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Occurrence of lameness and digital lesions in Tanzanian goats
SmallRuminant Research, 10 (1993) 55-62
55
© 1993 Elsevier Science Publishers B.V. All rights reserved. 0921-4488/93/$06.00
Occurrence of lameness and digital lesions in Tanzanian goats M.N. Mgasa and J. Arnbjerg Institute of Clinical Studies, Department of Veterinary Radiology, Royal Veterinary and Agricultural University, Frederiksberg C, Denmark (Accepted 25 February 1992)
ABSTRACT Mgasa, M.N. and Arnbjerg, J., 1993. Occurrence of lameness and digital lesions in Tanzanian goats. Small Rumin. Res., 10: 55-62. A herd of about 200 cross bred goats from Malya farm was investigated for diseases causing lameness in the rainy and dry season. In another investigation, 1056 feet from indigenousTanzanian goats (Small East African breed) slaughtered at a local slaughterhouse in Dares Salaam were examined for lesions. In the herd survey, digital lesions accounted for 90.9% of lameness and the most frequent lesions were white line disease and foreign body (thorns) punctures in the sole which were responsible for 66.6% of lameness. The rainy season had the highest frequency of lameness compared to the dry season (P< 0.05 ). The slaughterhouse survey of feet revealed a high frequency of digital pathological changes. White line disease and dermatitis interdigitalishad the highest frequency with no differences of occurrence between seasons. Other lesions included erosio ungulae, which was recorded to be higher in the rainy season compared to the dry season. The study shows that digital lesions are among the most important causes of lameness in goats. Key words: Lameness; Digital lesions; Tanzania; Goat
INTRODUCTION
The population of goats in Tanzania is estimated to be over 6 million. The majority are indigenous types farmed by pastoralists in traditional management systems in association with crop production. Meat production is the most important function of goats as their meat is consumed widely in Tanzania, whereas milk production is low. Due to several limiting factors in the tropics their population has remained stagnant and has not kept pace with the human population increase. The demand for goat meat by far exceeds supplies, consequently, goat meat is sold at premium prices throughout the counCorrespondence to and present address: M.N. Mgasa, Faculty of Veterinary Medicine, Sokoine University of Agriculture, P.O. Box 3020, Morogoro, Tanzania.
56
M.N. MGASA AND J. ARNBJERG
try. Meat supply could be increased by employing improved production methods, identification and controlling important limiting factors (Kyomo, 1978; Devendra and Bums, 1983; Omeke, 1988; Wilson, 1988; Mtenga and Kitaly, 1990). However, disease causing lameness in goats have not been reported and fully documented. It is known that diseases causing lameness are among major constraints in sheep (West, 1983; Stewart, 1989) and cattle (Russell et al., 1982; Mortensen and Hesselholt, 1982; Whitaker et al., 1983; Choquette-Levy et al., 1985; Mgasa, 1989) production systems. There is a great need to investigate diseases causing lameness in goats. MATERIALS AND METHODS
The occurrence of lameness and digital lesions was investigated in two different categories of goats in Tanzania. In one study, a herd of blended goats (crosses between imported dairy and indigenous Tanzanian breed) at Malya Research Station (Malya farm) was investigated. The herd had 258 and 191 goats in the rainy and dry season, respectively. All goats were bred as dual purpose (for meat and milk production ). The animals were raised on natural tropical savanna grassland pastures and shrubs in fenced paddocks under a controlled grazing scheme and management. Breeding was also controlled in that males were only introduced to females during a specific breeding season. The goats were kept and grazed in three separate groups of males, females and kids. They were housed on rough concrete floored cubicles without straw bedding for the night. The floor was cleaned daily and maintained dry by adequate drainage. Occasionally, particularly during the rainy season, hoof trimming and foot bathing with 5% copper sulphate were used to control foot problems. All animals in the herd were examined clinically for lameness in the middle of the rainy (January) and dry (August) seasons. A visual examination for signs of lameness was carried out. Palpation of the feet and digits to detect abnormalities and pain was done. Examination of the digits was done before and after trimming. All animals found lame were further examined after the claws were cleaned with soapy water to ascertain the lesion causing lameness. In addition, radiography was used in special cases where abnormalities could not be ascertained by visual examination. Another investigation was conducted in a local abattoir in Dares Salaam. The abattoir draw goats from all over the country with the majority from Mwanza, Shinyanga and Dodoma regions. Goats were usually transported to the abattoir by road in trucks or railway wagons, except for a few from nearby areas which were trekked. All goats brought to this slaughterhouse were indigenous meat breeds (Small East African breed) raised under the traditional management system by pastoralists on natural grasslands and shrubs in semiarid areas. Pasturing is done throughout the year with animals being housed or kept in enclosures for the night. A total of 1056 feet samples, cut from the
