Q. My new 2-year-old filly is obsessively licking and biting her salt block. She lives on a dry lot and gets high-quality orchard grass hay, a daily ration of commercial horse feed appropriate for her growth stage and size, and an omega-3 supplement. She also receives ample fresh water. Her current workload is very light and mostly includes basic handling rather than exercise. I haven’t had blood work done on her. Should I be concerned about her licking and chewing the salt block? Does it suggest there’s a problem with her diet or health, and can she hurt herself by taking in too much salt?
—Bill, via e-mail
A. This is a very common question. The good news is that sodium chloride, commonly known as salt, is water-soluble. As long as your filly has ample fresh water as you indicate, and she’s actually drinking enough, excess sodium will simply be excreted in the urine.
The National Research Council (2007) reports the maximum tolerable intake of sodium chloride to be at about 6% of total dietary intake, presuming adequate water intake. Assuming your filly matures at about 1,100 pounds and consumes 2-2.5% of her body weight in forage and feed per day, this equals just more than 1 ½ pounds of salt per day. Few horses consume anywhere near this much.
However, be aware that signs of salt toxicosis include colic, diarrhea, frequent urination, and general weakness. You should consult your veterinarian immediately if your horse exhibits any of these clinical signs.
Horses have a defined appetite for salt and will seek to consume sufficient amounts to meet their needs. Most commercial feeds do not contain sufficient salt to meet a horse’s daily needs, and salt content of forages is usually low as well. Thus, it is recommended to provide a salt block and water at all times.
There are many reasons why she may be obsessively licking and biting at her salt block, including boredom. When kept on dry lots, horses will often search for things to forage (or chew) on, from fence posts to salt blocks. If it is possible, you can try to spread out her hay ration into three to four feedings per day so that her “chew time” is spread out a little bit.