes]], [[foxes]], [[Giant panda|pandas]], [[wolves]], [[ferrets]], [[skunks]], [[raccoons]], and [[Felidae|felines]], as well as [[pinnipeds]], some primates, and a variety of other species.  CDV does not affect humans.

In canines, CDV affects several body systems, including the gastrointestinal and respiratory tracts, the spinal cord, and the brain. Common symptoms include high fever, eye inflammation and eye/nose discharge, labored breathing and coughing, vomiting and diarrhea, loss of appetite and [[lethargy]], and hardening of the nose and footpads. The viral infection can be accompanied by secondary bacterial infections and can eventually present serious neurological symptoms.

Canine distemper is caused by a single-stranded [[RNA virus]] of the family ''[[Paramyxoviridae]]'' (the same family of viruses that causes [[measles]] and [[mumps]] in humans). The disease is highly contagious via inhalation.&lt;ref name=Deemetal2000&gt;{{cite journal |last1=Deem |first1=Sharon L. |last2=Spelman |first2=Lucy H. |last3=Yates |first3=Rebecca A. |last4=Montali |first4=Richard J. |date=December 2000 |title=Canine Distemper in Terrestrial Carnivores: A Review |url=http://www.allthingscanid.org/caninedistemper.pdf |journal=Journal of Zoo and Wildlife Medicine |volume=31 |issue=4 |pages=441–451 |doi=10.1638/1042-7260(2000)031[0441:CDITCA]2.0.CO;2 |pmid=11428391 |s2cid=12596794 |access-date=2017-12-05 |url-status=live |archive-url=https://web.archive.org/web/20170517020346/http://www.allthingscanid.org/caninedistemper.pdf |archive-date=2017-05-17 }}&lt;/ref&gt; Morbidity and mortality may vary greatly among animal species, with up to 100% mortality in unvaccinated populations of ferrets. In domestic dogs, while the acute generalized form of distemper has a high mortality rate, disease duration and severity depend mainly on the animal's age, immune status, and  the virulence of the infecting strain of the virus.&lt;ref name=Deemetal2000/&gt;&lt;ref&gt;{{cite journal|title=Cross-species transmission of canine distemper virus – an update|journal=One Health|date=13 September 2015|last1=Andreas|first1=Beineke|last2=Baumgärtner|first2=Wolfgang|last3=Wohlsein|first3=Peter|pmc=5462633|volume=1 |pages=49–59 |doi=10.1016/j.onehlt.2015.09.002 |pmid=28616465}}&lt;/ref&gt; Despite extensive vaccination in many regions, it remains a major disease in dogs and was the leading cause of infectious disease death in dogs prior to a vaccine becoming available.&lt;ref&gt;{{cite web |url=http://lbl.global/pdf/Animal_man_packs/Animal_health_an_man/AHAC8%20-%20Infectious%20diseases%20of%20dogs.pdf |title=Animal Health |access-date=2017-10-30 |url-status=dead |archive-url=https://web.archive.org/web/20171107010341/http://lbl.global/pdf/Animal_man_packs/Animal_health_an_man/AHAC8%20-%20Infectious%20diseases%20of%20dogs.pdf |archive-date=2017-11-07 }}&lt;/ref&gt;

==Etymology==
The origin of the word ''distemper'' is from [[Middle English]] {{Lang|enm|distemperen}}, 'to upset the balance of the [[Humorism|humors]],' which is from [[Old French]] {{Lang|fro|destemprer}}'','' 'to disturb,' which is from [[Vulgar Latin]] {{Lang|la|distemperare}}, 'to not mix properly.'&lt;ref&gt;{{cite web |url=https://en.oxforddictionaries.com/definition/distemper |author=&lt;!--Not stated--&gt; |title=distemper (definition) |publisher=Oxford University Press |website=Oxford Living Dictionaries – English |access-date=2017-12-06 |url-status=dead |archive-url=https://web.archive.org/web/20171206213509/https://en.oxforddictionaries.com/definition/distemper |archive-date=2017-12-06 }}&lt;/ref&gt;&lt;ref&gt;{{cite web |url=https://ahdictionary.com/word/search.html?q=distemper |author=&lt;!--Not stated--&gt; |title=distemper (definition) |publisher=Houghton Mifflin Harcourt |website=American Heritage Dictionary |access-date=2017-12-06 |url-status=live |archive-url=https://web.archive.org/web/20180509140620/https://ahdictionary.com/word/search.html?q=distemper |archive-date=2018-05-09 }}&lt;/ref&gt;

