How do I make his tail thick?

Here is an article that you might find interesting - it is written mostly for those who show and whose horses don't live outdoors with things to rub on (or low hanging branches, etc) 24/7 - some of it may not apply to you but some of it could be helpful - ..LONG!

Most horses have the tendency to grow a naturally long mane and tail on their own, even without human intervention. Horses kept in stalls for most of the day with constant grooming and attention do not have a notable advantage over pasture kept horses. The secret of growing long manes and tails in horses is a careful balance of diet and technique.
Healthy Horse, Healthy Manes and Tails

The first and most important thing that will help grow a long mane and tail is to make sure the horse is fed an adequate diet complete with all of the nutrients and fats that he needs to maintain basic metabolic processes. This includes a proper amount of roughage combined with a supplemental bagged feed (if the hay quality isn’t up to standard) combined with the proper balance of vitamins and minerals.

An owner should be careful not to add excess supplements, fats or oils to the diet if the regular diet already provides the proper amount of nutrients. Vitamins, minerals, fats, proteins and other ingredients are already properly balanced in most commercial horse feeds produced by reputable companies. In fact, over supplementation is not only a waste of money, but can be detrimental to the horse’s ability to utilize his feed.

In order for a horse to look healthy on the outside, he must be healthy on the inside. Once a good feeding regime is established and the horse is getting the nutrients he needs, the horse’s coat will produce a natural shine, and long healthy manes and tails will follow.


Growing a Long Mane

One of the secrets to growing a long mane is to wash it about two to three times a week. Manes should be washed with a mild soap, conditioned about once a week, and braided. Avoid the regular use of spray on conditioners if possible, and resist using colorizer or whitening shampoos unless specifically needed for a show weekend.

If the mane is long enough to be braided, it should be kept in braids of about one inch width. They should be loose enough that the horse won’t break the hairs at the crest of the neck when grazing. Once the hairs begin to pull free at the crest, it is time to wash and rebraid the mane. Keeping hair braided can help limit UV exposure which causes brittle hair and discoloration.

When washing the mane, the owner can stimulate hair growth by vigorously massaging the root bed with his fingertips. This also loosens up any dead skin and other irritants that inhibit the production of hair from the follicles. The skin at the roots of the mane should always appear clean and flake-free, and the hair should not come out easily when brushing.
Horse hair takes a long time to grow and these tips can help encourage the growth process:

• Avoid regular use of shampoos and conditioners with shine or color enhancers
• Always start brushing from the ends and work up to the roots
• Brush gently to avoid breaking the hair
• Keep hair braided to help avoid UV damage
• Massage the root beds as often as possible to encourage growth
• Protect horses from biting insects

Growing a Long Tail

Growing a long tail is not a difficult process, but it does take time. Horses use their tail as their main protection from biting insects, and it can take its toll. Frequent use of fly sprays can help keep the horse from swatting, but exposure of the tail to these chemicals can cause the tail hair to become dry and brittle.

The use of a tail sock during fly season is a great way to protect the tail. Horses living in pastures with shrubs or other types of brush would require frequent rebraiding of the tail sock. Tails should be washed and conditioned like manes, again stimulating the root beds, and left alone. The tail should never be brushed unless resolving a matted area or getting ready for a show.

The key to growing length in the tail and mane is to avoid pulling the hairs when brushing, which causes weak spots that eventually turn into breaks. A healthy diet, regular (but not too frequent) grooming and cleanliness are the trick to beautiful manes and tails.

I know a way to NOT grow healthy manes and tails...

Feed your round bales in a poly hay bale feeder. My horses ate out of one for one measly month and completely roached their manes! The friction from the plastic took all of their hair out. I swear it happened over night. One day they had manes, the next they were gone!

It has taken a ENTIRE YEAR to grow them back out 3/4 of the length they were at. So expect that it will take awhile to grow that tail out....it will take some patience!

Lol, mine's tail isn't really bothering me that much (I don't show in a discipline that's judged on appearance) but I do love thick tails.

Honestly next door's gelding and his lovely tail, it was amazing when they got him, but they haven't looked after him or it very well so his tail is all matted with poop in it. It's gross. My girl's was like that when I got her and I assume I broke and pulled out a lot of it getting the mats and poop out... plus Magic's only 22 months old.

I have used this product and liked it:

DOO GRO - Doo Gro Deep Down Conditioner

I typically will pack it into the tail and leave it until the next time I rinse my horse.

Some friends of mine use Mane & Tail Conditioner in the same way and have had great results.

MTG. I use it on my gelding once a week .
& it has grown back SO fast.
It does smell like bacon grease though.

I used MTG on one of my horses mane and it did help a lot to thicken and lengthen it. You do have to be careful with it though because some horses are sensitive to it and it can burn their skin. They suggest to use it in the evening just before dark. And yes, it will make your horse smell disgusting! My other mare with a thin, short tail, I used MTG for a brief period but I found that conditioning and braiding works well. I just made sure to run my fingers through it a little and re braid every few days to keep it from getting tangled and maybe a spritz of detangler every now and then.

One fall my mare scratched a significant portion of her tail out, so over the winter this is what I did:
1) I washed it with good shampoo, then let it set in conditioner for a while. Then I rinsed real good and let it dry.
2) Then I applied Shapley's MTG to it (the directions are pretty straightforward;)
3) Once her tail was good and dry (IMPORTANT), I braided it (braid it loosely near the dock, it doesn't need to be super tight, that will only break/stress the hairs). After that I folded her tail up on itself until it was a little "bun" like thing, then I slid a soccer sock on it and sewed some yarn through several times to hold it in real well. (One of my horses had a hard time keeping it on, so I used electrical tape wrapped around on top of the yarn, and this helped!)
Every 2 weeks or so, I'd take it out and redo it though, just to get the best results!

Just my 2 cents worth, but it did work really well for me! Her tail grew several inches and all those annoying short hairs on her dock grew out and made her tail MUCH thicker! Hope this helps and good luck!!:)

Oh and one more thing, I usually only do this when the flies are gone, but if you need to do this before then, attach some strands from a mop to the tail, so she can swat those flies too!:)

For my mare all I do is untangle it with my fingers, and I never brush it only if I HAVE to, and I occasionaly braid it. I have never bagged it. This is all I do and her tail drags on the ground. Like others said it could be genetics. For example a arabian usually has a longer tail thanan appy.
Hope this helped!