Itโs New Yearโs Eve! 2022 is the year of the tiger in the Chinese zodiac, so I thought talking about tigers today would be fun. Todayโs path rounds are on ๐๐๐ง๐ข๐ง๐ ๐๐ข๐ฌ๐ญ๐๐ฆ๐ฉ๐๐ซ!
๐๐ก๐๐ญ ๐ข๐ฌ ๐ข๐ญ?
๐๐๐ง๐ข๐ง๐ ๐๐ข๐ฌ๐ญ๐๐ฆ๐ฉ๐๐ซ is a ๐๐จ๐ซ๐๐ข๐ฅ๐ฅ๐ข๐ฏ๐ข๐ซ๐ฎ๐ฌ 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.
๐๐ก๐จ ๐ ๐๐ญ๐ฌ ๐ข๐ญ?
Outbreaks of canine distemper have been reported in all five of the ๐๐๐ง๐ญ๐ก๐๐ซ๐ species, including tigers.
๐๐ก๐๐ญ ๐๐๐ฎ๐ฌ๐๐ฌ ๐ข๐ญ?
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 ๐ฅ๐๐ฎ๐ค๐จ๐๐ฒ๐ญ๐๐ฌ (white blood cells). The virus will invade these cells and destroy them, resulting ๐ฅ๐๐ฎ๐ค๐จ๐ฉ๐๐ง๐ข๐ (low white blood cells). Because the white blood cells are the major players in the immune system, this ultimately results in ๐ข๐ฆ๐ฆ๐ฎ๐ง๐จ๐ฌ๐ฎ๐ฉ๐ฉ๐ซ๐๐ฌ๐ฌ๐ข๐จ๐ง 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 ๐ง๐๐ฎ๐ซ๐จ๐ฅ๐จ๐ ๐ข๐๐๐ฅ ๐ฌ๐ข๐ ๐ง๐ฌ like falling over, depression, blindness and seizures. Once neurologic signs develop, the disease is almost entirely fatal.
๐๐ก๐ฒ ๐ข๐ฌ ๐ญ๐ก๐ข๐ฌ ๐ ๐ฉ๐ซ๐จ๐๐ฅ๐๐ฆ?
Unfortunately, tigers are already considered to be endangered, and having a fatal disease in the population certainly doesnโt 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 ๐๐๐๐ tigers left in the wild, often living in small groups, this disease is certainly a huge concern!
๐๐จ๐ฐ ๐ข๐ฌ ๐ข๐ญ ๐ญ๐ซ๐๐๐ญ๐๐? ๐๐จ๐ฐ ๐ข๐ฌ ๐ข๐ญ ๐ฉ๐ซ๐๐ฏ๐๐ง๐ญ๐๐?
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!
๐๐ก๐จ๐ญ๐จ๐ฌ
1-2) Examples of the pneumonia that distemper can cause (these photos are from dogs).
3) Canine distemper ๐ข๐ง๐๐ฅ๐ฎ๐ฌ๐ข๐จ๐ง ๐๐จ๐๐ข๐๐ฌ in ๐ง๐๐ฎ๐ญ๐ซ๐จ๐ฉ๐ก๐ข๐ฅ๐ฌ (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 
4) A neuron containing a large inclusion body!
5-6) I Spy time! Can you find the inclusion bodies in these photos?
๐๐จ๐ฎ๐ซ๐๐๐ฌ
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 Noahโs Arkive contributor Naranjo, Peterson, King, Latimer, McGavin licensed under CC BY-SA 4.0.
