Todayโs path rounds are on ๐๐๐ง๐ข๐ง๐ ๐ข๐ง๐๐๐๐ญ๐ข๐จ๐ฎ๐ฌ ๐ก๐๐ฉ๐๐ญ๐ข๐ญ๐ข๐ฌ!
๐๐ก๐๐ญ ๐ข๐ฌ ๐ข๐ญ?
๐๐๐ง๐ข๐ง๐ ๐ข๐ง๐๐๐๐ญ๐ข๐จ๐ฎ๐ฌ ๐ก๐๐ฉ๐๐ญ๐ข๐ญ๐ข๐ฌ is a viral disease caused by ๐๐๐ง๐ข๐ง๐ ๐๐๐๐ง๐จ๐ฏ๐ข๐ซ๐ฎ๐ฌ, one of the major pathogens we vaccinate dogs for! In fact, our vaccination policies have been so successful that this disease is now considered rare in North America.
๐๐ก๐จ ๐ ๐๐ญ๐ฌ ๐ข๐ญ?
This disease primarily affects young puppies, although any dog can get it. In general, dogs over 2 years of age are less likely to have severe disease.
๐๐ก๐๐ญ ๐๐๐ฎ๐ฌ๐๐ฌ ๐ข๐ญ?
As mentioned, this disease is caused by an adenovirus. Dogs acquire the virus through ๐ข๐ง๐ก๐๐ฅ๐๐ญ๐ข๐จ๐ง or ๐ข๐ง๐ ๐๐ฌ๐ญ๐ข๐จ๐ง, allowing the virus to come into contact with the tonsils and ๐๐๐ฒ๐๐ซ’๐ฌ ๐ฉ๐๐ญ๐๐ก๐๐ฌ, which are lymph node-like structures in the intestine. In these locations, the virus replicates and enters the bloodstream, where it seeks out ๐๐ง๐๐จ๐ญ๐ก๐๐ฅ๐ข๐ฎ๐ฆ, the cells lining blood vessels. Because blood vessels can be found pretty much everywhere, we can see the virus in numerous organs, including the liver, kidneys, spleen and lungs.
๐๐ก๐ฒ ๐ข๐ฌ ๐ญ๐ก๐ข๐ฌ ๐ ๐ฉ๐ซ๐จ๐๐ฅ๐๐ฆ?
Once the virus infects the endothelium, it damages the cells. This allows blood, fluid and proteins to leak out of the vessels into the surrounding areas, which we see as hemorrhage and edema. As you might have guessed from the name infectious canine hepatitis, this virus also has a particular ๐ญ๐ซ๐จ๐ฉ๐ข๐ฌ๐ฆ (affinity) for the cells of the liver. When it infects these cells, it causes ๐ง๐๐๐ซ๐จ๐ฌ๐ข๐ฌ (cell death), which can affect liver function. Clinically, these animals present with ๐ฉ๐๐ญ๐๐๐ก๐ข๐๐ (small hemorrhages) on their mucosa, edema under the skin, abdominal pain, fever and vomiting.
Another interesting problem that develops from canine adenovirus infection is formation of ๐ข๐ฆ๐ฆ๐ฎ๐ง๐ ๐๐จ๐ฆ๐ฉ๐ฅ๐๐ฑ๐๐ฌ. These complexes occur when an antibody binds to the virus, and forms a large structure that the body cannot easily remove. These complexes tend to lodge in vessels and cause a local inflammatory reaction. One common site for these complexes to lodge is the ๐๐จ๐ซ๐ง๐๐ (outer aspect of the eye), causing edema. Clinically, this looks like the eyes turning blue or cloudy, as the extra fluid builds up within the eye! Wild.
๐๐จ๐ฐ ๐ข๐ฌ ๐ข๐ญ ๐๐ข๐๐ ๐ง๐จ๐ฌ๐๐?
Diagnosis can be made through ๐๐๐ ๐ญ๐๐ฌ๐ญ๐ข๐ง๐ , where the DNA of the virus is directly identified. At necropsy, adenovirus causes ๐ข๐ง๐ญ๐ซ๐๐ง๐ฎ๐๐ฅ๐๐๐ซ ๐ข๐ง๐๐ฅ๐ฎ๐ฌ๐ข๐จ๐ง ๐๐จ๐๐ข๐๐ฌ (pink dots within the nucleus) that can be used to support diagnosis of the disease.
๐๐จ๐ฐ ๐ข๐ฌ ๐ข๐ญ ๐ญ๐ซ๐๐๐ญ๐๐? ๐๐จ๐ฐ ๐ข๐ฌ ๐ข๐ญ ๐ฉ๐ซ๐๐ฏ๐๐ง๐ญ๐๐?
Unfortunately, this disease has a very poor prognosis in young puppies, with a mortality rate of 10-30%. Treatment typically involves supportive care to help the body fight the infection, as there is no specific treatment available. Thankfully, we now have very effective vaccines against this disease!
๐๐ก๐จ๐ญ๐จ๐ฌ
1-3) A liver, kidney and lungs with multiple small hemorrhages from canine adenovirus.
4) A puppy with โblue eyeโ.
5) Intranuclear inclusions in the liver!
๐๐จ๐ฎ๐ซ๐๐๐ฌ
Maxie, G. Jubb, Kennedy and Palmerโs Pathology of Domestic Animals, Volume 2. Sixth Edition.
Creevy KE. Overview of infectious canine hepatitis. Merck Veterinary Manual 2016.
Photos 1-4 ยฉ Noahโs Arkive contributors Read, Williams, Kesdangsakonwut, Jakowski licensed under CC BY-SA 4.0.
Photo 5 ยฉ University of Calgary Diagnostic Services Unit.
