Your Horse’s Healthy Frog

A healthy frog usually appears broad and flat, with narrow clefts (also called sulci) along the side and a shallow central cleft. The central cleft should look more like a thumbprint, or a wide dip, rather than a deep narrow crack. The tip of your hoof pick should not disappear into the frog clefts when you are cleaning the feet out.

These to two photos are taken at different times of year, one during the summer and one during the winter, from the same hind foot of a 5 year old Arab gelding. You can see the different appearance of the frog texture during different times of year.

Healthy frogs will vary in consistency depending upon the ground surface. In wet terrain, they will be more “plump” and in dry terrain, they will be leather-like. Unhealthy frogs may be either too big or too small.  There are no quantitative studies to tell us exactly what size the frog should be in relation to the rest of the foot. However, qualitative assessment guides the farrier each time a decision is made to trim back an overgrown frog or rebalance a foot to encourage a change in frog size. Keep in mind that unhealthy usually feet have multiple signs of dysfunction. Frog atrophy (shrunken) or hypertrophy (over growth) generally happens in conjunction with other dysfunction.

A frog that is too big will tend to have a swollen appearance, almost as if it is about to burst open. The back part of the frog becomes bulbous and is usually soft, sometimes with cracks around the edges. Generally, with such a frog you find under run heels and flared wall in the quarters. It is common to see overgrown frogs on flat feet with weak walls. This may be because the frog has overgrown as a way to support the back of the foot when the walls and heels are unable to do so.

Small, sometimes thin shrunken frogs are commonly seen. The frog tissue is either rock hard or so squishy that you can stick the tip of the hoof pick deep down into the central cleft. Frogs that are too small are usually found on contracted feet or those with high heels in which the frog has no ground contact. Small frogs are more commonly seen on front than hind feet.

Frog that appear shrunken, misshapen or look like they are rotting may have thrush. Thrush is a bacterial infection in the frog but the bacteria are commonly present in the soil and normally do not invade the hoof. So although thrush is an infection, the actual cause is a weakened local immune response in the frog tissue that allows a normally harmless bacteria to become pathogenic. Treating thrush involves topical antimicrobial treatment but the problem will recur if the underlying cause is not addressed. Although a wet environment may be one co-factor in the development of thrush, horses living in desert conditions can still develop thrush. Likewise with dirty stalls: standing in manure and urine is not ideal for hoof health but that alone is not enough to cause disease.

Check to see if your horse have any signs of the following signs of thrush: decaying appearance of the frog, deep sulci with black ooze coming from the cracks, sensitivity to a hoof pick. If so, your farrier might find that rebalancing the hoof, in addition to applying a topical antimicrobial will improve the frog health. In addition your horse may need more exercise. A horse that moves more will usually develop a healthier frog.


This photo shows a frog with several signs of thrush, worse along one side but it is all around the edges of the frog including some diseased tissue in the central sulcus.



In general, badly proportioned frogs with poor quality horn tend to appear when the back of the foot is not functioning properly. When the horse’s feet receive balanced hoof care, the walls and heels become stronger and more functional, allowing the frog to assume a normal size, shape and consistency.

A central goal of your hoof health assessment is to develop your eye for ideal proportions and horn quality that suggests a foot is able to efficiently deal with the demands placed upon it.


Copyright © 2012 ~ Dr. Lisa Lancaster DVM, WDAA Blog Author


5 Responses to “Your Horse’s Healthy Frog

  • Hi,
    How does one correct a large frog that supports the foot with no heel growth?

    • Lisa Lancaster, DVM
      6 years ago

      Hi Shelby,
      This is a great question but unfortunately I do not have a great answer. It is quite common to see feet with large frogs and insufficient heel growth. It may be a result of bad posture that puts too much pressure on the heels and then growth is slowed. Sometimes on physical exam I detect musculoskeletal pain, in the foot or elsewhere in the body. If that pain can be treated, the horse may stand with better posture, which can result in improved heel growth. But in some cases, even if pain is found and treated, heel growth may not improve. In these horses the best I can do is keep the foot as well balanced as possible by preventing toe length from getting too long.

  • patricia
    6 years ago

    Why does he have a,white,foot,in,the dry photo and a black foot,in,the wet photo

    • DMD-Admin
      6 years ago

      I think what you are seeing is the dark sleeve of the person holding the leg. Look on the left side and you will see the hoof is white.

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