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Salt Intoxication in Commercial Broilers and Breeders –
a Clinical and Pathological Description
Perelman, B.,1* Farnoushi, Y.,2 Krispin, H.3 and Rish, D.4
Poultry Veterinarian-Clinical Consultant, Kibbutz Beit Kama, Israel.
Department of Avian and Fish Diseases, Kimron Veterinary Institute, Beit Dagan. Israel.
3
Yavne Hatchery, Kibbutz Yavne, Israel.
4
Poultry Veterinarian-Clinical Consultant. Beit Halevi, Israel.
1
2
* Corresponding Author: Dr. Beny Perelman, Kibbutz Beit Kama, POB 38. D.N., Negev, Israel, 85325. Tel: 0549755905. Email: benyperelman@gmail.com
AB S T RAC T
Several broiler commercial farms were affected with different overdoses of sodium chloride in their feed.
Within a period of about one month about six commercial broiler farms and one breeding farm, all from
the southern part of Israel were affected. The clinical picture ranged from increased water consumption and
wet litter without any mortality to houses with 20% mortality and severe clinical and pathological findings
typical of sodium intoxication. The most affected broiler flocks suffered from increased mortality of chicks
from 5 days of age with many chicks appearing on their backs paddling and showing difficulty in standing,
severe respiratory distress, apathy and some neurological signs suggesting brain involvement such as lack of
coordination and opistotonous. Pathological findings included severe subcutaneous edema, accumulation of
clear fluid in the pericardium, ascites and enlarged kidneys. Mortality reached in the most affected flocks
was more than 20% within 7 days. The breeding flocks affected by salt overdose did not show any mortality
or clinical signs, but suffered from increased water consumption and wet litter and a drop in egg production
of up to 8%. Post mortem examination in these flocks revealed enlarged swollen kidneys. Salt or sodium
intoxication in poultry is an exceptional situation in the modern poultry industry. In this report we describe
the clinical and pathological findings of feed related salt/sodium intoxication at different concentrations and
at different ages in broilers and breeders due to technical problems in production at the feed mill.
Keywords: Broilers; Salt intoxication; Poultry Feed; Mortality; Chicks.
INTRODUCTION
Salt or sodium intoxication may occur in any animal species
and studies have been carried out to determine the salt toxic
levels in chickens, turkeys, ducks and pigeons (1). During the
last 50 years the poultry industry has developed from a relatively small and primitive rural farming setup to a state of the
art mass production industry with computerized controlled
environmental conditions. The advance in poultry farming
and production involved vast technological developments of
the feed mills, feed production and quality control systems.
Search of the literature reveals that after the 1990’s salt
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intoxication reports are very rare and deal with crude mistakes in small rural farms such as the case reported in New
Zealand by Howell in 1992 (2). Salt intoxication presents
the same clinical and pathological findings of other sodium
related compounds such as sodium iodide, sodium bicarbonate, and sodium sulfate as reported by Scrivner in 1946 (3).
Because these kinds of intoxications are seldom observed in
the modern poultry industry, it is important to describe and
publish this type of incident.
Israel has a highly developed poultry industry and most
of the broiler production is carried out in state of the art
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computerized environmental controlled houses. Feed mills in
Israel are modern and fully computerized and production of
poultry feed if followed by strict quality controlled measures
and laboratory analyses. Despite all this technological amenities, a relatively extensive salt/sodium intoxication incident
involving several broiler farms with more than one million
chicks and two breeding flocks involving about 50,000 birds
was observed in 2015 in the southern part of Israel. The clinical picture and economic damage encountered was directly
related to the levels of sodium found in the diets as well as
the age of the chickens involved.
CASE REPORT
The first suspicion of a possible salt excess appeared in 3
different broiler farms involving chicks from 10 days old to 30
days of age. The main findings were wet litter and an increase
in the water intake above the normal. Feed samples sent to
the feed mill laboratory showed mildly increased salt levels
above the recommended levels of salt (0.2-0.25%).
The episode was first observed when about three days
after changing the feed from pre-starter to starter at 10 days
of age, a sudden and sharp increase in mortality begun in one
house in one of the broiler farms, showing large numbers
of apparently healthy chicks lying on their backs (Figure
1) and pedaling with their feet. When the position of the
birds was manually corrected the chicks showed difficulty in
walking, showing spread legs and falling again on their backs.
Other chicks showed severe depression and apathy with some
clinical signs of brain involvement such as incoordination
Figure 1: Six days old broiler chicks laying on their backs with spread
legs due to ascites and anasarca
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Perelman, B.
March 2016.indb 54
and head opistotonous. Many birds within the flock showed
severe respiratory distress (Figure 2) similar to that observed
in post vaccinal respiratory reactions or infectious bronchitis.
The bird population in this building was 34,000 birds and
the mortality increased from about 40 birds per day to 200
per day reaching a peak of 400 dead chicks per day. Due to a
suspicion regarding the feed it was decided to cease feeding
and change to a new batch of feed. The clinical signs and
mortality however continued for the next 48 hours and then
declined gradually reaching normal levels of 1 in 1,000 birds
within one week after withdrawal of the suspect feed. The
total mortality related to the suspected salt problem in this
house reached about 5%.
