Signalment & History
A 4.5 year old MN Rhodesian Ridgeack presents for severe progressive tetraparesis/ataxia. The owner reports that the patient collided with another dog while playing 8 months before. He didn’t display signs of pain at that moment of the trauma and until 2 months ago he was able to run with the owner. In the last few weeks the patient got worse: he is now unable to walk without assistance even though he is still eating/drinking and he can voluntarily control urinary and fecal discharge. The patient is also congenitally deaf. On today’s physical examination, hedisplays abnormal mentation. He’s unaware of the surroundings and the position of his limbs. He is severely ataxic on all four limbs, and has left head tilt but circles to the right. The patient also has CP deficits: severe in both the hindlimbs and mild in the right forelimb. In addition he is: hypermetric in the front limbs, unable to wheelbarrel on his hind limbs and unable to hemiwalk or hop on any limb.
Findings
The urinary bladder wall appears irregular and thickened due to the presence of diffuse, multiple, round to linear intramural gas opacities. In addition free intraluminal gas is noted within the urinary bladder. The stomach and intestines are diffusely gas-filled. Multiple small, linear to angular mineral opacities are identified throughout the colon. A transitional L1 vertebral body with hypoplastic ribs is seen. Four sacral segments are noted.
Diagnosis
You have identified an irregularly thickened bladder wall, characterized by the presence of diffuse, multiple, round to linear intramural gas opacities. In addition, you have seen mottled gas opacities within the urinary bladder lumen. Diffusely gas-filled stomach and intestines have been noted. Transitional L1 and 4 sacral segments were identified. These radiographic abnormalities are consistent with emphysematous cystitis, aerophagia and multiple skeletal anomalies. Urinalysis was performed and revealed the presence of blood, protein, white blood cells, and bacilli bacteria (Escherichia coli) in the urine.
Conclusions
Emphysematous cystitis (EC) has been reported in humans, dogs, cats and a cow. In veterinary medicine it represents an uncommon type of complicated urinary tract infection characterized by accumulation of gas within the urinary bladder wall and lumen. E. coli is the most frequently isolated pathogen in humans and it’s commonly isolated in dogs and cats with EC, as well as Klebsiella spp., Proteus spp., Clostridium spp., and Aerobacter aerogenes. EC are most commonly found in diabetic patients but it has also been described in patients with primary renal glycosuria, urinary tract obstruction, chronic urinary tract infections, neurgenic bladder dysfunction, morphologic abnormalities of the genitourinary tract and immunosuppression. Signs referable to a lower urinary tract infection, such as hematuria and pollakiuria and pneumaturia have been reported. Iatrogenic causes of gas within the urinary tract and abnormal anatomic conditions such as the presence of fistulas, must first be investigated and ruled out. In the absence of those conditions, detection of intramural and/or intraluminal gas within the urinary bladder on radiographs, ultrasound or computed tomography is considered pathognomonic for EC. Ultrasonography can be useful for detection of early cases of EC where only a small amount of gas is present. Performing an ultrasonographic examination with the patient in both recumbent and standing positions may help in differentiating urinary calculi from luminal or intramural gas within the bladder. CT is the modality of choice for the diagnosis of EC in people.
Abdominal ultrasound revealed a medullary mass on the caudal pole of the left kidney, mesenteric lymphadenopathy and confirmed the radiographic finding of emphysematous cystitis. FNA of the renal mass was performed and showed a marked macrophagic and neutrophilic inflammation with many algal-like organisms most consistent with Prototheca. MRI evaluation of the cervical spine and neurocalvarium was performed too and results were consistent with encephalomyelitis with hydromyelia and central canal dilation associated with the cranial and mid cervical spine. Prototheca spp. are saprophytic algae that rarely infect immunocompromised hosts. There is a wide variety of clinical signs due to systemic dissemination of protothecal organisms but classically infection in dogs causes diarrhea with hematochezia, lymphadenoapthy and uveitis. Cutaneous ulcerative lesions and central neurological signs can also occur. Infiltration of multiple organs including the kidneys is typical and is revealed by histological examination.
