Iatrogenic symptomatic hypoadrenocorticism after treatment with trilostane for hyperadrenocorticism in dogs: eight cases (2008-2019)

OBJECTIVES

Trilostane is the medical treatment of choice for hyperadrenocorticism. Iatrogenic hypoadrenocorticism is thought to be rare, with most cases being transient and only a few cases of permanent hypoadrenocorticism have been reported. This study reports findings from eight cases of iatrogenic hypoadrenocorticism and examines the presence of concurrent diseases at the time of diagnosis.

MATERIALS AND METHODS

Medical records of dogs treated for hyperadrenocorticism with trilostane since 2008 were reviewed, and cases of clinical iatrogenic hypoadrenocorticism were extracted. Cases were considered permanent if long-term replacement therapy was required.

RESULTS

Eight dogs met the inclusion criteria. The time between the beginning of trilostane treatment and the diagnosis of hypoadrenocorticism ranged from 4 days to 13 months, and the dosage of trilostane ranged between 1 and 8 mg/kg/day. Six dogs had a suspicion of concurrent disease at the time of hypoadrenocorticism diagnosis. The trilostane dose was decreased in two dogs; trilostane was withdrawn in one case without further relapse of hyperadrenocorticism; and glucocorticoids with or without mineralocorticoid supplementation were prescribed in five dogs. Two of these five dogs were lost to follow-up, and the other three had a diagnosis of permanent hypoadrenocorticism. Adrenal gland ultrasonography in these three dogs showed a progressive reduction in gland sizes with heterogeneous echogenicity.

CLINICAL SIGNIFICANCE

Iatrogenic hypoadrenocorticism is a rare but potentially life-threatening complication of trilostane treatment in dogs with hyperadrenocorticism. The occurrence of a concurrent disease might trigger the development of clinical signs of hypoadrenocorticism in previously subclinical dogs.

Congenital duodenocolic fistula in a dog

A one-year-old female cocker spaniel presented with a 6-month history of persistent diarrhoea. Abdominal ultrasonographic examination revealed mild diffuse thickening of the intestinal wall coupled with mesenteric lymphadenopathy. A connection between the duodenum and the colon was observed during an endoscopic procedure and confirmed by computed tomography. Surgical resection of the communication allowed remission of the diarrhoea. Histology showed a normal duodenal epithelium and muscular layer. A duodenocolic fistula is an abnormal connection within the digestive tract, which in humans is usually considered a complication of a local pathological condition. Due to the absence of a predisposing cause and, in view of the dog's age and histological results, a congenital origin was suspected.

Focal intestinal lipogranulomatous lymphangitis in 10 dogs

OBJECTIVES

To describe the clinical and pathological features of canine focal lipogranulomatous lymphangitis, to evaluate its underlying infectious cause and to compare it with human Crohn's disease.

METHODS

Retrospective review of case records with a histopathological diagnosis of focal lipogranulomatous lymphangitis. Bacterial and fungal colonisation was evaluated using fluorescence in situ hybridisation and histochemical staining, respectively. A comparison with Crohn's disease was performed by a human pathologist.

RESULTS

Ten dogs were evaluated. The historical complaints were predominantly chronic diarrhoea (10/10) and vomiting (5/10). The biochemical abnormalities included hypoalbuminaemia (6/10) and hypocobalaminaemia (4/6). Abdominal sonography revealed a thickened distal ileum±ileocolic junction. Colonoscopy showed a swollen caecal ostium and oedematous caecum in 7/10 dogs. A stenotic ileo-colic opening prevented endoscopic intubation in all dogs. Histology from the resected lesions revealed granulomatous inflammation involving the muscularis and serosa. Fluorescence in situ hybridization demonstrated invasive bacteria in 2/10 dogs. Post-resection, all dogs received metronidazole and tapering immunosuppressive doses of prednisolone. Remission (median 17 months) was achieved in 8/10 dogs.

CLINICAL SIGNIFICANCE

Focal lipogranulomatous lymphangitis is a rare and severe form of canine inflammatory bowel disease with preferential localisation to the ileum and the ileocolic junction. An underlying infectious aetiology was not identified.