Feed was sent to the feed mill laboratory and to an independent laboratory (Bar Magen, Israel) for analysis. The
results obtained by the feed mill laboratory reported salt
levels of 0.4% (based on the chlorine concentration) while the
results of the same sample sent to the independent laboratory
showed levels of 0.9% of salt based on the sodium content.
The next outbreak of suspected salt poisoning occurred
in a kibbutz broiler farm with about 200,000 chicks reared in
four different areas each one rearing between 50,000 to 75,000
chicks. In three out the four rearing areas a sudden increase in
mortality was observed in chicks between 6 to 9 days of age.
Clinical inspection revealed many chicks on their backs on
the floor similar to the signs observed in the previous case. In
some houses mortality started to increase from 0.2% per day
to 0.5% per day after day five, some houses showed affected
chicks with severe clinical signs while other houses at the
same rearing farm did not show almost any clinical signs or
Figure 2: Six days old chick gasping showing respiratory distress
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increase in mortality. All the houses received different batches
of a pre-starter feed from the same feed mill.
Within 24 hours and before suspected feed could be removed from the affected houses a sharp increase in mortality
and severity of clinical signs was observed in the youngest
birds reaching about 5% mortality per day with thousands of
chicks falling on their backs with severe difficulty in breathing. Total mortality in the most affected houses reached 20%
and returned to normal within 10 days after withdrawal of
the suspected feed.
Feed samples were sent to the feed mill laboratory and
levels of 0.8% salt were found according to the same analytical method (chlorine concentration) and equipment. When
the same samples were sent to an independent laboratory,
the sodium content in the feed samples reached 1.2% (4).
Histopathological examination of muscles, heart, kidneys,
and brain did not reveal any abnormal histopathological
changes in these organs.
Salt/sodium intoxication in breeding flocks
PATHOLOGICAL FINDINGS
In all the affected broiler farms the pathological signs were
very similar: dead chicks and chicks laying on their backs
showing swollen edematous shanks (Figure 3) and extensive subcutaneous edema (anasarca) (Figure 4). Muscles of
affected chicks showed a pale color and their consistency
was soft and watery (Figure 5). Affected chicks showed
enlarged hearts with a large amount of clear watery fluid in
the pericardial sac (Figure 6). Some chicks showed ascites
in the abdominal cavity and enlarged pale kidneys without
accumulation of urates.
Two breeding farms were affected: One flock consisted of
24 weeks of age birds which were not laying eggs as yet.
The other flock had 45 weeks of age breeders in full egg
production.
The 24 weeks old flock showed a sharp increase in water
intake from 1:2.2 feed to water ratio to 1:3 feed to water ratio.
No mortality or clinical signs were observed in the birds; litter became wet within 48 hours after the last feed batch was
fed to the birds. Samples of feed sent to the feed mill laboratory reported levels of 0.3% salt (based on chlorine levels)
while the same samples tested by an independent laboratory
showed salt levels of 0.6% based on the sodium content (4).
At about the same time the 45 weeks of age breeding flock
in full production showed a drop in egg production of about
8% in 4 days (Figure 7). The intake of water increased and
there was a slight increase in mortality.
Post mortem examination revealed only internal egg laying and enlarged kidneys. Trachea and cloacal swabs were
sent to a diagnostic laboratory due a suspected Infectious
Bronchitis involvement in the drop of egg production and the
enlarged kidneys found in the dead birds. Feed samples were
sent for analysis and determination of the levels of protein,
Figure 3: Six days old broiler chicks with swollen edematous shanks
Figure 4: Subcutaneous edema in a six days old broiler chick
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Ca, P, and NaCl. The same samples were sent to the feed
mill laboratory and to an independent analytical laboratory
(Bar-Magen, Israel)
RESULTS
All the trachea and cloacal swabs were negative by PCR and
viral isolation to IB, NDV or H9N2 viruses. Feed samples
analysis at the feed mill laboratory, revealed different levels
of protein, from 14% to 17.5% and levels of salt content
ranging from 0.3% to 0.5% (based on the chlorine content)
while recommended levels should have been 0.20% to 0.25%.
The same feed samples tested by an independent laboratory
revealed levels of salt ranging from 0.4% to 0.7% based on
the sodium content analysis (4).
Due to the large quantities of feed consumed by the
breeding birds the suspected feed was consumed in three
days and replaced by a new batch. Egg production started
to increase after the feed change and reached original levels
within 8 days (Figure 7).
Due to the cases observed in the field and the very different results obtained by the feed mill laboratory and other
independent laboratories, an investigation was carried out
by the feed mill technical staff in order to find out what
was causing the problem of salt/sodium excess. According to
the feed mill investigation a mechanical problem in the salt
dispensing system caused the excess of salt in some batches
Figure 5: Pale watery muscles in a six days old broiler chick
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Perelman, B.