OCCURRENCEOF LAMENESSAND DIGITAL LESIONS
57
metacarpal/metatarsal distally, were randomly collected and examined for digital lesions in the rainy and dry season. Feet were cleaned with water and similarly examined before and after trimming of the claws. In each season, 528 feet were examined. This group represented a cross sectional sample of the traditional meat goats in Tanzania. Data collected were analyzed by comparing relative risk ratios and chisquare test for significance of association was used in accordance with Martin etal. (1987). RESULTS
At Malya farm, a lameness frequency of 7.0 and 2.1% was recorded in the rainy and dry season, respectively. The rainy season was associated with a higher frequency of lameness than the dry season ( P < 0 . 0 5 ) . Digital lameness accounted for 90.9% in lame animals. On a comparative basis 63.6 and 31.8% of the lameness occurred in the front and hind limbs, respectively. This shows that the front limbs were more frequently affected than hind limbs (P<0.05). Percentage frequency of lameness within the three groups examined at the farm is shown in Table 1. The results show that males were more frequently lame compared to females or kids ( P < 0.05 ). Table 2 shows the lesions associated with lameness in each group. White line disease and foreign body in claws were the most frequent causes of lameness and accounted for 66.6% of the total lameness in the rainy season. H o o f overgrowth, double sole, bulb and fetlock abscess, and arthritis of the hock were among the lesions recorded in the rainy season. All occurred with equal frequency. Different types of white line lesions were recorded in lame animals during the rainy season. In three goats, underrunning of the wall in the white line TABLE 1 Lameness frequency at Malya farm, Tanzania in 1990 Item
Rainy season
Dry season
total examined
number affected
percent
total examined
number affected
percent
Females Males Kids
147 34 77
12 4 2
8.2 t 11.8 ~ 2.61
119 36 36
0 4 0
0.0 l 1.1 ~ 0.0
Total
258
18
7.0 2
191
4
2.12
1The figures indicate frequency (percent) of lameness in each group (females, males and kids), separately. 2The figures indicate the total frequency (percent) of lameness on the farm in each season.
58
M.N. MGASAAND J. ARNBJERG
with formation of hollow wall was observed. On trimming of the claw, hollow wall which was characterized by a cavity extending deep into the wall and filled with dung and dirt was observed. In two other goats, the white line appeared hollow and infected and the digit was swollen abaxially in the coronet due to inflammation. One goat was observed with a foreign body (thorn) penetrating deep into the white line, with formation of abscess. Thorns were the most frequent foreign bodies causing lameness and these were frequently observed in the sole. In most cases they were seen to penetrate deep into the sensitive laminae causing acute pain and lameness. In one long-standing case a foreign body was associated with occurrence of bulb abscess (foot abscess). In the dry season, only four animals were observed to be lame, of which three had foreign body penetration in the sole and one with fracture of the metacarpal. Several other lesions were recorded in the digits particularly in the rainy season shown in Table 3. H o o f overgrowth was seen with the highest frequency in females in the rainy season but was not observed during the dry season. It will be noted that not all the pathological changes recorded were associated with actual lameness. Although a lot of digits in the dry season were recorded with white line disease, the majority were characterized by discoloration or a superficial hollow wall without separation of the horny wall or undermining into the sensitive lamellae. These were considered as scars of a healed or healing white line disease as they were not causing lameness at the examination time. TABLE 2 Primary lesions causing lameness in the rainy and dry season (1990) at Malya farm, Tanzania, and percent frequencies of the total lame goats Rainy season M
F
Dry season K
total
Foreign body White line disease Combined lesion s Overgrowth Double sole Abscess in fetlock Bulb abscess Fracture metacarpal Arthritis hock
2 0 1 0 1 0 0 0 0
2 6 0 1 0 1 1 0 1
2 0 0 0 0 0 0 0 0
6 6 1 1 1 1 1 0 1
Total lame goats
4
12
2
18
34
147
77
258
Total examined
%
M
33.3 33.3 5.6 5.6 5.6 5.6 5.6 0.0 5.6 7.0 2 100
F
K
total
3 0 0 0 0 0 0 1 0
0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0
3 0 0 0 0 0 0 1 0
4
0
0
4
36
119
36
191
% 75.0 0.0 0.0 0.0 0.0 0.0 0.0 25.0 0.0 2.12 100
IDermatitis interdigitalis, erosio ungulae and white line disease occuring together in all four feet. 2These numbers indicate total frequency of lameness at the farm. M = Males; F = Females; K = Kids.