==History==
In Europe, the first report of CDV occurred in Spain in 1761.&lt;ref name=&quot;Appel 1972&quot;/&gt; [[Edward Jenner]] described the disease in 1809,&lt;ref name=&quot;Appel 1972&quot;/&gt; and French veterinarian [[Henri Carré]] determined that the disease was caused by a [[virus]] in 1905.&lt;ref name=&quot;Appel 1972&quot;&gt;{{cite book|last1=Appel|first1=MJG|last2=Gillespie|first2=JH|title=Volume 11 of the series Virology Monographs / Die Virusforschung in Einzeldarstellungen|date=1972|publisher=Springer Vienna|location=Vienna|isbn=978-3-7091-8302-1|pages=1–96|chapter=Canine Distemper Virus}}&lt;/ref&gt; Carré's findings were disputed by researchers in England until 1926, when [[Patrick Laidlaw]] and G.W. Dunkin confirmed that the disease was, in fact, caused by a virus.&lt;ref name=&quot;Appel 1972&quot;/&gt;

The first vaccine against canine distemper was developed by the Italian Vittorio Puntoni.&lt;ref name=&quot;Tizzard 1999&quot;&gt;{{cite journal|last1=Tizard|first1=I|title=Grease, anthraxgate, and kennel cough: a revisionist history of early veterinary vaccines|journal=Advances in Veterinary Medicine|date=1999|volume=41|pages=7–24|pmid=9890006|doi=10.1016/S0065-3519(99)80005-6|isbn=9780120392421}}&lt;/ref&gt; In 1923 and 1924, Puntoni published two articles in which he added [[formalin]] to brain tissue from infected dogs to create a vaccine that successfully prevented the disease in healthy dogs.&lt;ref name=&quot;Tizzard 1999&quot;/&gt; A commercial vaccine was developed in 1950, yet owing to its limited use, the virus remains prevalent in many populations.&lt;ref name=Pomeroy2008&gt;{{cite journal |doi=10.1007/s00239-007-9040-x |title=The Evolutionary and Epidemiological Dynamics of the Paramyxoviridae |year=2008 |last1=Pomeroy |first1=Laura W. |last2=Bjørnstad |first2=Ottar N|last3=Holmes |first3=Edward C. |journal=Journal of Molecular Evolution |volume=66 |issue=2 |pages=98–106 |pmid=18217182 |pmc=3334863|bibcode=2008JMolE..66...98P }}&lt;/ref&gt;

The domestic dog has largely been responsible for introducing canine distemper to previously unexposed wildlife and now causes a serious conservation threat to many species of [[Carnivora|carnivores]] and some species of [[marsupial]]s. The virus contributed to the near-extinction of the [[black-footed ferret]]. It also may have played a considerable role in the extinction of the [[thylacine]] (Tasmanian tiger) and recurrently causes mortality among [[African Wild Dog|African wild dogs]].&lt;ref name=&quot;McCarthy2007&quot;/&gt; In 1993–1994, the lion population in the Serengeti, Tanzania, experienced a 20% decline as a result of the disease.&lt;ref name=&quot;Assessment2005&quot;&gt;{{Cite journal |last1=Weckworth |first1=Julie K. |last2=Davis |first2=Brian W. |last3=Dubovi |first3=Edward |last4=Fountain-Jones |first4=Nicholas |last5=Packer |first5=Craig |last6=Cleaveland |first6=Sarah |last7=Craft |first7=Meggan E. |last8=Eblate |first8=Ernest |last9=Schwartz |first9=Michael |last10=Mills |first10=L. Scott |last11=Roelke-Parker |first11=Melody |date=November 2020 |title=Cross-species transmission and evolutionary dynamics of canine distemper virus during a spillover in African lions of Serengeti National Park |url=https://onlinelibrary.wiley.com/doi/10.1111/mec.15449 |journal=Molecular Ecology |language=en |volume=29 |issue=22 |pages=4308–4321 |doi=10.1111/mec.15449 |pmid=32306443 |bibcode=2020MolEc..29.4308W |issn=0962-1083|url-access=subscription }}&lt;/ref&gt;&lt;ref&gt;{{Cite journal |last1=Roelke-Parker |first1=Melody E. |last2=Munson |first2=Linda |last3=Packer |first3=Craig |last4=Kock |first4=Richard |last5=Cleaveland |first5=Sarah |last6=Carpenter |first6=Margaret |last7=O'Brien |first7=Stephen J. |last8=Pospischil |first8=Andreas |last9=Hofmann-Lehmann |first9=Regina |last10=Lutz |first10=Hans |last11=Mwamengele |first11=George L. M. |last12=Mgasa |first12=M. N. |last13=Machange |first13=G. A. |last14=Summers |first14=Brian A. |last15=Appel |first15=Max J. G. |date=February 1996 |title=A canine distemper virus epidemic in Serengeti lions (Panthera leo) |journal=Nature |language=en |volume=379 |issue=6564 |pages=441–445 |doi=10.1038/379441a0 |pmid=8559247 |issn=1476-4687|pmc=7095363 |bibcode=1996Natur.379..441R }}&lt;/ref&gt;  The disease has also mutated into the [[phocid distemper virus|phocine distemper virus]], which affects [[Pinniped|seal]]s.&lt;ref name=&quot;Jones1997&quot;&gt;{{cite book|title=Veterinary Pathology|author=Jones, T.C.|author2=Hunt, R.D.|author3=King, N.W.|publisher=Blackwell Publishing|year=1997}}&lt;/ref&gt;

