Persistent Feline Diarrhea: Viper’s Case
Sponsored by Antech Diagnostics
Viper, a 1-year-old intact male Bengal cat, was adopted from a breeder and presented for a physical examination and neuter.
No concerns were identified on physical examination, although presurgical blood work had to be collected under sedation due to Viper’s fractious reaction to restraint. Initial laboratory work showed mild leukocytosis characterized by mature neutrophilia and mild monocytosis, as well as mild hyperglobulinemia.
The neuter procedure was routine, although Viper experienced diarrhea in the kennel while recovering, which continued after he was discharged. Metronidazole was empirically prescribed.
Viper’s Clinical Journey
Viper’s diarrhea persisted for several days at home; therefore, an AI-assisted fecal ova and parasite examination was performed. Results were positive for coccidia, and Viper was sent home with sulfadimethoxine for treatment of coccidiosis.
Viper was presented 2 weeks later for a recheck examination. Although there was some degree of clinical response, his diarrhea persisted and remained intermittent. Laboratory work was repeated, with samples being collected under sedation. Results indicated worsening neutrophilia, as well as lymphocytosis (suspected epinephrine-induced response). No ova or parasites were identified on repeat ova and parasite examination.
Because the diarrhea and inflammatory leukogram persisted, abdominal ultrasonography was performed, and a thickened mucosal lining of the intestinal wall was identified. Based on these findings, inflammatory bowel disease was considered the leading differential diagnosis. At this point, a variety of treatments were tried, including a hydrolyzed-protein diet, probiotics, and dietary fiber supplementation, but Viper’s clinical signs persisted.
Viper significantly declined over the next several months until he was presented for recheck with fetid, watery diarrhea containing mucus and blood. He owners reported he had also begun to act lethargic and vocalize in the litter box. Repeat laboratory work indicated progressive, immature neutrophilia and rising monocytosis. Repeat abdominal ultrasonography indicated there was further thickening of the colonic wall. Tylosin and vitamin B12 shots were initiated; however, once again, no improvement was seen. Euthanasia was considered due to poor quality of life for Viper and his owner, as well as how taxing these repeat veterinary visits were for him. His veterinarian recommended one more diagnostic test, as the clinic had just acquired Antech’s Keyscreen GI Parasite PCR Panel, which can detect 20 different GI parasites.1 A sample of Viper’s feces was submitted to the reference laboratory, and results came back within 24 hours and were positive for Tritrichomonas blagburni.
The Elusive Parasite: Tritrichomonas blagburni
Tritrichomonas sppcan cause chronic diarrhea in cats, with T blagburni (formerly T foetus) being the most common species identified in cats.2-4 T blagburni are pear-shaped protozoal organisms that can be confused with Giardia spp.4 Infection with T blagburni most commonly occurs among cats living in groups, and the fecal–oral route is the likely route of transmission.4 Many infected cats are asymptomatic, but those showing clinical signs most commonly have chronic diarrhea with blood and/or mucus, accompanied by large-bowel inflammation.2-4 Many cats have spontaneous resolution of diarrhea and clearance of T blagburni over a period of many years.4
Historically, T blagburni can be difficult to diagnose. On abdominal ultrasonography, it can easily resemble IBD or neoplasia. Traditional parasite testing is also problematic, as fecal smears have a low sensitivity for detecting T blagburni (14.7%2), and it can be mistaken as Giardia spp.4 Limitations of in-house fecal ova and parasite testing include intermittent shedding by parasites, human errors in interpretation, and difficulty identifying protozoal cysts. T blagburni can also be diagnosed via culture, with sensitivity falling between 26.4% and 58.8%, depending on the type of culture used.2 PCR testing is considered to be the most sensitive means of testing for T blagburni in cats.5
Viper’s Outcome
Viper was treated with ronidazole (30 mg/kg q24h for 14 days)4; however, there is no FDA-approved treatment for feline trichomoniasis, so informed consent must be obtained for this off-label use of ronidazole. Of note, treatment failure is not uncommon.4
Viper showed improvement within a few days, and his diarrhea completely resolved by the end of his 14-day treatment course. On repeat abdominal ultrasonography 1 month after ronidazole treatment was initiated, colon thickening had resolved, and Keyscreen® GI Parasite PCR Panel was repeated and was also negative.
Conclusion
Trichomoniasis can be a devastating disease for many cats and has historically presented a diagnostic challenge to the veterinary practitioner. Antech’s Keyscreen® GI Parasite PCR Panel offers a way to test for 20 different parasites, including T blagburni.1 Additional unique benefits of the Keyscreen® GI Parasite PCR include the detection of benzimidazole resistance in hookworms and determination of zoonotic potential of Giardia spp.1,6
