TENOSYNOVITIS OF THE DEEP DIGITAL FLEXOR TENDON IN HORSES R. W. Van Pelt, W. F. Riley, Jr. and P. J. Tillotson*

INTRODUCTION sheaths, statistical comparisons were made be- tween certain values determined for synovial TENOSYNOVITIS of the deep digital flexor ten- effusions from tarsal synovial sheaths of don (thoroughpin) in horses is manifested by affected horses and synovial fluids from the distention of its tarsal synovial sheath due to tibiotarsal of control formation of an excessive synovial effusion. Un- horses. less tenosynovitis is acute, signs of inflamma- Control Horses tion, pain or lameness are absent (1). Tendinitis Five healthy horses ranging in age from can and does occur in conjunction with inflam- four to nine years were used as controls. Four mation of the tarsal synovial sheath. of the horses were Thoroughbreds and one As tendons function they are frequently sub- horse was of Quarter Horse breeding. All jected to considerable strain, peritendinous control horses were geldings. pressure, and friction between the parietal and samples were obtained from the tibiotarsal . visceral layers of the (2). Acute direct trauma or trauma that is multiple and Hematologic Determinations minor can precipitate tenosynovitis. In acute Blood samples for determination of serum tenosynovitis of the deep digital flexor tendon, sugar content (measured as total reducing sub- the ensuing inflammatory reaction affects the stances) were obtained from the jugular vein tarsal synovial sheath, which responds to in- prior to aspiration of the tarsal synovial sheath flammation by formation of an excessive syno- in affected horses and the tibiotarsal joint in vial effusion. Chronic tenosynovitis follows the control horses. The clot was allowed to retract acute form or it can be insidious in onset. It at 50 C and the samples were then centrifuged is characterized by persistent synovial effusions, at 1,600 g at 50 C. stenosis of the tendon sheath, or adhesions be- tween the parietal and visceral layers of the Synovial Effusion Determinations tendon sheath and the enveloped tendon (6, Synovial effusion samples were transferred 8). Riziform bodies may be present in synovial from aspirating syringes to screw-capped tubes effusions in chronic tenosynovitis. which contained dried dipotassium ethylene- Therapy in this group of horses was directed diaminetetraacetatel (EDTA) in a ratio of 2 at preventing formation of excessive synovial mg of EDTA per milliliter of synovial effusion. effusion by aspiration of the tarsal synovial Synovial fluid samples from the tibiotarsal sheath and the intrathecal injection of an joints of control horses were not transferred to adrenocortical steroid or one of its synthetic tubes containing EDTA. Tests for relative analogues. Presented in this report are clinical viscosity (RV), mucinous precipitate quality, signs, response to intrathecal injection of syn- total protein content, albumin: globulin (A:G) thetic steroids, and results of synovial effusion ratio, and sugar content (measured as total analyses. Analyses of synovial effusions were reducing substances) were performed on syno- performed to characterize synovial effusions vial effusions and synovial fluids after centri- produced in horses affected with tenosynovitis fugation at 1,600 g at 50 C (5, 12, 15, 18). of the deep digital flexor tendon. Total erythrocytic and leukocytic counts were determined from noncentrifuged portions of MATERIALS AND METHODS the synovial effusion and synovial fluid samples (12). Smears for differential counts were The tarsal synovial sheaths of the deep digi- stained with Wright's stain. One hundred tal flexor tendon in eight