Trauma-induced blindness in two horses.
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Animals↗
Biomedical subjects
D R Hodgson
Publications and source records attributed to D R Hodgson.
Acute febrile diarrhoea in horses: 86 cases (1986-1991).
Eighty-six horses presented for examination at the Rural Veterinary Centre between January 1986 to December 1991 with acute diarrhoea. The average age of affected horses was 3.2 +/- 0.2 years (mean +/- SE), with 69% three years or younger. Sixty-one horses were male (36 stallions, 25 geldings) and 83 horses were Thoroughbreds (47) or Standardbreds (36). Sixty-six horses were undergoing routine training at the time of onset of diarrhoea. Eight horses were afflicted with a non-specific illness within one to five days before the onset of diarrhoea, whereas eight horses developed diarrhoea during or within 48 h of discontinuation of antimicrobial therapy. Three horses developed the diarrhoea within 24 h of road transportation. Clinically, the disorder was characterised by a fever, sudden onset of profuse diarrhoea, clinical evidence of dehydration (estimated to be 5 to 12% of body weight at the time of admission) and shock. Degenerative leucopaenia, hyponatraemia, hypochloraemia, hyperkalaemia, hyperglycaemia and azotaemia were characteristic laboratory findings. Laminitis was a sequel in about 30% of cases. The cause of diarrhoea remained undetermined in most cases. Salmonellas were isolated from faecal or tissue samples in only two cases. Similarly, there was no evidence of seroconversion to Erhlichia risticii in 17 cases. Sixty-two of the horses survived the acute phase of the disease in response to supportive care. In horses that did not survive, necropsies were performed and revealed sanguineous or turbid peritoneal fluid. The colonic and caecal walls were oedematous and thickened with serosal congestion and discolouration of these organs evident grossly.(ABSTRACT TRUNCATED AT 250 WORDS)
Acute Disease↗
Suspected traumatic rupture of the urinary bladder in an alpaca.
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Animals↗
Haematuria, pigmenturia and proteinuria in exercising horses.
The effects of exercise on urinary excretion of red blood cells, pigments (haemoglobin and myoglobin) and protein were studied in 8 mares performing treadmill exercise at speeds eliciting 40, 60 and 95% of the maximal oxygen consumption (VO2max). Gross haematuria and pigmenturia were observed in all horses during exercise at the 2 higher intensities, while these findings were detected in only one of 8 mares during exercise at 40% of the VO2max. For the remaining 7 mares exercised at 40% of the VO2max, increased urinary excretion of red blood cells (RBCs) and pigments was evident after centrifugation of urine samples and reagent strip analysis of the supernatant fractions. An increase in urine flow (UF) during exercise at 40% of the VO2max may have contributed to the infrequent observation of gross haematuria and pigmenturia during exercise at this intensity. A transient increase in UF following exercise at 60 and 95% of the VO2max resulted in rapid resolution of gross haematuria and pigmenturia, but increased urinary excretion of RBCs and pigments remained evident by reagent strip analysis for up to 60 min following exercise. Mean +/- s.e. urinary protein excretion increased from a resting value of 2.2 +/- 0.2 mg/min to 5.6 +/- 0.9, 14.5 +/- 4.7 and 78.4 +/- 18.6 mg/min after exercise at 40, 60 and 95% of the VO2max, respectively. These results demonstrate that exercise induced haematuria and pigmenturia and post exercise proteinuria are common in horses. Their occurrence is transient and does not appear to be associated with any lasting changes in renal function.
Analysis of Variance↗
The effects of tonicity, glucose concentration and temperature of an oral rehydration solution on its absorption and elimination.
