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Summary

Case records of 43 horses with pleural effusion associated with acute pleuropneumonia, chronic pleuropneumonia, or pleuritis secondary to a penetrating thoracic wound were reviewed to determine the predisposing factors, diagnosis, and treatment of this condition.

Acute pleuropneumonia was diagnosed in 36 horses, the majority of which were Thoroughbreds (89%). Of 22 (61%) horses that were in race training at the onset of illness, 11 (31%) had been recently transported a long distance and 4 (11%) had evidence of exercise-induced pulmonary hemorrhage. Physical examination findings and hematologic data were nonspecific. The most consistent abnormality was hyperfibrino-genemia. Affected horses were treated with antibiotics, thoracic drainage, nonsteroidal anti-inflammatory drugs, and supportive care. Twenty-two (61%) horses were discharged from the hospital, with the mean duration of hospitalization for those discharged being 23 days. Nine (25%) horses were euthanatized and 5 (14%) died. Bacterial culturing of thoracic fluid resulted in growth in 30 of the 36 (83%) horses. The finding of anaerobic bacteria in thoracic fluid was not associated with a lower survival rate (62%) than the overall survival rate (61%).

Four horses with chronic pleuropneumonia had a history of lethargy and inappetence for > 2 weeks. Actinobacillus equuli was isolated, either alone or in combination with other bacteria, from thoracic fluid of these 4 horses. Each horse was treated with broad spectrum antibiotics and made a rapid recovery.

Three horses with acute pleuritis secondary to penetrating thoracic wounds also had nonspecific clinical signs, apart from the wound and a large volume of pleural effusion. Bacteriologic isolates from these horses differed slightly from those of horses with acute pleuropneumonia.

Free access
in Journal of the American Veterinary Medical Association

Summary

Eight untrained 2-year-old Thoroughbred horses were used in a study of the remodeling response of the proximal sesamoid bone (psb) to training-related stimuli. Two horses each were assigned to 1 of 4 groups: group 1, untrained, pasture turnout (control); group 2, modified-classically trained, dirt track; group 3, classically trained, dirt track; and group 4, classically trained, wood chip track. Horses were given fluorochromic bone labels every 28 days during training. All horses were euthanatized after 5 months of training, and the proximal sesamoid bones (psb) were removed. A midsagittal section of bone 85- to 95- μm thick was prepared for histomorphometric analysis by use of computerized image analysis and epifluorescent microscopy. Porosity (percent), trabecular width (micrometer), extent of anisotropy (percent), mineralizing surface (percent), fractional mineralizing surface (percent), and mineral apposition rate (micrometers per day) were determined at 5 circular regions of each specimen. Region 1 was located within the apex of the psb, regions 2, 3, and 4 were subjacent to the subchondral plate, and region 5 was within the basilar articular margin. Data were pooled to allow comparison by training group and by region.

The psb from horses trained on dirt tracks (groups 2 and 3) had significantly (P < 0.05) lower porosities and greater trabecular width, compared with the control group. The psb from all training group specimens had significantly larger mineralizing surfaces than control group specimens. The fractional mineralizing surface revealed a rapid and vigorous response of the endosteal surface of the psb in horses trained on dirt tracks. When group data were pooled, region 2 was found to have the lowest porosity and greatest trabecular width of any region. Region 1 was found to have the highest porosity and lowest structural anisotropy of any region. Structural anisotropy of the cancellous bone was greatest at regions 2, 3, and 4.

The results of this study demonstrate a substantial stress adaptive remodeling response of the psb to training-related stimuli. Regional morphologic variations were found that presumably reflect the load history of the psb in vivo. Adaptive changes may allow the psb to withstand without failure large stresses generated during maximal exercise.

Free access
in American Journal of Veterinary Research

Objective—

To evaluate a protocol for subcutaneous radioiodine treatment of cats with hyperthyroidism in which the dose was determined on the basis of severity of the cat's clinical signs, thyroid tumor size, and magnitude of the serum thyroxine (T4) concentration.

Design—

Prospective case series.

Animals—

524 cats with hyperthyroidism.

Procedure—

A scoring system based on 3 factors (severity of clinical signs, size of the thyroid gland, and magnitude of the serum T4 concentration) was used to select the dose of radioiodine to be administered subcutaneously.

