Stress and glycemic responses to postprandial interval and feed components in exercising horses

Six Thoroughbred geldings were used in a Latin squaredesign to determine the effects of three feeding regimens and two postprandial intervals on stress parameters during rest, exercise, and recovery. Each horse was randomly assigned to one of six treatments on six sampling days. The three feeding regimens consisted of a fasting regimen in which no feed was offered, or an isoenergetic (4.1 Mcal DE) meal of either corn or alfalfa. One or 4 h after feeding, a standardized exercise test (SET) was imposed on all horses. The SET consisted of three 10-min periods each of saddling, walking to the arena, and warm-up (walking and trotting), followed by three bouts of progressively more intense galloping at heart rates of 130–140 (10 min), 150–160 (10 min), and 170–180 bpm (5 min), respectively. Blood was sampled via jugular catheters from 0630 to 1500, including the 55-min SET. Analysis of variance by repeated measures within either the 1- or 4-h protocol showed no differences between dietary treatments for glucose concentration; differences due to sampling time were shown for concentrations of glucose, lactate, cortisol, α₁-acid glycoproteins (AGP), and the neutrophil to lymphocyte ratio (N:L). In both the 1- and 4-h protocols, glucose concentrations decreased precipitously in cornfed horses at the onset of the SET, but rebounded at the termination of the galloping. Plasma glucose concentrations in fasting and alfalfa-fed horses decreased slightly and then gradually increased throughout the SET. Serum cortisol and plasma lactate concentrations did not differ (P >.05) between dietary treatments, but increased concentrations were detected during the SET in both the 1- and 4-h protocols. The AGP concentration and N:L did not differ (P>.05) due to dietary treatments; however, AGP concentrations marginally increased (P<.10) from prefeeding to early recovery during the 1-h but not the 4-h protocol. The N:L increased (P<.05) in response to exercise; elevated values were detected in early recovery.     

MAGNETIC RESONANCE IMAGING OF CEREBRAL CORTICAL NECROSIS (POLIOENCEPHALOMALACIA) IN A DOG

A 3-year-old neutered female mixed breed dog was examined because of severe, generalized seizure activity, tetraparesis, and encephalopathic signs. Cerebrospinal fluid (CSF) evaluation was unremarkable except for a mild increase in protein. Serum and CSF titers for infectious diseases were negative. Magnetic resonance (MR) imaging examination of the brain was performed and lesions were found within the cerebral gray matter of the temporal and parietal lobes. The lesions had increased signal intensity on T1, T2, and proton density-weighted images. There was mild inhomogeneous enhancement following intravenous contrast medium administration. Neurologic status improved and the seizures were well controlled, but the dog never regained normal mentation and euthanasia was performed 10 weeks after initial evaluation. At necropsy, severe cerebral cortical necrosis was found in the regions corresponding to the lesions seen on MR imaging examination. Large numbers of fat-containing macrophages (gitter cells) were found within these areas, and are thought to be responsible for the characteristic hyperintensity seen on the MR images.     

The effect of volatile anaesthetics on the relative sensitivity of facial and distal thoracic limb muscles to vecuronium in dogs

ObjectiveTo compare n. facialis-m. nasolabialis (nF-mNL) and n. ulnar-mm. carpi flexorii (nU-mCF) sensitivity to vecuronium during halothane or isoflurane anaesthesia.Study designRandomized, prospective, experimental study.AnimalsForty-four client-owned dogs (19 male, 25 female) undergoing surgery; mean age: 5.0 years; mean body mass: 24.7 kg.MethodsThirty minutes after acepromazine (0.05 mg kg^?1) and morphine (0.5 mg kg^?1), anaesthesia was induced with intravenous (IV) thiopental and maintained with either halothane (n = 22) or isoflurane (randomly allocated) in oxygen. The lungs were mechanically ventilated and end-tidal inhaled anaesthetic (Fe’_IAA) maintained at 1.2 × MAC values. Neuromuscular transmission at nF-uNL and nU-mCF was monitored using the train of four count. Vecuronium (50 μg kg^?1 IV) was injected (t = 0) after 15 trains, 50-60 minutes after inhalational anaesthesia began, when Fe’_IAA had been constant for >15 minutes. Times of the disappearance (-) and reappearance (+) of the fourth (T4) and first twitch (T1) were recorded allowing the calculation of: latent (t = 0 to T4-) and manifest onset times (t = 0 to T1-) duration of blockade (T1- to T1+) and drug effect (T4- to T4+) and recovery time (T1+-T4+). Student’s paired t-test was used to compare simultaneous responses at nF-uNL and nU-mCF. An unpaired t-test was used to compare anaesthetic effects.ResultsLatent and manifest onset times were significantly (p < 0.05) briefer, blockade and drug effects were significantly longer and recovery from blockade were significantly slower in the nF-mNL unit in both halothane and isoflurane recipients. Profound block duration and drug action were significantly longer and recovery from blockade were significantly slower in halothane recipients at both nerve-muscle units.Conclusion and clinical relevanceThe nF-mNL was more sensitive than nU-mCF to vecuronium, particularly in halothane-anaesthetized dogs.     

