Hemodynamic Function during Neurectomy in Halothaneanesthetized Horses with or without Constant Dose Detomidine Infusion

Nine horses were premediated with acepromazine, and anesthesia was induced with guaifenesin and thiamylal. Anesthesia was maintained in four horses with halothane in oxygen, and in five horses with halothane in oxygen plus a constant dose infusion of detomidine. Both maintenance regimens produced a MAC equivalent of 1.4 at the ambient barometric pressure. Hemodynamic and respiratory measurements were made after the horses were anesthetized, during surgical manipulations involving skin or tissues other than nerves, during manipulation and transection of digital nerves, and after surgery while the limbs were being bandaged. Heart rate was significantly higher in horses anesthetized with halothane only than in horses that also received detomidine; there were no other differences in hemodynamic function or recovery characteristics. Respiratory rate was significantly higher than baseline during soft tissue and nerve manipulations; arterial blood pressure was significantly higher after surgery began and highest during neurectomy; cardiac output and cardiac index were significantly decreased during surgery; systemic vascular resistance was significantly increased during neurectomy and bandaging and highest during neurectomy. The data suggest that the increase in blood pressure often associated with surgical stimulation is caused by increased vascular resistance and may be accompanied by a decrease in cardiac output.     

The Mesh Expansion Method of Suturing Wounds on the Legs of Horses

Wound closure utilizing tension-relieving incisions located in the skin adjacent to the wound of horses was evaluated in three experiments. Healing of lower limb wounds was compared in four treatment groups; wounds sutured under tension, wounds sutured with 7 mm and 10 mm tension relieving incisions, and unsutured controls. The wounds sutured using 10 mm tension relieving incisions healed significantly faster than the other three groups (p > 0.05). The mesh expansion technique was further evaluated in four-week-old granulating wounds. The technique was found to be unsuccessful because the tension relieving incisions that were used were too small and postoperative support was inadequate. The technique was evaluated in two clinical patients, both of which had large metatarsal lacerations. Tension relieving incisions of approximately 15 mm were made and full leg walking bar casts were applied. Both wounds had healed almost completely on removal of the casts four weeks postoperatively.     

Observations on blood coagulation after snakebite in dogs and cats

Blood samples from 13 cases of snakebite, 6 in dogs and 7 in cats, were tested for activated partial thromboplastin time (APTT), prothrombin time (PT) and fibrin/fibrinogen degradation products (FDP). Four cases were tested for fibrinogen concentration. Based on the results of a commercially available ELISA test, 9 cases were caused by tiger snakes (Notechis scutatus) and 1 case by a brown snake (Pseudonaja textilis). Three other cases had clinical signs and increased creatine phosphokinase values which suggested tiger snake envenomation. Although the period post-envenomation varied, results indicated a marked prolongation of the APTT and PT in 5 of 6 dogs. Three of these 5 dogs also had increased FDP values and 3 (of 3 examined) were hypofibrinogenaemic. Clinical manifestations of this coagulopathy were: haematoma formation after venepuncture (3 cases), gingival petechiae (1 case) and hyphaema (1 case). In contrast, there was minimal or no prolongation of the APTT and PT values, and no increase in FDP, in all 7 cats. Furthermore, no cat exhibited clinical signs of a coagulopathy.     

Clinical Vignette

This 12-month-old, outdoor intact male cat (Fig. 1) was examined because of an untreated draining nasal lesion. The lesion. initially appeared as small punctures, and progressed ovcr 2 months to an ulcerated draining nodule that gradually enlarged to involve the whole muzzle, extending bilaterally to the medial canthi and having multiple drainage points through overlying necrotic skin. Results of serum feline leukemia virus antigen and feline immunodeficiency virus antibody tests were negative.     

