Andrew Specht

Neurotoxicosis in 4 Cats Receiving Ronidazole

T ritrichomonas foetus is a protozoan that can cause chronic large-bowel diarrhea in cats. Ronidazole, a nitroimidazole, has been shown to effectively treat T foetus in cats at doses of 30 to 50 mg/kg body weight twice daily for 14 days. To our knowledge, adverse effects in cats have not been reported. This case series describes neurologic abnormalities suspected to be secondary to ronidazole administration in 4 cats. Case 1 is a 2.5-year-old male castrated Domestic Shorthair that was presented with a chief complaint of chronic, intermittent, mucohemorrhagic diarrhea of 1.5 years’ duration. The owner was unable to comment about the frequency or the urgency of defecation. The cat, when 6 weeks of age, was adopted by the owner from a rescue organization and had been housed strictly indoors since then. He resided with 5 other cats, all of whom tested negative for feline leukemia virus (FeLV) and feline immunodeficiency virus (FIV) and had no history of diarrhea. The only medical problems among the cats were occasional upper respiratory tract infections. Serum biochemistry panel, CBC, and T4; a blood smear to scan for Mycoplasma hemofelis; and (ELISA) for FeLV antigen and FIV antibody (FeLV/FIV test), performed by the referring veterinarian (rDVM) were unremarkable. Coronavirus 7B antibody titers were 1 : 80, 1 : 160, and 1 : 80 on 3 sequential serum samples in an 8-week period. Initial physical examination (PE) revealed a bright, alert, responsive, and well-hydrated cat. He weighed 4.7 kg, with a body condition score (BCS) of 7 of 9. Rectal temperature was 102.9uF, and a small amount of frank blood was observed on the thermometer. The patient had a mild serous ocular and nasal discharge, as well as gingivitis, faucitis, and halitosis. The remainder of his PE was unremarkable. Serum chemistry profile, CBC, urinalysis, abdominal ultrasound, and FeLV/FIV test were all unremarkable. Fecal flotation and direct wet preparation were negative for intestinal parasite ova and motile protozoa; Giardia ELISA was negative; stained direct preparations were unremarkable; and fecal cultures for Salmonella, Yersinia, and Campylobacter were negative. A rectal scrape revealed neutrophilic inflammation, with occasional cocci, diplococci, and a few sporulating bacteria consistent with Clostridium sp. A second fecal wet smear was positive for flagellated protozoa. Culture for Tritrichomonas foetus was positive, and the patient was prescribed ronidazole at a dose of 54 mg/kg PO q12h for 14 days. Five days after starting ronidazole, the owner reported that the cat had normal stools, lethargy, a blank stare, and appeared to be in ‘‘slow motion.’’ Neurologic evaluation of the cat was declined, and the ronidazole was continued for an additional 3 days. These clinical signs progressed, and the cat also developed an unsteady gait, pelvic-limb weakness, and trembling. Ronidazole therapy was discontinued, and the cat remained stable over several days, with gradual improvement. The patient was presented 7 days after discontinuation of ronidazole, and physical examination revealed a crouching, wide-based stance and mild ataxia in the pelvic limbs. The rest of the physical examination was unremarkable. The cat had complete resolution of its neurologic signs 1 month after discontinuation of ronidazole, and physical examination was unremarkable. The hematochezia recurred several days after discontinuing the ronidazole. Direct wet preparation of feces for motile protozoa and culture for T foetus were negative; however, the owner elected to re-treat with ronidazole at a lower dose (30 mg/kg PO q12h). The hematochezia resolved quickly, but, 12 days later, the owner reported that the cat had been unsteady, stumbling, and ‘‘spacey’’ for several days and that she had been giving him only 1 dose daily during this period. Neurologic signs resolved over a period of weeks after discontinuation of ronidazole. The patient was returned for reevaluation approximately 6 weeks after discontinuing the second course of ronidazole, and the PE was unremarkable. Culture of fresh feces was negative for T foetus. Case 2 is a 5-year-old female spayed Persian who was examined because of chronic mucohemorrhagic diarrhea since the cat was acquired from a breeder at 4 months of age. The diarrhea episodes initially occurred 6 to 8 times daily, and the cat was fecally incontinent. Routine deworming by the rDVM with pyrantel pamoate and empiric antimicrobial administration with metronidazole had no effect on the diarrhea. Dietary trials with Royal Canin Innovative Veterinary Diet Green Peas and Venison, Hill’s Prescription diet w/d, and Nestle Purina OM also had no effect on the diarrhea. The rDVM obtained multiple full-thickness biopsy specimens from the small and large intestines, which were characterized by mild lymphoplasmacytic inflammation. The cat was From the Department of Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL (Rosado, Specht); and Department of Medicine and Epidemiology, University of California at Davis School of Veterinary Medicine, Davis, CA (Marks). Reprint requests: Dr. Andrew Specht, P.O. Box 100126, Gainesville, FL, 32610; e-mail: SpechtA@mail.vetmed.ufl.edu.

Adeno-associated virus-mediated correction of a canine model of glycogen storage disease type Ia.