OCCURRENCEOF LAMENESSAND DIGITALLESIONS
59
TABLE 3 Distribution and percent frequency of digital lesions at Malya farm, Tanzania, in the total number of digits examined in each group seasonally in the year 1990 Lesion
Rainy season M (%)
Foreign body Whiteline disease Erosio ungulae Dermatitis int.dig Hoof overgrowth Double sole Soft yellow horn Haemorrhages sole Marked grooves Bulb abscess Concavity of wall Total digits examined
13 9 4 4 0 2 0 0 0 0 0
(4.8) (3.3) (1.5) (1.5) (0.0) (0.7) (0.0) (0.0) (0.0) (0.0) (0.0)
272
Dry season
F (%) 7 (0.6) 15 (1.3) 0 (0.0) 0 (0.0) 40 (3.4) 1 (0.0) 2 (0.2) 2 (0.2) 8 (0.7) 1 (0.1) 1 (0.1) 1176
K (%)
M (%)
F (%)
K (%)
3 9 0 0 0 0 0 0 0 0 0
0 8 0 0 0 0 0 0 0 0 0
0 4 0 0 0
4 (0.7) 1 (0.2) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 616
(1.0) (3.1) (0.0) (0.0) (0.0) (0.0) (0.0) (0.0) (0.0) (0.0) (0.0)
288
952
(0.0) (0.8) (0.0) (0.0) (0.0) (0.0) (0.0) (0.0) (0.0) (0.0) (0.0)
(0.0) (1.4) (0.0) (0.0) (0.0)
288
F = Females; M = Males; K = Kids. TABLE 4 The distribution of digital lesions and their frequency in the slaughter house seasonally (1990) Rainy season number affected Erosio ungulae Dermatitis int. dig. White line disease Arthritis (fetlock) Bulk abscess Hoof deformations
Dry season (%)
number affected
Total (%) (%)
66 31 50 0 2 0
(12.5) (5.9) (9.5) (0.0) (0.4) (0.0)
12 20 41 3 0 11
(2.3) (3.8) ( 7.8 ) (0.6) (0.0) (2.1)
Total affected
149
(28.3)
87
( 16.6 )
Digits examined
528
528
78 51 91 3 2 11
(7.4) (4.8) ( 8.6 ) (0.3) (0.2) (1.0)
236 ( 22.4 ) 1056
Results from the slaughterhouse investigation are shown in Table 4. Total frequency of lesions in feet examined during the rainy and dry season were 28.3 and 16.6%, respectively. This shows a higher frequency of lesions in the rainy season compared to the dry season ( P < 0 . 0 5 ) . Erosio ungulae (heel horn erosions) was observed in a relatively higher number of digits during the rainy season compared to the dry season ( P < 0 . 0 5 ) . The other lesions observed with a high frequency were dermatitis interdigitalis and white line
60
M.N. MGASA AND J. ARNBJERG
disease whose frequency did not vary significantly between the rainy and dry season ( P > 0.05 ). Dermatitis interdigitalis was characterized by superficial erosions, hyperemia and wetness in the interdigital skin. In cases of heel horn erosions, the hoof horn appeared with erosions which extended from the caudal part of the sole into the bulb area. In some claws the erosions were deep extending into the corium. White line lesions were characterized by underrunning of the hoof with wetness and in some cases pus was present in the cavity of the hollow wall abaxially. The abaxial wall was most frequently affected and in some feet extension of swelling to the coronary band was common. Arthritis of the fetlock was observed in three feet which appeared swollen from the coronet towards the fetlock with discharging fistulae in the coronary area. H o o f deformations were mainly due to hoof overgrowth resuiting in the toes markedly turning upwards (Persian slippers). Most of the lesions recorded in the slaughterhouse were more severe compared to those recorded at the farm. As only the legs from metacarpal/metatarsal area were collected from the slaughterhouse it was not possible to associate the lesions with clinical lameness. Similarly, the history, age and sex of the animals examined was not known. DISCUSSION
Heel horn erosions, white line disease and foreign body in the sole were observed with a higher frequency at Malya farm in the rainy season compared to the dry season. This shows that a moist and h u m i d environment can be associated with high frequency of these digital diseases. Similarly, footrot in goats has been described to be predisposed by m u d d y or wet pastures (Guss, 1977; Egerton, 1989). The occurrence of a higher frequency of lameness in goats at the farm during the rainy season can also be attributed to the m u d d y and wet conditions as goats were often grazed in wet pastures. Results from the slaughterhouse survey indicate that white line disease and dermatitis interdigitalis affected the goats equally in both season. The lack of difference in this group can be attributed to the selection of animals entering the slaughterhouse. In most cases animals with chronic lameness will often be selected out of herds or sold for slaughter. Furthermore, the material in the slaughterhouse was from different herds with different management and environment. The results from the slaughterhouse, therefore can not reflect the influence of season. However, it appears from the results that some of the animals entering the slaughterhouse could have been culled from their herds due to lameness. The most important environmental factor affecting lameness in the farm survey was the presence of acacia thorn bushes in the pastures. Most of the pastures where goats preferred to graze were dominated by acacia thorn bushes. A high frequency of lameness in the rainy season at the farm was due to foreign body punctures which were mainly thorns. The wet underfoot con-
OCCURRENCE OF LAMENESS AND DIGITAL LESIONS
61
