As a consequence of high
concentrate feeding often in preparation for sale, rams are prone
to several conditions including urethral obstructions (calculi),
copper poisoning and acidosis (grain overload, barley poisoning).
These conditions can be prevented by careful management, with
veterinary advice as necessary, supplied in the flock health plan.
It is important that these conditions are identified quickly to
allow prompt treatment and prevent problems in other sheep within
the same group. Thereafter, stresses associated with transport,
management changes and adverse weather during the mating period may
precipitate problems after sale. All rams should be fully
vaccinated against clostridial diseases.
Urolithiasis (Partial or complete urethral
Partial or complete urethral
obstruction (blockage of the narrow tube within the penis
connecting the bladder to the exterior) is not uncommon in
intensively-reared rams. Early recognition of clinical signs by the
farmer and prompt veterinary treatment are essential to ensure a
satisfactory outcome because irreversible kidney damage quickly
results from excessive urinary back pressure. Early diagnosis is
also important to allow rapid implementation of control measures to
reduce the occurrence of future cases.
Fig 1: Normal
urination with a continuous free flow of urine - dripping of urine
is highly suspicious of urethral obstruction and immediate
veterinary examination is essential.
The most common cause of
urolithiasis is a crystal composed of magnesium ammonium phosphate
hexahydrate (struvite) resulting from feeding concentrate rations
high in phosphate (> 0.6 per cent; typically grain-based
rations) and magnesium (> 0.2 per cent; typically found in ewe
rations). Calculi may lodge within the urethra at a level just
above the scrotum/sigmoid flexure or within the vermiform appendix
("worm") at the tip of the penis.
The early clinical signs of
urinary tract obstruction include discomfort (abdominal pain),
teeth grinding, with separation from other sheep in the
Fig 2: This ram
with partial urethral blockage is dull and inappetant, and was
separated from other sheep in the group.
Fig 3: Affected
sheep, especially growing lambs may show frequent tail swishing and
present a wide stance with the hind legs held well back, and
Fig 4: Urethral
obstruction of several days' duration. Note the ram's painful
expression and swollen prepuce.
Affected sheep do not feed
and there is frequent straining and teeth grinding (adults). Only a
few drops of blood-tinged urine are voided rather than a clear
continuous flow of urine. Crystals are frequently present on the
preputial hairs of normal male sheep and are not necessarily
indicative of urolithiasis. Rupture of the urethra/penis may occur
in sheep neglected after a few days with resultant extensive
swelling extending from the scrotum towards the prepuce.
Fig 5: Massive
bladder distension confirmed at necropsy - this ram had developed
irreversible kidney damage because clinical signs were not noted
for several days.
Fig 6: Rupture
of the penis which has resulted in urine accumulation under the
skin extending between the scrotum and the
Accurate diagnosis requires
prompt veterinary examination. The penis is extruded and the
calculus can be felt within the vermiform appendix in most cases
occurring in mature rams. Diagnosis is confirmed following excision
of the vermiform appendix with production of a free flow of urine
once the ram stands.
Fig 7: Extrusion
of the penis to examine the vermiform appendix for the presence of
Surgical correction of
urolithiasis caused by blockage other than within the vermiform
appendix, usually at the level of the sigmoid flexure, is a salvage
procedure with sectioning across the penis to expose the urethra
allowing slaughter several weeks later when the animal has
recovered; such surgery is not appropriate in a breeding ram. The
cost of surgery probably exceeds the eventual slaughter price such
that most sheep with urolithiasis that cannot be corrected by
removal of the vermiform appendix should be euthanased for welfare
reasons and not left to suffer any further.
Correct ration formulation
with appropriate mineralisation is the basis for prevention of
urolithiasis in intensively-reared sheep. Urine acidifiers, such as
ammonium chloride, are commonly added to rations. Sodium chloride
may be added to rations to promote water intake. Provision of
adequate roughage promotes saliva production and water
Fresh clean water must always
be available and frequent checks must be made for frozen pipes in
sub-zero temperatures during winter.
