Todayโs path rounds are on ๐๐จ๐ง๐ ๐๐ง๐ข๐ญ๐๐ฅ ๐ฉ๐จ๐ซ๐ฉ๐ก๐ฒ๐ซ๐ข๐! This post is inspired by a recent post by @clinpathkate on Instagram. It has some great images so go check it out!
๐๐ก๐๐ญ ๐ข๐ฌ ๐ข๐ญ?
๐๐จ๐ง๐ ๐๐ง๐ข๐ญ๐๐ฅ ๐ฉ๐จ๐ซ๐ฉ๐ก๐ฒ๐ซ๐ข๐ is a red to brown discolouration of the bones and teeth, starting from birth, due to the accumulation of ๐ฉ๐จ๐ซ๐ฉ๐ก๐ฒ๐ซ๐ข๐ง๐ฌ (compounds that bind metals, such as heme in red blood cells). The name porphyrin derives from the Greek word prophyra, which means purple, and tells you a bit about what colour these compounds are!
๐๐ก๐จ ๐ ๐๐ญ๐ฌ ๐ข๐ญ?
This condition has primarily been described in several breeds of cattle, but there have also been numerous reports of the condition in cats!
๐๐ก๐๐ญ ๐๐๐ฎ๐ฌ๐๐ฌ ๐ข๐ญ?
Most cases of porphyria are congenital, and are caused by a genetic deficiency in the enzyme ๐ฎ๐ซ๐จ๐ฉ๐จ๐ซ๐ฉ๐ก๐ฒ๐ซ๐ข๐ง ๐๐๐ ๐๐จ๐ฌ๐ฒ๐ง๐ญ๐ก๐๐ญ๐๐ฌ๐. This enzyme is part of the heme production pathway, which is made up of different steps of porphyrin processing until it eventually becomes heme. Without this enzyme, one of the steps stops completely, and the porphyrins begin to accumulate in the body. They tend to accumulate in the teeth, bones and urine, producing the reddish-brown tinge.
๐๐ก๐ฒ ๐ข๐ฌ ๐ญ๐ก๐ข๐ฌ ๐ ๐ฉ๐ซ๐จ๐๐ฅ๐๐ฆ?
In general, this condition isnโt a huge issue for the animal, and they can live a pretty happy life. However, there are a few unique issues with having a lot of porphyrins floating around!
The first issue is ๐ฉ๐ก๐จ๐ญ๐จ๐ฌ๐๐ง๐ฌ๐ข๐ญ๐ข๐ณ๐๐ญ๐ข๐จ๐ง, or skin that is easily damaged by sunlight. This happens because porphyrins in the skin react with the UV light from the sun, and can cause local damage to tissues. So these critters should be kept out of the sun as much as possible!
The second potential issue is ๐ก๐๐ฆ๐จ๐ฅ๐ฒ๐ญ๐ข๐ ๐๐ง๐๐ฆ๐ข๐, aka destruction of red blood cells. Porphyrin accumulation in red blood cells is directly toxic to them, which can cause their destruction. This can have a whole host of side effects, and generally has a poor prognosis attached to it.
๐๐จ๐ฐ ๐ข๐ฌ ๐ข๐ญ ๐๐ข๐๐ ๐ง๐จ๐ฌ๐๐?
The best way to diagnose this condition is UV light! When exposed to a black light, the bones will glow pink due to the interactions of the purpley porphyrins and the UV light. Crazy!
๐๐ก๐จ๐ญ๐จ๐ฌ
1) Comparison of the femur of a cat with congenital porphyria (top) to a normal cat femur.
2-3) A femur with congenital porphyria under normal light and UV light!
4-5) More examples of pink bones!
๐๐จ๐ฎ๐ซ๐๐๐ฌ
Maxie, G. Jubb, Kennedy and Palmerโs Pathology of Domestic Animals, Volume 1. Sixth Edition.
Photos 1-5 courtesy of Noahโs Arkive.