ditions during the rainy season played a major role in softening the horn making it easily penetrated by thorns. Thorns penetrated deep into the sole carrying with them anaerobic bacteria which may cause infection a n d / o r abscess in deeper tissues of the claws with resulting severe lameness. This factor can be associated with the high frequency of lameness observed in the rainy season. The frequency of foreign body lameness was higher in males than in females or kids in the rainy and dry season. Similarly high incidence of foot abscesses in rams have been described to be associated to their behaviour, particularly the habit of indulging in riding and sexual activity (West, 1983 ). As a result of such activities the pasture becomes tramped and muddy. The chances of mechanical injuries and foreign body penetration in feet and digits are also increased and, therefore, the risk of infection increases. A similar situation can well explain the high frequency of lameness due to foreign body in male goats compared to the females or kids. In such cases foreign body puncture carry the infection easily deep into the horn. Furthermore, the females and kids had a much lower frequency particularly because they were often not grazed in bushy areas. In most cases they were grazed in open pasture close to the stable, while the males preferred to graze in thick bushy areas as they were not restricted. The occurrence of a high incidence of lameness in the front limbs compared to the hind limbs can also be associated with the feeding habits of goats. It is common for goats to look for young shoots at the top of bushes. In doing so, they often use the front legs for climbing the bushes while they stand on the two hind limbs. Such a posture exposes the front limbs more to mechanical injury, particularly when climbing thorn bushes which were predominant in the pastures where the goats preferred to graze. The results show that digital diseases were important problems affecting goats in both groups studied and indicates effects on health and goat production in Tanzania. However, most of the diseases recorded in this survey can be controlled by improved management. Routine prophylactic measure against digital disease such as regular hoof trimming and foot bathing are known to improve digital health in cattle (Raven, 1975 ). When such a routine is developed, several digital diseases can be detected, attended early and, therefore, improve the health status of the herd. The study also shows that lameness may be a potential economic problem in many herds and proper attention is needed. ACKNOWLEDGEMENTS
The authors are thankful to the Danish International Development Agency for funding the study. Thanks to Sokoine University of Agriculture for granting a study leave to the first author. Thanks are also due to Dr. Mphiri, Assistant Commissioner for Research and Training, Ministry of Agriculture and
62
M.N. MGASA AND J. ARNBJERG
Livestock Development, for the permission to carry out the research, to Drs. A. Basse and K. Mortensen, Institutes of Pathology and Anatomy, The Royal Veterinary and Agriculture University, Denmark for their advise and suggestions, to Dr. Msanga, officer incharge, Mwanza Veterinary Investigation Center, Dr. M.G.S. Yongolo, Malya Livestock Research Station and Mr. J. Mgasa for their help in the study.
REFERENCES Choquette-Levy, L., Baril, J., Levy, M. and St.Pierre, H., 1985. A study of foot diseases of dairy cattle in Quebec. Can. Vet. J., 26:278-281. Devendra, C. and Burns, M., 1983. Goat production in the tropics. Second edition, Commonwealth Agricultural Bureau, Farnham Royal, UK pp. 90. Egerton, J.R., 1989. Footrot of cattle, goats and deer. In: J.R. Egerton, W.K. Yong and G.G. Riffkin (Editors), Footrot and Foot Abscess of Ruminants, CRC Press, Inc., Boca, Raton, FA, pp 47-56. Guss, S.B., 1977. Management and diseases of dairy goats, Dairy Goat Journal Publishing Corp. Scottsdale, AZ. Kyomo, M.L., 1978. Meat goals in Tanzania. Ph.D. thesis, University of Dares Salaam, Tanzania, pp. 94-109. Martin, S.W., Meek, A.H. and Willeberg, P., 1987. Veterinary epidemiology, principles and methods. Iowa State University Press, Ames, pp. 124-134. Mgasa, M.N., 1989. Observations of laminitis and sole ulcers in a semi-intensively managed dairy herd in Morogoro, Tanzania. Bull. Anim. Hlth. Prod. Afric., 37."227-230. Mortensen, K. and Hesselholt, M., 1982. Laminitis in Danish dairy cattle. An epidemiological approach. Fourth international symposium on disorders of the ruminant digit. 7-10 October. Ecole Nationale veterinaire d'Alfort. France. Mtenga, L.A. and K.italy, A.J., 1990. Growth and carcass characteristics of Tanzanian goats fed Chloris gayana hay with different levels of supplementation. Small. Rumin. Res., 3: 1-8. Omeke, B.C.O., 1988. Improving goat productivity in the humid zone of the tropics. Bull. Anim. Health Prod. Afric., 36: 126-130. Raven, T.E., 1985. Cattle foot care and claw trimming. Farming Press Ltd., Ipswich, pp. 107ll3. Russell, A.M., Rowlands, G.J., Shaw, S.R. and Weaver, A.D., 1982. Survey of lameness in British dairy cattle. Vet. Rec., 11 l: 155-160. Stewart, D.J., 1989. Footrot of sheep. In: J.R. Egerton, W.K. Yong and G.G. Riffkin (Editors), Footrot and Foot Abscess of Ruminants, CRC Press, Inc. Boca Raton, FL, pp. 5-46. West, D.M., 1983. Observation of an outbreak of foot abscess in sheep. NZ Vet. J, 31 71-74. Whitaker, D.A., Kelly, J.M. and Smith, E.J., 1983. Incidence of lameness in dairy cows. Vet. Rec., 113: 60-62. Wilson, R.T., 1988. Small ruminant production systems in tropical Africa. Small Rumin. Res., l: 305-325.
