Inflammation of the hoof dermis - "Pododermatitis"

The hoof dermis is the "living" (blood-perfused) layer directly beneath the horn capsule. It is responsible for horn production and thus essentially connects the interior of the hoof with the horn capsule.

When the dermis becomes inflamed, it swells in the same way as other tissue types swell in an inflammatory reaction. However, because the hoof capsule is very rigid, the swelling presses on sensitive tissue and causes considerable pain. Depending on the cause and location of the inflammation of the hoof dermis, different diseases are distinguished.

Different types of inflammation of the hoof dermis

In the hoof there are various types of dermis and all of them can become inflamed: perioplic, bulb, sole, frog and wall dermis. The inflammation can either be locally restricted or diffuse (extensive).

In addition, inflammation of the hoof dermis can have various causes: it can either be caused by bacteria (= septic, purulent) or it can develop without the involvement of a pathogen (= aseptic, non-purulent).

Furthermore, inflammation of the hoof dermis can be either acute or chronic.

Depending on the combination of these factors, the following variants can be distinguished:

• septic inflammation of the hoof dermis: this is called abscess or hoof ulcer
• aseptic inflammation of the hoof dermis: here the following forms can be further distinguished:
• acute or chronic perioplic dermis inflammation (e.g. caused by irritating "care" substances)
• acute localised inflammation of the hoof dermis due to trauma (this includes "stone bruises")
• acute diffuse sole dermis inflammation (e.g. caused by overloading or overly invasive hoof trimming)
• by definition, laminitis is also one of the non-purulent inflammations of the hoof dermis - but attention: there are various causes of laminitis and the most common of them (a problem of the hormonal metabolism) is not accompanied by an inflammation of the dermis

The diagnosis "inflammation of the hoof dermis" is therefore very imprecise, because depending on the specific type the course of the disease and the treatment can be completely different. A hoof abscess must be treated quite differently from a perioplic dermis inflammation or a stone bruise.

When people commonly speak of "inflammation of the hoof dermis" without specifying it further, an aseptic (i.e. non-purulent) form is usually meant, namely either of the sole dermis or a locally restricted inflammation as a consequence of trauma. We therefore want to look at this form a little more closely.

Aseptic localised inflammation of the hoof dermis

A locally restricted, acute inflammation of the hoof dermis without pus is usually caused by trauma, i.e. an external force impact. These include for instance the following triggers:

• stones (lodged in the lateral collateral groove or in the shoe, stepping with force onto a stone), which is why this form is also called "stone bruise"
• incorrectly fitted/applied horseshoes (e.g. too short or too wide, pressing side clips, etc.)
• pressure from horseshoe nails
• banging of the hoof against the box wall or obstacle poles

Often the corresponding spots later show, when they grow out, on light-coloured hooves as yellowish or orange-reddish discoloured horn that is often also more compressed ("emergency horn"). On dark hooves such discolourations are not visible, but the spots are of course present there just the same.

Aseptic inflammation of the hoof dermis normally subsides on its own once the cause is removed. However, the hoof can be supported by relieving the inflamed area and providing a soft surface (e.g. in a softly bedded box or also with temporary hoof protection). In more severe cases, painkillers and anti-inflammatory medication are also useful.

Text and images: Nathalie Kurz

>> Sources

• https://campus.fei.org/local/globalglossary/view.php?mode=letter&hook=pododermatitis
• https://kernkompetenz-pferd.de/hufgeschwuer-beim-pferd/
• "Der Huf: Lehrbuch des Hufbeschlages", Lutz-Ferdinand Litzke und Burkhard Rau, 2012, 6. Auflage
• https://www.tiermedizinportal.de/tierkrankheiten/pferdekrankheiten/huflederhaut-entzundung-pododermatitis-beim-pferd
• http://www.go-barhuf.de/index.php?p=156000