Paraquat intoxication and associated pathological findings in three dogs in South Africa

Paraquat is a bipyridylium non-selective contact herbicide commonly used worldwide. When ingestion occurs by humans and animals either accidentally, intentionally or maliciously, paraquat selectively accumulates in the lungs resulting in the production of oxygen-free radicals, causing membrane damage and cell death. Intoxicated subjects typically show progressive and fatal pulmonary haemorrhage, collapse and oedema. In individuals surviving the acute phase, pulmonary fibrosis develops. Gastrointestinal-, renal- and central nervous system clinical signs may also occur. Owing to the lack of effective treatment and absence of an antidote, the prognosis is poor. The clinical presentation, clinicopathological findings and treatment are briefly described of three dogs from one South African household, intoxicated with paraquat. Macroscopic and microscopic lesions in one dog that was necropsied, as well as pulmonary ultrastructure are detailed and illustrated for academic reference. All dogs presented with tachypnoea and dyspnoea 2–3 days after accidental paraquat ingestion. Treatment was aimed at reducing gastrointestinal absorption, enhancing elimination by diuresis and avoiding further oxidative damage by administration of antioxidants. All dogs, however, became progressively hypoxic despite treatment and were euthanised. Paraquat toxicity should be a differential diagnosis in dogs with unexplained progressive respiratory and gastrointestinal signs and renal failure. The local veterinary profession should be aware of accidental or intentional paraquat toxicity of animals. Existing literature, variations possible in canine clinical signs, measured parameters, lesions, as well as possible treatments, promising experimental antidotes and management options are discussed.http://www.jsava.co.zaam2016Animal and Wildlife SciencesParaclinical Science

Antebrachial chondrodysplasia in New Zealand white rabbits (Oryctolagus cuniculus)

Rabbits obtained from a South African rabbit breeder exhibited deformities of the distal forelimbs. The clinical, radiological and histological presentation of mid-antebrachial valgus formation (a.k.a distal foreleg curvature) in these rabbits was consistent with an autosomal recessive trait associated with a chondrodystrophic lesion of the distal ulna epiphysis 1st described in the 1960s. The impact this might have on South African farming enterprises and laboratory facilities has not been established, but the heritability and welfare implications of this condition make it a concern. Mildly affected animals can adapt to the deformity with some housing adjustments, but severely affected animals may require humane euthanasia.http://www.journals.co.za/ej/ejour_savet.htm

The effect of methadone on blood glucose, lipids and glucose‑modulating hormones in methadone‑dependent Wistar rats

A growing body of evidence indicates that opioids regulate mechanisms activated during the stress response. This study was aimed to investigate the effect of methadone dependency on blood glucose, lipids and glucose-modulating hormones in male and female Wistar rats.This study was performed on 40 Wistar rats weighing 150–350 g, in four methadone exposure and control groups of both males and females. All rats were weighed at the beginning and end of the study and their fasting blood glucose was measured using a glucometer. In order to induce addiction, methadone was injected intraperitoneal for 10 consecutive days at 5 mg/kg dose. The control group received the same volume of only normal saline. At the end of the study, the rats were sacrificed and their blood serum collected to measure cortisol, glucagon, adrenaline and lipid profile levels. There was a significant decrease in the mean final blood glucose of methadone-treated versus control male rats (p = 0.02). There was no significant glucose difference, however, in female rats. Furthermore, a decrease in the mean serum levels of triglyceride, cortisol, and adrenaline occurred in male rats of methadone-dependent compared with control animals, but there was no significant difference in these values in female rats. Our results showed that methadone significantly reduced serum glucose as well as triglyceride levels only in male rats, this being associated with a reduction in the level of counterregulating hormones of carbohydrate metabolism. Changes in lipid profiles, however, occurred independently of gender.The Vice Chancellor for the Research and Technology of the Birjand University of Medical Sciences.https://www.springer.com/journal/431882021-11-26am2021Paraclinical Science

