Yes, in horses as in humans, overweight is a scourge, believe in veterinarians. Often the owners say that their horses are nicer by being a bit chubby, but trust me, this is not a gift they are given. You are told what your horse risks if he is overweight, how to detect it and how to lose weight.
How can I tell if my horse is overweight? ⚖
Use the body condition scores. In 1997 a method of body condition scoring was published by the INRA (the famous score) ranging from 0 (emaciated) to 5 (obese). This method involves visually and palpating the fat deposits at 5 places on the horse’s body (to which we can add the rump). In relation to weight, this method has the advantage of not being dependent on the size of the horse.
Let’s look at those 5 spots criterias:
|Neck||Back of the shoulder||Ribs||Withers||Tail|
|1/5||Neck bones apparent||Hallow||Extremely apparent, skin on bones||Sharp, top of the scapula visible||Cleared tail|
|2/5||Slightly fallen crest||Slightly concave, thin fat deposit||Can be seen under thin skin layer||Marked and dry||Cleared tail|
|3/5||Fallen crest||Becomes flat, delineated fat deposit||Can slightly be felt||Comes slightly out||Tail slightly cleared, a slight fat deposit covers the vertebrae|
|4/5||Edge of neckline grippable in full hand||Convex, thick and soft fat deposit||Cannot be felt under the fatdeposit||Cannot be seen||Tail slightly detached, thick and soft fat deposit|
|5/5||Fallen crest drowned under the neck mass||Clearly convex, mass trembling at palpation||Greasy layer rolling under the hand||Drowned under a rounded fat mass||Massive, fat deposit forming a firm cushion around the tail|
Reference:  
How does it work?
Take the zones one by one and assign them the grade that suits the condition of your horse best (you are entitled to half points). Then, just average with the weights percentage. They are indicated on the last line of the table. 
Example of a horse graded with: 2,3,3,2,3
Body score = (2 × 0.1) + (3 × 0.2) + (3 × 0.55) + (2 × 0.1) + (3 × 0.05) = 2.8 rounded to 3.
And what this score mean?
Well, a food body score condition is situated between 2.5 and 3.5. Of course, seasonal fluctuations are normal (it is normal scores increase slightly during winter) 
“Some say that the perfect score will vary depending on race and / or discipline  (dressage horses would be better around 3 – 3.5). Unfortunately these are purely aesthetic assessments that do not take into account health aspects. A dressage horse at 3.5 / 5 may be better suited to the aesthetic criteria of the discipline. However, from a health point of view it could cause osteo-articular problems related to the overweight. Whichever the discipline, a horse will be healthier with a score of 2-2.5 than with a score of 3.5. “(Small insert from Marine Slove, our house vet)
What about the horses weight?
You can calculate his weight using several methods. Either you are lucky and you have a special weighing scale. Otherwise you can also use a special measuring tape. It is like a normal measuring tape used to measure the thoracic perimeters of the horse but which estimates directly the horse’s weight. Otherwise use a normal measuring tap.
When using a normal measuring tap, measure the height at the withers and the chest perimeter (measured at the girth passage). Finally, apply the following formula which gives the approximative weight of the horse (+-25kg):
Weight (kg) = 3 x Height at withers + 4.3 x Chest perimeter – 785  
⚠ This formula is valid for ridden horses only
One thing is certain, the weight alone is not enough to determine if the horse is overweight or not. Body composition (% fat and lean mass) is more important than weight itself. 
Okay, my horse is too fat. And then, what are the risks?
Overweight in horses can lead to quite some issues. Veterinarians at the Grosbois Clinic state some of these: 
- increased stress on the cardiorespiratory system
- increased risks of laminitis
- increased risks of orthopedic diseases development on youngsters
- greater stress on feet, limbs and joints
- difficulty regulating body temperature
- fat deposits around vital organs (overloading the liver and kidneys)
- decreased fertility
- increased lethargisity and tiredness
Osteoarticular constraints are easy to understand. To give you an idea, at the reception of a jump the horse can beer up to 4 times its own weight on the forelegs which land first . So you can imagine that if your horse is overweight, his tendons, joints and bones will be put at very severe tests. And not only when jumping.