Prevalence of physiological heart murmurs in a population of 95 healthy young adult dogs

OBJECTIVES

To determine the prevalence of physiological heart murmurs in healthy young adult dogs.

MATERIALS AND METHODS

Healthy dogs aged between 1 and 5 years were enrolled prospectively. All participating dogs underwent physical examination, urinalysis, blood testing and blood pressure measurement. Cardiac auscultations were performed by three independent examiners. Dogs with heart murmurs underwent echocardiography, to exclude cardiovascular abnormalities.

RESULTS

Of 109 dogs evaluated, 95 completed the study. Heart murmurs were detected in 22 dogs. Interobserver agreement for murmur detection was moderate to fair (weighted kappa 0 · 29-0 · 56). On the basis of two different sets of echocardiographic criteria, physiological heart murmurs were diagnosed in 6 and 11 dogs, respectively, giving a prevalence of 6-12%. All physiological heart murmurs were systolic and low-grade (I-III/VI). Most were louder towards the left heart base and some radiated up to the thoracic inlet. The epidemiological features of dogs with physiological heart murmurs did not differ significantly from those of dogs without murmurs (P > 0 · 10).

CLINICAL SIGNIFICANCE

This study shows that physiological heart murmurs may not be limited to growing dogs or specific breeds, as they were commonly encountered in this population of healthy young adult dogs.

Atypical forms of canine leishmaniosis

Canine leishmaniosis is a common disease in the Mediterranean area, but sporadic cases in dogs having travelled through endemic regions are also reported. The disease's evolution is usually chronic and symptoms are either non-specific (fever, weight loss, lethargy, enlarged lymph nodes), dermatological, renal or ocular. The purpose of this article is to review the literature and to describe our own experience of certain atypical forms of canine leishmaniosis. These include specific skin lesions, monoclonal gammopathy, renal failure (without any other signs), chronic colitis, haemostatic problems and disorders of the cardiovascular, respiratory and musculo-skeletal systems.

Interstitial lung disease in feline immunodeficiency virus (FIV) infected cats

Postmortem bronchoalveolar lavage of feline immunodeficiency virus-infected cats indicated an alveolitis process, and histological examination of their lungs confirmed the occurrence of alveolitis, parenchymatous lymphoplasmocytic infiltration and myomatosis. Similar lymphoid interstitial pneumonitis has been described in human and animal lentiviral diseases: lymphocytic interstitial pneumonitis in HIV-1-infected human beings, and maedi in sheep infected by the maedi-visna virus. Such lymphoid interstitial pneumonitis may thus be a common feature of lentiviral infections.

Toxicity and kinetics of amitraz in dogs

OBJECTIVE

To evaluate the toxic effects of amitraz in dogs and their reversal by various doses of atipamezole.

ANIMALS

6 male 1-year-old Beagles.

PROCEDURE

Dogs were given 100 mg of amitraz/kg of body weight, PO. Atipamezole was administered at 3 dose rates. Clinical examination and blood sample collection were performed regularly for 48 hours to examine biological parameters and determine the toxicokinetics of amitraz as well as the efficacy of the antidote. A specific high-performance thin layer chromatographic method was developed to determine plasma amitraz concentrations.

RESULTS

Clinical signs of toxicosis included sedation, bradycardia, polyuria, hypothermia, and hyperglycemia, all of which could be related to the alpha 2-agonist activity of amitraz, and were reversed by low doses of atipamezole (50 micrograms/kg, IM), a potent alpha 2-antagonist, within 10 minutes after injection. Peak plasma concentrations were observed after 5 hours, and the elimination half-life was long (about 24 hours).

CONCLUSIONS

All clinical and biological effects observed during the course of amitraz poisoning could be attributed to the parent compound itself and were reversed by low doses of atipamezole. The half-life of amitraz was substantially longer than that in other studies because of the high dose administered.

CLINICAL RELEVANCE

Atipamezole can be administered i.m. to dogs with severe amitraz poisoning to reverse all the effects observed.

