Pulmonary disease and mastitis have been described in sheep and goats, but no report of goat meningitis due to Cryptococcus infection has been published. Published references to caprine cryptococal disease include an outbreak of severe pneumonia by C. gattii in Spain, cryptococcal pneumonia associated to M. bovis infection, experimental and natural occurring clinical mastitis by C. neoformans and a granuloma obstructing the nasal cavity of a goat in Australia [8–12].
Non-specific clinical findings may lead to mis-diagnosis because other infectious diseases are much more common in small ruminants. The differential diagnosis in our case of lumbosacral meningitis should include other neurological diseases causing lower spinal cord lesion leading to hindquarters paresis and hyperestesia . Listeriosis and polioencephalomalacia may cause ataxia, recumbency and depression but will usually present cranial nerve deficits and central blindness. Scrapie is more common in sheep but it does occur in goats causing ataxia and intense pruritus. Other less likely causes of ataxia, paraplegia or central hyperestesia are bacterial meningitis (E. coli, Pasteurella sp., Mycoplasma sp.), inter-vertebral disc hernia and trauma (e.g. vertebral fracture), rabies, tetanus or meningitis secondary to extension of superficial lymph node infection by Corynebacterium pseudotuberculosis or Arcanobacterium pyogenes.
A definitive diagnosis requires isolation of C. neoformans from blood or body fluids such as CSF. Cryptococcal antigen latex agglutination serology (CALAS) can be performed on serum or body fluids but only provides presumptive evidence . However, in our case isolation from the CSF was not possible suggesting that negative results should not preclude the hypothesis of a cryptococcal infection of the meninges. Our results also suggest that an ante-mortem diagnosis may be difficult and so prompt anti-fungal treatment should be implemented if no response to antibiotics is evident.
Prompt treatment with amphotericin B plus flucytosine, fluconazole, itraconazole or ketoconazole, have shown some success in the treatment of cats, horses and humans. Success with oral fluconazole (5 mg/Kg/day PO for 6 months) was established in a goat with abdominal wall infection with C. gatti. However, the prognosis for infected animals that develop CNS signs is considerably worse and humane euthanasia may be warranted.
Although cryptococcosis is considered to be typically a chronic infection, in our case severe unusual neurological signs developed within days. It was not possible to estimate the duration of the lung infection but it should stressed that no respiratory signs were evident at clinical examination of this animal. Strains differ in their virulence, but the immune status of the host seems to be more important than the virulence of the strain . Systemic disease in other animals have been associated with immunosuppressing factors, such as HIV, Feline immunodeficiency virus (FIV), Feline leukemia virus (FeLV) and surgery . Gutiérrez and García Marin suggest an underlying immunodeficiency in a goat with granulomatous pneumonia caused by C. neoformans together with M. bovis, that was negative on intradermal and serologic tests for tuberculosis . There are reports of synergism between C. pseudotuberculosis and other bacteria or virus (e.g. Maedi-visna), predisposing animals to severe pneumonia and other diseases . Suggesting involvement of the caseous lymphadenitis in the pathogenesis of this cryptococcal meningitis is speculative but deserves mentioning.