Results—

On the basis of the scoring system, 310 (59%) cats were treated with a low dose of radioiodine (< 3.5 mCi; median, 3.0 mCi), 158 (30%) were treated with a moderate dose (3.5 to 4.4 mCi; median, 4.0 mCi), and 56 (11 %) were treated with a high dose (≥ 4.5 mCi; median, 5.0 mCi). At time of discharge from the hospital, serum T4 concentration was still high in 80 (15.3%) cats, but by 6 months after administration of radioiodine, the serum T4 concentration had decreased to within or below reference range in all but 8 (1.5%) cats with persistent hyperthyroidism. Many cats had low serum T4 concentrations at some time after radioiodine treatment, but only 11 (2.1 %) cats developed clinical and clinicopathologic features of hypothyroidism and required supplementation with L-thyroxine. Thirteen (2.5%) cats had a relapse of hyperthyroidism 1.1 to 6.5 years after initial radioiodine treatment. Overall, the response to treatment was considered good in 94.2% of the cats. Median survival time in the cats was 2.0 years; the percentage of cats alive after 1, 2, and 3 years of treatment was 89, 72, and 52%, respectively.

Clinical Implications—

Results of the study suggest that this method of dose estimation works well and that subcutaneous administration of radioiodine provides a safe and effective means of treating hyperthyroidism in cats.

Free access
in Journal of the American Veterinary Medical Association

Summary

We reviewed the medical records of 494 cats with a variety of nonthyroidal diseases in which serum thyroxine (T4) concentration was determined as part of diagnostic evaluation. The cats were grouped by category of disease (ie, renal disease, congestive heart failure, diabetes mellitus, focal neoplasia, systemic neoplasia, hepatopathy, inflammatory bowel disease, inflammatory pulmonary disease, miscellaneous diseases, or undiagnosed disease), degree of illness (ie, mild, moderate, or severe), survival (ie, lived, died, or euthanatized), and presence or absence of a palpable thyroid gland. The mean (± sd) serum T4 concentrations in all 10 groups of cats, which ranged from 10.5 ± 11.1 nmol/L in cats with diabetes mellitus to 18.7 ± 7.8 nmol/L in cats with focal neoplasia, were significantly (P < 0.001) lower than those of normal cats (27.0 ± 10.4 nmol/L). The number of ill cats with low serum T4 concentrations (<10 nmol/L) was highest in the cats with diabetes mellitus (59%), hepatopathy (54%), renal failure (48%), and systemic neoplasia (41%). When the serum T4 concentrations in cats with mild, moderate, and severe illness were compared, mean concentrations were progressively lower (21.3 ± 6.8, 14.8 ± 8.1, and 6.5 ± 5.8 nmol/L, respectively) as degree of illness increased. Severity of illness had a more significant (P < 0.001) effect in lowering serum T4 concentrations than did disease category. Mean serum T4 concentrations in the cats that died (7.8 ± 9.8 nmol/L) or were euthanatized (10.0 ± 7.0 nmol/L) were also significantly (P < 0.001) lower than those of cats that survived (15.2 ± 8.8 nmol/L). Of the 182 cats with low serum T4 concentrations, 74 (41%) died or were euthanatized. The 63 cats with palpable thyroid nodules had significantly (P < 0.001) higher mean serum T4 concentrations (21.7 ± 10.4 nmol/L) than the cats in which a thyroid nodule was not palpated (12.7 ± 8.1 nmol/L). Adenomatous hyperplasia of the thyroid gland was confirmed at necropsy in 2 cats with a palpable thyroid gland, and 4 cats that survived have subsequently developed overt hyperthyroidism. This suggests that, in some cats with early or mild hyperthyroidism, concomitant nonthyroidal disease may suppress serum T4 concentrations into the normal range.

Free access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To examine the effects of orally administered L-lysine on clinical signs of feline herpesvirus type 1 (FHV-1) infection and ocular shedding of FHV-1 in latently infected cats.

Animals—14 young adult, FHV-1-naive cats.

Procedure—Five months after primary conjunctival inoculation with FHV-1, cats were rehoused and assigned to receive 400 mg of L-lysine in food once daily for 30 days or food only. On day 15, all cats received methylprednisolone to induce viral reactivation. Clinical signs of infection were graded, and viral shedding was assessed by a polymerase chain reaction assay throughout our study. Peak and trough plasma amino acid concentrations were assessed on day 30.

Results—Fewer cats and eyes were affected by conjunctivitis, and onset of clinical signs of infection was delayed on average by 7 days in cats receiving L-lysine, compared with cats in the control group; however, significant differences between groups were not demonstrated. Significantly fewer viral shedding episodes were identified in the treatment group cats, compared with the control group cats, after rehousing but not following corticosteroidinduced viral reactivation. Mean plasma L-lysine concentration was significantly increased at 3 hours but not at 24 hours after L-lysine administration. Plasma arginine concentration was not significantly altered.