clinically affected leukocytes were identified and counted (neu- horses were aspirated and injected with syn- trophils, lymphocytes, monocytes, macro- thetic steroids at the time of diagnostic aspira- phages, and eosinophils). tion (Table I). Since synovial fluid was unobtainable from normal synovial tendon Bacteriologic Determinations 'Department of Pathology (Van Pelt) and De- A portion of the synovial effusion sample partment of Large Animal Surgery and Medicine from two of the horses was transferred to a (Riley and Tillotson), College of Veterinary Medi- cine, Michigan State University, East Lansing, ICambridge Chemical Products, Inc., Dearborn, Mich. 48823. Mich. 35 CAN. VET. JOUR., Vol. 10, no. 9, September, 1969 a)a a) a1) Ca ci Cd C UUQ Q U Ca Ca Ca Ca a) ~a)a)00a) 0 Ca Cd 4-) U) 4-- 0) 4-J~~~)0 ~) E a)U cd 4-)4- 4) -J4- bD iO bO dd d d d 0 btO0 0

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236 TENOSYNOVITIS sterilized test tube immediately following aspi- chronically affected tarsal synovial sheaths. ration of the tarsal synovial sheath. Synovial When possible, the affected tarsal synovial effusion samples were inoculated into brain sheath was kept under a pressure bandage heart infusion2 semisolid (0.15% agar) and until resolution of excessive synovial effusion bovine blood agar plates, and incubated at 370 was achieved. C. Negative cultures were held up to 10 days. Five tarsal synovial sheaths were injected with 6 a-methylprednisolone acetate3 (40 mg / RESULTS cc) and two tarsal synovial sheaths received injections of 6 a-methyl, 17 a-hydroxyproges- Clinical Signs terone acetate4 (50 mg / cc). Excessive syno- Tenosynovitis of the deep digital flexor ten- vial effusion was controlled in a three-year-old dol was unilateFal in all horses and was mani- Standardbred gelding (Table I, horse 8) fesd by a fluctuant, palpable distention of its affected with chronic tenosynovitis of the tarsal tarsal synovial sheath. The tarsal synovial synovial sheath following the second intrathe- sheath was distended on both medial and cal injection of 30 mg of 9-fluoroprednisolone lateral sides of the tarsus; however, the great- acetate5 (2 mg / cc) and 300 mg of 6 a-methyl, est degree of distention was limited to the 17 a-hydroxyprogesterone acetate. medial aspect of the tarsus. Degree of disten- Intrathecal injection of 6 a-methyl, 17 a- tion was variable, dependent on the capacity hydroxyprogesterone acetate did not alter the of individual tarsal synovial sheaths for reten- estrous cycle of one mare or impair fertility in tion of excessive synovial effusion. Tenosyno- one stallion (Table I, horses 6 and 7). vitis was chronic in all horses at the time of clinical examination, and signs of inflammation, Synovial Effusion Findings as manifested by heat and pain on palpation, All synovial effusions from horses affected and lameness were not apparent. None of the with tenosynovitis of the deep digital flexor horses had developed adhesions between the tendon were transudative. Quantity and gross parietal and visceral layer. of the tarsal synovial appearance of synovial effusions were recorded sheath, and the tendon of the deep digital flexor. at the time of aspiration and intrathecal injec- tion (Table II). Potential capacity of indivi- Clinical Response to Intrathecal Injection dual tarsal synovial sheaths and the duration Aspiration of affected tarsal synovial sheaths of tenosynovitis determined the quantity of provided symptomatic relief from intrathecal retained excessive synovial effusion. Grossly, pressure and had a therapeutic effect by re- synovial effusions were either pale yellow and moving excessive synovial