Effects of different tonicities, glucose concentrations and temperatures of an oral rehydration solution (ORS) on its uptake and elimination in resting horses were studied. Fluid and electrolyte deficits similar to those occurring during prolonged exercise were induced by the administration of 1 mg/kg bwt of frusemide i.m., 3 h prior to the ORS. Fluid was administered via nasogastric tube at a volume equivalent to 4% bodyweight, which approximated diuretic induced losses. The uptake of fluid was evaluated by changes in haematocrit (PCV) and plasma total protein concentration (TP). Changes in electrolyte balance were studied by measurements of plasma and urinary electrolyte concentrations while changes in bodyweight, urine volume and faecal water content were used to estimate retention of the administered fluids. Changes in acid base status were assessed from venous blood bicarbonate values. Fluid tonicity had a major effect on the uptake and elimination of the ORS. The hypertonic fluid (628 mOsm/kg bwt) was less rapidly absorbed and resulted in more rapid fluid and electrolyte excretion than the isotonic (314 mOsm/kg bwt) and hypotonic (water) fluids. The inclusion of glucose did not enhance the absorption of the ORS, although fluids containing higher concentrations of electrolytes resulted in more rapid elimination of fluid in urine. There was a direct relationship between higher concentrations of sodium in the ORS, plasma sodium values and osmolality. Fluid temperature (5, 21 and 37 degrees C) had no demonstrable effect on absorption of the ORS and elimination of fluids post administration. We concluded that while glucose concentration and fluid temperature have minimal effects on fluid absorption and elimination, fluid tonicity was a key element in the uptake and elimination of orally administered fluid. These findings are likely to be of relevance when administering ORS in association with exercise.
Absorption↗
Equine sweat composition: effects of adrenaline infusion, exercise and training.
Significant alterations in plasma electrolyte concentrations have been reported in horses following prolonged exercise, resulting from loss of hypertonic sweat. Sweat was collected from 10 horses undergoing a 10 week training programme; 5 at moderate intensity, to speeds of 10 m/s and 5 at low intensity, to speeds of 5 m/s. Sweat was collected from 2 sites in response to a submaximal exercise test (30 min at 50% VO2max and during an adrenaline infusion (dose mean +/- s.d.; 0.3 +/- 0.05 g/kg over 30 min). Sweat samples were analysed for sodium, chloride, potassium, protein, magnesium, calcium and urea concentrations. Sweat produced in response to exercise and adrenaline infusion was hypertonic and showed no significant differences in composition following training. However, the [NaCl] of sweat rose with increased duration of sweating. Sweat produced in response to adrenaline infusion was more dilute than that produced in response to exercise, which may be related to sympathetic outflow during exercise.
Animals↗
Maximal accumulated oxygen deficit in thoroughbred horses.
Thoroughbred horses have a high aerobic capacity, approximately twice that of elite human athletes. Whereas the aerobic capacity of horses can be accurately measured, there have been no measurements of anaerobic capacity. The aim of this study was to determine whether maximal accumulated O2 deficit (MAOD) could be measured in horses and used as an estimate of anaerobic capacity, as in human athletes. Six fit Thoroughbred horses were used with the exercise protocol utilizing a treadmill set at a 10% incline. O2 uptake VO2 was measured via an open-flow system for seven submaximal speeds (3-9 m/s), and maximal VO2 (135 +/- 3 ml.kg-1.min-1) was determined. The horses performed three tests at 105 and 125% and six tests at 115% of maximal VO2. The MAOD test was performed with the treadmill accelerated rapidly from 1.5 m/s (mean acceleration time 8 s) to the calculated speed (11-14 m/s). VO2 was measured every 10 or 15 s, and the test ended when the horse no longer kept pace with the treadmill. The mean run times were 165, 98, and 57 s for intensities of 105, 115, and 125% maximal VO2. The mean MAOD values were 31 +/- 2, 30 +/- 1, and 32 +/- 2 (SE) ml O2 eq/kg for the three intensities (P > 0.05). The proportion of energy derived from aerobic and anaerobic sources was calculated from the difference between calculated O2 demand and the VO2 curve. There was no correlation between MAOD and maximal VO2.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Effect of treadmill incline and speed on metabolic rate during exercise in thoroughbred horses.