Fatal disseminated toxoplasmosis in an immunocompetent cat

A 10-year-old domestic short hair cat was referred for investigation of anorexia and polydipsia of 3 days’ duration. Clinically the cat was obese, pyrexic (39.8 °C), had acute abdominal pain and severe bilirubinuria. Haematology and serum biochemistry revealed severe panleukopenia, thrombocytopenia, markedly elevated alanine aminotransferase (ALT) and five-fold increased pre-prandial bile acids. Ultrasonographic evaluation of the abdomen did not identify any abnormalities. Serum tests for feline immunodeficiency virus (FIV) and feline leukaemia virus (FeLV) were negative. Broad-spectrum antibiotic treatment for infectious hepatitis was to no avail; the cat deteriorated and died 72 h after admission. Necropsy revealed mild icterus and anaemia, severe multifocal hepatic necrosis, serofibrinous hydrothorax, pulmonary oedema and interstitial pneumonia. Histopathology confirmed the macroscopic findings and revealed multifocal microgranulomata in the brain and myocardium, as well as areas of necrosis in lymph nodes and multifocally in splenic red pulp. Long bone shaft marrow was hyperplastic with a predominance of leukocyte precursors and megakaryocytes and splenic red pulp showed mild extramedullary haemopoiesis. Immunohistochemical staining for Toxoplasma gondii was strongly positive, with scattered cysts and tachyzoites in the liver, lymph nodes, spleen, lungs, brain, salivary glands and intracellularly in round cells in occasional blood vessels. Immunohistochemical staining for corona virus on the same tissues was negative, ruling out feline infectious peritonitis (FIP). Polymerase chain reaction (PCR) on formalin-fixed paraffin-wax embedded tissues was positive for Toxoplasma sp., but attempts at sequencing were unsuccessful. This was the first case report of fulminant disseminated toxoplasmosis in South Africa, in which detailed histopathology in an apparently immunocompetent cat was described.S.S.N. (University of Pretoria) managed the clinical case and collected the clinical data under the supervision of J.P.S. (University of Pretoria). J.H.W. (University of Pretoria) performed the postmortem, collected specimen samples, undertook the histological examination and took the photographs. S.S.N. and J.H.W. wrote the manuscript, to which J.P.S. gave valuable input.Dr J.P. Dubey (United States Department of Agriculture) is gratefully acknowledged for preparing the wax-embedded formalin-fixed samples, performing the PCR and the attempted sequencing of the samples. Dr Dubey also wrote the PCR method and findings and helped to edit the manuscript. Dr M. Griggs and Dr N. Sundar of the Molecular Parasitology Unit, Laboratory of Parasitic Diseases, National Institute of Allergy and Infectious Diseases, Bethesda, USA are thanked for their willingness to extract DNA from wax blocks of this cat, and to attempt the sequencing. Mrs Marie van Rensburg–Smit is gratefully acknowledged for the IMH staining of the tissues and she and Mrs Elma Vorster are thanked for assisting with the transport arrangements of the wax-blocks. Mrs C. Vermeulen is also thanked for assisting with formatting of the photographs.http://www.jsava.co.zaam2013mn201

Fatal congenital anaplasmosis associated with bovine viral diarrhoea virus (BVDV) infection in a crossbred calf

Clinical disease resulting from the vertical transmission of Anaplasma marginale has only been reported on 5 occasions despite studies demonstrating successful in utero transmission. During the reported experimental induction of congenital anaplasmosis in calves, the outcome was variable but mostly led to inapparent or mild infection. There are previous case reports of fatal congenital anaplasmosis following natural infection. The clinical findings in a 2-day-old calf presented to the Onderstepoort Veterinary Academic Hospital with clinical signs of congenital anaplasmosis, which was unresponsive to treatment, are described. Subsequent post mortem diagnostic tests revealed that this calf was co-infected with bovine viral diarrhoea virus (BVDV). It is postulated that immunosuppression resulting from BVDV infection predisposed to severe, fatal anaplasmosis in this calf.Department of Production Animal Studies of the Faculty of Veterinary Science, University of Pretoria.http://www.journals.co.za/ej/ejour_savet.htm

Standing transcutaneous surgical excision of a sialolith in an 11-year-old Thoroughbred mare