Glycogen storage disease type Ia (GSDIa; von Gierke disease; MIM 232200) is caused by a deficiency in glucose-6-phosphatase-alpha. Patients with GSDIa are unable to maintain glucose homeostasis and suffer from severe hypoglycemia, hepatomegaly, hyperlipidemia, hyperuricemia, and lactic acidosis. The canine model of GSDIa is naturally occurring and recapitulates almost all aspects of the human form of disease. We investigated the potential of recombinant adeno-associated virus (rAAV) vector-based therapy to treat the canine model of GSDIa. After delivery of a therapeutic rAAV2/8 vector to a 1-day-old GSDIa dog, improvement was noted as early as 2 weeks posttreatment. Correction was transient, however, and by 2 months posttreatment the rAAV2/8-treated dog could no longer sustain normal blood glucose levels after 1 hr of fasting. The same animal was then dosed with a therapeutic rAAV2/1 vector delivered via the portal vein. Two months after rAAV2/1 dosing, both blood glucose and lactate levels were normal at 4 hr postfasting. With more prolonged fasting, the dog still maintained near-normal glucose concentrations, but lactate levels were elevated by 9 hr, indicating that partial correction was achieved. Dietary glucose supplementation was discontinued starting 1 month after rAAV2/1 delivery and the dog continues to thrive with minimal laboratory abnormalities at 23 months of age (18 months after rAAV2/1 treatment). These results demonstrate that delivery of rAAV vectors can mediate significant correction of the GSDIa phenotype and that gene transfer may be a promising alternative therapy for this disease and other genetic diseases of the liver.

Glycogen storage disease type Ia in canines: a model for human metabolic and genetic liver disease.

A canine model of Glycogen storage disease type Ia (GSDIa) is described. Affected dogs are homozygous for a previously described M121I mutation resulting in a deficiency of glucose-6-phosphatase-α. Metabolic, clinicopathologic, pathologic, and clinical manifestations of GSDIa observed in this model are described and compared to those observed in humans. The canine model shows more complete recapitulation of the clinical manifestations seen in humans including “lactic acidosis”, larger size, and longer lifespan compared to other animal models. Use of this model in preclinical trials of gene therapy is described and briefly compared to the murine model. Although the canine model offers a number of advantages for evaluating potential therapies for GSDIa, there are also some significant challenges involved in its use. Despite these challenges, the canine model of GSDIa should continue to provide valuable information about the potential for generating curative therapies for GSDIa as well as other genetic hepatic diseases.

Comparison between Urine Protein: Creatinine Ratios of Samples Obtained from Dogs in Home and Hospital Settings

Background The urine protein:creatinine ratio (UPC) is used to quantify urine protein excretion and guide recommendations for monitoring and treatment of proteinuria. Hypothesis/Objectives Home urine samples will have lower UPCs than hospital samples. The objectives were to compare UPCs of samples collected in each setting and to determine whether environment of sample collection might affect staging, monitoring or treatment recommendations. Animals Twenty‐four client‐owned dogs. Methods Prospective, nonmasked study. Clients collected a urine sample from their dog at home and a second sample was collected at the hospital. Dogs receiving corticosteroids or angiotensin‐converting enzyme inhibitors were excluded, as were those with urine samples of inadequate volume, no protein on dipstick analysis, or active urine sediment. Samples were refrigerated after collection, dipstick and sediment evaluations were completed and each sample was frozen at −80°C within 12 hours. UPCs were performed on frozen samples within 2 months. Results From 81 paired samples, 57 were excluded. Of the remaining 24, 12/24 (50%) had higher hospital sample UPCs, 9/24 (38%) had identical UPCs, and 3/24 (12%) had lower hospital UPCs. The UPCs of hospital samples were higher than home samples for the total population (P = .005) and the subset with UPC > 0.5 (P = .001). Conclusions Setting and related circumstances of urine collection in dogs is associated with UPC differences; results are usually higher in hospital than in home samples. This difference has the potential to affect clinical interpretation.

Effect of common storage temperatures and container types on urine protein : creatinine ratios in urine samples of proteinuric dogs

Background Preanalytic protein adsorption to polymer and glass container surfaces may decrease urine protein concentration measurements and urine protein: creatinine ratios (UPC). Hypothesis/Objectives Urine stored in PC or glass containers will have lower UPC than urine stored in HP containers. The specific objective was to determine whether clinically relevant differences in UPC would be detected after storage in glass, PC, or HP containers using common storage times and temperatures. Animals Twelve client‐owned dogs with proteinuria. Methods Prospective, nonmasked study, divided into 2 phases. The first phase was a pilot study involving multiple (n = 5) measurements at each storage condition using 24‐hours urine samples from 2 dogs with persistent renal proteinuria of different magnitude. The second phase used urine samples from 10 dogs with proteinuria of variable magnitude. Sample aliquots were stored in HP, PC, and glass containers at 24°C for 4 hours, 4°C for 12 hours, and −20°C for 72 hours. The UPC of each was measured after storage and compared with baseline. Results Statistically significant but clinically irrelevant differences were found in phase 1. In phase 2, storage conditions did not affect urinary protein or creatinine concentrations or UPC. Conclusions and Clinical Importance Collection and storage of canine urine samples in clean HP, PC, or glass containers at 24°C for 4 hours, 4°C for 12 hours, or −20°C for 72 hours is unlikely to result in clinically relevant decreases in measured UPC values.