Short Takes: October 2011

Understanding Cytauxzoonosis
Cytauxzoonosis — often a fatal infection in domestic cats — is a disease caused by the parasite Cytauxzoon felis, which is transmitted by the bite of a tick. Most affected cats are young adults with exposure to the outdoors and vague clinical signs of lethargy and anorexia. 


Treatment for cytauxzoonosis is usually imidocarb diproprionate, but a combination of atovaquone and azithromycin (A&A) has also been utilized as a treatment. (neither form of therapy has been prospectively evaluated for efficacy, however).

Eighty acutely ill cats with Cytauxzoon felis infection were treated at various veterinary clinics. Of 53 cats treated with A&A, 32 (60 percent) survived to discharge. Only seven of 27 cats (26 percent) treated with imidocarb survived. Still, mortality remained high with approximately 40 percent of A&A treated cats dying in the hospital. 

The course of illness is swift and most cats that died did so shortly after presentation for care. The study (“Efficacy of atovaquone and azithromycin or imidocarb dipropionate in cats with acute cytauxzoonosis,” Journal of Veterinary Internal Medicine, 2011) indicates that efforts should remain focused on prevention of disease — either through minimization of exposure to tick vectors or through development of chemoprophylaxis or vaccination.

Treatment of Kidney Injuries
Peritoneal Dialysis (PD) can be used to manage acute kidney injury that is refractory to fluid therapy. PD utilizes the peritoneum as a semipermeable membrane in order to move solutes and water between blood in the peritoneal capillaries and fluid (dialysate) instilled in the peritoneal cavity. This study (“Peritoneal dialysis in cats with acute kidney injury: 22 cases [2001–2006]”, Journal of Veterinary Internal Medicine, 2011) of the medical records of 22 cats with acute kidney injury examined the indications, effectiveness, outcomes and complications associated with use of PD in the affected cats.

Indications for peritoneal dialysis include acute kidney injury caused by toxins, bilateral ureteroliths, bilateral ureteral ligation as a complication of ovariohysterectomy, and unknown causes.

For all cats on PD, the median survival time was four days, though the median survival time for cats discharged from the hospital was 774 days. Dialysate retention and sequestration of dialysate under the skin were the most common complications noted. Results found a significant decrease between the pre-and post-dialysis results for blood urea nitrogen, creatinine, potassium, phosphorus, total protein, and albumin concentrations.

How is Cowpoxvirus Dangerous?
Cowpoxviruses affect a number of different species, and are found in Europe and Asia. Because wild rodents are the reservoir, hunting cats may be infected from their prey. This study (“Poxvirus infection in a cat with presumptive human transmission,” Veterinary Dermatology, 2011) describes a case of cowpox infection in a cat and transmission to a caretaker.

A shelter cat in Germany was treated for facial dermatitis, but despite the use of various therapeutics, the lesions worsened. Because of this, the cat was euthanized — cowpoxvirus with systemic involvement was found on post mortem examination. Two weeks before euthanasia, a caretaker at the shelter was scratched by the cat on his hand, and developed an infection unresponsive to antibiotics.

Cowpoxvirus infection was diagnosed retrospectively based on serum testing of the caretaker. In parts of the world where cowpoxvirus infection occurs, it should be included in the list of potential ulcerative skin lesions in outdoor cats and the people in contact with them.