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© 1993 Elsevier Science Publishers B.V. All rights reserved. 0921-4488/93/$06.00
Occurrence of lameness and digital lesions in Tanzanian goats M.N. Mgasa and J. Arnbjerg Institute of Clinical Studies, Department of Veterinary Radiology, Royal Veterinary and Agricultural University, Frederiksberg C, Denmark (Accepted 25 February 1992)
ABSTRACT Mgasa, M.N. and Arnbjerg, J., 1993. Occurrence of lameness and digital lesions in Tanzanian goats. Small Rumin. Res., 10: 55-62. A herd of about 200 cross bred goats from Malya farm was investigated for diseases causing lameness in the rainy and dry season. In another investigation, 1056 feet from indigenousTanzanian goats (Small East African breed) slaughtered at a local slaughterhouse in Dares Salaam were examined for lesions. In the herd survey, digital lesions accounted for 90.9% of lameness and the most frequent lesions were white line disease and foreign body (thorns) punctures in the sole which were responsible for 66.6% of lameness. The rainy season had the highest frequency of lameness compared to the dry season (P< 0.05 ). The slaughterhouse survey of feet revealed a high frequency of digital pathological changes. White line disease and dermatitis interdigitalishad the highest frequency with no differences of occurrence between seasons. Other lesions included erosio ungulae, which was recorded to be higher in the rainy season compared to the dry season. The study shows that digital lesions are among the most important causes of lameness in goats. Key words: Lameness; Digital lesions; Tanzania; Goat
INTRODUCTION
The population of goats in Tanzania is estimated to be over 6 million. The majority are indigenous types farmed by pastoralists in traditional management systems in association with crop production. Meat production is the most important function of goats as their meat is consumed widely in Tanzania, whereas milk production is low. Due to several limiting factors in the tropics their population has remained stagnant and has not kept pace with the human population increase. The demand for goat meat by far exceeds supplies, consequently, goat meat is sold at premium prices throughout the counCorrespondence to and present address: M.N. Mgasa, Faculty of Veterinary Medicine, Sokoine University of Agriculture, P.O. Box 3020, Morogoro, Tanzania.
56
M.N. MGASA AND J. ARNBJERG
try. Meat supply could be increased by employing improved production methods, identification and controlling important limiting factors (Kyomo, 1978; Devendra and Bums, 1983; Omeke, 1988; Wilson, 1988; Mtenga and Kitaly, 1990). However, disease causing lameness in goats have not been reported and fully documented. It is known that diseases causing lameness are among major constraints in sheep (West, 1983; Stewart, 1989) and cattle (Russell et al., 1982; Mortensen and Hesselholt, 1982; Whitaker et al., 1983; Choquette-Levy et al., 1985; Mgasa, 1989) production systems. There is a great need to investigate diseases causing lameness in goats. MATERIALS AND METHODS
The occurrence of lameness and digital lesions was investigated in two different categories of goats in Tanzania. In one study, a herd of blended goats (crosses between imported dairy and indigenous Tanzanian breed) at Malya Research Station (Malya farm) was investigated. The herd had 258 and 191 goats in the rainy and dry season, respectively. All goats were bred as dual purpose (for meat and milk production ). The animals were raised on natural tropical savanna grassland pastures and shrubs in fenced paddocks under a controlled grazing scheme and management. Breeding was also controlled in that males were only introduced to females during a specific breeding season. The goats were kept and grazed in three separate groups of males, females and kids. They were housed on rough concrete floored cubicles without straw bedding for the night. The floor was cleaned daily and maintained dry by adequate drainage. Occasionally, particularly during the rainy season, hoof trimming and foot bathing with 5% copper sulphate were used to control foot problems. All animals in the herd were examined clinically for lameness in the middle of the rainy (January) and dry (August) seasons. A visual examination for signs of lameness was carried out. Palpation of the feet and digits to detect abnormalities and pain was done. Examination of the digits was done before and after trimming. All animals found lame were further examined after the claws were cleaned with soapy water to ascertain the lesion causing lameness. In addition, radiography was used in special cases where abnormalities could not be ascertained by visual examination. Another investigation was conducted in a local abattoir in Dares Salaam. The abattoir draw goats from all over the country with the majority from Mwanza, Shinyanga and Dodoma regions. Goats were usually transported to the abattoir by road in trucks or railway wagons, except for a few from nearby areas which were trekked. All goats brought to this slaughterhouse were indigenous meat breeds (Small East African breed) raised under the traditional management system by pastoralists on natural grasslands and shrubs in semiarid areas. Pasturing is done throughout the year with animals being housed or kept in enclosures for the night. A total of 1056 feet samples, cut from the
