Canine Distemper

Itโ€™s New Yearโ€™s Eve! 2022 is the year of the tiger in the Chinese zodiac, so I thought talking about tigers today would be fun. Todayโ€™s path rounds are on ๐œ๐š๐ง๐ข๐ง๐ž ๐๐ข๐ฌ๐ญ๐ž๐ฆ๐ฉ๐ž๐ซ!

๐–๐ก๐š๐ญ ๐ข๐ฌ ๐ข๐ญ?
๐‚๐š๐ง๐ข๐ง๐ž ๐๐ข๐ฌ๐ญ๐ž๐ฆ๐ฉ๐ž๐ซ is a ๐Œ๐จ๐ซ๐›๐ข๐ฅ๐ฅ๐ข๐ฏ๐ข๐ซ๐ฎ๐ฌ that was first described in dogs, hence the name. However, we have since learned that this virus can infect multiple species of carnivores, including the large cats.

๐–๐ก๐จ ๐ ๐ž๐ญ๐ฌ ๐ข๐ญ?
Outbreaks of canine distemper have been reported in all five of the ๐๐š๐ง๐ญ๐ก๐ž๐ซ๐š species, including tigers.

๐–๐ก๐š๐ญ ๐œ๐š๐ฎ๐ฌ๐ž๐ฌ ๐ข๐ญ?
This virus is transmitted by close contact with an infected individual, or aerosolized droplets. Once inhaled, the virus sets up shop n the tonsils and undergoes replication. From there, it gains access to the bloodstream.

The virusโ€™ favourite blood cells are the ๐ฅ๐ž๐ฎ๐ค๐จ๐œ๐ฒ๐ญ๐ž๐ฌ (white blood cells). The virus will invade these cells and destroy them, resulting ๐ฅ๐ž๐ฎ๐ค๐จ๐ฉ๐ž๐ง๐ข๐š (low white blood cells). Because the white blood cells are the major players in the immune system, this ultimately results in ๐ข๐ฆ๐ฆ๐ฎ๐ง๐จ๐ฌ๐ฎ๐ฉ๐ฉ๐ซ๐ž๐ฌ๐ฌ๐ข๐จ๐ง for the tiger.

The virus can also use the bloodstream to gain access to the gastrointestinal and respiratory tracts, where it can cause diarrhea, nasal discharge and difficulty breathing. In some cases, it can also gain access to the brain, causing inflammation and ๐ง๐ž๐ฎ๐ซ๐จ๐ฅ๐จ๐ ๐ข๐œ๐š๐ฅ ๐ฌ๐ข๐ ๐ง๐ฌ like falling over, depression, blindness and seizures. Once neurologic signs develop, the disease is almost entirely fatal.

๐–๐ก๐ฒ ๐ข๐ฌ ๐ญ๐ก๐ข๐ฌ ๐š ๐ฉ๐ซ๐จ๐›๐ฅ๐ž๐ฆ?
Unfortunately, tigers are already considered to be endangered, and having a fatal disease in the population certainly doesnโ€™t help their situation! It has been estimated that the presence of canine distemper in a small group of tigers is 65% more likely to cause extinction in that group over a 50 year period. With only ๐Ÿ‘๐Ÿ—๐ŸŽ๐ŸŽ tigers left in the wild, often living in small groups, this disease is certainly a huge concern!

๐‡๐จ๐ฐ ๐ข๐ฌ ๐ข๐ญ ๐ญ๐ซ๐ž๐š๐ญ๐ž๐? ๐‡๐จ๐ฐ ๐ข๐ฌ ๐ข๐ญ ๐ฉ๐ซ๐ž๐ฏ๐ž๐ง๐ญ๐ž๐?
Unfortunately there is no specific treatment for this virus, other than supportive care to help ensure the animal is comfortable. Thus, prevention is key for managing this disease. Currently, scientists are putting effort into developing a vaccine that can be used in wild tigers, as we already have effective annual vaccines for this disease used in dogs. Other ideas for prevention include preventing tiger exposure to wild and domestic dogs, although this is proving to be quite difficult!

๐๐ก๐จ๐ญ๐จ๐ฌ
1-2) Examples of the pneumonia that distemper can cause (these photos are from dogs).
3) Canine distemper ๐ข๐ง๐œ๐ฅ๐ฎ๐ฌ๐ข๐จ๐ง ๐›๐จ๐๐ข๐ž๐ฌ in ๐ง๐ž๐ฎ๐ญ๐ซ๐จ๐ฉ๐ก๐ข๐ฅ๐ฌ (a major clean up cell) and red blood cells. Inclusion bodies are the virus itself, along with all of the proteins it is producing. Proteins stain pink, giving the inclusion bodies their rosy complexion ๐Ÿ˜‚
4) A neuron containing a large inclusion body!
5-6) I Spy time! Can you find the inclusion bodies in these photos?

๐’๐จ๐ฎ๐ซ๐œ๐ž๐ฌ
Disease Threat: Canine Distemper Virus (CDV). Wild Tiger Health Center.
Gilbert M, Miquelle DG, Goodrich JM et al. Estimating the Potential Impact of Canine Distemper Virus on the Amur Tiger Population (Panthera tigris altaica) in Russia. PLOS One 2014; 9(10).

Photos 1-6 ยฉ Noahโ€™s Arkive contributor Naranjo, Peterson, King, Latimer, McGavin licensed under CC BY-SA 4.0.

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