Dictionary: kaltblut
AE should have draft horse, and both cart horse/carthorse, though draft horse is much more common. I was not familiar with heavy horse being used in AE, and it's not in the dictionaries, but it is used on sites catering to horse people.
https://www.merriam-webster.com/dictionary/dr...
noun Popularity: Bottom 20% of words
Definition of draft horse: a horse adapted for or used in drawing heavy loads; specifically : such a horse over 1600 pounds in weight and over 16 hands high — compare carriage horse, cart horse, chunk, saddle horse
http://www.drafthorsejournal.com/
Draft Horse Journal
The World's Foremost
Heavy Horse & Mule Publication
https://www.suffolkpunch.com/
But while these great titans clashed in mortal combat, the quiet farmers of eastern England went about developing their own breed of heavy horse, the Suffolk Punch. This one breed is today the least known to Americans, and yet perhaps has more qualities appealing to the American breeder and draft horse employer than any of the better-known breeds of draft horses.
https://www.merriam-webster.com/dictionary/ca...
noun Popularity: Bottom 10% of words
Definition of cart horse: a large strong horse bred or used for drawing heavy loads
https://ahdictionary.com/word/search.html?q=c...
carthorse:
n. A strong horse used for pulling carts or other heavy loads.
If you search "carthorse" in MW, it takes you to the open "cart horse" above.
I don't have dictionary evidence for heavy horse.
https://www.merriam-webster.com/dictionary/he...
"heavy horse"
The word you've entered isn't in the dictionary.
https://ahdictionary.com/word/search.html?q=h...
No word definition found
BE should have heavy horse, draught horse and carthorse.
https://www.heavyhorses.org.uk/
The characteristics and standards of the main heavy horse breeds are as follows.
https://www.telegraph.co.uk/sponsored/why-not...
Riding heavy horses: an adventure to remember
An animal that played an important role in British history, the heavy horse stands at over two metres high; here's where you can ride them in the UK
http://www.equine-world.co.uk/about_horses/sh...
The Shire horse is the largest of England's native horses and was used mainly as a draught horse.
https://www.repository.cam.ac.uk/handle/1810/...
But the thesis argues that, during the course of the nineteenth century, the driving classes, who favoured the breeding of draught horses and whose views were untainted through romantic associations with the ‘noble’ creature,
https://dictionary.cambridge.org/dictionary/e...
carthorse n.
a large, strong horse used for pulling carts
http://www.oxfordreference.com/view/10.1093/o...
Boxer, the noble carthorse, stands for the strength, simplicity, and good nature of the common man.
The German side in LEO says das Kaltblut no plural.
This contradicts duden.de, which lists Kaltblute.
https://www.duden.de/rechtschreibung/Kaltblut
Nominativ
Singular das Kaltblut
Plural die Kaltblute
Searching online, however, Kaltblüter seems to be the plural commonly used.
https://www.dw.com/de/eine-frostige-angelegen...
Im Gegensatz zu den rassigen Vollblütern, sind Kaltblüter unter den Pferden auch diejenigen, die sich durch ein ruhiges Temperament auszeichnen.
https://www.welt.de/regionales/sachsen/articl...
Die kräftigen Kaltblüter müssen bei dem Wettbewerb einen acht Meter langen Baumstamm durch einen Parcours manövrieren - und dabei so wenig wie möglich Fehler machen.
http://www.kaltblut-pferd.com/
Die größte Pferderasse, die heutzutage auf der Welt verbreitet ist, gehört selbstverständlich auch in die Kategorie der Kaltblüter. Hierbei handelt es sich um das Shire Horse.
https://www.swr.de/swraktuell/bw/heilbronn/hi...
Verwendet für diese Arbeit werden vorwiegend Kaltblüter, da diese Pferde schwer, kräftig und gutmütig sind. Die Ardenner-Rasse ist eine der ältesten Kaltblüter-Pferderassen. So ein Pferd kann bis zu einer Tonne und mehr wiegen.