Excessive salivation, characterized by drooling or frothy saliva around the
lips, may be caused by a variety of things including chemical irritants fungal
toxins, virus and bacterial diseases affecting the mouth, teeth problems,
choking caused by esophageal obstruction, and various toxic or injurious plants.
Grazing animals that eat sharp grass awns, spiny plants such as the prickly pear
cactus or those with burs such as burdock and cocklebur may injure the oral
mucosa. Some common grasses such as foxtail barley bristle grass and sandbur
have seeds with sharp awns that can become embedded in the tongue and
gums of animals eating them. Initially excessive salivation may be noticed, but
in time the grass awns or spines that are imbedded in the mucosae create large
ulcers. The awns are not easily visible in the ulcers because they become
embedded in the granulation tissue filling the ulcer. It is not uncommon for
some sharp grass awns to penetrate the skin of animals, migrate through the
tissues, and act as a foreign body causing abscesses and draining wounds far
from the site of penetration .
Profuse salivation has been observed in horses,
llamas, and other livestock eating
clover or alfalfa pasture or hay that is infected with the fungus Rhizoctonia
leguminicola. The mycotoxin responsible for the "slobbering" that
animals exhibit has been identified as slaframine, an indolizidine alkaloid
produced most commonly by the fungus R. leguminicola growing on red
Slaframine is chemically similar to the alkaloid swainsonine produced by plants
of the genera Astragalus and Oxytropis that are responsible for
causing locoism. Under wet or humid conditions the fungus grows on the leaves
producing black or brown spotting. After they eat the fungus-infected clover for
several days, horses begin to salivate excessively and lose weight; pregnant
mares may abort if they continue to consume the infected clover. Recovery occurs
rapidly once horses are removed from the infected hay. Problem pastures can be
used for animals if they are mowed, the affected hay is removed, and the
regrowth has no brown spotting on the leaves.
Professor of Agronomy and Forage Crops Specialist - Purdue University
1150 Lilly Hall of Life Sciences
West Lafayette, IN 47907-1150
The Slobbers - Black
The slobbering is associated with black
patch disease caused by Rhizoctonia leguminicola. The specific
causal agent is slaframine which is an indolizidine alkaloid and a metabolite of
Rhizoctonia leguminicola. Conditions were right for its
development this year, rainy conditions and high humidity.
Interestingly, the compound does decrease
in red clover hay while in storage, but only after a period of time. One study sites a decrease in 10
months of storage from 50-100 ppm to 7 ppm.
Reading about the associated biological
effects in Peter Cheeke's "Natural Toxicants in Feeds, Forages, and
Poisonous Plants" book makes one raise their eyebrows as to why we even use
potentially infectious clovers at all. In cattle, concerns include
excessive salivation, eye discharge, bloat, frequent urination, watery diarrhea,
reduced milk production, weight loss and abortion. Other things noted
include increased pancreatic flow, bile flow, and gastric acidity, and decreased
heart rate, cardiac output, respiration rate, body temperature, and metabolic
rate. With use of guinea pigs as an assay animal, the LD50 was less than 1
mg of slaframine/kg (1 kg=approximately 2.2 lbs.) of body weight.
Applying some mathematics and assuming a
guinea pig and horse have a similar lethal dosage response, a 100 ppm slaframine
forage fed to a horse consuming 25 lbs. of dry matter is equivalent to 11.35 mg
of slaframine. Assuming the horse weighs 1000 lbs., this is a dose of .025
mg/kg of body weight, much less than the lethal dose rate found in the guinea
So do you get rid of the clover? If
you truly don't enjoy your llamas or horses because of the slobbers, maybe so.
Keep in mind, that you may not see slobbers to the same extent each year - it
will depend on the weather.
You need to balance the positives and
negatives for the use of red and white clover in your pasture. There are
many positives (forage quality improved, more summer pasture with use of
red clover, no N fertilizer needed for the grass component of the pasture)
when legumes are a part of the pasture. Is this worth more than the
negative issue of slobbers? This is a judgmental call that I think
you need to consider.
Maybe other type
grasses should be the
choice when seeding your next hay and pasture fields?