==Clinical signs==
In dogs, signs of CDV vary widely, from no signs to mild respiratory signs indistinguishable from [[kennel cough]] to severe pneumonia with vomiting, bloody diarrhea, and death.&lt;ref name=&quot;Greene 2012&quot;&gt;{{cite book|last1=Greene|first1=CE|last2=Vandevelde|first2=M|editor1-last=Greene|editor1-first=Craig E.|title=Infectious diseases of the dog and cat|date=2012|publisher=Elsevier/Saunders|location=St. Louis, Mo.|isbn=978-1-4160-6130-4|pages=25–42|edition=4th|chapter=Chapter 3: Canine distemper}}&lt;/ref&gt;

Commonly observed signs are a runny nose, vomiting and diarrhea, dehydration, excessive salivation, coughing and/or labored breathing, loss of appetite, and weight loss. If neurological signs develop, incontinence may ensue.&lt;ref name=&quot;Jones1997&quot;/&gt;&lt;ref&gt;{{cite book | title=Veterinary Microbiology |vauthors=Hirsh DC, Zee YC | publisher=Blackwell Publishing | year=1999 | isbn=978-0-86542-543-9 }}&lt;/ref&gt; Central nervous system signs include a localized involuntary twitching of muscles or groups of muscles, seizures with salivation, and jaw movements commonly described as &quot;chewing-gum fits,&quot; or more appropriately as &quot;distemper myoclonus.&quot; As the condition progresses, the seizures worsen and progress to [[Generalized tonic–clonic seizure|grand mal convulsions]], followed by the death of the animal. The animal may also show signs of sensitivity to light, incoordination, circling, increased sensitivity to sensory stimuli such as pain or touch, and deterioration of motor capabilities. Less commonly, they may lead to blindness and paralysis. The length of the systemic disease may be as short as 10 days, or the start of neurological signs may not occur until several weeks or months later. Those few that survive usually have a small tic or twitch of varying degrees of severity. With time, this tic usually diminishes somewhat in its severity.&lt;ref name=CreevyMerck/&gt;&lt;ref name=&quot;Jones1997&quot;/&gt;

===Lasting signs===
A dog that survives distemper can have complications afterwards.  The most prevalent complication is hard pad disease, in which the skin on paw pads and skin on end of the nose thicken. Another lasting symptom that is common is [[enamel hypoplasia]]. Puppies can have damage to the enamel of teeth that are not completely formed or have not yet grown through the gums. This results from the virus killing the cells responsible for manufacturing the tooth enamel. These affected teeth tend to erode quickly.&lt;ref name=Insider2012&gt;{{cite web | title = Canine Distemper: What You Need To Know | work = Veterinary Insider | url = http://www.veterinaryinsider.com/public/Canine-Distemper-What-You-Need-To-Know.cfm | access-date = 2012-04-09 | url-status = dead | archive-url = https://web.archive.org/web/20120502040331/http://www.veterinaryinsider.com/public/Canine-Distemper-What-You-Need-To-Know.cfm | archive-date = 2012-05-02 | date = 2010-12-06 }}&lt;/ref&gt;[[File:Arctic-Lineage-Canine-Distemper-Virus-as-a-Cause-of-Death-in-Apennine-Wolves-(Canis-lupus)-in-Italy-pone.0082356.s001.ogv|thumb|[[Italian wolf]] in advanced stage of infection.]]

