ISRAEL JOURNAL OF
VETERINARY MEDICINE
OUTBREAKS OF DIGITAL DERMATITIS, INTERDIGITAL DERMATITIS
AND HEEL EROSION ASSOCIATED WITH A NUTRITIONAL ETIOLOGY
Bargai U.
Koret School of Veterinary Medicine, Hebrew University, Jerusalem
Summary
Digital dermatitis is a worldwide disease of dairy cattle. The lesions are very painful
and cause clinical lameness resulting in reduction of milk production and other
economic losses. There is no agreement in the literature about the etiology of the
disease which is named differently in various publications.
Three outbreaks of digital dermatitis in dairy cattle which were circumstantially
attributed to a sudden elevation of protein in the ration are reported. The case histories
and the clinical and laboratory findings are fully described. The current nomenclature
of digital dermatitis, interdigital dermatitis and heel erosion are discussed in view of
the clinical findings. The mechanistic causation of digital dermatitis by a sudden
elevation of dietary protein is proposed.
Introduction
Digital dermatitis is a skin disorder prevalent in dairy cattle, that has been reported in
western countries, Asia and the Far East. The disease was described first in 1974 in
Italy (1), and was defined as digital dermatitis due to the inflammation of the skin
around the digit.
Since then the various forms of the inflammation that occur in this condition have
been given different names assuming them to be different disease entities (2, 3, 4).
The etiology of the disease is not agreed yet; among the etiological agents reported in
the literature are hereditary predisposition, wet soil conditions, and synergism
between environmental opportunistic bacteria (5). Several bacteriological findings in
the lesions have been described and were claimed to be the etiological agent of the
disease. For example, spirochetes of the genus Treponema were identified in tissue
sections (6,7,8).
We present here descriptions of three separate outbreaks of the disease with a similar
etiologic background associated with nutrition, a factor never previously reported as a
causative agent in the condition.
Outbreak A
A herd of dairy cattle of about 300 milking cows belonged to a kibbutz (cooperative
communal agricultural settlement) in the upper Galilee in Israel. The herd suffered for
many months from digital dermatitis at a quite constant rate during most of the winter
and spring months.
The attending veterinarian had first tried systemic antibiotic treatment for individual
sick cows. This was effective, but owing to the cost of treatment and the associated
wastage of milk, topical antibiotic treatment was tried, and was as effective as the
systemic treatment. Moreover, new cases appeared quite frequently. After many
months of new cases, the veterinarian consulted with the Koret School of Veterinary
Medicine.
A herd study disclosed that there were about 30 cows with the disease. On visiting the
herd, clinical examination revealed edema and reddish discoloration of the skin on the
dorsal aspect and above the coronary band, edema and swelling of the digital cushions
on several or all the legs, ulcerative dermatitis in the interdigital space and
proliferating keratosis of various forms over many of the digital cushions (Figures
1,2,3). The hooves of several of the affected cows were examined for evidence of subclinical laminitis but without visible evidence.
An investigation revealed that all the affected cows belonged to one specific shed and
that all were primiparous. There were 90 cows in the shed, but none of the
multiparous cows in the shed was affected. In accordance with good management, the
pregnant heifers were kept until calving in a separate shed. The ration of the heifers
contained 10% digestible protein and 1.8 Kcal metabolic energy /Kg of feed. The
nutritional investigation revealed that there was an overnight change in the diet of the
heifers housed in a separate shed. After parturition, the heifers were moved into the
shed with the high producing cows where the ration contained 18% digestible protein
and the same energy level. The digital dermatitis lesions on the legs of most of the
heifers moved in with the high lactating cows appeared within 2-3 weeks.
Blood samples were taken at random for biochemical examination from six affected
cows. It was then recommended to have a transitional period of 2-3 weeks in which
the pre-parturition diet of the heifers would be gradually changed to the lactating
cows diet. As a result new cases of digital dermatitis ceased to appear.
eel Horn Erosion with
matitis of the digital
break 1
Fig. 2.
Heel Horn ulcerative dermatitis.
Outbreak 1.
Fig. 3.
Proliferating keratitis of the
digital cushion. Outbreak 1.
Outbreak 2
Outbreak B
A consultation was requested by the attending veterinarian of a village on the Golan
Heights in northern Israel. Preliminary information revealed that there were 13 dairy
farms in the village, and the digital dermatitis had appeared in four of them. On
clinical examination of the affected cows the following lesions were found. Edema
and reddish discoloration of the skin around the coronary band, swelling of the digital
cushions of several of the legs, primarily the hind legs, ulcerative dermatitis on the
digital cushions, ulcerative dermatitis in the interdigital space and proliferative
dermatitis over the digital cushions (Figures 4, 5, 6). Several of the affected cows
were examined for sub-clinical laminitis, but none was detected.
Epidemiologic investigation revealed that the four herds involved were the only ones
where the cows were given the full recommended ration supplied by the fodder center
of the village. The other 11 herds received only part of the recommended ration and
were given a supplement from other sources and not from the fodder center. An
inquiry into the recommended ration supplied by the center revealed that it contained
24% digestible protein. The reason for the high level of the protein in the diet was that
the nutritionist-adviser to the center maintained that cows should receive a high level
of digestible protein for the first 2 months post-parturition. Blood samples were
examined from 5 cows affected with the disease and resulted in the findings shown in
Table 2. After reducing the protein level of the diet of the affected four herds to the
accepted level of 17%, new cases ceased to appear.