Visna-maedi virus-induced expression of interleukin-8 gene in sheep alveolar cells following experimental in vitro and in vivo infection

Visna-maedi virus is a lentivirus which causes inflammatory disorders in sheep, including a chronic interstitial lung disease resembling that observed in human immunodeficiency virus type 1 (HIV 1) infection. In view of our previous demonstration of the production of neutrophil chemotactic activity by alveolar macrophages, and given the lymphocytic and neutrophilic nature of the alveolar cell infiltrate in both naturally and experimentally infected animals, we hypothesized that interleukin-8 (IL8) could be a candidate for at least part of the chemotactic activity we described. In this study, we investigated IL8 mRNA expression following visna-maedi virus infection. Northern analysis of total RNA using an ovine IL8-specific probe demonstrated that the IL8 gene is upregulated in alveolar macrophages as a consequence of in vitro infection and in alveolar cells from experimentally infected animals. Using a semi-quantitative RT-PCR method, we showed that various levels of IL8 mRNA are expressed by alveolar cells from infected animals and that they correlate with the intensity of the lesions. In conclusion, visna-maedi virus is able to induce IL8 mRNA expression in sheep alveolar cells. Results from in vivo infected animals suggest that IL8 could play a role in the early build-up of visna-maedi virus-induced lesions.

[Oslerosis of the dog: diagnostic and therapeutic status]

Oslerus osleri is a metastrongle whose first-stage larvae are expectorated by the bitch, and which are infecting for pups; few cases are described from France. The biological features of this parasite, diagnosis and therapy are described in a first bibliographic part. 29 of 66 dogs examined were infected with Oslerus osleri. We investigated the cause of their chronic coughing, which was not cured by routine therapies. Several diagnostic methods were used, of which endoscopy was the best. The following drugs were used to treat infection with Oslerus osleri: ivermectin, levamisole, oxfendazole and fenbendazole. The last-mentioned two drugs are safe for dogs and very effective against this parasite.

Increased expression of tissue factor mRNA and procoagulant activity in ovine lentivirus-infected alveolar macrophages

To link ovine lentivirus infection to lung tissue damage, we studied the procoagulant response in alveolar macrophages from experimentally infected lambs and in in vitro infected alveolar macrophages. We cloned ovine tissue factor cDNA and analysed its in vitro expression by Northern blotting. Visna-maedi virus induced tissue factor mRNA. In order to correlate this mRNA induction with its cellular function, we analysed macrophage procoagulant activity after in vitro and in vivo infection. The procoagulant activity was increased by interaction with the virus in both cases. Thus, visna-maedi virus-induced expression of tissue factor mRNA was associated with enhanced macrophage procoagulant activity. These findings indicate an active role of alveolar macrophages in the pathogenesis of these inflammatory lung lesions.

Early events in the experimental interstitial lung disease induced in sheep by the Visna-maedi virus

Visna-maedi virus is a lentivirus closely related to the human immunodeficiency virus type I (HIV-I). During spontaneous infection of sheep by Visna-maedi virus an interstitial lung disease is observed. It is characterized by an alveolitis, peribronchovascular lymphoid nodules, alveolar wall thickening and myomatosis. In order to decipher the pathology of this lentiviral infection we have induced this disease in colostrum-deprived newborn lambs.

Characterization of the lymphocytic alveolitis in visna-maedi virus-induced interstitial lung disease of sheep

In order to investigate the contribution of lymphocytes to interstitial lung disease in animals with visna-maedi infection, we studied in parallel bronchoalveolar cells and lung tissue from slaughter-house animals (n = 29) and from colostrum-deprived lambs transtracheally inoculated with field isolates of visna-maedi virus (n = 9) or saline (n = 6). Lymphocyte subpopulations were identified in bronchoalveolar lavage by immunofluorescence and flow cytometry analysis and in lung tissue using indirect immunohistochemistry. In infected animals a lymphocytic alveolitis containing CD4 and CD8 lymphocytes was observed. Peribronchovascular lymphoid nodules comprise mostly CD4 lymphocytes. Alveolar lymphocytes of both subsets displayed increased expression of MHC class II antigens in animals with naturally occurring maedi but not in experimentally infected ones. A sequential process of lymphocyte attraction and activation is likely to occur in vivo as part of the alveolitis.