Life-threatening complications can include nervous-system degeneration. Dogs that have been infected with distemper can have a progressive deterioration of mental abilities and motor skills. With time, the dog can develop seizures, paralysis, a reduction in sight, and incoordination. These dogs are usually humanely euthanized because of the immense pain and suffering they face.&lt;ref name=Insider2012 /&gt;

==Virology==
[[File:Phylogenetic tree of Paramixoviruses with CDV.tif|thumb|Canine distemper virus position in the phylogenetic tree of Paramyxoviruses|upright]]
Distemper is caused by a single-stranded [[RNA virus]] of the family ''[[Paramyxoviridae]]'', and is a very close relative of the viruses of the same genus that cause [[measles]] in humans and [[rinderpest]] in animals.&lt;ref name=&quot;CreevyMerck&quot;&gt;Kate E. Creevy, 2013, ''Overview of Canine Distemper'', in ''The Merck Veterinary Manual'' (online): &quot;Veterinary Professionals: Generalized Conditions: Canine Distemper&quot;, see {{cite web |url=http://www.merckmanuals.com/vet/generalized_conditions/canine_distemper/overview_of_canine_distemper.html |title=Canine Distemper Overview – Generalized Conditions |access-date=2014-12-15 |url-status=live |archive-url=https://web.archive.org/web/20141223064911/http://www.merckmanuals.com/vet/generalized_conditions/canine_distemper/overview_of_canine_distemper.html |archive-date=2014-12-23 }}, accessed 15 December 2014.&lt;/ref&gt;&lt;ref name=McCarthy2007&gt;{{cite journal |vauthors=McCarthy AJ, Shaw MA, Goodman SJ |title=Pathogen evolution and disease emergence in carnivores |journal=Proc. Biol. Sci. |volume=274 |issue=1629 |pages=3165–3174 |date=December 2007 |pmid=17956850 |doi=10.1098/rspb.2007.0884 |pmc=2293938}}&lt;/ref&gt;

===Genetic diversity===
Geographically distinct lineages of the canine distemper virus are genetically diverse.  This diversity arises from [[mutation]] and, when two genetically distinct viruses infect the same cell, from [[homologous recombination]].&lt;ref&gt;{{cite journal | last1 = Yuan | first1 = C | last2 = Liu | first2 = W | last3 = Wang | first3 = Y | last4 = Hou | first4 = J | last5 = Zhang | first5 = L | last6 = Wang | first6 = G | year = 2017 | title = Homologous recombination is a force in the evolution of canine distemper virus | journal = PLOS ONE | volume = 12 | issue = 4| article-number = e0175416 | doi = 10.1371/journal.pone.0175416 | pmid = 28394936 | pmc = 5386261 | doi-access = free }}&lt;/ref&gt;

===Host range===
Distemper, or hardpad disease in canines,&lt;ref name=&quot;RadostitsEtalMerck&quot;&gt;Otto M. Radostits, David A. Ashford, Craig E. Greene, Ian Tizard, et al., 2011, ''Canine Distemper (Hardpad Disease)'', in The Merck Manual for Pet Health (online): Pet Owners: Dog Disorders and Diseases: Disorders Affecting Multiple Body Systems of Dogs, see {{cite web |url=http://www.merckmanuals.com/pethealth/dog_disorders_and_diseases/disorders_affecting_multiple_body_systems_of_dogs/canine_distemper_hardpad_disease.html |title=Canine Distemper (Hardpad Disease) – Dog Owners |access-date=2014-12-15 |url-status=live |archive-url=https://web.archive.org/web/20141216005330/http://www.merckmanuals.com/pethealth/dog_disorders_and_diseases/disorders_affecting_multiple_body_systems_of_dogs/canine_distemper_hardpad_disease.html |archive-date=2014-12-16 }}, accessed 15 December 2014.&lt;/ref&gt; affects animals in the following families and species:

* [[Ailuridae]] (red panda)
* [[Canidae]] (dog, fox, wolf, [[raccoon dog|Chinese raccoon dog]])
* [[Elephantidae]] ([[Asian elephant]])
* [[Felidae]] (large cats,&lt;ref name=CreevyMerck/&gt; though not [[cat|domestic cats]])
* [[Hyaenidae]] (hyena)
* [[Mustelidae]] (ferret, mink, skunk, wolverine, marten, badger, otter)&lt;ref name=CreevyMerck/&gt;&lt;ref name=RadostitsEtalMerck/&gt;
* [[Pinnipedia]] (seals, walrus, sea lion, etc.)&lt;ref&gt;Kennedy, Seamus, et al. &quot;[https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2640919/pdf/11076723.pdf Mass die-off of Caspian seals caused by canine distemper virus].&quot; Emerging infectious diseases 6.6 (2000): 637.&lt;/ref&gt;&lt;ref name=Jones1997/&gt;
* [[Primate]] (some; e.g. Japanese macaque, but not humans)&lt;ref name=CreevyMerck/&gt;
* [[Procyonidae]] (raccoon, coati)
* [[Ursidae]] (bear)
* [[Viverridae]] (raccoon-like South Asian binturong, palm civet)&lt;ref name=CreevyMerck/&gt;