effusion. Intrathecal clear, or amber and clear, or amber and injection of synthetic steroids controlled forma- opaque in appearance. One synovial effusion tion of excessive synovial effusions in tarsal contained some flocculent material. Synovial synovial sheaths. Dosage and choice of inject- xanthochromia was more pronounced in amber able synthetic steroid in each horse was deter- synovial effusions due to continued intrathecal mined by the degree of distention of the tarsal hemorrhage and subsequent hemolysis ante- synovial sheath and the approximate duration cedent to aspiration. of the synovial effusion (Table I). Acute in- Relative viscosity and mucinous precipitate flammation was not a factor in determining quality were determined for each synovial therapeutic dosages of synthetic steroids in this effusion sample (Table III). These procedures group of horses. determined the relative viscosity of synovial Response to intrathecal injection of various effusions and, qualitatively the concentration synthetic steroids was manifested clinically by and polymerization of the hyaluronic acid resolution of excessive synovial effusion and a moiety in synovial effusions from horses concomitant reduction in distention of the affected with tenosynovitis of the deep digital affected tarsal synovial sheath. Clinically, flexor tendon. There was no significant (P > favorable response to the intrathecal injection 0.05) difference between the relative viscosity of synthetic steroids generally required from of synovial effusions from the tarsal synovial three to six weeks. Despite intrathecal injection sheaths of affected horses (RV = 2.44) and of synthetic steroids, a minor palpable periten- synovial fluids from the tibiotarsal joints of dinous fibrosis persisted to some degree in the control horses (RV = 3.72). Mucinous preci- more chronically affected tarsal synovial 3Depo-Medrol, Upjohn Company, Kalamazoo, sheaths. Advanced peritendinous fibrosis made Mich. it difficult to achieve complete reduction of 4Depo-Provera, Upjohn Company, Kalamazoo, Mich. 2Difco Laboratories, Inc., Detroit, Mich. 5Predef 2X, Upjohn Company, Kalamazoo, Mich. 237 CANADIAN VEINEAY JOURNAL

TABLE II GROSS APPEARANCE AND QUANTITY OF SYNOVIAL EFFUSIONS Affected Quantity tarsal (ml/tarsal Horse synovial Gross synovial No. sheath appearance sheath) 1 Right Pale yellow, 140.0 clear 2 Left Amber-opaque 50.0 3 Left Amber-clear 30.0 4 Left Pale yellow, 110.0 clear 5 Right Amber-opaque, 10.0 some flocculent material 6 Left Amber-opaque 24.0 7 Right Pale yellow, 70.0 clear 8 Left Pale yellow, 250.0 clear Mean 85.5 S.E. 27.9 S.E. = Standard error of the mean.

TABLE III RELATIVE VISOCITY, MUCINOUS PRECIPITATE QUALITY, TOTAL PROTEIN CONTENT, AND ALBUMIN: GLOBULIN RATIO OF SYNOVIAL EFFUSIONS Relative Mucinous Total Albumin: Horse viscosity precipitate protein globulin No. (at 37 °C) quality* (Gm/100 ml) ratio Affected horses

1 1.32 Fair ....

2 1.57 Fair ......

3 2.54 Poor ...... 4 2.07 Fair 1.25 7.33 5 2.16 Very poor 4.00 1.86 6 6.47 Very poor 2.29 1.06 7 1.81 Poor 1.70 0.83 8 1.59 Poor 2.73 2.21 Mean 2.44 2.39 2.66 S.E. 0.59 0.47 1.20 Control horses 1 3.55 Normal 1.04 5.50 2 3.91 Normal 1.57 0.31 3 2.61 Normal 1.39 1.62 4 4.54 Normal 1.54 8.06 5 3.97 Normal 1.37 1.58 Mean 3.72 1.38 3.41 S.E. 0.32 0.10 1.45 S.E. = Standard error of the mean. *Mucinous precipitate quality: normal = tight, ropy clump in a clear solution; fair = soft mass in a slightly turlbid, xanthochromic, or amber solution; poor = small, friable masses in a turbid, xantho- chromic, or amber solution; and very poor = few flecks in a very turbid, xanthochromic, or amber solution of 7 N glacial acetic acid (2.5%).