An 11‐year‐old Thoroughbred mare was diagnosed with sialolithiasis of the right parotid salivary duct. A firm nonpainful subcutaneous mass was palpable in the right maxillary region adjacent to premolar 4 (tooth 108). Radiographic and ultrasonographic examinations identified a discrete mineralised ovoid mass that was hyperechoic and produced an acoustic shadow. Surgical excision of the mass was performed under standing sedation using a transcutaneous approach and the excised sialolith submitted for histopathological and mineral composition analyses. Histological examination found no evidence of a nidus at the sialolith's core. Mineral analysis of the sialolith revealed its composition to be 40% calcium phosphate (apatite) and 60% calcium carbonate. The mare recovered with no post‐operative complications and was clinically unremarkable 2 years later.https://beva-onlinelibrary-wiley-com/journal/204232922020-07-01hj2020Companion Animal Clinical StudiesParaclinical Science

Breed and anatomical predisposition for canine cutaneous neoplasia in South Africa during 2013

Cutaneous neoplasia occurs commonly in dogs and owners in consultation with their veterinarian must decide when to perform surgery to obtain a histopathological diagnosis. The objective of this study was to identify breed predispositions for canine cutaneous neoplasms and determine factors associated with malignancy. This retrospective case-series evaluated histopathology reports from two veterinary pathology laboratories in South Africa during a six-month study period. Breed predispositions were analysed using log-linear models and risk factors for malignancy were evaluated using binary logistic regression. Data were available for 2553 cutaneous neoplasms from 2271 dogs. The most frequent neoplasms were mast cell tumours (21.1per cent), histiocytoma (9.4per cent), haemangiosarcoma (8.3per cent), melanocytoma (5.8per cent) and lipoma (5.1per cent). Boxers (relative proportion (RP)=38.9; 95% CI 2.3 to 646), pugs (7.6; 1.4 to 41.0), Staffordshire bull terriers (7.0; 1.9 to 26.3), boerboels (3.8; 1.3 to 10.7), Labrador retrievers (2.7; 1.0 to 7.0) and mixed breed dogs (2.2; 1.1 to 4.4) had a higher frequency of mast cell tumours. Jack Russell terriers (OR=2.5; 95% CI 1.8 to 3.5), Rottweilers (2.3; 1.3 to 3.9), pit bull terriers (2.2; 1.1 to 4.3) and Staffordshire bull terriers (1.6; 1.0 to 2.6) were more likely to have malignant neoplasms. Dog signalment might facilitate prognosis determination for cutaneous canine neoplasia before receiving a histopathological diagnosis.http://veterinaryrecord.bmj.comhj2019Paraclinical SciencesProduction Animal Studie

Barbiturate ingestion in three adult captive tigers (Panthera tigris) and concomitant fatal botulism of one

Zoo animals, including tigers, have been reported to suffer from barbiturate intoxication, with pentabarbitone being most commonly recorded. Clinical signs range from mild ataxia to general anaesthesia with recovery over hours to days with several factors affecting hepatic barbiturate metabolism and tissue partitioning. Botulism is an often fatal intoxication in man, animals, birds and certain fish. The occurrence in carnivores is uncommon to rare, with only 2 reports found of botulism in felids. This report relates to 3 adult captive cohabiting tigers that simultaneously developed signs of abdominal discomfort, progressive ataxia, recumbency and comatose sleep resembling stage 2 anaesthesia, alternating with periods of distracted wakefulness and ataxic movements. These signs occurred 4 days after being fed the carcass of a horse that had ostensibly died of colic and not been euthanased. The male tiger that was the dominant animal in the feeding hierarchy was worst affected and had to be given intravenous fluids. The female that was lowest in hierarchy was unaffected. After 48-72 hours of treatment at the Onderstepoort Veterinary Academic Hospital the females could eat and made an uneventful recovery. The male tiger showed partial recovery but died during the night a few hours after drinking water on his return to the owner. Necropsy revealed severe oesophageal dilation and impaction with decaying grass; some of this material and water were present in the pharynx and trachea, and had been aspirated causing acute widespread bronchopneumonia. Colon content tested negative for common pesticides but, together with liver, tested positive for barbiturate. Serum taken on the day of admission had tested negative for barbiturate and the residual serum from the 3 animals later tested negative for botulinum toxin. Colon and oesophageal content from the male at necropsy were positive for Clostridium botulinum toxin type C by the mouse bioassay neutralisation test, confirming that this male had had concomitant barbiturate toxicity and botulism, and had succumbed to aspiration bronchopneumonia secondary to pharyngeal, laryngeal and oesophageal paralysis and oesophageal impaction.http://www.journals.co.za/ej/ejour_savet.htmlmn201