Animals in the family Felidae, including many species of large cat as well as domestic cats, were long believed to be resistant to canine distemper until some researchers reported the prevalence of canine distemper virus (CDV) infection in large felids.&lt;ref name=Ikeda2001&gt;{{cite journal |last1=Ikeda |first1=Yasuhiro |last2=Nakamura |first2=Kazuya |last3=Miyazawa |first3=Takayuki |last4=Chen |first4=Ming-Chu |last5=Kuo |first5=Tzong-Fu |last6=Lin |first6=James A |last7=Mikami |first7=Takeshi |last8=Kai |first8=Chieko |last9=Takahashi |first9=Eiji |title=Seroprevalence of Canine Distemper Virus in Cats |journal=Clin Vaccine Immunol |date=May 2001 |volume=8 |issue=3 |pages=641–644 |doi=10.1128/CDLI.8.3.641-644.2001 |pmid=11329473 |pmc=96116 }}&lt;/ref&gt; Both large and domestic cats are now known to be capable of infection, usually through close housing with dogs &lt;ref name=Ikeda2001/&gt;&lt;ref name=GreeneAppel2006&gt;{{cite book|author1=Greene, Craig E |author2=Appel, Max J|editor1-last=Greene|editor1-first=Craig E|title=Infectious Diseases of the Dog and Cat |date=2006 |publisher=Elsevier |location=St Louis, MO |isbn=978-1-4160-3600-5|edition=3rd|chapter=3. Canine distemper}}&lt;/ref&gt; or possibly blood transfusion from infected cats,&lt;ref name=Ikeda2001/&gt; but such infections appear to be self-limiting and largely without symptoms.&lt;ref name=GreeneAppel2006/&gt;

In a captive population of [[giant pandas]] in China (Shanxi Rare Wild Animal Rescue and Research Center), six of 22 captive pandas were infected by CDV.  All but one infected panda died; the survivor had previously been vaccinated.&lt;ref&gt;{{cite journal|title=Fatal canine distemper virus infection of giant pandas in China|first1=Na|last1=Feng|first2=Yicong|last2=Yu|first3=Tiecheng|last3=Wang|first4=Peter|last4=Wilker|first5=Jianzhong|last5=Wang|first6=Yuanguo|last6=Li|first7=Zhe|last7=Sun|first8=Yuwei|last8=Gao|first9=Xianzhu|last9=Xia|date=16 June 2016|journal=Scientific Reports|volume=6|issue=1|article-number=27518|doi=10.1038/srep27518|pmid=27310722|pmc=4910525|bibcode=2016NatSR...627518F}}&lt;/ref&gt;

==Mechanism==
[[File:12985 2019 1136 Fig4 HTML.webp|alt=|thumb|Principal routes of canine distemper virus (CDV) infection and transmission in hosts]]