238 TENOSYNOVrrIS pitate quality ranged from fair (soft mass in a determined simultaneously (Table IV). The slightly turbid, xanthochromic, or amber solu- sugar content in synovial effusions ranged from tion) to very poor (few flecks in a very turbid, 97 mg/100 ml less than serum sugar content to xanthochromic, or amber solution) for synovial 18 mg/100 ml greater than serum sugar con- effusions from affected tarsal synovial sheaths. tent. The mean synovial effusion sugar content All synovial fluid samples from the tibiotarsal in affected horses was 40 mg/100 ml less than joints of control horses were normal (tight, their mean serum sugar content. Mean synovial ropy clump in a clear solution). Decreased effusion sugar content in horses affected with concentration and loss of polymerization in the tenosynovitis of the deep digital flexor tendon hyaluronic acid moiety in most synovial effu- was 29% less than their mean serum sugar sions was denoted by formation of small, fri- content. This difference was significant (P < able precipitates when 1 ml of synovial effusion 0.05). The mean sugar content in synowvial was added to 4 ml of a 2.5% aqueous solution effusion from tarsal synovial sheaths was sig- of 7 N glacial acetic acid (12). nificantly (P < 0.05) less than in synovial Results of total protein determinations and fluid from tibiotarsal joints. The sugar content A:G ratios partially confirmed the transudative in synovial fluid from tibiotarsal joints of con- properties of synovial effusions (Table III). trol horses ranged from 32 mg/100 ml less The mean total protein content in synovial than sugar content in serum to 12 mg/100 ml fluid from control horses (1.38 Gm/100 ml) greater than sugar content in serum. There was slightly less than in synovial effusions was a mean synovial fluid sugar difference for from affected horses (2.39 Gm/100 ml). The control horses of 9 mg/100 ml less than their mean A:G ratio (3.41) was slightly higher in mean serum sugar content. Mean synovial fluid synovial fluid from control horses than the sugar content in control horses was 4% less than mean A:G ratio (2.66) in synovial effusion their mean serum sugar content, which was not from horses affected with tenosynovitis of the significant (P > 0.10). These differences in deep digital flexor tendon. sugar content established a serum:synovial Serum and synovial effusion sugar content effusion sugar ratio of 1.4:1 for horses affected (measured as total reducing substances) were with tenosynovitis of the deep digital flexor

TABLE IV COMPARISON OF SERUM AND SYNOVIAL EFFUSION SUGAR CONTENT Serum Synovial Serum: synovial Horse sugar sugar sugar difference No. (mg/100 ml) (mg/100 ml) (mg/100 ml)* Affected horses 1 218 162 <56 2 100 105 > 5 3 105 32 <73 4 109 57 <52 [i ... 121 .... 64 82 > 18 7 94 69 <25 8 171 74 <97 Mean 123 88** <40 S.E. 20 14 16 Control horses 1 99 67 <32 2 103 105 > 2 3 65 69 > 4 4 107 100 < 7 5 138 150 > 12 Mean 102 98 < 9 S.E. 12 15 6 S.E. = Standard error of the mean. *Synovial sugar content less than or greater than the simultaneously determined serum content. **Significantly (P < 0.05) less than corresponding serum sugar content. 239 CANADIAN VETERINARY JOURNAL tendon. Serum:synovial fluid sugar ratio for tendon can be confused with tarsal hydrarth- control horses was 1:1. rosis (bog spavin) when the medioplantar and Total erythrocytic counts ranged markedly lateroplantar pouches of the tibiotarsal syno- from one synovial effusion to another (Table vial sac are visibly distended (1, 6, 16). Dis- V). There was a close relationship between tention of the tarsal synovial sheath is generally gross appearance of the synovial effusion and greatest on the medial aspect of the tarsus. In the total erythrocyte count (i.e., the highest contrast to the location of the medioplantar erythrocytic counts were in amber and clear pouch of the tibiotarsal synovial sac, the tarsal or amber and opaque synovial effusions). No synovial sheath of the deep digital flexor ten- erythrocytes were present in synovial fluid don extends 5 to 7 cm proximal to the medial from the tibiotarsal joints of control horses. malleolus of the tibia and 5 to 7 cm distal to Total leukocytic counts did not vary as mark- the proximal end of the