Читать книгу Infectious Disease Management in Animal Shelters - Группа авторов - Страница 145

In the shelter, the most common causes of intestinal disease associated with mortality are the canine and feline parvoviruses. Suspicion and caution for this disease, therefore, is high; however, no clinical or gross finding is specific to parvoviral enteritis. This is a good reason to perform a necropsy on a dog or cat that is either suspicious for or known to be infected with parvovirus.

1 Establishing cause:Tissues for histology: Necropsy with histology can confirm the presence of parvovirus and would be important in ruling out parvovirus during an investigation of an unusual outbreak of GI disease. Acute cases of parvovirus are nearly pathognomonic by histologic analysis and chronic (historic) cases can also be detected by a pathologist; the architecture of the small intestine is not restored to normal for two to three weeks post‐infection.Other tests: In dogs, although the parvovirus antigen tests on feces are highly sensitive during viral shedding in the early stages of infection, these peak viral titers are brief and occur at the same time as, or prior to, the onset of clinical signs (Greene 2011). Subsequent viral shedding is known to fluctuate, and if the fecal antigen test is performed late after infection, virus in feces may be undetected. Testing of nearby, recently exposed animals is warranted, and in an animal that has died, feces should be retested at the time of necropsy with fecal material collected from pooled segments of the lower intestine (duodenum, jejunum, and colon). Numerous cases of dogs or cats have been seen whose feces were negative one to two days prior to death and submitted for evaluation of “non‐parvoviral diarrhea.” These same animals were often positive by fecal antigen tests at the time of necropsy and in these cases, there was concurrent histologic confirmation of parvoviral disease to establish etiology.

Tissue and fecal samples from dogs or cats collected at the time of necropsy are also useful for PCR amplification of virus. There is a higher sensitivity by using the PCR on infected tissues as compared with fecal antigen retrieval (Decaro and Elia 2005). In addition, many laboratories offer additional diagnostic methods on tissue samples such as immunofluorescence or immunohistochemistry.

1 Unusual presentation:

The progression of any disease can vary greatly among affected animals. Among the factors that can alter the “normal” course of disease are co‐infections, viral dose and virulence, and/or the animal's age, breed, and clinical presentation.

1 Concurrent disease(s):

Parvoviral disease, even when suspected or confirmed clinically, may be exacerbated by concurrent infections with bacteria, Giardia, hookworms, or other enteric viruses such as coronavirus. Samples should be gathered that can potentially rule concurrent disease either in or out.