Comparative and Veterinary Pharmacology

potential, the most important gastro-intestinal nematodes of dogs and cats in many
urban environments are the hookworms (Ancylostoma caninum, Ancylostoma tubae-
formae, Uncinaria stenocephala), the ascarids (Toxocara canis, Toxocara cati) and,
in the case of dogs, the whipworms (Trichuris vulpis) (Bowman et al. 2003 ). Some of
these nematode species are of public health importance because of their zoonotic
potential. For example, human contact with the infective larvae of hookworms
(Ancylostoma braziliense, A. caninum, U. stenocephala) can cause skin eruptions
ranging from mild cutaneous irritation (“ground itch”) to the more severe pruritic
lesions of cutaneous larva migrans (creeping eruption caused by hookworm larvae
migrating in the human skin) (Hendrix et al. 1996 ). A more insidious manifestation
of zoonotic hookworm infection is eosinophilic enteritis (Kopp et al. 2008 ).
Ingestion of infectiveToxocaraeggs can result in visceral larva migrans, ocular
larva migrans and covert toxocariasis in humans (Taylor and Holland 2001 ). Given
the importance of the human–animal bond and the high level of pet ownership in
many modern societies, it is important to minimise transmission of parasitic
zoonoses. Whilst appropriate hygiene measures such as hand washing are essential,
regular anthelmintic dosing of pets is also important in treating animals and
controlling environmental contamination with these nematodes. As the pre-patent
period (time needed for the infective larvae to become egg-producing adults) of the
highly fecundToxocara spp.is just over 4 weeks, monthly treatment with long
acting drugs can minimise the risk of environmental contamination resulting from
patent infection. This frequency of treatment is particularly relevant in high risk
circumstances, wherein pets have regular access to the outdoors and especially if
the household includes young children (Esccap 2006). Depending on the level of
owner compliance and the risk scenarios, a de-worming frequency of at least four
times a year, or alternatively less frequent treatments combined with regular faecal
examinations, are generally recommended.

2.2.2 Cestodes

Echinococcus multilocularisandEchinococcus granulosusare zoonotic tapeworm
species of major public health concern. Human alveolar echinococcosis is a hepatic

Table 2The macrocyclic lactones: Pharmacokinetic properties in cattle
Dose
(mg/
kg)

Route AUC

(ng.d/

mL)

Cmax

(ng/

mL)

Tmax

(days)

CL

(L/h/

kg)

Vdss

(L/

kg)

Terminal

T1/2

(days)

References

Ivermectin 0.2
0.2
0.5

IV

SC

Top.

254

361

116

442

31.7

12.2

0

3.98

3.40

0.033

2.2

2.69

4.32

5.30

Wilkinson et al. ( 1985 )
Toutain et al. ( 1997 )
Gayrard et al. ( 1999 )
Doramectin 0.2
0.2
0.5

IV

SC

Top.

• 
  

  511
  168

  
  

  32.6
  12.2

  
  
  
  
  • 5.31
    4.30
  
  
  
  

0.013

1.7

3.71

5.39

9.80

Wicks et al. ( 1993 )
Toutain et al. ( 1997 )
Gayrard et al. ( 1999 )
Moxidectin 0.2
0.2
0.5

IV

SC

Top.

195

162

105

• 
  

  33.5
  13.4

  
  

  0.369
  1.0

  
  

0.046

3.0

2.97

10.3

6.40

Lifschitz et al. ( 2002 )
Lifschitz et al. ( 2002 )
Sallovitz et al. ( 2003 )
Eprinomectin 0.5 Top. 239 43.8 2.05 – – 2.03 Alvinerie et al. ( 1999 )

Population Medicine and Control of Epidemics 119