third metatarsal bone edly as total erythrocytic counts (Table V). (10). Inflammation of the large bursa inter- Leukocytic counts for synovial fluid from con- posed between the gastrocnemius and super- trol horses were low. Increased relative num- ficial digital flexor tendons (intertendinous bers of neutrophils were associated with calcaneal bursitis) can also present a problem increased numbers of erythrocytes. Numerous in differential diagnosis (17). laked erythrocytes were noted on synovial effu- The pathogenesis of tenosynovitis of the sion smears. Many degenerated leukocytes and deep digital flexor tendon wherein excessive a few synovial intimal cells were noted, but transudative synovial effusions are formed and excluded from both total and differential leuko- persist in its tarsal synovial sheath is a poorly cytic counts. understood syndrome in the horse (1, 6, 8). Inflammation of the tendon of the deep digital Bacteriologic Findings flexor can and does occur in conjunction with The two synovial effusion samples submitted inflammation of its tarsal synovial sheath. for bacteriologic studies were negative on cul- Acute tenosynovitis can be caused by tendon ture (Table I, horses 5 and 8). strain, friction between the parietal and vis- ceral layers of the tarsal synovial sheath, peri- DIsCUSSION tendinous pressure, and acute direct trauma to the tendon of the deep digital flexor and its Tenosynovitis of the deep digital flexor ten- tarsal synovial sheath (2). Acute tenosynovitis don in horses was manifested by marked dis- of the deep digital flexor tendon is manifested tention of its tarsal synovial sheath due to by rapid filling of the tarsal synovial sheath, formation and retention of an excessive transu- heat, pain, and lameness (1). Acquired hyper- dative synovial effusion. Distention of the sensitivity to an unknown foreign agent or tarsal synovial sheath of the deep digital flexor agents can precipitate acute tenosynovitis (8). TABLE V CYTOLOGIC PROPERTIES OF SYNOVIAL EFFUSIONS Neutro- Lympho- Mono- Macro- Eosino Horse Erythrocytes Leukocytes phils cytes cytes phages phils No. (per cmm) (per cmm) (%) (%) (%) (%) (%) Affected horses 1 0 175 7 73 13 7 0 2 8,000 500 30 20 50 0 0 3 3,000 600 52 1 44 1 2 4 0 44 3 85 12 0 0 5 20,500 367 61 27 12 0 0 6 21,500 200 8 65 22 1 4 7 111 311 0 95 5 0 0 8 1,975 511 5 93 2 0 0 Mean 6,886 339 20.8 57.4 20.0 1.1 0.8 Control horses 1 0 44 0 30 64 6 0 2 0 144 2 52 40 6 0 3 0 78 4 64 26 6 0 4 0 78 0 82 18 0 0 5 0 67 0 66 31 0 3 Mean 0 82 1.2 58.8 35.8 3.6 0.6 240 TENOSYNOVrIIS Chronic tenosynovitis may follow the acute lining the tarsal synovial condition or develop from trauma that is mul- sheath as opposed to its fibrous outer layer; tiple and minor. It is possible that repeated however, the fibrous layer is usually affected subclinical strain of the tendon of the deep (6). Inflammation is not a prerequisite for for- digital flexor or inapparent trauma could de- mation and retention of excessive transudative velop into chronic tenosynovitis. Chronic teno- synovial effusions in tarsal synovial sheaths synovitis is manifested by a fluctuant distention (8). Synovial effusions from all eight horses in of the tarsal synovial sheath due to continued this investigation were chronic at the time of formation and retention of an excessive syno- aspiration; however, these synovial effusions vial effusion. Fibrosis of the parietal layer of reflected no inflammatory changes in the syno- the tarsal synovial sheath further enhances vial membranes lining these tarsal synovial chronicity. Tenosynovitis of the deep digital sheaths. Chronic tenosynovitis and insidious flexor tendon can develop in an insidious forms of tenosynovitis of the deep digital flexor manner (8). Horses in this investigation devel- tendon were indistinguishable, both clinically oped an insidious form of tenosynovitis without and by synovial effusion analyses. The primary signs of inflammation. In the absence of an difference between the two forms of tenosyno- accurate history, it proved impossible to dis- vitis being one of etiology, viz. chronic teno- tinguish between chronic tenosynovitis and the synovitis of the deep digital flexor tendon insidious form of tensynovitis. A low degree of followed the