Conclusion and Clinical Relevance—Once daily oral administration of 400 mg of L-lysine to cats latently infected with FHV-1 was associated with reduced viral shedding following changes in housing and husbandry but not following corticosteroid administration. This dose caused a significant but short-term increase in plasma L-lysine concentration without altering plasma arginine concentration or inducing adverse clinical effects. (Am J Vet Res 2003;64:37–42)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To evaluate the use of measuring plasma concentrations of atrial natriuretic peptide (ANP), B-type natriuretic peptide (BNP), and cardiac troponin-I (cTnI) to detect dogs with occult dilated cardiomyopathy (DCM).

Animals—118 client-owned dogs.

Procedures—Dogs were prospectively examined by use of ECG; echocardiography; and evaluation of concentrations of ANP, BNP, and cTnI. Occult DCM was diagnosed by evaluation of echocardiographic left ventricular dimensions and detection of ventricular arrhythmias on ECG. Sensitivity and specificity of assays for measurement of plasma concentrations of ANP, BNP, and cTnI to detect dogs with occult DCM were determined.

Results—Occult DCM was diagnosed in 21 dogs. A concentration of > 6.21 pg/mL for BNP had a sensitivity of 95.2% and specificity of 61.9% for identifying dogs with occult DCM. In contrast, concentrations of ANP and cTnI had relatively low predictive values.

Conclusions and Clinical Relevance—Blood-based screening for occult DCM in dogs can be accomplished by use of a BNP assay. Additional studies should be performed to optimize this method of screening dogs to detect occult DCM.

Full access
in American Journal of Veterinary Research
in Journal of the American Veterinary Medical Association

Summary

We measured immunoreactive (ir) plasma concentrations of the proopiomelanocortin (pomc)-derived peptides (adrenocorticotropic hormone [actch]; β-endorphin/β-lipotropin [βendlph]; and α-melanocyte stimulating hormone [αmsh]) and of cortisol in 100 clinically normal cats. Median plasma concentration of ir-acth was 2.7 pmol/L (range, ≤ 1.1 to 22 pmol/L), of βendlph was 28 pmol/L (range, 3.8 to 130 pmol/L), of αmsh was 36 pmol/L (range, ≤ 3.6 to 200 pmol/L), and of cortisol was 35 nmol/L (range, 5 to 140 nmol/L). Plasma concentrations of IR-ACTH, αmsh, and βendlph were at or below the assay sensitivity in 34, 3, and 0% of the cats, respectively. We did not detect a correlation between plasma concentrations of ir-acth and βendlph (r = 0.23) or between plasma concentrations of ir-acth and αmsh (r = 0.19). However, there was a significant (P < 0.001) correlation between plasma concentrations of irendlph and αmsh (r = 0.81). There was not a significant correlation between plasma concentration of cortisol and plasma concentration of any of the ir-pomc peptides. High plasma concentrations of irmsh and βend, pomc peptides secreted predominantly by melanotrophs in other species, indicate that clinically normal cats have an actively secreting pars intermedia. Although the βendlph assay used in this study measures the pars distalis-derived peptide β-lph, as well as βend itself, over 95% of the irendlph activity in feline plasma containing high concentrations of αmsh, but low concentrations of ir-acth, was found to coelute with human βend on gel filtration chromatography. In contrast to the high plasma concentrations of irmsh and βendlph, many cats had low to undetectable concentrations of ir-acth, a peptide secreted predominantly by pars distalis corticotrophs. The pattern of plasma pomc peptide concentrations found in cats is similar to that reported in rats, but is markedly different from that reported in dogs, in which the secretion of pars intermedia pomc peptides is normally low.

Free access
in American Journal of Veterinary Research

Summary

We evaluated the effect of ovine corticotropin-releasing hormone (crh) on plasma immunoreactive (ir) concentrations of acth, α-melanocyte-stimulating hormone, and cortisol in 8 dogs with naturally acquired adrenocortical insufficiency. Of the 7 dogs with primary adrenal insufficiency, 6 had markedly high basal plasma ir-acth concentrations and exaggerated acth responses to crh administration, whereas 1 dog that was receiving replacement doses of prednisone at the time of testing had normal basal ir-acth concentrations and a nearly normal response to crh. In contrast, the 1 dog with secondary adrenocortical insufficiency had undetectable basal plasma ir-acth concentrations, which failed to increase after administration of crh. Basal plasma α-melanocyte-stimulating hormone concentrations in the dogs with adrenal insufficiency were within normal range and were unaffected by crh administration. In all 8 dogs with adrenal insufficiency, plasma cortisol concentrations were low and did not increase after administration of crh. Therefore, stimulation with crh produced 2 patterns of plasma ir-acth response when administered to dogs with naturally acquired adrenal insufficiency. Dogs with primary adrenal insufficiency had high basal plasma ir-acth concentrations and exaggerated responses to crh, whereas the dog with secondary adrenal insufficiency had undetectable basal plasma concentrations of ir-acth that did not increase after stimulation with crh.

Free access
in American Journal of Veterinary Research