📚Read more: 4 tips to deal with your horse’s arthritis
How to make him lose weight?
Well, that’s a little more complicated
First, things first: try to find the origin of his overweight. Overweight in horses may be linked to pathologies (eg Cushing’s disease, Equine Metabolic Syndrome, etc.). So first advice: call your vet!
Then, what must be remembered is: NO DRASTIC CHANGES IN THE DIET. Changes in the diet shouldn’t happen overnight. By doing so, the intestinal flora of your horse won’t have time to adapt to its new diet. Which can cause diarrhea, liver failure resulting in colic, laminitis, or even
septicemia. Not cool … It is advisable to make the transition over an 8 to 10 days period, giving time to the intestinal flora’s enzymes and microbes to get used to their new diet.
Other tips: it is better to multiply meals (hay and concentrates), even for horses overweight so to get closer to their natural behavior. For example, you can divide the day in 6 different feeding times, 3 times concentrates and 3 times hay. For the concentrates, it is important to avoid varying the amount and composition of one meal on the other. Keeping it the same helps properly stabilizing the intestinal flora. For example, it is not recommended to feed 1 meal of barley, then 1 meal of oats and 1 meal of pellets.
📚Read more: The 3 things to avoid when feeding your horse
Hay and straw
What do we do about this? Well, horses that have belly is often due to straw eating. To avoid that, you could put them on shavings and feed them good quality hay instead.
Otherwise, for really fat horses, keep them to a hay ration only! And no, it’s not abuse! Your horse will be better off concentrates!
For fit horses that do not work every day (there are lots of dressage horses that train very technically but only 3 days a week), we can increase the workload. It’s like us, to lose holiday fat, we shall run!
Be careful though, increasing a fat horse’s workload can increase the risks of osteo-articular constraints. Make sure to properly feed him!
Little “energetic” parenthesis
Let’s take the exemple of a 550 kg horse, he works 1 hour / day, and needs 6 UFC/ day (Unité fourragère cheval = 2200 kCal net energy – that corresponds to the energy released by 1 kg of barley). This corresponds roughly to 5 kg of meadow hay (0.5-0.6 UFC / kg) + 3.5 – 4 kg of pellets (0.8-0.85 UFC / kg – to be verified on the label ). It is important to know this so to identify the exact diet of the horse. Remember to check the UFC numbers of your pellets because some of them can go up to 1 UFC / kg. This is very energetic and could explain the weight gain.
What if my horse is too skinny?
If the horse is too skinny, the first step is to call the vet to find out the origin of the slimming. The 3 main causes are usually:
- Teething problems
In all 3 cases, your the vet is required
What most of the time helps getting a horse back in shape is feeding him a more energetic ration by adding fat. Oil for example! The advantage of fat is that you avoid laminitis risks which can be caused high in starch rations. So you can give the equivalent of 100 to 120 ml of mixed oil 2 times / day in the horse’s ration.
You can increase the hay ration or feed it all day long. Also, you can add probiotic supplements. They will encourage the intestinal flora activity. Careful, remember to lower the ration once the appropriate weight has been reached, otherwise he will continue to gain weight!
That’s all I had to tell you about your horse’s weight. There is a lot more to know but I hope this was enough to convince you to pay more attention to your horse’s feed. Overweight can be a big issue with irreversible consequences. Maintaining an ideal weight must go well beyond our aesthetic considerations.
Till next article!
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 Doligez P. – Comment interpreter la note d’état corporel du cheval (NEC) – juin 2016 – Article equipaedia – Haras Nationaux Disponible en ligne sur http://www.haras-nationaux.fr/
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