Histology of salivary gland infarction in the dog.

Salivary gland infarction was found in two adult dogs. The main changes were ischaemic necrosis, capsular fibrosis and regenerative hyperplasia of surviving ductal epithelium. Necrosis of arterial tunica media and thrombosis were found only in the infarcted parts of the salivary glands. The lesions appeared to be confined to the salivary glands; no cause of the infarction was found.     

Squamous cell carcinoma of the equine external genitalia: a review and assessment of penile amputation and urethrostomy as a surgical treatment

A retrospective analysis was performed on 48 cases of suspected neoplasia involving the equine external genitalia. Forty nine squamous cell carcinomata (SCC) and 23 squamous papillomata (SP) were identified. Two cases of epithelial hyperplasia and one case of habronemiasis were also recognised histopathologically. The glans penis was the most common site of tumour development accounting for 53 per cent of cases of SCC and 61 per cent of SP. The urethral diverticulum, urethral process or urethra was involved in 27.6 per cent (8/29) of cases of SCC. Twelve per cent (5/41) of cases of SCC were confirmed to have metastatic involvement of the local lymph nodes. Papillomata showing pre-malignant changes were identified in five cases. Seventy five per cent (36/48) of the animals presented were ponies. All were geldings, mean age 16.5 years. Penile amputation and urethrostomy, preputial ablation and proximal urethrostomy or local excision were used in the surgical management of these animals; three cases were inoperable and destroyed at presentation. Oedema, haemorrhage and stenosis of the urethrostomy site were encountered as post operative complications. Sixty six per cent (6/9) of animals with SCC of the glans penis (without urethral involvement), which had a known history over the follow up period, treated by penile amputation and urethrostomy survived for longer than 18 months. Similarly, of those with urethral involvement only 28.6 per cent (2/7) survived for a similar follow-up period. SCC not uncommonly affects the external genitalia of aged pony geldings and frequently the glans penis. If the lesion is identified before local metastasis occurs, penile amputation and urethrostomy is indicated and the prognosis is favourable.     

LIVER METABOLISM DURING MALIGNANT HYPERTHERMIA IN THE PIETRAIN PIG

Liver function was systematically investigated in 7 malignant hyperthermia (MH) susceptible Pietrain pigs (mean weight 67 kg ± 7 kg SEM) to determine the contribution of hepatic metabolism to circulating substrates (Hall, Lucke, Lovell and Lister 1978). It was considered that the progressive lactic acidosis observed in MH may be a result, not only of impaired hepatic uptake of lactate but also production of lactate by the liver as is said to occur in Type II lactic acidosis (Cohen and Simpson 1975). These authors suggested that as the enzyme pyruvate decarboxylase is pH sensitive, and because it is rate limiting in the gluconeugenic pathway of lactate to glucose, under conditions of severe acidosis (pH 7.1) hepatic lactate uptake will be inhibited and there will be production of lactate by the liver. Pigs were prepared with hepatic vein, right ventricle and common carotid artery cannulae. Control measurements were made before inducing MH by ventilating with 1% halothane for 10 minutes together with intravenous injection of 1 mg suxamethonium chloride per kg body weight. Paired arterial and hepatic venous samples were collected at 10 minute intervals for the following estimations: pH, oxygen content, glucose, potassium, lactate, pyruvate, alanine, free fatty acids and glycerol. Hepatic blood flow was estimated by continuous infusion of Indocyanine green (Lucke and Hall 1978). All pigs developed MH with a rise in mean muscle temperature from 37.8°C to 41.5°C after 40 minutes. Mean hepatic blood flow decreased to 25% of control value but, because there was a concomitant increase in oxygen extraction by the liver, hepatic oxygen consumption did not change significantly. At 20 minutes after MH there was a 7-fold increase in glucose efflux from the liver with an arterial glucose concentration of 12.6 mmol/1. There was a massive efflux of 1.1 mmol K+/min early in the response showing that the characteristic hyperkalaemia is not only due to potassium loss from muscle but mainly hepatic in origin. The mean lactate uptake by the liver increased from the control 0.21 mmol/min to 1.19 mmol/min after 10 minutes MH. Even in the presence of gross acidosis (mean pH 6.75) and hepatic blood flow 25% of control, hepatic lactate uptake was still 3 times that recorded in the resting state. It is important to note, however, that although hepatic lactate uptake was increased under these conditions, it was still insufficient in the presence of gross muscle stimulation with a mean arterial lactate concentration of 19.3 mmol/l. It is concluded that the lactic acidosis in porcine MH is due to peripheral overproduction with some impairment of hepatic uptake. The gluconeugenic capacity of the liver was never completely inhibited despite the severity of the metabolic acidosis and hyperthermia and at no stage was there production of lactate by the liver.     