Fig. 5.
Hyperkeratosis of the Digital Cushion.
Outbreak 2.
Fig. 6.
Heel Horn erosion with Proliferating
dermatitis. Outbreak 2.
Outbreak C
In a village in the Jezreel Valley with dozens of dairy herds, digital dermatitis
appeared in only one herd. During the farm visit, the affected cows had the following
clinical findings; ulcerative lesions in the skin above the coronary band, interdigital
ulcerative bleeding lesions, swelling and ulcerative lesions on the digital cushions of
several legs (Figs. 7, 8).There was an additional unique lesion on several of the
affected cows with many focal discolored lesions and hemorrhages on the metatarsal
and metacarpal skin (Fig. 9).
An investigation of the nutrition of the herd revealed that the farmer had an agreement
with a nearby biscuits and wafers factory to take away every few days its broken and
reject products. The high energy, protein rich factory-waste product was fed to the
cows as part of the whole ration and put into the trough. Normally, the quantity was
small and regular, and there were no noticeable effects on the cows.About two weeks
before the dermatitis lesions appeared, the amount taken from the factory amounted to
a whole platform, weighing a few hundred kilos. The farmer was not aware of the risk
in feeding large quantities of biscuits, and had given the cows large amounts on three
successive days. At about two weeks, lesions on the skin of the lower legs had started
to appear. The interdigital lesions and the hyperkeratosis on the digital cushions
followed shortly after.
The farmer was advised to reduce the amount of biscuits in the ration and feed them
evenly. New cases did not appear.
l ulcerative dermatitis
3.
Fig. 8.
Edema and Heel Horn Erosion .
Outbreak 3.
Fig. 9.
Defuse Hemorrhages over the
skin between the Tarsi and the
fetlock Outbreak 3.
Discussion
On circumstantial evidence, the three outbreaks of digital dermatitis have one factor
in common, the association of a sudden elevation of dietary protein with the
appearance of digital dermatitis in the herds. In outbreak A, a sudden increase of
protein from 10% to 18% without any transitional period in the heifer herd was
introduced before parturition. The fact that the cases appeared mostly in winter and
spring is related to this period when most of the parturitions occur. The parturient
calvers were mixed with the group of high producing cows and were given a sudden
change in the protein concentration. In outbreak B, the very high level of dietary
protein of the high-producing cows was apparent. In outbreak C also, a sudden
increase in protein was important since biscuits and chocolate biscuits contain high
protein levels (vanilla and milk products).
In outbreaks A and B, blood samples were taken to support the clinical diagnosis. In
both most of the samples were either outside or at the upper normal range. The
laboratory findings indicated also high levels of blood albumin (Tables 1,2) In the
third outbreak, no blood samples were collected since the nutritional event had
occurred several weeks previously and there was no chance of finding biochemical
evidence.
The circumstantial evidence between the sudden increased protein level in the ration
in outbreak A, the extremely high protein level in the diet in outbreak B, and the
digital dermatitis which occurred in most of the cows, lead the author to suggest that
the sudden increase in protein should be added to the list of etiological agents of
digital dermatitis.
It is well known in medicine that the skin is very reactive to nutritional changes.
Every dermatology textbook defines urticaria as one of the first clinical sign of
nutritional allergy to a new food, and protein products are among the major causes of
urticaria. In cattle it was reported that the incidence of sole ulcer, which is a skin
lesion in the foot, is increased when cows are given high levels of protein ( 10).
The mechanism for formation of digital dermatitis by the sudden elevation of dietary
protein has yet to be investigated, but the following hypothesis is suggested. The very
high levels of protein in the diet result in abnormal levels of blood albumin. This
results in elevated osmotic pressure of the blood which in turn increases serum
transfer into the circulation, and is resolved in the body by tissue edema in the lowest
tissues in the body. In cattle it occurs with two other well known clinical signs.The
first is the acute udder edema following parturition in heifers when they start
receiving high dietary protein levels, and the second is brisket edema which also
appears post- parturition in many cows.
The digits, and especially the heels may become edematous due to plasma escaping
into the tissues. Severe tissue edema in the digital skin increases its susceptibility to
injury, followed by the entrance of bacteria such as spirochetes from the manure,.
This hypothetical mechanism can explain the reported findings of spirochetes in the
tissues of the digital cushion. This hypothesis is well substantiated by the report that
digital dermatitis could not be reproduced by merely spreading spirochetes over the
skin of the lower digit (11). It was postulated in this experiment that tissue injury must
take place before the spirochetes can gain entrance to the tissues.
Digital dermatitis is a multi-factorial disease, and the description of these outbreaks
suggests that extreme sudden elevated protein in the diet should be included in the
etiological agents of digital dermatitis.
Other interesting observations among the clinical findings of the three outbreaks, are
the presence of all three forms of digital dermatitis, heel erosion, interdigital
ulceration and digital cushion hyperkeratinization and papillomatosis, which appeared
in each of the outbreaks, in the same herd and sometimes in the same cow. The
question whether these are separate diseases or should be considered as one disease
entity under the name digital dermatitis was a subject discussed at the 10th
international symposium of diseases of the ruminants digit in Lucerne in 1998 ( 9 ).
The findings reported here support strongly that all these features should be grouped
under the original name digital dermatitis.
It is therefore suggested that one alternative is to name all these clinical features as the
digital skin disorders syndrome (D.S.D.S) as is done in many other multifactorial
diseases.
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