OCCURRENCEOF LAMENESSAND DIGITAL LESIONS
57
metacarpal/metatarsal distally, were randomly collected and examined for digital lesions in the rainy and dry season. Feet were cleaned with water and similarly examined before and after trimming of the claws. In each season, 528 feet were examined. This group represented a cross sectional sample of the traditional meat goats in Tanzania. Data collected were analyzed by comparing relative risk ratios and chisquare test for significance of association was used in accordance with Martin etal. (1987). RESULTS
At Malya farm, a lameness frequency of 7.0 and 2.1% was recorded in the rainy and dry season, respectively. The rainy season was associated with a higher frequency of lameness than the dry season ( P < 0 . 0 5 ) . Digital lameness accounted for 90.9% in lame animals. On a comparative basis 63.6 and 31.8% of the lameness occurred in the front and hind limbs, respectively. This shows that the front limbs were more frequently affected than hind limbs (P<0.05). Percentage frequency of lameness within the three groups examined at the farm is shown in Table 1. The results show that males were more frequently lame compared to females or kids ( P < 0.05 ). Table 2 shows the lesions associated with lameness in each group. White line disease and foreign body in claws were the most frequent causes of lameness and accounted for 66.6% of the total lameness in the rainy season. H o o f overgrowth, double sole, bulb and fetlock abscess, and arthritis of the hock were among the lesions recorded in the rainy season. All occurred with equal frequency. Different types of white line lesions were recorded in lame animals during the rainy season. In three goats, underrunning of the wall in the white line TABLE 1 Lameness frequency at Malya farm, Tanzania in 1990 Item
Rainy season
Dry season
total examined
number affected
percent
total examined
number affected
percent
Females Males Kids
147 34 77
12 4 2
8.2 t 11.8 ~ 2.61
119 36 36
0 4 0
0.0 l 1.1 ~ 0.0
Total
258
18
7.0 2
191
4
2.12
1The figures indicate frequency (percent) of lameness in each group (females, males and kids), separately. 2The figures indicate the total frequency (percent) of lameness on the farm in each season.
58
M.N. MGASAAND J. ARNBJERG
with formation of hollow wall was observed. On trimming of the claw, hollow wall which was characterized by a cavity extending deep into the wall and filled with dung and dirt was observed. In two other goats, the white line appeared hollow and infected and the digit was swollen abaxially in the coronet due to inflammation. One goat was observed with a foreign body (thorn) penetrating deep into the white line, with formation of abscess. Thorns were the most frequent foreign bodies causing lameness and these were frequently observed in the sole. In most cases they were seen to penetrate deep into the sensitive laminae causing acute pain and lameness. In one long-standing case a foreign body was associated with occurrence of bulb abscess (foot abscess). In the dry season, only four animals were observed to be lame, of which three had foreign body penetration in the sole and one with fracture of the metacarpal. Several other lesions were recorded in the digits particularly in the rainy season shown in Table 3. H o o f overgrowth was seen with the highest frequency in females in the rainy season but was not observed during the dry season. It will be noted that not all the pathological changes recorded were associated with actual lameness. Although a lot of digits in the dry season were recorded with white line disease, the majority were characterized by discoloration or a superficial hollow wall without separation of the horny wall or undermining into the sensitive lamellae. These were considered as scars of a healed or healing white line disease as they were not causing lameness at the examination time. TABLE 2 Primary lesions causing lameness in the rainy and dry season (1990) at Malya farm, Tanzania, and percent frequencies of the total lame goats Rainy season M
F
Dry season K
total
Foreign body White line disease Combined lesion s Overgrowth Double sole Abscess in fetlock Bulb abscess Fracture metacarpal Arthritis hock
2 0 1 0 1 0 0 0 0
2 6 0 1 0 1 1 0 1
2 0 0 0 0 0 0 0 0
6 6 1 1 1 1 1 0 1
Total lame goats
4
12
2
18
34
147
77
258
Total examined
%
M
33.3 33.3 5.6 5.6 5.6 5.6 5.6 0.0 5.6 7.0 2 100
F
K
total
3 0 0 0 0 0 0 1 0
0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0
3 0 0 0 0 0 0 1 0
4
0
0
4
36
119
36
191
% 75.0 0.0 0.0 0.0 0.0 0.0 0.0 25.0 0.0 2.12 100
IDermatitis interdigitalis, erosio ungulae and white line disease occuring together in all four feet. 2These numbers indicate total frequency of lameness at the farm. M = Males; F = Females; K = Kids.