Developmental cysts in the upper neck of Anglo-Nubian goats

Five young Anglo-Nubian goats were found to have developed a fluid-filled cyst in the upper neck. In each case the cyst was unilateral and after excision was found to be lined in most sites by non-ciliated, pseudostratified columnar epithelium, containing goblet cells. This epithelium closely resembled that of normal parotid salivary gland ducts. The lesions did not recur in any of the four goats followed-up after surgery.     

An immunohistological study of feline glomerulonephritis using the peroxidase-antiperoxidase method

Twenty-two cases of feline glomerulonephritis were investigated for the presence of immune complexes within the glomerulus using the peroxidase-antiperoxidase (PAP) method. This method was used with formalin-fixed paraffin-wax embedded tissues which were pretreated with trypsin and with frozen sections of kidney tissue. Of a total of 25 kidney specimens examined (two cats had repeated biopsies) the composition of the deposits was 23/25 IgG, 17/25 C3, 11/25 IgM and 2/25 IgA. Serial studies of two cats showed a progression of the disease from initial nephrotic syndrome to chronic renal failure. With the more severe form of the disease there was a tendency for the deposition of complement and more than one class of immunoglobulin within the glomeruli.     

Melanocytic neoplasia in the cat

Clinical features and histopathological details from 13 cases of melanocytic neoplasia in the cat are presented. The series includes cases of intraocular melanoma (n=5), limbal melanoma (n=2), dermal melanoma (n=5) and one case of metastatic melanoma for which a primary site was not identified. In the case of the intraocular tumours, there was apparent correlation between the degree of cellular pleomorphism, the mitotic rate and the extent of local infiltration. Such an association was not identified for the melanomas arising from the limbus or skin.     

Assessment of postoperative pain after unilateral mastectomy using two different surgical techniques in dogs

Background

There are few studies reporting pain and postoperative analgesia associated with mastectomy in dogs. The aim of this study was to evaluate postoperative pain after unilateral mastectomy using two different surgical techniques in the dog.

Findings

Twenty female dogs were assigned (n=10/group) to undergo unilateral mastectomy using either the combination of sharp and blunt dissection (SBD) or the modified SBD (mSBD) technique, in which the mammary chain is separated from the abdominal wall entirely by blunt (hand and finger) dissection except for a small area cranial to the first gland, in a prospective, randomized, clinical trial. All dogs were premedicated with intramuscular acepromazine (0.05 mg/kg) and morphine (0.3 mg/kg). Anesthesia was induced with intravenous ketamine (5 mg/kg) and diazepam (0.25 mg/kg), and maintained with isoflurane. Subcutaneous meloxicam (0.2 mg/kg) was administered before surgery. Postoperative pain was evaluated according to the University of Melbourne pain scale (UMPS) by an observer who was blinded to the surgical technique.. Rescue analgesia was provided by the administration of intramuscular morphine (0.5 mg/kg) if pain scores were >14 according to the UMPS. Data were analyzed using t-tests and ANOVA (P>0.05). There were no significant differences between the groups for age, weight, extubation time, and duration of surgery and anesthesia (P>0.05). There were no significant differences for postoperative pain scores between groups. Rescue analgesia was required in one dog in each group.

Conclusions

The two surgical techniques produced similar surgical times, incidence of perioperative complications and postoperative pain. Multimodal analgesia is recommended for treatment of postoperative pain in dogs undergoing unilateral mastectomy.