We examined the effect of treadmill speed and incline on O2 uptake (VO2), CO2 production, heart rate (HR), plasma lactate concentration, economy of locomotion, stride frequency, and stride length. A further aim was to examine the relationships between HR and VO2 and lactate and VO2 and whether these relationships vary with alterations in treadmill incline. The experiment was a latin square design, using five horses and five treadmill inclines (0, 2.5, 5.0, 7.5, and 10.0%). Fit Thoroughbred horses exercised for 4 min at 3 m/s at 0% slope, after which the treadmill was set to the allocated incline. Speeds tested ranged from 1 to 13 m/s. The relationships of VO2 and CO2 production with speed were curvilinear at 0 and 2.5% and linear at 5, 7.5, and 10% inclines. There was a linear relationship of HR and speed with a significant effect of incline. The plasma lactate concentration increased exponentially with speed, and there was a significant effect of incline. Stride length increased linearly and stride frequency increased in a curvilinear manner with speed but there was no effect of incline. There were linear relationships of HR with VO2 and HR with VO2 when expressed as percentage of maximum VO2 and maximum HR that were not affected by incline. The O2 cost of exercise on a 10% incline was approximately 2.5 times that for exercise on the flat. The strong relationship between the percentages of maximum HR and maximum VO2 indicates that over a wide range of exercise intensities the relative VO2 can be accurately predicted from measurements of HR.
Animals↗
Selective brain cooling in the horse during exercise and environmental heat stress.
Five horses were exercised on a treadmill [to central blood temperature (Tcore) approximately 42.5 degrees C]. Three of those horses were heated at rest in a climate room (53 degrees C, 90% relative humidity) (to Tcore approximately 41.5 degrees C). Temperatures were measured in the rectum, hypothalamus (Thyp), cerebrum, and cavernous sinus (Tsinus), on the skin of the head and midside, and Tcore. When Tcore increased above 38.5 degrees C, Thyp remained 0.6 +/- 0.1 degree C (SE) lower during heat exposure and 1 +/- 0.2 degrees C lower during exercise. During heat exposure, Tsinus was 2.2 +/- 0.4 degrees C below Tcore, and during exercise, Tsinus was 5 +/- 0.9 degrees C below Tcore. Upper respiratory tract bypass during exercise in one horse resulted in substantial reductions in Tcore-Thyp to 0.4 +/- 0.3 degrees C and Tcore-Tsinus to 0.9 +/- 0.2 degrees C. Thus the horse, a species without a carotid rete, can selectively cool the brain during exercise or heat exposure; this occurs, at least in part, via cool blood within the cavernous sinus, presumably resulting principally from cooling of venous blood within the upper respiratory tract.
Animals↗
Pleural effusion associated with acute and chronic pleuropneumonia and pleuritis secondary to thoracic wounds in horses: 43 cases (1982-1992).
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.
Acute Disease↗
Peritonitis associated with Actinobacillus equuli in horses: 15 cases (1982-1992).
Peritonitis attributable to Actinobacillus equuli was diagnosed in 15 horses examined at the veterinary center between 1982 and 1992. In 13 horses, historical findings included acute onset of mild to severe signs of abdominal pain, lethargy, and inappetence. Two other horses had a history of weight loss for 3 to 6 weeks prior to examination. Diagnosis was based on the physical signs and laboratory findings, including results of peritoneal fluid analysis (gross characteristics, total protein, total and differential nucleated cell counts, and morphologic findings) and culture of A equuli. Actinobacillus equuli was consistently susceptible in vitro to penicillin, trimethoprim/sulfadiazine, and aminoglycosides. All horses in the study had marked clinical improvement within 24 to 48 hours of commencing antibiotic and supportive treatment. Antibiotic treatment was continued for variable periods, depending on the horse, but ranged from 5 to 21 days. In 11 horses for which follow-up information was available, long-term response to treatment was excellent, with horses returning to original activity.
Actinobacillus↗
Gait and respiration in standardbred horses when pacing and galloping.
The relationship between gait and the respiratory response to exercise was examined in five standardbred racehorses which exercised on a treadmill at a pace and a gallop. After an initial warm-up, respiratory rate and stride frequency were measured after one and two minutes of treadmill exercise at 80 per cent of maximal oxygen consumption (VO2max), after one minute at 100 per cent VO2max and after two minutes at 100 per cent VO2max (galloping horses only). Exercise at 100 per cent VO2max continued until the horses showed signs of fatigue. Arterial blood was collected during exercise and when they were fatigued for the measurement of oxygen and carbon dioxide tensions, haemoglobin saturation and pH. Venous blood temperature was also recorded. The mean (SE) time to signs of fatigue was significantly (P < 0.05) less in the pacing horses (7.2 [0.4] minutes) than in the galloping horses (8.0 [0.4] minutes). The mean (SE) resting PCO2 was 47.7 (1.9) torr. During the pacing and galloping exercises at 80 per cent and 100 per cent VO2max the PCO2 remained in the range of 41.1 to 66.8 torr, despite concurrent hyperthermia and acidosis. The PCO2 during exercise was not significantly dependent on gait or exercise intensity. The PO2 was significantly higher in pacing horses during exercise at 80 per cent VO2max (111 [7] vs 96 [6] torr). The mean (SE) arterial blood pH decreased from 7.428 (0.025) during pacing at 5 m sec-1 to 7.250 (0.042) when the horses were fatigued.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Blood lactate disappearance after maximal exercise in trained and detrained horses.