acute form of tenosynovitis, tarsal joint angulation (i.e. too straight in the whereas the insidious form of tenosynovitis de- tarsal joint) can predispose horses to tenosyno- veloped without a history or signs of previous vitis of the deep digital flexor tendon (9). injury or inflammation. Both forms of tenosyno- Aspiration of synovial effusions and intrathe- vitis were characterized by retention of self- cal injection of synthetic steroids provided a perpetuating transudative synovial effusions. palliative means of effectively controlling pro- Pathologic changes in synovial effusions of duction and retention of excessive synovial chronic tenosynovitis were similar to those in effusions, and reducing fibrosis in tarsal syno- tarsal hydrarthrosis in horses, wherein excessive vial sheaths. The mechanism is unknown transudative synovial effusions develop and whereby adrenocortical steroids or their syn- persist (16). thetic analogues suppress formation and re- Analysis of synovial effusions and interpre- tention of excessive transudative synovial tation of findings can provide an excellent effusions (13, 14). Adrenocortical steroids sup- means of differentiating between acute and press inflammation without regard to etiology chronic forms of tenosynovitis (11). If infec- or type (i.e. suppurative or nonsuppurative) tion is suspected, bacteriologic cultures of the (2, 11). Chronic tenosynovitis or the insidious synovial effusion should be performed. Since form of tenosynovitis did not respond rapidly little information is available on normal syno- to the intrathecal action of synthetic steroids. vial fluid from tendon sheaths, it must be Intrathecal injection of 6 a-methyl, 17 a- assumed that it is analogous to the synovial hydroxyprogesterone acetate suppressed for- fluid of diarthrodial joints. Pathologic changes mation of synovial effusions and revealed a in joint diseases may therefore have a corollary prolonged duration of action when compared in tenosynovitis. Synovial xanthochromia was to 6 a-methylprednisolone acetate. These data most pronounced in amber synovial effusions reflected either an intrathecal depot effect of due to continued intrathecal hemorrhage and 6 a-methyl, 17 a-hydroxyprogesterone acetate subsequent hemolysis. Grossly, pale yellow or a delayed rate of tissue inactivation. The synovial effusions from tarsal synovial sheaths addition of 9-fluoroprednisolone acetate to 6 most closely resembled normal synovial fluid a-methyl, 17 a-hydroxyprogesterone acetate from the tibiotarsal joints of control horses. in a 1:10 ratio hastened this antitransudative Relative viscosity of synovial effusions (RV effect without interfering with its prolonged = 2.44) from tarsal synovial sheaths was lower duration of activity. These results indicated than the relative viscosity of synovial fluid that 6 a-methyl, 17 a-hydroxyprogesterone (RV = 3.72) from the tibiotarsal joints of con- acetate possesses features characteristic of 11 trol horses. Despite fair, poor, or very poor p-hydroxylated, C21 acetate steroids (3, 4). mucinous precipitates (indicative of reduced Addition of the 6 a-methyl group to the pro- hyaluronic acid concentration and polymeriza- gesterone molecule enhances its biologic acti- tion), synovial effusions maintained sufficient vity. Apparently oxygen functions at C-ll, viscousness to ameliorate the deleterious effects C-17, and C-21 are not obligatory for adreno- of friction within tarsal synovial sheaths. High- cortical steroid activity (4). ly polymerized hyaluronic acid in synovial fluid Tenosynovitis implies inflammation of the is not necessary for normal joint or tendon 241 CANADIAN VETERINARY JOURNAL sheath lubrication (7). The proteins of blood erties. Pathologic changes in synovial effu- have no lubricating properties; however, a pro- sions were minor. tein moiety forms an intrinsic component of Therapeutic benefit was derived from aspira- the hyaluronic acid-protein complex. This pro- tion of all available synovial effusion. Intra- tein moiety may serve as a prosthetic group for thecal injection of 6 a-methylprednisolone adsorption of mucin onto a moving surface acetate and 6 a-methyl, 17 a-hydroxyproges- (i.e. the articular cartilages or synovial mem- terone acetate