OCCURRENCEOF LAMENESSAND DIGITALLESIONS
59
TABLE 3 Distribution and percent frequency of digital lesions at Malya farm, Tanzania, in the total number of digits examined in each group seasonally in the year 1990 Lesion
Rainy season M (%)
Foreign body Whiteline disease Erosio ungulae Dermatitis int.dig Hoof overgrowth Double sole Soft yellow horn Haemorrhages sole Marked grooves Bulb abscess Concavity of wall Total digits examined
13 9 4 4 0 2 0 0 0 0 0
(4.8) (3.3) (1.5) (1.5) (0.0) (0.7) (0.0) (0.0) (0.0) (0.0) (0.0)
272
Dry season
F (%) 7 (0.6) 15 (1.3) 0 (0.0) 0 (0.0) 40 (3.4) 1 (0.0) 2 (0.2) 2 (0.2) 8 (0.7) 1 (0.1) 1 (0.1) 1176
K (%)
M (%)
F (%)
K (%)
3 9 0 0 0 0 0 0 0 0 0
0 8 0 0 0 0 0 0 0 0 0
0 4 0 0 0
4 (0.7) 1 (0.2) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 0 (0.0) 616
(1.0) (3.1) (0.0) (0.0) (0.0) (0.0) (0.0) (0.0) (0.0) (0.0) (0.0)
288
952
(0.0) (0.8) (0.0) (0.0) (0.0) (0.0) (0.0) (0.0) (0.0) (0.0) (0.0)
(0.0) (1.4) (0.0) (0.0) (0.0)
288
F = Females; M = Males; K = Kids. TABLE 4 The distribution of digital lesions and their frequency in the slaughter house seasonally (1990) Rainy season number affected Erosio ungulae Dermatitis int. dig. White line disease Arthritis (fetlock) Bulk abscess Hoof deformations
Dry season (%)
number affected
Total (%) (%)
66 31 50 0 2 0
(12.5) (5.9) (9.5) (0.0) (0.4) (0.0)
12 20 41 3 0 11
(2.3) (3.8) ( 7.8 ) (0.6) (0.0) (2.1)
Total affected
149
(28.3)
87
( 16.6 )
Digits examined
528
528
78 51 91 3 2 11
(7.4) (4.8) ( 8.6 ) (0.3) (0.2) (1.0)
236 ( 22.4 ) 1056
Results from the slaughterhouse investigation are shown in Table 4. Total frequency of lesions in feet examined during the rainy and dry season were 28.3 and 16.6%, respectively. This shows a higher frequency of lesions in the rainy season compared to the dry season ( P < 0 . 0 5 ) . Erosio ungulae (heel horn erosions) was observed in a relatively higher number of digits during the rainy season compared to the dry season ( P < 0 . 0 5 ) . The other lesions observed with a high frequency were dermatitis interdigitalis and white line
60
M.N. MGASA AND J. ARNBJERG
disease whose frequency did not vary significantly between the rainy and dry season ( P > 0.05 ). Dermatitis interdigitalis was characterized by superficial erosions, hyperemia and wetness in the interdigital skin. In cases of heel horn erosions, the hoof horn appeared with erosions which extended from the caudal part of the sole into the bulb area. In some claws the erosions were deep extending into the corium. White line lesions were characterized by underrunning of the hoof with wetness and in some cases pus was present in the cavity of the hollow wall abaxially. The abaxial wall was most frequently affected and in some feet extension of swelling to the coronary band was common. Arthritis of the fetlock was observed in three feet which appeared swollen from the coronet towards the fetlock with discharging fistulae in the coronary area. H o o f deformations were mainly due to hoof overgrowth resuiting in the toes markedly turning upwards (Persian slippers). Most of the lesions recorded in the slaughterhouse were more severe compared to those recorded at the farm. As only the legs from metacarpal/metatarsal area were collected from the slaughterhouse it was not possible to associate the lesions with clinical lameness. Similarly, the history, age and sex of the animals examined was not known. DISCUSSION
Heel horn erosions, white line disease and foreign body in the sole were observed with a higher frequency at Malya farm in the rainy season compared to the dry season. This shows that a moist and h u m i d environment can be associated with high frequency of these digital diseases. Similarly, footrot in goats has been described to be predisposed by m u d d y or wet pastures (Guss, 1977; Egerton, 1989). The occurrence of a higher frequency of lameness in goats at the farm during the rainy season can also be attributed to the m u d d y and wet conditions as goats were often grazed in wet pastures. Results from the slaughterhouse survey indicate that white line disease and dermatitis interdigitalis affected the goats equally in both season. The lack of difference in this group can be attributed to the selection of animals entering the slaughterhouse. In most cases animals with chronic lameness will often be selected out of herds or sold for slaughter. Furthermore, the material in the slaughterhouse was from different herds with different management and environment. The results from the slaughterhouse, therefore can not reflect the influence of season. However, it appears from the results that some of the animals entering the slaughterhouse could have been culled from their herds due to lameness. The most important environmental factor affecting lameness in the farm survey was the presence of acacia thorn bushes in the pastures. Most of the pastures where goats preferred to graze were dominated by acacia thorn bushes. A high frequency of lameness in the rainy season at the farm was due to foreign body punctures which were mainly thorns. The wet underfoot con-
OCCURRENCE OF LAMENESS AND DIGITAL LESIONS
61
