Salmonellosis as an Asymptomatic Carrier State or as Acute Enteritis in the Prehensile-Tailed Porcupine (Coendou prehensilis)
Enteric bacterial disease is a common ailment of zoo mammals, affecting a broad range of taxa. Pathogenic bacteria including Salmonella are of major zoonotic concern. In this report, salmonellosis is described in prehensile-tailed porcupines (Coendou prehensilis) as an asymptomatic carrier state and also as acute, potentially fatal enteritis. Salmonella was detected in four prehensile-tailed porcupines from the Albuquerque BioPark or from records from the receiving institution over the last 15 years. Cases are described, and treatment depended upon whether clinical signs were present. Acute salmonellosis should be treated with appropriate antibiotic therapy, but it is generally not recommended to treat asymptomatic animals due to the potential to create antibiotic-resistant strains.
The prehensile-tailed porcupine is a nocturnal, herbivorous rodent that originates from South America. This species is frequently used as an education animal; therefore, this information is especially important as direct or indirect contact with the public is possible. Animals that have direct or indirect contact with the public should be routinely screened for zoonotic pathogens.
Four cases of salmonellosis in prehensile-tailed porcupines (Coendou prehensilis) have been diagnosed at the Albuquerque (ABQ) BioPark or noted in records from the previous institution in the last 15 years. Three of seven porcupines that died at the ABQ BioPark over the last 15 years were positive for Salmonella at the time of death. Other causes of death in this species were pneumonia, neoplasia (round-cell tumor, unable to classify), stillborn, and undetermined. An informal survey of AZA institutions holding three or more prehensile-tailed porcupines identified no additional cases of positively diagnosed salmonellosis in this species, although diarrhea or other gastrointestinal symptoms were common.
Case 1: A hand-raised nine-year-old female prehensile-tailed porcupine was discovered to be an asymptomatic I carrier. In February of 2012, it was diagnosed with Salmonella enterica Type 1, subspecies enterica, which was sensitive to most antibiotics. Treatment was not pursued since it is generally not recommended to treat an asymptomatic carrier. As an education/outreach animal, the animal’s use around the public became very limited due to the potential zoonotic transmission of Salmonella. It was found acutely lethargic on September 23, 2014 and had not eaten overnight which was unusual for her. The porcupine was then anesthetized for physical examination, bloodwork, radiographs, and further treatment. Upon physical examination, mild dehydration was noted and moderate distension of the abdomen. Radiographs revealed a gas-filled stomach and cecum. Bloodwork revealed mild hyperglycemia. Despite supportive care and treatment with subcutaneous fluids and antibiotics, the porcupine was found dead four hours later. Diarrhea was noted only during anesthetic recovery. Necropsy confirmed moderate gas distension of the stomach and cecum, and pink-purple discoloration of the stomach and small intestine. Histopathology confirmed gastritis with loss and dysplasia of gastric glands. No evidence of infectious organisms was noted upon routine staining, but the appearance was like that associated with Helicobacter species. There were no microscopic lesions in the small or large intestine typical of salmonellosis. The pathologist suggested that chronic gastritis and fibrosis in the stomach may have led to acute bloat, but this could not be confirmed. In addition, this porcupine also had arteriosclerosis.
Cases 2 and 3: Two nine-year-old female porcupines housed in a mixed-species exhibit with golden lion tamarins (Leontopithecus rosalia) were anorexic with no other signs of illness two days prior to death. Case 2 was anesthetized for examination, bloodwork, and radiographs. Physical examination revealed a distended abdomen and muffled heart sounds. Radiographs of this animal showed gas distension of the colon and cecum. This porcupine died one hour after anesthetic recovery. Necropsy revealed a distended cecum containing bloody fluid. Bacterial cultures were not obtained from this animal, but symptoms were presumed to be due to bacterial enteritis from Salmonella C2 serovar Newport, Clostridium perfringens, and Campylobacter, as these bacteria were isolated from Case 3. Case 3 was anesthetized on the same day as Case 2. This porcupine was also noted to have a gas-distended cecum on radiographs, but the colon was not distended. Anesthetic recovery was uneventful, but the animal became agonal one hour after recovery and it was humanely euthanatized. Just prior to death, it passed some malodorous liquid diarrhea. Salmonella C2 serovar Newport, Clostridium perfringens, and Campylobacter were isolated from the cecum.
Case 4: A female prehensile-tailed porcupine presented with diarrhea and lethargy and was diagnosed with Salmonella group B at one year of age. It was treated with sulfamethoxazole and trimethoprim (Tribrissen, Schering-Plough, Elkhorn, NE 68022 USA) initially and then switched to gentamicin (brand information not available) after bacterial culture and sensitivities were reported. This animal was also treated with probiotics (brand information not available) and this porcupine survived. However, the porcupine died acutely at 10 years of age. Upon necropsy, reddened small intestine was noted, but no significant lesions were noted on histopathology and a bacterial culture was negative for pathogens. A cause of death was not determined in this case.
In each of the cases in which a porcupine died acutely, a gas-filled cecum and stomach or intestine was noted upon radiographs. In this species, anorexic animals with or without diarrhea and gas distension of the gastrointestinal tract should raise concern for salmonellosis. This presentation should be considered urgent due to the very short time frame in which the animal may die. Diarrhea was noted in two of the four cases, one of which died a short time after the onset. Despite the fairly high occurrence of salmonellosis noted recently at the ABQ BioPark, this prevalence has not been reported at other institutions. One recent study found a low prevalence of Salmonella and STEC 0157 at AZA-accredited institutions; 0/10 rodents (porcupines included) were positive for Salmonella enterica or Escherichia coli 0157:H7.3
The zoonotic potential of Salmonella in prehensile-tailed porcupines is also of major concern. Salmonella enterica is considered ubiquitous and may be shed by apparently healthy animals.4 Several studies have noted the asymptomatic shedding of Salmonella spp. in zoo carnivores and have suggested contaminated meat as a likely source.1,5 The source of Salmonella in the prehensile-tailed porcupines is unknown. The American Zoo and Aquarium Association Animal Health Committee has drafted guidelines to assist member institutions in decision making regarding the use of animals for public contact, education, and outreach. One recent study found that 14% of domestically acquired illnesses in humans caused by enteric pathogens were attributed to animal contact. Nontyphoidal Salmonella spp. were the leading cause of hospitalization out of the seven groups of pathogens studied (Campylobacter, Cryptosporidium, nontyphoidal Salmonella, Shiga toxin-producing Escherichia coli 0157, Shiga toxin-producing Escherichia coli non-0157, Listeria monocytogenes, and Yersinia enterocolitica).2
In prehensile-tailed porcupines, salmonellosis may present as either acute, potentially fatal enteritis, or as an asymptomatic carrier state. In cases of suspected enteritis, it is recommended that a fecal culture with antibiotic sensitivities be obtained early in the course of illness to diagnose and accurately treat the illness. In cases of asymptomatic carrier state, treatment is generally not recommended in order to avoid antibiotic resistance from developing.
The authors wish to thank John Ragsdale, DVM, PhD, DACVP, for histopathology and the education, nocturnal, and tropical America keepers at the ABQ BioPark for their excellent care of the prehensile-tailed porcupines.
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