Effect of 5 cm of Water Positive End-Expiratory Pressure on Arterial Oxygen Tension in Dogs During and After Thoracotomy

Thoracotomy in dogs often is associated with lower than expected arterial oxygen tensions (PaO₂). Pulmonary collapse from opening the thoracic cavity is likely to be responsible for decreased PaO₂ during thoracotomy. To examine whether positive end-expiratory pressure (PEEP) is beneficial to dogs undergoing thoracotomy, PaO₂ and hemoglobin saturation (SaO₂) were measured in dogs randomly assigned to receive 5 cm of H₂O PEEP (n = 7) or no PEEP (n = 9). During surgery in both groups of dogs, PaO₂ progressively decreased ( P < .001), but the decrease in PaO₂ was significantly less in the PEEP group ( P = .027). In both groups, PaO₂ did not decrease enough to have a substantial effect on SaO₂. Furthermore, application of PEEP during thoracotomy did not prevent moderate hypoxemia after surgery and discontinuation of PEEP. Application of 5 cm of H₂O PEEP seems to attenuate the decrease in PaO₂ observed in dogs undergoing thoracotomy, but routine application of PEEP does not seem justified. ©     

Pheochromocytoma Presenting as Acute Retroperitoneal Hemorrhage in a Dog

Objective: This report describes the perioperative management of a dog with a right adrenal pheochromocytoma that presented with acute retroperitoneal hemorrhage, cardiac arrhythmia and hypertension. Additionally, a summary of pheochromocytoma and the idiosyncrasies of perioperative management of a pheochromocytoma are provided.
Summary: A 7-year old male, neutered, Dalmation was presented for acute collapse, abdominal pain and tachycardia. Physical examination findings were consistent with hypoperfusion concurrent with multiple cardiac arrhythmias and hypertension. Abdominal ultrasound revealed retroperitoneal effusion and a right adrenal mass intimately associated with the caudal vena cava. Incomplete right adrenalectomy was performed. Histopathology confirmed a pheochromocytoma.
Unique information provided: To the authors' knowledge, this is the first definitive report of acute retroperitoneal hemorrhage as the initial clinical manifestation of histologically confirmed adrenal pheochromocytoma in the dog. ( J. Vet Emerg Crit Care 2001; 11(3): 221–227 )     

Arthroscopic Removal of an Osteochondral Fragment from the Middle Phalanx of a Horse

An intraarticular osteochondral chip fracture of the distal dorsolateral aspect of the right hind middle phalanx in a 4-year-old Dutch Warmblood gelding was removed arthroscopically. Accessibility and visibility of the fragment were excellent, and there was minimal soft tissue trauma.     

HYPERCALCEMIC NEPHROPATHY IN THREE DOGS: SONOGRAPHIC APPEARANCE

Persistent hypercalcemia in the dog is most commonly seen as a paraneoplastic syndrome or in association with widespread osteolytic lesions. In high concentrations calcium is a potent nephrotoxin and may cause severe and irreversible renal damage. The ultrasonographic changes in the kidneys of three dogs with hypercalcernic nephropathy are described'and compared with the changes described in the same human condition. It is suggested that ultrasound could be a useful technique for evaluation of the severity of renal damage and the potential return of renal function in such instances.     

The Effect of Storage on Ammonia Concentration in Canine Packed Red Blood Cells.

Objective: To determine the effect of storage on ammonia concentration in canine packed red blood cell (pRBC) units.
Design: In vitro and in vivo study.
Setting: University Veterinary Teaching Hospital.
Interventions: Ammonia concentration was measured in 7 units of canine pRBC prepared in citrate-phosphate-dextrose (CPD) and Adsol^a on Days 1 and 35 of storage. Ammonia was measured in 4 additional units of canine pRBC on Days 0, 7, 14, 21, 28, and 35. Plasma ammonia was also determined in 5 anemic dogs receiving pRBC.
Measurements and Main Results: Ammonia concentration increased from 73 ± 15 mmol/L (mean ± SD) on Day 1 to 800 ± 275 mmpl/L on Day (p<0.001). When measured every 7 days in 4 units of canine pRBC, ammonia concentration increased from 23 ± 8 mmol/L on Day 0 to 179 ± 13 mmol/L (Day 7), 276 ± 56 mmol/L (Day 14). 383 ± 47 mmol/L (Day21), 466 ± 30 mmol/L (Day 28), and 562 ± 27 mmol/L (Day 35) (p<0.05 for all comparisons). In a preliminary study, plasma ammonia concentration measured in blood samples from 5 anemic dogs without primary liver disease immediately before and after transfusion with 5–10 ml/kg of stored pRBC remained in the normal reference range.
Conclusions: The ammonia concentration in stored canine pRBC increased markedly with time. In this preliminary study, ammonia concentrations in dogs without primary liver disease did not increase above the reference range after transfusion with pRBC.