Evaluation of tongue as a complementary sample for the diagnosis of parvoviral infection in dogs and cats

Integrated Use of Molecular Techniques to Detect and Genetically Characterise DNA Viruses in Italian Wolves (Canis lupus italicus)

Simple Summary

In our study, different quantitative and qualitative molecular techniques were used to detect and genetically characterise Carnivore protoparvovirus 1, Canine adenovirus type 1 and 2 (CAdV-1 and CAdV-2), and Canine circovirus (CanineCV) in Italian wolves (Canis lupus italicus) of the Italian Apennines. Carnivore protoparvoviruses were the most frequently detected viruses, followed by CanineCV and CAdV. All the wolves tested positive for at least one of the DNA viruses screened, and 47.8% of the subjects were coinfected with two or three viruses. From viral sequences analysis, close correlations emerged between the viruses identified in the wolves and those circulating in domestic dogs, suggesting that the same viruses infect wolves and domestic dogs. Further studies are needed to investigate if pathogens are transmitted between the two species.

Abstract

In this study, internal organs (tongue, intestine, and spleen) of 23 free-ranging Italian wolves (Canis lupus italicus) found dead between 2017 and 2019 were tested for Carnivore protoparvovirus 1, Canine adenovirus (CAdV), and Canine circovirus (CanineCV) using real-time PCR assays. Genetic characterisation of the identified viruses was carried out by amplification, sequencing, and analysis of the complete viral genome or informative viral genes. All the wolves tested positive for at least one of the DNA viruses screened, and 11/23 were coinfected. Carnivore protoparvoviruses were the most frequently detected viruses (21/23), followed by CanineCV (11/23) and CAdV (4/23). From the analysis of the partial VP2 gene of 13 carnivore protoparvoviruses, 12 were canine parvovirus type 2b, closely related to the strains detected in dogs and wild carnivores from Italy, and one was a feline panleukopenia-like virus. Of the four CAdV identified, two were CAdV-1 and two were CAdV-2. The complete genome of seven CanineCVs was sequenced and related to the CanineCV identified in dogs, wolves, and foxes worldwide. Close correlations emerged between the viruses identified in wolves and those circulating in domestic dogs. Further studies are needed to investigate if these pathogens may be potentially cross-transmitted between the two species.

Canine Circovirus 1 (CaCV-1) and Canine Parvovirus 2 (CPV-2): Recurrent Dual Infections in a Papillon Breeding Colony

Recurrent outbreaks of sudden death and bloody diarrhea were reported in March 2013 and February 2014 in a breeding colony of Papillon dogs. During the first outbreak, 1 adult dog and 2 eight-month-old puppies died. During the second outbreak, 2 ten-week-old puppies died. One puppy from the first outbreak and 2 puppies from the second outbreak were examined at necropsy. Histologically, all 3 puppies had severe segmental crypt necrosis of the small intestine and marked lymphoid follicle depletion in the spleen and Peyer's patches. Real-time (RT) polymerase chain reaction (PCR) demonstrated abundant canine parvovirus (CPV-2) DNA (Ct<15) in the affected small intestine, and immunohistochemistry detected large amounts of CPV-2 antigen in intestinal crypt epithelium and Kupffer cells but few positive macrophages in lymphoid organs. All puppies had marked sinusoidal histiocytosis and multifocal granulomatous inflammation in mesenteric lymph nodes and spleen, prompting additional RT-PCR testing for canine circovirus 1 (CaCV-1). Very high levels of CaCV-1 DNA (Ct<13) were detected in small intestine, lymph nodes, and spleen. In situ hybridization for CaCV-1 detected rare positive nuclei of regenerating crypt epithelium but abundant amounts of CaCV-1 nucleic acid in the cytoplasm and nuclei of histiocytes in all lymphoid tissues, including granulomatous inflammatory foci and hepatic Kupffer cells. Significant levels of CaCV-1 DNA were detected in blood and serum (Ct as low as 13) but not feces from 3 surviving dogs at 2 months or 1 year after the outbreak, respectively. We hypothesize that CPV-2 infection predisposed dogs to CaCV-1 infection and ultimately resulted in more severe clinical disease.

Beyond H&E: integration of nucleic acid-based analyses into diagnostic pathology

Veterinary pathology of infectious, particularly viral, and neoplastic diseases has advanced significantly with the advent of newer molecular methodologies that can detect nucleic acid of infectious agents within microscopic lesions, differentiate neoplastic from nonneoplastic cells, or determine the suitability of a targeted therapy by detecting specific mutations in certain cancers. Polymerase chain reaction-based amplification of DNA or RNA and in situ hybridization are currently the most commonly used methods for nucleic acid detection. In contrast, the main methodology used for protein detection within microscopic lesions is immunohistochemistry. Other methods that allow for analysis of nucleic acids within a particular cell type or individual cells, such as laser capture microdissection, are also available in some laboratories. This review gives an overview of the factors that influence the accurate analysis of nucleic acids in formalin-fixed tissues, as well as of different approaches to detect such targets.