Comparative pathology of neurovirulent lineage 1 (NY99/385) and lineage 2 (SPU93/01) West Nile virus Infections in BALBc mice

The pathology in mice infected with neurovirulent South African lineage 2 West Nile virus (WNV) strains has not previously been described. Three- to 4-month-old male BALBc mice were infected with South African neurovirulent lineage 2 (SPU93/01) or lineage 1 (NY385/99) WNV strains and the gross and microscopic central nervous system (CNS) and extra-CNS pathology of both investigated and compared. Mice infected with both lineages showed similar illness, paralysis, and death from days 7 to 11 postinfection (PI). Two survivors of each lineage were euthanized on day 21 PI. WNV infection was confirmed by nested real-time reverse transcription polymerase chain reaction of tissues, mostly brain, in the majority of mice euthanized sick or that died and in 1 healthy lineage 2 survivor. Gross lesions caused by both lineages were identical and included marked gastric and proximal small intestinal fluid distension as described in a previous mouse study, but intestinal microscopic lesions differed. CNS lesions were subtle. Immunohistochemical (IHC)–positive labeling for WNV E protein was found in neurons multifocally in the brain of 3 lineage 1–infected and 3 lineage 2–infected mice from days 9 to 11 PI, 4 of these including brainstem neurons, and of cecal myenteric ganglion neurons in 1 lineage 2–infected day 8 PI mouse. Findings supported hypotheses in hamsters that gastrointestinal lesions are likely of brainstem origin. Ultrastructurally, virus-associated cytoplasmic vesicular or crystalline structures, or amorphous structures, were found to label IHC positive in control-positive avian cardiomyocytes and mouse thalamic neurons, respectively, and WNV-like 50-nm particles, which were scarce, did not label.National Research Foundation of South Africa and Pfizer Animal Health. Section of Pathology of the Department of Paraclinical Sciences of the Faculty of Veterinary Science, University of Pretoria, South Africa.http://vet.sagepub.comhb201

Pathology of fatal lineage 1 and 2 West Nile virus infections in horses in South Africa

Since 2007, West Nile virus (WNV) has been reported in South African horses, causing severe neurological signs. All cases were of lineage 2, except for one case that clustered with lineage 1 viruses. In the present study, gross and microscopic lesions of six South African lineage 2-infected horses and the one lineage 1 case are described. Diagnoses were confirmed by real-time reverse-transcriptase polymerase chain reaction (RT-PCR) of central nervous system (CNS) tissue and one by RT-PCR of a brain virus isolate. The CNS of all cases was negative by RT-PCR or immunohistochemistry (IHC) for African horse sickness (AHS), equine encephalosis virus, equine herpes viruses 1 and 4, other zoonotic flaviviruses, alphaviruses, and shunivirus, and either by immunofluorescence or IHC for rabies. Gross visceral lesions were nonspecific but often mimicked those of AHS. The CNS histopathology of WNV lineage 2 cases resembled the nonsuppurative polioencephalomyelitis reported in the Northern Hemisphere lineage 1 and recent Hungarian lineage 2 cases. Occasional meningitis, focal spinal ventral horn poliomalacia, dorsal and lateral horn poliomyelitis, leucomyelitis, asymmetrical ventral motor spinal neuritis and frequent olfactory region involvement were also seen. Lineage 2 cases displayed marked variations in CNS lesion severity, type and distribution, and suggested various viral entry routes into the CNS, based on findings in experimental mice and hamsters. Lineage 1 lesions were comparable to the milder lineage 2 cases. West Nile virus IHC on CNS sections with marked lesions from all cases elicited only two antigen-positive cells in the olfactory cortex of one case. The presence in the CNS of T-lymphocytes, B-lymphocytes, plasma cells and macrophage-monocytes was confirmed by cluster of differentiation (CD) 3, CD20, multiple myeloma oncogene 1 (MUM1) and macrophage (MAC) 387 IHC.http://www.jsava.co.zaam201