provided a palliative means of branes lining bursas and tendon sheaths). Ad- suppressing formation and retention of exces- sorption of hyaluronic acid to synovial intimal sive effusions. Results indicated that 6 a- cells lining tendon sheaths forms an essential methyl, 17 a-hydroxyprogesterone acetate had prerequisite for boundary lubrication. a prolonged duration of antitransudative activ- Serum:synovial effusion sugar ratio was ity and possessed features characteristic of 11 1.4:1 in affected horses, compared to the 1:1 ,/-hydroxylated, C21 acetate steroids. Clinical serum:synovial fluid ratio in control horses. response to intrathecal injection of synthetic Sugar levels in synovial effusions suggest that steroids was manifested by resolution of exces- the equilibrium between a bursa and blood sive synovial effusion and concomitant reduc- differs in comparison to the sugar equilibrium tion in distention of tarsal synovial sheaths. A regulated by the blood-joint barrier (11). Low palpable peritendinous fibrosis persisted to sugar levels in the absence of bacteria or some degree in all horses. marked leukocytosis are unusual in nonsuppu- rative synovial effusions in joints. The rate of sugar utilization by tendon sheaths and bursas RESUME apparently differs from that of joints. Articular Une inflammation de la synoviale du flechis- cartilages in diarthrodial joints may require seur profond des phalanges s'est manifestee higher levels of readily available sugar in the par une distention de la gaine tarsienne causee synovial fluid. par l'accumulation de synovie. Au moment de Erythrocytic and leukocytic counts in syno- l'examen clinique, l'inflammation etait chro- vial effusions from horses affected with teno- nique. On considerait comme causes predis- synovitis of the deep digital flexor tendon were posantes les efforts et les pressions sur le increased in comparison to erythrocytic and tendon, ainsi que les trauma et les frictions 'a leukocytic counts in synovial fluid from the l'interieur de la gaine tendineuse. On n'a ob- tibiotarsal joints of control horses. Amber syno- serve aucun signe d'inflammation tel que la vial effusions had the highest erythrocytic and chaleur, la douleur ou une boiterie. La cause leukocytic counts. Increased numbers of leuko- de l'affection n'a pas ete determinee. Une cytes either gained entrance to the tarsal syno- analyse physique, biochimique et cytologique vial sheath when hemorrhage occurred or du liquide synovial n'a revele que des change- migrated into tendon sheaths in response to ments pathologiques mineurs. irritation arising from the products of ery- L'aspiration de tout le liquide synovial pos- throcytic destruction (i.e. bilirubin and hemo- sible a apporte une certaine amelioration. On siderin) (11). pallia a la surproduction de synovie en injec- tant dans la gaine affectee de l'acetate de 6-x-methylprednisolone et de l'acetate de 6-x- SUMMARY AND CONCLUSIONS methyl, 17-x-hydroxyprogesterone. Les resul- tats prouverent que cette derniere substance a Tenosynovitis of the deep digital flexor ten- une action prolong6e sur la secretion de la don was manifested by distention of its tarsal synovie et, en outre, qu'elle possede des carac- synovial sheath due to formation and retention teristiques des ac6tates C21 de steroides, 11- of an excessive transudative synovial effusion. B-hydroxyle's. L'injection de steroides de syn- Tenosynovitis of the deep digital flexor tendon these provoqua la disparition de l'exces de was chronic at the time of clinical examination. synovie et, consequemment, une diminution de Tendon strain, peritendinous pressure, trauma, la distension de la gaine tarsienne. Une fibrose and intrathecal friction were considered pre- peritendineuse, decelable a la palpation, per- disposing causes. Absent were signs of inflam- sista chez tous les chevaux. mation, as manifested by heat and pain, and lameness. The cause of an insidious form of tenosynovitis of the tarsal synovial sheath of REFERENCES the deep digital flexor tendon was undeter- 1. ADAMS, 0. R. Lameness in Horses. Second mined. Synovial effusions were analyzed for Edition. Philadelphia, Pa: Lea & Febiger. their physical, biochemical, and cytologic prop- 1966. 242 TENOSYNOVIIIS