March 2016.indb 56
of feed (each batch consisting of about 3 tons). The second
problem was that the laboratory at the feed mill calculated
the concentration of salt in the feed based on the chlorine
content, a test with much lower sensitivity to detect salt levels
than the methods used based on sodium content in the feed
(4).
DISCUSSION
Salt (NaCl) or sodium intoxication is a very rare event in the
modern poultry industry. The high standards of feed production as well as the quality control and analytical methods
enable the introduction of feed ingredients including salt
and microelements at accurate required levels reducing the
frequency of feed intoxications due to excessive levels of
ingredients such as microelement, salt or additives such as
coccidiostats or antibiotics provided in the feed.
Levels of NaCl in the feed can be determined by two
different analytical methods, the first one is based on the
determination of the chloride (Cl) levels, while the second
method is based on the determination of the sodium (Na)
levels (4). Because the ratio of chloride /sodium in salt (NaCl)
is 1:1, testing the levels of chloride (Cl) should provide a good
extrapolation for the determination of the levels of NaCl in
the diet. However, the main problem with this method is
that other sources of sodium such as sodium iodide, sodium
carbonate or bicarbonate or any other sodium based salt,
will not be detected. As demonstrated by Scrivner (3) all
sodium based salts can cause sodium intoxication showing
very similar clinical and pathological findings.
Figure 6: Enlarged heart with pericard filled with clear transudate in
a 6 days old broiler chick
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In this case the levels of chloride found in the samples
did not correlate with the levels of sodium as should be with
a NaCl excess only, suggesting the presence of another source
of sodium in the feed other than NaCl. While discussing
this point with the nutritionists in the feed mill it was found
that the feed mill was adding sodium bicarbonate in all diets
at levels of 1-2 kg/ton feed, increasing the level of sodium
toxicity caused by the excess of NaCl added to the feed due
to the technical problem with the salt dispenser.
Because the analytical technique used at the feed mill to
calculate the levels of salt (NaCl) was based on the chlorine
content only and the sodium was not tested, the feed mill was
not aware of the excess of sodium in the diets. The calculated
levels of salt in the diets by the feed mill laboratory ranged
between 0.4% to 0.9% instead of the recommended levels
of 0.20-0.25% salt, thus indicating that salt was added to
the feed in overdose. The constant addition of the sodium
bicarbonate in the feeds added to the amounts of sodium
thus increasing the sodium overdose in the feed.
Many different sodium salts can be involved in sodium intoxication (1, 3). Salt is a critical and an important component
of feed for broilers and breeders, (5). The modern commercial
production in broilers and breeders require very accurate levels
of nutrients and additives, microelements and vitamins as
well as antibiotics or anti-coccidial drugs. Lack or excess of
some of these ingredients may have very serious effects on the
health and production parameters of the flock (5).
The severity of the clinical signs and mortality in the
broiler farms was closely related to the salt/sodium levels
found in the feed as well as the age of the flocks, with younger
flocks having a much more acute and severe clinical picture
and a higher mortality (up to 20%). As mentioned in this case
report birds receiving low overdoses (0.4%) suffered only of
increased water intake and wet litter while the broiler flocks
receiving the highest concentrations of salt in the feed (0.91.2%) suffered from severe clinical and pathological disorders
as well as high mortality.
All the clinical and pathological signs observed and the
feed analysis results are indicative of an acute salt /sodium
intoxication, the severe respiratory signs observed in affected
flocks was probably related to lung edema which is a recognized sign of salt intoxication (3).
In a case like this it is important to make a complete
differential diagnosis as the clinical signs of incoordination;
chicks laying on their back unable to stand, opistotonous
and severe respiratory distress could be related to viral infectious diseases such as Infectious Bronchitis or Newcastle.
Subcutaneous edema as well as accumulation of fluid in the
pericardial sac and ascites could be also related in very young
chicks to problems of incubation connected to an excess of
humidity during the incubation period producing edematous
chicks. In this case different hatcheries were involved and the
hatchability rates of the involved flocks were normal.
The rapid reduction in egg production and the enlarged
kidneys could be suggestive of a viral infection such as
Infectious bronchitis or other viral etiology. The laboratory
results as well as the quick recovery in the affected breeding
flock after feed change indicates that the drop in egg production and the wet litter was related to the excess of salt in the
feed and not to a viral infection.
REFERENCES
Figure 7: Daily egg production (%) in a 45 weeks breeding flock
affected by excess of salt in the feed. A clear recovery of egg production
can be seen after feed change.
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1. Peckam, M.C.: Poisons and toxins. In Diseases of Poultry, Biester
and Schwarte, 5th Edition. pp. 1212-1252, Iowa State University
Press. 1967.
2. Howell, J.: New Zealand Veterinary Journal.40: 36,1992,
3. Scrivner, L.H.: Experimental edema and ascites in poults. JAVMA.108: 85, 1946.
4. Horowitz, W. and Latimer, G.: Official Methods of Analysis of
AOAC, Book by AOAC International, 18th edition, 2010.
5. Harms, R.H.: Effect of removing salt, sodium, or chloride from
the diet of commercial layers. Poultry Science. 70: 333-336, 1991.
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