Extrapituitary and Pituitary Pathological Findings in Horses with Pituitary Pars Intermedia Dysfunction: A Retrospective Study

The objective of this study was to describe the histopathologic changes observed in extrapituitary organs as well as the pituitary glands of horses with pituitary pars intermedia dysfunction (PPID). Adrenal gland, thyroid gland, liver, lung, kidney, heart, and pituitary gland from 32 horses with clinical and histologic evidence of PPID and 20 control horses were reviewed histologically. Ten of the control horses were aged animals (≥15 years), allowing those changes attributed to age to be identified. In addition to previously reported changes in adrenal gland and liver, an association was established between PPID and several extrapituitary histopathologic changes, namely bronchiolitis, proliferative glomerulopathy, and myocardial lipofuscinosis and fibrosis. The potential biologic significance of these changes is discussed and, although the retrospective design of the current study precludes establishment of causal relationships between the observed extrapituitary changes and PPID, these findings suggest that further investigations are warranted.     

Coccidioidomycosis in dogs and cats: a review

The dimorphic fungi Coccidioides immitis and Coccidioides posadasii are the causative agents of coccidioidomycosis. Dogs and cats residing in and visiting endemic areas are at risk of exposure to infectious arthrospores. The primary infection is pulmonary and frequently results in chronic cough. Disseminated disease is common and causes cutaneous, osseous, cardiac, ocular, nervous system, or other organ disease. Radiographic changes include a variable degree of interstitial pulmonary infiltration, hilar lymphadenopathy, and osseous lesions. Serological titers support the diagnosis, but definitive diagnosis relies on identification of Coccidioides in cytological or tissue samples. Coccidioidomycosis should be considered in any dog or cat that has been potentially exposed during the previous 3 years and is presented with chronic illness, respiratory signs, lameness, lymphadenopathy, nonhealing cutaneous lesions, or neurological, ocular, or cardiac abnormalities.     

Hypernatremia secondary to homemade play dough ingestion in dogs: a review of 14 cases from 1998 to 2001

Objective: To correlate the sodium chloride dosage and the serum sodium concentration to clinical signs, to determine if the dosage of homemade play dough (and, therefore, sodium chloride) is the most reliable way to predict clinical signs and prognosis, and to review previously reported treatment options. Design: Retrospective case series. Animals: Fourteen dogs with a history of homemade play dough ingestion. Procedure: Cases were examined for each animal's signalment including body weight, age, approximate amount of play dough ingested, the estimated sodium chloride dosage, clinical signs, serum sodium concentration, and outcome when available. The literature was reviewed to determine pathophysiology and treatment regimens. Results: Twelve of 14 dogs (86%) that ingested homemade play dough showed clinical signs. Vomiting (9 of 14, 64%), polydipsia, and seizures (4 of 14 each, 29%) were the most common signs followed by polyuria, tremors (3 of 14 each, 21%), and hyperthermia (2 of 14, 14%). The lowest calculated dosage associated with objective clinical signs was 1.9 g/kg. Seizures were reported in all animals with serum sodium levels greater than 180 mEq/L. Conclusions and clinical relevance: Homemade play dough ingestion can be a serious and life‐threatening problem. Many factors can contribute to the toxicity of homemade play dough. This study indicates that the serum sodium concentration is a more reliable indicator of the clinical course of the toxicity rather than the amount of play dough and, therefore, the dosage of sodium chloride ingested. Treatment should be based on a clinical evaluation of the patient and laboratory results, and consists of controlling seizures, reducing serum sodium concentrations slowly, and supportive care.