Histological characterization of dilated cardiomyopathy in the juvenile toy Manchester terrier

Dilated cardiomyopathy (DCM), the most common form of cardiomyopathy in the dog, most often occurs in certain breeds. The objective of this study was to describe a rapidly progressive form of DCM that has been recently recognized in juvenile Toy Manchester Terrier dogs (TMTs). The clinical history and gross findings were reviewed in a group of 14 TMTs, and histologic sections of heart were examined in 12 of those 14 TMTs with DCM. Histochemical and histomorphometric analyses were employed to compare the heart in TMTs affected by DCM with that of control dogs. TMTs ranged in age from 10 to 58.3 weeks, with males and females being equally affected. Affected TMT hearts contained foci of degeneration and loss of myofibers with fibrosis and mild lymphoplasmacytic infiltrates. Less prominent features included foci of acute myofiber degeneration and necrosis with or without intralesional mineralization and mild to moderate suppurative and lymphoplasmacytic infiltrates. Morphometric quantification demonstrated that the right ventricle was more severely affected (P ≤ .05) than the left ventricle with variable involvement of the interventricular septum. Immunohistochemistry for canine parvovirus was negative in all heart samples. However, the absence of parvoviral antigen does not rule out a possible viral or autoimmune cause. The presence of these myocardial lesions among closely related dogs suggests a genetic contribution to this disease process in the TMT.

Fatal Canid herpesvirus 1 infection in an adult dog

Canid herpesvirus 1 (CaHV-1) is a well-known cause of fatal hepatic and renal necrosis in neonatal puppies. In adult dogs infected with CaHV-1, papulovesicular genital lesions may be observed. CaHV-1 infection during pregnancy can lead to embryonic resorption, abortion, and stillbirth. In high-density dog populations, CaHV-1 can also contribute to kennel cough. Furthermore, recent literature has clearly documented that CaHV-1 can induce ocular disease in immature and adult dogs. The current study describes a case of fatal CaHV-1 infection in a 9-year-old spayed female Bichon Frise dog. Following a history of vomiting and diarrhea, the dog deteriorated and subsequently died. The main lesions were multifocal areas of necrosis with intranuclear inclusion bodies in the liver, adrenal gland, and small intestine, similar to the lesions observed in CaHV-1-infected puppies. Infection with CaHV-1 was confirmed on samples of liver by polymerase chain reaction, immunohistochemistry, and in situ hybridization. There was no indication of immunosuppression in this dog. Based on the results presented herein, CaHV-1 should be included in the list of differential diagnoses of hepatic necrosis in adult dogs.

Effects of canine parvovirus strain variations on diagnostic test results and clinical management of enteritis in dogs

OBJECTIVE

To estimate the prevalence of canine parvovirus (CPV) strains among dogs with enteritis admitted to a referral hospital in the southwestern United States during an 11-month period and to compare diagnostic test results, disease severity, and patient outcome among CPV strains.

DESIGN

Prospective observational study.

ANIMALS

72 dogs with histories and clinical signs of parvoviral enteritis.

PROCEDURES

For each dog, a fecal sample or rectal swab specimen was evaluated for CPV antigen via an ELISA. Subsequently, fecal samples (n = 42 dogs) and pharyngeal swab specimens (16) were obtained and tested for CPV antigen via an ELISA and CPV DNA via a PCR assay. For specimens with CPV-positive results via PCR assay, genetic sequencing was performed to identify the CPV strain.

RESULTS

56 dogs tested positive for CPV via ELISA or PCR assay. For 42 fecal samples tested via both ELISA and PCR assay, 27 had positive results via both assays, whereas 6 had positive PCR assay results only. Ten pharyngeal swab specimens yielded positive PCR assay results. Genetic sequencing was performed on 34 fecal or pharyngeal swab specimens that had CPV-positive PCR assay results; 25 (73.5%) were identified as containing CPV type-2c, and 9 (26.5%) were identified as containing CPV type-2b. No association was found between CPV strain and disease severity or clinical outcome.

CONCLUSIONS AND CLINICAL RELEVANCE

CPV type-2b and CPV type-2c posed similar health risks for dogs; therefore, genetic sequencing of CPV does not appear necessary for clinical management of infected patients. The diagnostic tests used could detect CPV type-2c.

Characterization of an outbreak of astroviral diarrhea in a group of cheetahs (Acinonyx jubatus)

A Mamastrovirus was identified in an outbreak of diarrhea in cheetahs (Acinonyx jubatus). Five young adult and two adult cheetahs presented with lethargy, anorexia, watery diarrhea and regurgitation over an 11-day period. Fecal samples were submitted for electron microscopy and culture. Electron microscopy results revealed particles morphologically consistent with an astrovirus, and no other viral pathogens or significant bacterial pathogens were identified. The astrovirus was confirmed and sequenced using consensus astroviral PCR, resulting in a 367 base pair partial RNA-dependent-RNA polymerase (RdRp) product and a 628 base pair partial capsid product. Bayesian and maximum likelihood phylogenetic analyses were performed on both the RdRp and the capsid protein segments. All animals were monitored and treated with bismuth subsalicylate tablets (524mg PO BID for 5 days), and recovered without additional intervention. This is the first report we are aware of documenting an astrovirus outbreak in cheetah.

Parvovirus infection in domestic companion animals

Parvovirus infects a wide variety of species. The rapid evolution, environmental resistance, high dose of viral shedding, and interspecies transmission have made some strains of parvovirus infection difficult to control within domestic animal populations. Some parvoviruses in companion animals, such as canine parvovirus (CPV) 1 and feline parvovirus, have demonstrated minimal evolution over time. In contrast, CPV 2 has shown wide adaptability with rapid evolution and frequent mutations. This article briefly discusses these three diseases, with emphasis on virus evolution and the challenges to protecting susceptible companion animal populations.