2. FINDER, J. G. and M. POST. Local Injection 10. RooNEY, J. R., W. 0. SACK and R. E. HABEL. Therapy for Rheumatic Diseases: A Practical Guide to the Dissection of the Horse. Ann Guide. J. Am. med. Ass. 172: 2021. 1960. Arbor, Mich.: Edwards Brothers, Inc. 1967. 3. GLENN, E. M., S. L. RIcHARDsON and B. J. 11. ROPES, M. W. and W. BAUER. Synovial Fluid BowmAN. Biologic Activity of 6-Alpha-Meth- Changes in Joint Diseases. Cambridge, Mass: yl Compounds Corresponding to Progesterone, Harvard University Press. 1953. 17-Alpha-Hydroxyprogresterone Acetate and 12. VAN PELT, R. W. Properties of Equine Syno- Compound S. Metabolism. 8: 265. 1959. vial Fluid. J. Am. vet. med. Ass. 141: 1051. 4. GLENN, E. M., W. L. Ma.LuiE and C. A. 1962. SCHLAGEL. Metabolic Effects of Adrenocorti- 13. VAN PELT, R. W. and W. F. RILEY, JR. Thera- costeroids in Vivo and in Vitro: Relationship peutic Management of Tarsal Hydrarthrosis to Anti-inflammatory Effects. II. Steroid Hor- (Bog Spavin) in the Horse by Intra-Articular mones. Recent Progress in Hormone Research. Injection of Prednisolone. J. Am. vet. med. Volume 19. New York. New York, N.Y: Aca- Ass. 151: 328. 1967. demic Press. 1963. 14. VAN PELT, R. W. Intra-Articular Injection of 5. GoRNALi, A. G., C. J. BARDAwILL and M. M. 6 a-Methyl, 17 a-Hydroxyprogesterone Ace- DAvm. Determination of Serum Proteins by tate in Tarsal Hydrarthrosis (Bog Spavin) in Means of the Biuret Reaction. J. biol. Chem. the Horse. J. Am. vet. med. Ass. 151: 1159. 177: 751. 1949. 1967. 6. HICKMAN, J. Veterinary Orthopaedics. Phila- 15. VAN PELT, R. W. Characteristics of Normal delphia, Pa: J. B. Lippincott Co. 1964. Equine Tarsal Synovial Fluid. Can. J. comp. 7. LINN, F. C. and E. L. RADIN. Lubrication of Med. 31: 342. 1967. Animal Joints. III. The Effect of Certain 16. VAN PELT, R. W. Tarsal Hydrarthrosis (Bog Chemical Alterations of the Cartilage and Spavin) in the Horse: Blood, Serum, and Lubricant. Arthritis Rheum. 11: 674. 1968. Synovial Fluid Findings. Am. J. vet. Res. 8. NIEBERLE, K. and P. CoHRs. Textbook of the 29: 569. 1968. Special Pathological Anatomy of Domestic 17. VAN PELT, R. W. and W. F. RILEY, JR. Trau- Animals. Revised by P. Cohrs. Translated by matic Subcutaneous Calcaneal Bursitis (Cap- R. Crawford. New York, N.Y: Pergamon ped Hock) in the Horse. J. Am. vet. med. Press. 1967. Ass. 153: 1176. 1968. 9. O'CONNOR, J. J. Dollar's Veterinary Surgery: 18. WEICHSELBAUM, T. E. An Accurate and General, Operative, and Regional. Fourth Edi- Rapid Method for the Determination of Pro- tion. London, England: Bailliere, Tindall and teins in Small Amounts of Blood, Serum, and Cox. 1956. Plasma. Am. J. cin. Path. 16: 40. 1946.

BOOK REVIEW Animal Agents and Vectors of Human Disease. As would be expected from a revised edition, Third Edition. E. C. Faust, P. C. Beaver and there are few typographical errors. The spell- R. C. Jung. Published by Lea & Febiger, ing of "species" on page 322 happens to be one Philadelphia and the Macmillan Company of noted. The illustrations are generally excellent, Canada, Toronto. 1968. 461 pages. Price including the grouped set of color plates of $12.50. amoebae and Plasmodium spp. One or two drawings are less useful, for example, a line This is the newly revised edition of an estab- drawing of a larval ascarid on page 232. lished text written principally for medical and Of the various sections, it is felt that Section public health workers. Although it is not a text IV (Arthropods as Agents and Vectors) might book of veterinary parasitology, it does hold be rearranged slightly to arrive at a more some interest for workers in the field of veter- systematic subdivision of headings. In this same inary epidemiology. It is a rather comprehen- section there are one or two common names of sive volume, covering general principles of insects given which differ from those usually parasitology followed by sections on Protozoa, attached to the species. Hehninths and Arthropods. A further section, These, however, are very minor items, and headed "Technical Aids" covers procedures the book remains a most useful volume which useful in the diagnosis of parasitic diseases. serves as an excellent reference in the field of Full author and subject indices are included. human parasitology. D. P. Gray. 243