The canine distemper virus affects nearly all body systems.&lt;ref name=&quot;Beineke 2015&quot;&gt;{{cite journal|last1=Beineke|first1=A|last2=Baumgärtner|first2=W|last3=Wohlsein|first3=P|title=Cross-species transmission of canine distemper virus-an update|journal=One Health|date=December 2015|volume=1|pages=49–59|doi=10.1016/j.onehlt.2015.09.002|pmid=28616465|pmc=5462633}}&lt;/ref&gt; Puppies from 3–6 months old are particularly susceptible.&lt;ref name=&quot;remedys&quot;&gt;{{cite web|url=http://www.healthcommunities.com/canine-distemper/canine-distemper-overview.shtml|title=Health Topics: Pet Health: Canine Distemper: Canine Distemper Overview|date=4 Nov 2014|website=HealthCommunities.com|orig-year=28 Feb 2001|url-status=live|archive-url=https://web.archive.org/web/20141220224421/http://www.healthcommunities.com/canine-distemper/canine-distemper-overview.shtml|archive-date=2014-12-20|access-date=2014-12-15}}, accessed 15 December 2014.&lt;/ref&gt; CDV spreads through aerosol droplets and through contact with infected bodily fluids, including nasal and ocular secretions, [[feces]], and [[urine]], 6 to 22 days after exposure. It can also be spread by food and water contaminated with these fluids.&lt;ref name=&quot;Carter&quot;&gt;{{cite web|url=http://www.ivis.org/advances/Carter/Part2Chap18/chapter.asp?LA=1|title=Paramyxoviridae|author1=Carter, G.R.|author2=Flores, E.F.|year=2006|work=A Concise Review of Veterinary Virology|access-date=2006-06-24|author3=Wise, D.J.}}&lt;/ref&gt;&lt;ref name=&quot;Hirsch1999&quot;&gt;{{cite book|title=Veterinary Microbiology|author=Hirsch, D.C.|author2=Zee, C.|publisher=Blackwell Publishing|year=1999|display-authors=etal}}&lt;/ref&gt; The time between infection and disease is 14 to 18 days, although a fever can appear from 3 to 6 days after infection.&lt;ref name=&quot;Carmichael&quot;&gt;{{cite web|url=http://www.ivis.org/advances/Infect_Dis_Carmichael/appel/chapter_frm.asp?LA=1|title=Canine Distemper: Current Status|author1=Appel, M.J.G.|author2=Summers, B.A.|year=1999|work=Recent Advances in Canine Infectious Diseases|url-status=live|archive-url=https://web.archive.org/web/20050901104919/http://www.ivis.org/advances/Infect_Dis_Carmichael/appel/chapter_frm.asp?LA=1|archive-date=2005-09-01|access-date=2006-06-24}}&lt;/ref&gt;

The canine distemper virus tends to direct its infection toward the [[lymphatic system|lymphoid]], [[epithelium|epithelial]], and [[nervous system|nervous tissues]]. The virus initially replicates in the lymphatic tissue of the respiratory tract.  The virus then enters the blood stream and infects the [[respiratory]], [[gastrointestinal]], [[urogenital]], epithelial, and [[central nervous system]]s, as well as [[optic nerve]]s.&lt;ref name=&quot;CreevyMerck&quot; /&gt; Therefore, the typical pathologic features of canine distemper include lymphoid depletion (causing [[immunosuppression]] and leading to secondary infections), interstitial [[pneumonia]], [[encephalitis]] with [[demyelination]], and [[hyperkeratosis]] of the nose and foot pads.

The virus first appears in bronchial lymph nodes and tonsils two days after exposure.  The virus then enters the bloodstream on the second or third day.&lt;ref name=&quot;Hirsch1999&quot;/&gt;  A first round of acute fever tends to begin around 3–8 days after infection, which is often accompanied by a low white blood cell count, especially of [[lymphocytes]], as well as a low platelet count.  These signs may or may not be accompanied by [[Anorexia (symptom)|anorexia]], a runny nose, or discharge from the eye.  This first round of fever typically recedes rapidly within 96 hours, and then a second round of fever begins around the 11th or 12th day and lasts at least a week.  Gastrointestinal and respiratory problems tend to follow, which may become complicated with secondary bacterial infections.  Inflammation of the brain and spinal cord, otherwise known as [[encephalomyelitis]], either is associated with this, subsequently follows, or comes completely independently of these problems. A thickening of the footpads sometimes develops, and vesicular pustular lesions on the abdomen usually develop. Neurological signs are typically found in animals with thickened footpads from the virus.&lt;ref name=CreevyMerck/&gt;&lt;ref name=&quot;Jones1997&quot;/&gt; About half of sufferers&lt;!-- !  check for tone !--&gt; experience [[meningoencephalitis]].&lt;ref name=&quot;Jones1997&quot;/&gt; Less than 50% of the adult dogs that contract the disease die from it. Among puppies, the death rate often reaches 80%.&lt;ref&gt;{{cite web|url=https://acadogs.com/Canine_Distemper.html |title=Canine Distemper |publisher=American Canine Association, Inc.|access-date=2015-04-13 |url-status=dead |archive-url=https://web.archive.org/web/20150202193246/https://acadogs.com/Canine_Distemper.html |archive-date=2015-02-02 }}&lt;/ref&gt;

==Diagnosis==
[[File:Canine distemper pathology.jpg|thumb|upright|A. Lung lesion in an [[African wild dog]] B. [[Viroplasm|Viral inclusion bodies]]]]