The influence of training on blood lactate concentrations during treadmill exercise and a 40-minute inactive recovery period was examined in seven trained and seven detrained thoroughbred horses. Lactate concentrations were measured in venous blood collected at the end of each exercise state, and at intervals for 40 minutes afterwards. Measurements were made of maximum oxygen uptake (VO2max, ml kg-1 min-1), VLA4 (velocity at which blood lactate concentration was 4 mmol litre-1); LA8 (lactate concentration [mmol litre-1] during exercise at 8 m sec-1), peak lactate (highest lactate concentration after exercise), LA40 (lactate concentration 40 minutes after exercise), the time of peak lactate concentration (minutes after exercise) and the rate of disappearance of blood lactate (Rtd). The trained horses had a significantly lower LA8 (2.1 +/- 0.1 vs 6.5 +/- 1 mmol litre-1, P < 0.01), higher VLA4 (9.8 +/- 0.2 vs 5.8 +/- 0.6 m sec-1, P < 0.01) and higher VO2max (156.3 +/- 3.8 vs 107.1 +/- 3.9 ml kg-1 min-1, P < 0.001). The value of Rtd and the time of peak lactate concentration were not significantly different.
Animals↗
Management of equine sarcoids: 1975-93.
Treatment options for equine sarcoids are briefly reviewed and the results of a retrospective study of 63 cases of equine sarcoid (66 lesions) treated by clinicians from the Rural Veterinary Centre, Camden, Australia from 1975 to 1993 presented. Five different treatments were employed in the management of these 66 lesions, including surgical excision alone or in combination with cryotherapy, radiotherapy, immunotherapy and tumour transfer to a subcutaneous site on the neck. The majority of cases were treated with surgical excision alone (18/66), excision followed by cryotherapy (31/66) and immunotherapy (16/66), with success rates of 28%, 42% and 81% respectively. Success was defined as no sign of recurrence of the lesion at the time of follow-up, at least 6 months later.
Journal Article↗
The effects of an oral glucose polymer on muscle glycogen resynthesis in standardbred horses.
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Administration, Oral↗
Haemangiosarcoma in the horse: three cases.
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Animals↗
Management of mycotic keratitis in a horse using a conjunctival pedicle graft.
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Animals↗
Influence of air movement, facemask design and exercise on upper airway, transpulmonary, and transdiaphragmatic pressures in thoroughbred horses.
The influences of facial airflow, exercise and wearing a facemask on gas exchange and upper airway (Pu), transpulmonary (PTP) and transdiaphragmatic (PTD) pressures were investigated in 6 horses performing an incremental exercise test on an inclined (10%) treadmill. The test consisted of a 2 min walk followed by two 2 min exercise bouts at intensities which produced 40% and 80% of maximal oxygen consumption. Horses performed the test 4 times, once for each of 4 protocols, which involved not wearing a facemask (A), wearing a mask with either no biased flow through it (B), with an expiratory bias of 6300 L/min through it (C), or with an inspiratory bias of the same magnitude (D). Although no statistically significant differences in arterial blood gases, Pu, PTP, or PTD could be attributed to the various protocols, trends that may have been physiologically important were detected. Hypoxemia and hypercapnia associated with exercise were most marked with protocol B and least severe with protocols A or D. PTP was lowest for all tests with protocol D. Of the 3 conditions that required the wearing of a mask, protocol D was associated with the lowest Pu. While impelling air into the respiratory tract, as presumedly occurs with horses exercising over ground, may enhance respiratory function during exercise, this preliminary study does not clearly demonstrate this. Because this is an important consideration when conducting studies involving horses on treadmills, further investigations at higher exercise intensities and with additional methodologies are needed to clarify the issue.
Acid-Base Equilibrium↗