19 Feb 2018

Mortality and predictors in dogs treated for parvoviral enteritis

Alex Gough’s latest Research Review also looks at studies into thermoregulation in dogs, the effects of gabapentin in cats, and emphysematous cystitis.

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Alex Gough

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Mortality and predictors in dogs treated for parvoviral enteritis

Image © arcyto / Fotolia

Canine parvovirus is a common infectious condition, particularly affecting puppies, and often requires intensive treatment.

Sarpong et al1 performed a retrospective case series and case-control series to assess mortality and factors affecting prognosis in dogs treated for parvoviral enteritis on an outpatient basis.

A total of 130 dogs were included in the study. Short-term outcome was determined by a telephone call to the owner. The treatment given was at the discretion of the clinician in charge of the case.

In total, 25% of cases did not survive. However, cases fed a caloric supplement every two to four hours had a lower mortality rate (19%).

Breeds over-represented were Chihuahuas, German shepherds and pitbull-type dogs. Males were also over-represented. However, age, weight and sex did not affect likelihood of survival.

The authors noted the 75% survival rate should be taken into consideration when discussing treatment options with clients who cannot afford hospitalisation.

Thermoregulation in dogs

Panting is one mechanism by which dogs can thermoregulate, by increasing evaporation from the respiratory tract. Dogs with brachycephalic conformation may struggle to regulate their body temperature in this fashion, and body condition may also have an effect.

Davis et al2 performed a prospective study of thermoregulation in 52 brachycephalic and 53 non-brachycephalic dogs.

The dogs were exposed to a cold environmental temperature and a hot temperature at least one hour later. The dogs acclimatised for 15 minutes and were then placed in a plethysmograph for 10 minutes to allow measurement of respiratory pattern. Body temperature was also measured.

Increased body condition score was associated with an increased body temperature, regardless of whether the dog was brachycephalic, and increased body condition led to a reduced tidal volume.

Brachycephalic dogs were found to increase their respiratory rate more than non-brachycephalic dogs in response to increased environmental temperature.

The authors noted although brachycephalic dogs had a poorer capacity for thermoregulation than non-brachycephalic dogs, body condition had a bigger effect on body temperature.

Effects of gabapentin on stress in cats

Gabapentin is a drug used in veterinary medicine for the treatment of neuropathic pain and, sometimes, epilepsy.

A randomised, blinded crossover trial by van Haaften et al3 assessed the effect of gabapentin on stress in cats. A total of 20 healthy cats with a history of fractious behaviour or stress during a visit to the vets were included in the study.

The cats were randomised to receive either 100mg of gabapentin or placebo 90 minutes before a visit to the vets. A week later, the other treatment was given before a second visit. Physical examination, blood pressure, an owner score of stress (during transportation and examination) and a vet score of compliance were recorded.

The owner and vet scores of stress and compliance were significantly lower in cats that received gabapentin, compared to placebo. However, sedation was common, and ataxia, hypersalivation and vomiting were noted in some cases. These side effects were quickly self-limiting.

The authors concluded gabapentin is a safe and effective treatment to reduce stress and aggression, and improve compliance in cats being brought to the vets for examination.

Ammonia concentrations in arterial and venous blood

Elevated ammonia is thought to be a major contributor to hepatic encephalopathy, often occurring due to the presence of portosystemic shunts.

Or et al4 performed a study to compare ammonia concentrations in arterial and venous blood, and cerebrospinal fluid (CSF) in dogs with and without extrahepatic portosystemic shunts (EHPSS). A total of 19 dogs with congenital EHPSS and 6 healthy control dogs underwent transsplenic portal scintigraphy under anaesthesia to evaluate the presence of EHPSS. While anaesthetised, arterial, venous and CSF samples were taken to measure ammonia levels by two different methods.

The blood and CSF samples from the dogs with EHPSS had significantly higher ammonia levels than the controls, and the blood samples from EHPSS dogs were much higher than the reference range.

The authors noted the high CSF ammonia levels may indicate increased permeability of the blood-brain barrier to ammonia in dogs with portosystemic shunts.

Leflunomide in dogs with immune-mediated diseases

A number of drugs can be used instead of, or in addition to, steroids in the treatment of immune-mediated disease.

Sato et al5 performed a retrospective review of the use of leflunomide in dogs with immune-mediated diseases.

A total of 92 dogs were included in the study. Of those, 11 dogs experienced adverse events, which included 3 cases of diarrhoea, 3 cases of unexplained haemorrhage, 2 cases of lethargy and 2 cases of thrombocytopenia. Adverse events were noted more often in dogs treated with higher doses.

Of 17 dogs where it was possible to evaluate treatment response, 12 showed a positive response. No significant difference was noted in the dose of leflunomide in dogs that responded to treatment, compared to those that did not.

The authors suggested using lower doses of leflunomide than recommended.

Rectal, axillary and auricular temperatures

The standard way of obtaining a patient temperature in veterinary medicine is rectally.

Cichocki et al6 performed a study to compare axillary and auricular temperatures to the gold standard of rectal temperatures. Rectal and auricular temperatures had the best agreement, but the discrepancy was up to 2.2°C, and the discrepancy between rectal and axillary temperature was as high as 4°C.

The authors concluded auricular and axillary temperatures were poor predictors of rectal temperature, and recommended these measurements are not used as a substitute for rectal temperature.

Emphysematous cystitis

Emphysematous cystitis is a condition involving gas being found in the bladder wall or lumen.

Merkel et al7 performed a retrospective study of the findings in 27 dogs with emphysematous cystitis. The most common clinical sign observed was haematuria. Gas was detected in the bladder wall and lumen in 52% of cases, only the lumen in 15%, and only the bladder wall in 33%.

All but one of the cases had a concurrent disease, with 33% of cases having diabetes mellitus. In total, 26% had neurological disease and 19% had adrenal disease. A variety of bacteria were isolated, including Escherichia coli and Enterococcus.

  • Some medications mentioned in this article are used under the cascade.