Fig 8: Checks
must be made for frozen pipes and water troughs in sub-zero
temperatures during winter.
As well as being susceptible
to copper deficiency, sheep are also prone to copper accumulation
and toxicity. There is considerable breed variation with respect to
copper absorption and therefore to copper deficiency and toxicity
with Texel and Suffolk two of the more susceptible breeds. Chronic
copper toxicity results from ingestion of relatively high levels of
copper over a prolonged period; the term "relatively high levels"
is very important as dietary factors such as molybdenum and sulphur
exert considerable influences on copper availability. During
periods of high copper intake liver copper storage increases until
critical levels are exceeded resulting in its sudden massive
release into the circulation causing destruction of red blood
cells, jaundice, and liver and kidney damage . This crisis may be
precipitated by numerous stressors including advancing pregnancy,
adverse weather, transportation, sale and housing. The
precipitation of chronic copper toxicity may occur some days to
weeks after removal of the copper source from the ration. Care is
needed when formulating a ration for rams receiving high levels of
concentrate feeding both before sale and after purchase.
Copper toxicity has been
reported in rams which have been kept in small groups by either
hobby farmers, or in rams preparing for sale or in isolation
following purchase. These rams are often kept in small paddocks
close to the farm house where wooden sheds or poultry houses have
been installed. If these sheds have recently been sprayed with a
copper preservative and excess has dripped onto the grass below,
that grass can present a danger to the sheep.
Fig 9: Dull and
inappetant Suffolk shearling ram with chronic copper poisoning.
Note the high concentrate ration.
Sheep with copper poisoning
are weak, very dull and depressed and separate from others in the
group. They have a poor appetite and often foetid diarrhoea. There
is evidence of dehydration and obvious yellowing of the eyes.
Urgent veterinary attention is essential but affected sheep have a
grave prognosis despite specific treatment.
Fig 10: Foetid
diarrhoea in a Suffolk gimmer with chronic copper
Copper toxicity may arise
following feeding cattle feed to sheep but this situation is more
common in hobby farmers. Incorrect mineral supplementation of
proprietary concentrates may occur but copper concentrations are
strictly regulated in the UK to levels below 15 mg/kg as fed in
complete feedingstuffs. The interactions of copper antagonists such
as molybdenum and sulphur are also of critical importance and
toxicity may result in certain breeds/situations where the copper
concentration is within permitted levels but these antagonists are
not included in the proprietary feed.
Inadvertent feeding of cattle concentrates to pedigree Suffolk
Acidosis (barley poisoning; grain
Acidosis results from the
sudden unaccustomed ingestion of large quantities of
carbohydrate-rich feeds, typically grain or concentrates but may
also occasionally result from a sudden change or interruption in
feeding following sale. The severity of clinical signs depends upon
the amount of grain ingested, whether the grain is rolled or whole,
and the rate of introduction of the dietary change. There may be no
diarrhoea for the first 12 to 24 hours after carbohydrate
ingestion, thereafter there is profuse foetid diarrhoea which may
contain whole grains. Affected sheep do not graze and spend long
periods lying down.
Fig 12: Acidosis
may result from the sudden unaccustomed ingestion of large
quantities of carbohydrate-rich feeds.
Fig 13: Severe
dehydration and toxaemia in a pedigree Suffolk gimmer suffering
from barley poisoning. This valuable sheep is being treated with
intravenous fluids and made a good
In most practical situations,
therapy is restricted to intravenous multivitamin injection, and
intramuscular penicillin injections to counter bacteria crossing
the compromised gut wall. Diluted oral rehydration solutions can be
given by stomach tube.
must be gradually introduced over a minimum of two weeks. If all
sheep are not coming to the feed troughs the total allocated amount
must be reduced accordingly. The grain can be diluted using sugar
beet shreds or similar feed during this acclimatisation period.
Good quality roughage must be available at all times.
Fig 14: Training
hoggs to eat concentrates. Note that few sheep are eating the rolls
on offer. The farmer has wisely restricted the amounts fed for the
first two weeks.