ditions during the rainy season played a major role in softening the horn making it easily penetrated by thorns. Thorns penetrated deep into the sole carrying with them anaerobic bacteria which may cause infection a n d / o r abscess in deeper tissues of the claws with resulting severe lameness. This factor can be associated with the high frequency of lameness observed in the rainy season. The frequency of foreign body lameness was higher in males than in females or kids in the rainy and dry season. Similarly high incidence of foot abscesses in rams have been described to be associated to their behaviour, particularly the habit of indulging in riding and sexual activity (West, 1983 ). As a result of such activities the pasture becomes tramped and muddy. The chances of mechanical injuries and foreign body penetration in feet and digits are also increased and, therefore, the risk of infection increases. A similar situation can well explain the high frequency of lameness due to foreign body in male goats compared to the females or kids. In such cases foreign body puncture carry the infection easily deep into the horn. Furthermore, the females and kids had a much lower frequency particularly because they were often not grazed in bushy areas. In most cases they were grazed in open pasture close to the stable, while the males preferred to graze in thick bushy areas as they were not restricted. The occurrence of a high incidence of lameness in the front limbs compared to the hind limbs can also be associated with the feeding habits of goats. It is common for goats to look for young shoots at the top of bushes. In doing so, they often use the front legs for climbing the bushes while they stand on the two hind limbs. Such a posture exposes the front limbs more to mechanical injury, particularly when climbing thorn bushes which were predominant in the pastures where the goats preferred to graze. The results show that digital diseases were important problems affecting goats in both groups studied and indicates effects on health and goat production in Tanzania. However, most of the diseases recorded in this survey can be controlled by improved management. Routine prophylactic measure against digital disease such as regular hoof trimming and foot bathing are known to improve digital health in cattle (Raven, 1975 ). When such a routine is developed, several digital diseases can be detected, attended early and, therefore, improve the health status of the herd. The study also shows that lameness may be a potential economic problem in many herds and proper attention is needed. ACKNOWLEDGEMENTS
The authors are thankful to the Danish International Development Agency for funding the study. Thanks to Sokoine University of Agriculture for granting a study leave to the first author. Thanks are also due to Dr. Mphiri, Assistant Commissioner for Research and Training, Ministry of Agriculture and
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M.N. MGASA AND J. ARNBJERG
Livestock Development, for the permission to carry out the research, to Drs. A. Basse and K. Mortensen, Institutes of Pathology and Anatomy, The Royal Veterinary and Agriculture University, Denmark for their advise and suggestions, to Dr. Msanga, officer incharge, Mwanza Veterinary Investigation Center, Dr. M.G.S. Yongolo, Malya Livestock Research Station and Mr. J. Mgasa for their help in the study.
REFERENCES Choquette-Levy, L., Baril, J., Levy, M. and St.Pierre, H., 1985. A study of foot diseases of dairy cattle in Quebec. Can. Vet. J., 26:278-281. Devendra, C. and Burns, M., 1983. Goat production in the tropics. Second edition, Commonwealth Agricultural Bureau, Farnham Royal, UK pp. 90. Egerton, J.R., 1989. Footrot of cattle, goats and deer. In: J.R. Egerton, W.K. Yong and G.G. Riffkin (Editors), Footrot and Foot Abscess of Ruminants, CRC Press, Inc., Boca, Raton, FA, pp 47-56. Guss, S.B., 1977. Management and diseases of dairy goats, Dairy Goat Journal Publishing Corp. Scottsdale, AZ. Kyomo, M.L., 1978. Meat goals in Tanzania. Ph.D. thesis, University of Dares Salaam, Tanzania, pp. 94-109. Martin, S.W., Meek, A.H. and Willeberg, P., 1987. Veterinary epidemiology, principles and methods. Iowa State University Press, Ames, pp. 124-134. Mgasa, M.N., 1989. Observations of laminitis and sole ulcers in a semi-intensively managed dairy herd in Morogoro, Tanzania. Bull. Anim. Hlth. Prod. Afric., 37."227-230. Mortensen, K. and Hesselholt, M., 1982. Laminitis in Danish dairy cattle. An epidemiological approach. Fourth international symposium on disorders of the ruminant digit. 7-10 October. Ecole Nationale veterinaire d'Alfort. France. Mtenga, L.A. and K.italy, A.J., 1990. Growth and carcass characteristics of Tanzanian goats fed Chloris gayana hay with different levels of supplementation. Small. Rumin. Res., 3: 1-8. Omeke, B.C.O., 1988. Improving goat productivity in the humid zone of the tropics. Bull. Anim. Health Prod. Afric., 36: 126-130. Raven, T.E., 1985. Cattle foot care and claw trimming. Farming Press Ltd., Ipswich, pp. 107ll3. Russell, A.M., Rowlands, G.J., Shaw, S.R. and Weaver, A.D., 1982. Survey of lameness in British dairy cattle. Vet. Rec., 11 l: 155-160. Stewart, D.J., 1989. Footrot of sheep. In: J.R. Egerton, W.K. Yong and G.G. Riffkin (Editors), Footrot and Foot Abscess of Ruminants, CRC Press, Inc. Boca Raton, FL, pp. 5-46. West, D.M., 1983. Observation of an outbreak of foot abscess in sheep. NZ Vet. J, 31 71-74. Whitaker, D.A., Kelly, J.M. and Smith, E.J., 1983. Incidence of lameness in dairy cows. Vet. Rec., 113: 60-62. Wilson, R.T., 1988. Small ruminant production systems in tropical Africa. Small Rumin. Res., l: 305-325.