The above signs, especially fever, respiratory signs, neurological signs, and thickened footpads, occurring in unvaccinated dogs strongly indicate CDV.  However, several febrile diseases match many of the signs of the disease and only recently has distinguishing between canine [[hepatitis]], [[herpes]] virus, [[parainfluenza]], and [[leptospirosis]] been possible.&lt;ref name=&quot;Jones1997&quot;/&gt;  Thus, finding the virus by various methods in the dog's conjunctival cells or foot pads gives a definitive diagnosis.  In older dogs that develop distemper encephalomyelitis, diagnosis may be more difficult, since many of these dogs have an adequate vaccination history.&lt;ref name=&quot;Dewey2003&quot;/&gt;

An additional test to confirm distemper is a [[brush border]] slide of the bladder transitional epithelium of the inside lining from the bladder, stained with [[Diff-Quik]]. These infected cells have inclusions which stain a carmine red color, found in the [[Cell nucleus|paranuclear]] [[cytoplasm]]. About 90% of the bladder cells will be positive for inclusions in the early stages of distemper.&lt;ref&gt;{{cite web|url=http://www.kindheartsinaction.com/archives/82|title=NDV-Induced Serum|publisher=Kind Hearts in Action|date=November 5, 2009|access-date=October 31, 2012|url-status=live|archive-url=https://web.archive.org/web/20120625140347/http://www.kindheartsinaction.com/archives/82|archive-date=June 25, 2012}}&lt;/ref&gt;

==Prevention==
{{See also|DA2PPC Vaccine}}

A number of [[vaccine]]s against CDV exist for [[dog]]s ([[ATCvet]] code: {{ATCvet|I07|AD05}} and combinations) and [[ferret|domestic ferrets]] ({{ATCvet|I20|DD01}}), which in many jurisdictions are mandatory for pets. Infected animals should be [[quarantine]]d from other dogs for several months owing to the length of time the animal may shed the virus.&lt;ref name=CreevyMerck/&gt; The virus is destroyed in the environment by routine cleaning with disinfectants, detergents, or drying. It does not survive in the environment for more than a few hours at room temperature (20–25&amp;nbsp;°C), but can survive for a few weeks in shady environments at temperatures slightly above freezing.&lt;ref name=&quot;Davis Koret&quot;&gt;{{cite web | title=Canine Distemper (CDV) | work=UC Davis Koret Shelter Medicine Program | year=2004 | url=http://www.sheltermedicine.com/library/canine-distemper-cdv | access-date=2013-08-17 | url-status=dead | archive-url=https://web.archive.org/web/20151010083042/http://www.sheltermedicine.com/library/canine-distemper-cdv | archive-date=2015-10-10 }}&lt;/ref&gt; It, along with other labile viruses, can also persist longer in serum and tissue debris.&lt;ref name=&quot;Hirsch1999&quot;/&gt;

Despite extensive vaccination in many regions, it remains a major disease of dogs.

To prevent canine distemper, puppies should begin vaccination at 6–8 weeks of age and then continue getting the &quot;booster shot&quot; every 2–4 weeks until they are 16 weeks of age. Without the full series of shots, the vaccination does not provide protection against the virus. Since puppies are typically sold at the age of 8–10 weeks, they typically receive the first shot while still with their breeder, but the new owner often does not finish the series. These dogs are not protected against the virus, so are susceptible to canine distemper infection, continuing the downward spiral that leads to outbreaks throughout the world.&lt;ref name=&quot;Canine Distemper: Prevention of Infections&quot;&gt;{{cite web | title = Canine Distemper: Prevention of Infections | work = MarvistaVet | url = http://www.marvistavet.com/html/body_canine_distemper.html | access-date = 2012-04-09 | url-status = dead | archive-url = https://web.archive.org/web/20120421215914/http://www.marvistavet.com/html/body_canine_distemper.html | archive-date = 2012-04-21 }}&lt;/ref&gt;