Emphysematous cystitis (EC) in dogs is caused by microorganism such as Escherichia coli, Aerobacter aerogenes, Proteus spp., and Clostridium spp. In dogs EC appears to occur mainly in association with diabetes mellitus and primary renal glucosuria. In these cases, glucose-fermenting bacteria or yeast in the bladder ferment glucose to produce carbon dioxide, which collects within the bladder wall and lumen as very small gas bubbles. As the pathogens use part of the urinary glucose, glucosuria becomes an inaccurate way to monitor glycemia. In few instances secondary EC (due to chronic urinary tract infection, bladder trigone diverticulum or long standing administration of steroids) without underlying glucosuria have been described. In these nonglucosuric patients production of gas is caused by bacterial breakdown of urinary albumin. Common clinical signs of EC are represented by recurring hematuria, pollakyuria and stranguria. Three radiographic stages of EC have been described in human medicine. In stage one, a clear 1 mm zone may be seen around the contrast medium. In stage two, the bladder wall is irregular and thickened due to the presence of intramural gas. In stage three, free intraluminal gas is seen. A grading system for use in veterniary patient has not been established yet. On radiographs, the presence of gas within the lateral ligaments of the urinary bladder have been reported too and might be seen associated with the more commonly found intramural and intraluminal gas opacities. Bright echoes and reverberations typical of gas are noted ultrasonographically, due to gas entrapped in the bladder wall. In addition, the urinary bladder may appear reduced in size and echogenic content may be seen. The ultrasonographic examination is more sensitive for detection of gas within the bladder at an early stage of EC. Prevalence of EC may be underestimated if only a radiographic examination is performed.
Canine protothecosis is an uncommon disease caused by algae of Prototheca spp. Prototheca have demonstrated the capability to be an infectious agent in several species and protothecosis has been most frequently reported in human, canine, feline and bovine patients. Protothecosis in dogs is unique in many aspects when compared with the disease process in humans, cats and cattle. Patients are commonly presented with ophthalmic or gastrointestinal signs, such as diarrhea, often accompanied by vomiting and weight loss. Neurologic signs such as paresis, head tilt, cervical pain, circling and ataxia, lameness, neurologic blindness and skin lesions have also been reported. Affected dogs tend to be young to middle-aged spayed females with history of intermittent diarrhea for a number of months. They are most commonly referred to a veterinarian to evaluate worsening diarrhea, acute onset of blindness or both. At clinical examination many animals may appear healthy but frequently lymphadenopathy, fever, lameness, dehydration, deafness, head tilt and even skin lesions are revealed. Lymph node biopsy or impression cytology in patients with lymphadenopathy, culture from CSF taps in dogs with neurological signs and “vitreous” tap in patients with ocular signs showed the presence of organisms. Because of the high mortality rate associated with systemic canine protothecosis most of the published cases reports include gross pathology and histopathological results. Organs frequently affected include eyes, large intestine, kidneys, liver, skeletal muscle, myocardium, lymph nodes, thyroid, pancreas, peritoneum, and diaphragm. Additional lesion are commonly found in the brain, spinal cord, and, the cochlea. Ingestion and hematogenous and lymphatic dissemination is the presumed route of infection. The prognosis for canine protothecosis is grave to poor. Clinical sings are non specific, and often by the time a definitive diagnosis is reached, the organism has disseminated throughout the body and the condition is beyond treatment. Also, it remains unclear whether early diagnosis can truly provide a better long-term prognosis since there is currently no effective treatment of the canine disease.
References
Radiographic and ultrasonographic findings of emphysematous cystitis in four nondiabetic female dogs. Petite A. et al. Vet Radiol Ultrasound 2006; 47(1): 90-93.
Canine Protothecosis. Hollingsworth S.R. Vet Clin North Am Small Anim Pract. 2000 Sep; 30’(5): 1091-101.
