Question
I own an 18-month-old Quarter Horse yearling with a body condition score of 2 or 3. She has lost an incredible amount of weight for her size (13 hands). Five months ago, she required surgery for a severed tendon in her pastern. Along with stall rest, she was given antibiotics. Once stall rest was over, she was allowed turnout. She seemed to be doing well enough within the herd, though she was at the bottom of the pecking order. She ate from hay piles once the other horses had wandered away from them. The pasture is sparse. Six weeks ago, I noticed she was quite thin. I fed her separately for a week and then consulted with my vet, who made the diagnosis of liver failure with elevated white blood cell count. The vet prescribed more antibiotics and suggested a low-starch grain. She is also fed unlimited coastal Bermudagrass hay and a flake of alfalfa each day. She prefers the grass hay. I added some milk thistle, alternating it with a commercial herbal liver-support supplement. She’s not a fan of actually eating the supplements some days, however. She still isn’t gaining weight, although her attitude seems better. She also had diarrhea but that has improved from pure liquid to cow-plop consistency with a probiotic. I read about vitamin E, but I don’t want to overload her system or do more harm than good. Surely there is something more than just low-starch grain I can be doing?
Answer
Has your vet identified the cause of the liver disease? The first thing that comes to mind is the possibility of toxicity from a pasture plant eaten during or after her recovery from surgery. A list of plants that damage liver cells (called hepatotoxic plants) is included at the end of this answer. If you’re unsure of the plants that grow in your pasture, I would encourage you to identify as many of the plants as possible, even if you have to recruit assistance from an expert such as a local agricultural extension agent. Given that you describe the mare as submissive within the herd, she might have been pushed away from good-quality hay and forced to eat whatever pasture plants or weeds were accessible. Some of those might have been noxious.
Pasture grass is one of the best ways to supply forage in combination with free-choice grass hay when she is stalled. It is important for her to have 24/7 access to forage to help reduce large fluctuations of nutrients passing through the liver. Because you describe your pasture as sparse, you should continue to separate her so she can eat without worrying about being chased from the hay.
In horses with liver disease, protein intake becomes a balancing act. The diet should not supply excessive protein, which would tax the liver, but should provide enough for optimal health. In this instance, the balancing act is especially important because the filly’s diet must meet both maintenance and growth demands. Coastal Bermudagrass hay has varying levels of protein, so a hay analysis would reveal exactly how much protein it is contributing to the diet. Equi-Analytical is an excellent resource for hay analysis if you do not have a local resource.
You mentioned she prefers Bermudagrass hay to alfalfa hay. Another option is to mix soaked alfalfa pellets into her concentrate meals. Adding some soaked beet pulp to the mix would provide high-calorie roughage without adding too much protein. A mash of alfalfa pellets and beet pulp mixed with her feed will extend the amount of time it takes to consume each meal. The total daily amount could be around 1 lb/200 lb (0.5 kg/100 kg) body weight of the two combined. This may also help with the diarrhea. Providing four to six small meals a day is ideal. I understand that can be challenging from a management perspective, so even three meals per day is better than two.
The current low-starch feed is fine, but it is important not to add any more fat to the diet for now to avoid fat buildup in the liver. Low-starch feeds are often recommended because insulin resistance is sometimes a consequence of liver disease. However, it is unlikely that this would happen in a horse her age. Adding a small amount of starch will keep the liver from having to work hard as it makes glucose to fuel the brain, a process known as gluconeogenesis. Less than 1 lb (0.5 kg) of oats per day split between meals would be a way to supply a little more starch to the diet.
In regards to supplementation, you may find she will be more interested in eating them when they are mixed with the mash meal. If she is still not interested, wheat bran can sometimes be a good option to help cover flavor. Vitamin E is currently recommended for humans with liver disease, and it is also advised for horses to ensure the diet has two times the recommended levels of fat-soluble vitamins. Given her low feed intake, vitamin E is a potential shortcoming in the diet. Supplementation with 1,000 IU of Nano-E will deliver a highly absorbable form of natural-source vitamin E to meet her needs and support her condition. Avoid supplements high in iron and do not add any salt to the diet. The sodium provided in the feed is enough in this situation.
A list of the hepatotoxic plants* follows:
- Tansy ragwort, stinking willie (Senecio jacobaea)
- Lamb’s tongue groundsel (Senecio integerrimus)
- Woody or threadleaf groundsel (Senecio douglasii)
- Ridell’s ragwort (Senecio riddellii)
- Prairie ragwort (Senecio plattensis)
- Broom groundsel (Senecio spartioides)
- Butterweed (Senecio glabellus)
- Common groundsel (Senecio vulgaris)
- Fiddleneck, tarweed (Amsinckia spp.)
- Rattlepod, rattlebox (Crotalaria spp.)
- Hound’s tongue (Cynoglossum officinale)
- Creeping indigo (Indigofera spicata)
- Alsike clover (Trifolium hybridum)
- Kleingrass (Panicum coloratum)
Australian horse owners should refer to a trusted source of information such as Plants Poisonous to Horses: An Australian Field Guide.
*Knight, A.P., and R.G. Walter. 2001. A guide to plant poisoning of animals in North America. Teton News Media, Jackson, Wyoming.