==Treatment==
No specific treatment for the CDV is known. As with measles, the treatment is symptomatic and supportive.&lt;ref name=CreevyMerck/&gt; Care is geared towards treating fluid/electrolyte imbalances, neurological symptoms, and preventing any secondary bacterial infections. Examples include administering fluids, electrolyte solutions, analgesics, anticonvulsants, broad-spectrum antibiotics, antipyretics, parenteral nutrition, and nursing care.&lt;ref&gt;{{Cite web|title = Overview of Canine Distemper: Canine Distemper: Merck Veterinary Manual|url = http://www.merckvetmanual.com/mvm/generalized_conditions/canine_distemper/overview_of_canine_distemper.html?qt=canine%2520distemper%2520virus&amp;alt=sh|website = www.merckvetmanual.com|access-date = 2016-02-13|publisher = Merck Sharp &amp; Dohme Corp|year = 2009|location = Kenilworth, NJ|url-status = live|archive-url = https://web.archive.org/web/20161005115026/http://www.merckvetmanual.com/mvm/generalized_conditions/canine_distemper/overview_of_canine_distemper.html?qt=canine%2520distemper%2520virus&amp;alt=sh|archive-date = 2016-10-05}}&lt;/ref&gt;

==Outcome==
The mortality rate of CDV largely depends on the immune status of the infected dogs. Puppies experience the highest mortality rate, where complications such as [[pneumonia]] and [[encephalitis]] are more common.&lt;ref name=&quot;Hirsch1999&quot;/&gt;  In older dogs that develop distemper, [[encephalomyelitis]] and [[vestibular disease]] may be present.&lt;ref name=&quot;Dewey2003&quot;&gt;{{cite book|title=A Practical Guide to Canine and Feline Neurology|author=Dewey, C.W.|publisher=Iowa State Pr|year=2003}}&lt;/ref&gt; Around 15% of canine inflammatory central nervous system diseases are a result of CDV.&lt;ref name=&quot;Elia2008&quot;&gt;{{cite journal|display-authors=etal|vauthors=Elia G, Belloli C, Cirone F|date=February 2008|title=In vitro efficacy of ribavirin against canine distemper virus|journal=Antiviral Res.|volume=77|issue=2|pages=108–113|doi=10.1016/j.antiviral.2007.09.004|pmid=17949825}}&lt;/ref&gt;

==Epidemiology==
The prevalence of canine distemper in the community has decreased dramatically due to the availability of vaccinations. However, the disease continues to spread among unvaccinated populations, such as those in animal shelters and pet stores. This provides a great threat to both the rural and urban communities throughout the United States, affecting both shelter and domestic canines. Despite the effectiveness of the vaccination, outbreaks of this disease continue to occur nationally. In April 2011, the Arizona Humane Society released a valley-wide pet health alert throughout Phoenix, Arizona.&lt;ref&gt;{{cite web|title=AHS ISSUES VALLEYWIDE PET HEALTH ALERT|work=Arizona Humane Society|url=http://www.azhumane.org/artman2/publish/aboutus/PET_HEALTH_ALERT.shtml|access-date=2012-04-09|archive-url=https://web.archive.org/web/20120415215710/http://www.azhumane.org/artman2/publish/aboutus/PET_HEALTH_ALERT.shtml|archive-date=2012-04-15|url-status=dead}}&lt;/ref&gt;

Outbreaks of canine distemper continue to occur throughout the United States and elsewhere and are caused by many factors, including proximity to wild animals and lack of vaccinated animals. This problem is even greater within areas such as Arizona, owing to the vast amount of rural land. An unaccountable number of strays that lack vaccinations reside in these areas, so they are more susceptible to diseases such as canine distemper. These strays act as a reservoir for the virus, spreading it throughout the surrounding area, including urban areas. Puppies and dogs that have not received their shots can then be infected in a place where many dogs interact, such as a dog park.

==References==
{{Reflist|2}}

==Further reading==
* {{Cite journal |last1=Di Sabatino |first1=D |last2=Lorusso |first2=A |last3=Di Francesco |first3=CE |last4=Gentile |first4=L |last5=Di Pirro |first5=V |last6=Bellacicco |first6=AL |last7=Giovannini |first7=A |last8=Di Francesco |first8=G |last9=Marruchella |first9=G |last10=Marsilio |first10=F |last11=Savini |first11=G |date=Jan 2014 |title=Arctic Lineage-Canine Distemper Virus as a Cause of Death in Apennine Wolves (''Canis Lupus'') in Italy |journal=[[PLoS One]] |volume=9 |issue=1|article-number=e82356 |doi=10.1371/journal.pone.0082356 |pmid=24465373 |pmc=3896332 |bibcode=2014PLoSO...982356D |doi-access=free}}

== External links ==
* {{Commons category-inline|Canine distemper}}

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{{DEFAULTSORT:Canine distemper}}
[[Category:Animal viral diseases]]
[[Category:Carnivoran diseases]]
[[Category:Dog diseases|Distemper]]
[[Category:Paramyxoviridae]]
[[Category:Vaccine-preventable diseases]]